WO2021070922A1 - Correction system, correction method, robot system, and control device - Google Patents

Abstract

This correction system (2) is provided with: a camera (51) which is mounted on a first mounting unit (11bc) that is operable in a first direction of a robot gun (11) of a robot (10); a fitting tool (52) by which the camera is fit to the first mounting unit so that an optical axis direction of the camera is to be offset from the first mounting unit; and a control device (3), wherein, when the robot gun is positioned at a teaching position for pushing the first mounting position to a prescribed hitting position of a workpiece according to teaching data, the control device causes the camera to capture an image of a hitting mark at the prescribed hitting position, detects the position of the hitting mark by using the captured image, detects a corresponding position of the robot gun for pushing the first mounting unit to the hitting mark, and corrects the teaching data on the basis of the difference between the corresponding position and the teaching position.

Description

Correction system, correction method, robot system and control device Cross-reference to related applications

This application claims the priority of Japanese Patent Application No. 2019-186010 filed with the Japan Patent Office on October 9, 2019, and is a part of this application by referring to the whole. To quote.

This disclosure relates to a correction system, a correction method, a robot system and a control device.

Conventionally, a technique for automatically correcting the teaching data of a robot is known. For example, Patent Document 1 discloses a teaching position correction system for a welding robot. The teaching position correction system comprises an imaging device attached to or interchanged with one of the two opposed electrodes of the welding gun. The optical axis of the image pickup apparatus is coaxial with the axis of one of the electrodes. In the teaching position correction system, the imaging device welds based on the position information of the welding point of the work in the image captured by the imaging device, the distance from the imaging device to the welding point, and the clearance between the work and the other electrode. Correct the teaching position of the welding gun so that the points can be imaged.

Japanese Unexamined Patent Publication No. 2008-132525

In the system of Patent Document 1, the imaging device is attached to or replaced with one electrode of the welding gun. The length of the image pickup device is generally larger than the length of the electrodes. For example, if the electrodes of the welding gun are operated so as to close the gap between the electrodes according to the teaching data, the imaging device may be crushed. 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 becomes large, the accuracy of the welding point position information obtained by processing the image of the welding point becomes low, and the correction accuracy of the teaching position may become low.

Therefore, an object of the present disclosure is to provide a correction system, a correction method, a robot system, and a control device that improve the correction accuracy of the teaching data.

In order to achieve the above object, the correction system according to one aspect of the present disclosure is a correction system that corrects the teaching data of the robot, and is a correction system of the first mounting portion and the second mounting portion of the robot gun of the robot facing each other. A camera attached to the first mounting portion that can operate in the first direction, and a mounting that attaches the camera to the first mounting portion so that the direction of the optical axis of the camera is offset from the first mounting portion. The control device includes a tool and a control device, and the control device is a teaching for pressing the first mounting portion to a predetermined hitting point position of a work between the first mounting portion and the second mounting portion according to the teaching data. When the robot gun is positioned at the position, the camera is made to image the dot mark attached to the predetermined dot position, and the position of the dot mark is detected by using the image captured by the camera. The corresponding position, which is the position of the robot gun for pressing the first mounting portion against the hitting point mark, is detected, and the teaching data is corrected based on the difference between the corresponding position and the teaching position.

The robot system according to one aspect of the present disclosure includes a correction system according to one aspect of the present disclosure and the robot, and the control device controls the operation of the robot.

The correction method according to one aspect of the present disclosure is a correction method for correcting the teaching data of the robot, in which the work between the first mounting portion and the second mounting portion of the robot gun of the robot facing each other according to the teaching data. Moving the robot gun to a teaching position for pressing the first mounting portion to a predetermined hitting point position, and when the robot gun is located at the teaching position, to a camera mounted on the first mounting portion. To image the dot mark attached to the predetermined dot position, detect the position of the dot mark using the image captured by the camera, and attach the first mounting portion to the dot mark. The camera includes the detection of a corresponding position, which is the position of the robot gun for pressing, and the correction of the teaching data based on the difference between the corresponding position and the teaching position. The shaft is attached to the first mounting portion so as to be offset from the first mounting portion that can operate in the first direction.

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

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

FIG. 1 is a schematic view showing an example of a robot system according to an embodiment. FIG. 2 is a side view showing an example of the configuration of the welding gun according to the embodiment. FIG. 3 is a side view showing an example of a configuration in which an imaging device is mounted instead of an electrode tip in the welding gun of FIG. FIG. 4 is a block diagram showing an example of the hardware configuration of the robot system according to the embodiment. FIG. 5 is a block diagram showing an example of the functional configuration of the robot system according to the embodiment. FIG. 6 is a diagram showing an example of marking of a dot mark according to an embodiment. FIG. 7 is a side view showing an example of a state at the time of imaging of the dot mark by the camera in the correction mode. FIG. 8 is a diagram showing an example of an image captured by the camera in the state of FIG. 7. FIG. 9 is a flowchart showing an example of the operation of the robot system according to the embodiment in the correction mode. FIG. 10 is a side view showing an example of the configuration of the image pickup device for the welding gun according to the modified example.

