JP3065386B2 - Industrial robot control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial application] When the shape of the workpiece assembled by the industrial robot is uneven or the positioning of the workpiece has an error, the work can be performed by automatically changing the reproduction operation of the robot. And a method for controlling an industrial robot.

[0002]

2. Description of the Related Art Conventionally, as a control method for an industrial robot of this type, there has been a control method as shown in FIG. 9 (JP-A-57-113116, JP-A-57-113115). ). In summary, a detector is mounted near the movable part of the robot or near the motion path of the robot, a detection signal from the detector is detected, and the moving operation is stopped immediately or after moving for a predetermined distance. A robot control method is characterized in that a task to be performed is performed at a target position where the user is heading, and then the robot hand is moved to the next target position.

Further, the above prior art is disclosed in Japanese Patent Application Laid-Open No. 57-113.
More specifically, referring to FIG. 9 disclosed in Japanese Patent Publication No. 116-116, a robot control method in which a robot operation is taught in advance and a robot operation according to the teaching is performed according to the teaching data is performed. Contains 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 moves the robot hand from the current position P ₁ to the first target position. 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 defines the robot operation is generated, such as when the detected detector touches a target work, it is detected and the movement operation of the robot hand is immediately performed. 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 a robot control system adapted to move to the second target position P _3.

[0004]

However, in the above-mentioned prior art, there are cases where a product that is out of standard or a different kind of work having a different shape is mixed, or the shape of the work itself or the positioning of the work. In the case where there is a variation, there has not yet been developed any means capable of correctly determining and processing them.
Therefore, in the above-mentioned conventional technology, a nonstandard product proceeds to a later process and is mixed with a passing product, or an erroneous work is performed in the process for a different type of workpiece having a different shape, There has been a problem that it is not possible to correctly cope with an unspecified situation such as rejecting the work regardless of the mere variation in the shape or positioning of the work.

[0005] Therefore, an object of the present invention is to provide a method for manufacturing a product in which variations in the shape of the work itself, the positioning of the work, and the like, are caused.
If it is within the allowable range, the work position should be automatically changed in accordance with those variations, or if the variation is outside the allowable range, it should be notified to external peripheral devices and workers and performed there. By automatically performing the work, the out-of-specification product may go to the later process and be mixed with the passing product, or the wrong work may be performed in the process for different types of workpieces with different shapes. It is an object of the present invention to provide a control method for an industrial robot that prevents an accident and causes a work to be performed correctly even when there is some variation in the shape and positioning of a work.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a robot control method for reproducing a program based on a work program taught in advance, comprising an end effector attached to a tip end of a wrist of the robot. Is programmed so as to go from the teaching position P1 to the teaching position P2, and that while the end effector is moving from the teaching position P1 to the teaching position P2, the work is executed from the end effector or a sensor attached to a peripheral device of the robot. When the generation of the specified signal is detected, if the position is more than a preset distance from the teaching position P1 and does not reach the teaching position P2, the teaching position P
After performing the operation to be performed in Step 2, the robot moves to the next teaching position P3, and the position is set in advance from the teaching position P1.
Within the specified distance and has reached the teaching position P2.
If not, or the position is pre-set from the teaching position P1.
Distance greater than the set distance and
If reached, after outputting the error output signal set in advance, it has solved the above problems by providing a method of controlling an industrial robot, characterized in that as toward the teaching position P4 previously set .

[0007]

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

In FIG. 1, a robot 1 has a welding torch 2 as an end effector attached to a tip end of a wrist, and a sensor head 3 for detecting a joint shape of a work 4 is attached to the welding torch 2. 6 is a sensor head 3
And a signal indicating whether or not the joint shape of the workpiece 4 has been detected.
Send to The robot controller 5 transmits a signal indicating the state of the robot to the central controller 7. The central control device 7 controls a plurality of robot control devices. For example, when an abnormality occurs in a certain robot, a lamp is turned on to determine which type of abnormality has occurred in which robot. It informs the operator and outputs an abnormal signal to a higher-level control device.

The teaching operation of the robot will be described with reference to the example of the explanatory diagram of the teaching locus of the conventional robot in FIG. 7. A series of straight lines with arrows represent the teaching locus for the work 42.
Note that the robot 1 employs an operation according to a teaching playback method. Further, since the robot control device 5 has a linear interpolation function, a teaching point is unnecessary in a portion operated in a straight line, and a point for changing the operation direction (here,
It is only necessary to teach only P0, P1, P2, and P3).
For example, when the robot performs an arc welding operation, the programmable general-purpose output signal of the robot controller 5 is connected to an input circuit for generating an arc of the arc welding machine, and the robot is connected to the robot. Apply a general-purpose output signal to the point where you want to start arc welding in the operation program.
The command to turn off the general-purpose output signal may be recorded at a place where the arc welding is to be ended, in advance, by recording the command to perform N. In the example of FIG. 7, a command to turn on the general-purpose output signal is recorded at the teaching position P1, and a command to turn 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 operations, and can be reproduced during automatic operation. FIG. 8 shows an operation program of such a robot.

