JPH11311503A - Photoelectric detector - Google Patents

Abstract

(57) [Problem] To provide a detection device that can detect a detection target using an inexpensive photoelectric sensor not only within a predetermined range but also at a position farther or closer than the predetermined range. . SOLUTION: The photoelectric detection device 1 is composed of two photoelectric sensors A and B whose detection distances are set to be different from each other, and the light emitting and light receiving portions of each photoelectric sensor are located on the same surface side. It is configured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric detecting device used for detecting the position of a work by a robot in an automated line for processing and assembling the work, for example.

[0002]

2. Description of the Related Art In a robot system for automatically transferring, processing, and assembling a work, an edge of the work is detected in a hand portion of a robot that holds the work, transfers the work to a transfer destination, and places the work. As a detection device for performing, for example, a photoelectric sensor having a light emitting unit and a light receiving unit is provided,
Thus, it is detected that the hand unit has come close to the position where the work can be held. "Transmissive" for photoelectric sensors,
There are a “reflection type” and a “limited reflection type”, and each of the detection outputs is in one of two states of ON or OFF.

A "reflection type" photoelectric sensor detects the presence of an object such as a workpiece by irradiating the object with light emitted from a light emitting section and receiving the reflected light at a light receiving section. As shown in FIG. 5, a photoelectric sensor S in which a light emitting unit E and a light receiving unit R are arranged at a predetermined interval on one surface of a substantially rectangular parallelepiped case, as shown in FIG. The sensor is turned ON only when the object W exists within a predetermined distance range (a hatched area) from a surface T (hereinafter, referred to as an “operation surface”) of the portion R, and is referred to as a “limited reflection type” sensor.

[0004]

However, since the above-mentioned "transmission type" and "reflection type" photoelectric sensors have only two states, that is, the output is ON or OFF, an object cannot be detected by the output alone. It cannot be determined that it exists at a position or range at a predetermined distance from. Further, in the “limited reflection type” photoelectric sensor, the detection point (object detection position) is only within the shaded region in FIG. 6 and is outside a predetermined distance from the photoelectric sensor, that is, a position farther or closer than the predetermined range. Whichever object is located, the object is not detected.
Therefore, in the robot system, there is a disadvantage that the work is not detected even if the hand unit is too close to the work.

In order to detect the distance to the object or the position of the object, it is conceivable to use a precise distance sensor or displacement meter using a laser. However, these are small enough to be mounted on the hand part of the robot. However, there is a problem that it is not manufactured and is expensive.

An object of the present invention is to provide a detection device that can detect a detection target using an inexpensive photoelectric sensor not only within a predetermined range but also at a position farther or closer than the predetermined range. That is.

[0007]

SUMMARY OF THE INVENTION The present invention comprises two photoelectric sensors whose detection distances are set to be different from each other, and the light emitting and light receiving portions of each photoelectric sensor are located on the same surface side. It is characterized by having done.

According to the present invention, on the surface (working surface) side where the light-emitting and light-receiving portions of each photoelectric sensor are located, the region where the object exists is the region where both photoelectric sensors do not detect,
It is divided into three areas: a region where only the farthest detection distance of the two photoelectric sensors detects, and a region where both photoelectric sensors detect both. Therefore, it can be determined whether the object is at a position farther from the apparatus, a predetermined (proper) position, or a close position, depending on whether one or both of the two photoelectric sensors detect.

In the photoelectric detection device of the present invention, it is preferable that the detection points of the two photoelectric sensors are located on the boundary between the two sensors. According to this configuration, there is no deviation (difference) between the detection points of the two photoelectric sensors in a direction (lateral direction) perpendicular to the boundary surface, and even when a small object or a thin object is detected, The detection device can detect accurately without malfunction.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a photoelectric detection device according to an embodiment of the present invention.
“Appropriate” or “near” is detected.

In FIG. 1, a photoelectric detecting device 1 comprises two photoelectric sensors (in this case, "reflective" sensors) A and B arranged adjacent to each other in parallel with each other, and the light emitting portions E ₁ and E ₁ of each sensor A and B are provided. E ₂ and the light receiving units R ₁ and R ₂ are arranged so as to be located on the same surface side. Here, the width direction of the photoelectric sensors A and B is the X axis, the length direction is the Y axis, and the direction perpendicular to the working surface is Z.
Define the coordinates as axes.

The light emitting section (E ₁ , E ₂ ) and the light receiving section (R
₁ , R ₂ ) are light emitting elements such as light emitting diodes,
Although it is constituted by a light receiving element such as a phototransistor, an optical fiber may be used for each part. In this case, in FIG. 1, the tip of the optical fiber is positioned at the position of the light emitting units E ₁ and E ₂ and the light receiving units R ₁ and R ₂ , and the light emitting element and the light receiving element are arranged at the base end of each optical fiber. By appropriately setting the length of the optical fiber, the two photoelectric sensors A and B are not limited to the positions shown in FIG.

The detection distance of each photoelectric sensor is set to be different from each other. That is, the first photoelectric sensor A
Light entering the light-receiving portion R ₁ out of the light emitting unit E ₁ is the position (detection point) D _1, which hit the object W to be detected in the light receiving portion exit from the light emitting unit E ₂ of the second photoelectric sensor B R Unlike light entering the ₂ and the position (detection point) D ₂ which hits the object W to be detected, in the example shown, a photoelectric sensor a, the distance from the working surface of the B to the first detection point D ₁ is , it is set longer than the distance to the second detection point D _2. Assuming that the difference between the distances (Z-axis direction) is d, this indicates a designated distance range for detecting that the object exists in a predetermined range.