First, an example of the embodiment of the present disclosure will be described. The correction system according to one aspect of the present disclosure is a correction system that corrects the teaching data of the robot, and can operate in the first direction of the facing first mounting portion and the second mounting portion of the robot gun of the robot. The camera is attached to the first mounting portion, the mounting tool for mounting the camera to the first mounting portion so that the direction of the optical axis of the camera is offset from the first mounting portion, and a control device. In the control device, the robot gun is positioned at a teaching position for pressing the first mounting portion to a predetermined hitting point position of the work between the first mounting portion and the second mounting portion according to the teaching data. At that time, the camera is made to image the dot mark attached to the predetermined dot position, the position of the dot mark is detected by using the image captured by the camera, and the first mounting portion is attached to the dot mark. The corresponding position, which is the position of the robot gun for pressing the camera, 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 can be suppressed in the first direction. As a result, when imaging with the camera, for example, even if the first mounting portion is operated in the first direction according to the teaching data, the camera is brought close to the dot mark without being crushed between the first mounting portion and the work. be able to. Therefore, the camera can take an image of the hitting point mark in a state where the first mounting portion is operated toward the hitting point position, and can take an image showing the relative position of the hitting point mark with high accuracy and high image quality. Therefore, it is possible to improve the detection accuracy of the corresponding position and the correction accuracy of the teaching data.

In the correction system according to one aspect of the present disclosure, when the robot gun is located at the teaching position, the control device operates the first mounting portion in the first direction toward the work according to the teaching data. , 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 in which the relative position of the dot mark is represented by the camera with high accuracy and high image quality, and it is possible to improve the accuracy of correction of teaching data.

In the correction system according to one aspect of the present disclosure, electrodes for welding can be attached to and detached from the first mounting portion and the second mounting portion, and the mounting tool is the first mounting instead of the electrodes. It may be attached to the part.

According to the above aspect, since the camera is attached to the first mounting portion instead of the electrodes, the camera can image the portion of the work in which the electrodes come into contact. Such a camera can capture an image showing the relative position of the dot mark corresponding to the portion where the electrodes are in contact with high accuracy and high image quality.

In the correction system according to one aspect of the present disclosure, electrodes for welding can be attached to and detached from the first mounting portion and the second mounting portion, and in the mounting tool, the electrodes are attached to the first mounting portion. It may be configured so that it can be attached to the first attachment portion in the attached state.

According to the above configuration, for example, the camera can capture an image in a state where the first mounting portion is moved in the first direction and the electrodes are in contact with the work. Since such an image shows the actual hitting point position of the electrode and the hitting point mark together, it enables highly accurate and simple detection of the relative position between the actual hitting point position and the hitting point mark.

In the correction system according to one aspect of the present disclosure, the length of the attachment attached to the first mounting portion and the camera protruding from the first mounting portion in the first direction is determined by the first mounting portion. The attached electrode may have a length or less that protrudes from the first mounting portion in the first direction.

According to the above aspect, when the first mounting portion is operated in the first direction according to the teaching data, the camera and the fixture approach the work to the same extent as the electrodes or less, but the camera and the fixture are pressed against the work and damaged. Is suppressed.

In the correction system according to one aspect of the present disclosure, 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 kept small. Therefore, it is possible to save space for mounting the camera on the first mounting portion.

In the correction system according to one aspect of the present disclosure, the fixture may offset the direction of the optical axis of the camera so 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 captured by the camera is suppressed. Therefore, it is possible to simplify the image processing for detecting the dot mark.

In the correction system according to one aspect of the present disclosure, the teaching position includes the three-dimensional position and orientation of the robot gun at the teaching position, and the corresponding position is the three-dimensional position of the robot gun at the corresponding position. And the posture, the control device corrects the teaching data based on the difference between the three-dimensional position and posture of the robot gun at the corresponding position and the three-dimensional position and posture 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 one aspect of the present disclosure, the control device may move the robot gun at the teaching position so as to press the second mounting portion against the work 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, the process of detecting 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 one aspect of the present disclosure, the dot mark may be a marking including a center display unit indicating the center and a directional display unit indicating the direction in rotation around the center.

According to the above aspect, it is possible to detect the three-dimensional position and posture of the robot gun as the corresponding position of the robot gun with respect to the hitting point mark. The correction of the teaching data using such a corresponding position enables highly accurate correction.

The robot system according to one aspect of the present disclosure includes a correction system according to one aspect of the present disclosure and the robot, and the control device 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 disclosure can be obtained.

The correction method according to one aspect of the present disclosure is a correction method for correcting the teaching data of the robot, in which the work between the first mounting portion and the second mounting portion of the robot gun of the robot facing each other according to the teaching data. Moving the robot gun to a teaching position for pressing the first mounting portion to a predetermined hitting point position, and when the robot gun is located at the teaching position, to a camera mounted on the first mounting portion. To image the dot mark attached to the predetermined dot position, detect the position of the dot mark using the image captured by the camera, and attach the first mounting portion to the dot mark. The camera includes the detection of a corresponding position, which is the position of the robot gun for pressing, and the correction of the teaching data based on the difference between the corresponding position and the teaching position. The shaft is attached to the first mounting portion so as to be offset from the first mounting portion that can operate in the first direction. According to the above aspect, the same effect as that of the correction system according to one aspect of the present disclosure can be obtained.

The correction method according to one aspect of the present disclosure further includes operating the first mounting portion in the first direction toward the work according to the teaching data when the robot gun is located at the teaching position. The image of the dot mark by the camera may be performed in a state where the camera is close to the work.

In the correction method according to one aspect of the present disclosure, electrodes for welding can be attached to and detached from the first mounting portion and the second mounting portion, and the camera has the first mounting portion instead of the electrodes. It may be attached to.

In the correction method according to one aspect of the present disclosure, electrodes for welding can be attached to and detached from the first mounting portion and the second mounting portion, and in the camera, the electrodes are attached to the first mounting portion. It may be configured so that it can be attached to the first mounting portion in the state of being welded.

