KR100189090B1 - Sensor structure for welding line inspector - Google Patents

Abstract

The present invention relates to a structure of a visual sensor that improves the performance of the laser sensor, that is, the welding sensor for visual tracking using rotation of the laser and the cylindrical lens. The laser band projected from the laser (1) and the cylindrical lens (2) Reflected to the fixed mirror 6 by a rotating mirror 3 equipped with a motor 4 and an encoder 5 so as to rotate in the middle, and the laser strip reflected back from the fixed mirror 6 is projected onto the welding line. The principle is to reduce the volume of the sensor, and to change the transmission angle or to form the position of the laser strip to move the position of the laser strip to measure the shape of the weld in the welding direction.

Description

Vision sensor structure for welding seam tracking

1 is a conceptual diagram of a visual sensor for welding seam tracking of the present invention.

2 is a conceptual diagram of the rotation operation of the present invention laser strip.

3 is an image processing time sequence of a rotating laser strip of the present invention.

4 is a view showing the synthesis of images by the visual sensor of the present invention.

5 is a conceptual diagram of a conventional visual sensor for tracking seam tracking.

6 is a view illustrating the synthesis of images by a conventional visual sensor.

* Explanation of symbols for main parts of the drawings

1: laser 2: cylindrical lens

3: rotating mirror 4: motor

5: encoder 6: fixed mirror

The present invention relates to a structure of a visual sensor that improves the performance of the welding sensor tracking visual sensor using the laser project, that is, the rotation of the laser and the cylindrical lens.

The structure of a conventional visual sensor is formed using a laser project (laser 21 + cylinder type lens 22) to form a long strip on the welding line as shown in FIG. 5, and passes only the laser. The optical band filter 24 is mounted and the CCD camera 23 fixed to the relative angle α is used to photograph the shape of the band and to extract it using an image processing algorithm. The figure shows an image 25 of a laser strip 26 scanned on an I-improved weld, wherein the relationship between the laser strip and the image projected on the actual substrate is determined by the condition that the weld line is on the laser projection surface and from the camera model. Triangulation is used to calculate the position of the weld line.

On the other hand, the welding seam can be traced by moving the welding torch to the measured position. In this case, the position of the welding seam is determined, and it is not possible to determine the inclination or shape of the welding seam. If it is curved or three-dimensionally formed, there is a disadvantage in that it is not easy to cope with the change in shape.

In addition, since the resolution is increased by increasing the separation angle between the laser and the camera, in order to increase the resolution, the distance between the sensor and the laser is increased, and thus the sensor volume is increased, and when the separation angle is increased, the height control is particularly necessary. In welding, there were problems such as a blind spot (shadow effect) that could not be measured by the sensor or a deviation of the measurement range.

In general, a welding line tracking visual sensor is used to automate welding, and a welding line tracking requires a sensor that is small and capable of accurately, accurately and quickly obtaining a lot of information about the welding line.

The visual sensor for welding seam mainly adopts the active technique, because it is possible to easily obtain the specific position information of the welding seam in the state of blocking natural light and acrylic light. The method of acquiring the weld information using a passive visual technique for a large part of the method and the method of acquiring the weld information from multiple locations required using multiple laser projects can be repeated.

Therefore, the present invention can change the measurement position by automatically rotating the laser strip in order to solve the above-mentioned conventional problems, even if the weld line is curved or formed three-dimensionally, The position and shape were created to enable simultaneous measurement.

Hereinafter, the configuration and the effect of the present invention will be described in detail with reference to the accompanying drawings.

1 is a conceptual diagram of a vision sensor for welding seam tracking according to the present invention, and FIG. 2 is a conceptual diagram illustrating a rotation operation of the laser strip of the present invention.

Reflected to the fixed mirror 6 by a rotating mirror 3 equipped with a motor 4 and an encoder 5 so that the laser strip projected from the laser 1 and the cylindrical lens 2 can rotate in the middle. In order to reduce the volume of the sensor and to automatically change the angle of transmission or to measure the shape of the welding part in the welding progress direction, the laser band re-reflected from the fixed mirror 6 is projected onto the welding line. to be.

Reference numeral 7 denotes a CCD camera, and 8 an optical band filter.

According to the present invention, the rotation mirror 3, in which the motor 4 is mounted, is periodically rotated in the positive or negative angular directions (Δθ, 2Δθ, .....), and the actual laser position L is achieved. The laser strip 9 projected at is reflected by the rotating mirror 3, as shown in FIG. 2, and is reflected back to the fixed mirror 6 fixed at an angle of β, and is projected onto the welding line when the welding line travels. Will move back and forth from (9a, 9b, 9c).

In other words, the effect of the laser strip 9 'rotating (2Δθ, 4Δθ, .....) at the virtual laser position L' is equivalent to automatically adjusting the angle between the laser and the camera during the operation of the sensor. By changing the range of the measurement field, it is possible to prevent the shadow effect of the visual sensor from the weld inclined in the height direction or the deviation of the measurement position from the measurement range. The size of the sensor can be reduced, and the effect of obtaining a plurality of laser bands in the direction of the welding line can be obtained, unlike in the conventional art. Can be determined. Therefore, the welding posture can be changed and set in advance correspondingly.

Using the encoder (5) mounted on the rotating mirror (3) it is possible to know the angle of rotation of the mirror, thereby knowing the virtual laser rotation angle and the relationship between the virtual laser position (L ') and the image from the visual sensor By using the angle between the camera and the laser (separation) (α, α-2Δθ, α + 2Δθ, .....) by the optical triangulation method, three-dimensional information is obtained at each position of the welded portion where the laser strip exists. Can be calculated

The time sequence for obtaining the image of each of the laser beams being rotated may be represented by a pulse train at each step as shown in FIG.

When the angle of the rotating mirror is r, the CCD camera captures the image of the laser strip (10a), and reads the image (image) at a time synchronized with the position of the rotating mirror on the image board and stores it in the memory buffer 1 (11a). .

At this time, the laser is separated from the background image using a high pass filter using the threshold of the laser, and the laser location is searched using a laser search algorithm, and the coordinates are stored in the memory.

After acquiring the image of the memory buffer 1, the image of the laser band projected at different rotation angles is recaptured by the CCD camera (10b) and stored in the memory buffer 2 (11b).

In the same manner, it is possible to determine the position of the laser strip at each position where the rotation angle is changed (11c and 11d).

It can also be synthesized with one period (T) (image synthesis).

In the same way, image capture 10a ', ........ and image memory 11a', .......... are continuously possible at the position changed in the weld line direction.

FIG. 4 shows the shape of the synthesized image 12 to grasp the three-dimensional shape around the weld. The laser strip 13a-d of the synthesized image shows the three-dimensional shape (direction, Tilt) can be determined and processed by scanning images from different angles to cope with the missing information, and the information of overlapping measurement positions can be grasped at the same time by the deformation of the structure during welding.

Therefore, the present invention can change the measurement position by automatically rotating the laser strip, it is possible to reduce the volume of the sensor and to measure the position and shape of the welding line at the same time, even in various changes of the welding line, that is, curved or three-dimensional shape It created a new concept in seam tracking.

Claims (1)

Reflected to the fixed mirror 6 by a rotating mirror 3 equipped with a motor 4 and an encoder 5 so that the laser strip projected from the laser 1 and the cylindrical lens 2 can rotate in the middle. In order to reduce the volume of the sensor and automatically change the angle of transmission or to measure the shape of the weld in the welding direction, the laser band re-reflected from the fixed mirror 6 is projected onto the welding line. A visual sensor structure for welding seam tracking.