KR100859335B1 - Tracking method for welding start-point using lvs and visual servoing - Google Patents

Abstract

A welding starting-point tracking method using LVS(Laser Vision System) and visual servoing is provided to minimize an error of the welding starting-points and further improve operating stability by applying a visual servoing concept to the LVS, thereby tracking welding starting-points continuously and fixedly maintaining the posture of a robot. A welding starting-point tracking method using LVS and visual servoing comprises: an LVS image obtaining step of receiving coordinates of a robot such that the LVS obtains images(S203); a robot tool end moving step of adding proper increments to the coordinates of the robot such that the LVS recognize bottom face, side faces, and a front face in a welding block through the obtained images, and moving a position of the robot tool end such that a robot tool end maintains a predetermined distance relative to a recognized face in the bottom face, the side faces, and the front face in the welding block; and an LVS starting-point calculating step of calculating a starting point of the LVS using information on the bottom face, the side faces, and the front face in the welding block recognized by the LVS.

Description

Tracking method for welding start-point using LVS and visual servoing}

1A and 1B are flowcharts illustrating a welding start point tracking method using a conventional elves.

2 is a conceptual view illustrating a welding start point tracking method using a conventional elves.

3 is a flowchart illustrating a welding start point tracking method using the LV and the visual servoing according to the present invention.

4 is a conceptual diagram illustrating the embodiment shown in FIG. 3.

The present invention relates to a welding start point tracking method using LVS and Visual Servoing.

With the recent development of robot technology, vertical articulated six-axis robots are also used in the welding field. A welding torch and a gun are attached to the tool tip of the 6-axis articulated six-axis robot, and the robot's wrist has the ability to rotate in two or three axes, and in the case of three axes, yaw, twist, and tilt are generally similar to the human wrist. ), Pitch, Bend, Roll, Twist, etc. This configuration performs welding as if it were a human welding.

At this time, the welding is performed at a position in consideration of the torch orientation and the torch distance of the working angle and the transfer angle to suit all the welding postures.

In order to perform welding using such a robot, it is important to track the welding start point in advance before the welding operation. In particular, the tracking of the welding start point in the all-limited welding block is necessary to prevent and track the collision between the robot and the welding member. In connection with a variety of problems, such as preventing time delays, more accurate and faster tracking methods are required.

Conventionally, in order to find a welding start point using such a robot, it has been previously required to grasp the spatial coordinates of the welding start point previously taught to some extent. Referring to FIG. 1A to FIG. Under the premise of knowing the typical teaching point, take a posture for sensing the floor surface and find the floor surface by moving in the -z direction from the path of ① to ② (S101). If the bottom surface is found, a point on the bottom surface is found (S103). On the basis of the found point, after maintaining a certain distance in the z direction from the bottom surface is moved as in ③ (S105). In order to find two points on the bottom surface, the two points are repeatedly searched three times to obtain six points (# 1, # 2, # 3, # 4, # 5, and # 6) (S107).

Next, after changing to the posture for sensing the side, and moving in the + y direction in the path ④ to ⑤ to find the side (S109). If a side is found, a point on the side is found (S111). After maintaining a certain distance in the y direction from the side on the basis of the found point it moves in the + x direction toward the front in the path of ⑥ to ⑦ (S113).

Then, moving in the + x direction on the space to find the edge, where the edge refers to the welding line (S115). If an edge is found, find a point corresponding to the edge (S117), move to maintain a certain distance from the weld line based on the found point (S119), find the first corner point (# 7) (S121), Subsequently, as shown in ⑧, a certain distance is moved in the -z direction (S123), and the second corner point (# 8) is found (S125).

Subsequently, a plane equation of the bottom surface is generated with the information of six points (# 1, # 2, # 3, # 4, # 5, # 6) on the floor surface (S127), and the first corner point (# 7) and A straight line equation of the corner is generated using the information of the second corner point (# 8) (S129). Then, the intersection coordinates are obtained from the plane equation of the bottom surface and the linear equation of the corner (S131). Finally, the intersection coordinates are stored as a starting point (S133).

However, using the conventional welding start point tracking method using the conventional elves caused the following problems in order to track the welding start point in the welding block.

First, unlike the case of finding the welding start point in the open space, since the laser band is located in the direction of movement of the welding robot, many restrictions are placed on the attitude of the robot to avoid collision between the robot and the welding member during sensing. There was this.

