JP2519444B2 - Work line tracking device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a work for operating a predetermined machine tool (for example, an industrial robot) by following a work line attached to the surface of a workpiece. The present invention relates to a line tracking device.

(Prior art and its problems) As 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, the present applicant has filed an application,
Various types such as the plasma cutting robot disclosed in JP-A-57-96791 have already been proposed and put into practical use. In such a robot, it is necessary to manually mark the work line such as the cutting line on the work or teaching model in advance and perform the teaching along the marking line.

Conventionally, teaching work along such a work line has been performed manually, but since this requires a great deal of time and labor, recently, the efficiency of the teaching is improved by an automatic teaching device. Is being pursued. As such a device, for example, JP-A-61-10080
There is a device as disclosed in Japanese Patent No. In this device, as shown in FIG. 9 as a schematic diagram, three or more spot light sources 101 to 103 are provided near the end effector of the robot.
The TV camera 10 displays images of the light spots P _{1 to} P ₃ emitted from the spot light sources 101 to 103 on the surface of the work W.
Capture with 4. Then, the spatial relative relationship between the robot and the work W is obtained based on the positional relationship of the light spots P _{1 to} P ₃ on the screen of the CRT (not shown), and the posture of the robot is adjusted accordingly. Furthermore, in this state, the ruled line C
Of the image, the robot is moved following the position of the marking line C, and the teaching data is taken in.

By the way, in such a device, the image pickup magnification of the TV camera 104 is made considerably large in order to accurately detect the position of the ruled line C. Therefore, the image captured by the TV camera 104 is as shown in FIG. 10, for example, and the ruled line C is a band-shaped image having a finite width. However, in order to handle the position of the ruled line C as numerical data, it is inconvenient to use such a strip image. Therefore, the predetermined number (N)
At the position where each scanning line l _i (i = 1,2, ...) Crosses the marking line C, the designated point F _i (i = 1,2, ...) is automatically set on the marking line C, and this designated point F The position of _i is recognized as the representative position of the ruled line C.

More specifically, the center between the point P _s (hereinafter referred to as the “crossover start point”) at which the scanning line l _i begins to intersect the scribe line C and the point P _e (“crossover start point”) at which the scan line l _i ends. A point is calculated and obtained, and this is designated as a designated point F _i . Then, on the screen of the monitor CRT, the position marker M _i of “+” mark as shown in FIG. 9 is displayed at the position of the designated point F _i .

However, a smooth band image as shown in FIG. 9 is not always obtained as the image of the scoring line C, and it is caused by nonuniformity of the scoring and a threshold value shift in the image binarization process. Therefore, the image of the ruled line C often becomes as shown in FIG. When an image having such unevenness or branching is captured, it becomes difficult to set each pointing point F _i appropriately, and as shown in FIG. A part of the designated point F ₃ is set at a position deviated from.

As a result, the conventional device has the advantage of higher efficiency compared to manual teaching, but when the position data of the designated point F _i is taken in and the follow-up operation is performed, the follow-up operation is performed. There is a problem that the locus does not always become an appropriate one along the ruled line C.

(Object of the Invention) The present invention is intended to overcome the above-mentioned problems in the prior art, and even when the pointing point automatically set with respect to the image of the working line exists at an inappropriate position, automatic tracking is performed. An object of the present invention is to provide a work line tracking device capable of performing an appropriate work line tracking operation without losing efficiency.

(Means for Achieving the Object) In order to achieve the above-mentioned object, the present invention reads an image of a working line attached to the surface of a workpiece to determine a position in a predetermined relationship with the image of the working line. A process for automatically setting a pointing point for instructing the position of the working line, giving motion information determined according to the position of the pointing point to a predetermined machine tool, and causing the machine tool to follow the work line. In the line tracking device, based on the display means for displaying the position of the automatically set pointing point together with the image of the working line, and the manual input given according to the display content of the displaying means, the pointing point is set to the desired point. An instruction point movement correction means for moving and correcting to the position is provided.

That is, in automatic image processing, there is a limit in selecting an appropriate pointing point position from an image of a work line, but it is noted that human shape recognition ability is remarkably excellent. From this viewpoint, in the present invention, the position of the automatically set pointing point is displayed together with the image of the working line, and when the operator determines that the position of the pointing point is not appropriate,
The device is designed to move and correct its position by manual input.

The “workpiece” in the present invention is not limited to the product itself, but is a term that includes a dummy or the like representing a work target such as a teaching model of a robot.

Further, the operation of the machine tool may be various operations such as an actual machining operation itself in addition to an operation for data acquisition such as teaching.