According to the photoelectric detecting device 1 having the above-described structure, the object W is located farther than the detection point D _{1 of the first} photoelectric sensor A on the working surface side of the photoelectric sensors A and B, as shown in FIG. In some cases, both photoelectric sensors A and B are OFF
(Non-detection state), the detection point D ₂ of the light reflecting portion of the object W (e.g. the edge of the workpiece) is a detection point D ₁ of the first photoelectric sensor A second photoelectric sensor B
When the first photoelectric sensor A is turned on (detection state), the second photoelectric sensor B is turned off (non-detection state), and the object W is moved from the detection point D _{2 of the second} photoelectric sensor B Are also close, both photoelectric sensors A and B are ON (detection state).

Therefore, it can be determined whether the object W is at a position farther from the photoelectric detector 1, a predetermined position, or a closer position, depending on whether one or both of the two photoelectric sensors A and B are ON or OFF.

The photoelectric detecting device 1 includes means for judging the above-mentioned status from the outputs of the photoelectric sensors A and B, and outputting a signal indicating the result. As such means, an electronic circuit configured to determine an output state of the photoelectric sensors A and B and generate a status signal corresponding to any of the above (based on the result thereof, if necessary, A circuit that amplifies the output of each photoelectric sensor), or a CPU that stores a program for performing such a function can be used.

If the first photoelectric sensor A is the "limited reflection type" sensor in FIG. 1, the two photoelectric sensors A and B are both OFF in the above case. Irrespective of the output of the second photoelectric sensor B, detection is possible only by turning on the output of the limited reflection type photoelectric sensor A. The detection can be performed only by turning on the second photoelectric sensor B. In this configuration, since the “limited reflection type” sensor capable of setting the detection range is used, more stable and accurate detection can be performed than when two “direct reflection type” sensors are used.

In the case where two photoelectric sensors A and B are arranged adjacent to each other in parallel with each other as in the above embodiment, FIG.
As shown in the figure, the photoelectric sensors A and B may be inclined so that the detection points D ₁ and D _{2 of} each photoelectric sensor are located on the boundary surface (surface in the Z-axis direction) 2 between the sensors A and B. . Accordingly, in the direction (lateral direction) perpendicular to the boundary surface 2, there is no deviation (difference) between the detection points D ₁ and D _{2 of} both sensors, so that even when a small object or a thin object is detected,
Does not cause detection errors.

Next, FIG. 4 shows an example of use of the photoelectric detection device. This is a robot device that holds and conveys a cylindrical or disk-shaped work Wo by a fork F of a mounted effector provided at the tip of a hand unit (not shown) and transfers it to a predetermined mounting unit. In the above, the position of the work Wo which may be stored at an angle to the work mounting surface of the fork F is detected using the photoelectric detection device 1 of the above embodiment while avoiding the collision between the work Wo and the fork F. Then, the fork F is moved to a position suitable for mounting the work Wo. In this example, photoelectric detection devices 1a and 1b are provided on the left and right of the tip of the fork F.

In operation, the robot device moves the fork F to a position near the work Wo under the control of a computer for controlling its operation. At this time, the photoelectric detection device 1a or 1b detects that it has reached a predetermined position near the work Wo. Thereafter, the fork F is raised, and the work W is detected from the detection output of the photoelectric detection device 1a or 1b.
The position (height) of o in the Z direction is detected. Further, the fork F is advanced in a stepwise manner, and the position of the work Wo in the Z direction is detected from the detection outputs of the photoelectric detection devices 1a and 1b. The operation of lowering the fork F until the work Wo is at an appropriate distance while avoiding collision of the fork F is repeated. Thereby, the fork F can be moved to a position suitable for mounting the work while avoiding collision between the fork F and the work Wo.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a state in which the position of an object to be detected is detected in three states by a photoelectric detection device according to an embodiment.

FIG. 2 is a diagram showing the principle of detecting the position of an object in three different states.

FIG. 3 is a diagram showing a case where two photoelectric sensors are arranged so as to be inclined such that respective detection points are located on a boundary surface between the two sensors.

FIG. 4 is a diagram illustrating an example of a usage state of a photoelectric detection device.

FIG. 5 is a diagram showing the principle of object detection by a conventional “reflective” photoelectric sensor.

FIG. 6 is a diagram showing a detection area of a “limited reflection type” photoelectric sensor.

[Explanation of symbols]

W: Object, W _O : Work, 1: Photoelectric detector, 2: Boundary surface, A, B: Photoelectric sensor, E: Light emitting unit, R: Light receiving unit, D
₁ , D ₂ ... detection point.

Claims (2)

[Claims] 1. A photoelectric device comprising two photoelectric sensors whose respective detection distances are set to be different from each other, wherein the light emitting and light receiving portions of each photoelectric sensor are located on the same surface side. Detection device. 2. The photoelectric detection device according to claim 1, wherein said two photoelectric sensors are arranged such that their detection points are located on a boundary surface between them. apparatus.