KR20070006026A - Machine vision system and method for automatic data gathering do hull forming process - Google Patents

Abstract

A laser vision system for curved main plates and a method for embodying the same are provided to suggest real dimensional values such as three-dimensional shape information of a welding surface as well as a gap between the curved main plates, a thickness of a welding member, a distance between the welding surface and a front end of the sensor, and a three-dimensional slope for the welding member by using a non-contact type laser vision sensor as a welding line tracking sensor for one-side welding of curved main plates. A laser vision system for curved main plates comprises: an image processing module which comprises a CCD camera, a laser diode, an optical band pass filter and a spatter protection glass to capture an instantaneous image in which a trigger signal is inputted from a welding motion controller; a calculation module for calculating characteristic values through operation with a projection matrix after detecting and tracking a welding line of the curved main plates, and detecting a gap between main plates, a thickness of a member, a slope of a curved surface, and a height value between the member and a welding carriage; a filtering module for reducing an influence due to an error and mis-detection for resulting values continuously processed by a trigger; and a communication module for communicating with the motion controller.

Description

Machine vision laser vision system and its implementation {Machine vision system and method for automatic data gathering do hull forming process}

1 is a view showing an embodiment of a curved disk laser vision system according to the spirit of the present invention.

2 is a flowchart representing an image processing algorithm according to the spirit of the present invention.

3 is a flow chart for finding a laser center in accordance with the teachings of the present invention.

4 to 6 are views for calculating a characteristic value according to the spirit of the present invention.

<Explanation of symbols for main parts of the drawings>

101: curved abacus laser vision system 102: rotary torch

103: weaving torch

The present invention relates to a curved sheet laser vision system and a method of implementing the same.

At present, in the shipbuilding industry, the process of grain processing for the manufacture of hull shell plating is essential. Ships are largely manufactured through cold working using presses and hot working using gas torches. In particular, the demand for automation for the hot working process, which is fully dependent on the skilled workers' work experience, has led to a great deal of research at home and abroad. However, it is still not clearly identified or fully automated.

 In the present situation, where the processing process is mostly done by hand, the first step for automation is to make knowledge of field workers' experience. However, there are so many conditions in the field, such as the amount of oxygen in the gas torch, the properties of propane gas, member shape, thickness, size, cooling method, etc. It is true.

In particular, welding techniques vary greatly from operator to operator, so manual welding is less repeatable and consistent. Among them, manual welding is frequently performed in fields such as shipbuilding or bridges where the ratio of butt welding is high.

In particular, from the viewpoint of reducing the total cost of the welding process, the speed of short to long single-sided welding should be increased. However, the automation of the welding process is limited to a straight plate, which is a good condition for working, and in the case of a curved sheet plate, automation is not achieved. In more detail, in the case of the curved plate, welding is almost performed several times manually according to the thickness of the welding member by using one-sided welding, but welding automation is essential. However, the conventional contact sensor detects the shape of the three-dimensional welding line. Due to the difficulty and noise caused by the welding flame, it is difficult to accurately track the weld line.

Therefore, automation of welding is essential to improve productivity and cost and to ensure high quality welding. Recently, a vision system using a laser, which is a non-contact sensor, is used as a welding line tracking sensor. However, due to the vulnerability in the welding environment due to image noise, etc., it is not properly utilized.

 Therefore, in order to automate welding, an on-site data collection system is required to collect data on the heating position and heating speed, the shape of the member, and the movement trajectory by the gas torch, which is recognized as the most important data during the machining process. Do.

In order to solve the above problems, the present invention uses a non-contact laser vision sensor as a welding line tracking sensor for curved welding on one side of a curved plate (2 electrodes), as well as a gap between the curved plate as well as three-dimensional shape information of the welding surface. , The thickness of the member, the distance between the surface to be welded and the front end of the sensor (Z), the three-dimensional inclination with respect to the welding member, and the like, in order to present the real dimension (mm).

In addition, an object of the present invention is to recognize the shape of the welding member in the curved plate to automatically detect the start and end of the welding to help the motion controller to manage the welding schedule.

