JP2007122705A - Welding teaching point correction system and calibration method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and accurately correct a teaching program without a worker's preliminary manual correction. <P>SOLUTION: The welding teaching point correction system 1 includes a robot 2; a spot welding gun 3 comprising two welding tips 31 and 32 provided to be opposed to each other; an imaging apparatus 4 to image a welding point of a workpiece by the welding tip 32, the imaging apparatus being provided detachably to or exchangeably with at least one 31 of the two welding tips so that the its optical axis is concentric with the axis of the welding tip 32; an operation control means 5 to control operation of the robot 2 and the spot welding gun 3; an image processing means 6 to acquire positional information of the welding point of the workpiece in the image by performing image processing of an image taken by the imaging device 4; and a program correction means 5 to correct a teaching point for the robot 2 in the teaching program 53a in a plurality of directions based on the positional information of the welding point of the workpiece in the image. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a welding teaching position correction system and a calibration method.

In processes where many spot welding robots are used, such as spot welding lines for automobile bodies, there is a method to create robot operation programs in advance for the purpose of reducing work man-hours and shortening work time when starting up equipment. It has been adopted. The spot welding robot operation program can be created in advance before installing the equipment. The mechanism and shape of the robot and spot welding gun, the shape of the workpiece (workpiece to be welded), the relative positional relationship between the robot and the workpiece, and the required welding operation conditions. An off-line teaching system that simulates robot operation on a computer and creates a program on the basis of information on the like is used.
However, when the program created by the offline teaching system is used after uploading to the actual robot after installation, installation errors of the robot and jig, machine differences between robots, workpiece dimensional errors, and deflection due to gravity For example, the welding position may deviate from the intended position. For this reason, before performing automatic operation for all or some of the welding points, it was necessary for the operator to manually operate the robot, check the operation position, and correct offline teaching data as necessary. .

In order to solve such a problem, a method for correcting the axial direction of the welding tip in the off-line teaching data relating to the spot welding spot position is disclosed (for example, see Patent Document 1).
In addition, a method for correcting the straight displacement of the welding tip with respect to the work surface in the offline teaching data relating to the spot welding spot position is disclosed (for example, see Patent Document 2).
Japanese Patent No. 3191563 JP 2005-138223 A

However, according to the invention described in Patent Document 1, there is a problem that only one-way component data can be corrected among the offline teaching data. In addition, in the correction method described in Patent Document 1, it is necessary to place marks on both the front and back surfaces of the work spot position, and to install two cameras for imaging each mark. There was a problem that it was complicated and time-consuming.
Further, according to the invention described in Patent Document 2, the camera position is installed at a different location with respect to the tip of the spot welding gun, that is, the axis of the welding tip and the optical axis of the camera do not match. Therefore, there is a problem that it is necessary to teach the robot operation for recognizing the workpiece with the camera, which is troublesome. When taking the posture recognized by the camera, the spot welding gun mounted on the robot body or robot may interfere with surrounding workpieces or jigs, and measures must be taken to avoid this, There was a problem that it was very time-consuming. There is a problem that it is necessary to calibrate the camera in advance, which is troublesome, and an error caused by the accuracy of the calibration of the camera is likely to occur.

  Accordingly, the present invention has been made to solve the above-described problems, and the offline operation of the spot teaching robot offline teaching program is offline easily and accurately without manual correction by the operator in advance. It is an object of the present invention to provide a welding teaching position correction system and a calibration method capable of correcting a teaching program.

  According to a first aspect of the present invention, there is provided a welding teaching position correcting system, wherein a robot having a plurality of joints, a spot welding gun having two welding tips provided at the tip of the robot and arranged to face each other, and An imaging device that is detachably attached to the welding tip or replaceable with at least one of the welding tips, and is provided so that an optical axis is coaxial with the axis of the welding tip, and images a hitting point portion of the workpiece by the welding tip; Performing an image processing of the captured image captured by the imaging device, operation control means for controlling the operation of the robot and the spot welding gun in accordance with a teaching program for teaching the robot and the spot welding gun a welding operation, Image processing for acquiring position information of a hitting point portion of the workpiece by the welding tip in the captured image. And a program for correcting the teaching position of the robot in the teaching program in a plurality of directions based on position information of a hitting point portion of the work in the captured image acquired by image processing of the captured image by the image processing means And a correcting means.

  According to a second aspect of the present invention, in the welding teaching position correcting system, a spot welding gun having two welding tips fixed to each other and opposed to each other, a plurality of joints, and gripping a workpiece at the tip And a robot for supplying a workpiece to the spot welding gun, a detachable or at least replaceable welding tip on at least one welding tip, and an optical axis connected to the axis of the welding tip. The robot and the spot welding gun are controlled in accordance with an imaging device that is provided so as to be coaxial, and that images a spot of a workpiece by the welding tip, and a teaching program that teaches the robot and the spot welding gun a welding operation. An operation control unit for performing the image processing of the captured image captured by the imaging device, and the captured image Image processing means for acquiring the position information of the hit point portion of the workpiece by the welding tip, and based on the position information of the hit point portion of the work in the captured image acquired by the image processing of the captured image by the image processing means, Program correction means for correcting the teaching position of the robot in the teaching program in a plurality of directions.

The invention described in claim 3 is the welding teaching position correction system according to claim 1 or 2, further comprising storage means for storing a preset optimum spot position in a captured image captured by the imaging device, The program correction means is an image picked up by the image pickup device when the operation control means moves the robot based on the teaching program so that the hitting point is located near the axis of the welding tip. A surface direction orthogonal to the axial direction of the welding tip in robot tool coordinates based on the difference between the position of the hitting point in the image and the preset optimum hitting point position in the captured image stored in the storage means The robot teaching position in the teaching program is set to the welding tip in robot tool coordinates so that the difference between And correcting the surface direction perpendicular to the axial direction of the.
Here, the optimal hitting point position refers to a hitting point position set in advance by the user, and the optimum determination is made by the user.
The predetermined value is a value determined by the user, and the magnitude of the predetermined value is determined based on an allowable error.

  According to a fourth aspect of the present invention, in the welding teaching position correcting system according to the third aspect, the welding opening / closing axis for driving the welding tip in the axial direction by the operation control means or the robot in the robot tool coordinates. A detecting means for detecting that the welding tip is in contact with the workpiece when the tip is moved in the axial direction of the tip; and the program correcting means is configured to detect when the detecting means detects the contact of the welding tip with the workpiece. Based on the position of the robot in the axial direction of the welding tip at the robot tool coordinates, the teaching position of the robot in the teaching program is corrected in the axial direction of the welding tip at the robot tool coordinates.

