JPH01306093A - Follow-up method for working line - Google Patents

Abstract

PURPOSE:To clarify a necessary image and to improve follow-up accuracy by making pattern light beams stronger in intensity than illumination light beams, shutting off the illumination light beams in taking in a picture image on the surface of a work piece and stopping the of irradiation the pattern light in taking in a picture image data on the surface of the work piece. CONSTITUTION:The pattern light beams are made stronger in intensity than the illumination light beams and the level of a 1st threshold value is set to a level between the picture image level of the image of the pattern light beams and the picture image level of the image of a working line. Then, the level of a 2nd threshold value is set to a level lower than the picture image level of the image of the working line. Then, when the picture image on the surface is taken in as specified pattern light beams irradiate from an irradiation means of pattern light beams the surface of the work piece, the illumination light beams are shut off. When the picture image data on the surface is taken in, the irradiation of the pattern light beams are stopped. In this way, only images necessary in detection of both the position of the image of the pattern light beams and the position of the working line can be clarified.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention is a method for operating a predetermined machine tool (for example, an industrial robot) by following a work line attached to the surface of a workpiece. Concerning line following method.

(Prior Art) A cutting robot capable of cutting a workpiece having a complicated three-dimensional shape, such as a press-formed sheet metal, into a desired shape was filed by the present applicant and disclosed in Japanese Patent Application Laid-Open No. 57-1998. Various robots, such as the plasma cutting robot disclosed in Japanese Patent No. 96791, have already been proposed and put into practical use.

In such a robot, it is necessary to manually mark processing lines such as cutting lines on the workpiece or teaching model in advance, and to perform teaching along these marked lines.

As five methods for automatically teaching along such machining lines, there is, for example, the method disclosed in Japanese Patent Application Laid-Open No. 100808/1983. In this method, as shown schematically in FIG. 11, three or more spot light sources 101 to 1 are provided near the end effector of the robot.
03, and capture images of light spots P1 to P3 irradiated onto the surface of the workpiece W from these spot light sources 101 to 103 with the TV right camera 04. And CEL'F
The relative spatial relationship between the robot and the workpiece W is determined based on the positional relationship of the light spots P1 to P3 on the screen (not shown), and the posture of the robot is adjusted accordingly. Further, in this state, an image of the score line C is captured, the robot is moved to follow the position of the score line C, and teaching data is taken in.

Therefore, in this method, there are two types of illumination light: three or more spot lights and illumination light (not shown) that illuminates a certain range on the work surface at once in order to illuminate the image of the score line C. The light is irradiated onto the work surface. However, the first
As shown in Figure 2, when the original spot (for example, Pl) exists on the score line C, the image of the score line C and the spot light P
Image 1 overlaps with image 1. For this reason, it becomes difficult to distinguish these two types of images, and if the brightness of the image of the score line C increases for some reason, this difficulty becomes even thicker (as a result, the tracking There was a problem that there was a limit to the accuracy of the operation.To solve this problem, the intensities of the two types of light were made different, and multivalued image processing 7
However, multi-level image processing devices have the disadvantage of being expensive.

Such a problem is common not only when teaching a robot but also when making a machine tool follow a machining line using optical means.

(Problems to be Solved) The present invention is intended to overcome the above-mentioned problems in the prior art, and is capable of producing images of patterned light such as spot light without using an expensive device such as a multilevel image processing device. An object of the present invention is to provide a machining line tracking method that can clearly distinguish between the image of the machining line and the machining line image, and thereby improve the tracking accuracy without causing a significant increase in cost.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides [F] a method of applying a predetermined pattern of light to the surface of the workpiece from a pamen light irradiation means attached to a predetermined machine tool. Capture image data of the surface in the irradiated state, compare the level of the image data with a first threshold value, determine the position of the image of the pattern light on the surface, and determine the position of the image of the pattern light on the surface. a first step of adjusting the wall-to-wall relationship between the machine tool and the surface of the workpiece based on the position; A second step of capturing image data of the surface while illuminating the surface with illumination light, and comparing the level of the image data with a second threshold value to detect the position of the image of the work line. and (i) changing the spatial relationship between the machine tool and the workpiece along the direction in which the work line extends, the first to third steps By repeating the following, (a) the intensity of the pattern light is made larger than the intensity of the illumination light, and (b) the The first threshold is set to a level between the image level of the pattern light image and the image level of the processing line image, and the second threshold is set to a level between the image level of the processing line image. (e) When capturing image data of the surface with the pattern light irradiated onto the surface of the workpiece in the first step, the illumination light is set to a level lower than the image level. Keep it shut off. (d) When capturing the image data of the surface in the second step, the irradiation of the pattern light is stopped.

