JPH06210580A - Workpiece gripping compensating device - Google Patents

Abstract

PURPOSE:To prevent a workpiece or a gripping device from being damaged during gripping of the workpiece by providing a compensating means for comparing a position of the workpiece which is recognized from a measured distance to the workpiece, with a standard position so as to compensate a deviation therebetween. CONSTITUTION:When a workpiece 20 gripped by a hand 10 of an industrial robot 11, is shifted, the hand 10 is at first moved to a scan starting position where the workpiece 20 is set, and the hand 10 is then moved for scanning in order to measure a distance to the workpiece 20. Simultaneously, the distance is measured by a distance measuring sensor 11, and a left side edge is detected in accordance with a variation in the measured distance. At this time, the position in the scanning direction (x-axis) is written on a table. Then, a height of the workpiece 20 and a left edge are detected in the mentioned order, and whether compensation is required or not is determined in accordance with detected data. If it is required, the compensation is made from a gripping position where the position of the hand 10 has been previously taught so as to move the hand 10 to the gripping position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work grip correction device for accurately gripping a work when gripping the work using an industrial robot or the like.

[0002]

2. Description of the Related Art A conventional gripping device for gripping a work by using an industrial robot or the like recognizes the position up to the work and the state of the work when gripping the work by a teaching operation to the gripping device which is performed in advance. The work is gripped by the gripping device playing back the work position thus set.

However, in such a playback type gripping device, when the position of the work is deviated, the position of the work deviates from the position taught by the gripping device. As shown, there is a problem in that the hand 10 of the gripping device collides with the work 20 and damages the hand 10 or the work 20.

[0004]

Therefore, the present invention corrects the gripping position so that the work can be accurately gripped without collision between the work and the hand even when the work is displaced from a predetermined position. The present invention is to provide a work grip correction device.

[0005]

SUMMARY OF THE INVENTION The above-mentioned objects are to provide a distance measuring means for measuring a distance to a work, a work position recognizing means for recognizing a work position from the distance measured by the distance measuring means, and the position recognition. This is achieved by a work gripping correction device having a correction unit that compares the position obtained by the means with standard position data given in advance and corrects the deviation.

[0006]

The present invention recognizes the distance and height from the gripping device to the work by the distance measuring means for measuring the distance to the work, calculates the deviation from the work position taught in advance, and calculates the deviation. Is corrected and the gripping position is corrected from the taught gripping position, so that the work can be gripped accurately.

Further, in the present invention, the distance measuring means for measuring the distance to the work is provided in the gripping device itself, so that when the gripping device performs the gripping operation, the work is scanned from one end to the other end to measure the distance. Therefore, a device for scanning a work for performing distance measurement separately from the gripping operation is unnecessary.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram for explaining a gripping device using the work gripping correction device of the present invention. This gripping device is a robot 11 or a robot 1 which is a gripping device.
1. The distance measuring sensor 1 provided on the hand 10 of FIG. 1, the edge detecting unit 2 for detecting the edge of the work 20 by the distance measuring data from the distance measuring sensor 1, the position and height of the work from the edge detection signal and the distance measuring data. The correction processing unit 3 recognizes and corrects the position of the hand 10 of the robot.

The distance measuring sensor 1 is attached to a hand 10 of a robot, for example, a system of irradiating a laser beam and reading a spot light formed by irradiating the radiated light with an object by a CCD sensor, ultrasonic waves or radio waves. Is a distance measuring device that utilizes the reflection of the work, and is for measuring the distance to the work by scanning the work by moving the hand 10.

The edge detection section 2 is for recognizing the position of the edge portion of the work from the distance measurement result of the distance measurement sensor 1. For example, the hand 10 scans the work 20 while the hand 10 moves laterally. As a result, when distance measurement data as shown in FIG. 2 is obtained, the point on which the distance measurement data changes most is taken as the edge, and the scanning direction at that time is taken as the x axis. When the change point is shown, the left edge position x (i) is set, and the last change point is set as the right edge position x (j). In FIG. 2, the horizontal axis is the scanning direction, and the vertical axis is the height h direction when the surface on which the work 20 is placed determined from the distance measurement data has a height of 0.