According to a fifth aspect of the present invention, in the welding teaching position correction system according to the third aspect, the operation control means causes the hitting point portion to be positioned in the vicinity of the axis of the welding tip based on the teaching program. A gun opening / closing shaft or a robot for driving the welding tip in the axial direction by the operation control means, comprising a spot size storage means for storing the size of the spot when the robot is moved. Is moved in the axial direction of the welding tip in the robot tool coordinates, the size of the hit point portion in the captured image taken by the imaging device and the size of the hit point portion stored in the hit point size storage means And the size of the hit point portion in the captured image is the size of the hit point portion stored in the hit point portion size storage means. Difference and corrects a teaching position of the robot in the teaching program to be equal to or less than a predetermined value in the axial direction of the welding tip of the robot tool coordinate.
Here, the predetermined value is a value determined by the user, and the magnitude of the predetermined value is determined based on an allowable error.

  A sixth aspect of the present invention is the welding teaching position correction system according to any one of the first to fifth aspects, further comprising a wireless communication device that connects the imaging device and the image processing means by wireless communication. It is characterized by.

  According to a seventh aspect of the present invention, there is provided a calibration method for calibrating the imaging device when the teaching program is corrected using the welding teaching position correcting system according to any one of the first to sixth aspects. A first moving step of moving the robot so that the hitting point is near the axis of the welding tip based on the teaching program by the operation control means; and the robot is moved by the first moving step. Later, a first imaging step of imaging the hitting point by the imaging device, and the robot in the robot tool coordinates in a preset direction on a plane orthogonal to the optical axis of the imaging device in advance by the operation control means A second movement step of moving the robot by a set distance; and after moving the robot through the second movement step, A second imaging step of imaging the hit point portion, a position of the hit point portion in the captured image captured by the first imaging step, and a position of the hit point portion in the captured image captured by the second imaging step Based on the direction and distance in which the robot has been moved in the second moving step and the optimum spot position set in advance in the captured image, the optimum spot position in which the spot portion in the captured image is preset. A calculation step for calculating a movement direction and a movement distance of the robot necessary for moving the robot to the position, and a calibration for moving the robot by the operation control unit based on the movement direction and the movement distance calculated by the calculation step And a process.

  The invention according to claim 8 is a calibration method for calibrating the imaging apparatus when correcting the teaching program using the welding teaching position correcting system according to any one of claims 1 to 6. A first moving step of moving the robot so that a specific point located at a predetermined distance from the striking point portion is located near the axis of the welding tip by the operation control means based on the teaching program; A first imaging step of imaging the specific point by the imaging device after moving the robot by a moving step; and a plane orthogonal to the optical axis of the imaging device in robot tool coordinates by the operation control means. A second movement step of moving the robot in a preset direction above by a preset distance, and the robot by the second movement step. A second imaging step of imaging the specific point by the imaging device, a position of the specific point in the captured image captured by the first imaging step, and an image captured by the second imaging step. The specific point in the captured image is determined based on the position of the specific point in the image, the direction and distance in which the robot is moved in the second movement step, and the optimum hit point position set in advance in the captured image. Based on the calculation step for calculating the movement direction and the movement distance of the robot necessary for moving to the optimum hitting point position set in advance, and the movement control means based on the movement direction and the movement distance calculated by the calculation step And a calibration step for moving the robot.

  According to the first aspect of the present invention, the imaging device is configured such that the optical axis of at least one of the two welding tips of the spot welding gun provided at the tip of the robot is coaxial with the axis of the welding tip. Or an imaging device is attached to at least one welding tip so that the optical axis is coaxial with the axis of the welding tip. And the spotting part of the workpiece | work by a welding tip is imaged with an imaging device. The image processing means performs image processing of the captured image captured by the imaging device, and acquires position information of the hit point portion of the workpiece by the welding tip in the captured image. The program correcting unit corrects the teaching position of the robot in the teaching program in a plurality of directions based on the position information of the hit point portion of the workpiece in the captured image acquired by the image processing of the captured image.

  Here, the imaging device is provided so that the optical axis thereof is coaxial with the axis of the welding tip, so that the axis of the welding tip and the optical axis of the camera do not coincide with each other as in the prior art. In other words, the teaching of the robot operation for recognizing the work with the camera is not necessary, and the time and effort required for offline teaching can be reduced. In addition, since it is not necessary to calibrate the imaging apparatus in advance, it is possible to reduce the time and effort required for offline teaching and to suppress the occurrence of errors due to the calibration accuracy of the imaging apparatus.

  In addition, since the imaging device is detachably attached to one welding tip or replaceable with one welding tip, the imaging device only occupies the vicinity of the welding tip or the attachment region of the welding tip. As a result, the robot or spot welding gun interferes with the surrounding workpieces and jigs when the imaging device is in a posture to image the hitting portion and the imaging device pursues a posture suitable for imaging the hitting portion. The risk of doing so can be reduced. Therefore, it is not necessary to take a measure for avoiding such interference, and it is possible to reduce time and effort required for offline teaching.

  The program correcting means corrects the teaching position of the robot in the teaching program in a plurality of directions based on the position information of the hit point portion of the workpiece in the captured image. As a result, the correction can be made in a plurality of directions compared to the correction in one direction in the past, so that the correction accuracy can be improved.

  According to the second aspect of the present invention, the imaging device is configured such that the optical axis of at least one of the two welding tips of the spot welding gun fixed to the floor is coaxial with the axis of the welding tip. Or an imaging device is attached to at least one welding tip so that the optical axis is coaxial with the axis of the welding tip. And the spotting part of the workpiece | work by a welding tip is imaged with an imaging device. The image processing means performs image processing of the captured image captured by the imaging device, and acquires position information of the hit point portion of the workpiece by the welding tip in the captured image. The program correcting unit corrects the teaching position of the robot in the teaching program in a plurality of directions based on the position information of the hit point portion of the workpiece in the captured image acquired by the image processing of the captured image.

  Here, the imaging device is provided so that the optical axis thereof is coaxial with the axis of the welding tip, so that the axis of the welding tip and the optical axis of the camera do not coincide with each other as in the prior art. In other words, the teaching of the robot operation for recognizing the work with the camera is not necessary, and the time and effort required for offline teaching can be reduced. In addition, since it is not necessary to calibrate the imaging apparatus in advance, it is possible to reduce the time and effort required for offline teaching and to suppress the occurrence of errors due to the calibration accuracy of the imaging apparatus.

  In addition, since the imaging device is detachably attached to one welding tip or replaceable with one welding tip, the imaging device only occupies the vicinity of the welding tip or the attachment region of the welding tip. As a result, the robot or spot welding gun interferes with the surrounding workpieces and jigs when the imaging device is in a posture to image the hitting portion and the imaging device pursues a posture suitable for imaging the hitting portion. The risk of doing so can be reduced. Therefore, it is not necessary to take a measure for avoiding such interference, and it is possible to reduce time and effort required for offline teaching.