In addition, the present invention implements a function of automatically recognizing the start position and the end position of the welding operation from the shape information of the laser strip, and the average filter and Kalman to provide reliable data for the various data calculated by the system The purpose is to implement a robust filter technique using a filter.

According to an aspect of the present invention for achieving the above object, comprising a CCD camera, a laser diode, an optical bandpass filter, a spatter protection glass, for capturing the moment image when the trigger signal is input from the welding motion controller An image processing module, a calculation module for detecting and tracking a welding plate of curved plate, a gap between the plate, a thickness of a member, a slope of a surface, a height value between a member and a welding carriage, and calculating a characteristic value through calculation with a projection matrix; It is possible to provide a curved plate laser vision system including a filtering module for reducing the effects of errors and misdetections on the result values continuously processed by the trigger and a communication module for communicating with the motion controller.

Here, the CCD camera and the laser diode is characterized in that the separation angle of 10 degrees to 50 degrees. In addition, the resolution of the captured image the moment the trigger signal is input from the welding motion controller is characterized in that it is set to 640 * 480.

 According to another aspect of the present invention, when generating a trigger signal in the welding motion controller, capturing an image in the image controller, binarizing the captured original image to a threshold of 255, calculating a laser center, maximum Calculating the thickness of the weld base material by calculating the distance value from the gap position point to the laser main line perpendicularly, calculating the gap information between the weld base materials, calculating the slope value of the laser main line, and joining Calculating a height value of the center position point and the junction center position point, a real dimension transformation step of converting the pixel units of the position values into a real unit of mm, and an error about the result values continuously processed by the trigger; Provides a method for implementing a curved sheet laser vision system including data filtering steps to reduce the effects of false detections can do.

The calculating of the laser center may include scanning and storing an object having a predetermined thickness in the vertical direction while scanning from the left side of the image to the center pixel, and 10 pixels in the + and − directions from the vertical position of the stored object. Repeating the method performed in the first step including resetting the scan area to find the laser center in the horizontal direction to the last horizontal scan position and scanning from the right side to the center pixel of the image. And a second step of finding the center.

In addition, the slope value of the laser main line is

It is characterized by calculating using an equation. Also, the distance value from the maximum gap position point to the laser main line

It is characterized by calculating using an equation.

Through the present invention, it is possible to detect single-sided weld line information (welding line data, gap information, member thickness, transverse inclination of the weld face relative to the weld line travel direction, weld face height), and the weld line is in the direction of the laser vision system. Welding line information can be detected even when tilted in three dimensions (ROLL, PITCH, YAW). In addition, the use of the laser shape for the start and end of the welding can help in scheduling the welding operation. In addition, it can provide reliable data by processing the data through the average filter and the Kalman filter. In addition, since there is a trigger mode and an offline mode by a system timer, an automatic processing function of an image processing algorithm can be implemented without an external trigger.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments set forth below, and the scope of the invention will be presented by the addition, limitation, deletion, addition, etc. of components within the scope obvious to those skilled in the art to which the present invention pertains. Could be.

1 is a view showing an embodiment of a curved disk laser vision system according to the spirit of the present invention.

Referring to FIG. 1, the curved sheet laser vision system is applicable to a two-electrode welding carriage for curved sheet single side welding. More specifically, the present invention system 101 is a laser vision system 101 consisting of a laser diode and a CCD camera as shown in Figure 1 is mounted at the tip of the welding progress direction to provide welding line related information, and then Rotary torch 102 and weaving torch 103 are formed on the carriage being moved to the rail.

The present invention consists of a CCD camera, a laser diode, an optical bandpass filter, a sputter protection glass, and the CCD camera and the laser diode have a separation angle of 25 degrees. Also, the resolution of the image is set to 640 * 480. Image capture operation is performed by trigger mode.

