JPH07104133B2 - Work position detector - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work position detecting device using an image sensor, and more particularly to a work position detecting device capable of maintaining good reproducibility of attachment of an image sensor.

“Prior Art” As a work position detecting device using an image sensor, as shown in FIG. 9, an image sensor I is arranged on a side of a conveyance line L of a work W, and the image sensor I is sandwiched across the line L. The light source K is arranged at a position facing the workpiece W, and the light source K is projected from the light and dark of a part of the image of the workpiece W projected on the image sensor I.
There is a thing to figure out the position of.

In such an apparatus, the image sensor I may be replaced or readjusted from time to time. In that case, in the conventional case, the work W is stopped at a fixed position and the stopped work W is used as a reference. I'm adjusting.

[Problems to be Solved by the Invention] In order to perform the above-described adjustment accurately, it is a condition that the work W is accurately fixed at the reference position. However, when the work W is supported by an unstable device such as a conveyor, it is difficult to accurately stop the work W at the reference position. Therefore, there is a problem that the reproducibility of mounting the image sensor cannot be kept good as a result.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a work position detecting device which can solve the above problems and keep good reproducibility of attachment of an image sensor.

"Means for Solving Problems" The present invention has the following configuration in order to achieve the above object. That is, an apparatus having a light source and an image sensor having a finder for receiving an image of a work located between the light source and detecting the position of the work and projecting the image, the image sensor and the light source In between, a reference positioning jig for projecting an image at a predetermined position of the finder of the image sensor in a proper state for detecting the position of the work is always provided.

[Operation] By adjusting the image sensor so that the reference positioning jig projects an image at the predetermined position of the finder of the image sensor, the image sensor is in an appropriate state for detecting the position of the work. Therefore, it is not necessary to use the work as a reference.

[Examples] Examples of the present invention will be described below with reference to FIGS. 1 to 8.

First, regarding the device for detecting the one-dimensional position of the work,
Describing with reference to FIG. 4 to FIG. 4, an alignment plate (reference positioning jig) 20 is fixedly provided immediately before the image sensor I. The edge 20a of this alignment plate 20
The image is vertically set so as to be within the field of view F of the image sensor I which is just arranged.

FIG. 2 is an image shown in the visual field F of the image sensor I. In order to adjust the image sensor I, first, the measuring portion S (center line) in which the image of the light source K is engraved in the finder
The image sensor I is adjusted so that the inside of the finder is visually observed as shown above, and then the data of the edge portion 20a of the alignment plate 20 is exactly at the reference position. This ensures the reproducibility of mounting the image sensor I. Note that W indicates a front pillar of the vehicle body as a work.

FIG. 3 shows a modification of the alignment plate 20 of this embodiment. In this modification, a square window is formed in the center of the alignment plate 21.
22 is opened, and its window 22 is set to be located immediately in front of the image sensor I. The window 22 is set so that the image of the edge portion 22a of the window 22 and the edge of the field of view F of the finder overlap each other when viewed by the viewfinder of the image sensor I properly arranged. When adjusting with this device, while looking at the viewfinder of the image sensor I,
As shown in FIG. 4, the image sensor I may be adjusted so that the edge of the field of view F of the finder coincides with the image of the edge 22a of the window 22 of the alignment plate 21.

As described above, according to the apparatus of this embodiment, even if the position of the image sensor I is slightly displaced for some reason, the readjustment can be performed quickly. Further, the adjustment is possible even when the work W is between the image sensor I and the light source K.

Next, an example of a system for detecting the three-dimensional position of a work to which the present invention is applied will be described with reference to FIGS. This system is a vehicle body position shift detection system for a painting robot in an automobile manufacturing line. Reference numbers 1 to 3
Is a one-dimensional image sensor, and each of these image sensors 1 to 3 is provided on one side of a line to which a vehicle body (work) 4 is intermittently sent.
A light source 5 composed of a high-frequency lighting fluorescent lamp is provided at a position facing the image sensor 1 across the line, and by detecting a light beam emitted from the light source 5, the front pillar 4a of the vehicle body 4 is detected. The position in the line advancing direction (hereinafter referred to as the X-axis direction) is measured.

A light source 6 configured similarly to the light source 5 is provided at a position facing the image sensor 2, and by detecting a light beam emitted from the light source 6, the lower end portion of the front wheel house 4b is detected. The position in the vertical direction (hereinafter referred to as the Z-axis direction) is measured.

A light source 7 having the same structure as the light sources 5 and 6 is provided at a position facing the image sensor 3, and a rear wheel of the vehicle body 4 is detected by detecting a light beam emitted from the light source 7. The vertical position of the lower end of the house 4c is measured.

Further, reference numerals 8 and 9 each denote an ultrasonic distance sensor as a one-dimensional sensor.
9 is designed to measure the distance from the vehicle body 4 at two locations apart from each other in the front-back direction of the vehicle body 4.

