JPS62148088A - Seam detecting device - Google Patents

Abstract

PURPOSE:To improve the efficiency in welding work by providing the means to offset the seam detecting signal and the like detected from the output of a seam detecting head. CONSTITUTION:A seam detecting head 11 is fitted to the bracket of a welding robot and connecting as well to a sensing start position arrival detecting circuit 13 and in-outputs interface circuit 15 via switching circuit 12. Moreover, a comparator 16 is provided on the detecting circuit 13 and the output of the seam detecting head 11 is fed to the terminal of one part and an offset setting circuit 17 is connected to the input terminal of the other part as well. A seam detection processing unit 14 outputs a seam detection signal by the abrupt output variation of the seam detecting head 11 and a detection signal delay circuit 18 offsets the seam detection signal according to the offset set value. In this way, the robot work can be changed without the teaching correction. Consequently the efficiency in welding work is improved.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a seam detection device.

(Prior Art) For example, in a car body assembly process, joint lines of workpieces are automatically welded by a robot.

In this way, when the robot welds the seam line of the workpiece, it is necessary to teach the robot the working position where the welding torch follows the seam line.

Therefore, in the past, a seam detection head was attached to the bracket that holds the robot's welding torch, and the robot detected the seam detection head at multiple locations on the workpiece having seam lines, in the X direction intersecting the workpiece, and in the X direction perpendicular to the X direction. In addition, the seam is sensed by moving in the Y direction that intersects the seam line, and welding is performed based on the X and Y coordinate positions of the seam detected in each sensing and data representing the relative positions of the seam detection head and welding torch. The torch teaches the working position of the robot that follows the seam line.

FIG. 7 shows the circuit configuration of the main parts of the seam detection device in this case. The seam detection head 1 is made up of, for example, a laser sensor having a laser light source and a light receiving element that receives the laser light emitted from the laser light source and reflected by the workpiece, and its output is sent via a switching circuit 2 to a sensing start position arrival detection circuit 3. and is supplied to the seam detection processing circuit 4. The switching circuit 2 is controlled by a robot controller (not shown) via a human output interface circuit 5, and is turned on by a sensing start signal from the robot controller and turned off by a sensing end signal. The sensing start position arrival detection circuit 3 has a comparator 6, which compares the output of the seam detection head 1 with a reference value S corresponding to a predetermined desired X coordinate position, and
When the output reaches the reference value S, a sensing start position arrival signal is output to the robot controller via the input/output interface circuit 5.

Further, the seam detection processing circuit 4 detects a sudden change in the output of the seam detection head 1, and at that point outputs a seam detection signal to the robot controller via the human output interface circuit 5.

In detecting the X and Y coordinate position of a seam using this seam detection device, in each sensing step, the switching circuit 2 is first turned on by a sensing start signal, and the seam detection head 1 is moved in the X direction intersecting the workpiece. Thereafter, when a sensing start position arrival signal is generated from the sensing start position arrival detection circuit 3, the robot is positioned at that position. Next, at that X coordinate position, move the seam detection head 1 in the Y direction that is perpendicular to the X direction and intersects with the seam line of the workpiece, and at the point when the seam detection signal is generated from the seam detection processing circuit 4. The X, Y coordinate position of the robot is detected as the X, Y coordinate position of the seam.

(Problem to be Solved by the Invention) However, in such a conventional seam detection device, when the output of the seam detection head 1 reaches the reference value S, the seam detection signal is output from the successor seam detection processing circuit 4. Since the robot's X and Y coordinate positions at the time when If there is a slight change depending on the welding conditions, or if the positional relationship between the seam detection head 1 and the welding torch is slightly deviated due to an impact, etc., it is necessary to correct the teaching each time, which is a time-consuming problem. be.

The present invention was made by focusing on such conventional problems, and provides a seam detection device configured to arbitrarily change the relationship between the seam detection position and the working position of the robot without performing teaching correction. The purpose is to provide.

