JPH05228861A - Control method of industrial robot - Google Patents

Abstract

PURPOSE:To improve the extent of productive efficiency by detecting and storing an operating position if a work being fed is the first one, and performing the work at this operating position, while if the work is after the second one, performing the work after moving a robot to the stored operating position. CONSTITUTION:A robot 10 consists of a head part 11 equipped with a work tool 12 and a visual sensor 13, a robot body 14 moving this head part 11, a controller 15 connected to this robot body 14 via a cable 20, and a counter 16, etc., connected to the controller 15 via the cable 20. In addition, a screw 32 is screwed in a hole 33 of a work 31 being transferred through a belt conveyor 21, by the robot 10. In this case, whether this work 31 is the first one or not is judged, and if it is the first one, an operating position is detected and stored by the visual sensor 13, while work is carried out at this operating position. On the other hand, if the work 31 is after the second one, the work is carried out after moving the head part 11 to the operating position stored in memory.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling an industrial robot. For convenience of explanation, the industrial robot will be described as a screw tightening robot.

[0002]

2. Description of the Related Art In such a screw tightening robot, a work tool such as an electric screwdriver provided on a head portion is moved to a predetermined work position on a work, and the movement position data of the work tool is fed back to a controller. The screw tightening work is performed by controlling the movement of the work tool, that is, the head portion so that the movement position data of the work tool matches the predetermined work position data. However, in this method, in the case of a plastic molded product or a work of a sheet metal processed product having a large external dimension, in which the molding size is easily influenced by external factors such as molding conditions and temperature, it is necessary to specify a predetermined work position for each work. It was

In order to solve the above problems, a visual sensor is attached to the head portion, and after moving to a prescribed working position instructed, the visual sensor detects an actual working position such as a screw pilot hole, Obtaining an actual work position to which the work tool should move, that is, a corrected work position, from the detected work position data, the indicated work position data, the attachment position relationship data between the work tool and the visual sensor, and moving the work tool to the corrected work position. Are performing screw tightening work.

[0004]

However, when the work position is corrected by using the visual sensor for each work position on the work, the sum of the time for calculating the correction work position and the movement time for the correction, that is, Since the correction time is added to the working time, there is a drawback that the production efficiency does not increase. It is an object of the present invention to provide a method for controlling an industrial robot, which can eliminate the above-mentioned drawbacks of the prior art and improve the production efficiency of the industrial robot.

[0005]

In order to achieve the above object, in the control method of the present invention, in the case of a work made of the above-mentioned plastic molded product or sheet metal processed product, the molding size in the same lot is substantially constant. In consideration of the fact that the correction work position on the first work of the lot is determined and stored using a visual sensor, the head is moved according to the stored correction work position data from the next work until the lot changes. It is something that is done.

[0006]

According to the control method described above, the time required for calculating and determining the corrected work position of the second and subsequent works and the movement time for correction, that is, the correction time can be omitted, so that the production efficiency can be improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows the overall construction of a screw tightening robot apparatus. The robot 10 includes a head portion 11 to which a work tool 12 including an electric screwdriver and a visual sensor 13 including, for example, a television camera are attached, and the head portion 1.
Robot body 1 for moving 1 through two arms
4, a controller 15 connected to the robot body 14 via a cable 20, a counter 16 connected to the controller 15 via a cable 20, and the like. Work 3 transferred by belt conveyor 21
1 has four screw pilot holes 33 into which screws 32 are screwed, and the screw 32 is temporarily stopped at the work station in which the head portion 11 is located, and the screw 32 is screwed into the screw pilot holes 33 by the work tool 12. After the screw 32 is screwed in, it is sent out from the work station and the next new work piece 3
1 is sent to the work station, and the screw tightening work is performed thereafter as described above. The controller 15 controls to move the head portion 11 to the work position on the work 31 via the robot body 14 and to move the work tool 12 to the corrected work position of the screw hole 33 using the output of the visual sensor 13. To do. The counter 16 is provided to determine whether the work 31 is the first lot.

FIG. 1 is a block diagram showing the internal configuration of the controller 15, the relationship between the controller 15, the visual sensor 13 and the counter 16. The visual recognition device 51 for image-processing the image data from the visual sensor 13 to detect the position of the screw hole 33 detects the detected positional data as C
Send to PU52. The CPU 52 calculates the corrected work position data from the predetermined work position data from the positioning control device 53, the detected position data from the visual recognition device 51, and the attachment position relationship data of the work tool 12 and the visual sensor 13, and the corrected work position data. RA for each of the 4 screw holes
Store in M54. The two positioning control devices 53 are provided to indicate the positions of the two arms.

FIG. 4 is a plan view showing the work station section. The work 31a is the last work of the lot A that has not been deformed during molding, the work 31b is the first work of the lot B, and the work 31C is the second work of the lot B. Work.
The work 31b and the work 31C are examples of being deformed by heat, for example. The work 31 sent to the work station by the belt conveyor 21 is fixed to the work fixing jig 22,
In this state, the screw 32 is screwed in. Reference numeral 23 is a stopper for preventing the next work 31 from being sent to the work station.

