JP7290537B2 - Correction system, correction method, robot system and controller - Google Patents

Description

The present invention relates to a correction system, a correction method, a robot system and a control device.

Conventionally, a technique for automatically correcting robot teaching data is known. For example, Patent Literature 1 discloses a teaching position correction system for a welding robot. The taught position correction system includes an imaging device attached to or replaced by one of the two electrodes of the welding gun that are arranged to face each other. The optical axis of the imaging device is coaxial with the axis of the one electrode. The teaching position correction system allows the imaging device to perform welding based on the position information of the welding point of the workpiece in the image captured by the imaging device, the distance from the imaging device to the welding point, and the clearance between the workpiece and the other electrode. Correct the teaching position of the welding gun so that the point can be imaged.

JP 2008-132525 A

In the system of Patent Document 1, the imager is attached to or replaces one electrode of the welding gun. The length of the imaging device is generally greater than the length of the electrodes. For example, operating the electrodes of the welding gun to close the gap between the electrodes according to the teaching data may crush the imaging device. Therefore, for example, imaging with an imaging device is performed with a gap between the electrodes. In this case, the distance between the imaging device and the welding point increases, and the accuracy of the position information of the welding point obtained by processing the image of the welding point decreases, which may reduce the correction accuracy of the teaching position.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a correction system, a correction method, a robot system, and a control device that improve the correction accuracy of teaching data.

To achieve the above object, a correction system according to one aspect of the present invention is a correction system for correcting teaching data of a robot, comprising: a camera mounted on the first mounting part operable in a first direction; and mounting for mounting the camera on the first mounting part such that the direction of the optical axis of the camera is offset from the first mounting part. and a control device, wherein the control device teaches for pressing the first mounting portion against a predetermined hitting position of the workpiece between the first mounting portion and the second mounting portion according to the teaching data. When the robot gun is positioned at the position, causing the camera to image the dot mark attached to the predetermined dot position, detecting the position of the dot mark using the image captured by the camera, and A corresponding position, which is a position of the robot gun for pressing the first mounting portion against the dot mark, is detected, and the teaching data is corrected based on the difference between the corresponding position and the teaching position.

A robot system according to one aspect of the present invention includes the correction system according to one aspect of the present invention and the robot, and the controller controls the operation of the robot.

A correction method according to an aspect of the present invention is a correction method for correcting teaching data of a robot, wherein a workpiece between a first mounting section and a second mounting section facing each other of a robot gun of the robot is corrected in accordance with the teaching data. moving the robot gun to a teaching position for pressing the first mounting part against a predetermined hitting position; capturing an image of the dot mark attached to the predetermined dot position; detecting the position of the dot mark using the image captured by the camera; and attaching the first mounting portion to the dot mark. detecting a corresponding position that is the position of the robot gun for pressing; and correcting the teaching data based on a difference between the corresponding position and the teaching position, wherein the camera detects the light of the camera. Mounted on the first mounting such that the orientation of the axis is offset from the first mounting that is operable in a first direction.

A control device according to one aspect of the present invention is a control device that executes the correction method according to one aspect of the present invention.

According to the present invention, it is possible to improve the correction accuracy of teaching data.

Schematic diagram showing an example of a robot system according to an embodiment Side view showing an example of the configuration of the welding gun according to the embodiment 3 is a side view showing an example of a configuration in which an imaging device is attached instead of the electrode tip in the welding gun of FIG. 2. FIG. 1 is a block diagram showing an example of a hardware configuration of a robot system according to an embodiment; FIG. 1 is a block diagram showing an example of a functional configuration of a robot system according to an embodiment; FIG. FIG. 4 is a diagram showing an example of marking of the dot mark according to the embodiment; FIG. 11 is a side view showing an example of a state when the dot mark is imaged by the camera in the correction mode; FIG. 8 is a diagram showing an example of an image captured by a camera in the state of FIG. 7; 4 is a flowchart showing an example of operation in correction mode of the robot system according to the embodiment; The side view which shows an example of a structure of the imaging device of the welding gun which concerns on a modification.

First, an embodiment of the present invention will be described. A correction system according to one aspect of the present invention is a correction system that corrects teaching data of a robot, and is operable in a first direction of a first mounting portion and a second mounting portion of a robot gun of the robot that face each other. a camera mounted on the first mounting portion, a fixture for mounting the camera on the first mounting portion such that the direction of the optical axis of the camera is offset from the first mounting portion, and a control device. and the control device positions the robot gun at a teaching position for pressing the first mounting section against a predetermined hitting position of the workpiece between the first mounting section and the second mounting section according to the teaching data. Then, the dot mark attached to the predetermined dot position is imaged by the camera, the position of the dot mark is detected using the image captured by the camera, and the dot mark is attached to the first mounting portion. is detected, and the teaching data is corrected based on the difference between the corresponding position and the teaching position.

According to the above aspect, since the camera is attached to the first mounting portion so that the direction of the optical axis of the camera is offset, the amount of protrusion of the camera from the first mounting portion in the first direction can be suppressed. As a result, even if the first mounting part is moved in the first direction according to the teaching data, the camera is not crushed between the first mounting part and the workpiece when the camera takes an image, and the dot mark is approached. be able to. Therefore, the camera can take an image of the dot mark in a state in which the first mounting unit moves toward the dot position, and can capture an image showing the relative position of the dot mark with high accuracy and high image quality. Therefore, it is possible to improve the detection accuracy of the corresponding position and the accuracy of correcting the teaching data.

In the correction system according to one aspect of the present invention, the controller operates the first mounting section in the first direction toward the workpiece according to the teaching data when the robot gun is positioned at the teaching position. , the dot mark may be imaged by the camera in a state of being close to the work.

According to the above aspect, it is possible to capture an image that expresses the relative position of the dot mark with high accuracy and high image quality by the camera, and it is possible to improve the accuracy of correcting the teaching data.

In the correction system according to one aspect of the present invention, an electrode for welding can be attached to and detached from the first attachment portion and the second attachment portion, and the fixture replaces the electrode with the first attachment. may be attached to the part.

According to the above aspect, since the camera is attached to the first mounting portion instead of the electrode, the camera can image the portion of the workpiece that is in contact with the electrode. Such a camera can take an image that expresses the relative position of the dot mark corresponding to the portion in contact with the electrode with high accuracy and high image quality.

In the correction system according to one aspect of the present invention, an electrode for welding can be attached to and detached from the first attachment portion and the second attachment portion, and the fixture attaches the electrode to the first attachment portion. It may be configured such that it can be attached to the first attachment part in an attached state.

According to the above configuration, for example, the camera can capture an image of a state in which the first mounting section is moved in the first direction and the electrode is in contact with the work. Since such an image shows the actual spotting position of the electrode and the spotting mark together, it is possible to detect the relative position between the spotting position and the spotting mark with high precision and ease.

In the correction system according to one aspect of the present invention, the length by which the mounting fixture and the camera attached to the first mounting portion protrude from the first mounting portion in the first direction is The attached electrode may have a length equal to or less than that protruding in the first direction from the first attachment portion.

According to the above aspect, when the first mounting part is moved in the first direction according to the teaching data, the camera and the fixture approach the work to the same extent or less than the electrode, but the camera and the fixture are pressed against the work and damaged. is suppressed.

In the correction system according to an aspect of the present invention, the fixture may offset the direction of the optical axis of the camera so that the direction of the optical axis of the camera intersects the first direction. .

According to the above aspect, the length occupied by the camera in the first direction can be reduced. Therefore, it is possible to save space for attaching the camera to the first mounting portion.

In the correction system according to an aspect of the present invention, the fixture may offset the direction of the optical axis of the camera such that the direction of the optical axis of the camera is parallel to the first direction.