In the correction method according to one aspect of the present disclosure, the length of the camera mounted on the first mounting portion protruding from the first mounting portion in the first direction is the length of the camera mounted on the first mounting portion. The length of the electrode may be less than or equal to the length of protrusion from the first mounting portion in the first direction.

In the correction method according to one aspect of the present disclosure, the direction of the optical axis of the camera may be offset so that the direction of the optical axis of the camera intersects the first direction.

In the correction method according to one aspect of the present disclosure, the direction of the optical axis of the camera may be offset so 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 disclosure, the teaching data is obtained 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. Corrected, 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 one aspect of the present disclosure may further include moving the robot gun at the teaching position so as to press the second mounting portion against the work before imaging with the camera.

In the correction method according to one aspect of the present disclosure, the dot mark may be a marking including a center display unit indicating the center and a directional display unit indicating the direction in rotation around the center.

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

(Embodiment)
Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. It should be noted that all of the embodiments described below show comprehensive or specific examples. Further, among the components in the following embodiments, the components not described in the independent claims indicating the highest level concept are described as arbitrary components. Further, each figure in the attached drawings is a schematic view and is not necessarily exactly illustrated. Further, in each figure, substantially the same components are designated by the same reference numerals, and duplicate description may be omitted or simplified. Further, in the present specification and claims, the "device" may mean not only one device but also a system including a plurality of devices.

[Robot system configuration]
The configuration of the robot system 1 according to the embodiment will be described. FIG. 1 is a schematic view showing an example of the robot system 1 according to the 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 image pickup device 50. The robot control device 20, the image processing device 30, and the image pickup 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 make the robot 10 automatically operate according to the instructed operation procedure to execute a predetermined work. The robot system 1 can cause the robot 10 to manually operate according to the operation information input via the input device 40 to execute the work. The robot system 1 can execute a process of automatically correcting the teaching data with the data of the taught operation procedure. The robot system 1 operates by selecting one of an automatic operation mode in which the robot 10 is automatically operated, a manual operation mode in which the robot 10 is manually operated, and a correction mode in which the teaching data is automatically corrected. In the present embodiment, the work executed by the robot 10 is a welding work, for example, a spot welding work. The work executed by the robot 10 may be a welding work other than spot welding, or may be a work other than the welding work. Such work may include positioning a movable portion of the robot 10 with respect to an object, such as drilling, screwing, 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 welded portion of a welding object W, which is an example of a work, and a robot arm 12 that moves the end effector 11 to the welded portion. 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 a "welding gun 11". The object W to be welded is, for example, two stacked thin plate-like objects.

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

The robot arm 12 is fixedly arranged on an installation surface such as a floor surface, but may be arranged and movable on a transport vehicle or the like. The robot arm 12 includes joints JT1 to JT6 that sequentially connect links 12a to 12f, links 12a to 12f, which are sequentially arranged from the base to the tip, and arm drive devices M1 to rotationally drive each of the joints JT1 to JT6. It is equipped with M6. The operations of the arm drive devices M1 to M6 are controlled by the robot control device 20. Each of the arm drive devices M1 to M6 uses electric power as a power source and has a servomotor as an electric motor for driving the electric power, but the arm drive devices M1 to M6 are not limited thereto. The number of joints of the robot arm 12 is not limited to 6, but may be 7 or more, or 1 or more and 5 or less.

The joint JT1 rotatably connects the installation surface of the robot arm 12 and the base end portion of the link 12a around an axis in the vertical direction perpendicular to the installation surface. The joint JT2 rotatably connects the tip end of the link 12a and the base end of the link 12b around a horizontal axis parallel to the installation surface. The joint JT3 rotatably connects the tip end of the link 12b and the base end of the link 12c around an axis in the horizontal direction. The joint JT4 rotatably connects the tip end of the link 12c and the base end of the link 12d around the longitudinal axis of the link 12c. The joint JT5 rotatably connects the tip end of the link 12d and the base end of the link 12e about an axis in a direction orthogonal to the longitudinal direction of the link 12d. The joint JT6 connects the tip end of the link 12e and the base end of the link 12f in a twistable and rotatable manner with respect to the link 12e. The tip of the link 12f constitutes a mechanical interface and is connected to the welding gun 11.

FIG. 2 is a side view showing an example of the configuration of the welding gun 11 according to the embodiment. FIG. 3 is a side view showing an example of a configuration in which the imaging device 50 is mounted in place of the electrode tip 11d in the welding gun 11 of 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 main body portion 11b, and a moving device 11c. The mounting portion 11a is configured to be connected to the mechanical interface of the link 12f and supports the main body portion 11b. The main body portion 11b is composed of a U-shaped member and is connected to the mounting portion 11a. In the present embodiment, the main body portion 11b is made of the same material as the mounting portion 11a and is integrated with the mounting portion 11a. The main body portion 11b is connected to the mounting 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 so as to face each other in the direction D1, and the first mounting portion 11bc can move in the direction D1 approaching the second mounting portion 11bd and in the direction D2 away from the second mounting portion 11bd. The directions D1 and D2 are opposite to each other. Direction D1 is an example of the first direction.

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

The mobile drive mechanism 11 bc transmits the driving force of the mobile drive device 11ca to the first mounting portion 11 bc, and moves the first mounted portion 11 bc in the directions D1 and D2. The mobile drive mechanism 11 bc converts the rotational drive force of the mobile drive device 11ca into a linear drive force and transmits it to the first mounting portion 11 bc. The moving drive mechanism 11cc has, for example, a ball screw structure, and the nut is rotationally driven by the moving drive device 11ca to rotate the rod-shaped screw connected to the first mounting portion 11bc in the axial directions D1 and D2. Move to. The mobile drive 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 mobile drive device 11ca and the mobile drive mechanism 11 bc may be configured to move the first mounting portion 11 bc in the directions D1 and D2.

