JPS60247476A - Method for controlling robot - Google Patents

Abstract

PURPOSE:To teach a robot adapted to a positional error by adding the information on the discrimination of check points with respect to the check points in teaching data to teaching position data and storing the data. CONSTITUTION:A weld line WL2 is subjected to teaching at the check points Pc11-Pc20 and at points Pa11-Pa14 except said poits. The check locus CL retreated by a specified distance from the position data at all the teach points stored in a storage device is calculated. A torch is moved along the locus CL and the position data of the weld line WL2 is actually measured at every check point. The actually measured position data at the check points Pc11-Pc20 collected in the above-mentioned manner is used in place of the stored position data. The position data at the other points Pa11-Pa14 is corrected by using such data, by which the welding is executed while the deviation of the weld line is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a robot control method, and more particularly to a teaching method that is adaptable to workpiece dimensional errors of industrial robots.

[Background of the invention]

Figure 1 shows an example of an automatic welding device using an industrial robot, where 1 is the industrial robot, 2 is its arm, and 3 is the arm 2.
4 is a conduit for guiding welding wire, carbon dioxide gas, etc. to the torch 3. The industrial robot 1 has multiple degrees of freedom, such as driving the arm 2 back and forth, up and down, and lateral directions, and bending the wrist at the tip of the arm 1. Reference numeral 5 denotes a workpiece to be welded, which is fixedly positioned on a positioner 6. FIG. 2 is a block diagram of a control device for a playback type industrial pot used for this purpose, in which 11 to 13 are servo devices corresponding to each axis of the industrial robot, 14 is an arithmetic control device,
15 is a storage device.

To briefly describe the operating method of such an automatic welding machine, during teaching, the operator gives position commands to the servo devices 11-13 via the arithmetic and control device 14't, and drives each axis of the robot to turn the torch. The position is determined, the position data at that time is stored in the storage device 15, and a series of operations are memorized using this procedure. During playback, the arithmetic and control device 14 sequentially reads out the position data in the storage device 15, performs processing such as interpolation calculations, gives a position command to the servo device 1i-ia, drives the torch 3, and performs processing such as interpolation calculation. Do the work in question.

In such an automatic welding machine, the trajectory of the torch 3 is determined by the industrial robot (industrial robot) l according to the position data in the memory device ft15.
faithfully reproduced within the accuracy of However, the position of the welding line on the workpiece 5 to be worked on is not at the same position as during teaching due to positional errors of the positioner 6, installation errors of the workpiece 5 to the positioner 6, dimensional errors of the workpiece 5, etc.
Due to such positional errors of the welding line, the quality of welding performed by such an automatic welding machine is so low that it cannot be put to practical use.

[Purpose of the invention]

One object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide a robot teaching method that can adequately accommodate the above-mentioned position errors. That is, it is an object of the present invention to provide a teaching method that allows teaching work to be performed easily, in a short time, and without requiring any skill.

[Summary of the invention]

One feature of the control method of the present invention is that it includes a servo device, a storage device for storing all required data, and an arithmetic control device that supplies work data to the storage device and gives position commands to the servo device. (robots using the Kutsuku method)
In teaching when controlling, if the teaching data is a check point, check point identification information is added to the teaching position data and stored, the actual position data is measured during playback, and the data is stored in the storage device. The purpose of the robot is to correct the position data stored in the robot and control the robot.

[Embodiments of the invention]

Next, the present invention will be explained in detail regarding a welding machine using the drawings. FIG. 3 is an explanatory diagram showing an example of a welding line detector, in which 21.22 is a welding base metal, 23 is a torch, 24.25 is a pair of base metal detectors, and both base metal detectors 24.25 are , when it is detected that it is the optimal position with respect to the base materials 21 and 22,
The torch 23 connects the welding line 2 at the joint between the base materials 21 and 22.
A welding line detector 26 is arranged at an optimum position relative to the welding line detector 7. Therefore, this weld line detector 2
6 to position the torch 23 at the optimum position and take in the position data of each axis of the robot at that time, it is possible to convert the welding line 27 to each axis of the robot and actually measure the next position data.

Hereinafter, the welding line position data converted to each axis will be simply referred to as welding line position data.

