KR20120035969A - Measuring method for delay time between robot motion and welding current for arc sensing - Google Patents

Abstract

The present invention relates to a method for measuring time delay between robot motion welding currents for arc sensing, the method comprising: measuring time delay between robot motion welding currents for arc sensing; A first step of starting the weaving for welding and simultaneously reading whether the weaving index (the point at which the weaving direction changes) is 0 to set an initial reference point after the weaving starts; A second step of checking whether the next weaving index is an even number while starting the weaving welding from the weaving index 0 found through the first step; A third step of continuing the weaving welding until the weaving index becomes an even number after the second step, and starting the data acquisition (DAQ) of the welding current if the even number is even; After the third step, when the next even index is reached, the DAQ is terminated, the noise for the welding current is filtered based on the DAQ, and the secondary curve is obtained by fitting the secondary curve for the welding current, and the welding current is obtained from the obtained secondary curve. Calculating a time point of inflection and calculating a time difference between the inflection points to obtain a time delay; After calculating the position to move to the next index after the fourth step, check whether the end of the weaving welding, and if not the end again to the step of checking whether the weaving index is even after repeating the same process sequentially until the end of the weaving welding It provides a time delay measurement method between the robot motion welding current for arc sensing, characterized in that it comprises a five steps.
According to the present invention, it is possible to implement only by the robot itself without adding a separate measuring equipment, it is possible to measure without considering the characteristics of the welding machine and the robot controller one by one, it can also cope with the noise generated during welding, time delay The effect of minimizing the measurement error on the quantity can be obtained.

Description

MEASURING METHOD FOR DELAY TIME BETWEEN ROBOT MOTION AND WELDING CURRENT FOR ARC SENSING}

The present invention relates to a method for measuring time delay between robot motion welding currents for arc sensing, and more particularly, robot motion-welding current necessary for welding seam tracking using arc sensing of a robot without greatly changing the configuration of equipment. The present invention relates to a method for measuring the time delay between robot motion welding currents for improved arc sensing to accurately and easily measure the time delay between them.

In general, the robot welding machine is a welding robot that performs actual welding, a welding machine that supplies an arc current between the end of the welding robot arm and the base metal, an arc sensor that measures the welding current of the welding machine, and the current measured from the arc sensor. It includes a robot controller for controlling the welding robot by the value.

At this time, the robot takes a weaving motion at the fillet part of the member for arc sensing with the arc sensor, and tracks the position of the welding wire by measuring a change in the welding current generated during the weaving motion.

However, during the weaving operation, the welding current is changed according to the weaving operation, and the robot must know the time delay caused by this phenomenon in order to accurately track the welding line.

Accordingly, in Korean Patent Laid-Open Publication No. 009-0045064, "Arc welding robot control apparatus and method thereof" means for storing welding conditions, weaving motion control means, welding condition change position calculation means, welding condition calculation means, welding condition changing means And the like have been disclosed to make welding line tracking even more accurate.

However, this disclosure technique has to be additionally provided with a separate configuration, and there is a disadvantage that the control and algorithm accordingly.

The present invention was created in view of the above-mentioned drawbacks of the prior art, and the robot motion-welding current for accurately tracking the welding line without significantly changing the basic configuration of the robot welder or adding a new configuration separately. The main purpose is to provide a time delay measuring method between the robot motion welding current for improved arc sensing to improve the welding efficiency and welding quality by measuring the time delay easily and accurately.

The present invention as a means for achieving the above object, in the time delay measuring method between the robot motion welding current for arc sensing; A first step of starting the weaving for welding and simultaneously reading whether the weaving index (the point at which the weaving direction changes) is 0 to set an initial reference point after the weaving starts; A second step of checking whether the next weaving index is an even number while starting the weaving welding from the weaving index 0 found through the first step; A third step of continuing the weaving welding until the weaving index becomes an even number after the second step, and starting the data acquisition (DAQ) of the welding current if the even number is even; After the third step, when the next even index is reached, the DAQ is terminated, the noise for the welding current is filtered based on the DAQ, and the secondary curve is obtained by fitting the secondary curve for the welding current, and the welding current is obtained from the obtained secondary curve. Calculating a time point of inflection and calculating a time difference between the inflection points to obtain a time delay; After calculating the position to move to the next index after the fourth step, check whether the end of the weaving welding, and if not the end again to the step of checking whether the weaving index is even after repeating the same process sequentially until the end of the weaving welding It provides a time delay measurement method between the robot motion welding current for arc sensing, characterized in that it comprises a five steps.

In this case, in the first step, if the weaving index is not 0, the reference point for calculating the time delay cannot be established, so that the step of finding the index 0 while continuing the weaving is further characterized.

In addition, the time delay value obtained in the fourth step is also stored in the memory of the robot controller itself is characterized in that it is used to calculate the average value of the total value.