(Embodiment) A. Outline of mechanical structure of embodiment FIG. 1 shows an example of a machine tool for performing marking line (working line) tracking using the working line tracking device of the present invention.
It is a schematic perspective view which shows the mechanical structure of a rectangular coordinate type laser cutting robot. In the same figure, this laser cutting robot
The RB has a movable table 2 which is movable on the base ₁ in the X direction (horizontal direction) by a motor M ₁ (not shown), and a work (not shown) is placed on the movable table 2. Place. A beam 4 is erected on the top of a column 3 which is erected vertically on both sides of the base 1, and the beam 4 extends in the Z direction (vertical direction) in the drawing and is moved in the Y direction by a motor M ₂ . A movable column 5 that is movable is provided. The moving column 5 includes a light source device 14 having two types of light sources, which will be described later.
Is installed.

Further, a motor M _{4 which} moves up and down in the Z direction by the motor M ₃ is provided at the lower end of the moving column 5. Accordingly, the arm 6 provided at a position eccentric from the center axis of the moving column 5 rotates in the θ direction in the drawing. Further, a motor M ₅ is provided on the lower side of the arm 6,
This allows the laser torch T as an end effector.
Rotates in the ψ direction in the figure. Furthermore, this laser torch T
Adjacent to the sensor head for optical marking line tracking
SH (described later) is placed.

Among these, the laser beam from the laser oscillator 7 is applied to the laser torch T through the laser guide pipe 8. Further, the control device 9 has an image processing device, a microcomputer, and the like, which will be described later, built therein.
The 10 is provided with a keyboard and a display.

Further, the external computer 11 is for inputting / outputting various data and processing data, and includes a CRT (display means) 12 and a keyboard (manual input means) 13. And the image from the sensor head SH is
The image on the screen of the CRT 12 is monitored by the CRT 12, but is used for visual observation in the movement correction of the position scale described later. Further, "pointing point movement correction means" according to the features of the present invention is provided as software in the microcomputer 21 or the external computer 11.

B. Outline of Electrical Configuration of Embodiment FIG. 2 is a schematic diagram of the electrical configuration of the robot RB shown in FIG. In FIG. 2, the following devices and the like are connected to the microcomputer 21 built in the control device 9 via the bus BL.

The motor M ₁ ~M ₅ and, (not shown in FIG. 1) encoder E ₁ to E ₅ for detecting the rotation angle of the motor M ₁ ~M ₅
Mechanism drive system 23, laser oscillator 7, operation panel 10, external computer 11, light source device 14.

On the other hand, the sensor head SH facing the workpiece W as the workpiece receives illumination light for illuminating the workpiece W and illuminating the ruled line C from the illumination light source 24 via the optical fiber 26 during teaching. Given. Further, the light for giving the spot light used for maintaining the relative distance / posture relationship between the sensor head SH and the work W in a predetermined relationship during teaching is also transmitted from the laser diode light source 25 through the optical fiber 27. It is given to the sensor head SH.

Further, from the sensor head SH, an image signal in the vicinity of the marking line C is taken in by the image processing device 22 and is displayed on the CRT 12 in FIG. 1 under the control of the microcomputer 21. However, the image processing device 22 is configured as a device that performs binary image processing. This system can be operated under the control of a host system (not shown).

C. Detailed Configuration of Sensor Head SH FIG. 3 is a partial cross-sectional view showing the details of the sensor head SH described above, and FIG. 4 is a cross-sectional view taken along the line AA ′. In these figures, this sensor head SH is a laser torch T
The laser torch T is rotated 90 ° in the α direction from the direction shown in the drawing and retracted during teaching.

Further, in the reproduction mode, the laser torch T is returned in the direction shown in the figure, and the sensor head SH is rotated 180 ° in the γ direction (the same as the α direction) and retracted. Further, in the reproduction mode, the laser torch T and the sensor head SH can be rotated 180 ° in the β direction around the axis of the arm 6 so that the laser torch T can move to the position shown in the sensor head SH. These rotations may be performed manually or by a motor. A broken line I shown below the sensor head SH in FIG. 3 indicates a position corresponding to the tip portion of the laser torch T when rotating in the β direction.

3 and 4, the light emitting ends of three optical fibers 26 (26a to 26c) connected to the illumination light source 24 of FIG. 2 are provided at the lower end of the housing 30 of the sensor head SH. ing. Then, from this light projecting end, illumination light L for illuminating the area G on the surface of the work W in a planar manner is emitted. Further, the light supplied from the laser diode light source 25 by the three optical fibers 27 (27a to 27c) is given to the projectors 31a to 31c having a microlens (not shown) at the tip thereof, and these projectors 31a to 31c. The surface of the work W is irradiated from 31c as three spot lights.