According to the above aspect, the distortion of the dot mark imaged by the camera is suppressed. Therefore, image processing for detecting dot marks can be simplified.

In the correction system according to one aspect of the present invention, the taught position includes a three-dimensional position and orientation of the robot gun at the taught position, and the corresponding position is a three-dimensional position of the robot gun at the corresponding position. and attitude, and the controller corrects the teaching data based on the difference between the three-dimensional position and attitude of the robot gun at the corresponding position and the three-dimensional position and attitude of the robot gun at the teaching position. You may

According to the above aspect, the accuracy of correction of teaching data is improved.

In the correction system according to an aspect of the present invention, the control device may move the robot gun so as to press the second mounting section against the workpiece at the teaching position before imaging with the camera. .

According to the above aspect, the position of the work between the first mounting portion and the second mounting portion is maintained constant. Therefore, detection processing of the positions of the workpiece and the dot mark in the direction from the first mounting portion to the second mounting portion can be simplified.

In the correction system according to an aspect of the present invention, the dot mark may be a marking including a center display portion indicating a center and an orientation display portion indicating a direction in rotation around the center.

According to the above aspect, it is possible to detect the three-dimensional position and orientation of the robot gun as the corresponding position of the robot gun with respect to the dot mark. Correction of teaching data using such corresponding positions enables highly accurate correction.

A robot system according to one aspect of the present invention includes the correction system according to one aspect of the present invention and the robot, and the controller controls the operation of the robot. According to the above aspect, the same effect as that of the correction system according to one aspect of the present invention can be obtained.

A correction method according to an aspect of the present invention is a correction method for correcting teaching data of a robot, wherein a workpiece between a first mounting section and a second mounting section facing each other of a robot gun of the robot is corrected in accordance with the teaching data. moving the robot gun to a teaching position for pressing the first mounting part against a predetermined hitting position; capturing an image of the dot mark attached to the predetermined dot position; detecting the position of the dot mark using the image captured by the camera; and attaching the first mounting portion to the dot mark. detecting a corresponding position that is the position of the robot gun for pressing; and correcting the teaching data based on a difference between the corresponding position and the teaching position, wherein the camera detects the light of the camera. Mounted on the first mounting such that the orientation of the axis is offset from the first mounting that is operable in a first direction. According to the above aspect, the same effect as that of the correction system according to one aspect of the present invention can be obtained.

A correction method according to an aspect of the present invention further includes operating the first mounting section in the first direction toward the workpiece according to the teaching data when the robot gun is positioned at the teaching position, The imaging of the dot mark by the camera may be performed while the camera is close to the workpiece.

In the correction method according to an aspect of the present invention, electrodes for welding can be attached to and detached from the first attachment portion and the second attachment portion, and the camera is attached to the first attachment portion instead of the electrodes. may be attached to the

In the correction method according to an aspect of the present invention, an electrode for welding can be attached to and detached from the first attachment portion and the second attachment portion, and the camera has the electrode attached to the first attachment portion. It may be configured such that it can be attached to the first attachment part in a state where it is attached.

In the correction method according to an aspect of the present invention, the length by which the camera attached to the first mounting portion protrudes from the first mounting portion in the first direction is The length of the electrode protruding in the first direction from the first mounting portion may be less than or equal to that.

In the correction method according to an aspect of the present invention, the direction of the optical axis of the camera may be offset such that the direction of the optical axis of the camera intersects the first direction.

In the correction method according to an aspect of the present invention, the direction of the optical axis of the camera may be offset such that the direction of the optical axis of the camera is parallel to the first direction.

In the correction method according to one aspect of the present invention, the teaching data is corrected based on the difference between the three-dimensional position and orientation of the robot gun at the corresponding position and the three-dimensional position and orientation of the robot gun at the teaching position. The teaching position may include the three-dimensional position and orientation of the robot gun at the teaching position, and the corresponding position may include the three-dimensional position and orientation of the robot gun at the corresponding position.

The correction method according to an aspect of the present invention may further include moving the robot gun so as to press the second mounting section against the workpiece at the teaching position before imaging with the camera.

In the correction method according to an aspect of the present invention, the dot mark may be a marking including a center display portion indicating a center and an orientation display portion indicating a direction in rotation around the center.

A control device according to one aspect of the present invention is a control device that executes the correction method according to one aspect of the present invention. According to the above aspect, the same effect as the correction method according to one aspect of the present invention can be obtained.

(Embodiment)
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the embodiments described below are all comprehensive or specific examples. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in independent claims representing the highest concept will be described as optional constituent elements. Also, each figure in the accompanying drawings is a schematic diagram and is not necessarily strictly illustrated. Furthermore, in each drawing, substantially the same components are denoted by the same reference numerals, and redundant description may be omitted or simplified. Also, in the specification and claims, "device" may mean not only one device, but also a system of multiple devices.

[Configuration of robot system]
A configuration of a robot system 1 according to an embodiment will be described. FIG. 1 is a schematic diagram showing an example of a robot system 1 according to an embodiment. As shown in FIG. 1, the robot system 1 according to the embodiment includes a robot 10, a robot control device 20, an image processing device 30, an input device 40, and an imaging device 50. The robot control device 20 , the image processing device 30 and the imaging device 50 constitute a teaching data correction system 2 . The robot control device 20 and the image processing device 30 constitute the control device 3 .

The robot system 1 can cause the robot 10 to automatically operate and perform a predetermined work according to the instructed operation procedure. The robot system 1 can manually operate the robot 10 according to the operation information input via the input device 40 to perform the work. The robot system 1 can execute a process of automatically correcting teaching data, which is data of a taught operation procedure. The robot system 1 operates by selecting any one of an automatic operation mode in which the robot 10 automatically operates, a manual operation mode in which the robot 10 operates manually, and a correction mode in which teaching data is automatically corrected. In this embodiment, the work performed by the robot 10 is welding work, for example, spot welding work. The work performed by the robot 10 may be welding work other than spot welding, or may be work other than welding work. Such work may be, for example, work involving positioning a movable portion of the robot 10 with respect to an object, such as drilling, screw fastening, sealing, and the like.

The robot 10 as described above is an industrial robot. The robot 10 includes an end effector 11 that actually welds a welding point of a welding object W, which is an example of a workpiece, and a robot arm 12 that moves the end effector 11 to the welding point. For example, the end effector 11 is a welding gun, which is an example of a robot gun. Hereinafter, the "end effector 11" is also referred to as the "welding gun 11". The objects W to be welded are, for example, two thin plate-like objects stacked on top of each other.

The configuration of the robot arm 12 is not particularly limited as long as the position and attitude of the welding gun 11 at the tip can be changed, but in this embodiment, the robot arm 12 is a vertical articulated robot arm. Note that the robot arm 12 may be configured as, for example, a horizontal articulated robot arm, a polar coordinate robot arm, a cylindrical coordinate robot arm, a rectangular coordinate robot arm, or any other robot arm.

The robot arm 12 is fixedly arranged on an installation surface such as a floor surface, but may be arranged on a transport vehicle or the like so as to be movable. The robot arm 12 includes links 12a to 12f arranged in order from its base to its tip, joints JT1 to JT6 that sequentially connect the links 12a to 12f, and arm drive devices M1 to M1 to rotatably drive the joints JT1 to JT6, respectively. M6. A robot controller 20 controls the operations of the arm driving devices M1 to M6. Each of the arm driving devices M1 to M6 is powered by electric power and has a servo motor as an electric motor for driving them, but is not limited to this. The number of joints of the robot arm 12 is not limited to six, and may be seven or more, or may be one or more and five or less.