The present invention does not use a contact welding seam tracking sensor, which is a single-sided welding automation technology, which is mainly used in the conventional art, and tracks weld lines on a three-dimensional curved surface of a curved plate in a non-contact manner, as well as a gap between the abacus ( Gap), the thickness of the member, the distance between the surface to be welded and the front end of the sensor (Z), the three-dimensional tilt of the welding member, etc. provides a laser vision system (Laser Vision System). Using the laser vision system algorithm, a trigger signal generated from a curved plate welding motion controller (hereinafter referred to as a motion controller) is transmitted to the laser vision system controller, and a single image is captured to detect and track a curved sheet weld line. Characteristic values are calculated by detecting the gap between the abacus, the thickness of the member, the surface slope (shape), and the height between the member and the welding carriage, and then calculating them with the projection matrix, which is the result of the previous calibration. Calculate The communication with the motion controller uses a method in which characteristic values calculated by RS-232C communication are transmitted according to a trigger input signal.

2 is a flowchart representing an image processing algorithm according to the spirit of the present invention.

Referring to FIG. 2, the present invention is largely composed of a preprocessing module (image processing module) and a post processing (calculation and filtering module), and each frame sequence is processed by a trigger signal. Processes performed in the pretreatment module and the post-processing module are as follows.

When the welding motion controller 201 generates a trigger signal, the image controller enters a trigger mode to capture one image (S202). The captured original image is binarized at a threshold of 255 as shown in Equation 1 (S203).

여기서, T = 255

Where T = 255

As described above, the trigger signal generated by the curved plate welding motion controller (hereinafter referred to as the motion controller) is transmitted to the laser vision system controller, and a single image is captured to detect and track the curved plate weld line, as well as the gap between the plate plates. The thickness curve of the member (shape), the height value between the member and the welding carriage are calculated in real time and transmitted to the welding motion controller through RS-232C communication, followed by the rotating torches and weaving torches that follow. It's a way of welding.

3 is a flow chart for finding a laser center according to the spirit of the present invention.

Referring to FIG. 3, the laser center is searched in two stages (S302). In the first step, an object having a predetermined thickness (about 7 pixels) of the laser in the vertical direction is scanned while scanning from the left (0 pixel) to the center pixel (320 pixel) of the image (S304) and stored (S305). The scanning area is reset by 10 pixels in the + and − directions of the stored vertical position (S306), and the laser center is found up to the last horizontal scan position in the horizontal direction (S307). Similarly, in step 2, the search is performed from the right (640pixel) to the center pixel (320 pixel) (S302), and the laser center is found by the method performed in the first step (S304). Here, the reason for searching from the left and right directions of the image is that the noise on the left and right sides of the image is less than the center vicinity due to the image noise caused by the spatter and the fume during welding.

Referring to FIG. 4, the thickness of the welding member may be calculated using Equation 2 from the length of the vertical line dropped on the line connecting the point 404 and the point 405 at the maximum gap position point 403. After finding the laser center using the algorithm shown in FIG. 3, the left end point 402 and the right end point 401 of the laser are used to find two home points 404 and 405 by using Equation 2 below. Calculate

The laser main line is then detected and the maximum gap point 403 having the maximum distance value between the line and the previously detected laser center is searched for. Here, the gap point 403 is limited to a predetermined range (15 <range (pixel) <50) to a value corresponding to the member thickness. First, the point 404 calculates the line information connecting the left end point 402 of the laser and the maximum gap point 403 by using Equation 2 above, and from the position point having the largest vertical distance from the line to the laser center. You can find it. Similarly, the point 405 can also be detected from the position where the vertical distance from the line connecting the right end point 401 of the laser to the laser center at the maximum gap position point 403 is the largest. In order to calculate the thickness of the welding base material, the distance value from the maximum gap position point 403 to the point which is perpendicular to the laser main line may be calculated by using Equation 3.

It can be seen that the gap information between the welding base material is a distance value between two points 406 and 407. First, in the case of the point 406, a position point having a maximum distance value between the laser centers from the line connected with the maximum gap point 403 at the point 404 previously detected can be obtained. Can be found from the point at which the distance to the laser center is maximum on the line connecting the maximum gap point 403 at point 405.

Referring to FIG. 6, the characteristic value calculation in FIG. 2 may be performed (S208). The slope value 601 of the laser main line is calculated using Equation 2, the junction center location point 605 is calculated using Equation 3, and the height of the junction center location point that was previously calculated The value (distance value between the member surface and the sensor) 604 can likewise be calculated by the distance calculation formula (2).

