JPH0453636A - Screw setting device - Google Patents

Abstract

PURPOSE:To keep off any bad effect due to the inclination of a clamped member by operating each distance among plural clamping parts on an image on the basis of the image secured by an image pickup device, comparing it with reference data, and judging an inclined value between one plane and a reference plane of the clamped member. CONSTITUTION:A TV camera 16 is set up tight in the upper part of an assembling position, and a cap part 10 (a clamped member) is photographed from an almost vertical direction and an image signal SS showing the plane image is fed to an image processor 18 which detects a position of the cap part 10 and an attitude around a center line, while it judges the inclined value, and when this inclined value is smaller than the allowable value, a data signal SX showing the position and attitude of the cap part 10 is outputted to a robot controller 20, through which screw tightening work for the cap part 10 is carried out with a robot 26. Mutual distances a', b', c' of three hole images 22 on an image P are measured, comparing the measured value with the reference data prestored in a read-only memory (ROM) or the like, thus the inclined value is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a screw mounting/unloading device for tightening or loosening a screw member with respect to a fastening portion of a fastened member, and in particular, to a device for determining the amount of inclination of a fastened member. This invention relates to a screw loading/unloading device that has the function of

BACKGROUND TECHNOLOGY A screw loading/unloading device is used, for example, for tightening or loosening a screw member with respect to a fastening portion by placing a loading/unloading tool facing a plurality of fastening portions provided in one plane of a fastened member. It is widely used in various automatic assembly lines, etc., such as automatically attaching to hubs. One type of screw attachment/removal device includes: (a) the member to be fastened, which is arranged so that the above-mentioned plane substantially coincides with a predetermined reference plane, from a direction substantially perpendicular to the reference plane; an imaging device that captures an image, and (b
) position detection means for detecting the position of the fastening portion based on an image obtained by the imaging device; and (C) position detection means for detecting the position of the fastening portion based on the image obtained by the imaging device; Some devices include a moving device that moves the attachment/detachment tool relative to each other, so that the positioning of the fastened member and the attachment/detachment tool is automatically performed. The device described in Japanese Utility Model Application Publication No. 64-9886 is one example.

Problems to be Solved by the Invention However, such conventional screw attachment/removal devices are based on the assumption that one plane of the fastened member and the reference plane substantially coincide with each other. If the fastener is tilted, the position of the fastener cannot be detected correctly and the mounting/removal tool may interfere with the fastener, or the threaded member may be strained when the threaded member is inserted or removed, resulting in damage to the threaded member or There were problems such as damage to fasteners and poor tightening.

The present invention has been made against the background of the above circumstances, and its purpose is to prevent the above-mentioned disadvantages caused by the inclination of the members to be fastened.

Means for Solving the Problems In order to achieve this object, it is sufficient to be able to determine whether or not the fastened member is inclined with respect to the reference plane, and the present invention provides the above (a) imaging device. and (b) a plurality of predetermined fastening portions on the image based on an image obtained by the imaging device in a screw mounting/removal device having (a) a position detection means; and (C) a moving device. (e) comparing the distance between the fastening parts determined by the distance calculating means with reference data stored in advance corresponding to the actual distance between the fastening parts; The present invention is characterized in that an inclination determining means is provided for determining an amount of inclination between one plane of the member to be fastened and the reference plane.

Operation and Effect of the Invention In other words, in order to detect the position of the fastened parts, the distance between a plurality of fastened parts is calculated from the image obtained by the imaging device, and the distance between the fastened parts is calculated on the image when the fastened members are correctly arranged. The amount of inclination of the member to be fastened is determined by comparing the reference data corresponding to the actual distance between the fastened parts, such as the distance between the plurality of fastened parts, with the distance determined from the image. Then, based on this determination result, for example, by resetting the fastened member correctly or moving the attachment/detachment tool relative to the fastened member so that it is in its correct position, it is possible to correct the problem caused by the inclination of the fastened member. It is possible to prevent the occurrence of damage and defects in tightening. This reduces the incidence of defective products and improves the reliability of the product, and also increases the operating rate of the device and improves the efficiency of mounting and removing screw members.