In addition, the present invention is a method for measuring the time delay between the robot motion welding current for arc sensing; A first step of starting the weaving for welding and simultaneously reading whether the weaving index (the point at which the weaving direction changes) is 0 to set an initial reference point after the weaving starts; A second step of checking whether the next weaving index is an odd number while starting the weaving welding based on the weaving index 0 found through the first step; A third step of continuing the weaving welding until the weaving index becomes an odd number after the second step, and starting a data acquisition (DAQ) of the welding current if the odd number is odd; After the third step, when the next odd index is reached, the DAQ is terminated, the noise for the welding current is filtered based on the DAQ, and the secondary curve is obtained by fitting the secondary curve for the welding current, and the welding current is obtained from the obtained secondary curve. Calculating a time point of inflection and calculating a time difference between the inflection points to obtain a time delay; After calculating the position to move to the next index after the fourth step, and check whether the end of the weaving welding, if not the end again to the step of checking whether the weaving index is odd, and repeating the same process sequentially until the end of the weaving welding It provides a time delay measurement method between the robot motion welding current for arc sensing, characterized in that it comprises a five steps.

According to the present invention, it is possible to implement only by the robot itself without adding a separate measuring equipment, it is possible to measure without considering the characteristics of the welding machine and the robot controller one by one, it can also cope with the noise generated during welding, time delay The effect of minimizing the measurement error on the quantity can be obtained.

1 is an exemplary view showing an example of flat plate weaving for time delay measurement according to the present invention.
2 is a timing diagram showing an example of measuring a robot position command-robot motion-welding current according to the present invention.
3 is an exemplary view defining a weaving index for measuring time delay according to the present invention.
4 is an exemplary configuration block diagram of a robot welder for explaining the present invention.
5 is a flowchart illustrating a time delay measuring method according to the present invention.

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

Figure 1 shows an example of the flat plate weaving welding of the welding torch 100 for the time delay measuring method according to the present invention.

As shown, the welding torch 100 is welded along the welding line 120 while weaving at an angle of approximately 45 ° with respect to the plate member 110.

At this time, the relationship between the robot position command issued to control the welding robot, the robot motion moved by the command, and the welding current that changes depending on the robot motion has the same relationship as in the timing diagram illustrated in FIG. 2.

That is, a time delay of "a" is generated between the robot position command and the robot motion, and a time delay of "b" is generated between the robot motion and the welding current.

Therefore, if the time delay of "a" and "b", that is, knowing these two parameter values, it is possible to accurately track the welding line 120 of the robot according to the weaving welding.

At this time, the time delay of the "a" can be easily obtained by reading the robot encoder value used for the operation of the robot 300 in the robot controller 200 shown in FIG.

However, since the time delay of the "b" is difficult to obtain, various apparatus configurations for obtaining this are conventionally added. However, according to the present invention, a table according to the standard weaving pattern is formed by tabulating the numerical values based on experimental data. You will find a time delay equal to b ".

To this end, in the present invention, as shown in FIG. 1, the welding robot 300 performs welding while performing the weaving motion on the flat plate member 110, and the welding current measured in this process generates a waveform having the same period as the weaving trajectory. By paying attention to the application of this, it is possible to measure the time delay simply and easily, without additional equipment, and to accurately track the welding line 120.

That is, since the welding current has a waveform having the same period as the weaving trajectory, as shown in FIG. 3, the second curve fitting is performed on the welding current measured during one past weaving period at the weaving vertex having an even numbered index. In this case, the obtained secondary curve c has a convex shape upward because only the even-numbered index is curve-fitted.

Therefore, the time difference between the inflection point of the secondary curve c and the vertex position in the weaving trajectory is the amount of time delay as much as "b".

As a result, in the present invention, the average delay time is obtained by repeating the weaving welding several times as described above, and the obtained average delay time is used as a parameter of the algorithm for controlling the arc sensor. It becomes possible.

More specifically, according to the embodiment shown in Figure 5, the time delay measuring method according to the present invention can be made through the following steps.

In the following description, Index refers to a node point reached when weaving from the weaving start point to the end point. The first weaving node point is defined as 0 and the last node point is defined as n. As shown in the illustrated example, it is assumed to end with 9.

In other words, by assigning the node point 0 as index 0, the numbers are sequentially numbered from 0 to 9, the odd and even numbers are alternately displayed, and from the initial weaving to the index 0 and the index 9 from the time delay measurement The value until the end of weaving welding shall be discarded.

In other words, the indices become a reference point for determining time delay (to find an inflection point after the second curve fitting).

Initiate weaving for welding and read if the weaving index is zero.

This is to establish a reference point after the start of the initial weaving.

If the weaving index is not 0, the reference point for calculating the time delay cannot be established, so we continue to find the index 0 while weaving. If the index is 0, start the weaving welding from the index 0 and check whether the next weaving index is even do.

At this time, the concept of weaving continuation includes the process of calculating the node point to move to the next weaving index, which is naturally performed in the robot welding machine, and after each index weaving the index to be weaving, that is, the node point is moved This is the same as the concept of 'the next weaving index calculation' performed after the time delay calculation described later.