Next, an example of a method of controlling an automatic welding machine equipped with such a welding line detector 26 will be described. Figure 4 shows the work procedure for welding lines.

Is the origin of the robot determined within a certain range of space, and is it a welding torch? 3 is positioned at this origin, it means that the robot Fi is at the origin. Welding line WL represented by a thick line
Memorize I in the robot at teach points pal to pa6,
Separately, the robot has an evacuation point Ptx+Pt before and after welding work.
zK memorize it.

The welding work is performed using the playback method. After starting from the origin PG and passing through the point PiI, the torch is passed along the welding line WLI memorized at the teaching points Pa1 to Pa6. 3 to perform welding work. Pass through that retreat point Ptzt to the original origin PO
Return to In this way, the work is taught to start from the origin and return to the origin, and this is called 1 work rate.

FIG. 4 shows the case where there is no check point in this work unit, but next, the case where there is a check point in FIG. gg5 will be explained. Note that the check point is a teach point whose position data should be actually measured using a weld line detector or other means. The moral tangent WL2 shown by the thick line is the check point P
Ct1~PC1G and points other than check points Pa1l~
Taught at Pa1t, separate evacuation point P to *P
tsa is being taught. In this case, during playback operation, all teaching points of welding + wIWL2 stored in the memory device 5 PCII ~ PCRO
% Pnxs ~ From the position data of Pat4, welding line W
Retract a certain distance from L2 and calculate a nine-check trajectory CL. First, starting from the origin Poo, move the torch 23 along this check trajectory CL, and use the welding line detector 26 at each check point. The position data of welding line WL2 is actually measured. However, PCI+'~PC! When this check work is completed for all of the check locus CL of 0', it returns to the origin via the escape point ptu.

Check point PC1 collected through check work here
1--Use the actually measured position data of the PC 20 in place of the position data of the check points p C11 to lPc*o stored in the storage device 15, and use these actually measured position data to check the other points Pa1l to Pa14. By making corrections to the stored position data, etc., the position of the stored welding line WL2 is actually measured and the deviation from the position of the welding line of the workpiece to be welded is corrected, and then the torch 23 is turned on again. Origin 1'
Move in the order from oo to P'l1gPC11 and perform welding while accurately tracing the welding line WL2. Figure 6 is a diagram for explaining the method of correcting the positional deviation of the welding line using the above-mentioned actually measured position data, where WLt indicated by the broken line is the welding line that has been taught, and the position of the check point actually measured by the checking operation is pci , // ~ PC20", connect P C1t" r P Ctx to form line segment L1, connect P Cpg" and P C14" to form line segment L2, and then obtain the actual measured position data. The actual welding line WLak can be found from .

As is clear from the above description, whether or not the checking operation is necessary, the path for storing and hiding the storage device 151C may be a path along the welding line only 7'CI times.

If there is no check point in the route, welding is performed in one operation, and if there is a check point, the check trajectory is calculated, the check operation is performed while moving along the check trajectory, and the teaching is performed in the second time. After correcting the point position data, welding work is performed. That is, the only difference between the two in the teaching wait is whether or not some of the teaching points are taught to be check points.

FIG. 7 is a flowchart of the control method described above, in which the arithmetic and control unit 14 causes the position inspection work and welding work using a torch to be performed in this order.

That is, block 28 checks whether the position of the welding torch has returned to the predetermined origin within the work area.

The block 29 stores teaching data for one working desk (for example, the teaching line WL2 shown in FIG. 5) from the self-storage device 15.
An example of each work unit is shown in Figure 9. ) is read out.

Block 30 is for determining whether or not there is a check point in the workpiece. If there is no checkpoint, that is, for the workpiece shown in FIG. 4, the process proceeds to block 38.

Block 31 is a check trajectory (pctt' shown in FIG.
~PC20') position data is calculated.

Block 32 is for driving the torch along the check trajectory calculated in block 31.

In block 33, when the torch advances from the origin (Pool) and reaches a predetermined point (for example, Pill), it is determined whether or not it is a check point (in this case, the process proceeds to block 35). Information is given as shown in FIG. 9a, which will be explained in detail later.