The joint JT1 connects the installation surface of the robot arm 12 and the base end of the link 12a so as to be rotatable about a vertical axis perpendicular to the installation surface. The joint JT2 connects the distal end of the link 12a and the proximal end of the link 12b so as to be rotatable about a horizontal axis parallel to the installation surface. The joint JT3 connects the distal end of the link 12b and the proximal end of the link 12c so as to be rotatable around the horizontal axis. The joint JT4 connects the distal end of the link 12c and the proximal end of the link 12d so as to be rotatable about the longitudinal axis of the link 12c. The joint JT5 connects the distal end of the link 12d and the proximal end of the link 12e so as to be rotatable about an axis perpendicular to the longitudinal direction of the link 12d. The joint JT6 connects the distal end of the link 12e and the proximal end of the link 12f so as to be torsionally rotatable with respect to the link 12e. A tip of the link 12f constitutes a mechanical interface and is connected to the welding gun 11. As shown in FIG.

FIG. 2 is a side view showing an example of the configuration of welding gun 11 according to the embodiment. FIG. 3 is a side view showing an example of a configuration in which an imaging device 50 is attached in place of the electrode tip 11d in the welding gun 11 of FIG. 2. As shown in FIG. As shown in FIGS. 2 and 3, the welding gun 11 is detachably attached to the tip of the link 12f. The welding gun 11 includes a mounting portion 11a, a body portion 11b, and a moving device 11c. The attachment portion 11a is configured to be connected to the mechanical interface of the link 12f and supports the body portion 11b. The body portion 11b is composed of a U-shaped member and is connected to the mounting portion 11a. In the present embodiment, the body portion 11b is made of the same material as the attachment portion 11a and is integrated with the attachment portion 11a. The body portion 11b is connected to the attachment portion 11a in the vicinity of the end portion 11ba of the U-shaped end portions 11ba and 11bb. The main body portion 11b has a movable first mounting portion 11bc at the end portion 11ba and a second mounting portion 11bd fixed to the main body portion 11b at the end portion 11bb. The mounting portions 11bc and 11bd are arranged to face each other in the direction D1, and the first mounting portion 11bc is movable in the direction D1 toward the second mounting portion 11bd and the direction D2 away from the second mounting portion 11bd. Directions D1 and D2 are opposite to each other. Direction D1 is an example of a first direction.

The moving device 11c is arranged at the end portion 11ba and moves the first mounting portion 11bc in the directions D1 and D2. The movement device 11c includes a movement drive device 11ca and a movement drive mechanism 11cb. The movement driving device 11ca drives the movement driving mechanism 11cb. The movement drive device 11ca uses electric power as a power source and has a servo motor as an electric motor, but is not limited to this. The operation of the movement drive device 11ca is controlled by the robot controller 20. FIG.

The movement driving mechanism 11cb transmits the driving force of the movement driving device 11ca to the first mounting portion 11bc to move the first mounting portion 11bc in the directions D1 and D2. The movement driving mechanism 11cb converts the rotational driving force of the movement driving device 11ca into a linear driving force and transmits the linear driving force to the first mounting portion 11bc. The movement driving mechanism 11cb has, for example, a ball screw structure, and the rod-like screw connected to the first mounting portion 11bc is rotated in the axial directions D1 and D2 by rotating the nut by the movement driving device 11ca. move to The movement driving device 11ca is not limited to an electric motor, and may be, for example, a hydraulic or pneumatic piston, an electric linear actuator, or the like. The movement driving device 11ca and the movement driving mechanism 11cb may be configured to move the first mounting portion 11bc in the directions D1 and D2.

The second mounting portion 11bd is configured such that an electrode tip 11d, which is an example of an electrode for welding, is detachable. For example, the electrode tip 11d may be configured to be attached by being inserted into a hole of the second attachment portion 11bd. In the present embodiment, the electrode tip 11d has a cylindrical shape with a hemispherical tip, but is not limited to this. The welding gun 11 includes a contact sensor 11e that detects contact between the electrode tip 11d attached to the second attachment portion 11bd and the object W to be welded. The contact sensor 11 e transmits a detection signal indicating contact between the electrode tip 11 d and the object W to be welded to the robot controller 20 . The configuration of the contact sensor 11e is not particularly limited as long as it can detect the above contact. It is configured to transmit a signal representing a change in current at the time of contact with the object W as a detection signal.

The first mounting portion 11bc is configured such that the electrode tip 11d is detachable. Further, the first mounting portion 11bc is configured so that the imaging device 50 can be attached and detached instead of the electrode tip 11d. The electrode tip 11d and the imaging device 50 can be replaced with each other and attached to the first attachment portion 11bc. For example, the electrode tip 11d and the imaging device 50 may be configured to be attached by being inserted into a hole of the first attachment portion 11bc.

The imaging device 50 has a camera 51 and a fixture 52 . The camera 51 is a small camera that captures digital images. Examples of the camera 51 are image sensors such as CMOS (Complementary Metal-Oxide Semiconductor) image sensors and CCD (Charge Coupled Device) image sensors. The camera 51 is controlled for operation by the robot control device 20 and transmits signals of captured images to the robot control device 20 and/or the image processing device 30 . Although the camera 51 is a monocular camera in this embodiment, it is not limited to this. For example, the camera 51 is a compound eye camera, a TOF camera (Time-of-Flight-Camera), a pattern light projection camera such as fringe projection, or a camera using a light section method, etc., for detecting the position of the subject. You may have the structure which images the image of.

The fixture 52 attaches the camera 51 to the first mounting portion 11bc. The fixture 52 holds the camera 51 and is configured to be detachably attached to the first attachment portion 11bc. The fixture 52 attaches the camera 51 to the first mounting portion 11bc so that the direction of the optical axis 51a of the camera 51 is offset from the first mounting portion 11bc by being mounted to the first mounting portion 11bc. In this embodiment, the fixture 52 offsets the direction of the optical axis 51a of the camera 51 from the first mounting portion 11bc so that the direction of the optical axis 51a of the camera 51 intersects the direction D1. attaches the camera 51 to the first mounting portion 11bc with the optical axis 51a offset from the motion path of the first mounting portion 11bc in the directions D1 and D2. The direction of the optical axis 51a of the camera 51 and the direction D1 intersect obliquely. In the present embodiment, the axis 11da of the electrode tip 11d attached to the first attachment portion 11bc and the optical axis 51a of the camera 51 attached to the first attachment portion 11bc via the fixture 52 intersect. may be in a twisted relationship without intersecting. The axis 11da of the electrode tip 11d attached to the first attachment portion 11bc is coaxial with the axis of the electrode tip 11d attached to the second attachment portion 11bd. The axis 11da is also the axis of the first mounting portion 11bc.

The fixture 52 integrally includes a cylindrical connecting portion 52a connected to the first mounting portion 11bc, and a cylindrical accommodating portion 52b extending from the connecting portion 52a. The accommodation portion 52b accommodates and holds the camera 51 and its harness, etc., and exposes the lens of the camera 51 at the end connected to the connection portion 52a. The axis of the connection portion 52a connected to the first attachment portion 11bc is coaxial with the axis 11da of the electrode tip 11d attached to the first attachment portion 11bc, but is not limited to this. The axis of the housing portion 52b is coaxial with the optical axis 51a of the camera 51, but is not limited to this. The accommodation portion 52b attached to the first attachment portion 11bc extends from the connection portion 52a in the direction D2 along a direction obliquely crossing the direction of the axis of the connection portion 52a. The accommodating portion 52b is arranged so as to prevent interference with the main body portion 11b of the welding gun 11 and the moving device 11c, while suppressing the amount of protrusion from the connecting portion 52a in the direction D1, or so as not to protrude from the connecting portion 52a. can

Such a fixture 52 can reduce the length of projection in the direction D1 from the first mounting portion 11bc when mounted on the first mounting portion 11bc. In the present embodiment, the length by which the fixture 52 and the camera 51 protrude from the first mounting portion 11bc in the direction D1 when attached to the first mounting portion 11bc is It is equal to or less than the length protruding in the direction D1. As a result, the fixture 52 and the camera 51 attached to the first attachment portion 11bc are connected to the first attachment portion 11bc and the second attachment portion even when the first attachment portion 11bc is moved in the direction D1 for the welding operation. 11bd, and is suppressed from being strongly pressed against the object W to be welded and damaged.