FIG. 5 shows a predetermined working position 33 of the screw pilot hole 33 indicated by a solid line instructed by the positioning control device 53.
a and the screw pilot hole 3 on the work 31 of the lot B that has been thermally deformed
3 shows the correction work position 33b. When the first work 31b of the lot B is fed, as described above, the visual sensor 13, the CPU 52, etc. calculate the respective positions of the correction work position 33b to which the work tool 13 should move, and store them in the RAM 54. After 31c, the head unit 11 is moved according to the data stored in the RAM 54.

The control method of the present invention will be described with reference to the flowchart of FIG. The counter 16 has a counter 1 when the screw tightening work of the last work 31a of the lot A is completed.
It is assumed that the number of works 31 for each lot is preset so that the count value of 6 becomes 0. The work 31b carried in from the belt conveyor 21 is fixed by the work fixing jig 22 (step S1 and subsequent steps will be simply referred to as S1).
The CPU 52 determines whether or not it is the first work 31b of the lot B based on the count value of the counter 16, and if it is 0, determines that it is the first work 31b of the lot B, and if it is not 0, it is the second or subsequent work 31 (S2). ). Here, since it is 0, that is, the first work 31b of the lot B, the visual sensor 13 is positioned above the first screw pilot hole 33 at the predetermined work position data P1, and the work tool 12 is calculated after calculating the positional deviation of the screw pilot hole 33. Is positioned directly above the screw pilot hole 33 (S3). It is assumed that the correction time of the visual correction positioning (S3) of the first screw pilot hole 33 requires k seconds. Next, the corrected position data P1 ′ of the first screw pilot hole 33 is stored and updated in the RAM 54 in association with the predetermined work position data P1 (S4), and the screw tightening work (S5) is performed by the work tool 12. In the case of the second screw pilot hole 33, the same processing as that of the first screw pilot hole 33 is performed, and the same correction time k seconds as that of the first screw pilot hole 33 is required. When visual correction is performed for each predetermined work position on the work 31, the work 31 of the lot B shown in FIG. 5 has only the fourth screw pilot hole 33, but if there is the nth screw pilot hole 33, the nth screw pilot hole 33 is provided. When the visual correction positioning of the th screw pilot hole 31n is completed, a total correction time of k × n seconds is required. This completes the screw tightening work for the first work 31b of the lot B, and the RAM 54 has the item number 1 shown in FIG.
The corrected position data P1 'to Pn' of ~ n are stored. Next, the counter 16 receives the reset signal output from the CPU 3, and presets the number m of works in the lot B (S6). The first work 31b of the lot B is conveyed by the belt conveyor 14, the counter 16 is decremented (S7), and the screw tightening target work 31c is loaded and fixed again (S1).
Next, it is determined whether the loaded work 31c is the first work of the lot B (S2), and since it is the second and subsequent works of the same lot, the process of (S8) is performed. Since the forming dimension of the work 31 in the same lot is stable, the stored correction position data P1 ′ is extracted from the predetermined work position data P1 of the first screw pilot hole 33 and the correction position data P1 ′ is obtained in (S8). The working tool 12 is positioned directly above the screw pilot hole 33 by. At this time, since visual correction is not performed, no extra time is required. Next, the screw tightening work is performed, and the second screw pilot hole 33 to the nth screw pilot hole 3
Position with the corrected position data stored up to 3 and execute the screw tightening work.

These series of operations are repeated, and at the end of the screw tightening operation of the works 31 of the number m of works of the lot B, compared with the conventional method in which the individual screw pilot holes 33 are visually corrected for each predetermined work position. The total assembly work time is (m-1) × k × n (seconds) and the production efficiency can be improved.

[0013]

As described above, according to the present invention, the actual work position of the first work in the lot is visually corrected and stored, and the second and subsequent works move the work tool according to the stored corrected work position data. Since the positioning is performed, the production efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of a controller used in a control method of the present invention.

FIG. 2 is a flowchart showing a control method of the present invention.

FIG. 3 is a perspective view showing an overall configuration of a screw tightening robot device.

FIG. 4 is a plan view showing a work station unit of FIG.

FIG. 5 is a plan view showing a relationship between a predetermined work position on a work and a correction work position.

FIG. 6 is an explanatory table showing an example of data stored in RAM.

[Explanation of symbols]

10 is a screw tightening robot, 11 is a head part, 12 is a work tool, 13 is a visual sensor, 14 is a robot body, 15
Is a controller, 16 is a counter, 31 is a work, 33
Is a screw hole, 51 is a visual recognition device, 52 is a CPU, 53
Is a positioning control device, and 54 is a RAM.

Claims (1)

[Claims] 1. A work tool, comprising a head having a work tool and a visual sensor, and a work feeding device for feeding a work having at least one work position to a work station, wherein the head is moved to a work position on the work. In the industrial robot that performs the work by sending the work by the work feeding device after the work is finished and sends the next work to the work station, it is determined whether the work is the first work of the lot. For the first work, the work position on the work is detected and stored by the visual sensor, and the work is performed at the work position. When the work is the second work or later, the head is moved to the stored work position to perform the work. A method for controlling an industrial robot, characterized in that