JPS608723B2 - position detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the position of an object, and more particularly, it optically detects the position of an object such as an assembly part, and allows an industrial robot or the like to automatically assemble the parts. It is related to a device that can do this.

2. Description of the Related Art Recently, many attempts have been made to automate the assembly of various assembly parts, the operation of articles, etc. from the viewpoint of saving labor costs through labor saving.

In such cases, a need arises to detect the location of parts or objects (hereinafter collectively referred to as workpieces) that require assembly or manipulation, such as edge layers. Therefore, conventional methods used to detect the edge layer of a workpiece include those using magnetic sensors, ultrasonic waves, and optical sensors. In industrial robots, etc., which have a multi-degree-of-freedom motion mechanism for assembling parts, etc., the hand part performs complex movements. The drawback is that it is not possible to get very close to the workpiece, and accurate position detection cannot be performed.

On the other hand, the method using an optical sensor has the advantage of being able to detect the workpiece even from a position far away from the workpiece, so it is better than the magnetic sensor in that respect. Conventionally, as shown in FIG. 1, a device for detecting the edge layer of a workpiece using an optical sensor has been used to irradiate light from a light source 1 on one side of the workpiece W, and to detect a layer on the opposite side. There is a device that detects the end portion by determining whether the light from the light source 1 reaches the light receiving portion 2 or not. However, in the case of this conventional method, especially for industrial robots that perform complex movements with multiple degrees of freedom, from the light source 1 to the light receiving part 2,
It is clear that various problems arise in implementation due to reasons such as the difficulty of properly delivering light to the device. In order to eliminate such problems, as shown in Figure 2, 1.
A method in which a filter paper consisting of two light sources and one light receiving section 2 is placed on the same side of the workpiece W, and the light emitted from the light source 1, for example, a spot light, is applied onto the workpiece W, and its image is captured by the light receiving section 2. can also be considered.

This method also detects the edge layer depending on whether the light from the light source 1 reaches the light receiving part 2, and although there is a difference in whether it is direct light or reflected light, it is basically an optical sensor method. It is based on common principles. However, the method shown in FIG. 2 is not without problems. That is,
In this method, it is necessary to maintain a certain mounting angle between the light source 1 and the light receiving section 2.
For example, in a device such as a robot hand, the optical axis of the light source 1 and the optical axis of the light receiving section 2 do not match on the workpiece W, and even if they could be adjusted to match, the position of the device with respect to the workpiece W would be If the (posture) is changed, even if the irradiation light from the light source 1 hits the workpiece W, the light will not reach the light receiving section 2 due to the shift of the optical axis. therefore,
Even in the case of the method shown in FIG. 2, it is extremely difficult to detect the edge layer, especially in a device that operates in a complex manner. In other words, the conventional position detection device is configured to detect the position by associating one light receiving element with one light source, so it cannot make complex movements like a robot's hand. The device was unable to accurately capture the reflection of the spot light from the light source, making it extremely difficult to detect its position.

The present invention has been made in order to eliminate the drawbacks of the above-mentioned prior art, and is particularly applicable to devices such as industrial robots that perform complex operations by improving the method shown in FIG. The object of the present invention is to provide a position detection device that can automatically perform the following steps.

In order to achieve this purpose, the position detection device of the present invention irradiates light onto a workpiece (article) from a light source, receives the light at a light receiving section, and detects the presence/intensity of the image of the light on the light receiving section. In a device for detecting the position of a workpiece (article), a light-receiving element group is provided in the light-receiving section, which is a two-dimensional arrangement of multiple light-receiving elements such as an industrial television camera or a semiconductor image sensor. The device compares the movement of the light image between the address detected at that point and the previously detected and stored address, and detects when the difference between the addresses exceeds a certain value. Even if there is a change in the posture of the workpiece and the detection device, the edge layer of the workpiece can be detected reliably and accurately.

Hereinafter, an embodiment in which the present invention is applied to detecting a direct end portion of a workpiece will be further described with reference to FIG. 3 of the accompanying drawings.

As shown in FIG. 3a, the position detection device according to the present invention is roughly divided into a light source 1 and a light receiving section 2. The light source 1 uses a halogen lamp or a xenon lamp, and its light is passed through a lens system 3. Alternatively, the workpiece W is irradiated as a spot light or slit light without passing through it, and the light receiving section 2 receives an optical image of the spot light or slit light formed on the workpiece W.