Second, if the robot recognizes the welding member and then transmits the welding member information to the robot controller, the controller of the robot can determine the spatial position of the welding member based on the received information. Since the information of various images cannot be transmitted to the controller of the robot, there is a problem that the location of the welding start point must be tracked using only very limited information.

In addition, except for the above two problems, the conventional welding starting point tracking method must grasp the information about the rough welding starting point in advance, and various posture changes are required to track the welding starting point. A lot of time was required for the inconvenience.

In order to solve the above problems, the present invention applies a visual servoing concept to an LV to track a welding start point in a continuous motion, and keeps the robot's posture fixed to minimize the error in the tracking start point. The technical task of this method is to provide a welding start point tracking method using LVS and visual servoing.

According to the spirit of the present invention for achieving the above technical problem, in the welding start point tracking method using the LVS (LVS) to find the welding start point in the welding block and the visual servoing, a) transmitting the coordinates of the end of the robot tool Acquiring an image of the elves to acquire the image of the elves; b) an appropriate increment value is applied to the coordinates of the robot so that the LS recognizes all the bottom, side, and front surfaces of the welding block through the acquired image, and at the same time, the elves among the bottom, side, and front surfaces. A robot tool end moving step of moving the robot tool end in space such that the robot tool end maintains a predetermined distance with respect to the recognized surface; And c) an elves start point calculation step of calculating an eleven point starting point of the elves using information of the bottom, side, and front surfaces of the welding block recognized by the elves. We provide a welding start point tracking method using S and visual servoing.

At this time, the step b) is, in the Z direction to the coordinates of the end of the robot tool when the elves do not recognize both the bottom surface, the side surface or the front surface through the obtained image b-1-1) An LV coordinate coordinate storing step of adding an appropriate increment value and storing the coordinates of the LV coordinate; b-2) a robot tool end movement step of transmitting the stored coordinates of the LV to the robot to move the position of the end of the robot tool; And b-3) iteratively acquiring the image of the el VB to receive the modified coordinates of the robot to re-acquire the image.

In addition, in step b), when the BSL recognizes only the bottom surface through the acquired image, b-1-2), an appropriate increment value is applied to the X coordinate of the robot coordinates and the Y coordinate of the robot. An EL coordinate coordinate storage step of storing the applied Y coordinate and the Z coordinate of the bottom surface recognized by the EL BS as the coordinates of the EL BS; b-2) a robot tool end movement step of transmitting the stored coordinates of the LV to the robot to move the position of the end of the robot tool; And b-3) iteratively acquiring the image of the el VB to receive the modified coordinates of the robot to re-acquire the image.

In addition, in step b), when the BSL recognizes only the bottom surface and the side surface through the obtained image b-1-3), the X coordinates to which an appropriate increment value is applied to the X coordinates among the coordinates of the robot. And storing the Y coordinate of the side recognized by the LV, and the Z coordinate of the bottom surface recognized by the LV, as the coordinates of the EL BS. b-2) a robot tool end movement step of transmitting the stored coordinates of the LV to the robot to move the position of the end of the robot tool; And b-3) iteratively acquiring the image of the el VB to receive the modified coordinates of the robot to re-acquire the image.

In order to fully understand the present invention, the advantages of the present invention, and the objects achieved by the present invention, reference should be made to the accompanying drawings in which preferred embodiments of the present invention are illustrated.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the drawings, FIG. 3 is a flowchart illustrating a welding start point tracking method using an LV and visual servoing according to the present invention, and FIG. 4 is a conceptual diagram illustrating the embodiment shown in FIG. 3. .

Referring to FIG. 3 and FIG. 4 in parallel, a preferred embodiment of the welding start point tracking method using the LV and visual servoing according to the spirit of the present invention, first, the spatial position of the robot tool (Tool) of the robot A step S201 of obtaining the coordinates Prx, Pry, Prz, Rry, Rrp, and Rrr is included. The robot of the present embodiment is a six-axis robot and has coordinates on six degrees of freedom. In the coordinates of the robot (Prx, Pry, Prz, Rry, Rrp, Rrr), 'Prx' is 'Depth', 'Pry' 'horizontal', 'Prz' 'vertical', 'Rry' 'yaw', 'Rrp' 'pitch', 'Rrr' 'roll' Corresponds to Here, the coordinates of the robot (Prx, Pry, Prz, Rry, Rrp, Rrr) refer to the coordinates of the robot tool tip (TCP).