The second mounting portion 11bd is configured so that the electrode tip 11d, which is an example of an electrode for welding, can be attached and detached. For example, the electrode tip 11d may be configured to be attached by being inserted into a hole included in the second mounting portion 11bd. In the present embodiment, the shape of the electrode tip 11d is a cylindrical shape having a hemispherical tip, but the shape is not limited to this. The welding gun 11 includes a contact sensor 11e that detects contact between the electrode tip 11d mounted on the second mounting portion 11bd and the welding object W. The contact sensor 11e transmits a detection signal indicating contact between the electrode tip 11d and the welding object W to the robot control device 20. The configuration of the contact sensor 11e is not particularly limited as long as the contact can be detected, but in the present embodiment, a weak current is applied to the conductive electrode tip 11d of the second mounting portion 11bd to be a conductive welding target. The configuration is such that a signal representing a change in current at the time of contact with the object W is transmitted as a detection signal.

The first mounting portion 11bc is configured so that the electrode tip 11d can be attached and detached. Further, the first mounting portion 11bc is configured so that the imaging device 50 can be attached and detached instead of the electrode chip 11d. The electrode tip 11d and the image pickup apparatus 50 can be exchanged with each other and attached to the first mounting portion 11bc. For example, the electrode tip 11d and the image pickup apparatus 50 may be configured to be attached by being inserted into a hole included in the first mounting portion 11bc.

The image pickup device 50 has a camera 51 and a fixture 52. The camera 51 is a small camera that captures a digital image. An example of the camera 51 is an image sensor such as a CMOS (Complementary Metal-Oxide Semiconductor) image sensor and a CCD (Charge Coupled Device) image sensor. The camera 51 is controlled in operation by the robot control device 20, and transmits a signal of the captured image to the robot control device 20 and / or the image processing device 30. In the present embodiment, the camera 51 is a monocular camera, but is not limited thereto. For example, the camera 51 detects the position of a subject such as 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 cutting method. It may have a configuration for capturing an image of.

The attachment 52 attaches the camera 51 to the first attachment portion 11bc. The attachment 52 holds the camera 51 and is configured to be detachably attached to the first attachment portion 11bc. When the mounting tool 52 is mounted on the first mounting portion 11bc, the camera 51 is mounted on 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. In the present embodiment, the fixture 52 specifically offsets the direction of the optical axis 51a 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 by offsetting the optical axis 51a from the operation 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 diagonally. In the present embodiment, the axis 11da of the electrode chip 11d mounted on the first mounting portion 11bc and the optical axis 51a of the camera 51 mounted on the first mounting portion 11bc via the mounting tool 52 intersect. However, they may have a twisting relationship without intersecting. The axis 11da of the electrode tip 11d mounted on the first mounting portion 11bc is coaxial with the axis of the electrode tip 11d mounted on the second mounting 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 accommodating portion 52b accommodates and holds the camera 51 and its harness and the like, and exposes the lens of the camera 51 at the end portion connected to the connecting portion 52a. The axis of the connecting portion 52a connected to the first mounting portion 11bc is coaxial with, but is not limited to, the axis center 11da of the electrode tip 11d mounted on the first mounting portion 11bc. The axis of the accommodating portion 52b is coaxial with the optical axis 51a of the camera 51, but is not limited thereto. The accommodating portion 52b mounted on the first mounting portion 11bc extends from the connecting portion 52a in the direction D2 along a direction diagonally intersecting the direction of the axis of the connecting 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, and to suppress the amount of protrusion from the connecting portion 52a in the direction D1 to a low level or to prevent the housing portion 52b from protruding from the connecting portion 52a. Can be done.

Such a mounting tool 52 can suppress the length protruding from the first mounting portion 11bc in the direction D1 to a small size when mounted on the first mounting portion 11bc. In the present embodiment, the length of the fixture 52 and the camera 51 protruding from the first mounting portion 11bc in the direction D1 in the state of being mounted on the first mounting portion 11bc is such that the electrode tip 11d protrudes from the first mounting portion 11bc. It is less than or equal to the length protruding in the direction D1. As a result, the fixture 52 and the camera 51 mounted on the first mounting portion 11bc have the first mounting portion 11bc and the second mounting portion even when the first mounting portion 11bc is moved in the direction D1 due to the welding operation. It is suppressed from being strongly pressed against the welding object W between the 11b and the welding object W and being damaged.

As shown in FIG. 1, the input device 40 receives input of commands, information, data, etc. by the user of the robot system 1 and outputs the commands, information, data, etc. to the robot control device 20. The input device 40 is connected to the robot control device 20 via wired communication or wireless communication. The format of wired communication and wireless communication may be any format. For example, the input device 40 receives an input of a command for executing any 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 control device 20 controls the entire robot system 1. For example, the robot control device 20 may include a computer device.