Furthermore, in the present invention, since the amount of inclination is determined based on the image captured by the imaging device in order to detect the position of the fastening portion, there is no need for major design changes compared to conventional devices. There is the advantage that the device can be constructed simply and inexpensively.

When determining the amount of inclination mentioned above, the closer the object is to the imaging device, the larger the dimension in the image will be, and the greater the amount of inclination, the smaller the distance in the inclination direction will be. The amount and direction of inclination can be determined by determining the difference with the dimension at multiple locations in the image.

The direction of inclination can be used, for example, when automatically aligning the fastened member and the attachment/detachment tool.

EXAMPLE Hereinafter, an example of the present invention will be described in detail based on the drawings.

In FIG. 1, reference numeral 10 denotes a flat disk-shaped cap component as a member to be fastened, and as shown in detail in FIG. 2, three tapped holes 12a, 12b,
2c (Hereinafter, if there is no particular distinction, simply refer to the screw hole 12.
) is the dimension a.

It is located at the apex of a triangle whose three sides are lengths b and c. This cap part 10 is attached to a predetermined position of the workpiece base 14 transported to the assembly position by an operator's hand in a substantially horizontal posture.
When installing, the position or phase around the center line may vary, or it may be tilted up or down due to uneven contact. In this embodiment, the flat cap part 10 itself corresponds to one plane, and the substantially horizontal plane located when the cap part 10 is correctly attached to the workpiece base 14 corresponds to the reference plane.

A robot 26 is disposed near the assembly position. This robot 26 is equipped with a bolt runner 28 at its tip, in which three rotary sockets are arranged corresponding to the screw holes 12, and a robot control unit is supplied with a data signal SX representing the position and orientation of the cap part 10. The operation of the bolt runner 2 is controlled by the device 20.
8 is held in a substantially vertical position and moved in parallel in a substantially horizontal plane to face the cap part lO, and the bolt runner 28 is rotated around the center line to rotate each rotating socket holding a bolt into three The screw holes 12 are arranged to face each other substantially concentrically. Then, by lowering the bolt runner 28 while rotating the rotary sockets in this state, the bolts are respectively screwed into the three screw holes 12 of the cap part 10 and tightened. The robot control device 20 and the robot 26 correspond to a moving device, and the bolt runner 28 corresponds to an attachment/detachment tool.

On the other hand, above the assembly position, a TV left camera 6 as an imaging device is arranged in a fixed position, and captures an image of the cap component 10 from a substantially perpendicular direction and generates an image signal SS representing a planar image of the cap component 10. It is supplied to a processing device 18. The image processing device 18 includes a microcomputer, and detects the position and orientation of the cap component 10 around the center line based on the image represented by the image signal SS by performing signal processing according to a predetermined program. At the same time, the amount of inclination is determined, and if the amount of inclination is smaller than a predetermined allowable value, the data signal SX representing the position and orientation of the camping part 1O is output to the robot control device 20.

FIG. 3 is a diagram illustrating the signal processing algorithm of the image processing device 18. In step S1, an image signal SS is captured, and in step s2, the position and center line of the cap component 10 are determined based on the image represented by the image signal SS. Detect the posture of the surroundings. Figure 4 shows the image signal S
This is an example of the image P represented by S, and the TV left camera The position of the cap component 10 within the imaging range of 6 is detected, and the large image 2 of the cap component 10 is detected.
The posture of the cap component 10 around the center line is detected from the mutual positional relationship between the two. Whether or not the large image 22 corresponds to the screw hole 12 is recognized based on data representing the diameter and the like of the screw hole 12 stored in a ROM or the like in advance.

Further, the large images 22a, 22b, and 22c correspond to the screw holes 12a, 12b, and 12c, respectively, which are identified from the mutual positional relationship of the three large images 22, and based on this, the cap is The attitude of the component 10 is detected. Of the series of signal processing performed by the image processing device 18, the portion that executes step S2 corresponds to the position detection means.