Block 34 is for actually measuring position data using a sensor, in which case the sensor is placed at the position shown in FIG. 801. Note that 02 is the welding position of the sensor.

Block 35 is for determining whether or not the work on the workpiece has been completed in one work table.

Block 36 is for checking whether the torch has returned to its original position upon completion of the position inspection work.

Block 37 contains actually measured position data (PCI shown in FIG.
I"~PC*O") is used to modify the teaching data (WLa)k in the storage device 15.

Block 38 is for carrying out workpiece bathing.

Block 39 is for checking whether the torch has returned to its original position upon completion of the welding work.

The arithmetic and control unit 14 performs the steps of blocks 28 to 39 to perform a series of work operations.

FIG. 9(a) is a diagram showing teaching data and work data in a storage device according to an embodiment of the present invention. In the figure, "servo device each axis position data" is the X-axis servo at the teaching point,
This is a position command value for the Y-axis servo and 2-axis servo.

Of course, if the robot has multiple axes such as the wrist rotation axis, position command values for those axes are also included here. "Arc" is the power on/off information for welding. The "check point" is information indicating that the entire position data of the actual welding line of the workpiece to be currently welded is a point to be actually measured during playback according to the procedure explained in FIG.

"Corner point" is information indicating that the teaching point given by the teaching data is the intersection of two straight lines.

These “arcs” 8 “check points” and “corner points”
The information such as the above is information indicating the attributes of the teach point, and may be independent bit information, or may be encoded information in which part or all of the information is encoded. "Peripheral device control information" includes synchronization number 48 and other control #J information for peripheral related devices such as a positioner (FIG. 1, 6) or a belt conveyor that operates in conjunction with the robot.

As is clear from the above explanation, according to the present invention, as information indicating the attributes of a teach point, information for identifying whether or not the teach point is a fault at a check point is included in all work data and stored in the storage device. Therefore, when the teach point is identified as a check point, the position is inspected and the teach point position data and related teach point position data such as corner points are corrected as necessary, and then welding is performed. Is it possible to install a positioner or compare work? The taught welding line, which is caused by various factors such as positioning error of the mounting table, installation error of the workpiece on the seventh table, dimensional error of the first workpiece, or positioning error of the robot, and the actual welding work. Top welding can be performed with positional errors with the weld line corrected, and an automatic welding machine with good appearance and welding strength can be obtained.

Further, according to the present invention, since any point can be specified as a check point, it is possible for the operator to memorize sufficient position data of In11 degrees during teaching, such as the inside or back side of a box-shaped structure. K is designated as a check point when the workpiece is a rotating part or a workpiece with different dimensions, but can sufficiently accommodate dimensional changes during position inspection work. As above, high-quality welding can be obtained as well as the time required for teaching work can be significantly shortened, and the teaching work can be made extremely easy.

〔Effect of the invention〕

According to the present invention, since the attribute of the taught position data is added to identification information at the time of teaching, it is possible to perform control according to the nucleus attribute at the time of playback.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an example of an automatic welding machine, Fig. 2 is a block diagram of an industrial robot's fi (IJ control device), Fig. 3 is a welding line detector, Fig. 8F44, Fig. 5, Fig. 6 is a diagram for explaining the control method according to the present invention, FIG. 7 is a flow diagram of the control method according to the present invention, FIG. 8 is a diagram showing the position of the torch,
FIG. 9 is a diagram illustrating teaching data and work units created in one embodiment of the present invention. l...Industrial robot, 2...Arc 1.3...
Welding torch, 4... Conduit, 5... Workpiece, 6
...Positioner, 11-13...Servo device, 14
... Arithmetic control device, 15... 1 device, 21 River base material, 22... Base material, 23... Welding torch, 24...
Parent phase detector, 25... Base metal detector, 26... Welding line detector, 27... Welding line. 3rd verse 40 O 5th day 7th note (α) 7th te>

Claims (1)

[Claims] 1. Servo device, storage device for storing required teaching data,
and an arithmetic and control device that supplies work data to the storage device and gives position commands to the servo device, and in a control method for a robot controlled by a playback method, check point identification information is added to check points in the teaching data. A method for controlling a robot, characterized by storing the data as position data.