The image processing device 30 generates image data from the signal of the image received from the camera 51, and performs image processing on the image data. For example, the image processing device 30 may include a computer device. The image processing device 30 detects the three-dimensional position and orientation of the subject projected on the image data by performing image processing. In the present specification and the scope of the claim, the "three-dimensional position" may be a three-dimensional position in the three-dimensional space, and the "posture" may be the three-dimensional posture in the three-dimensional space. It may be a two-dimensional posture in a two-dimensional plane such as a plane of an image or a plane along a plane intersecting the plane. For example, the camera 51 takes an image of a dot mark attached to a predetermined dot position on the surface of the welding object W, and the image processing device 30 detects the three-dimensional position and orientation of the dot mark projected on the image data. The predetermined striking point position is a position to be welded when the robot 10 performs a welding operation according to the teaching data in the automatic operation mode, and is a position to be pressed against the electrode tip 11d of the welding gun 11. Examples of dot marks are spot weld marks made on the surface of the object W to be welded, markings including figures and the like. When the dot mark has no 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 the welding work by automatic operation according to the teaching data, the actual hitting point position where the robot 10 actually performs welding and the robot 10 should originally perform welding. The teaching data is corrected so as to reduce the difference that occurs with the predetermined spot position. A dot mark is attached to such a predetermined dot position, and the dot mark may be attached to the surface of the welding object W by marking the position positioned by calculation or the like, and the instructor manually operates the spot mark. By actually causing the robot 10 to perform welding work, welding marks may be formed on the surface of the object to be welded W.

[Hardware configuration of robot system]
The 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, and an input / output I / F ( Interface) 205 to 207, arm drive circuit 208, and gun drive circuit 209 are included as components. Each of the above components is connected via bus, wired or wireless communication. Not all of the above components are essential.

For example, the CPU 201 is a processor and controls the entire operation of the robot control device 20. The ROM 202 is composed of a non-volatile semiconductor memory or the like, and stores a program, data, or the like for causing the CPU 201 to control the operation. The RAM 203 is composed of a volatile semiconductor memory or the like, and temporarily stores a program executed by the CPU 201 and data in the middle of processing or processed. The memory 204 is composed of a semiconductor memory such as a volatile memory and a non-volatile memory, and a storage device such as a hard disk (HDD: Hard Disc Drive) and an SSD (Solid State Drive), and stores various information. The memory 204 may be a device external to the robot control device 20.

For example, the program for operating the CPU 201 is stored in the ROM 202 or the memory 204 in advance. The CPU 201 reads a program from the ROM 202 or the memory 204 into the RAM 203 and develops the program. The CPU 201 executes each coded instruction in the program expanded in the RAM 203.

Each function of the robot control device 20 may be realized by a computer system including a CPU 201, a ROM 202, a RAM 203, or the like, or may be realized by a dedicated hardware circuit such as an electronic circuit or an integrated circuit, and the computer system and hardware may be realized. 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, etc. to the input device 40. The first input / output I / F 205 may include a circuit for converting a signal or the like. The second input / output I / F 206 is connected to the image processing device 30 and inputs / outputs information, data, commands, and the like to the image processing device 30. The second input / output I / F 206 may include a circuit for converting a signal or the like. The third input / output I / F 207 is connected to the camera 51 and inputs / outputs information, data, commands, etc. to the camera 51. The third input / output I / F 207 may include a circuit or the like for driving the camera 51.

The arm drive circuit 208 supplies electric power to the servomotors of the arm drive devices M1 to M6 of the robot 10 and controls the drive of the servomotors in accordance with the command of the CPU 201. The gun drive circuit 209 supplies electric power to the servomotor of the mobile drive device 11ca of the welding gun 11 to control the drive of the servomotor in accordance with the command of the CPU 201.

The image processing device 30 includes a CPU 301, a ROM 302, a RAM 303, a memory 304, and input / output I / F 305 to 306 as components. Each of the above components is connected via bus, wired or wireless communication. Not all of the above components are essential. The 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 the robot control device 20. The second input / output I / F 306 is connected to the camera 51 and inputs / outputs information, data, commands, etc. to the camera 51. For example, the second input / output I / F 306 receives the signal of the image captured by the camera 51. The input / output I / F 305 to 306 may include a circuit for converting a signal or the like.

The robot control device 20 and the image processing device 30 as described above include, for example, a microcontroller, an MPU (Micro Processing Unit), an LSI (Large Scale Integration), a system LSI, a PLC (Programmable Logic Controller), and logic. It may be composed of a circuit or the like. The plurality of functions of the robot control device 20 may be realized by being individually integrated into one chip, or may be realized by being integrated into one chip so as to include a part 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 connection and / or setting of circuit cells inside the LSI, or multiple functions for a specific application. An ASIC (Application Specific Integrated Circuit) or the like in which the above circuits are integrated may be used.

[Functional configuration of robot system]
The 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 image pickup 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, and a correction unit 20f. A storage unit of 20 g is included as a functional component. The motion control unit 20e includes an arm control unit 20ea and a gun control unit 20eb. Not all of the above functional components are required. The functions of the functional components other than the storage unit 20g are realized by the CPU 201 and the like, and the functions of the storage unit 20g are realized by the memory 204, the ROM 202 and / or the RAM 203.

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

In the present embodiment, the teaching method of the robot 10 is teaching by programming, and the teaching data 20ga is offline teaching data. The teaching method of the robot 10 may be, for example, direct teaching by the instructor moving the robot 10 in direct contact, teaching by remote control using a teaching pendant, teaching by a master / slave, or the like. In the welding work of the robot 10 according to the offline teaching data, the actually welded position may not match the position to be originally welded due to factors such as individual differences in the operation of the robot 10. In the welding work of the robot 10 according to the teaching data taught by the instructor, the actually welded position may not match the position to be originally welded due to factors such as a difference in the skill level of the instructor. Therefore, it is necessary to correct the teaching data of 20 ga.

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 position etc. For example, the welding position is the position of the hitting point where the electrode tip 11d is pressed onto the object to be welded. The gun teaching position may include the three-dimensional position and orientation of the welding gun 11. The electrode teaching position is a position relative to the welding gun 11 of the first mounting portion 11bc, 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 a force applied by the welding gun 11 to the welding object at each gun teaching position, or may include a force applied by the first mounting portion 11bc to the welding object via the electrode tip 11d.