(Means and operations for solving the problem) In order to achieve the above object, the present invention processes the output from the seam detection head and detects a predetermined position arrival signal for the work of the seam detection head and/or Means for offsetting the seam detection signal is provided, thereby offsetting the seam detection position to a desired position.

(Example) FIG. 1 is a diagram showing an embodiment of the present invention.

In this embodiment, the seam detection head 11 is attached to the bracket of the robot, and the robot moves the seam detection head 11 in the X direction intersecting the workpiece having a seam line, and in the Y direction perpendicular to this X direction and intersecting the seam line. sense the seam by moving it in the direction.

The joint detection head 11 is comprised of a differential transformer type contact sensor that outputs, for example, a stroke change as an electric signal, and its output is supplied to a sensing start position arrival detection circuit 13 and a joint detection processing circuit 14 via a switching circuit 12. The switching circuit 12 is connected to an input/output interface circuit 15 by a robot controller (not shown).
It is turned on by the sensing start signal and turned off by the sensing end signal. The sensing start position arrival detection circuit 13 is provided with a comparator 16, one input terminal of which is supplied with the output of the seam detection head 11, and the other input terminal of which is supplied with an offset value from an offset value setting circuit 17. When the output of the joint detection radar 11 reaches the offset value, a sensing start position arrival signal is supplied to the robot controller via the human output interface circuit 15. Here, the offset value supplied from the offset value setting circuit 17 to the comparator 16 can be arbitrarily set within the range of ±α with respect to the reference value S.

Further, the seam detection processing circuit 14 detects a sudden change in the output of the seam detection head 11 and outputs a seam detection signal, and the seam detection signal is set by the offset value setting circuit 17 in the detection signal delay circuit 18. The signal is delayed in accordance with the offset value of the delay time and is supplied to the robot controller via the human output interface circuit 15.

Here, the offset value of the delay time in the detection signal delay circuit 18 by the offset value setting circuit 17 can be arbitrarily set in the range of 0 to +β.

FIG. 2 shows the configuration of the tip of the robot arm that holds the welding torch and seam detection head. A bracket 22 is attached to the tip of the robot arm 21, and a welding torch 23 and a joint detecting rod 11 are attached to the bracket 22. The welding torch 23 is held by fixing its power cable 24 to the bracket 22,
A welding wire supply nozzle 26 is fixed to the bracket 22 by a nozzle fixing guide 25 at the tip. Also,
The joint detection head 11 is attached to a holding member 27, and the holding member 27 is fixed to a rotating shaft 29 of a rotary air cylinder 28 attached to a bracket 22. In this way, by selectively operating the rotary air cylinder 28, the seam detection head 11 is rotated 90 degrees and positioned at the sensing position shown by the solid line and the retreat position during welding work shown by the imaginary line. do. Note that the lead wire 11a of the joint detection lead 11 is connected to a connector 30 provided on the holding member 27.
Connect to the seam detection device via.

The operation of this embodiment will be explained below.

First, in response to a sensing start signal, the seam detection head 11
is positioned at the sensing position shown by the solid line in FIG. 2, the switching circuit 12 is turned on in FIG. 1, and the seam detection head 11 is moved by the robot to the robot origin P as shown in FIG. 3.

Move from (0, 0) in the X direction intersecting the workpiece 35, and stop the movement in the X direction when the sensing start position arrival signal is supplied from the sensing start position arrival detection circuit 13 to the robot controller. . Here, in the offset value S±α supplied from the offset value setting circuit 17 to the sensing start position arrival detection circuit 13, the X coordinate position corresponding to the reference value S is X, and the X coordinate position corresponding to the change value ±α is Assuming that xo, the robot coordinate position at the dwarf sensing start position P+' shown in FIG. 3 is X±X,,0).

Next, the sensing start position P+' (x:!:y
a, 0), the seam detection head 11 is perpendicular to the X direction,
and move it in the Y direction that intersects the seam line of the workpiece 35,
X of the robot at the time when the joint detection signal is supplied from the detection signal delay circuit 18 to the robot controller.