Thereafter, the method transmits a signal to acquire the image by transmitting the robot coordinates to the LS (S203). ELV is a generic term for a laser vision system (LVS) that includes a photoconductor for scanning laser light and a camera for imaging the scanned laser light. Additional explanations are omitted.

And acquiring an image from the LCD.

Next, a step (S207) of determining the image obtained through the elves. In this case, the images that can be acquired in the elves are divided into four types, and when looking at the detailed steps for each type, first, when the nothing is visible on the elves image (S221) And, secondly, when only the bottom surface is recognized on the elves image (S225), and thirdly, if only the bottom and side surfaces are recognized on the elves image (S229), Finally, it is classified into step S209 when both the bottom surface, the side surface and the front surface are recognized on the LCD image.

First, in step S221 when nothing is shown on the elves image, an appropriate increment in the Z direction to the coordinates (Prx, Pry, Prz, Rry, Rrp, Rrr) of the robot is indicated as in ① of FIG. Values are stored as coordinates (Plx, Ply, Plz, Rly, Rlp, Rlr) of values, resulting in Plx = Prx, Ply = Pry, and Plz = Prz-offset.z (offset Z-direction increment). Value), Rly = Rry, Rlp = Rrp, and Rlr = Rrr.

And the coordinates (Plx, Ply, Plz, Rly, Rlp, Rlr) of the stored elves includes the step (S241) transmitted to the robot. Thereafter, the robot moves the robot tool end to the transmitted elves coordinates (S243), and the coordinates of the moved robot tool end position are transmitted to the elves again (S201) and are commanded to acquire an image (S203). ) Is repeated.

Second, the step (S225) in the case where only the bottom surface is recognized on the elves image is recognized by coordinates (Prx, Pry, Prz, Rry, Rrp, Rrr) and elves of the robot as shown in ② of FIG. Using the coordinates of one point on the floor (Pex, Pey, Pez, Rey, Rep, Rer), it is stored as the coordinates of Elves (Plx, Ply, Plz, Rly, Rlp, Rlr). As a result, Plx = Prx , Ply = Pry + offset.y, Plz = Pez, so that the X direction is saved as the coordinate of the robot tool, the Y direction is saved as the proper increment value to the coordinate of the robot tool tip, and the Z direction is about the recognized floor. Stored in the coordinates of the floor recognized to maintain a constant distance.

The coordinates (Plx, Ply, Plz, Rly, Rlp, and Rlr) of the elves are transmitted to the robot (S241). Then, the robot moves the end of the robot tool to the transmitted elves coordinates (S243). The coordinates of the end position of the robot tool thus moved are transmitted to the LS again (S201), and the command (S203) is repeatedly performed to acquire an image.

Third, in the case where only the bottom surface and the side surface are recognized on the elves image (S229), the coordinates (Prx, Pry, Prz, Rry, Rrp, Rrr) and elves of the robot are as shown in FIG. Save as coordinates of PLS (Plx, Ply, Plz, Rly, Rlp, Rlr) using coordinates (Pex, Pey, Pez, Rey, Rep, Rer) of the intersection of the recognized floor and side As a result, Plx = Prx + offset.x, Ply = Pey, Plz = Pez is modified so that the X direction is a coordinate that adds an appropriate increment value to the coordinates of the robot tool tip, and the Y and Z directions are recognized floors and sides. Store the coordinates of the floor and side recognized to maintain a constant distance to.

The coordinates (Plx, Ply, Plz, Rly, Rlp, and Rlr) of the elves are transmitted to the robot (S241). Then, the robot moves the end of the robot tool to the transmitted elves coordinates (S243). The coordinates of the end position of the robot tool thus moved are transmitted to the LS again (S201), and the command (S203) is repeatedly performed to acquire an image.

Finally, when both the bottom surface, the side surface, and the front surface are recognized on the elves image (S209), the elbow is shown as ④ of FIG. 4 by using respective information corresponding to the bottom surface, side surface, and front surface. Since the starting point of the S can be calculated, the step S211 of calculating the starting point of the elves is performed.

The start point of the elves calculated as described above is transmitted to the robot (S213), and then the welding start point of the robot is calculated (S215).

