JPH056218A - System for controlling industrial robot - Google Patents

Abstract

PURPOSE:To enable correct work to be conducted even when there is less dispersion in working shapes or positionings by preventing a product out of a standard from advancing to at following process and being mixed with a successful product or preventing erroneous work from being executed in the process to the various kinds of works having different shapes. CONSTITUTION:The operating path of an end effector fitted to the wrist top of a robot is programmed so as to be directed from a teaching position P1 to a teaching position P2, in the case of detecting the generation of signals for specifying the execution of work from a sensor fitted to the end effector or the peripheral device of the robot, the end effector is directed to the next teaching position P3 after executing the operation to be executed at the teaching position P2 when the position is apart from the teaching position P1 for more than a distance set in advance and the end effector does not arrive at the teaching position P2 and in the other case, the end effector is directed to a teaching position P4 set in advance after outputting abnormal output signals set in advance.

Description

Detailed Description of the Invention

[0001]

[Industrial application] When the shape of the work to be assembled and processed by the industrial robot varies or the work has an error in positioning, it is possible to perform the work by automatically changing the regenerative motion of the robot. Control system for industrial robots.

[0002]

2. Description of the Related Art Conventionally, as a control system for this type of industrial robot, there has been one as shown in an explanatory view of the robot control system in FIG. 9 (Japanese Patent Laid-Open Nos. 57-113116 and 57-113115). ). In summary, a detector is attached in the vicinity of a moving part of a robot or a movement path of the robot, a detection signal from the detector is detected, and a moving operation is stopped immediately or after a predetermined distance. The robot control method is characterized in that the robot hand is moved to the next target position after performing the work to be performed at the target position that was sometimes heading.

Further, the above-mentioned conventional technique is disclosed in JP-A-57-113.
More specifically, referring to FIG. 9 disclosed in Japanese Patent Publication No. 116, the robot control method is such that the robot operation is taught in advance, and the robot operation is executed in accordance with the teaching data. Includes a position command for moving the robot hand from the current position P ₁ to the second target position P ₃ via the first target position P ₂ , and the robot hand is moved from the current position P ₁ to the first target position P ₁ . it is moved to P _2, where although the target of the work is moved from there if it is detected in the second target position P _3, mounted during the movement to reach the first target position P _2, for example, the robot hand When a predetermined signal that regulates the robot movement is generated, such as when the detected detector contacts the target work, it is detected and the movement of the robot hand is immediately detected. There is stopped after operating a predetermined distance (L _0), for example, operations such as to grip the workpiece, the robot hand ignoring the remaining travel from its rest position until the first target position P ₂ This is a robot control method in which the robot is moved to the second target position P ₃ .

[0004]

However, in the above-mentioned prior art, in the case where a product which is out of the standard or different kinds of works having different shapes are mixed, the shape of the work itself or the positioning of the work. In the case where there are variations, there has not yet been developed a means for correctly judging and processing them.
Therefore, in the above-mentioned conventional technology, a non-standard product proceeds to a subsequent process and is mixed with an acceptable product, or an erroneous work is performed on the work of different types having different shapes in the process, There has been a problem that it is not possible to correctly deal with a non-regular situation in which the work is rejected despite the mere variation in the shape or positioning of the work.

Therefore, the object of the present invention is to prevent variations in the shape of the work itself, positioning of the work, etc.
If it is within the allowable range, the work position is automatically changed according to those variations, or if the variation is outside the allowable range, it should be notified to external peripheral equipment and workers, and it should be done there. By automatically performing the work, the non-standard product may go to the subsequent process and be mixed with the acceptable product, or the wrong work may be performed on the work of different types having different shapes. It is an object of the present invention to provide a control method for an industrial robot, which prevents the occurrence of damage and works correctly even when there is some variation in the work shape and positioning.