These projectors 31a~31c, as shown in FIG. 5, the spot beam L _a ~L _c from them are arranged to intersect at one point O, the relative distance between the sensor head SH and the workpiece W · The following light spot groups are formed on the work W according to the posture relationship. That is, when the sensor head SH maintains a predetermined distance and posture with respect to the surface of the work W (the fifth
(When the surface indicated by W _a in the figure is the surface of the workpiece W)
6A, the _three light spots P _{1 to} P ₃ on the work W are formed in the reference positions Q _{1 to} Q ₃ , respectively. On the other hand, these relative distances and postures are W _{b in} FIG.
~ When it shifts as shown by W _d , Fig. 6 (b) ~
As shown in (d), the positions are displaced from the reference positions Q _{1 to} Q ₃ .

Therefore, the positions of the light spots P _{1 to} P ₃ and the reference position Q ₁ to
By performing the distance / posture control so that the relationship with Q ₃ is always the relationship shown in FIG. 6 (a), tracking and teaching are performed while maintaining the relative distance between the sensor head SH and the work W and the attitude at predetermined values. You can do Such control is provided by CRT1
The operation can be performed by operating the keyboard 12 while visually observing the second screen, or the microcomputer 21 can be automatically performed based on the output of the image processing device 22.

Returning to FIG. 3, the illumination light L from the optical fibers 26a to 26c
The surface image of the work W (particularly, the image of the marking lines on the surface) and the distance / posture detection light spots P _{1 to} P ₃ formed on the surface of the work W by the projectors 31a to 31c are CC through the lens 32 provided in the housing 30
The light enters the D image sensor (ITV camera) 33 and forms an image on its surface. Then, the image data obtained in this way is given to the image processing device 22 of FIG. 2 through the image transmission line 34 and undergoes image processing as described later. As a result, while detecting the ruled line C formed in advance as an image, the sensor head SH moves following it and the teaching data is taken in.

D. Teaching Operation Therefore, hereinafter, the processing when the teaching operation is performed using such a device will be described with reference to FIG. The following processes are performed under the control of the microcomputer 21 and the external computer 11 shown in FIG. Further, as described above, the spatial relationship between the sensor head SH and the work W is adjusted by the positional relationship between the light spots P _{1 to} P ₃ , but this processing is as described above, and the gist of the present invention is as follows. Since they are not related, duplicate description thereof will be omitted below.

First, in step S1 of FIG. 7, the image of the ruled line C and its vicinity is input from the ITV camera 33. This image data is binarized in the image processing device 22. In the next step S2, the microcomputer 22 calculates the center point position of the portion where each N scanning lines intersects with the marking line C by performing the same processing as that described in FIG. Then, the positions of these center points are set in the memory (not shown) as the positions of the designated points.

In step S3, the pointing point F _i obtained as described above
Position marker M _i (i = 1,2, ...) indicating the position of (i = 1,2, ...)
...) and the image of the ruled line C as shown in FIG. 8 (a).
Display on screen R of CRT12. However, x in FIG.
Indicates the horizontal scanning direction (scanning line direction), and y indicates the vertical scanning (feed) direction.

In this state, the operator visually checks the screen R of the CRT 12 to determine whether the positional relationship between the image of the marking line C and each position marker M _i is appropriate (step S4). In the example of FIG. 8 (a),
It is visually determined that the position marker M ₃ is displaced too much to the right side of the drawing. According to this determination result, in the next step S5, a branch is made according to the propriety of the position of each designated point. If one or more of the designated points F _i is not appropriate, the process proceeds to step S6, and the follow-up operation is temporarily stopped by a key input from the keyboard 13.

In the next step S7, the manual input from the keyboard 13, as well as specify the indication point F ₃ to be corrected, to specify the destination. Of these, designated designated point F ₃ to be modified, for example, allowed to correspond to a predetermined number to each instruction point in the order from the top of the screen R, can be performed by entering its number. To specify the destination, the cursor movement keys (not shown) of the keyboard 13 are used to move the x-direction cursor K _x and the y-direction cursor K _y in FIG. This can be done by designating their intersection Q. Of course, a mouse or the like may be attached to the external computer 11, and the destination position may be specified by using this, or the coordinate value on the screen R may be given as a numerical input. Of course, a light pen can also be used.

When the movement correction data is manually input in this way, the position marker M corresponding to the designated pointing point F _3
3 moves to the destination Q (step S8). Further, the position coordinate data of the designated point F ₃ stored in the memory immediately before and after this is replaced with the coordinate data of the moving destination Q. The image on the screen R after this processing is completed is shown in FIG. 8 (c), and is the same as the point Q in FIG. 8 (b).
F _new becomes a new pointing point, and a new position marker M _new corresponding to it is displayed at this position. Then, in the next step S9, the operator performs a key operation to restart the follow-up operation. When there are a plurality of pointing points to be corrected, step S9 is executed after finishing the correction for each pointing point.

