JPS58143982A - Control system of robot - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a robot position control method using a teaching play pack method.

The conventional control method for welding robots, painting robots, etc. is to position a predetermined part of the robot's wrist at a teaching point, store the position information of each axis of the robot in VC as teaching data, and then Based on the data, each axis of the robot is controlled so that the tip of the robot wrist follows a desired trajectory.

However, with such conventional control methods, even when welding workpieces of the same shape, for example, due to workpiece setting errors by the positioner, the teaching point taught for the previous workpiece and the teaching point of the currently set workpiece may differ. Because of the misalignment, it was not possible to weld using the same teaching data, and re-teaching was therefore required. Furthermore, when performing multilayer welding, teaching was required for each layer. In addition, when teaching the second and subsequent layers in multi-layer welding, it is necessary to teach while assuming the welding state up to the previous layer, making accurate teaching difficult.

The present invention has been made in view of the problems mentioned above, and eliminates the need for re-teaching when moving the locus of a predetermined part of the wrist in parallel, reduces teaching time, and enables multilayer welding with high welding accuracy. The purpose is to provide a control method for a robot capable of welding.

According to this invention, the position information of each axis of the robot when a predetermined part of the robot wrist coincides with the teaching point is stored in advance in a storage device, and the stored value of this storage device is changed by a predetermined value. The locus drawn by a predetermined portion of the robot wrist is moved in parallel by a predetermined amount.

In addition, the position information of each axis of the robot when a predetermined part of the robot wrist coincides with the teaching point is stored in advance in the storage device, and the deviation between the trajectory that the predetermined part of the robot wrist should draw and the predetermined part of the robot wrist is detected. and controlling each axis of the robot so that a predetermined part of the robot's wrist follows the trajectory to be drawn based on the stored value of the storage device and the output of the detection means, By correcting the stored value in the storage device based on the above, and changing the corrected stored value by a predetermined value, the locus drawn by a predetermined portion of the robot wrist is translated in parallel by a predetermined amount.

FIG. 1 is a system configuration diagram of a robot to which the present invention is applied, and shows a special VL melt-fitting robot. This welding robot (1) is composed of a welding robot main body 11, a welding robot control device 2, a field operation panel 8, a teaching box 4, a welding power supply device 5, and a welding wire box 6. The welding robot main body 1 has a wrist 7 and a horizontal feed (
(X), horizontal (Y), and vertical (Z) orthogonal coordinate systems, and the position of each part is controlled by control signals from the welding robot control device 2. The welding robot main body IVc is also equipped with a welding wire feeding device f8.
The welding wire 9 is supplied from the welding wire box 6 to the wrist 7 by the welding wire box 6. 1fc1 Fry ear 9
An appropriate welding power source is supplied from the welding power supply device Fi, 5 according to a Rano command from the welding robot control device 2. The field operation panel 3t is operated as appropriate by the operator VC, and has switches for selecting the operation mode of the welding robot main body 1, emergency stop, return to origin, etc. The teaching box 4f'i has switches for moving each part of the welding robot body 1, switches for writing position information of teaching points into the bath welding O-bot control device 2, and the like.

FIGS. 2(a) and 2(b) show a plan view and a side view of the wrist 7 of the welding robot 1, respectively.

This hand 17 has a rotation axis S for rotating the wrist 7 in the X-Y plane and a rotation axis B for rotating the welding torch 10 in the Y-2 plane. The direction of the welding torch 10 (the posture of the wrist) is controlled by controlling the moving axis B by the welding robot control device 2.

FIG. 3 is a block diagram showing an embodiment of a robot control method according to the present invention. Central processing unit (CPU)
) 11 is the teaching data (XX Y, Z,
θB, θB). Here, a case will be described in which multilayer welding is performed based on this teaching data.

First, welding of the first layer is performed based on pre-stored teaching data and the output of the arc current sensor 12. C
Outputs the movement command value for each axis from the PUIIFi teaching data. Note that each axis (X,
Since the YXZ, SX, and B axes are controlled in the same way, only the control of one axis, L/1, will be explained below. CPUII
The movement command value outputted from is latched by the latch circuit 13 and applied to the pulse distributor 14.

The pulse distributor 14 outputs a pulse signal to a subtractor 15V (to move at a pre-specified speed based on the movement command value. Note that the pulse signal has a large number of pulses when the speed is fast, and a large number of pulses when the speed is slow). The number of pulses is small.Also, while the robot is stopped, the number of pulses fluctuates within the range of ±1 pulse.The other input of the subtractor 15 is the encoder 16.
A number of pulse signals corresponding to the moving distance of the shaft, that is, the amount of rotation of the shaft drive motor 7 are added to the subtracter 15, and the deviation of the two human power signals is taken by the subtractor 15 and calculated as the position side 5 difference. Leads to counter 8. The count value of the position deviation counter 8 corresponds to the number of deviation pulses between the value specified by the pulse distributor 14 and the robot's current position, and this count value is converted into an analog signal by the D/A converter 19. Add to subtractor 2(). An analog signal corresponding to the rotational speed of the shaft drive motor 7 is added from the L speed detector 21 to the other input of the subtracter 20.
Of'j2 The deviation of the human power signal is taken and guided to the shaft drive motor 7 via the servo amplifier 22.

In addition, 2 arc current sensors are used to trace the welding torch tip so that it follows the actual welding line during robot operation, and output the correction information (movement command value for each axis) to the above → Novo thread (not shown), welding. Control the tip of the torch V).

In this way, the first layer of multilayer welding is welded. In addition, since welding can be performed using the arc current sensor 2 and the welding torch can be controlled to follow the correct position, it is possible to weld on the actual welding line even if the teaching point is not accurate.