  The program correcting means corrects the teaching position of the robot in the teaching program in a plurality of directions based on the position information of the hit point portion of the workpiece in the captured image. As a result, the correction can be made in a plurality of directions compared to the correction in one direction in the past, so that the correction accuracy can be improved.

  According to the third aspect of the present invention, when the robot is moved based on the teaching program by the operation control means so that the hitting point is located near the axis of the welding tip, the optical axis of the imaging device and the welding tip Since the axis is on the same axis, the position of the hit point portion in the picked-up image taken by the image pickup device should match the preset optimum hit point position in the picked-up image stored in the storage means. However, they may not match due to installation errors of the robot, processing accuracy of the robot or spot welding gun, deflection due to its own weight, and the like.

In such a case, the program correction means is configured to weld the welding tip at the robot tool coordinates based on the difference between the position of the hitting point in the captured image captured by the imaging device and the preset optimal hitting point position in the captured image. The teaching position of the robot in the teaching program is corrected to the surface direction orthogonal to the axial direction of the welding tip in the robot tool coordinates so that the difference in the surface direction orthogonal to the axial direction is equal to or less than a predetermined value.
As a result, even if robot installation error, robot or spot welding gun processing accuracy, deflection due to its own weight, etc. occur, these errors are accepted and the error is eliminated by the program correction means. Can be increased.

  According to the fourth aspect of the present invention, when the welding tip is positioned with respect to the workpiece based on the teaching program by the operation control means, the gun opening / closing axis or the robot is determined in the axial direction of the welding tip in the robot tool coordinates. The welding tip should come into contact with the workpiece by moving the distance. However, they may not match due to installation errors of the robot, processing accuracy of the robot or spot welding gun, deflection due to its own weight, and the like.

In such a case, the program correction unit is configured to teach the robot in the teaching program based on the position of the robot in the axial direction of the welding tip in the robot tool coordinates when the detecting unit detects contact of the welding tip with the workpiece. Correct the position in the axial direction of the welding tip in robot tool coordinates.
As a result, even if robot installation errors, robot and spot welding gun processing accuracy, deflection due to its own weight, etc. occur, these errors are accepted, and the errors are eliminated by the program correction means. Can be done.
Further, by combining with correction of the surface direction orthogonal to the axial direction of the welding tip in claim 3, correction in all directions in the three-dimensional space can be performed, so that the correction accuracy can be improved.

  According to the fifth aspect of the present invention, when the robot is moved based on the teaching program by the operation control means so that the hitting point is located near the axis of the welding tip, the optical axis of the imaging device and the welding tip Since the axis is on the same axis, the size of the hit point portion in the captured image taken by the imaging device should match the size of the hit point portion stored in the hit point size storage means. However, the distance from the welding tip to the workpiece may change due to the installation error of the robot, the processing accuracy of the robot or spot welding gun, the deflection due to its own weight, and so on.

In such a case, the program correcting means captures an image captured by the imaging device when the gun opening / closing axis for driving the welding tip in the axial direction or the robot is moved in the axial direction of the welding tip in the robot tool coordinates. On the basis of the size of the hitting point portion in FIG. 5 and the size of the hitting point portion stored in the hitting point size storage unit, the size of the hitting point portion in the captured image matches the size of the hitting point portion stored in the hitting point size storage unit. Next, the teaching position of the robot in the teaching program is corrected in the axial direction of the welding tip in the robot tool coordinates.
As a result, even if robot installation error, robot or spot welding gun processing accuracy, deflection due to its own weight, etc. occur, these errors are accepted and the error is eliminated by the program correction means. Can be increased.

  According to the sixth aspect of the present invention, by wirelessly connecting the imaging device and the image processing means using a wireless communication device, the wiring for connecting the imaging device and the image processing means and the work area associated with the wiring can be reduced. There is no need to consider restrictions and the like, and the degree of freedom of arrangement of each device can be increased.

  According to the seventh aspect of the present invention, when the robot is moved in the first movement step so that the hitting point is located near the axis of the welding tip based on the teaching program, the optical axis of the imaging device and the welding Since the axis of the chip is coaxial, in the first imaging step, the position of the hit point portion in the captured image captured by the imaging device and the optimum spot position set in advance in the captured image should match. However, they may not match due to installation errors of the robot, processing accuracy of the robot or spot welding gun, deflection due to its own weight, and the like.

In such a case, in the second movement step, the robot is moved by a preset distance in a preset direction on a plane orthogonal to the optical axis of the imaging device in the robot tool coordinates. Next, in the second imaging step, after the robot is moved in the second moving step, the hitting portion is imaged by the imaging device. Next, in the calculation step, the position of the hit point portion in the captured image picked up in the first image pickup step, the position of the hit point portion in the picked-up image picked up in the second image pickup step, and the robot are moved in the second moving step. Based on the direction and distance and the preset optimum hit point position in the captured image, the movement direction and distance of the robot necessary for moving the hit point portion in the captured image to the preset optimum hit point position Is calculated. In the calibration step, the robot is moved and calibrated based on the movement direction and the movement distance calculated in the calculation step.
As a result, even if the direction of the captured image and the distance from the optimal optimal hit point position of the captured image to the hit point portion are unknown, the direction of the captured image and the captured image can be changed by moving the robot in the second movement step. Since the distance from the preset optimal hit point position to the hit point portion can be calculated, calibration can be performed accurately, and the correction accuracy of the teaching program can be improved.

  According to the eighth aspect of the present invention, in the first movement step, when the robot is moved so that the specific point is located near the axis of the welding tip based on the teaching program, the optical axis of the imaging device and the welding Since the axis of the chip is coaxial, in the first imaging step, the position of the specific point in the captured image captured by the imaging device should match the preset optimum spot position in the captured image. However, they may not match due to installation errors of the robot, processing accuracy of the robot or spot welding gun, deflection due to its own weight, and the like.

In such a case, in the second movement step, the robot is moved by a preset distance in a preset direction on a plane orthogonal to the optical axis of the imaging device in the robot tool coordinates. Next, in the second imaging step, after moving the robot in the second movement step, the specific point is imaged by the imaging device. Next, in the calculation process, the position of the specific point in the captured image captured in the first imaging process, the position of the specific point in the captured image captured in the second imaging process, and the robot is moved in the second movement process. Based on the direction and distance and the preset optimum hit point position in the captured image, the moving direction and distance of the robot necessary for moving the specific point in the captured image to the preset optimum hit point position Is calculated. In the calibration step, the robot is moved and calibrated based on the movement direction and the movement distance calculated in the calculation step.
As a result, even if the orientation of the captured image and the distance from the optimal optimum spot position of the captured image to the specific point are unknown, the orientation of the captured image and the captured image can be changed by moving the robot in the second movement step. Since the distance from the preset optimal hit point position to the specific point can be calculated, calibration can be performed accurately, and the correction accuracy of the teaching program can be improved.

