JP3191563B2 - Automatic correction method for offline teaching data - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of automatically correcting offline teaching data of a robot.

[0002]

2. Description of the Related Art In a production line of an automobile body, a general-purpose robot equipped with a robot gun reproduces teaching data taught on a workpiece positioned on a pallet and sent by a conveyor, thereby providing a predetermined teaching data. Work is being carried out. In the following description, the case where the robot gun is a spot welding gun is taken as an example, but the robot gun is not limited to the spot welding gun, but may be a roll welding gun or a sealer application sealer gun. When the shape of a work (for example, a body) and a spot welding position are changed at the time of a model change of an automobile, it is necessary to teach the robot the teaching data corresponding to the change. After re-teaching, work of the same type is welded with the re-taught data until the next model change. Conventionally, teaching data to the robot has been
There are online teaching and offline teaching. In online teaching, a robot gun is moved to a position corresponding to a work hitting position by a robot at a site, and the point is taught to the robot by a teach pendant. This is performed for each hitting position. In offline teaching, teaching data is created in a personal computer between a virtual robot and a virtual work, not at the site, but offline, and input to the actual robot.

[0003]

However, there is a problem that on-line teaching requires skill and that teaching data is slightly different for each person. Also, in the conventional offline teaching, a difference occurs between the position taught off-line and the position of the robot actually installed due to the robot installation position shift and the bending of the robot arm due to the weight of the welding gun. You need to correct the data, and the correction is not accurate enough,
There is a problem that there is a variation depending on an operator, and a setup for correction is difficult. In particular, since the conventional correction of off-line teaching data includes a reference point teach, the correction accuracy may be insufficient depending on the hit point position. More specifically, a body is placed on a pallet and conveyed to the position of a welding robot by a conveyor, stopped, a point on the pallet or a robot (for example, a pin of the pallet) is selected as a reference point, and the position of the reference point is measured. By repeating this at least three times while changing the posture of the reference point, the actual position of the reference point is obtained, and the deviation between the actual position of the reference point and the theoretical position of the reference point taught in the offline teaching is obtained. Offline teaching data of all the hit points are corrected uniformly by the minute. However, when the robot gun moves to a different position from the reference point position at the time of performing the calibration in a different posture, the manner of application of the gun's own weight changes, and the position after correction also changes to the actual position. Since the position is slightly displaced, there may be portions where accuracy is insufficient depending on the hitting position.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an automatic correction method for off-line teaching data, which can correct the positional deviation with respect to all the hitting positions with high accuracy, and automatically performs the correction.

[0005]

The method of the present invention for achieving the above object is as follows. ( 1 ) A CCD camera is mounted on both the pair of robot gun mounting parts of the robot, and marks of the same size are provided on the front and back of each work hitting position, and the offline teaching data is reproduced by the robot for the work. At the time of reproduction, both CCDs
The two robot gun mounting parts are simultaneously moved by the same amount in the z direction of the tool coordinates of the robot so that the diameters of the images of the respective marks captured by the camera are the same as each other,
A method for automatically correcting the offline teaching data, wherein the offline teaching data is corrected by the moving amount. ( 2 ) An automatic correction method for offline teaching data using a robot in which the robot drives the robot gun electrode in the z direction in the robot tool coordinates with the servomotor, and the offline teaching data is processed by the robot. , And at the time of reproduction,
For each hit point position, one of the robot gun electrodes is driven in a direction approaching the work, and it is detected that the electrode has hit the work, and the z-direction position of the work in the robot tool coordinates is determined from the electrode movement amount up to that time. A method for automatically correcting off-line teaching data, wherein the off-line teaching data in the z direction of the one robot gun electrode is obtained from the work position. ( 3 ) A distance sensor is mounted on at least one of the pair of robot gun mounting parts of the robot, and the offline teaching data is reproduced for the work by the robot. The distance sensor is moved by driving the robot in a direction perpendicular to the longitudinal direction of the flange of the distance sensor, and the position where the distance data between the distance sensor and the flange suddenly changes is recognized as the edge of the work, and the hitting position of the offline teaching data and the position of the work are recognized. A method for automatically correcting off-line teaching data, wherein a distance to an edge is determined, and a hitting position of the off-line teaching data is corrected in a flange plane so that the distance becomes a predetermined distance. ( 4 ) A CCD camera is mounted on at least one of the pair of robot gun mounting parts of the robot, and cylindrical marks are provided at each of the hit points of the work, and the offline teaching data is reproduced on the work by the robot. At the time of reproduction, for each hit point position, the posture of the at least one robot gun mounting portion is changed so that the image of the mark recognized by the CCD camera becomes a perfect circle, and a vertical deviation is obtained. An automatic correction method for offline teaching data that corrects offline teaching data.