As a result, if it is not even number, it will be odd, so weaving weld continues until weaving index is even (2,4,6,8).

In this process, if the weaving index is an even number, the DAQ (Data Acquisition) of the welding current is started simultaneously.

In this case, the DAQ is a kind of measurement system for measuring changes in physical quantities generated during weaving welding.

The DAQ is moved to the next weaving index and continues to the next even index. When the condition is reached, the DAQ is terminated.

That is, when the even numbered index, such as index 2, is reached, the DAQ is performed by moving from index 3 to index 4 with the beginning of DAQ, and when index 4 is reached, noise filtering, secondary curve fitting, Perform inflection point calculation and time delay calculation.

In other words, the noise for the welding current is filtered based on DAQ, and then the secondary curve for the welding current is fitted to obtain the secondary curve (c), and the inflection point of the welding current is calculated from the obtained secondary curve (c). The time delay is calculated by calculating the time difference between the vertices between the even index, that is, the 0th index and the second index, and the time difference between the inflection points obtained from the quadratic curve c.

The time delay calculated in this way is calculated for each even index, and their average value is used as a control parameter.

In addition, after the time delay is calculated, calculate the position to move to the next index, and then check whether the end of the weaving weld, and if it is not the end, return to the step of checking whether the weaving index is even, and then repeat the same process until the end of the weaving weld. Will be repeated.

That is, after the even number check, the time delay for the welding current is continuously calculated until the next even number index, and the value is stored in the memory of the robot controller itself, and the average value of the total value is used as the parameter value.

In addition, in the embodiment according to the present invention, although the second curve fitting is performed using the even index as the reference value, the second curve fitting may be performed using the odd index as the reference value. In this case, however, the curve-fitted secondary curve only has a convex shape downward.

As described above, the present invention describes a method for measuring a time delay to be used as such a control parameter. When the weaving welding is completed after the weaving welding is sequentially moved to the next index, the measuring method of the present invention is finished.

As described above, the present invention can obtain the information value of the time delay as the inflection point of the secondary curve (c) obtained by the secondary curve fitting of the welding current, so that the accuracy of tracking the weld line 120 without additional equipment is improved. It can be increased.

100: welding torch 110: member
120: weld line c: secondary curve

Claims (4)

A method of measuring time delay between robot motion welding currents for arc sensing;
A first step of starting the weaving for welding and simultaneously reading whether the weaving index (the point at which the weaving direction changes) is 0 to set an initial reference point after the weaving starts;
A second step of checking whether the next weaving index is an even number while starting the weaving welding from the weaving index 0 found through the first step;
A third step of continuing the weaving welding until the weaving index becomes an even number after the second step, and starting the data acquisition (DAQ) of the welding current if the even number is even;
After the third step, when the next even index is reached, the DAQ is terminated, the noise for the welding current is filtered based on the DAQ, and the secondary curve is obtained by fitting the secondary curve for the welding current, and the welding current is obtained from the obtained secondary curve. Calculating a time point of inflection and calculating a time difference between the inflection points to obtain a time delay;
After calculating the position to move to the next index after the fourth step, check whether the end of the weaving welding, and if not the end again to the step of checking whether the weaving index is even after repeating the same process sequentially until the end of the weaving welding Method for measuring the time delay between the robot motion welding current for arc sensing, characterized in that it comprises a five steps.
The method according to claim 1;
In the first step, if the weaving index is not 0, the reference point for calculating the time delay cannot be established, so that the step of finding the index 0 while continuing the weaving is further performed. The robot motion welding current for arc sensing Time delay measurement method.
The method according to claim 1;
The time delay value obtained in the fourth step is stored in a memory in the robot controller itself and used to calculate the average value of the total value, the time delay measurement method between the robot motion welding current for arc sensing.
A method of measuring time delay between robot motion welding currents for arc sensing;
A first step of starting the weaving for welding and simultaneously reading whether the weaving index (the point at which the weaving direction changes) is 0 to set an initial reference point after the weaving starts;
A second step of checking whether the next weaving index is an odd number while starting the weaving welding based on the weaving index 0 found through the first step;
A third step of continuing the weaving welding until the weaving index becomes an odd number after the second step, and starting a data acquisition (DAQ) of the welding current if the odd number is odd;
After the third step, when the next odd index is reached, the DAQ is terminated, the noise for the welding current is filtered based on the DAQ, and then the secondary curve is obtained by fitting the secondary curve for the welding current, and the welding current is obtained from the obtained secondary curve. Calculating a time point of inflection and calculating a time difference between the inflection points to obtain a time delay;
After calculating the position to move to the next index after the fourth step, and check whether the end of the weaving welding, if not the end again to the step of checking whether the weaving index is odd, and repeating the same process sequentially until the end of the weaving welding Method for measuring the time delay between the robot motion welding current for arc sensing, characterized in that it comprises a five steps.

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