Hereinafter, the best embodiment of a welding teaching position correction system and a calibration method will be described in detail with reference to the drawings. In correcting the welding teaching position, the direction orthogonal to the axial direction of the welding tip is the X direction, the direction orthogonal to the axial direction of the welding tip and orthogonal to the X direction is the Y direction, and the direction along the axial direction of the welding tip. Is the Z direction.
<Configuration of welding teaching position correction system>
As shown in FIG. 1, a welding teaching position correction system 1 includes a multi-axis robot 2 having a plurality of joints and arms, a spot welding gun 3 provided at the tip of the robot 2, and spot welding using a spot welding gun. An image of a captured image captured by the camera 4, a control device 5 that controls the operation of the robot 2, the spot welding gun 3, the camera 4, and the like. And an image processing device 6 that performs processing.

(robot)
As shown in FIG. 1, the robot 2 is used, for example, in a spot welding line of a body frame of an automobile. The robot 2 includes a base 21 serving as a base, a plurality of arms 23 connected by joints 22, and a servo motor (not shown) that drives the robot 2. And the spot welding gun 3 is provided in the front-end | tip part of each arm 23 connected.
Each joint 22 is one of a swing joint that pivots one end of the arm 23 and pivotally supports the other end thereof, and a rotary joint that pivotally supports the arm 23 so that the arm 23 itself can rotate around its longitudinal direction. Composed. That is, the robot 2 corresponds to a so-called articulated robot.

(Spot welding gun)
As shown in FIGS. 1 and 2, the spot welding gun 3 includes two welding tips (electrodes) 31 and 32. One welding tip 31 is fixed together with the arm 33. The other welding tip 32 is driven together with the arm 33 toward the one welding tip 31 by driving the gun opening / closing shaft 35 by a servo motor (not shown). The welding tips 31 and 32 are disposed so as to face each other. That is, the workpiece W can be held between the welding tips 31 and 32 by driving the gun opening / closing shaft 35 by the servo motor and narrowing the interval between the welding tip 31 and the welding tip 32. Then, spot welding can be performed by energizing the welding tips 31 and 32 with the workpiece W sandwiched between the welding tips 31 and 32. The servo motor is driven and controlled by a control signal from the control device 5.

(camera)
As shown in FIG. 2, for example, a small CCD camera is used as the camera 4. The camera 4 is detachably attached to at least one of the two welding tips 31 and 32. At this time, the camera 4 is provided so that its optical axis is coaxial with the axis of the welding tip 31. The camera 4 may be provided on either of the two welding tips 31 and 32, but is preferably provided on the welding tip 31 fixed to the arm 33. This is to reduce the occurrence probability of the optical axis shift due to the movement of the welding tip 32.
As shown in FIG. 3, at least one welding tip 31 may be detached from the arm 33, and the camera 4 may be provided at the removed position. In other words, the welding tip 31 and the camera 4 may be provided to be exchangeable with respect to the arm 33. In the present embodiment, an example in which the welding tip 31 and the camera 4 are replaced will be described.
As shown in FIG. 4, the camera 4 is provided with a communication device 91 that is connected to the image processing device 6 by wireless communication and constitutes the wireless communication device 9. The communication device 91 transmits the captured image data captured by the camera 4 to the communication device 92 for image processing by the image processing device 6.
Note that the camera 4 used has a characteristic that the focal range is wide (the focal depth range is long) in order to reliably recognize the hit point even when an error occurs in the distance between the workpiece W and the camera 4. It is desirable to use

(Control device)
As shown in FIG. 4, the control device 5 includes a CPU 51 that executes each process according to a process program related to operation control of the robot 2, and a memory 52 that stores a process program, process data, and the like for executing each process. It is equipped with.
The memory 52 is provided with a program area 53 for storing a processing program for driving the robot 2, a data area 54 for storing data necessary for driving control of the robot 2, various work memories, counters, and the like. A work area 55 in which each process is performed is formed.

The program area 53 stores a teaching program 53a for realizing the function of teaching the welding operation to the robot 2 and the spot welding gun 3 and performing the operation control.
In the program area 53, a plurality of teaching positions of the robot 2 in the teaching program 53a are set based on the position information of the hit point portion of the workpiece W in the captured image acquired by the image processing of the captured image transmitted from the image processing device 6. The correction program 53b for realizing the function of correcting in the direction is stored. That is, the control device 5 receives a plurality of position component correction values for correcting the teaching program 53 a from the image processing device 6 and stores them in the data area 54. Then, when the correction program 53b is executed, the correction value is read from the data area 54 to correct the teaching program 53a.
In the program area 53, calibration for correcting a deviation between the position of the robot 2 (the position of the robot in the camera coordinates) and the actual position of the robot 2 (the position of the robot in the robot tool coordinates) in the captured image captured by the camera 4 is performed. A storage program 53c is stored.

The control device 5 is provided with an input device 7 to which an operation instruction from the user is input, and a display device 8 that displays information to be notified to the user, such as an image captured by the camera 4.
The input device 7 and the display device 8 may be provided in the main body of the control device 5, or provided in a pendant connected to the main body of the control device 5 by wire or wireless in order to realize remote operation. It may be done.

(Image processing device)
As shown in FIG. 4, the image processing apparatus 6 stores a CPU 61 that executes each process in accordance with an image processing program of a captured image captured by the camera 4, a processing program and process data for executing each process, and the like. And a memory 62.
The memory 62 is provided with a program area 63 for storing an image processing program for captured images, a data area 64 for storing data necessary for image processing, various work memories, counters, and the like. The work area 65 to be performed is formed.

In the program area 63, an analysis program 63a for realizing a function of performing image processing of a captured image captured by the camera 4 and acquiring position information of a work spot portion by the welding tips 31 and 32 in the captured image is stored. Has been.
In the program area 63, an XY correction value calculation program 63b for calculating correction values for correcting the position components in the X direction and the Y direction when the control device 5 corrects the teaching program 53a is stored.
The program area 63 stores a Z correction value calculation program 63c for calculating a correction value for correcting a position component in the Z direction when the control device 5 corrects the teaching program 53a.

  The data area 64 stores an optimal spot position (for example, the center position of the imaging area) in a preset imaging area, and the data area 64 functions as a storage unit. Note that the optimum hit point position in the preset imaging region is not limited to that stored in the data area 64 of the image processing device 6, and may be stored in the data area 54 of the control device 5. At this time, the data area 54 functions as a storage means.