[0006]

In any of the above (1) to ( 4 ), for each of the hitting positions, the actual hitting position obtained by mechanically detecting the mark attached to the hitting position and the offline teaching data The position of the gun mounting part of the robot is moved so that the position of the robot coincides with the position of the robot, and the offline teaching data is corrected by the amount of movement. The displacement caused by the deflection of the robot arm and the displacement caused by the bending of the robot arm are corrected, and the accuracy becomes high. Also, the detection of the mark, the movement of the gun mounting portion of the robot to match the theoretical position with the actual position, the calculation of the amount of movement, and the correction of the offline teaching data are automatically performed, without variation among operators, It takes place in a short time.

[0007]

Embodiments of the present invention will be described below. In the figure,
FIGS. 1 to 3 and FIGS. 18 and 19 are applicable to any embodiment of the present invention, and FIGS. 4 to 6 and 20 are applied to the first embodiment of the present invention . 8 and 21 are applied to the second embodiment of the present invention, FIGS. 9 to 11 and 22 are applied to the third embodiment of the present invention, and FIGS. 12 to 17 and FIG. 4 is applied in an exemplary embodiment.

First, a common configuration applicable to all embodiments will be described. The common components are denoted by the same reference numerals throughout all embodiments. FIG. 1 shows an apparatus for performing the method of the present invention,
A spot gun welding device is shown as an example. 1 is
A work, for example, a car body. The work 1 is positioned and mounted on a pallet, flows on a conveyor line, and is stopped at the position of the robot 2. Robot 2
Is composed of a general-purpose robot having a six-degree-of-freedom tip, for example, an articulated robot having six axes. A robot gun 3 is attached to the tip of the robot 2, and a desired operation is performed on the work 1. When the robot gun 3 is the spot welding gun 3, the spot welding is performed on the work 1
Done for Robot guns are not limited to spot welding guns. For example, as shown in FIG. 2, when the robot gun is a sealer gun 3B, a sealant is applied to the work 1. As shown in FIG. 3, when the robot gun is a roll welding gun 3C, roll spot welding is performed on the workpiece 1. These are included in the present invention.

The movement of the tip (robot gun mounting portion) of the robot 1 is controlled by a robot control panel 4 electrically connected to the robot 1. Robot control panel 4
The offline teaching data is input before the offline teaching data correction, and when the type of the work 1 is changed due to a model change or the like, the first one of the changed work 1 is flowed on the conveyor and the robot is moved at the robot position. It is stopped, and the offline teaching data is automatically corrected using the method of the present invention online using the first single work 1. 2 which is run on the conveyor
Operations such as spot welding are performed on the workpieces 1 of the same type subsequent to the table using the corrected data.