Note that the term "workpiece" in this invention is not limited to the product itself, but also includes dummies and other objects representing the workpiece, such as robot teaching models.

Further, the operation of the machine tool may be various operations such as an operation for data acquisition such as teaching, an actual machining operation itself, and an operation of manually moving the tool.

(Embodiment) FIG. 1 is a schematic perspective view showing the mechanical configuration of a rectangular coordinate laser cutting robot as an example of a machine tool that follows a score line (work line) to which the present invention is applied. In the same figure, this laser cutting port RB has a movable table 2 on a base 1 that is movable in the X direction (horizontal direction) by a motor M1 (not shown). work (not shown)′? : Place it. A beam 4 is installed on the top of the column 3 installed perpendicularly on both sides of the base 10, and this beam 4 has a beam 4 that extends in two directions (vertical direction) in the figure and is movable in the Y direction by a motor M2. A moving column 5 is provided.

A light source device 14 incorporating two types of light sources, which will be described later, is attached to the moving column 5.

Furthermore, a motor M4 is provided at the lower end of the moving column 5, and is moved up and down in two directions by a motor M3. As a result, the arm 6 provided eccentrically from the central axis of the moving column 5 rotates in the longitudinal direction of the figure. Also,
A motor M5 is provided on the side of the lower end of the arm 6, and the laser torch T serving as an end effector is rotated in the ψ direction in the figure. Furthermore, adjacent to this laser torch T, a sensor head 8H (described later) for optically following the marked line is arranged.

Of these, a laser beam from a laser oscillation device 7 is applied to the laser torch T through a laser guide pipe 8. ? In addition, the control device 9 has a built-in image processing device, a microcomputer, etc., which will be described later, and an operation panel 1.
0 is provided with a keyboard, a display, etc. Furthermore, the external computer 11 is for performing various types of human output and data processing, and is
It is equipped with a keyboard 13, etc. The image from the sensor head SR is monitored on this CRT 12.

FIG. 2 is a schematic diagram of the electrical configuration of the robot RB shown in FIG. 1. In FIG. 2, the following devices are connected to a microcomputer 21 built into the control device 9 via a bus BL.

■The above motors M1 to 85 and these motors M1 to 81
Mechanism drive system 23° ■ Laser oscillation device 7° ■ Operation panel 10° ■ External computer 11° ■ Light source device 14 On the other hand, in the sensor head 81 facing the workpiece W as a workpiece, illumination light for illuminating the workpiece W and illuminating the marked lines C during teaching is provided by an illumination light source 24 or an electromagnetic shutter 28. and the optical fiber 26.Also, provide a spot light that is used once to maintain the relative distance/posture relationship (spatial relationship) between the sensor head SH and the workpiece W in a predetermined relationship during teaching. The light for this purpose is also provided to the sensor head SH via a laser diode light source 25 or an optical fiber 27.

Note that the microcomputer 21 also receives an operation signal for opening and closing the shutter 28 .

Furthermore, the image signal near the ruled line C is taken into the image processing device 22 from the sensor head SH, and under the control of the microcomputer 210, it becomes (Jl,' shown in 4T12) in FIG. There is. However, image processing device 2
2 is configured as a device that performs two image processings.

Note that this system can also be operated under the control of an upper host system (not shown).

FIG. 3 is a partial sectional view showing details of the single sensor head SH described above, and FIG. 4 is a sectional view taken along line A-A. In these figures, the sensor head SH is provided in parallel with the laser torch T, and at the time of teaching 77, the laser torch T is rotated 90° from the direction shown in the figure in the α direction and retreated.

Meanwhile, in the reproduction mode, the laser torch 'r is returned to the direction shown in the figure, and the sensor head SH is rotated 180 degrees in the γ direction (same as the α direction) and retracted. Furthermore, in this playback mode, the laser torch T and sensor head S
The laser torch T can be moved to the illustrated position of the sensor head SR by rotating R by 180 degrees in the β direction around the axis of the arm 6. These rotations may be performed manually or by a motor. Note that the one broken line shown below the sensor head S11 in FIG. 3 indicates a position corresponding to the tip of the laser torch 'r during rotation in the β direction.

3 and 4, the lower end of the housing 30 of the sensor head SH has three original fibers 26 (
26a to 26C) are provided. and,
From this light emitting end, the area G? on the surface of the workpiece W? 0: Illumination light for planar illumination is irradiated. In addition, three optical fibers 2γ (27a to 270) are connected to the laser diode "/l, and the coefficient z5 is connected to three optical fibers 2γ (27a to 270). The surface of the workpiece Wc) is irradiated from these projectors 318 to 31G as three spot lights.