  The image processing device 6 is provided with a communication device 92 that is connected to the camera 4 by wireless communication and constitutes the wireless communication device 9. The communication device 92 receives the captured image data captured by the camera 4 from the communication device 91 so that the image processing device 6 performs image processing.

FIG. 5 is a block diagram illustrating functions of the welding teaching position correction system 1.
The welding teaching position correction system 1 includes a robot control unit 10 that controls the operation of the robot 2. The function of the robot control unit 10 is borne by the control device 5.
The robot control unit 10 includes an operation control unit 11 that transmits an operation signal to the robot 2 to control the operation of the robot 2, the spot welding gun 3, and the like by the CPU 51 executing the teaching program 53a. The operation control unit 11 functions as an operation control unit.
The robot control unit 10 includes a correction unit 12 that corrects the teaching program 53a based on the correction value received from the image processing device 6 when the CPU 51 executes the correction program 53b. The correction unit 12 functions as a program correction unit.
The robot control unit 10 includes a calibration unit 13 that corrects a deviation between the position of the robot 2 in the camera coordinates and the position of the robot in the robot tool coordinates by the CPU 51 executing the calibration program 53c.

The welding teaching position correction system 1 has a robot operation unit 14 that operates based on a control signal from the robot control unit 10. The function of the robot operation unit 14 is performed by a driving part of the robot 2 such as the arm 23.
The welding teaching position correction system 1 includes a welding unit 15 that performs spot welding on the workpiece W by being driven by the operation of the robot operation unit 14. The function of the welded portion 15 is performed by the spot welding gun 3 including the two welding tips 31 and 32.
The welding teaching position correction system 1 includes an image pickup unit 16 that picks up an image of a hitting point portion of a workpiece by the welding tips 31 and 32. The camera 4 has the function of the imaging unit 16.
The welding teaching position correction system 1 includes a detection unit 17 that detects that the welding tip 32 has contacted the workpiece. The function of the detection unit 17 is performed by the pressure sensor 34 provided on the welding tip 32. Note that the pressure sensor 34 is provided on the welding tip 32 only when the teaching program 53a is corrected. When welding is actually performed, the welding tip 32 is replaced with the normal welding tip 32 to perform the work. That is, the pressure sensor 34 is used when correcting the position in the Z direction. A detection signal detected by the pressure sensor 34 is wirelessly transmitted via the communication device 91 and the communication device 92 and sent to the image processing device 6.
The welding teaching position correction system 1 includes a communication unit 18 that wirelessly connects the imaging unit 16 or the detection unit 17 and the image processing unit 19. The function of the communication unit 18 is borne by the wireless communication device 9.

The welding teaching position correction system 1 includes an image processing unit 19 that performs image processing of a captured image captured by the imaging unit 16. The function of the image processing unit 19 is performed by the image processing apparatus 6.
The image processing unit 19 performs image processing of the captured image captured by the imaging unit 16 by the CPU 61 executing the analysis program 63a, and the position of the spot portion of the workpiece W by the welding tips 31 and 32 in the captured image. It has the analysis part 20 which analyzes information. The analysis unit 20 functions as an image processing unit.
When the CPU 61 executes the XY correction value calculation program 63b, the image processing unit 19 operates the robot so that the hitting portion is positioned near the axis of the welding tips 31 and 32 based on the teaching program 53a by the operation control unit 11. When the part 14 is moved, the position of the hit point portion in the captured image captured by the camera 4 and the position in the imaging region of the preset optimal hit point position (for example, the position of the center of the image capturing region in the captured image) ), The teaching position of the robot 2 in the teaching program 53a in the robot tool coordinates so that the difference in the surface direction orthogonal to the axial direction of the welding tips 31, 32 in the robot tool coordinates is equal to or less than a predetermined value. XY correction value calculation unit 21 for correcting in the X and Y directions. The XY correction value calculation unit 21 functions as a program correction unit. Here, “below the predetermined value” ideally means that the difference in the surface direction perpendicular to the axial direction of the welding tips 31 and 32 in the robot tool coordinates becomes zero.
In the image processing unit 19, the CPU 61 executes the Z correction value calculation program 63 c so that the pressure sensor 34 serving as a detection unit that detects the contact of the welding tip 32 with the workpiece W by the contact with the workpiece W includes the welding tip 32. Based on the position of the robot 2 in the axial direction of the welding tip 32 in the robot tool coordinates when contact with the workpiece W is detected, the teaching position of the robot 2 in the teaching program 53a is changed to the axis of the welding tip 32 in the robot tool coordinates. A Z-direction correction value calculation unit 22 that corrects the direction is provided. The Z correction value calculation unit 22 functions as a program correction unit.

<Teaching position correction processing by welding teaching position correction system>
The teaching position correction processing by the welding teaching position correction system will be described by dividing it into correction in the X and Y directions and correction in the Z direction.
(Correction in X direction and Y direction)
As shown in FIG. 6, when the CPU 51 of the control device 5 executes the teaching program 53a, the robot 2 is moved so that the hit point portion of the workpiece is positioned near the axis of the welding tip 32 (step S1).
Next, the CPU 51 sends an imaging command signal to the camera 4 to cause the camera 4 to image the hit point portion of the work (step S2).
Then, the CPU 51 wirelessly transmits the image data of the captured image to the communication device 92 via the communication device 91. The communication device 92 that has received the image data of the captured image sends the image data to the image processing device 6 (step S3).
Next, the CPU 61 of the image processing device 6 executes image analysis of the image data by executing the analysis program 63a, and analyzes the position information of the hit point portion of the work in the captured image. Then, the CPU 61 executes the XY correction value calculation program 63b to calculate the XY correction value from the position information of the hit point portion of the workpiece in the captured image and the position information of the optimum hit point position of the captured image area. (Step S4), the data is transmitted to the control device 5.
Next, the CPU 51 executes the correction program 53b, thereby correcting the teaching program 53a based on the calculated XY correction value, updating it to the corrected program (step S5), and this processing is terminated.

Here, the correction processing in the X direction and the Y direction will be described with specific examples.
Assume that the captured image when the robot 2 is moved so that the hit point portion of the workpiece W is positioned near the axis of the welding tip 32 and the hit point portion M is picked up by the camera 4 is as shown in FIG.
In such a state, when the CPU 61 executes the analysis program 63a, the CPU 61 obtains the optimum spot position coordinates (0, 0) of the imaging region R and the center position coordinates (x1, y1) of the spot portion M. . Then, the CPU 61 executes the XY correction value calculation program 63b so that the center position coordinate of the hit point portion M comes to the optimum hit point position coordinate (0, 0) of the imaging region R in the captured image. The correction value of the teaching program 53a is calculated. In this case, since the center position coordinates of the hit point M are moved by −x1 in the X direction and −y1 in the Y direction, the both position coordinates coincide with each other, and this correction value is transmitted to the control device 5. Then, the CPU 51 of the control device 5 executes the correction program 53b, thereby adding the position coordinate data in the teaching program 53a by -x1 in the X direction and by -y1 in the Y direction, and executing the teaching program 53a. to correct.