The input device 40 receives commands, information, data, and the like input by the user of the robot system 1 and outputs the commands, information, data, and the like to the robot control device 20 . The input device 40 is connected to the robot control device 20 via wired communication or wireless communication. Wired communication and wireless communication may be in any form. For example, the input device 40 receives input of a command to execute any one of the automatic operation mode, the manual operation mode, and the correction mode, and outputs the command to the robot control device 20 . The input device 40 may include a teaching device such as a teaching pendant for teaching the robot 10 the operation procedure of a predetermined welding operation.

The robot controller 20 controls the robot system 1 as a whole. For example, robot controller 20 may include a computing device.

The image processing device 30 generates image data from the image signal received from the camera 51 and performs image processing on the image data. For example, image processing device 30 may include a computing device. The image processing device 30 performs image processing to detect the three-dimensional position and orientation of the subject appearing in the image data. A 3D position is a position in a 3D space. For example, the camera 51 captures an image of a dot mark placed at a predetermined dot position on the surface of the object W to be welded, and the image processing device 30 detects the three-dimensional position and orientation of the dot mark appearing in the image data. The predetermined welding point position is the position to be welded when the robot 10 performs the welding work according to the teaching data in the automatic operation mode, and is the position to which the electrode tip 11d of the welding gun 11 should be pressed. Examples of the dot marks are spot welding traces on the surface of the object W to be welded, and markings including graphics. If the dot mark does not have directionality, only the three-dimensional position of the dot mark may be detected.

For example, in the correction mode, when the robot 10 performs the same operation as welding by automatic operation according to the teaching data, the position of the actual welding point, which is the position where the robot 10 actually welds, and the position where the robot 10 should originally weld The teaching data is corrected so as to reduce the difference from the predetermined hitting position. A dot mark is attached to such a predetermined dot position, and the dot mark may be marked on the surface of the object to be welded W by marking a position positioned by calculation or the like. The welding mark may be made on the surface of the object W to be welded by causing the robot 10 to actually perform the welding operation.

[Hardware configuration of robot system]
A hardware configuration of the robot system 1 will be described. FIG. 4 is a block diagram showing an example of the hardware configuration of the robot system 1 according to the embodiment. As shown in FIG. 4, the robot control device 20 includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, a memory 204, an input/output I/F ( Interfaces 205 to 207, an arm drive circuit 208, and a gun drive circuit 209 are included as components. Each of the above components are connected via a bus, wired communication or wireless communication. Note that not all of the above components are essential.

For example, the CPU 201 is a processor and controls the overall operation of the robot controller 20 . A ROM 202 is composed of a non-volatile semiconductor memory or the like, and stores programs, data, and the like for causing the CPU 201 to control operations. A RAM 203 is composed of a volatile semiconductor memory or the like, and temporarily stores a program to be executed by the CPU 201 and data that is being processed or has been processed. The memory 204 is configured by a storage device such as a semiconductor memory such as a volatile memory and a nonvolatile memory, a hard disk (HDD: Hard Disc Drive) and an SSD (Solid State Drive), and stores various information. Memory 204 may be a device external to robot controller 20 .

For example, a program for operating the CPU 201 is pre-stored in the ROM 202 or the memory 204 . The CPU 201 reads a program from the ROM 202 or the memory 204 to the RAM 203 and expands it. The CPU 201 executes each coded instruction in the program developed in the RAM 203 .

Each function of the robot control device 20 may be realized by a computer system consisting of the CPU 201, ROM 202, RAM 203, etc., or may be realized by a dedicated hardware circuit such as an electronic circuit or an integrated circuit. It may be realized by a combination of hardware circuits.

The first input/output I/F 205 is connected to the input device 40 and inputs/outputs information, data, commands, and the like to/from the input device 40 . The first input/output I/F 205 may include a circuit for converting signals. A second input/output I/F 206 is connected to the image processing apparatus 30 and inputs/outputs information, data, commands, and the like to/from the image processing apparatus 30 . The second input/output I/F 206 may include a circuit for converting signals. The third input/output I/F 207 is connected to the camera 51 and inputs/outputs information, data, commands, and the like to/from the camera 51 . The third input/output I/F 207 may include a circuit or the like for driving the camera 51 .

The arm driving circuit 208 supplies power to the servo motors of the arm driving devices M1 to MA6 of the robot 10 according to instructions from the CPU 201, and controls the driving of the servo motors. The gun drive circuit 209 supplies power to the servomotor of the movement drive device 11ca of the welding gun 11 according to instructions from the CPU 201 and controls the drive of the servomotor.

The image processing apparatus 30 includes a CPU 301, a ROM 302, a RAM 303, a memory 304, and input/output I/Fs 305-306 as components. Each of the above components are connected via a bus, wired communication or wireless communication. Note that not all of the above components are essential. Configurations of the CPU 301 , ROM 302 , RAM 303 and memory 304 are the same as those of the robot control device 20 . The first input/output I/F 305 is connected to the robot control device 20 and inputs/outputs information, data, commands, etc. to/from the robot control device 20 . A second input/output I/F 306 is connected to the camera 51 and inputs/outputs information, data, commands, and the like to/from the camera 51 . For example, the second input/output I/F 306 receives signals of images captured by the camera 51 . The input/output I/Fs 305 to 306 may include circuits for converting signals.

The robot control device 20 and the image processing device 30 as described above are, for example, microcontrollers, MPUs (Micro Processing Units), LSIs (Large Scale Integration), system LSIs, PLCs (Programmable Logic Controllers), logic It may be configured by a circuit or the like. A plurality of functions of the robot control device 20 may be realized by being individually integrated into one chip, or may be implemented by being integrated into one chip so as to include some or all of them. Further, each circuit may be a general-purpose circuit or a dedicated circuit. As an LSI, an FPGA (Field Programmable Gate Array) that can be programmed after the LSI is manufactured, a reconfigurable processor that can reconfigure the connections and/or settings of the circuit cells inside the LSI, or multiple functions for specific purposes. ASIC (Application Specific Integrated Circuit) or the like in which the circuits are integrated into one may be used.

[Functional Configuration of Robot System]
A functional configuration of the robot system 1 will be described. FIG. 5 is a block diagram showing an example of the functional configuration of the robot system 1 according to the embodiment. As shown in FIG. 5, the robot control device 20 includes an imaging control unit 20a, a mode determination unit 20b, a manual command generation unit 20c, an automatic command generation unit 20d, an operation control unit 20e, a correction unit 20f, A storage unit 20g is included as a functional component. The motion control section 20e includes an arm control section 20ea and a gun control section 20eb. Not all of the above functional building blocks are essential. The functions of functional components other than the storage unit 20g are implemented by the CPU 201 and the like, and the functions of the storage unit 20g are implemented by the memory 204, ROM202 and/or RAM203.

The storage unit 20g stores various information and enables reading of the stored information. For example, the storage unit 20g stores a program that causes the robot control device 20 to operate. Further, the storage unit 20g stores teaching data 20ga stored by teaching for causing the robot 10 to perform a predetermined welding operation.