1゜Meanwhile, during welding of the first layer, the deviation (correction data) (△Ei) between the welding line A and the actual welding line B is taught for a certain length △t) as shown in the 41st line. The launch circuit 23, 24, 25 latches each axis and connects it to CP.
It is stored in the memory in U11.

In addition, the squared equation of the correction data (Ei), t\Ei”
=△h; ix”+△g i y! 10△E I Z R
This satisfies the following, and the memory of CPU 11, the first
It is stored like a table.

Table 1: In addition, correction data (6g 4 / ) between the taught locus A and the actual welding line B for a certain period of time (mut) as shown in Figure 5 is broken down into each axis and stored. The integrated value of this correction data is nothing but the positional misalignment between the actual welding line and the trajectory based on the teaching data.

Therefore, the teaching data on the welding line can be calculated based on the teaching data previously stored in the CPU II and the correction data stored during the 11th # contact.

Next, teaching data on the welding line corrected by the welding ff of the second and subsequent layers and the correction data is used. Here, we will explain the case in which the welding center of the second layer is separated from the welding center of the first layer by a distance (△1+> VC in the −Y direction) as shown in FIG. In this case, the movement amount setter 26 (FIG. 8) K is set in advance to parameters corresponding to the distance between the welding centers of the 11th layer and the second layer (XtN'lt%zt), xl=0, yt=- △t1, Z t= 0 becomes 1.bu,
Before starting the second weld, the parameters are output from the setting device 26 to the CPU II in this movement 1.
Ru.

CP' [71, 1t, i: This parameter is calculated as 7t (respectively, each teaching data If on the welding line that was 14 at the time of welding IJ 17th) At this point, I will focus on the rest of the group and carry out the second layer of bathing.

Similarly, when welding the 8th layer so that the welding center is separated from the welding center of the 1st layer by a distance (△tx) in the -Z direction, the movement amount setting device should be set before welding the 8th layer. From 26, the parameter jl(Xts >'Is zt), xt=
O,)rj=o,zt--△t.

All you have to do is make it output. Incidentally, when welding the second and subsequent layers, the arc current sensor 12 is made inactive, and the tracing control of the torch tip is not performed.

In this way, the weld center distance between each weld layer can be set to a desired distance, making it possible to perform multilayer welding with high welding accuracy.

Further, the present invention is not limited to multilayer welding, and for example, as shown in FIG. 7, during teaching, the teaching point is set to P. →
pH→P1! If the currently set welding line of the workpiece changes from PIG' to P11'PIt' due to a setting error caused by the positioner, only the first teaching points p and o' will be taught. However, for other teaching points, the vector quantity A(P
,. P. ′ ), there is no need for re-teaching, and the teaching time can be shortened.

In this embodiment, an arc current sensor is used to perform tracing control, but the present invention is not limited to this, and any sensor that can detect a weld line may be used. 1st order,
In this example, we explained the application to a welding robot, but it can also be applied to a machining robot, a painting robot, etc. Furthermore, the method of determining the coordinate system of the robot body, the number of controlled axes, etc. are limited to this flIvC. Not done.

As explained above, according to the present invention, by changing the pre-stored teaching data by a predetermined amount, the locus of a predetermined part of the robot wrist can be easily translated in parallel, which makes it necessary to re-teach VLL. It is possible to reduce the operator's teaching work and time. In addition, when performing multi-layer welding, the welding of the first layer uses a sensor to memorize the trajectory when the welding tip is controlled to the correct position, and the welding of the second and subsequent layers uses the sensor to memorize the trajectory of the first layer. Since this is carried out by moving the locus in parallel, it is possible to perform multi-layer welding with high welding accuracy.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram of a robot to which the present invention is applied, FIGS. 2(a) and 2(b) are a plan view and a side view of the wrist of a welding robot, and FIG. 3 is a system configuration diagram of a robot to which the present invention is applied. A block diagram showing an example of the control method of the robot involved. Figures 4 and 5 are diagrams showing the relationship between the teaching trajectory and the actual welding line. Figure 6 shows multi-layer fillet welding. The sectional view, FIG. 7, is a relationship diagram between a teaching point and a teaching point obtained by moving this teaching point in parallel. 1. Robot body, 2. Welding robot control device, 8
...On-site operation panel, 4...te, each bonox,
7... Wrist, 11... Central processing unit, 12... Arc current sensor, 14... Hals distributor, 1b... Encoder, 17... Shaft drive motor, 18... Position deviation counter, 26...Movement amount setting device. Figure 1

Claims (2)

[Claims] (1) The position information of each axis of the robot when a predetermined portion of the robot wrist coincides with the teaching point is stored in advance in a storage device, and the predetermined portion of the robot wrist follows a predetermined trajectory based on the stored values in the storage device. VC [: I In the control method of the robot that controls each axis of the bot, by changing the stored value of the storage device by a predetermined value, the trajectory drawn by the predetermined part of the robot wrist is changed by a predetermined amount. A control method for a robot characterized by moving the robot in parallel. (2) Store in advance the position information of each axis of the robot when a predetermined part of the robot wrist coincides with the teaching point.
t, and controls each axis of the robot so that a predetermined part of the robot wrist draws a predetermined trajectory based on the stored value in the storage device. A detecting means for detecting a deviation from a predetermined part of the robot wrist is provided, and the predetermined part of the robot wrist follows the trajectory to be drawn based on the stored value of the storage device and the output of the detecting means. In addition to controlling each axis of the robot, the values stored in the storage device are corrected based on the output of the detection means, and the corrected and stored values are changed by a predetermined value to draw a predetermined portion of the robot wrist. A robot control method whose characteristic is to move the locus in parallel by a predetermined amount.