Dual robot welding device and welding method based on laser camera weld tracking

Abstract

The invention discloses a dual-robot welding device and a welding method based on laser camera weld tracking, which belong to the field of welding equipment, and include a moving mechanism, a visual unit and a welding unit arranged on the moving mechanism; the welding unit includes a mounting seat and a robot 2 arranged on the mounting seat; the visual unit includes a robot 1, a camera 1 and a camera 2 arranged on the mounting seat; the welding device uses a dual robot to separate the camera from the welding gun, and can perform shooting and calculation of subsequent welding points while welding, thereby improving welding efficiency; and prevents the camera positioning accuracy from being affected by the jitter of the welding gun during welding, and a camera 2 is installed outside the robot, which can shoot the welding platform in all positions, so as to locate the welding trajectory and improve the welding accuracy. No personnel is involved in the whole welding process, thereby reducing labor costs and improving production efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of welding equipment, and in particular to a dual-robot welding device and a welding method based on laser camera weld tracking. Background Art

[0002] Using a laser camera as the visual module of a welding robot can realize automated welding of the robot. The traditional method is to install the camera and the welding gun on the arm of the same robot. However, this method has the following defects: When the robot is welding, it will swing in a direction perpendicular to the weld trajectory, which will cause jitter in the captured point cloud during the welding process, resulting in excessive welding errors. Therefore, it is difficult to weld while shooting, reducing work efficiency. Summary of the invention

[0003] The present invention provides a dual-robot welding device and a welding method based on laser camera weld tracking. The dual-robot method of separating the camera from the welding gun enables the robots to perform shooting and calculation of subsequent welding points while welding, thereby improving welding efficiency and solving the problems pointed out in the background technology.

[0004] A dual robot welding device based on laser camera weld tracking, comprising:

[0005] A moving mechanism, comprising a guide rail and a gantry mounted on the guide rail and capable of moving along the X-axis direction;

[0006] A welding unit, comprising a mounting base and a second robot disposed on the mounting base;

[0007] A visual unit, comprising a robot 1, a camera 1 disposed on the robot 1, and a camera 2 disposed on the mounting seat;

[0008] The mounting seat is arranged on the gantry via a rotating shaft and can move along the Y-axis direction, and the rotating shaft can rotate along the Z-axis direction;

[0009] The second robot is provided with a welding gun.

[0010] A dual robot welding method based on laser camera weld seam tracking comprises the following steps:

[0011] Step 1: Use the moving mechanism to drive the camera 2 to shoot the welding platform section by section;

[0012] Step 2: Convert the captured point cloud from the camera coordinate system to the world coordinate system;

[0013] Step 3: Register and stitch the point cloud converted to the world coordinate system to obtain point cloud data covering the entire welding platform;

[0014] Step 4: Calculate the weld path through point cloud data;

[0015] Step 5: driving the camera 1 to move to the position just above the starting position of the weld path through the moving mechanism;

[0016] Step 6: Use camera 1 to shoot, and move robot 1 so that camera 1 moves and shoots along the weld path; calculate the welding point for each frame of point cloud data shot, and convert the welding point coordinate system to the world coordinate system;

[0017] The coordinates of the welding points in the world coordinate system are stored in a buffer in the memory, and a collection of multiple welding points constitutes a welding path;

[0018] Step 7: When the number of welding points in the buffer reaches a predetermined number, the second robot is moved to make the welding gun reach the welding position for welding;

[0019] Step 8: Move Robot 1 and Robot 2 synchronously, and make Camera 1 located in front of the welding gun's travel direction. Camera 1 takes pictures and calculates the welding points, stores them in the buffer, and reads the welding points from the buffer and sends them to Robot 2 for welding.

[0020] Preferably, the coordinate system conversion in step 2 adopts the following formula:

[0021] p w =E t E b E r T c1 p c1

[0022] Where: p c1 is the point coordinate in the camera's second coordinate system; T c1 is the transformation relationship from the camera coordinate system to the rotation axis coordinate system; E r is the transformation matrix of the rotation Z axis; E b is the transformation matrix of the Y axis; E t is the transformation matrix of the X axis; p w For p c1 Convert the point coordinates to the world coordinate system.