In the next step S3, it is determined whether or not the position and orientation of the cap component IO have been detected in the step s2. This is because if the parameter adjustment of the image processing device 18 is not appropriate or the positional deviation of the cap component 10 is large, the large image 22 cannot be recognized and the position and orientation of the cap component 10 cannot be detected. This is because there are cases where the detection is not possible, and if the detection is not possible, step s4 is executed. In step s4, it is determined whether or not the position and orientation of the cap component 1o could not be detected in the previous image processing. If YES, the parameters of the image processing device 18 are adjusted in step S5, and then step 5
1 or less executions are repeated. If the determination in step S4 is No, an abnormality display is displayed in step S6 to prompt the user to reset the cap component 1o, and the restart switch is operated after the cap component 1o is reset in step S7. If it is confirmed that the above is true, the execution from step Sl onwards is repeated.

If the determination in step S3 is YES, the distances a, b'', and c' between the three hole images 22 on the image P are measured in the next step S8, and the ROM is etc., and is compared with pre-stored reference data.

This reference data indicates that the cap part 10 is the workpiece base 14
The distances a*, ba, and c* are the distances between the hole images 22 on the image P when the images are taken by the TV camera 16 in the state that they are correctly attached to the hole images, and the distances a', b'', c' are Corresponding reference data am,
The difference between ba and c* is Δa(=a', *), Δb(=b
"-b'") and Δc (=c'-01) are calculated. These differences Δa and Δb.

When ΔC is positive, it means that the portion between the hole images 22 is higher than the reference plane, and when it is negative, it means that it is lower than or inclined from the reference plane.

Further, the image processing device 18 has height data corresponding to the above-mentioned comparative dimension difference stored in advance, and the height data corresponding to the above-mentioned comparative dimension difference is stored in advance, and the height data corresponding to the above-mentioned comparative dimension difference is stored in advance.
0, the height data h, , hb, hc corresponding to the differences Δa, Δb, ΔC are read, respectively, and the distance ra + r from the cap center 0 to the straight line connecting the hole image 22
Using b + r ((see Figure 4), the following formula (1)
The amount of inclination θ is calculated according to the following.

The distance ra+b+rc is determined from the positional relationship of the hole images 22.

θ=jan−'・
(1) Of the series of signal processing performed by the image processing device 18, the portion that executes step S8 above corresponds to distance calculation means, and the portion that executes steps S9 and S10 corresponds to tilt amount determination means.

Then, in the next step Sll, it is determined whether or not the above-mentioned inclination amount θ is smaller than a predetermined tolerance value θ1. A data signal SX representing the posture is output to the robot control device 20, and the robot 26 performs a screw tightening operation on the cap component 10. Also, the amount of inclination θ is the allowable value θ
.

In the above case, step S6 is executed, and after the cap component 10 is reset to the workpiece base 14, the restart switch is operated, and steps 31 and subsequent steps are executed. The allowable value θ1 is set within a range that allows the robot 26 to properly tighten the bolts to the cap component 10.

In the screw tightening device of this embodiment, the amount of inclination θ of the cap part 10 is determined, and if the amount of inclination θ is larger than the predetermined tolerance θ1, the cap part 10 is attached to the workpiece base 14. On the other hand, since the installation is designed to be corrected, troubles such as damage to the bolts caused by the inclination of the cap part 10 and defects in tightening can be prevented, reducing the incidence of defective products and improving product reliability. In addition to improving the flexibility, the operating rate of the equipment is also increased and work efficiency is improved.

In addition, since the above-mentioned inclination amount θ is determined from the image P taken by the TV camera 16 in order to detect the position and orientation of the cap component 10, the signal processing software of the image processing device 18 may be changed or reference data etc. It is only necessary to newly store the information, and the conventional device can be used as is and configured easily and inexpensively.

Although one embodiment of the present invention has been described above in detail based on the drawings, the present invention can also be implemented in other embodiments.