The real-dimensional transformation process step S209 of FIG. 2 is a process of changing the pixel unit values of the previous position values in mm units, and the converted value is 3 * 4, which is a result of the camera calibration process in Equation 4. It is obtained by calculation with the projection matrix. Here, the slope 601 of the laser line, the gap data 602, the thickness of the welding base material 603, the weld line data 605, the height 604 between the welding surface and the front end of the laser vision system, etc., in mm unit values. Is calculated.

The data filtering step (S210) of FIG. 2 is an average filter expressed as shown in Equation 5 in order to secure the reliability of the data by reducing the influence of errors and misdetection on the result values continuously processed by the trigger. The Kalman Filter, which is a stochastic dynamic estimation technique expressed by Equation (6) and Equation (6), is applied.

 Camera Calibration:

Mean-Filter:

Kalman-Filter:

Referring to Figure 5, the welding line laser strip at the start and end point is a flat base material is shown in a straight line form 502, during most single-sided welding operation appears in the same shape as (501) to recognize the laser strip shape Automatic detection of welding start and end points allows the motion controller to assist in the scheduling of welding operations. The layout of the system program of the present invention is shown in FIG. 6, and an automatic test function using a system timer is implemented as well as a camera calibration operation without an external trigger.

Through the present invention, it is possible to detect single-sided weld line information (welding line data, gap information, member thickness, transverse inclination of the weld face relative to the weld line travel direction, weld face height), and the weld line is in the direction of the laser vision system. Welding line information can be detected even when tilted in three dimensions (ROLL, PITCH, YAW). In addition, the use of the laser shape for the start and end of the welding can help in scheduling the welding operation. It also provides reliable data by processing the data through the average filter and the Kalman filter. In addition, since there is a trigger mode and an offline mode by a system timer, an automatic processing function of an image processing algorithm can be implemented without an external trigger.

Claims (7)

An image processing module including a CCD camera, a laser diode, an optical band pass filter, and a spatter protection glass, for capturing an instant image of a trigger signal input from a welding motion controller; A calculation module that detects and tracks the curvature weld line, the gap between the abacus, the thickness of the member, the slope of the surface, the height value between the member and the welding carriage, and calculates the characteristic value through calculation with the projection matrix; A filtering module for reducing the influence of errors and false detections on the result values successively processed by the trigger; And A communication module for communicating with a motion controller; Abacus laser vision system comprising a. The method of claim 1, The CCD camera and the laser diode are curved plate laser vision system, characterized in that having a separation angle of 10 degrees to 50 degrees. The method of claim 1, The resolution of the captured image the moment the trigger signal is input from the welding motion controller is set to 640 * 480 curve vision laser vision system. Capturing an image in an image controller when generating a trigger signal in the welding motion controller; Binarizing the captured original image to a threshold of 255; Calculating a laser center; Calculating the thickness of the weld base material by calculating a distance value from the maximum gap position point to the laser main line in a vertical line; Calculating gap information between the weld base metals; Calculating an inclination value of the laser main line and calculating a height value of the junction center location point and the junction center location point; A real-dimensional conversion processing step of converting the pixel units of the position values into mm units which are real dimensions; And A data filtering step for reducing the influence of errors and misdetections on the result values successively processed by the trigger; Curved plate laser vision system implementation method comprising a. The method of claim 4, wherein Computing the laser center Scanning from the left side of the image to the center pixel, finding and storing an object having a predetermined thickness in the vertical direction, and resetting the scan area by 10 pixels in the + and-directions from the vertical position of the stored object to the last in the horizontal direction. A first step comprising finding the laser center to a horizontal scan position; And a second step of finding the laser center by repeating the method performed in the first step while scanning from the right side to the center pixel of the image. The method of claim 4, wherein The slope value of the laser main line is

A method for implementing a curved disk laser vision system, characterized in that the calculation using a formula. The method of claim 4, wherein The distance value from the maximum gap location to the laser main line

A method for implementing a curved disk laser vision system, characterized in that the calculation using a formula.

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