[0023] Preferably, the method for calculating the weld path in step 4 is as follows:

[0024] S1, calculate the normal vector of each point in the point cloud;

[0025] S2, find the point p where the normal vector suddenly changes in the point cloud, and calculate the gradient value of this point;

[0026] S3, select multiple points in the gradient direction of point p, and calculate the gradient values ​​of the multiple points one by one by the calculation method in S2, until one of the points changes to zero in the gradient z direction; then the point is the bottom corner point of the groove closest to point p;

[0027] S4, repeat S2 and S3 to obtain a number of groove bottom corner points, connect adjacent groove bottom corner points, and obtain two angle tracks of the weld groove bottom;

[0028] S5, take the midline of the two angle tracks at the bottom of the weld groove as the weld track.

[0029] Preferably, the calculation method in S1 is:

[0030] Take several points in the vicinity of any point in the point cloud, fit the plane equation through several points, and get the normal vector n of the plane through the plane equation p , the normal vector of the welding plane is n w ={0 0 1} T , then the normal direction of the point in the point cloud is:

[0031]

[0032] Preferably, the calculation method of the gradient value in S2 is:

[0033] Take several points in the vicinity of any point p in the point cloud and use the following formula to calculate:

[0034]

[0035] Where: p i are other points in the vicinity of point p, g i For point p i Directional derivative with respect to point p;

[0036] Find g for points in the neighborhood i The point with the largest change in the z direction and a negative value, g at this point i is the gradient value.

[0037] Preferably, the predetermined number in step seven is 50-100.

[0038] Preferably, in step 6, the welding point coordinate system is converted to the world coordinate system using the following formula:

[0039] p w-weld =E t E b E r T 01 T c2 p c-weld

[0040] Where: p c-weld is the coordinate of the welding point in the camera coordinate system; T c2 is the transformation relationship from the camera coordinate system to the robot flange coordinate system; T 01 is the transformation matrix of the flange coordinate system of robot 1 when camera 1 takes pictures; p w-weld The coordinates of the welding point converted to the world coordinate system.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention adopts a dual robot to separate the camera from the welding gun, and can perform shooting and calculation of subsequent welding points while welding, thereby improving welding efficiency; and preventing the camera positioning accuracy from being affected by the shaking of the welding gun during welding. A second camera is installed outside the robot, which can shoot the welding platform in all positions, and is used to locate the welding trajectory, thereby improving welding accuracy. No personnel are involved in the entire welding process, thereby reducing labor costs and improving production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the structure of the present invention when the camera 2 is shooting;

[0043] Figure 2 It is a schematic diagram of the structure of the present invention during welding;

[0044] Figure 3 This is a point cloud diagram of the workpiece to be welded according to the present invention.

[0045] Description of reference numerals:

[0046] 1-guide rail, 2-gantry, 3-mounting seat, 4-camera one, 5-camera two, 6-rotation axis, 7-welding gun, 81-robot one, 82-robot two, 9-welding platform. DETAILED DESCRIPTION

[0047] A specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific implementation.

[0048] Embodiment 1

[0049] like Figure 1 to Figure 2 As shown, a dual robot welding device based on laser camera weld tracking provided by an embodiment of the present invention includes a moving mechanism, a visual unit, and a welding unit arranged on the moving mechanism;

[0050] The moving mechanism includes a guide rail 1, a gantry 2 is provided on the guide rail 1, a guide rail axis is provided on the guide rail 1, the gantry 2 can move along the length direction (X-axis direction) of the guide rail 1, and a welding platform 9 is provided on the lower side of the gantry 2;

[0051] The welding unit includes a mounting seat 3 and a robot 82 disposed on the mounting seat 3. The mounting seat 3 is disposed on the crossbeam axis of the gantry 2 via a rotating shaft 6. The welding unit moves along the Y-axis direction on the gantry 2. The welding unit and the rotating shaft 6 can rotate along the Z-axis direction.

[0052] A visual unit, comprising a robot 1 81, a camera 1 4 and a camera 2 5 disposed on the mounting base 3;

[0053] The robot 1 81 is also arranged on the mounting base 3, and a camera 1 4 is arranged at the end thereof, and a welding gun 7 is arranged at the end of the robot 2 82;

[0054] Camera 1 4 and Camera 2 5 are both laser cameras;

[0055] Camera 2 5 is set on the mounting base 3, and camera 1 4 is located on robot 1 81. Therefore, the shaking of robot 2 82 during welding will not affect the shooting accuracy of camera 1 4 and camera 2 5, preventing excessive errors. Therefore, welding work can be carried out while camera 1 4 is shooting, thereby improving welding efficiency.