In this embodiment, the teaching method of the robot 10 is teaching by programming, and the teaching data 20ga is off-line teaching data. The teaching method of the robot 10 may be, for example, direct teaching by a teacher directly touching and moving the robot 10, teaching by remote control using a teaching pendant, or teaching by a master-slave. In the welding operation of the robot 10 according to off-line teaching data, due to factors such as individual differences in the operation of the robot 10, the actually welded position may not match the original position to be welded. In the welding operation of the robot 10 according to the teaching data taught by the teacher, the position actually welded may not match the position to be originally welded due to factors such as the difference in skill level of the teacher. Therefore, it is necessary to correct the teaching data 20ga.

The teaching data 20ga includes the gun teaching position set as the position of the welding gun 11 for welding at each welding position included in the welding work, and the electrode teaching set as the position of the first mounting portion 11bc during welding. including location, etc. For example, the welding position is the position of the welding point against which the electrode tip 11d is pressed on the object to be welded. The gun teaching position may include the three-dimensional position and orientation of welding gun 11 . The electrode teaching position is the relative position of the first mounting portion 11bc with respect to the welding gun 11, and may be the amount of movement of the first mounting portion 11bc. The teaching data 20ga may include the time at each gun teaching position and the time at each electrode teaching position. Further, the teaching data 20ga may include the force applied by the welding gun 11 to the object to be welded at each gun teaching position, and may include the force applied by the first mounting portion 11bc to the object to be welded via the electrode tip 11d.

The storage unit 20g may also store the relationship between the three-dimensional position and orientation of the welding point and the three-dimensional position and orientation of the welding gun 11 for welding to the welding point. The three-dimensional position of the hit point may be the three-dimensional position of the center of the hit point. The orientation of the hitting point is not particularly limited, but may include, for example, the amount and direction of inclination of the surface formed by the hitting point with respect to the vertical axis, the horizontal orientation of a specific point on the hitting point with respect to the center of the hitting point, and the orientation of the hitting point. It may be the three-dimensional orientation of a specific point on the hit point with respect to the center.

The storage unit 20g also stores information on the welding gun 11, the electrode tip 11d, the object to be welded, and the imaging device 50. FIG. The information of the welding gun 11 includes the distance between the first mounting portion 11bc retreated to the end portion 11ba of the welding gun 11 and the second mounting portion 11bd, the movable amount of the first mounting portion 11bc, and the like. The information on the electrode tip 11d includes dimensions such as the length of the electrode tip 11d attached to the first attachment portion 11bc and the second attachment portion 11bd. The information on the object to be welded includes the type, material, and dimensions such as thickness of the object to be welded. Information on the imaging device 50 includes information on the camera 51 and the fixture 52 . The information of the camera 51 includes camera parameters of the camera 51 , and the camera parameters include internal parameters regarding the camera 51 itself and external parameters regarding the surrounding environment of the camera 51 . The information on the fixture 52 may include information on the positional relationship between the connecting portion 52a and the receiving portion 52b, such as the angle between the axis of the connecting portion 52a and the axis of the receiving portion 52b and the distance between them. Each of the above information may be stored in the storage unit 20g by input through the input device 40. FIG.

The imaging control unit 20 a controls the imaging operation of the camera 51 . For example, the image pickup control unit 20a operates in the correction mode, and directs the camera 51 of the image pickup device 50 attached to the first attachment portion 11bc of the welding gun 11 to the welding object with the welding mark at the welding point position. Take pictures in time. In this embodiment, in the correction mode, the robot 10 performs the same operation as welding work according to the teaching data 20ga. The object to be welded is positioned between the first mounting portion 11bc and the second mounting portion 11bd of the welding gun 11 . When the welding gun 11 is positioned at the gun teaching position for pressing the first mounting portion 11bc against the predetermined welding point position of the object to be welded according to the teaching data 20ga, the imaging control unit 20a controls the welding mark attached to the predetermined welding point position. is imaged by the camera 51 . Specifically, when the welding gun 11 is positioned at the gun teaching position, the first mounting portion 11bc is operated in the direction D1 so as to press the electrode tip 11d against the welding object in accordance with the teaching data 20ga and approaches the welding object. , the imaging control unit 20a causes the camera 51 to image the dot mark. The timing may be the timing when the camera 51 comes closest to the object to be welded. It may be a predetermined timing during movement of the mounting portion 11bc. Note that the image processing device 30 may include the imaging control section 20a.

The mode determination unit 20b determines the mode to be executed by the robot system 1 from among the automatic operation mode, the manual operation mode, and the correction mode according to a command specifying a mode via the input device 40, and determines other functional components. Operate according to the determined mode.

The manual command generation unit 20c generates a motion command for causing the robot 10 to perform a motion corresponding to the operation information output from the input device 40 in the manual operation mode or during execution of teaching by the teacher, and the motion control unit 20e. output to

In the automatic operation mode and the correction mode, the automatic command generation unit 20d generates an operation command for automatically causing the robot 10 to perform a predetermined welding work according to the teaching data 20ga, and outputs the operation command to the operation control unit 20e. The automatic command generation unit 20d acquires information on the welding work via the input device 40, reads the teaching data 20ga corresponding to the welding work from the storage unit 20g, and uses it. For example, in the automatic operation mode, the automatic command generation unit 20d generates an operation command to pressurize the welding object by pressing the electrode tip 11d of the first mounting part 11bc against the welding object. An operation command is generated to cause the imaging device 50 of the first mounting portion 11bc to approach and contact but not pressurize or contact.

The operation command includes commands such as the three-dimensional position and posture of the welding gun 11, the position of the first mounting portion 11bc with respect to the welding gun 11, and the time at each position. The operation command may include commands such as the force applied by the welding gun 11 to the object to be welded at each position and the force applied by the first mounting portion 11bc to the object to be welded via the electrode tip 11d.

The motion control section 20e controls the motion of the robot 10 according to the motion command. The arm control unit 20ea of the motion control unit 20e generates a command for operating the servo motors of the arm driving devices M1 to M6 of the robot arm 12 so that the three-dimensional position and orientation of the welding gun 11 follow the motion command. and output to the arm driving devices M1 to M6. The arm control unit 20ea acquires the amount of rotation and the drive current of each of the servo motors of the arm drive devices M1 to M6 as feedback information, and uses it to generate the command. The gun control unit 20eb generates a command for operating the servo motor of the moving drive device 11ca of the welding gun 11 so that the position of the first mounting part 11bc follows the operation command, and outputs the command to the moving drive device 11ca. . The gun control unit 20eb acquires the amount of rotation and the drive current of the servomotor of the movement drive device 11ca as feedback information, and uses it to generate the command.

The correction section 20f operates in a correction mode and corrects the teaching data 20ga. The correction unit 20 f receives from the image processing device 30 the three-dimensional position and orientation of the dot marks on the surface of the object to be welded detected from the image captured by the camera 51 . Further, the correction unit 20f actually presses the electrode tip 11d of the first mounting part 11bc of the welding gun 11 against the center of the dot mark based on the three-dimensional position and orientation of the dot mark. A corresponding position, which is the position of the welding gun 11 for performing welding, is detected. The corresponding position includes the three-dimensional position and orientation of the welding gun 11, but may include only the three-dimensional position of the welding gun 11 when the orientation of the welding gun 11 is constant, for example. For example, the correction unit 20f detects the corresponding position based on the relationship between the three-dimensional position and orientation of the welding point stored in the storage unit 20g and the three-dimensional position and orientation of the welding gun 11 for welding to the welding point. good too.

moreover. The correction unit 20f adjusts the corresponding position of the welding gun 11 for actually performing welding at the center of the spot mark and the gun teaching position of the welding gun 11 set for performing welding at the center of the spot mark. Based on the difference, the teaching data 20ga is corrected. The correction unit 20f may correct the gun teaching position so as to reduce the difference, and may correct the gun teaching position by, for example, replacing it with a corresponding position.