In this way, the movement correction of the indicated point is completed,
Alternatively, when it is determined in step S5 that the position of each designated point F _i is appropriate, the processing of step S10 and thereafter is executed. However, when there is no need for correction as described above,
The key input to that effect moves to step S10.

In step S10 and thereafter, first, the microcomputer 21 captures the position of each designated point F _i (step S10),
Based on this, the teaching point position is calculated (step S1
1). Although the instruction point F _i itself may be adopted as this teaching point, a curve that smoothly connects each instruction point F _i (i = 1, 2, ...) Is obtained, and the point on the curve is set as the teaching point. By doing so, a further preferred teaching is given.

After that, the sensor head SH is moved to the position of this teaching point. This may be performed by, for example, giving movement information to the robot side such that the position of the teaching point matches a reference position (not shown) set on the screen R to control the movement of the robot. And the position of the robot in that state
Take in attitude data based on the outputs of encoders E _{1 to} E ₆ ,
It is used as teaching data (step S12).

These processes are repeated until the end of the marking line C (step S13), whereby the sensor head SH moves following the marking line C, and a series of teaching data fetching processes is executed.

In the above operation, since the position of the designated point F _i is once automatically set, it is not necessary to manually set each designated point F _i, and the high speed by automatic tracking is maintained. On the other hand, the inappropriate pointing point is corrected to an appropriate position based on visual inspection and manual input, so that the accuracy of tracking is remarkably improved. Therefore, by using the device of this embodiment, the efficiency of the tracking process can be greatly improved.

E. Modifications One embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and the following modifications are possible.

The work line is not limited to a scribe line, but may be a line in which fluorescent paint or the like is applied to the surface of the work W in a band shape and scribed. In this way, the ruled lines appear more clearly on the image, which is more suitable for automatic tracking. Alternatively, a work line drawn with a paint on the surface of the work W, or a tape to which a thin cutout line is provided on the tape may be used.

In the above embodiment, the visual judgment is used in combination throughout the teaching process. However, the visual judgment may be added only to a portion such as a corner portion where an indication point setting error is likely to occur. Alternatively, once the teaching is performed with the data that is still set automatically, a reproduction test may be performed to correct only the portion determined to be inappropriate.

Further, in the embodiment, the case where the designated point is set at the center of the working line is shown, but the designated point may be set at the edge of the working line or at a position deviated from the working line by a predetermined distance. That is, the present invention can be generally applied to the case where a position having a predetermined relationship with the image of the working line is adopted as the setting position of the pointing point.

In order to follow the work line, the relative spatial relationship between the sensor head and the work need only be changed, so the sensor head is fixed spatially and only the position / orientation on the work W side is changed. The present invention can also be applied to.

INDUSTRIAL APPLICABILITY The present invention is applicable not only to robot teaching but also to various machine tools that perform desired processing while following the marking lines.

(Effects of the Invention) As described above, according to the present invention, the setting of the pointing point itself is automatically performed, but it can be corrected visually, so that it is possible to automatically correct the image of the working line. Even if the set pointing point exists at an inappropriate position, the inappropriateness will be eliminated by the above-mentioned correction, and an appropriate work line tracking operation can be performed without losing the efficiency of automatic tracking. be able to.

[Brief description of drawings]

1 is a perspective view showing an outline of a mechanical structure of an embodiment in which the present invention is applied to teaching of an industrial robot, FIG. 2 is a schematic block diagram showing an electric structure of the robot of FIG. 1, FIG. 3 is a partial sectional view showing the detailed structure of the sensor head, FIG. 4 is a sectional view taken along the line AA ′ of FIG. 3, and FIGS. 5 and 6 are the principle of controlling the relative distance / posture between the sensor head and the workpiece. FIG. 7 is a flow chart showing the operation of the embodiment, FIG. 8 is an illustration of the operation of the embodiment, and FIGS. 9 to 11 are illustrations of a conventional work line tracking method. RB ... Laser cutting robot, 9 ... Control device, 10 ... Operation panel, 11 ... External computer, 22 ... Image processing device,
T ...... laser torch, SH ...... sensor head, W ...... workpiece, C ...... scribed line (tool line), L _a ~L _c ...... spotlight,
P _{1 to} P ₃ …… Light spot, L …… Illumination light, F _i …… Indicator point,
M _i …… Position marker

Claims (1)

(57) [Claims] 1. An image of a working line attached to the surface of a workpiece is read, and a pointing point for pointing the position of the working line is automatically set at a position having a predetermined relationship with the image of the working line. In a work line tracking device that gives operation information determined according to the position of the pointing point to a predetermined machine tool and causes the machine tool to follow the working line, the position of the automatically set pointing point is Display means for displaying together with the image of the working line, and pointing point movement correcting means for moving and correcting the pointing point to a desired position based on a manual input given according to the display content of the display means are provided. A work line tracking device.