In the robot gun mounting portion of the robot 1,
Actual hitting point detecting means 5, for example, CCD camera 5
A is attached by removing at least one robot gun. The data detected by the detection means 5 is sent to an image processing device 6 provided at the position of the robot control panel 4, and the processed data processed there is input to the robot control panel 4. The offline teaching data is automatically corrected by the robot control panel 4. FIG. 18 shows a difference in logic between the conventional offline teaching data correction and the offline teaching data correction of the present invention. In step 101, teaching data (strike position, motion trajectory, welding conditions) is created off-line based on the virtual robot and the virtual work in the computer, and in step 102, the robot 2 installed on the site Enter the offline teaching data in Step 10
Up to 2, the conventional and the present invention are the same. In the present invention, the work 1 is set in step 103, the marking 8 is applied to the hitting position of the work, and the work is sent to the robot position and stopped. Next, in step 104, the offline teaching data is reproduced for the target work 1 by the robot 2. Since the actual position is different from the position where the offline teaching data was reproduced, step 1
At 05, the actual position of the mark is obtained by using the detecting means 5. For example, when the detecting means is the CCD camera 5A, the mark 8 is photographed, and the image is processed by the image processing device 6 to obtain the actual position. Then, the robot is moved so that the online data and the offline data coincide with each other, and the movement amount is regarded as the deviation amount, and the offline teaching data is automatically corrected in the robot operation panel 4 by the deviation amount between the offline teaching data and the actual data. This is executed for each of all the hit points. Detection is performed by detecting means C
In the case of a CD camera, for example, moving a scanning point along a horizontal scanning line within a screen is repeated in the vertical direction, and when a scanning point comes to a mark position is detected from a change in color or brightness of the screen, and a mark of the mark is detected. This is performed by recognizing the shape and finding the mark center point.

[0011] In the above offline teaching data,
The correction for the shift amount will be described with reference to FIG . The coordinates (values known from the encoders of each axis) in the robot coordinate system 打_R of the reference point (each hit point position) on the workpiece measured online with a CCD camera or the like are represented by P _iR = (X _iR ,
Y _iR , Z _iR ) ^T. Here, () ^T represents a transposed matrix. The coordinates in the absolute space coordinate system Σ ′ _R of the same reference point, which were taught off-line, are represented by P ′ _iR = (X
_{'IR, Y'iR,} and _Z'iR) ^T. The difference between the data expressed in the Σ ′ _R coordinate system and the off-line teaching data using the matrix T that converts P _iR into the absolute space coordinate system is the shift amount.

[0012]

(Equation 1)

With respect to T, this is represented by a minute translation {x, △
y, and △ z, rotation [delta] _x, [delta] _y, and the matrix of △ T for the [delta] _z. However, the relational expression between ΔT and its element is known, and is given by the following expression.

[0014]

(Equation 2)

The difference between the off-line data and the on-line data after the correction is 0 as expressed by the following equation.

[0016]

[Equation 3]

In the above equation, the T matrix is a matrix specific to the robot and known. ΔT is a matrix given from the movement amount of the robot mounting unit. Therefore, the correction time is, P'by _iR is given, P _iR is determined. Thereby, the off-line data _P'iR, online data P _iR is automatically determined by the robot control board (computer). That is, the offline teaching data is automatically corrected.

Next, a configuration specific to each embodiment of the present invention will be described. In the first embodiment of the present invention, FIGS.
As shown in FIG. 20 , the CCD cameras 5B are mounted on both the pair of robot gun mounting portions of the robot 2, and marks 8 of the same size are provided on the front and back of each of the hit points of the work 1. The mark 8 is desirably circular in shape and is attached to the work 1. Next, Robot 2
Then, the offline teaching data is reproduced for the work 1. At the time of reproduction, both CCDs
Both CCD cameras 5B are set so that the diameters of the images of the respective marks 8 captured by the cameras 5B are equal to each other.
Are simultaneously moved in the z direction of the tool coordinates of the robot 2 (a direction orthogonal to the surface of the work at the hitting position), and the offline teaching data is corrected by the amount of movement (Δz). This correction is made automatically in the robot control panel. FIG. 20 shows a flowchart of the first embodiment of the present invention. In step 201, the offline teaching data is reproduced by the robot, and in step 20
In step 2, the diameter D1 of the mark recognized by the one CCD camera 5B is calculated. Next, in step 203, the data of D1 is fed back in the robot control panel, and in step 204, one CCD is referred to based on the data of D1.
The z-direction distance L1 between the camera 5B and the hit point position is calculated.
In step 205, the diameter D2 of the mark recognized by the other CCD camera 5B is calculated. Next, in step 203, the data of D2 is fed back in the robot control panel, and in step 204, the distance L2 in the z direction between the other CCD camera 5B and the hit point is calculated based on the data of D2. Next, at step 208, L1
It is determined whether or not L2 and L2 are equal, and the robot posture is corrected in step 209 until it becomes equal. Step 208
If it is determined that L1 and L2 are equal in step 210, step 210
The data is converted into final data, and it is checked in step 211 whether or not all the hit points have been completed. If the process has not been completed for all the hit points, the above cycle is repeated, returning to step 201.