Therefore, as shown in FIG. 3b, the light receiving section 2 includes a lens system 4 that focuses an optical image of the spot light or slit light produced on the workpiece W by the light source 1 onto a light receiving element group 5, which will be described later. A light-receiving element group 5 in which a plurality of light-receiving elements such as an industrial television camera or a semiconductor image sensor are arranged in a plane, for example, in a matrix, an output clock generating section 6 that generates a read clock, and a light-receiving element group 5 that generates a read clock; a peak value address detection section 7 that detects the address of the part with the strongest signal (the part where the light is the strongest), a fixed position storage part 8 that stores the address of the end layer of the workpiece W, and the address of the spot light at a certain point in time. and the address of the spot light ahead of it (already stored in the localization layer storage section 8).

), and if the two differ by a certain value or more, an address comparator 9 generates an end detection signal. Next, the operation of detecting the end portion history of the workpiece W in this embodiment will be explained step by step.

'1} First, the presence/absence and strength of the spot light or slit light hitting the light receiving element group 5 is sequentially extracted according to the output clock of the output clock generation section 6, and the signal is sent to the peak value address detection section 7.

Incidentally, when the light receiving elements of the light receiving element group 5 are arranged in a matrix as shown in FIG. 3B, address numbers may be assigned in the order of arrangement. ■Next, the peak value address detection section 7 detects the address of the part of the light receiving element group 5 with the strongest signal (light), and sends the peak value address signal to the address comparison section 9 and the localization layer storage section 8. send.

'3} The address comparator 9 compares the address of the current spotlight with the address of the destination spotlight sent from the localization almanac storage unit 8, and if the difference between the two addresses exceeds a certain value, It issues an edge detection signal and also gives a localization almanac change command to the localization layer storage section 8.

■ As a result, a new address (the address output by the peak value address detection unit 7) is newly stored as the localization calendar in the localization layer storage unit 8 at the time when the edge detection signal is output from the address comparison unit 9. Ru.

Note that at the time of first edge detection, since no address is stored in the localization layer storage section 8, the address comparison section 9
does not output an edge detection signal, and the localization layer storage section 8 stores the output signal of the peak value address detection section 7 as it is.
'5- By the above-mentioned operations (1} to [4}, if the spot light moves on the light receiving element group 5, an output signal from the position detection device representing the movement is obtained. Therefore, the light source 1 and light receiving section 2 (light receiving element group 5 and lens system 4
Only .

) is attached to the hand of an industrial robot (not shown), and the hand is moved near the edge of the workpiece W. Since the spot light moves at the edge of the workpiece W, it can be done accurately and reliably. The end of the workpiece W can be detected. Note that the signal according to the intensity of the spot light obtained from the light receiving element group 5 is subject to various disturbances, such as the influence of non-uniformity on the workpiece surface or the influence of external brightness fluctuations. It is possible to provide a processing device between the peak value address detection section 7 and the peak value address detection section 7 to perform integrated averaging, differential processing, etc. of the signal to reduce the influence of disturbance.

Further, in the above embodiment, the present invention was explained as being used for detecting the end of an assembled part, but the present invention is not limited to this, and the present invention can be applied to any device that can optically detect the position. It can be applied to any purpose. As explained above, according to the present invention, a light receiving element group is provided in the light receiving section in which a plurality of light receiving elements are arranged in a plane for one light source, and an image of light on the light receiving element group is provided. By comparing the currently detected address with the previously detected and stored address, and detecting the movement when the difference in addresses exceeds a certain value, the position of the detection device relative to the workpiece can be adjusted. It is possible to perform reliable and accurate position detection even when the position changes, and its performance is fully demonstrated even when installed in devices that perform complex movements with multiple degrees of freedom, such as industrial robots, which was previously impossible. Excellent effects such as the ability to automate relatively complex parts assembly, etc., which previously existed, can be achieved.

[Brief explanation of drawings]

FIGS. 1 and 2 are schematic perspective views showing the prior art, respectively, and FIGS. 3 a and b' are a schematic perspective view showing an embodiment of the position detection device according to the present invention, and a schematic view showing the configuration of the light receiving section, respectively. It is. 1... Light source, 2... Light receiving section, 5... Light receiving element group, 7... Peak value address detection section, 8......
Localization layer storage section, 9...Address comparison section. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. In a position detection device that irradiates light onto an article from a light source, receives the light at a light receiving section, and detects the position of the article according to the presence/absence and strength of an image of the light on the light receiving section, 1
A light receiving element group consisting of a plurality of light receiving elements arranged in a plane is provided in the light receiving part for each light source. A peak value address detection section that detects the address of the part where the light is strongest is connected to the peak value address detection section, and a fixed position storage section that stores the address is also connected to this peak value address detection section. , comparing the spot light from the peak value address detection section at a certain point with the spot light stored in the fixed position storage section,
A position detection device connected to an address comparison section that outputs an end detection signal when the two differ by a certain value or more.