These floodlights 31a to 31C are arranged so that the spotlights La-Lc from them intersect at a point 0, as shown in FIG. 5, and the relative distance and posture between the sensor head Sfi and the work W. The following Jl,') light spot group is formed on the workpiece W according to the relationship.

That is, when the sensor head 8H maintains a predetermined distance and posture from the surface of the workpiece W by 0.degree. C. (when the surface indicated by Wa in FIG. 5 is the surface of the workpiece W), , as shown in FIG. 6(ll), the three optical spots PI to P3 on the workpiece W are located at the reference position tltQt-
Each is formed within Qa. On the other hand, when these relative distances and postures deviate as shown by Wb-Wd in Fig. 5, they deviate from the reference positions Q, ~Q3, as shown in Figs. 6(b) to (d), respectively. Become something.

Therefore, the optical spots P1 to P30 and the reference position Q
If distance and attitude control is performed so that the relationships between 1 to Q3 are always as shown in FIG. Be able to do it. Such control is
This can also be done by operating the keyboard 12 while visually viewing the screens c and a'r 12.
It is also possible to have the microcomputer 21 perform this automatically based on the output.

Returning to FIG. 3, the surface image of the workpiece (Wo) illuminated by the illumination light from the optical fibers 268 to 26C (in particular,
The images of the lines on the surface of the workpiece W) and the distance/posture detection lights Pl to P3 formed on the surface of the workpiece W by the projectors 31a to 31G are provided in the housing 30 and transmitted through the lens 32. , COD image sensor (I 'l'
V camera) 33, and an image is formed on its surface. 1, as described later, the spot light LB-Lc repeats blinking as the tracking progresses.Second, the light spot/Pl-P
Image 3 forms only at a specific time (details will be explained later)
.

Note that since the illumination light is emitted when the spot lights La to Lc are off, the image level of one house of the ruled line is relatively high at this time. In addition, when the spot lights La-Lc are on, they are blocked, so the image level of the ruled line image is very low at this time (details will be described later). The image data obtained in this manner is supplied to the image processing device 22 of FIG. 2 through the image transmission line 34, and undergoes image processing as described below. As a result, while detecting the pre-formed score line C as an image, the sensor head SH moves to follow it and the teaching data is taken in.

Therefore, below, the process when performing a teaching operation using such a device will be explained with reference to FIG. Note that each of the following processes is performed under the control of the microcomputer 21 and external computer 11 in FIG.

First, in step S1 of FIG. 7, the laser diode light source 25 is turned on. Further, the illumination light source 24 is also turned on and the shutter 28 is closed. As a result, only the spot lights La-Lc are irradiated. Therefore, as shown in FIG. 8e), the images of the spot lights P1 to P3 and the line C
image can now be observed on the surface of the workpiece W. However, the image of the score line C has very low brightness, and depending on the case, it may be hardly observed.

If the illumination light is not blocked, the brightness of the image of the score line C may still be lower than the images of the spot lights P1 to P3, but it may become quite large depending on the surrounding situation. . Note that the mark image (white circle) indicating the reference position Ql-Q8 is created in the image processing device 22, and is combined with the actually observed image and displayed on the CRT 12.
is displayed on the screen.

Among the image data read in such a state,
The image level of the pixel on line I-i in FIG. 8(a) is shown in FIG. 9(a). As can be seen from FIG. 9(a), a peak is formed in the image level in the area corresponding to the original spot P3 and the score line C.

In the next step S2 in FIG.
A first threshold value vH that is predetermined according to the intensity of is set in the image processing device 22. This first threshold VH is set to a level between the image level of the light spots P1 to P3 and the image level of the image of the ruled line C. In other words, this threshold value Vl (is
) has a value intermediate between the two peaks. Also, this first
The threshold value VH is a second threshold value V for detecting ruled lines, which will be described later.
Since the spot light La-Lo is provided by light emission from a laser diode, its light intensity is large, whereas the illumination light source 24 for providing illumination light is a relatively small one such as an incandescent lamp. It is compatible with the use of light sources with high light intensity.

In the next step S3 in FIG. 7, image data (FIG. 9(a)) captured by the CCD image sensor 33 is taken into the image processing device 22. Then, in step S4, the level of each pixel of this image data is compared with the threshold value VH, and based on this, the image data? : Binarize and identify the positions on the screen of pixels with a level higher than the threshold value VH.