[0006]

In order to achieve the above object, the present invention is a robot control system for reproducing a program taught in advance based on a work program, which is an end effector attached to the tip of the wrist of the robot. Is programmed so as to move from the teaching position P1 to the teaching position P2, and while the end effector is being moved from the teaching position P1 to the teaching position P2, a work is executed from a sensor attached to the end effector or a peripheral device of the robot. When the generation of the specifying signal is detected, if the position is away from the teaching position P1 by a preset distance or more and does not reach the teaching position P2, the teaching position P
After performing the operation to be performed in step 2, the teaching position P3 is moved to the next teaching position P3, and in a case other than the above case, a preset abnormal output signal is output and then the teaching position P4 is preset. An industrial robot control system is provided to solve the above problems.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the present invention will be described in detail with reference to the attached FIGS. 1 is a block diagram of an arc welding system that realizes an embodiment of the present invention, FIG. 2 is an explanatory diagram of an operation program taught to a robot according to an embodiment of the present invention, and FIG. 3 realizes the embodiment of FIG. FIG. 4 is an explanatory diagram of the robot operation within the allowable range according to the embodiment of FIG. 2, and FIG. 5 is an explanatory diagram of the robot operation when the welding length is shorter than the allowable range according to the embodiment of FIG. 6, FIG. 6 is an explanatory diagram of a robot operation when the welding length is longer than an allowable range according to the embodiment of FIG. 2, FIG. 7 is an explanatory diagram of a teaching locus of a conventional robot, FIG. 8 is a program diagram of a conventional robot operation, FIG. 9 is an explanatory diagram of a conventional robot control method.

In FIG. 1, reference numeral 1 is a robot, and a welding torch 2 is attached to the tip of the wrist as an end effector, and a sensor head 3 for detecting the joint shape of a work 4 is attached to the welding torch 2. 6 is the sensor head 3
The robot controller 5 is a sensor controller that controls whether the joint shape of the workpiece 4 can be detected.
Send to. The robot controller 5 sends a signal representing the state of the robot to the central controller 7. The central control unit 7 controls a plurality of robot control units. For example, when an abnormality occurs in a certain robot, by lighting a lamp, it is possible to determine what kind of abnormality has occurred in which robot. It informs the operator or outputs an abnormal signal to a higher-level control device.

In the example of the conventional teaching locus of the robot shown in FIG. 7, the teaching operation of the robot will be described. A series of straight lines with arrows represent the teaching locus for the work 42.
The robot 1 adopts a teaching playback method. Further, since the robot control device 5 has a linear interpolation function, a teaching point is not necessary in a portion operated by a straight line, and a point of changing the operation direction (here,
Only P0, P1, P2, P3) need be taught.
Further, for example, when the robot is to perform arc welding work, the programmable general-purpose output signal of the robot controller 5 is connected to the input circuit for generating the arc of the arc welding machine, A general-purpose output signal is sent to the position in the operation program where you want to start arc welding.
It is sufficient to record a command for N, and record a command for turning off the general-purpose output signal at a position where the arc welding is to be ended. In the example of FIG. 7, a command for turning on the general-purpose output signal is recorded at the teaching position P1, and a command for turning off the general-purpose output signal is recorded at the teaching position P2. In addition, various commands are recorded at each teaching position so that the robot can perform various tasks, and can be reproduced during automatic operation. FIG. 8 shows an operation program of such a robot.

Industrial robots are often used in the field of performing work on the same type of work, but in this case, the work shapes are the same and the relative positional relationship between the robot and the work is all plural work. The same is a prerequisite. This is because the teaching-playback type robot repeats the motion of teaching.

However, depending on the type of the work, there are cases where the shape of the work does not require so much accuracy, and the accuracy of the jig for fixing the work is not good, so that the above-mentioned preconditions can be maintained. It can be difficult. Even in such a case, the purpose of automation is to increase the precision of the work shape more than the precision required by the product,
Further, it is not preferable to make a highly accurate jig because it leads to an increase in the cost of the product itself and an increase in the cost of the production equipment.

Against this background, a robot and a sensor have been combined in recent years to provide an adaptive function such as correcting the reproduction position on the robot side even when the accuracy of the work shape or the accuracy of the jig is not good. Production systems have been studied and put into practical use. This embodiment is also a kind of such a production system. The present embodiment is a function for automatically adjusting the welding length when the work is displaced in the welding direction or when the length of the work in the welding direction varies and the work shapes vary. Is to have. Also, if the work installation error or work shape variation exceeds the permissible value for the product, it is automatically detected and notified to an external device, and the processing operation at the time of abnormality is automatically performed. It also has the function of performing.