The image processing device 30 includes an extraction unit 30a, a mark position detection unit 30b, and a storage unit 30c as functional components. Not all of the above functional building blocks are essential. The functions of the extraction unit 30a and the mark position detection unit 30b are implemented by the CPU 301 and the like, and the functions of the storage unit 30c are implemented by the memory 304, ROM302 and/or RAM303.

The storage unit 30c stores various information and enables reading of the stored information. For example, the storage unit 30c stores a program that causes the image processing device 30 to operate. Further, the storage unit 30c stores information on the dot marks. When the spot welding mark is a spot welding mark, the information of the spot welding mark may include information on the shape, size, color and texture of the spot welding mark, image data of the spot welding mark, and the like. When the dot mark is a marking, the information of the dot mark may include image data of the marking, and information on the shape, size, and arrangement of the marking and figures constituting the marking.

In this embodiment, the marking of the dot mark has directionality. For example, as shown in FIG. 6, the marking is composed of a plurality of figures, and the plurality of figures represent the center of the marking and the orientation of the marking. FIG. 6 is a diagram showing an example of marking of the dot mark according to the embodiment. The marking M in FIG. 6 is composed of an outer circle Ma, an equilateral triangle Mb inscribed in the outer circle Ma, an inner circle Mc inside the equilateral triangle Mb, and a point Md near the inside of one corner of the equilateral triangle Mb. Configured. The inner peripheral circle Mc represents the center of the marking M and is an example of the center indicator. An equilateral triangle Mb and a point Md represent the orientation of the marking M, and are an example of the directional indicator.

Further, as the image data of the dot mark, not only front image data, which is image data taken from the front of the dot mark, but also oblique image data, which is image data taken from various angles with respect to the dot mark, It may be stored in the storage unit 30c. In the oblique direction image data, the dot mark is represented distorted.

In addition, the storage unit 30c may store information on the welding gun 11, the electrode tip 11d, the object to be welded W, and the imaging device 50. FIG. These pieces of information may be transmitted from the robot control device 20 to the image processing device 30 and stored in the storage unit 30c.

The extraction unit 30a detects the dot mark from the subject appearing in the image data captured by the camera 51 in the correction mode.

For example, if the dot mark is a spot welding mark, the extraction unit 30a executes binary conversion or the like on the image data to detect edges. The extraction unit 30a compares the image data before conversion and the image data after conversion with the image data of the spot welding marks, and performs shape pattern matching, color pattern matching, and/or texture pattern matching. , to detect the image of the spot weld marks. The extractor 30a extracts the axial center 11da of the electrode tip 11d at the first mounting portion 11bc and the camera 51 based on information such as the angle between the axial center of the connection portion 52a of the fixture 52 and the axial center of the housing portion 52b. and the optical axis 51a, and based on the detection result, the distortion of the subject in the image data captured obliquely may be corrected. The extraction unit 30a may detect the image of the spot welding mark using the image data after the distortion correction.

For example, if the dot mark is a marking, the extraction unit 30a executes binary conversion or the like on the image data to detect edges. The extraction unit 30a compares the image data after conversion with the image data of the marking, and executes shape pattern matching to detect the image of the marking. Alternatively, the extraction unit 30a detects line segments and arcs by executing Hough transform or the like on the converted image data. Further, the extraction unit 30a detects a figure included in the marking and a figure similar to the figure in the image data after the Hough transform, and selects a combination forming the marking from among the combinations of the detected figures as an image of the marking. Detect as A combination of graphics includes the shape and arrangement of graphics. The extracting unit 30a detects a similar figure so as to consider the distortion of the object in the image data captured from an oblique direction. For example, for the marking M of FIG. 6, the extraction portion 30a includes the outermost circle or ellipse, its inner triangle, the inner circle or ellipse of the triangle, and the inner point of one corner of the triangle. Detect combinations. Note that the extraction unit 30a may correct the distortion of the object in the image data captured from an oblique direction, and detect the marking using the image data after the distortion correction.

The mark position detection unit 30b detects the three-dimensional position and orientation of the dot mark using the image data captured by the camera 51 and the information of the dot mark detected in the image data. The mark position detection unit 30b also uses information on the welding gun 11, the electrode tip 11d, the welding object W, and the fixture 52 of the imaging device 50 for the above detection. The operation of the mark position detection unit 30b will be described using the case of marking M as an example.

FIG. 7 is a side view showing an example of a state in which the camera 51 captures an image of the dot mark in the correction mode. FIG. 8 is a diagram showing an example of an image captured by the camera 51 in the state of FIG. As shown in FIG. 8, the mark position detection unit 30b detects the center of the marking M, that is, the pixel coordinates of the pixel pMc at the center of the inner circumference Mc, and the center of the circular point Md. , and the pixel coordinates of the pixel pMd. The pixel coordinates are coordinates in units of pixels in the image coordinate system of the image Ia.

The position of the optical axis 51a of the camera 51 is the center pixel pI of the image Ia. Based on the positional relationship between the pixel pMc and the pixel pI, the mark position detection unit 30b detects the included angle α between the line of sight LMc from the camera 51 shown in FIG. The direction of the line of sight LMc is calculated. The intersection point Pd between the axis 11da of the first mounting portion 11bc and the surface of the object W to be welded is the center of the welding point position of the electrode tip 11d of the first mounting portion 11bc when welding is performed according to the teaching data 20ga. .

Further, the mark position detection section 30b calculates the distance da between the tip of the first mounting section 11bc and the surface of the welding target W when the camera 51 captures the image. Specifically, the mark position detection unit 30b acquires feedback information from the gun control unit 20eb of the robot control device 20 during imaging by the camera 51, and detects the position of the first mounting unit 11bc based on the feedback information. The mark position detector 30b calculates the distance da based on the position of the first mounting portion 11bc, the distance between the first mounting portion 11bc and the second mounting portion 11bd, and the thickness of the welding target W.

The mark position detection unit 30b detects the inner peripheral circle Mc based on the projection length of the fixture 52 from the first mounting portion 11bc in the direction D1, the orientation and included angle α of the line of sight LMc with respect to the optical axis 51a, and the distance da. Calculate the three-dimensional position of the center. The mark position detection unit 30b may acquire the protrusion length from the storage unit 20g of the robot control device 20, or may acquire the protrusion length previously stored in the storage unit 30c.

Furthermore, the mark position detection unit 30b calculates the three-dimensional position of the center of the point Md in the same manner as the calculation of the three-dimensional position of the center of the inner peripheral circle Mc. The mark position detection unit 30b calculates the three-dimensional position of the center of the marking M and the orientation of the marking M in the three-dimensional space based on the three-dimensional positions of the center of the inner circumferential circle Mc and the center of the point Md. The orientation of the marking M may be any orientation, but may be, for example, an orientation, which is the horizontal orientation of the center of the point Md with respect to the center of the marking M, and the three-dimensional orientation of the point Md with respect to the center of the marking M. It may be the orientation of the direction, or the amount and direction of inclination of the surface formed by the marking M with respect to the vertical axis. The mark position detection unit 30b transmits the three-dimensional position and orientation of the center of the marking M to the correction unit 20f of the robot control device 20. FIG.

The mark position detector 30b also detects the three-dimensional position and posture of the spot welding mark in the same manner as the marking, even when the spot welding mark is the spot welding mark. For example, the mark position detection unit 30b can detect the posture of the spot-welding mark by detecting the three-dimensional position of the center of the spot-welding mark and the three-dimensional position of at least part of the outer periphery of the spot-welding mark. .