The Y coordinate position is detected as the X and Y coordinate position of the seam 36. Here, the Y coordinate position at the time when the seam detection signal is output from the seam detection processing circuit 14 is y, and it corresponds to the offset 1-direction β of the delay time in the detection signal delay circuit 18 set by the offset 1-direction setting circuit 17. Assuming that the Y coordinate position is yβ, the coordinate position of the seam 36 is detected as P2' (X+Y+yβ) as shown in FIG. In addition, in Fig. 3, Po, P, ' and P
A solid line connecting Po.2' indicates the locus of the seam detection head 11 in this embodiment.

The broken line connecting Pl and P2 supplies the reference value S to the sensing start position arrival detection circuit 13, and also indicates the direction 11 for seam detection when the seam detection signal from the seam detection processing circuit 14 is supplied to the robot controller without delay. , P I (x, O) and P2 (x, y)
respectively indicate the robot coordinate position at the time when the sensing start position arrival signal and the seam detection signal in this case are supplied to the robot controller.

In this way, according to this embodiment, the seam detection position is set to (±x
, , +yβ), the relationship between the seam detection position and the robot's working position is within the range of (±, +yβ).
If the change is within the range of yβ), the effort of teaching correction can be saved.

FIG. 4 is a diagram showing another embodiment of the present invention.

In this embodiment, a sensing number receiving circuit 4I is provided, and an offset value setting circuit 42 is configured to set and retrieve an offset 1 S±αl in the X direction and an offset value βl in the Y direction corresponding to the sensing number l. This embodiment basically differs from the embodiment shown in FIG. 1 in that this embodiment is made similar to the embodiment shown in FIG. 1, and the other configurations are the same as those in FIG.

In this embodiment, the sensing number receiving circuit 41 receives the sensing number 1 from the robot controller, turns on the switching circuit 12, and supplies the received sensing number 1 to the offset value setting circuit 42. The offset value setting circuit 42 searches for an offset value S±α1 in the X direction and an offset value +β1 in the Y direction according to the supplied sensing number j, and sends these searched offset values to the sensing start position arrival detection circuit 13 and The detection signal is supplied to the delay circuit 18.

FIG. 5 schematically shows the configuration of an offset value setting circuit 42 for setting and searching offset values S±αl and β1. Offset change value corresponding to sensing number 1 ±α1. β1 is inputted in advance and stored in the storage medium 43, and from these set changed values, the changed values ±α1 . The search circuit 44 searches for β1. Among the searched change values, the change value ±α1 in the X direction is added to the reference value S in the adder 45, and the output S±αl
is supplied to the sensing start position arrival detection circuit 13 as an offset value in the X direction, and the change value βl in the Y direction is supplied as it is to the detection signal delay circuit 18 as an offset value for the delay time in the detection signal delay circuit 18.

FIG. 6 is a flow chart showing the operation of this embodiment. In the robot controller, first, in step 1, sensing number 1 is sent to the seam detection device, and in step 2, a search in the X direction is started to move the seam detection head 11 in the X direction. In addition, in the seam detection device, first, in step 3, based on the sensing number 1 from the robot controller, the offset value setting circuit 42 searches for offset values S±αl, βl in the X and Y directions corresponding to the sensing number 1, Then X
After the direction search starts, data from the seam detection head 11 is taken in step 4, and the data is compared with the offset value S±α1 in the X direction in step 5 by the sensing start position arrival detection circuit 13 to reach the sensing start position. decide whether or not.

In step 5, when the output data of the seam detection radar 11 and the offset value S±αl match, in step 6 a sensing start position arrival signal is sent to the robot controller via the output interface circuit 46. In step 7, the robot controller determines whether or not there is a sensing start position arrival signal from the seam detection device, and when the signal is supplied, ends the search in the X direction,
Next, in step 8, a search in the Y direction is started in which the seam detection head 11 is moved in the Y direction.