[0056] Embodiment 2

[0057] like Figure 1-Figure 3 As shown, this embodiment provides a dual robot welding method based on laser camera weld tracking, comprising the following steps:

[0058] Step 1: Use the mobile mechanism to drive the camera 2 5 to shoot the welding platform 9 section by section. Before shooting, the postures of the two robots need to be adjusted to ensure that the camera 2 5 is not blocked (such as Figure 1 shown);

[0059] Step 2: Convert the captured point cloud from the camera coordinate system to the world coordinate system. The coordinate system conversion uses the following formula:

[0060] p w =E t E b E r T c1 p c1

[0061] Where: p c1 is the point coordinate in the camera's second coordinate system; T c1 is the transformation relationship from the camera coordinate system to the rotation axis coordinate system; E r is the transformation matrix of the rotation Z axis; E b is the transformation matrix of the Y axis; E t is the transformation matrix of the X axis; p w For p c1 Convert point coordinates to the world coordinate system;

[0062] Step 3: Register and stitch the point cloud converted to the world coordinate system to obtain point cloud data covering the entire welding platform (such as Figure 3 As shown, Figure 3 (in the figure is the point cloud data of the workpiece to be welded);

[0063] Step 4: Calculate the weld path using the point cloud data obtained in step 3; the weld path method is as follows:

[0064] S1, calculate the normal vector of each point in the point cloud; the calculation method is:

[0065] Take several points in the vicinity of any point in the point cloud, fit the plane equation through several points, and get the normal vector n of the plane through the plane equation p , the normal vector of the welding plane is n w ={0 0 1} T , then the normal direction of the point in the point cloud is:

[0066]

[0067] S2, find the point p where the normal vector suddenly changes in the point cloud, and calculate the gradient value of this point; the gradient value is calculated as follows:

[0068] Take several points in the vicinity of any point p in the point cloud and use the following formula to calculate:

[0069]

[0070] Where: p i are other points in the vicinity of point p, g i For point p i Directional derivative with respect to point p;

[0071] Find g for points in the neighborhood i The change in the z direction is the largest (i.e., g i The third component of the point changes the most) and is negative, the g at this point i is the gradient value;

[0072] S3, select multiple points in the gradient direction of point p, and calculate the gradient values ​​of the multiple points one by one by the calculation method in S2, until one of the points changes to zero in the gradient z direction; then the point is the bottom corner point of the groove closest to point p;

[0073] S4, repeating S2 and S3 for multiple times to obtain a number of groove bottom corner points, connecting adjacent groove bottom corner points to obtain two angle tracks of the weld groove bottom;

[0074] S5, take the midline of the two angle tracks at the bottom of the weld groove as the weld track;

[0075] Step 5: Drive the camera 4 to move to the top of the starting position of the weld path through the moving mechanism (i.e., the guide rail 1 and the gantry 2);

[0076] Step 6: Use camera 4 to shoot, and move robot 81 so that camera 4 moves along the weld path to shoot; calculate the welding point for each frame of point cloud data shot, and convert the welding point coordinate system to the world coordinate system; the conversion formula is as follows:

[0077] p w-weld =E t E b E r T 01 T c2 p c-weld

[0078] Where: p c-weld is the coordinate of the welding point in the camera coordinate system; T c2 is the transformation relationship from the camera coordinate system to the robot flange coordinate system; T 01 is the transformation matrix of the flange coordinate system of robot 1 when camera 1 takes pictures; p w-weld The coordinates of the welding point converted to the world coordinate system;

[0079] The coordinates of the welding points in the world coordinate system are stored in a buffer in the memory, and a collection of multiple welding points constitutes a welding path;

[0080] Step 7: When the number of welding points in the buffer reaches a predetermined number (e.g., 50-100), the mobile robot 2 82 is moved to move the welding gun 7 to the welding position for welding (e.g., Figure 2 shown);

[0081] Step 8: Move robot 1 81 and robot 2 82 synchronously, and make camera 1 4 located in front of the moving direction of welding gun 7. Camera 1 4 takes pictures and calculates the welding points, stores them in the buffer, and reads the welding points from the buffer and sends them to robot 2 82 for welding.

[0082] The shooting data of camera 2 5 provides the shooting position to camera 1 4 , and camera 1 4 calculates the precise welding position and guides robot 2 82 to perform welding.