Referring to Figure 4, it will be described with a simple example to understand the welding start point tracking method using the LS and the visual servoing according to the spirit of the present invention.

 The area shown in FIG. 4 is an inner space of the welding block, and the bottom surface, the side surface, and the front surface are formed to be substantially perpendicular to each other. First, the robot poses to track the starting point of welding, and then approaches toward the bottom as shown in ①. If the bottom is visible while approaching, the robot approaches the side by maintaining a proper distance from the bottom as shown in ②. Then, if the bottom and the side is visible at the same time, as shown in ③ to maintain a certain distance with respect to the bottom and the side approaches to the front. Afterwards, if the front side is detected as in ④, the robot stops. Therefore, unlike the conventional method, the robot actively tracks a welding start point through sensing of the elves on the bottom surface, the side surface, and the front surface.

Although the present invention has been described with reference to the embodiments shown in the accompanying drawings, it is merely an example, and those skilled in the art will understand that various modifications or equivalent other embodiments are possible therefrom. will be.

Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

The welding start point tracking method using the present invention is a visual servoing concept that takes a long time to track the welding start point due to each partial operation (face finding, welding line finder, etc.) that is conventionally performed excessively many times. By applying this, it is possible to continuously track the welding starting point continuously without having the individual partial motion or the special target image, thereby improving the operational efficiency.

In addition, the welding start point tracking method using the present invention in the present invention, when the coordinates of the current robot is transmitted to the elves, the elves determine the movement coordinates of the robot after comparing the coordinates of the image and the acquired robot. By virtue of the limited robot's operation by the limited information, it has a technical effect that can provide improved stability to the changeable working environment.

In addition, the welding start point tracking method using the present invention LV and visual servoing has a technical effect of reducing the error of the tracked welding start point by maintaining the position of the robot fixed.

Claims (4)

In the welding starting point tracking method using LVS and visual servoing to find the starting point in the welding block, a) elb image acquisition step of receiving the coordinates of the robot to obtain an image of the elves; b) Applying an appropriate increment value to the coordinates of the robot so that the LS recognizes all the bottom, side and front surface of the welding block through the acquired image, and recognizes the recognized surface among the bottom, side and front surfaces. A robot tool end movement step of moving the position of the robot tool end so that the robot tool end maintains a constant distance; c) an elves start point calculation step of calculating an elves' start point using information of the bottom, side, and front surfaces of the welding block recognized by the elves. Welding start point tracking method using LVS and visual servoing. The method of claim 1, Step b), b-1-1) If the elves do not recognize the bottom surface, the side surface, or the front surface through the acquired image, an appropriate increment value in the Z direction is added to the coordinates of the end of the robot tool, and the Storing an LV coordinates to store the coordinates of the BS; b-2) a robot tool end movement step of transmitting the stored coordinates of the LV to the robot to move the position of the end of the robot tool; And b-3) receiving the modified coordinates of the robot re-acquisition of the elves image re-acquisition of the elves Vs image; characterized in that it comprises a, Welding start point tracking method using LVS and visual servoing. The method of claim 1, Step b), b-1-2) When the ELV recognizes only the bottom surface through the acquired image, the X coordinate among the coordinates of the robot, the Y coordinate which has been appropriately added to the Y coordinate of the robot, and the ELV. An elves coordinate storing step of storing the Z coordinate of the bottom surface recognized by the elves as coordinates of the elves; b-2) a robot tool end movement step of transmitting the stored coordinates of the LV to the robot to move the position of the end of the robot tool; And b-3) receiving the modified coordinates of the robot re-acquisition of the elves image re-acquisition of the elves Vs image; characterized in that it comprises a, Welding start point tracking method using LVS and visual servoing. The method of claim 1, Step b), b-1-3) When the LV recognizes only the bottom surface and the side surface through the acquired image, the X coordinate which has applied an appropriate increment value to the X coordinate among the coordinates of the robot, An Y coordinate storage step of storing a Y coordinate of a side surface and a Z coordinate of a bottom surface recognized by the elves as the coordinates of the elves; b-2) a robot tool end movement step of transmitting the stored coordinates of the LV to the robot to move the position of the end of the robot tool; And b-3) receiving the modified coordinates of the robot re-acquisition of the elves image re-acquisition of the elves Vs image; characterized in that it comprises a, Welding start point tracking method using LVS and visual servoing.

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