[0010] Industrial robots are often used in the field of working on a few types of works of the same type. In this case, all of a plurality of works having the same work shape and a relative positional relationship between the robot and the work are used. It is a prerequisite that they are the same. This is because the teaching playback type robot repeats the operation as taught.

However, depending on the type of the work, there is a case where the accuracy of the shape of the work is not so required, and the accuracy of the jig for fixing the work is sometimes not good. It can be difficult. Even in such a case, for the purpose of automation, the precision of the workpiece shape is both set higher than the precision required by the product,
Also, making a high-precision jig is not preferable because it leads to an increase in the cost of the product itself and the cost of production equipment.

In such a background, a robot and a sensor have recently been combined to provide an adaptive function such as correcting the reproduction position on the robot side even when the accuracy of the workpiece shape or the accuracy of the jig is not good. Production systems have been studied and put to practical use. This embodiment is also a kind of such a production system. This embodiment has a function of automatically adjusting the welding length in a case where the workpiece is displaced in the welding direction, or in a case where the length of the welding direction varies in the shape of the workpiece and there is a variation. It has. If the work placement error or work shape variation exceeds the allowable value for the product, it is automatically detected and notified to an external device, and the processing action at the time of abnormality is automatically performed. It also has a function to perform.

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

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

Next, the operation of the robot will be described.
FIG. 3 shows a flowchart of the processing performed by the microcomputer 9 in the robot control device 5, whereby the robot operation is controlled. In block 11, the robot 1 starts operating, and the teaching position P1
The welding torch 2 moves toward the joint of the work 4 while welding, and if the joint shape is detected in the block 11, the process proceeds to block 15, where it is checked whether or not the teaching position P2 has been reached. If NO, the process returns to block 11 to continue the detection of the joint shape.
Means that the distance is longer than the distance between the teaching positions P1 and P2. Therefore, the process proceeds to block 16 because it is out of the standard. After outputting an abnormal output signal there, the process proceeds to the teaching position P4 in block 17, and the process proceeds to block 18. End the program operation. If the joint shape is not detected in the block 11, the process proceeds to the block 12, where the welding distance L from the teaching position P1 to the current position is detected, and the process proceeds to the block 13. Then, it is checked whether or not the distance L is larger than 1 which is set as the shortest length of the work 4 that can be welded. If NO, it means that the length of the work 4 is shorter than the allowable length. The same processing as described above is performed, and in the case of YES, the process proceeds to block 14, where the welding torch 2 of the robot 1 is advanced to the teaching position P3, and the program operation ends in block 18.

[0016]

As described above, according to the present invention,
By setting the range of normal work according to the specification range of the product, it is possible to automatically detect non-standard products, so that non-standard products will be mixed in subsequent processes beforehand. High quality control is possible, and even if different types of workpieces with different shapes are installed by mistake, it can be detected and the processing at the time of abnormality can be automatically executed. Therefore, it is possible to avoid a danger that the robot or the end effector interferes with and breaks a workpiece or a jig, thereby providing a remarkable effect that a production facility having high productivity can be configured. I got it.

[Brief description of the 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. 2;

FIG. 4 is an explanatory diagram of a robot operation within an allowable range according to the embodiment of FIG. 2;

FIG. 5 is an explanatory diagram of a robot operation when the welding length according to the embodiment of FIG. 2 is shorter than an allowable range.

FIG. 6 is an explanatory diagram of a robot operation when the welding length according to the embodiment of FIG. 2 is longer than an allowable range.

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 (58) Field surveyed (Int.Cl. ⁷ , DB name) G05B 19/42 B23K 9/095 G05B 19/18

Claims (1)

(57) [Claims] 1. A robot control method for reproducing a program based on a work program taught in advance, wherein an operation path of an end effector attached to a tip end of a wrist of the robot is programmed to go from a teaching position P1 to a teaching position P2. While the end effector is moving from the teaching position P1 to the teaching position P2, when the generation of a signal specifying that the work has been performed from a sensor attached to the peripheral device of the end effector or the robot is detected, the position is determined to be the teaching position. If the distance from P1 is greater than or equal to a preset distance and does not reach the teaching position P2, the teaching position P
After performing the operation to be performed in Step 2, the robot moves to the next teaching position P3, and the position is set in advance from the teaching position P1.
Within the specified distance and has reached the teaching position P2.
If not, or the position is pre-set from the teaching position P1.
Distance greater than the set distance and
A method for controlling an industrial robot, comprising: outputting a preset abnormal output signal when reaching, and then heading to a preset teaching position P4.