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

Further, the storage unit 20g stores information on the welding gun 11, the electrode tip 11d, the object to be welded, and the imaging device 50. The information of the welding gun 11 includes the distance between the first mounting portion 11bc and the second mounting portion 11bd retracted to the end portion 11ba of the welding gun 11, 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 mounted on the first mounting portion 11bc and the second mounting portion 11bd. Information on the object to be welded includes dimensions such as the type, material and thickness of the object to be welded. The information of the image pickup apparatus 50 includes the information of the camera 51 and the fixture 52. The information of the camera 51 includes the camera parameters of the camera 51, and the camera parameters include internal parameters related to the camera 51 itself and external parameters related to 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 accommodating portion 52b, such as the angle and separation distance between the axial center of the connecting portion 52a and the axial center of the accommodating portion 52b. The above information may be stored in the storage unit 20g by input via the input device 40, respectively.

The image pickup control unit 20a controls the image pickup operation of the camera 51. For example, the image pickup control unit 20a operates in the correction mode, and a welding object having a spot mark at the spot position is designated on the camera 51 of the image pickup device 50 mounted on the first mounting portion 11bc of the welding gun 11. The image is taken at the timing. In the present embodiment, in the correction mode, the robot 10 performs the same operation as the welding operation according to the teaching data 20ga. The object to be welded is located 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 to the predetermined spot position of the object to be welded according to the teaching data 20ga, the imaging control unit 20a has the spot mark attached to the predetermined spot position. Is imaged by the camera 51. Specifically, when the welding gun 11 is located 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 target according to the teaching data 20ga, and the timing when the welding gun 11 approaches the welding target. In, the image pickup control unit 20a causes the camera 51 to image the dot mark. The timing may be the timing when the camera 51 is closest to the welding target, and the first mounting portion 11bc is moving in the direction D1 toward the welding target or the first in the direction D2 away from the welding target. It may be a predetermined timing during the movement of the mounting portion 11bc. The image processing device 30 may include an image pickup control unit 20a.

The mode determination unit 20b determines the mode to be executed by the robot system 1 from the automatic operation mode, the manual operation mode, and the correction mode according to a command for designating the mode via the input device 40, and sets it as another functional component. Operate according to the determined mode.

The manual command generation unit 20c generates an operation command for causing the robot 10 to perform an operation corresponding to the operation information output from the input device 40 in the manual operation mode or when the instructor executes the instruction, and the operation control unit 20e Output to.

The automatic command generation unit 20d generates an operation command for automatically causing the robot 10 to perform a predetermined welding operation according to the teaching data 20ga in the automatic operation mode and the correction mode, and outputs the operation command to the operation control unit 20e. The automatic command generation unit 20d acquires welding work information via the input device 40, and reads and uses the teaching data 20ga corresponding to the welding work from the storage unit 20g. For example, in the automatic operation mode, the automatic command generation unit 20d generates an operation command for pressurizing the welding object by pressing the electrode tip 11d of the first mounting unit 11bc, but in the correction mode, the welding object is pressed. An operation command is generated in which the image pickup device 50 of the first mounting portion 11bc is brought into close contact with each other but not pressurized or not brought into contact with each other.

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 a force applied by the welding gun 11 to the welding object at each position and a force applied by the first mounting portion 11bc to the welding object via the electrode tip 11d.

The motion control unit 20e controls the motion of the robot 10 according to the motion command. The arm control unit 20ea of the operation control unit 20e generates a command for operating the servomotors of the arm drive devices M1 to M6 of the robot arm 12 so that the three-dimensional position and posture of the welding gun 11 obey the operation command. Then, the output is output to the arm drive devices M1 to M6. The arm control unit 20ea acquires the rotation amount and drive current of each of the servomotors of the arm drive devices M1 to M6 as feedback information and uses them to generate the above command. The gun control unit 20eb generates a command for operating the servomotor of the movement drive device 11ca of the welding gun 11 and outputs the command to the movement drive device 11ca so that the position of the first mounting unit 11bc follows the operation command. .. The gun control unit 20eb acquires the rotation amount and the drive current of the servomotor of the mobile drive device 11ca as feedback information and uses them for generating the above command.

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

Further, the correction unit 20f has a corresponding position of the welding gun 11 for actually executing welding at the center of the dot mark and a gun teaching position of the welding gun 11 set for executing welding at the center of the dot mark. The teaching data 20ga is corrected based on the difference from the above. The correction unit 20f may correct the gun teaching position so as to reduce the difference, or may correct the gun teaching position by replacing it with a corresponding position, for example.

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 components are required. The functions of the extraction unit 30a and the mark position detection unit 30b are realized by the CPU 301 and the like, and the functions of the storage unit 30c are realized by the memory 304, the ROM 302 and / or the RAM 303.

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

In the present 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 directionality which is the direction of the marking. FIG. 6 is a diagram showing an example of marking of a dot mark according to an embodiment. The marking M in FIG. 6 is 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. It is composed. The inner circumference Mc represents the center of the marking M and is an example of the center display unit. The equilateral triangle Mb and the point Md represent the direction of the marking M and are an example of the directional display unit.

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

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

In the correction mode, the extraction unit 30a detects a dot mark from the subject projected on the image data captured by the camera 51.