In the second embodiment of the present invention, as shown in FIGS. 7, 8 and 21 , the servo gun 5C drives the robot gun electrode 11 in the z direction in the robot tool coordinates with respect to the robot. This is a method for automatically correcting offline teaching data using a robot that has been used. The offline teaching data is reproduced for the work 1 by the robot. At the time of reproduction, one of the robot gun electrodes 11 is driven in a direction approaching the work 1 for each of the hit points, and it is detected that the electrode 11 has hit the work 1, and the robot tool of the work 1 is determined from the electrode movement amount up to that time. The position in the z direction in coordinates is obtained, the robot gun mounting unit is moved so that the electrode position is located at a predetermined position from the work, and the offline teaching data is corrected by the movement amount (Δz). The detection that the electrode 11 has hit the work 1 is performed by detecting that the feedback current from the servo motor 5C has increased, or by detecting that the data of the encoder 5D has not changed, or by detecting the pressure sensor 5E in the electrode.
(Transducer) is embedded and the pressure sensor 5
This is performed by detecting that the output value of E has suddenly changed.
FIG. 21 shows a flowchart of the second embodiment of the present invention. In step 301, the offline teaching data is reproduced by the robot. Then, step 302
Then, one electrode, for example, the upper electrode is brought closer to the work, and when the upper electrode comes into contact with the work in step 303, the contact is detected from the change in the servo current in step 304 and repeated until the change is detected. . Next, from step 305, the position of the upper electrode at the time of contact is detected by the encoder, and in step 306, the position information is fed back to the controller. Then step 3
At 07, the relative distance L between the chip and the work is calculated. Next, in step 308, it is determined whether or not L = (mt) / 2 (where m is the distance between the upper and lower chips, and t is the work plate thickness). If NO, the process proceeds to step 309 to correct the offline data. Then, in step 310, the robot position is corrected. If L = (mt) / 2 in step 308, the flow advances to step 311 to convert the corrected off-line data into final data. In step 312, it is confirmed whether or not all the hitting positions have been completed. Exit if you can confirm. If the process has not been completed for all the hit positions, the process returns to step 301 and the above cycle is repeated.