[0083] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit and essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0084] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A dual robot welding method based on laser camera weld tracking, characterized in that: A dual-robot welding device is provided, wherein the dual-robot welding device comprises: A moving mechanism, comprising a guide rail and a gantry mounted on the guide rail and capable of moving along an X-axis direction; A welding unit, comprising a mounting base and a second robot disposed on the mounting base; A visual unit, comprising a robot 1, a camera 1 disposed on the robot 1, and a camera 2 disposed on the mounting base, wherein the field of view of the camera 2 is larger than that of the camera 1; The mounting seat is arranged on the gantry via a rotating shaft and can move along the Y-axis direction, and the rotating shaft can rotate along the Z-axis direction; The second robot is provided with a welding gun; The dual robot welding method comprises the following steps: Step 1: Use the moving mechanism to drive the camera 2 to shoot the welding platform section by section; Step 2: Convert the captured point cloud from the camera coordinate system to the world coordinate system; Step 3: Register and stitch the point cloud converted to the world coordinate system to obtain point cloud data covering the entire welding platform; Step 4: Calculate the weld path through point cloud data; Step 5: driving the camera 1 to move to the position just above the starting position of the weld path through the moving mechanism; Step 6: Use camera 1 to shoot, and move robot 1 so that camera 1 moves and shoots along the weld path; calculate the welding point for each frame of point cloud data shot, and convert the welding point coordinate system to the world coordinate system; The coordinates of the welding points in the world coordinate system are stored in a buffer in the memory, and a collection of multiple welding points constitutes a welding path; Step 7: When the number of welding points in the buffer reaches a predetermined number, the second robot is moved to make the welding gun reach the welding position for welding; Step 8: Move Robot 1 and Robot 2 synchronously, and make Camera 1 located in front of the welding gun's moving direction. Camera 1 takes pictures, calculates the welding points, and stores them in the buffer. At the same time, the welding points are read from the buffer and sent to Robot 2 for welding. The method for calculating the weld path in step 4 is as follows: S1, calculate the normal vector of each point in the point cloud; S2, find the point where the normal vector suddenly changes in the point cloud , calculate the gradient value of this point; S3, select point Multiple points in the gradient direction, and calculate the gradient values ​​of multiple points one by one through the calculation method in S2, until one of the points changes to zero in the gradient z direction; then this point is point The nearest corner point of the bottom of the groove; S4, repeat S2 and S3 to obtain a number of groove bottom corner points, connect adjacent groove bottom corner points, and obtain two angle tracks of the weld groove bottom; S5, take the midline of the two angle tracks at the bottom of the weld groove as the weld track.

2. The dual robot welding method based on laser camera weld seam tracking according to claim 1, characterized in that: The coordinate system conversion in step 2 adopts the following formula: Where: is the point coordinate in the camera's second coordinate system; is the transformation relationship from the camera coordinate system to the rotation axis coordinate system; is the transformation matrix for rotating the Z axis; is the transformation matrix of the Y axis; is the transformation matrix of the X axis; for Convert point coordinates to the world coordinate system.

3. The dual robot welding method based on laser camera weld seam tracking as claimed in claim 1, characterized in that: The calculation method in S1 is: Take several points in the vicinity of any point in the point cloud, fit the plane equation through several points, and get the normal vector of the plane through the plane equation , the normal vector of the welding plane is , then the normal direction of the point in the point cloud is: 。 4. The dual robot welding method based on laser camera weld seam tracking according to claim 1, characterized in that: The calculation method of the gradient value in S2 is: Take any point in the point cloud Several points in the adjacent area are calculated using the following formula: Where: For point Other points in the vicinity, For point With point The directional derivative of Find the points in the neighboring area The point with the largest negative value in the z direction. is the gradient value.

5. The dual robot welding method based on laser camera weld seam tracking as claimed in claim 1, characterized in that: The predetermined number in step seven is 50-100.

6. The dual robot welding method based on laser camera weld seam tracking according to claim 1, characterized in that: In step 6, the welding point coordinate system is converted to the world coordinate system using the following formula: Where: is the coordinate of the welding point in the camera coordinate system; is the transformation relationship from the camera-coordinate system to the robot-flange coordinate system; is the transformation matrix of the flange coordinate system of robot 1 when camera 1 takes pictures; The coordinates of the welding point converted to the world coordinate system.

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