Further, an ultrasonic distance sensor 10 for correction is provided at a position rearward of the ultrasonic distance sensors 8 and 9, and the ultrasonic distance sensor 10 constantly measures a known distance L so that the temperature Alternatively, a correction signal is obtained to correct the measurement error of the ultrasonic distance sensors 8 and 9 due to the change in atmospheric pressure.

The image sensors 1 to 3 are connected to the arithmetic unit 17 via the converters 11 to 13, and the ultrasonic distance sensors 8 to 10 are connected to the arithmetic unit 17 via the converters 14 to 16, respectively.
Further, a storage device 18 is connected to the arithmetic unit 17.

The operation of the detection device having such a configuration will be described by taking the one-dimensional image sensor 1 as an example. The image sensor 1 detects a bright and dark pattern as shown in FIG. Then, n elements constituting the image sensor 1 (in the figure, the length in the X-axis direction is indicated by the number)
The position of the pillar 4a is detected depending on which position of the element is OFF (dark) at the position of the distance i in the illustrated example, and from this, the arithmetic unit 17 recognizes the position of the vehicle body in the x-axis direction. . In the image sensors 2 and 3, the position of the vehicle body 4 in the z-axis direction is detected by the same principle, and further, the rotational position around the y axis is detected from the measured values of the image sensors 2 and 3. It is like this.

On the other hand, the transducers 14 and 15 measure the times T ₁ and T ₂ required for the ultrasonic waves transmitted from the ultrasonic distance sensors 8 and 9 to be reflected by the vehicle body 4 and received. From each sensor to the vehicle body 4 by processing
The axial distances L ₁ and L ₂ are obtained, and the rotational position around the z axis is obtained.

L ₁ = L × T ₁ / TL ₂ = L × T ₂ / T where L ₁ is the distance between the ultrasonic distance sensor 8 and the vehicle body L ₂ is the distance between the ultrasonic distance sensor 9 and the vehicle body 4 Five pieces of one-dimensional distance information are obtained from the image sensors 1, 2, 3 and the ultrasonic distance sensors 8.9, and the arithmetic unit 17 stores these one-dimensional distance information in the storage device 18 as sensor detection values. The vehicle body displacement amount is calculated by performing processing according to the relational expression of “the vehicle body position displacement is good”.

The present invention can be applied to the above system, but can of course be applied to a work position detecting device using other image sensors.

"Effect of the Invention" According to the present invention, an apparatus having a light source and an image sensor having a finder that receives an image of a work located between the light source, detects the position of the work, and projects the image. In the meantime, between the image sensor and the light source, since a reference positioning jig for projecting an image at a predetermined position of the finder of the image sensor in a proper state for detecting the position of the work is always provided, the image sensor is replaced, When adjusting, adjust the image sensor so that the reference positioning jig projects an image at the default position of the finder of the image sensor, and the image sensor will be in the proper state to detect the position of the work. Can be obtained.

Therefore, it is possible to improve the adjustment efficiency and operate the industrial robot by using the past sensing data before the image sensor replacement.

[Brief description of drawings]

1 to 4 show an embodiment of an apparatus for detecting a one-dimensional position of a work according to the present invention. FIG. 1 is a perspective view, and FIG. 2 is shown in a viewfinder field of view when adjusting an image sensor. FIG. 3 shows an image, FIG. 3 is a plan view showing a modified example of the alignment plate, and FIG. 4 is a view showing an image in the viewfinder field when adjusting the image sensor when the alignment plate is used.
5 to 8 are views for explaining an embodiment of a system for detecting a three-dimensional position of a work to which the present invention is applied, and FIG. 5 is a plan view showing the configuration of the system, and FIG.
FIG. 7 is a side view, FIG. 7 is a front view, FIG. 8 is an explanatory view of a measurement principle of one one-dimensional image sensor, and FIG. 9 is for explaining a conventional technique of a work position detecting device which is a problem here. It is a perspective view shown in FIG. I ... Image sensor, W ... Work, K ... Light source, 1,
2,3 ... 1-dimensional image sensor, 4 ... Car body (work), 5, 6, 7 ... Light source, 20, 21 ... Positioning plate (reference positioning jig).

Front Page Continuation (72) Inventor Shinji Kumagai 4107 Akuwa-cho, Seya-ku, Yokohama-shi, Kanagawa Tokiko Mitsukyo Dormitory

Claims (1)

[Claims] 1. An apparatus comprising: a light source; and an image sensor having a finder for receiving an image of a work located between the light source and detecting the position of the work and projecting the image. A work position detecting device, characterized in that a reference positioning jig for projecting an image at a predetermined position of the finder of an image sensor in an appropriate state for detecting the position of the work is always provided between the sensor and the light source.