[Operation of the robot system]
The operation in the correction mode among the operations of the robot system 1 according to the embodiment will be described. FIG. 9 is a flow chart showing an example of operation in the correction mode of the robot system 1 according to the embodiment.

As shown in FIG. 9, first, in step S1, the user replaces the electrode tip 11d of the first mounting portion 51bc of the welding gun 11 with the imaging device 50. As shown in FIG. That is, the fixture 52 of the imaging device 50 is attached to the first mounting portion 51bc. Next, in step S<b>2 , a command to execute the correction mode is input by the user to the input device 40 and accepted by the robot controller 20 .

Next, in step S3, the robot control device 20 causes the robot 10 to automatically operate according to the teaching data 20ga in the storage section 20g. Next, in step S4, the robot controller 20 causes the robot 10 to move the welding gun 11 to the next welding position among the plurality of welding positions included in the teaching data 20ga.

Next, in step S5, the robot control device 20 causes the robot 10 to adjust the position and orientation of the welding gun 11 with respect to the welding point position. Specifically, the robot control device 20 adjusts the posture of the welding gun 11 so that the axis 11da of the first mounting portion 11bc is perpendicular to the surface of the welding object W at the welding point. Further, the robot control device 20 moves the welding gun 11 with respect to the object W to be welded in the direction D2, thereby bringing the electrode tip 11d of the second attachment portion 11bd into contact with the object W to be welded. The robot control device 20 detects the contact based on the detection signal of the contact sensor 11e.

Next, in step S6, the robot control device 20 causes the moving device 11c of the welding gun 11 to perform the same operation as during welding, that is, the welding operation. Specifically, the robot control device 20 causes the moving device 11c to move the first mounting portion 11bc in the direction D1, bring it closest to the object W to be welded, and then move it in the direction D2 to move it away from the object W to be welded. Let At this time, the robot control device 20 does not press the imaging device 50 against the welding target W as in the automatic operation mode, but brings the imaging device 50 into contact with the welding target W. Do not pressurize or contact

Next, in step S7, the robot control device 20 controls the camera 51 at a predetermined timing in the process in which the first mounting portion 11bc approaches the welding object W or in the process in which the first mounting portion 11bc moves away from the welding object W. to image the surface of the object W to be welded. Note that the robot control device 20 may or may not temporarily stop the first mounting section 11bc during imaging. The camera 51 associates the signal of the picked-up image with information on the hitting position, transmits it to the image processing device 30, and stores it in the storage unit 30c as image data. good.

Next, in step S8, the robot control device 20 determines whether or not the welding operation to all the welding point positions included in the teaching data 20ga has been completed. If completed (Yes in step S8), the robot control device 20 proceeds to step S9, and if not completed (No in step S8), proceeds to step S4.

In step S9, the image processing device 30 detects the dot mark appearing in the image data by processing the image data captured at each dot position. Next, in step S10, the image processing device 30 detects the three-dimensional position and orientation of the dot mark using the image data at each dot position and the information of the dot mark detected in the image data. The image processing device 30 associates the information of each hit position with the three-dimensional position and orientation of the hit mark at that hit position and transmits them to the robot control device 20 .

Next, in step S11, the robot control device 20 detects the corresponding position of the welding gun 11 for actually performing welding at the center of each hitting mark based on the three-dimensional position and orientation of the hitting mark. do. Next, in step S12, the robot control device 20 determines, for each welding point position, the gun teaching position of the welding gun 11 that is set to perform welding at the welding point position, and the correspondence of the welding gun 11 at the welding point position. Based on the difference from the position, the teaching data 20ga is corrected.

Through the processing of steps S1 to S12, the robot system 1 can automatically sequentially image the dot marks corresponding to the respective dot positions and correct the teaching data 20ga.

(Modification)
In the robot system according to the modification, the configuration of an imaging device 50A detachable from the welding gun 11 is different from that of the embodiment. The fixture 52A of the imaging device 50A according to the modification offsets the direction of the optical axis 51a of the camera 51 from the first mounting portion 11bc so that the direction of the optical axis 51a of the camera 51 is parallel to the direction D1. attaches the camera 51 to the first mounting portion 51bc with the optical axis 51a offset from the motion path of the first mounting portion 11bc in directions D1 and D2. In the following, this modified example will be described with a focus on the points that differ from the embodiment, and the description of the points that are the same as the embodiment will be omitted as appropriate.

FIG. 10 is a side view showing an example configuration of an imaging device 50A of a welding gun 11 according to a modification. The imaging device 50A includes a camera 51 and a fixture 52A. The fixture 52A integrally includes a cylindrical connecting portion 52Aa and a cylindrical accommodating portion 52Ab. The axis of the housing portion 52Ab is parallel to the axis of the connecting portion 52a. Therefore, the optical axis 51a of the camera 51 attached to the first attachment portion 11bc via the fixture 52A is parallel to the axial center 11da of the electrode tip 11d attached to the first attachment portion 11bc. Furthermore, in this modified example, the axis of the accommodating portion 52Ab is located apart from the axis of the connection portion 52a in the direction perpendicular to the axis of the connection portion 52a. That is, the optical axis 51a and the axial center 11da are separated. The accommodating portion 52Ab extends in the direction D2 from the connecting portion 52Aa. The accommodating portion 52Ab is arranged so as to prevent interference with the main body portion 11b of the welding gun 11 and the moving device 11c, while suppressing the amount of protrusion from the connecting portion 52Aa in the direction D1, or so as not to protrude from the connecting portion 52Aa. can

The camera 51 mounted on the first mounting portion 11bc via the fixture 52A as described above captures the spot mark on the welding object W in the correction mode, and generates an image of the spot mark with small distortion. can do. This makes it possible to simplify image processing in the image processing device 30 .

In addition, in this modified example, the axis of the accommodating portion 52Ab that is offset from the axis of the connection portion 52a is located away from the axis of the connection portion 52a. It may be coaxial with the axis.

(Other embodiments)
Although examples of embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments and modifications. That is, various modifications and improvements are possible within the scope of the present invention. For example, the scope of the present invention includes various modifications of the embodiments and modifications, and forms constructed by combining components of different embodiments and modifications.

For example, in the embodiment and the modified example, the robot controller 20 causes the robot 10 to move the welding gun 11 to each welding point position according to the teaching data 20ga in the correction mode, Although the camera 51 is caused to take an image by moving toward the object, the present invention is not limited to this. For example, the robot control device 20 causes the robot 10 to move the welding gun 11 to each welding point position according to the teaching data 20ga. good. Alternatively, the robot control device 20 moves the first mounting portion 11bc in the direction D1 toward the object W to be welded, but before the position where the electrode tip 11d contacts the object W, that is, in the direction D2 of the position. After stopping at the side position, it may be pulled back in the direction D2. In this case, the control device 20 may cause the camera 51 to take an image at the position concerned, or may take an image during the movement process.

In addition, in the embodiment and the modified example, the robot control device 20 brings the electrode tip 11d of the second mounting portion 11bd of the welding gun 11 into contact with the object to be welded before executing the imaging by the camera 51 in the correction mode. However, the present invention is not limited to this, and the contact may not be made. In this case, the image processing device 30 may detect the distance between the camera 51 and the object to be welded by processing image data captured by the camera 51 .

In addition, in the embodiment and modification, the attachments 52 and 52A of the imaging devices 50 and 50A are configured to be attached to the first attachment portion 11bc of the welding gun 11 instead of the electrode tip 11d. is not limited to For example, the fixtures 52 and 52A may be configured to be attached to the first attachment portion 11bc at a position different from that of the electrode tip 11d. In this case, the fixtures 52 and 52A may be configured so that they can be attached to the first attachment portion 11bc even when the electrode tip 11d is attached to the first attachment portion 11bc. That is, the fixtures 52 and 52A may be configured to be attached to the first attachment portion 11bc together with the electrode tip 11d. For example, the fixtures 52 and 52A may be attached to the first mounting portion 11bc laterally with respect to the direction D1.