(Z direction correction)
As shown in FIG. 8, when the CPU 51 of the control device 5 executes the teaching program 53a, the robot 2 is moved so that the welding tip 32 approaches the workpiece (step S11).
Next, the CPU 61 of the image processing device 6 determines whether or not the pressure sensor 34 has received a detection signal for detecting contact with the workpiece W (step S12). Here, when the CPU 61 determines that the pressure sensor 34 has received a detection signal for detecting contact with the workpiece W (step S12: YES), the CPU 61 determines the position of the robot when the pressure sensor 34 contacts the workpiece. Is extracted (step S13).
Next, the CPU 61 executes the Z correction value calculation program 63c to calculate a Z correction value from the position coordinates of the robot 2 extracted in step S13 and the position coordinates of the robot 2 based on the teaching program 53a (step S14). It transmits to the control apparatus 5.
Next, the CPU 51 of the control device 5 executes the correction program 53b to correct the teaching program 53a based on the calculated Z correction value, and updates the corrected program (step S15). End.

Here, the correction process in the Z direction will be described with a specific example.
Assume that the robot 2 is moved so that the welding tip 32 approaches the workpiece, and the position of the robot 2 when the pressure sensor 34 contacts the workpiece is the position of the solid line in FIG. 9.
In such a state, assuming that the position of the robot 2 based on the teaching program 53a is the position of the chain line in FIG. 9, the CPU 61 executes the Z correction value calculation program 63c to thereby obtain a difference z1 between the two positions in the Z direction. Is calculated. In this case, since the position coordinates coincide by moving the robot 2 in the Z direction by −z1, this correction value is transmitted to the control device 5. Then, the CPU 51 of the control device 5 executes the correction program 53b, thereby adding the position coordinate data in the teaching program 53a by -z1 in the Z direction to correct the teaching program 53a.

<XY correction value calculation processing>
A process for calculating the XY correction value from the position information of the hit point portion in the captured image captured by the camera and the position information of the optimum hit point position of the captured image area will be described.
After the camera 4 is attached to the arm 33, as shown in FIG. 10, when the XY correction value calculation process is started, the CPU 51 of the control device 5 has a hitting point near the axis of the welding tip 32 based on the teaching program 53a. The robot 2 is moved so as to move (step S21: first movement step).
Next, the CPU 51 issues an imaging request to the image processing apparatus 6 and causes the camera 4 to image the hit point portion (step S22: first imaging step).
Next, the CPU 51 moves the robot 2 on the XY plane by a preset distance in a direction preset by the calibration program 53c (step S23: second movement process).
Next, the CPU 51 issues an imaging request to the image processing apparatus 6 and causes the camera 4 to image the hit point portion (step S24: second imaging step).
Next, the CPU 51 stores the position of the hit point portion in the captured image captured in step S22, the position of the hit point portion in the captured image captured in step S24, the direction and distance in which the robot is moved in step S23, and data in advance. The moving direction of the robot 2 necessary for moving the hit point portion in the captured image to the center position of the imaged area based on the optimum spot position in the captured image stored in the area 64, for example, the center position of the imaged area. Then, the movement distance, that is, the XY correction value is calculated (step S25: calculation step).
Next, the CPU 51 corrects the teaching program 53a based on the XY correction value calculated in step S25 (step S26: teaching program correcting step).

となる。
この式に基づき、例えば、最適な打点位置を撮像領域Ｒの中心座標（０，０）とすると、ロボット２のＸ補正量Ｌｘ及びＹ補正量Ｌｙは、以下の各式で算出することができる。

そして、ＣＰＵ５１は、これらの式に基づいて算出された補正量Ｌｘ，Ｌｙに基づいて、教示プログラム５３ａを補正する。 Here, the XY correction value calculation process will be described with a specific example.
The captured image when the robot 2 is moved so that the hit point portion of the workpiece W is positioned near the axis of the welding tip 32 and the hit point portion M1 is picked up by the camera 4 is in a state as shown in FIG. Suppose. In such a state, the CPU 51 moves the robot 2 in the direction and distance set in advance by the calibration program 53c. Here, it is assumed that when the robot tool coordinates are moved by a distance L in the X direction, the state shown in FIG.
In this case, since the robot 2 is moved only in the X direction, it can be seen that the direction of the line connecting the hit point M1 and the hit point M2 with a straight line corresponds to the movement on the robot tool coordinates. It can also be seen that the direction orthogonal to the X direction is the Y direction. Now, the Y direction is a direction obtained by rotating the X axis by 90 ° on the captured image.
Further, assuming that the XY position coordinates of the hit point M1 are (x1, y1) and the XY position coordinates of the hit point M2 are (x2, y2), the vectors of the X and Y directions of the robot tool coordinates on the camera coordinates are respectively ,

It becomes.
Based on this equation, for example, if the optimum hit point position is the center coordinate (0, 0) of the imaging region R, the X correction amount Lx and the Y correction amount Ly of the robot 2 can be calculated by the following equations. .

The CPU 51 corrects the teaching program 53a based on the correction amounts Lx and Ly calculated based on these equations.

<Effect>
According to the above embodiment, the optical axis is coaxial with the axis of the welding tip 32 instead of one of the two welding tips 31 and 32 of the spot welding gun 3 provided at the tip of the robot 2. Attach the camera 4 as follows. Then, the camera 4 picks up an image of the spotted portion of the workpiece by the welding tip 32. The image processing device 6 performs image processing of the captured image captured by the camera 4 and acquires position information of the hitting point portion of the workpiece by the welding tip 32 in the captured image. And the control apparatus 5 correct | amends the teaching position of the robot 2 in the teaching program 53a in several directions based on the positional information on the hit | damage point part of the workpiece | work in the captured image acquired by the image processing of a captured image.

  Here, since the optical axis of the camera 4 is provided so as to be coaxial with the axis of the welding tip 32, the axis of the welding tip 32 and the optical axis of the camera 4 do not coincide with each other as in the prior art. Therefore, it is not necessary to teach the robot operation for recognizing the work by the camera 4, that is, it is possible to reduce the labor for offline teaching. In addition, since it is not necessary to calibrate the camera 4 in advance, it is possible to reduce the time and effort required for offline teaching and to suppress the occurrence of errors due to the calibration accuracy of the camera 4.