In the present invention,3In the example,9 and 10,
FIG.andFIG.As shown in FIG.
At least one of the robot gun mounting parts has a distance sensor
Attach 5F. Next, the robot 2
The teaching data is reproduced for the work 1. At the time of reproduction
For each of the hit points, the work where the hit point is located
What is the flange surface in the direction perpendicular to the longitudinal direction of the 1 flange
The distance sensor 5F is moved in parallel, and the distance sensor 5F
The position where the distance data from the flange changes suddenly
And the position of the offline teaching data
Find the distance from the edge of the work, and set the distance to a predetermined distance.
Move the robot gun mounting section to
Correct teaching data in the direction parallel to the flange surface
You. Thereby, the hit position after data correction, that is,
The actual hitting point position is set at a predetermined distance from the flange edge of the work 1.
It can be a remote location. If hitting position
Is shifted in the flange width direction and the welding position is near the flange edge.
Excessive dropping may cause welding burrs and reduce welding quality.
However, this is prevented in the present invention.FIG.
Is the first of the present invention34 shows a flowchart of the embodiment.
You. In step 401, the offline teaching data
Is reproduced by a robot. Then go to step 402
Then, the distance sensor 5F is run for each hit point position,
Feed sensor data to controller at step 403
Back. Then, in step 404, the sensor data
Judge whether or not has changed.
repeat. In step 404, the sensor data changes.
When it is confirmed that the running speed has been
Correct teaching data based on degree and running time
You. Next, at step 406, the position of the
It is determined whether it is a predetermined distance from the end of
To step 407, and the hit point position is a predetermined distance from the end of the flange.
Correct so that they are separated. At step 406,
When it is determined that the position is at a predetermined distance from the end of the flange,
Proceed to step 408 to finalize the modified offline data
Converted to data, and in step 409,
Check if has been completed, and if done, end.
If you have not finished all the points,
The above cycle is repeated in place of step 401.

In the fourth embodiment of the present invention, FIGS .
As shown in FIG. 7 and FIG. 23 , the CCD camera 5
G is mounted, and a cylindrical mark 8 is provided at each of the hitting positions of the work. Mark 8, a transparent cylindrical body, as shown in FIGS. 13 and 14, are made different colors of the upper surface and lower surface. Next, the robot 2 reproduces the offline teaching data for the work 1. At the time of reproduction, as shown in FIG. 17 , the posture of the CCD camera 5G is changed from the state of FIG . 15 to the state of FIG. 16 so that the image of the mark 8 recognized by the CCD camera 5G becomes a perfect circle at each hit point position . And the off-line teaching data is corrected by the moving amount of the vertical deviation. FIG.
Shows a flowchart of the fourth embodiment of the present invention. In step 501, the offline teaching data is reproduced by the robot. Next, in step 502, the image is fed back to the controller. Next, in step 503, it is determined whether or not the mark has been recognized as a perfect circle, and the posture of the robot is corrected in step 504 until the mark is recognized as a perfect circle. Step 50
In step 3, if the mark can be recognized as a perfect circle, step 5
Go to step 05, correct the offline data, convert the corrected offline data to final data,
At 06, it is confirmed whether or not all the hitting positions have been completed. If the process has not been completed for all the hit points, the above cycle is repeated, returning to step 501.

Next, the operation will be described. The offline teaching data is automatically corrected on site and converted to final teaching data by the method of the present invention. This data correction is performed for each hit point position, and
This is done automatically in the control panel. As a result, the accuracy of the offline teaching data may be rough because the corrected data has high accuracy. Further, since the correction is automated, the working time is reduced as compared with the conventional online teaching. In addition, the automation eliminates a part that is influenced by human sensitivity, thereby improving the quality of correction and the quality of work.

[0023]

According to any of the embodiments of the present invention, the offline teaching data can be corrected on-site with high accuracy, and the correction can be automatically performed.

[Brief description of the drawings]

FIG. 1 is a perspective view of an apparatus embodying the present invention.

FIG. 2 is a perspective view of a portion of a robot gun of another example device embodying the present invention.

FIG. 3 is a perspective view of a portion of a robot gun of still another example of an apparatus embodying the present invention.

FIG. 4 is a perspective view of a CCD camera mounting portion of the apparatus according to the first embodiment of the present invention.

5 is an enlarged side view of the CCD camera mounting portion of the apparatus of FIG.

FIG. 6 is a front view of a CCD camera shooting screen of the apparatus of FIG . 4 ;

FIG. 7 is a perspective view of a mounting portion of a hit point position detecting means according to a second embodiment of the present invention.

8 is an enlarged side view of a mounting portion of another hit point position detecting means of the apparatus of FIG . 7 ;

FIG. 9 is a perspective view of a CCD camera mounting portion of the device according to the third embodiment of the present invention.