In FIG. 2, which is an explanatory view of the operation program taught to the robot according to the embodiment of the present invention, the teaching position P2 is recorded at the longest position allowed when the welding length is long. The length 1 is the shortest length allowed when the welding length is conversely short, and is recorded as a command in the operation program. The teaching position P4 is a position to be headed in the event of an abnormality, and a plurality of teaching positions can be recorded after P4.

The operation of the robot for various weld lengths is shown in FIGS. FIG. 4 shows the operation of the robot when the welding length is within the allowable range, and the robot 1 moves toward the teaching position P3 which is the operation path in the normal state. FIG. 5 shows the operation when the welding length L is shorter than the allowable range. After the robot outputs an abnormal output signal, the robot moves to the teaching position P4 which is the operation path at the time of abnormality. FIG. 6 shows the operation when the welding length L is longer than the allowable range. After the robot outputs an abnormality signal, the robot moves to the teaching position P4 which is the operation path at the time of abnormality.

Next, the operation of the robot will be described.
FIG. 3 shows a flowchart of the processing contents performed by the microcomputer 9 in the robot control device 5, whereby the robot operation is controlled. In block 11, the robot 1 starts operation and teaches position P1.
The welding torch 2 heads toward the joint of the workpiece 4 while welding, and when the joint shape is detected in the block 11, the process proceeds to block 15, where it is checked whether the teaching position P2 is reached. If NO, the process returns to block 11 to continue detecting the joint shape, and if YES, the work 4
Means that it is longer than the distance between the teaching positions P1 and P2, and therefore it is out of the standard, so the process proceeds to block 16, where an abnormal output signal is output, then at block 17, the teaching position P4 is reached, and at block 18. End the program operation. If the joint shape is not detected in block 11, the process proceeds to block 12, the welded distance L from the taught position P1 to the current position is detected, and the process proceeds to block 13. Therefore, it is checked whether or not the distance L is larger than 1 defined as the shortest weldable length of the work 4, and if the result is NO, it means that the length of the work 4 is shorter than the allowable length. The same process as described above is performed. If YES, the process proceeds to block 14, where the welding torch 2 of the robot 1 is advanced toward the teaching position P3, and the program operation is ended at block 18.

[0016]

As described above, according to the present invention,
By setting the range in which normal work is performed according to the standard range of the product, it is possible to automatically detect the non-standard product, so that the non-standard product may be mixed in the subsequent process. In addition to enabling high quality control, even when workpieces of different types with different shapes are installed by mistake, it is possible to detect it and automatically execute processing at the time of abnormality. Therefore, it is possible to avoid a risk that the robot or the end effector interferes with and destroys the work or the jig, so that it is possible to configure the production equipment having high productivity. I was able to get it.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an arc welding system that realizes an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an operation program taught to a robot according to an embodiment of the present invention.

FIG. 3 is a processing flowchart of a microcomputer for realizing the embodiment of FIG.

FIG. 4 is an explanatory diagram of a robot operation within an allowable range according to the embodiment of FIG.

FIG. 5 is an explanatory diagram of a robot operation when the welding length is shorter than the allowable range according to the embodiment of FIG.

FIG. 6 is an explanatory diagram of the robot operation when the welding length is longer than the allowable range according to the embodiment of FIG.

FIG. 7 is an explanatory diagram of a teaching locus of a conventional robot.

FIG. 8 is an operation program diagram of a conventional robot.

FIG. 9 is an explanatory diagram of a conventional robot control method.

[Explanation of symbols]

 1: Robot 2: Welding torch 3: Sensor head 4, 41: Work 5: Robot controller 6: Sensor controller 7: Central controller 8: Other robot controller 9: Microcomputer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G05B 19/403 U 9064-3H

Claims (1)

Claim: What is claimed is: 1. A robot control method for reproducing a program based on a pre-teached work program, wherein an operation path of an end effector attached to the tip of the wrist of the robot is taught from a teach position P1 to a teach position. When programming to P2 and moving the end effector from the teaching position P1 to P2, when detecting the generation of a signal specifying that work has been performed from a sensor attached to the end effector or a peripheral device of the robot, If the position is more than a preset distance from the teaching position P1 and has not reached the teaching position P2, the teaching position P
After performing the operation to be performed in step 2, the teaching position P3 is moved to the next teaching position P3, and in other cases, a preset abnormal output signal is output and then the teaching position P4 is preset. Robot control system.