Further, since the camera 4 can be exchanged with one welding tip 31, the camera 4 only occupies the attachment region of the welding tip 31. As a result, when the camera 4 takes a posture for imaging the hit point portion, the robot 2 and the spot welding gun 3 are too close to the workpieces and jigs around the pursuit of a posture suitable for the shooting of the hit point portion with the camera 4. The possibility of interfering with can be reduced. Therefore, it is not necessary to take a measure for avoiding such interference, and it is possible to reduce time and effort required for offline teaching.
In addition, since the confirmation work that has been performed by the worker can be automated, labor costs can be reduced and equipment preparation costs can be reduced.
In addition, it is possible to eliminate a variation in work quality by an operator and to create a teaching program 53a with stable accuracy.
Furthermore, in the case of a welding line that uses a large number of robots, the program confirmation / correction work for a plurality of robots can be performed simultaneously, so that the work can be completed in a short time and the equipment start-up preparation period can be shortened.

Further, the control device 5 determines the robot based on the difference between the position of the hit point portion in the captured image captured by the camera 4 and a preset optimal hit point position (for example, the center position of the image capturing area) in the captured image. The teaching position of the robot 2 in the teaching program 53a is corrected in the XY plane direction at the robot tool coordinates so that the difference in the XY plane direction at the tool coordinates is not more than a predetermined value (for example, the difference is zero).
Further, the control device 5 determines the teaching position of the robot 2 in the teaching program 53a based on the position of the robot 2 in the Z direction in the robot tool coordinates when the pressure sensor 34 detects contact of the welding tip 32 with the workpiece. Correct in the Z direction in robot tool coordinates.
As a result, even if the installation error of the robot 2, the processing accuracy of the robot 2 or the spot welding gun 3, or the deflection due to its own weight occurs, the error is eliminated by the correction program 53 b after the errors are accepted. Can improve the accuracy.
In addition, since correction in all directions (XYZ directions) in the three-dimensional space can be performed, the accuracy of correction can be increased.

  In addition, by wirelessly connecting the camera 4 and the image processing device 6 using the wireless communication device 9, it is necessary to consider the wiring that connects the camera 4 and the image processing device 6, the work area restrictions associated with the wiring, and the like. Therefore, the degree of freedom of arrangement of each device can be increased.

  Further, when the robot 2 is moved based on the teaching program 53a so that the hitting point is located near the axis of the welding tip 32, the optical axis of the camera 4 and the axis of the welding tip 32 are coaxial. The position of the hit point portion M1 in the captured image captured by the camera 4 and the optimum hit point position set in advance in the captured image should match. However, they may not match due to installation error of the robot 2, processing accuracy of the robot 2 or spot welding gun 3, deflection due to its own weight, or the like.

In such a case, the robot 2 is moved by a preset distance in a preset direction on the XY plane in the robot tool coordinates. Next, after moving the robot 2, the hit point M <b> 2 is imaged by the camera 4. Next, based on the captured positions of the two hit points M1 and M2, the direction and distance in which the robot 2 is moved, and the optimal hit point position of the imaging region R in the captured image, the hit point M2 in the captured image is determined. The moving direction and moving distance of the robot 2 necessary for moving to the optimum hitting point position in the imaging region R are calculated. Then, the teaching program 53a of the robot 2 is corrected based on the calculated moving direction and moving distance.
As a result, even if the orientation of the captured image and the distance from the optimal hitting point position of the imaging region R of the captured image to the hitting point M1 are unknown, the orientation of the captured image and the imaging region R of the captured image can be obtained by moving the robot 2. Since the distance from the optimal hit point position to the hit point portion M2 can be calculated, the correction can be performed accurately and the correction accuracy can be increased.

<Others>
The present invention is not limited to the above embodiment. For example, when the teaching program 53a is corrected using the calculated correction value, the robot 2 is moved to the position where the calculated correction value is added, and the error is measured again to confirm that it is within a predetermined accuracy range. However, when it is out of the range, measurement and correction may be repeated until it falls within a predetermined accuracy range.
In addition, when the size of the hitting portion is stored in the data area 54 (the hitting portion size storing means) of the control device 5 and the gun opening / closing axis 35 or the robot 2 is moved in the Z direction in the robot tool coordinates, Based on the difference or ratio between the size of the dot portion in the captured image and the size of the dot portion stored in the data area 54, the difference between the size of the dot portion in the captured image and the size of the dot portion stored in the data area 54 May be corrected to the Z direction in the teaching program 53a in the teaching program 53a so as to be equal to or less than a predetermined value.
As a result, even if the installation error of the robot 2, the processing accuracy of the robot 2 or the spot welding gun 3, or the deflection due to its own weight occurs, the error is corrected after being accepted, so that the correction accuracy can be improved. Can do.

Further, when determining the correction amount of the teaching program 53a, the movement amount of the required robot 2 is calculated by calculating the positional deviation based on the hitting point portion of the welding tip 32 on the workpiece. The teaching program 53a may be corrected based on a specific point located at a predetermined distance. Note that the distance from the hitting point can be arbitrarily set, that is, the specific point may be at any position on the workpiece. In short, the teaching program 53a may be corrected based on some position on the workpiece.
As for the welding method using the robot, the spot welding gun 3 is fixed to the floor, and the robot provided with a gripping device for gripping the workpiece at the tip is moved toward the spot welding gun 3. Good.
Further, the program stored in the program area 53 may be a more fragmented program, or all the programs may be integrated.
Further, although the processing related to the correction of the teaching program 53a is performed by software, it may be configured to be processed by hardware.
Further, although the C-type spot welding gun is used as the welding gun, an X-type spot welding gun may be used.

The method for detecting that the welding tip 32 is in contact with the workpiece is not limited to the pressure sensor 34. For example, a weak current is passed through the welding tip 32 and the current value when the welding tip 32 comes into contact with the workpiece. Or the method of detecting that the welding tip 32 contacted the workpiece | work by detecting the change of a voltage value may be sufficient.
In the above embodiment, the camera 4 and the image processing device 6 are configured separately, but if a camera having an image processing function is used, the captured image is processed by the camera 4 and the image data is obtained. Can be wirelessly transmitted to the control device 5.
The control device 5 and the image processing device 6 are configured separately, but if the control device 5 has an image processing function, the image captured by the camera 4 is wirelessly transmitted to the control device 5. Thus, the control device 5 can perform image processing and control the robot 2 based on the data. These configurations can be freely changed according to the requests of workers and designers.
In addition, the design can be freely changed without departing from the essence of the invention.

1 is a schematic configuration diagram of a welding teaching position correction system. The front view of a spot welding gun. The front view of a spot welding gun. The block diagram which shows the structure of a welding teaching position correction system. The block diagram which shows the function of a welding teaching position correction system. The flowchart which shows the correction process of the XY direction of the teaching position determined by a teaching program. Explanatory drawing of the correction method of the XY direction of the teaching position determined by a teaching program. The flowchart which shows the correction process of the Z direction of the teaching position determined by a teaching program. Explanatory drawing of the correction method of the Z direction of the teaching position determined by a teaching program. The flowchart which shows XY correction value calculation processing. Explanatory drawing of a XY correction value calculation process.