After starting the search in the Y direction, in the seam detection device, in step 9, the seam detection processing circuit 14 determines whether or not a seam has been detected.If a seam is detected, then in step 10, the seam detection signal is sent to the seam detection processing circuit 14. After the detection signal delay circuit 18 delays the Y-direction offset value β1 retrieved in step 3 corresponding to the sensing number 1, the seam detection signal is supplied to the robot controller via the output interface 1146 in step 11.

Thereby, the operation of the seam detection device for the sensing number 1 ends.

In the robot controller, the presence or absence of a seam detection signal from the seam detection device is determined in step 12, and when the signal is supplied, the current position of the robot is stored as the seam position at the sensing number l in step 13, and this Thus, the operation at the sensing number l is ended.

In this way, in each sensing, the sensing start, start position arrival signal and seam detection signal output from the sensing start position arrival detection circuit 13 and from the seam detection processing circuit 14 through the detection signal delay circuit 18 are output to the output interface. The signal is supplied to the robot controller via a circuit 46 to detect the joint position.

According to this embodiment, the offset value for each sensing can be set in the offset value setting circuit 42, and the set offset value can be automatically searched for each sensing, so that the seam line can be detected efficiently and quickly. be able to.

Note that this invention is not limited only to the embodiments described above, and numerous modifications and changes are possible. For example, the seam detection head 11 is not limited to a differential transformer type contact sensor, but can also use other contact sensors such as a linear potentiometer, a rotary potentiometer that converts linear motion into rotational motion, a rotary encoder, etc., or a laser A non-contact sensor such as a sensor or an eddy current distance measuring sensor can also be used. Furthermore, in each of the embodiments described above, the offset is made in both the X direction and the Y direction, but it is also possible to offset only one of them. Furthermore, the offset value in the Y direction can be set not only in the positive direction but also in the negative direction. In this way, when setting in the negative direction, the Y[! of Robo Soto at the time the seam detection signal is output from the seam detection processing circuit 14. The Y coordinate position of the seam can be obtained by subtracting the set offset value from the target position.

(Effects of the Invention) As described above, according to the present invention, it is possible to offset the predetermined position arrival signal and/or seam detection signal for the workpiece detected by the seam detection head by processing the output from the seam detection head. Therefore, the relationship between the seam detection signal and the robot's working position can be changed arbitrarily without performing teaching corrections. therefore,
For example, a welding robot can easily perform welding work according to the workpiece and welding conditions.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of the tip of a robot arm that holds a welding torch and a seam detection head, and FIG. 3 is an operation of the embodiment shown in FIG. 1. FIG. 4 is a diagram showing another embodiment of the present invention, and FIG. 5 is a diagram for explaining the fourth embodiment.
FIG. 6 is a flowchart for explaining the operation of the embodiment shown in FIG. 4, and FIG. 7 is a diagram showing a conventional technique. 11... Seam detection head 12... Switching circuit 13... Sensing start position arrival detection circuit 14...
Seam detection processing circuit 15...Input/output interface circuit 16...Comparator 17...Offset value setting circuit 18...Detection signal delay circuit 21...Robot arm 22...Bracket 2
3...Welding torch 24...Power cable 2
5... Nozzle fixing guide 26... Welding wire supply nozzle 27... Holding member 28... Rotary air cylinder 29... Rotating shaft 30... Connector 3
5... Workpiece 36... Seam 41... Sensing number receiving circuit 42... Offset value setting circuit 43... Storage medium 44... Search circuit 45.
...Adder 46...Output interface circuit Fig. 1 (sea, +βj Fig. 3 Fig. 4

Claims (1)

[Claims] 1. A seam detection head, which is installed so that it can approach and separate from a workpiece having a seam line, approaches a predetermined position on the workpiece and then moves it in a direction approximately perpendicular to the seam line of the workpiece to detect the seam. A seam detection device characterized in that the seam detection device is provided with means for offsetting a predetermined position arrival signal and/or a seam detection signal for a workpiece detected by the seam detection head by processing the output from the seam detection head. Device.