In the correction processing unit 3, first, the edge detection unit 2
From the edge position data from and the height h (i) obtained from the data from the distance measuring sensor, the left edge position, the height, and the right edge position as shown in FIG. Create a separate table. Here, the shift amount is the left side edge Ls taught to the robot 11 in advance from the values of the measurement data x (i), h (i) and x (j),
It is a value obtained by subtracting the work height Hs and the right edge Rs, and the judgment is NG when it is judged that correction is necessary when the size of the deviation is larger than a certain value determined by the hand opening width. If no correction is required, it is OK. When the determination is NG, the gripping position is corrected from the standard position taught in advance for gripping the work, and the hand is moved.

Next, the operation of the gripping device using this work gripping correction device will be described. FIG. 4 is a flowchart for explaining the gripping operation. First, the hand 10 of the robot 11 is moved to the scan start position where the work 20 is placed (S1), and the hand is moved to measure the distance to the work 20 to start scanning (S1).
2). The distance is measured by the distance measuring sensor 1 at the same time as the scanning is started, and the left edge is detected by the change of the distance measuring distance (S3).
Write (i) to the table. At this time, if the scan end position is reached without detecting the left edge, that is, without changing the measurement distance, it is considered that there is no work and the gripping operation is ended. When the left edge is detected, the height h (i) of the work is measured with the distance at that time as 0 on the surface on which the work is placed (S4) and written in the table, and the work height is within the specified range. If it is determined to be within the range (S5), the right edge is detected, that is, the final change point of the distance measurement distance is detected (S6). At this time, it is determined that the height of the work is out of the specified range (S5),
If the right edge is not detected and the scanning end position is reached, the workpiece 20 ends the gripping operation because the robot hand 10 is not within the gripping operable position, and when the right edge is detected, the Scan direction (x
Write the x) position x (j) in the table. Next, referring to the table, when it is determined that the correction is necessary (S7), the position of the hand 10 is corrected from the gripping position that is taught in advance and the hand 10 is moved to the gripping position (S7).
8) The work is gripped (S9), and the gripping operation is completed.

In the above-described embodiment, the distance measuring sensor 1 is provided in the hand 10 of the robot which is a gripping device to scan the work, and the work is scanned by moving the hand 10. Although the scanning operation means used is unnecessary, in addition to this, as shown in FIG.
6, a polygon mirror or scanner 101 for moving the laser beam is provided, or a cylindrical lens 102 is provided as shown in FIG. 6, so that the laser from the laser light source 30 can be moved without moving the hand 10 itself. Scan the workpiece 20 by moving the light,
The position of the work may be measured by receiving the CD sensor 31.

[0015]

As described above, according to the workpiece gripping correction apparatus of the present invention, the lateral displacement and the height displacement of the workpiece from the standard position are measured, and the workpiece is gripped by correcting the displacement. In this case, it is possible to prevent the work or the gripping device from being damaged.

Further, by providing the distance measuring means in the gripping device, it becomes possible to perform the operation for distance measurement by the operation of the gripping device. For this reason, the operating means for distance measurement becomes unnecessary.

[Brief description of drawings]

FIG. 1 is a block diagram of a gripping device using a work gripping correction device of the present invention.

FIG. 2 is a view illustrating an edge and height measurement of a work according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a table of measurement results of edge and height measurement of a work according to an embodiment of the present invention.

FIG. 4 is a flowchart for explaining the operation of the gripping device using the work gripping correction device of the present invention.

FIG. 5 is a view for explaining an example of a distance measuring sensor used in the work grip correcting device of the present invention.

FIG. 6 is a view for explaining another example of the distance measuring sensor used in the work grip correcting device of the present invention.

FIG. 7 is a drawing showing a state of a gripping operation of a gripping device using the work grip correcting device of the present invention, FIG. A is a bird's eye view, and FIG. B is a front view of a hand portion.

FIG. 8 is a view showing a state of a gripping operation of a conventional work gripping device, FIG. A is a bird's eye view, and FIG. B is a front view of a hand portion.

[Explanation of symbols]

1 ... Distance measuring sensor, 2 ... Edge detection unit, 3 ... Correction processing unit,
10 ... Hand, 11 ... Robot,
20 ... work, 30 laser light source,
31 ... CCD sensor, 101 ... Polygon mirror or scanner, 102 ... Cylindrical lens.

Claims (2)

[Claims] 1. A distance measuring means for measuring a distance to a work, a work position recognizing means for recognizing a work position from a distance measured by the distance measuring means, and a position given by the position recognizing means in advance. A work gripping correction device having a correction unit that compares the standard position data stored therein and corrects the deviation. 2. The distance measuring means for measuring the distance to the work is provided in the gripping device.
The workpiece gripping correction device described in.