Explanation of symbols

1 Welding teaching position correction system 2 Robot 3 Spot welding gun 4 Camera (imaging device)
9 Wireless communication device 11 Operation control unit (operation control means)
12 Correction unit (program correction means)
20 Analysis unit (image processing means)
21 XY correction value calculation unit (program correction means)
22 Z correction value calculation unit (program correction means)
31 Welding tip 32 Welding tip 34 Pressure sensor (detection means)
53a Teaching program 54 Data area (dot size storage means)
91 Communication device 92 Communication device W Work

Claims (8)

A robot having a plurality of joints;
A spot welding gun provided at the tip of the robot and having two welding tips arranged opposite to each other;
At least one welding tip is detachably provided or replaceable with at least one welding tip, and an optical axis is provided so as to be coaxial with the axis of the welding tip, and images a hitting point portion of the workpiece by the welding tip. An imaging device;
Operation control means for controlling the operation of the robot and the spot welding gun according to a teaching program for teaching the robot and the spot welding gun of a welding operation;
Image processing means for performing image processing of a picked-up image picked up by the image pick-up device and acquiring position information of a hitting point portion of the work by the welding tip in the picked-up image;
Program correction means for correcting the teaching position of the robot in the teaching program in a plurality of directions based on position information of a hitting point portion of the work in the captured image acquired by image processing of the captured image by the image processing means; ,
A welding teaching position correction system comprising: A spot welding gun having two welding tips fixed to the floor and arranged opposite to each other;
A robot having a plurality of joints, provided with a gripping device for gripping the workpiece at the tip, and supplying the workpiece to the spot welding gun;
At least one welding tip is detachably provided or replaceable with at least one welding tip, and an optical axis is provided so as to be coaxial with the axis of the welding tip, and images a hitting point portion of the workpiece by the welding tip. An imaging device;
Operation control means for controlling the operation of the robot and the spot welding gun according to a teaching program for teaching the robot and the spot welding gun of a welding operation;
Image processing means for performing image processing of a picked-up image picked up by the image pick-up device and acquiring position information of a hitting point portion of the work by the welding tip in the picked-up image;
Program correction means for correcting the teaching position of the robot in the teaching program in a plurality of directions based on position information of a hitting point portion of the work in the captured image acquired by image processing of the captured image by the image processing means; ,
A welding teaching position correction system comprising: Storage means for storing a preset optimum spot position in a captured image captured by the imaging device;
The program correction means is an image picked up by the image pickup device when the operation control means moves the robot based on the teaching program so that the hitting point is located near the axis of the welding tip. A surface direction orthogonal to the axial direction of the welding tip in robot tool coordinates based on the difference between the position of the hitting point in the image and the preset optimum hitting point position in the captured image stored in the storage means 3. The teaching position of the robot in the teaching program is corrected to a surface direction perpendicular to the axial direction of the welding tip in robot tool coordinates so that the difference between the teaching programs is equal to or less than a predetermined value. The welding teaching position correction system as described. Detection of contact of the welding tip with the workpiece when the gun opening / closing axis for driving the welding tip in the axial direction by the operation control means or when the robot is moved in the axial direction of the welding tip in robot tool coordinates Detecting means for
The program correction unit is configured to teach the robot in the teaching program based on the position of the robot in the axial direction of the welding tip in robot tool coordinates when the detection unit detects contact of the welding tip with the workpiece. The welding teaching position correcting system according to claim 3, wherein the position is corrected in the axial direction of the welding tip in robot tool coordinates. A spot size storage means for storing the size of the hit point when the robot is moved so that the hit point is located near the axis of the welding tip based on the teaching program by the operation control means. Prepared,
The program correction means picks up an image by the imaging device when the operation control means moves the gun opening / closing axis that drives the welding tip in the axial direction or the robot moves in the axial direction of the welding tip in robot tool coordinates. Based on the size of the hitting point portion in the captured image and the size of the hitting point portion stored in the hitting point size storage unit, the size of the hitting point portion in the captured image is stored in the hitting point size storage unit. 4. The teaching position of the robot in the teaching program is corrected in the axial direction of the welding tip in robot tool coordinates so that the difference from the size of the hitting point portion is a predetermined value or less. The welding teaching position correction system as described.   The welding teaching position correction system according to claim 1, further comprising a wireless communication device that connects the imaging device and the image processing unit by wireless communication. In the calibration method for calibrating the imaging device in performing the correction of the teaching program using the welding teaching position correcting system according to any one of claims 1 to 6,
A first moving step of moving the robot so that the hitting point is near the axis of the welding tip based on the teaching program by the operation control means;
A first imaging step of imaging the hitting point by the imaging device after moving the robot in the first movement step;
A second movement step of moving the robot by a preset distance in a preset direction on a plane orthogonal to the optical axis of the imaging device in robot tool coordinates by the operation control means;
A second imaging step of imaging the hitting point by the imaging device after moving the robot in the second movement step;
The position of the hit point portion in the captured image picked up in the first image pickup step, the position of the hit point portion in the picked-up image picked up in the second image pickup step, and the robot moved by the second moving step. Based on the direction and distance, and the optimal hit point position set in advance in the captured image, the moving direction of the robot necessary to move the hit point portion in the captured image to the preset optimal hit point position, and A calculation step for calculating a movement distance;
A calibration step of moving the robot by the motion control means based on the moving direction and moving distance calculated by the calculating step;
A calibration method comprising: In the calibration method for calibrating the imaging device in performing the correction of the teaching program using the welding teaching position correcting system according to any one of claims 1 to 6,
A first movement step of moving the robot so that a specific point located at a predetermined distance from the striking point portion is near the axis of the welding tip based on the teaching program by the operation control means;
A first imaging step of imaging the specific point by the imaging device after moving the robot in the first movement step;
A second movement step of moving the robot by a preset distance in a preset direction on a plane orthogonal to the optical axis of the imaging device in robot tool coordinates by the operation control means;
A second imaging step of imaging the specific point by the imaging device after moving the robot in the second movement step;
The position of the specific point in the captured image captured by the first imaging step, the position of the specific point in the captured image captured by the second imaging step, and the robot moved by the second moving step. Based on the direction and distance, and the optimal hit point position set in advance in the captured image, the moving direction of the robot necessary to move the specific point in the captured image to the preset optimal hit point position and A calculation step for calculating a movement distance;
A calibration step of moving the robot by the motion control means based on the moving direction and moving distance calculated by the calculating step;
A calibration method comprising:

Images