For example, when the spot welding mark is a spot welding mark, the extraction unit 30a executes binary conversion or the like on the image data to detect the edge. The extraction unit 30a compares the image data before conversion and the image data after conversion with the image data of spot welding marks, and executes shape pattern matching, color pattern matching, and / or texture pattern matching. , Detects the image of spot welding marks. The extraction unit 30a is based on information such as the angle between the axis of the connecting portion 52a of the attachment 52 and the axis of the accommodating portion 52b, and the axis 11da of the electrode tip 11d and the camera 51 in the first mounting portion 11bc. The distortion of the subject of the image data captured from an oblique direction may be corrected based on the detection result by detecting the angle with the optical axis 51a of the above. The extraction unit 30a may detect an image of a spot weld mark using the image data after distortion correction.

For example, when the dot mark is a marking, the extraction unit 30a executes a binary conversion or the like on the image data to detect an edge. The extraction unit 30a detects the marking image by comparing the converted image data with the marking image data and performing shape pattern matching. Alternatively, the extraction unit 30a detects the line segment and the arc by executing a 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 from the combinations of the detected figures, the combination forming the marking is a marking image. Detect as. The combination of figures includes the shape and arrangement of the figures. The extraction unit 30a detects a similar figure so as to consider the distortion of the subject of the image data captured from the oblique direction. For example, in the case of the marking M of FIG. 6, the extraction unit 30a includes the outermost circle or ellipse, the triangle inside the circle, the circle or ellipse inside the triangle, and the point inside one corner of the triangle. Detect combinations. The extraction unit 30a may correct the distortion of the subject 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 by using the image data captured by the camera 51 and the dot mark information 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 by taking the case of marking M as an example.

FIG. 7 is a side view showing an example of a state at the time of imaging the dot mark by the camera 51 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. 7. As shown in FIG. 8, the mark position detection unit 30b has the pixel coordinates of the pixel pMc at the center of the marking M, that is, the center of the inner circumference circle Mc, and the center of the circular point Md in the image Ia on which the marking M is copied. The pixel coordinates of the pixel pMd of the above are detected. The pixel coordinates are coordinates in the image coordinate system of the image Ia in units of pixels.

The position of the optical axis 51a of the camera 51 is the pixel pI at the center of the image Ia. The mark position detection unit 30b refers to the angle α of the line-of-sight LMc and the optical axis 51a from the camera 51 to the center of the inner peripheral circle Mc shown in FIG. 7 and the optical axis 51a based on the positional relationship between the pixel pMc and the pixel pI. Calculate the direction of the line of sight LMc. The intersection 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 hitting 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 unit 30b calculates the distance da between the tip of the first mounting unit 11bc and the surface of the welding object W at the time of imaging by the camera 51. Specifically, the mark position detection unit 30b acquires feedback information at the time of imaging of the camera 51 from the gun control unit 20eb of the robot control device 20, and detects the position of the first mounting unit 11bc based on the feedback information. The mark position detection unit 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 object W.

The mark position detection unit 30b has an inner circumference Mc based on the protrusion length of the fixture 52 from the first mounting portion 11bc in the direction D1, the direction and the 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 stored in advance in the storage unit 30c.

Further, 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 circumference circle Mc. The mark position detection unit 30b calculates the three-dimensional position of the center of the marking M and the posture of the marking M in the three-dimensional space based on the three-dimensional positions of the center of the inner circumference circle Mc and the center of the point Md. The posture of the marking M may be any posture, and may be, for example, an orientation in the horizontal direction of the center of the point Md with respect to the center of the marking M, and the three dimensions of the point Md with respect to the center of the marking M. It may be in the direction of the direction, or may be the amount of inclination and the 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 posture of the center of the marking M to the correction unit 20f of the robot control device 20.

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

[Operation of 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 flowchart showing an example of the operation of the robot system 1 according to the embodiment in the correction mode.

As shown in FIG. 9, first, in step S1, the electrode tip 11d of the first mounting portion 11bc of the welding gun 11 is replaced with the imaging device 50 by the user. That is, the attachment 52 of the image pickup apparatus 50 is attached to the first attachment portion 11bc. Next, in step S2, a command to execute the correction mode is input to the input device 40 by the user and accepted by the robot control device 20.

Next, in step S3, the robot control device 20 causes the robot 10 to automatically operate according to the teaching data 20ga of the storage unit 20g. Next, in step S4, the robot control device 20 moves the welding gun 11 to the robot 10 to the spot position where the welding gun 11 should be placed next among the plurality of spot 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 posture of the welding gun 11 with respect to the striking 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 striking point position. Further, the robot control device 20 moves the welding gun 11 in the direction D2 with respect to the welding object W, so that the electrode tip 11d of the second mounting portion 11bd is brought into contact with the welding object W. 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 moves the first mounting portion 11bc in the direction D1 to the moving device 11c, moves it in the direction D2 after making it closest to the welding object W, and separates it from the welding object W. Let me. At this time, the robot control device 20 does not press the image pickup device 50 against the welded object W to pressurize it as in the case of the automatic operation mode, but brings the image pickup device 50 into contact with the welded object W. Do not pressurize or contact.

Next, in step S7, the robot control device 20 takes the camera 51 at a predetermined timing in the process in which the first mounting portion 11bc approaches the welding target W or the process in which the first mounting portion 11bc leaves the welding target W. To image the surface of the object W to be welded. The robot control device 20 may or may not temporarily stop the first mounting portion 11bc at the time of imaging. The camera 51 transmits the signal of the captured image to the image processing device 30 in association with the information of the hitting point position and stores it as image data in the storage unit 30c, but it may be transmitted to the robot control device 20 and stored in the storage unit 20g. Good.

Next, in step S8, the robot control device 20 determines whether or not the welding operation to all the hitting point positions included in the teaching data 20ga is completed. The robot control device 20 proceeds to step S9 when it is completed (Yes in step S8), and proceeds to step S4 when it is not completed (Nо in step S8).