This makes it possible to know the positions of the light spots P1 to P3 in FIG. 8(a) on the screen. By the way, since the light intensity of the illumination light is smaller than that of the spot light La-Lb,
Normally, the image data corresponding to the score line C does not exceed vH, but sometimes depending on the surrounding conditions, C0),
If this happens, it may be confused with the light spot Pl-P3. At this moment, the illumination light is blocked and the brightness of the ruled line C is made as low as possible. Furthermore, the positions of the light spots P1 to P3 obtained in this way,
A drive command signal is given to the mechanism and drive system 23 of the robot box B so that the deviation from the reference positions Q1 to Q3 is zero.

As a result, the robot RB is driven, and the light spot P1
~P3 coincides with the reference positions Q1 to Q3, respectively, and the distance between the sensor head SH and the workpiece W and the posture of the sensor head SH are controlled (step 85).
. The image after such control is shown in Figure 8(b).
Furthermore, the image level on the line ``--'' is shown in FIG. 9(1)).

In the next step S6 in FIG. 7, the laser diode light source 25 is turned off and the shutter 28 is opened.

As a result, the irradiation of the spot lights La to Lc is stopped,
Only the illumination light that illuminates the entire field of view of the CCD image sensor 33 is irradiated onto the surface of the workpiece W.

Then, as shown in FIG. 8(C), an image of only the score line C comes to be observed. At this time, the spot light La~
Since Lc is turned off, the light spots P1 to P3 as shown in FIGS. 8(a) and 8(b) are not observed.

The image level on the l-111 line in FIG. 8(e) is as shown in FIG. 9 (9).

As mentioned above, the intensity of the illumination light is the spot light La=L
It has a small value compared to the intensity of c (・ru.

Therefore, in step S7 of FIG. 7, the relatively low second
Threshold value VL? : Set in the image processing device 22.

The level of this second threshold VL is lower than the image level (peak value) of the image of the ruled lines C (and higher than the noise level VN. Then, in the next step S8, as shown in FIG. ), and in step S9, the low level threshold value VL (FIG. 9(C)) is compared with the image level of each pixel, and the image data is binarized. Although the positions of pixels having a level equal to or higher than the threshold value VL are specified, the positions of these pixels correspond to the positions of the ruled line C. In this process, the spot lights La to L(
Since the irradiation of . is stopped, only the image of the score line C is extracted by comparison with the threshold value VL.

In the next step 81o, as shown in FIG. 8(C), the position of the target point F is determined as the point where a predetermined number (8) of scanning lines on the screen intersect with the ruled line C. , these target points F are displayed as +j marks on the screen.These target points F are points that are candidates for teaching points.

Then, in step S11, it is determined how far a point selected from among the plurality of target points F according to a predetermined rule deviates from the center of the screen. Then, according to the amount of deviation, correction is made to the current position/orientation data of the sensor head 81H, and the corrected position/orientation data is taken in as teaching data. This completes the teaching process at one teaching point.

If that point is not the final teaching point, the process proceeds from step 812 to step 813, and the sensor head SR is moved by a predetermined distance along the direction in which the score line C extends. Then, the process returns to step S1, and the above-described one operation is repeated, and when the final teaching point is reached, the teaching process is completed. As a result, the sensor head 8H automatically follows the score line C, and automatic teaching is executed.

In this iterative process, the sensor head 81() position and
When adjusting the posture, only the spotlights La and LC are extracted by the high-level threshold value Vl. Also, when detecting the position of the score line C, only the illumination fL is irradiated. Therefore, when identifying the positions of the light spots P1 to P3, the images of the light spots P1 to P3 and the image of the ruled line C are observed simultaneously, resulting in image data having a spatial level distribution as shown in FIG. 10(a). Even if the original spot P3 is captured, only the image of the original spot P3 can be extracted.

In addition, when determining the position of the image of the score line C, the spot light La- for forming 1 to P3 is used.
Since Lo is turned off, image data like that shown in Figure 10 (a) is not captured, and only the image of the ruled line C can be clearly captured as shown in Figure 10 (b). It is possible. Therefore, the sensor head 8
H will follow accurately.

Note that when detecting the ruled line C, a technique of irradiating only illumination light as described above and irradiating only spot light may also be considered. In this case, both images can be binarized using a single threshold (for example, the threshold L).

However, in the case of such a technique, the illumination light for full-surface illumination must be repeatedly blinked.