10 is an enlarged plan view of a workpiece portion of the device of FIG.

FIG. 11 is a detection data diagram of the apparatus of FIG . 9 ;

FIG. 12 is a perspective view of a CCD camera mounting portion of the device according to the fourth embodiment of the present invention.

13 is a perspective view of the mark of the device of FIG.

FIG. 14 is a perspective view of another mark of the apparatus of FIG . 12 ;

15 is a side view of a CCD camera mounting portion of the apparatus of FIG. 12.

FIG. 16 is a side view of the device of FIG . 12 after a posture of a CCD camera mounting portion is corrected.

FIG. 17 is a front view of a photographing screen of a CCD camera of the apparatus of FIG . 12 ;

FIG. 18 is a flowchart of automatic correction control according to the present invention.

FIG. 19 is a perspective view of the logic of automatic correction control that can be used in the present invention.

FIG. 20 is a flowchart of correction control according to the first embodiment of the present invention.

FIG. 21 is a flowchart of correction control according to the second embodiment of the present invention.

FIG. 22 is a flowchart of correction control according to the third embodiment of the present invention.

FIG. 23 is a flowchart of a correction control according to a fourth embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 work 2 robot 3 operation gun 4 robot control panel 5A, 5B, 5G CCD camera 5C servo motor 5D encoder 5E pressure sensor 5F distance sensor 7 robot gun 8 mark 10 center of screen

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-8185 (JP, A) JP-A-3-166086 (JP, A) JP-A-7-84631 (JP, A) JP-A-7-846 121214 (JP, A) Japanese Utility Model Hei 6-65902 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G05B 19/18-19/46 B23K 11/10-11/36 B25J 3/00-3/10 B25J 9/10-9/22 B25J 13/00-13/08 B25J 19/02-19/06

Claims (4)

(57) [Claims] 1. A CCD camera is mounted on both of a pair of robot gun mounting portions of a robot, and marks of the same size are provided on each of front and back of a work hitting position, and the robot outputs offline teaching data to the work. At the time of the reproduction, the two robot gun mounting parts are simultaneously moved to the tool coordinate z of the robot so that the diameter of the image of each of the marks captured by both CCD cameras is the same for each of the hit positions. Moving the same amount in the same direction, and correcting the offline teaching data by the amount of movement. 2. A method of automatically correcting off-line teaching data using a robot in which a robot motor drives a robot gun electrode in a z-direction in a robot tool coordinate system by a servo motor. Is reproduced for the work, and at the time of reproduction, for each hit point position, one of the robot gun electrodes is driven in the direction approaching the work, and it is detected that the electrode has hit the work, and the electrode movement amount up to that time is detected. A method for automatically correcting off-line teaching data, comprising: obtaining a z-direction position of a work in robot tool coordinates; and correcting the z-direction offline teaching data of the one robot gun electrode from the work position. 3. A distance sensor is mounted on at least one of a pair of robot gun mounting parts of the robot, and the offline teaching data is reproduced for the work by the robot. The distance sensor is moved by driving the robot in the direction orthogonal to the longitudinal direction of the flange of the workpiece to be moved, and the position where the distance data with the flange of the distance sensor suddenly changes is recognized as the edge of the workpiece, and the hitting position of the offline teaching data is recognized. And determining the distance between the off-line teaching data and the edge of the workpiece, and correcting the hitting position of the off-line teaching data in the flange surface so that the distance becomes a predetermined distance. 4. A CCD camera is mounted on at least one of a pair of robot gun mounting parts of the robot,
A cylindrical mark is provided at each of the work dot positions, and the offline teaching data is reproduced for the work by a robot.
Determining the vertical deviation by changing the posture of the at least one robot gun mounting part so that the image of the mark recognized by the camera becomes a perfect circle, and correcting the offline teaching data by the vertical deviation. Characteristic automatic correction method for offline teaching data.