For example, in the embodiment described above, when the amount of inclination θ is large, the cap part 10 is re-centered, but the robot 26 can tilt the posture of the bolt launch 28 from the vertical direction, and There was no abnormality in the attachment of the cap part 10 to the workpiece base 14.
If the posture of the cap component 10 varies, it is also possible to change the posture of the bolt launch 28 in accordance with the amount of inclination θ and the direction of inclination of the cap part 10 to perform bolt tightening.

Further, in the embodiment described above, the bolt runner 28 is moved in accordance with the data signal SX, but the workpiece base 14
You may also move the .

Further, in the above embodiment, the cap part 10 is attached to the workpiece base 14 at the assembly position, the image is taken by the TV camera 16, and the bolts are tightened by the bolt runner 28, but it is preferable to perform these operations at separate stations. It can also be done.

Further, the cap part 10 of the above embodiment is provided with three screw holes 12, but the number of screw holes 12 is set appropriately, and the distance between the screw holes measured when determining the amount of inclination θ is The distance does not have to be 3, but 2 or 4.
There is no problem even if it is more than one place.

In addition, in the embodiment described above, the screw carpenter 2 is used to tighten a bolt, but it is also possible to loosen a bolt screwed into the screw hole 12, tighten a nut to a male screw provided as a fastening part, or tighten a nut to a male screw. The present invention can also be applied to the case of loosening a nut.

Further, in the embodiment described above, the cap part 1o is manually attached to the workpiece base 14, but even when the cap part 10 is automatically supplied, if a supply error such as misalignment or inclination occurs, it is necessary to manually attach the cap part 1o to the workpiece base 14. The screw loading/unloading device of the invention can be suitably utilized.

Further, in the above embodiment, the difference Δa, Δb, ΔC is the inclination amount θ
The difference between them Δa, Δb,
Since ΔC corresponds to the amount of displacement or the amount of inclination from the reference plane, the amount of inclination can also be determined based on whether any one of them exceeds a predetermined allowable range.

Further, in the above embodiment, the cap part 10 is the workpiece base 1
TV camera 16 when properly attached to 4
Distance a between hole images on the image when imaged by
*, b II, and c * are set as the reference data, but the distances a, b, and c between the screw holes 12 in the cap component 10 can also be used as the reference data.

Furthermore, even when the distances a, b, and c between the threaded holes 12 are equal to each other, or when the threaded holes 12 are provided at equal angular intervals on a circumference centered on the center line of the cap component 10, The invention can be applied. In that case, three large images 22
It is not necessary to have a one-to-one correspondence between the screw hole 12 and the screw hole 12, and for example, the posture of the cap part 10 around the center line is 1:1.
Detection may be performed within an angular range of 20 degrees.

Although other examples are not provided, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the configuration of a screw tightening device that is an embodiment of the present invention. FIG. 2 is a plan view of the cap part to be screwed by the apparatus of FIG. 1. FIG. 3 is a diagram illustrating an algorithm of the image processing device in the apparatus of FIG. 1. FIG. 4 is an example of an image represented by an image signal output from a TV camera in the apparatus shown in FIG. S8: distance calculation means 39, SIO: slope determination means

Claims (1)

[Scope of Claims] In order to tighten or loosen a screw member with respect to a plurality of fastening portions provided in one plane of a fastened member by arranging a mounting/unloading tool to face a plurality of fastening portions provided within one plane of a fastened member, the one plane is an imaging device that images the fastened member arranged to substantially coincide with a predetermined reference plane from a direction substantially perpendicular to the reference plane; and A screw attachment/detachment device comprising: a position detection means for detecting the position of a fastening portion; and a moving device for relatively moving the fastened member and the attachment/detachment tool according to the position of the fastening portion detected by the position detection means. In the apparatus, a distance calculating means for calculating a distance between a plurality of predetermined fastening parts on the image based on the image obtained by the imaging device; and a distance calculating means for calculating the distance between the fastening parts determined by the distance calculating means. distance,
The present invention is characterized by comprising an inclination determining means for determining the amount of inclination between one plane of the fastened member and the reference plane by comparing with reference data corresponding to the actual distance between the fastened parts stored in advance. Screw loading/unloading device.