Further, in the embodiment and the modified example, the robot control device 20 and the image processing device 30 are separate devices, but they are not limited to this and may be included in one device. Also, each of the robot control device 20 and the image processing device 30 may be composed of two or more devices.

The present invention may also be a correction method. For example, a correction method according to an aspect of the present invention is a correction method for correcting teaching data of a robot, and is a method of correcting a robot gun of the robot according to the teaching data. moving the robot gun to a teaching position for pressing the first mounting part against a predetermined hitting position of the workpiece; causing a camera to take an image of the dot mark attached to the predetermined dot position; using the image captured by the camera to detect the position of the dot mark; and attaching the first dot mark to the dot mark. detecting a corresponding position, which is the position of the robot gun for pressing the part; and correcting the teaching data based on a difference between the corresponding position and the teaching position, wherein the camera is mounted on the first mounting part such that the direction of the optical axis of is offset from the first mounting part that is operable in a first direction. Such a correction method may be realized by a circuit such as a CPU, an LSI, an IC card, a single module, or the like.

Further, the present invention may be a program or a non-temporary computer-readable recording medium on which the above program is recorded. Needless to say, the above program can be distributed via a transmission medium such as the Internet.

In addition, all numbers such as ordinal numbers and numbers used above are examples for specifically describing the technology of the present invention, and the present invention is not limited to the numbers shown. Moreover, the connection relationship between the components is an example for specifically describing the technology of the present invention, and the connection relationship for realizing the function of the present invention is not limited to this.

Also, the division of blocks in the functional block diagram is an example, and a plurality of blocks may be implemented as one block, one block may be divided into a plurality of blocks, and/or some functions may be moved to other blocks. good. Also, a single piece of hardware or software may process functions of multiple blocks having similar functions in parallel or in a time division manner.

1 robot system 2 correction system 3 controller 10 robot 11 welding gun (robot gun)
11bc First mounting portion 11bd Second mounting portion 11d Electrode tip (electrode)
20 Robot control device 30 Image processing device 50, 50A Imaging device 51 Camera 52, 52A Attachment

Claims (22)

A correction system for correcting teaching data of a robot,
a camera mounted on the first mounting portion operable in a first direction of the opposing first mounting portion and the second mounting portion of the robot gun of the robot;
a fixture that attaches the camera to the first mounting portion such that the direction of the optical axis of the camera is offset from the first mounting portion;
a control device;
The control device is
When the robot gun is positioned at the teaching position for pressing the first mounting section against the predetermined hitting position of the workpiece between the first mounting section and the second mounting section in accordance with the teaching data, the predetermined causing the camera to image the dot mark attached to the dot position;
using the image captured by the camera to detect the position of the dot mark;
detecting a corresponding position that is a position of the robot gun for pressing the first mounting part against the hitting mark;
A correction system that corrects the teaching data based on the difference between the corresponding position and the teaching position. The control device is
when the robot gun is positioned at the teaching position, operating the first mounting section in the first direction toward the workpiece according to the teaching data;
2. The correction system according to claim 1, wherein said camera in a state of being close to said work is caused to image said dot mark. An electrode for welding can be attached to and detached from the first attachment portion and the second attachment portion,
3. The correction system of claim 1 or 2, wherein the fixture is attached to the first mount instead of the electrode. An electrode for welding can be attached to and detached from the first attachment portion and the second attachment portion,
3. The correction system of claim 1 or 2, wherein the fixture is configured to be attachable to the first mounting part with the electrode attached to the first mounting part. The length by which the mounting fixture and the camera attached to the first mounting portion protrude from the first mounting portion in the first direction is determined by 5 . The correction according to any one of claims 1 to 5, wherein the fixture offsets the direction of the optical axis of the camera so that the direction of the optical axis of the camera intersects the first direction. system. The correction system according to any one of claims 1 to 5, wherein the fixture offsets the direction of the optical axis of the camera such that the direction of the optical axis of the camera is parallel to the first direction. the teaching position includes a three-dimensional position and orientation of the robot gun at the teaching position;
the corresponding position includes a three-dimensional position and orientation of the robot gun at the corresponding position;
The control device corrects the teaching data based on a difference between the three-dimensional position and orientation of the robot gun at the corresponding position and the three-dimensional position and orientation of the robot gun at the teaching position. 8. A compensation system according to any one of clause 7. The correction according to any one of claims 1 to 8, wherein the control device moves the robot gun so as to press the second mounting section against the workpiece at the teaching position before imaging with the camera. system. 10. The correction system according to any one of claims 1 to 9, wherein the dot mark is a marking that includes a center display portion indicating a center and an orientation display portion indicating an orientation in rotation about the center. a correction system according to any one of claims 1 to 10;
and the robot;
The robot system, wherein the controller controls an operation of the robot. A correction method for correcting teaching data of a robot,
The robot gun of the robot is moved to a teaching position for pressing the first mounting section against a predetermined hitting position of the workpiece between the opposing first mounting section and the second mounting section of the robot gun according to the teaching data. and
When the robot gun is positioned at the teaching position, causing a camera attached to the first mounting portion to image a dot mark attached to the predetermined dot position;
detecting the position of the dot mark using the image captured by the camera;
detecting a corresponding position, which is a position of the robot gun for pressing the first mounting part against the hitting mark;
correcting the teaching data based on the difference between the corresponding position and the teaching position;
wherein the camera is mounted on the first mounting part such that the direction of the optical axis of the camera is offset from the first mounting part operable in a first direction. further comprising, when the robot gun is positioned at the teaching position, operating the first mounting section in the first direction toward the workpiece according to the teaching data;
13. The correction method according to claim 12, wherein the image of the dot mark is captured by the camera while the camera is close to the workpiece. An electrode for welding can be attached to and detached from the first attachment portion and the second attachment portion,
The correction method according to claim 12 or 13, wherein the camera is attached to the first attachment section instead of the electrode. An electrode for welding can be attached to and detached from the first attachment portion and the second attachment portion,
14. The correction method according to claim 12 or 13, wherein the camera is configured to be attachable to the first mounting part with the electrodes attached to the first mounting part. The length by which the camera attached to the first mounting portion protrudes in the first direction from the first mounting portion is such that the electrode attached to the first mounting portion protrudes from the first mounting portion to the first mounting portion. 16. The correction method according to claim 14 or 15, wherein the length is equal to or less than the length projecting in the direction. The correction method according to any one of claims 12 to 16, wherein the direction of the optical axis of the camera is offset such that the direction of the optical axis of the camera is a direction that intersects the first direction. The correction method according to any one of claims 12 to 16, wherein the direction of the optical axis of the camera is offset such that the direction of the optical axis of the camera is parallel to the first direction. correcting the teaching data based on a difference between the three-dimensional position and orientation of the robot gun at the corresponding position and the three-dimensional position and orientation of the robot gun at the teaching position;
the teaching position includes a three-dimensional position and orientation of the robot gun at the teaching position;
The correction method according to any one of claims 12 to 18, wherein the corresponding position includes a three-dimensional position and orientation of the robot gun at the corresponding position. The correction method according to any one of claims 12 to 19, further comprising moving the robot gun so as to press the second mounting section against the workpiece at the teaching position before imaging with the camera. . The correction method according to any one of claims 12 to 20, wherein the dot mark is a marking including a center display portion indicating a center and a direction display portion indicating a direction in rotation around the center. A control device for executing the correction method according to any one of claims 12 to 21.

Images