However, incandescent lamps and halogen lamps used as illumination light sources have a slow blinking response speed, and repeated blinking has a significantly shortened lifespan.In contrast, in this invention, the illumination light is The spot can be formed using a light source such as a laser diode, which has high blinking responsiveness and whose lifespan is very short even after repeated blinking. There is also the advantage that such a problem does not occur when only the light (pattern light) is blinked.

Although one embodiment of the present invention has been described above, the present invention is not limited to the second embodiment, and for example, the following modifications are possible.

■The processing line is not just a scribing line, but may also be a strip of fluorescent paint applied to the surface of the workpiece W and scribing on it (゛.

In this way, the ruled lines appear more clearly on the image, making it more suitable for automatic tracking.

-! Alternatively, it may be a processing line drawn with paint on the surface of the workpiece W, or a tape may be pasted and a thin cutout may be provided on the tape.

(2) The above embodiment shows the case where three spot lights are used as the pattern light, but γ may be one using four or more spot lights. Also, rather than spot light,
For example, light having a linear or mesh pattern is irradiated onto the surface of the workpiece, and the spatial relationship between the workpiece and the sensor head is adjusted based on the image. The present invention is also applicable to the case of It is not essential to attach the light source of the illumination light to the processing equipment such as a robot (although it may be provided at an external location.Also, the shutter is not limited to an electromagnetic type, and may be one using a liquid crystal. .

■When following the machining line, it is sufficient to change the relative spatial relationship between the sensor head and the workpiece, so the sensor head is spatially fixed and only the position and orientation of the workpiece W side is changed. This invention can also be applied to equipment.

(2) The present invention is applicable not only to robot teaching but also to all kinds of machine tools that perform desired processing while following marked lines.

(Effect of the invention) As explained above, according to this defense, the detection of the position of the image of the pattern light and the detection of the position of the machining line are performed in two ways.
This is done through value image processing, and since it is possible to clearly capture only the images that are essential for both detections, it is possible to improve tracking accuracy without incurring a significant increase in cost. A processing line following method can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing the mechanical configuration of an embodiment of the present invention suitable for teaching an industrial robot; FIG. 2 is a schematic block diagram showing the electrical configuration of the robot shown in FIG. 1; Fig. 3 is a partial sectional view showing the detailed configuration of the sensor head, Fig. 4 is a sectional view taken along line A-A' in Fig. 3, and Figs. 5 and 6 are the relative distances and postures between the sensor head and the workpiece. FIG. 7 is a flowchart showing the operation of the embodiment, FIG. 8 is a diagram showing an example of an image captured in the embodiment, and FIGS. 9 and 10 are images captured in the embodiment. FIGS. 11 and 12 are diagrams illustrating the relationship between the level of image data to be processed and the threshold value. FIGS. RB...Laser cutting robot, 9...Control device, 10...Operation panel, 11
...External computer, 22... Image processing device, T... Laser torch, S
H...sensor head, W...work, C...
Scratch line (processing, ri, "fL~L...Spot light (pattern light), P1
~P3...Light spot, L...Illumination light, V L
, (...first threshold value, VL...second threshold value

Claims (2)

[Claims] (1) Capturing the image data of the surface while irradiating the surface of the workpiece with a predetermined pattern light from a pattern light irradiation means attached to a predetermined machine tool, and comparing the level of the image data and the first A first step of determining the position of the patterned light image on the surface by comparing the patterned light image with a threshold value, and adjusting the spatial relationship between the machine tool and the workpiece surface based on the position of the patterned light image. capturing image data of the surface while irradiating the surface with a predetermined illumination light that illuminates an image of the work line attached to the surface of the workpiece, and adjusting the level and level of the image data. a second step of detecting the position of the image of the work line by comparing the position with a threshold value of 2, and changing the spatial relationship between the machine tool and the workpiece along the direction in which the work line extends; by repeating the first to third steps,
In the work line tracking method of operating the machine tool following the work line, the intensity of the pattern light is made greater than the intensity of the illumination light, and the first threshold value is set to a value of the image of the pattern light. The second threshold value is set to a level between the image level and the image level of the image of the processing line, and the second threshold is set to a level lower than the image level of the image of the processing line. In the first step, when capturing an image of the surface of the workpiece with a predetermined pattern of light irradiated onto the surface of the workpiece from the patterned light irradiation means, the illumination light is blocked, and the second A work line following method, characterized in that when capturing image data of the surface in the step, irradiation of the pattern light is stopped. (2) The machine tool is an industrial robot, the tracking is a tracking for teaching processing of the industrial robot, the work line is a ruled line, and the pattern light has different irradiation angles. There are three or more spotlights having the following characteristics. A work line tracing method according to claim 1.