In step S9, the image processing device 30 detects the dot mark projected on 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 dot mark information detected in the image data. The image processing device 30 associates the information of each hitting point position with the three-dimensional position and posture of the hitting point mark at the hitting point position and transmits the information 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 executing welding at the center of the dot mark based on the three-dimensional position and posture of the dot mark for each dot position. To do. Next, in step S12, the robot control device 20 corresponds to the gun teaching position of the welding gun 11 set to execute welding at the hitting point position and the welding gun 11 at the hitting point position. The teaching data 20ga is corrected based on the difference from the position.

By the processing of steps S1 to S12, the robot system 1 can automatically image the dot marks corresponding to each dot position in order and correct the teaching data 20ga.

(Modification example)
In the robot system according to the modified example, the configuration of the image pickup device 50A that can be attached to and detached from the welding gun 11 is different from that of the embodiment. The fixture 52A of the image pickup apparatus 50A according to the modified example specifically offsets the direction of the optical axis 51a 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 11bc by offsetting the optical axis 51a from the operation path of the first mounting portion 11bc in the directions D1 and D2. Hereinafter, the present modification will be described with a focus on different points in the embodiment, and the same points as in the embodiment will be omitted as appropriate.

FIG. 10 is a side view showing an example of the configuration of the imaging device 50A of the welding gun 11 according to the modified example. The image pickup apparatus 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 accommodating portion 52Ab is parallel to the axis of the connecting portion 52Aa. Therefore, the optical axis 51a of the camera 51 mounted on the first mounting portion 11bc via the mounting tool 52A is parallel to the axis 11da of the electrode tip 11d mounted on the first mounting portion 11bc. Further, in this modification, the axis of the accommodating portion 52Ab is located away from the axis of the connecting portion 52Aa in a direction perpendicular to the axis of the connecting portion 52Aa. That is, the optical axis 51a and the axis 11da are separated from each other. The accommodating portion 52Ab extends from the connecting portion 52Aa in the direction D2. 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, and to suppress the amount of protrusion from the connecting portion 52Aa in the direction D1 to a low level, or to prevent the housing portion 52Ab from protruding from the connecting portion 52Aa. Can be done.

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

Further, in this modification, the axis of the accommodating portion 52Ab offset from the axis of the connection portion 52Aa is located away from the axis of the connection portion 52Aa, but the present invention is not limited to this, and the connection portion 52Aa It may be coaxial with the axis.

(Other embodiments)
Although the examples of the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments and modifications. That is, various modifications and improvements are possible within the scope of the present disclosure. For example, a form in which various modifications are applied to the embodiments and modifications, and a form constructed by combining components in different embodiments and modifications are also included in the scope of the present disclosure.

For example, in the embodiment and the modified example, in the correction mode, the robot control device 20 moves the welding gun 11 to the robot 10 according to the teaching data 20ga to each hitting point position, and further moves the first mounting portion 11bc to the welding object W. The camera is moved toward the camera to image the image on the 51, but the method is not limited to this. For example, the robot control device 20 causes the robot 10 to move the welding gun 11 to each hitting point position according to the teaching data 20ga, but the camera 51 may image the welding gun 11 without moving the first mounting portion 11bc. Good. Alternatively, the robot control device 20 moves the first mounting portion 11bc in the direction D1 toward the welding object W, but the position before the electrode tip 11d comes into contact with the welding object W, that is, the contact position. The first mounting portion 11bc may be stopped at a position closer to the direction D2 and then pulled back to the direction D2. In this case, the robot control device 20 may cause the camera 51 to take an image at the stop position, or may make the camera 51 take an image in the process of movement.

Further, 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 welding object before performing the imaging with the camera 51 in the correction mode. However, the present invention is not limited to this, and it is not necessary to make contact with the contact. In this case, the image processing device 30 may detect the distance between the camera 51 and the object to be welded by processing the image data captured by the camera 51.

Further, in the embodiment and the modified example, the attachments 52 and 52A of the image pickup apparatus 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. Not limited. For example, the attachments 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 attachments 52 and 52A may be configured so that the electrode tip 11d 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 attachments 52 and 52A may be configured to be attached to the first attachment portion 11bc together with the electrode tip 11d. For example, the attachments 52 and 52A may be attached to the first attachment portion 11bc laterally 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 the device is not limited to this, and may be included in one device. Further, the robot control device 20 and the image processing device 30 may both be composed of two or more devices.

Further, the technique of the present disclosure may be a correction method or a control device that executes the above correction method. For example, the correction method according to one aspect of the present disclosure is a correction method for correcting the teaching data of the robot, and is between the first mounting portion and the second mounting portion of the robot gun of the robot facing each other according to the teaching data. The robot gun is moved to a teaching position for pressing the first mounting portion to a predetermined hitting point position of the work, and when the robot gun is located at the teaching position, the robot gun is mounted on the first mounting portion. The camera is made to image the dot mark attached to the predetermined dot position, the position of the dot mark is detected by using the image captured by the camera, and the first attachment is made to the dot mark. The camera includes detecting a corresponding position, which is a position of the robot gun for pressing a unit, and correcting the teaching data based on a difference between the corresponding position and the teaching position. Is attached to the first mounting portion so that the direction of the optical axis of the above is offset from the first mounting portion that can operate in the first direction. Such a correction method may be realized by a circuit such as a CPU or an LSI, an IC card, a single module, or the like.

Further, the technique of the present disclosure may be a program that causes a computer to execute the correction method, or may be a non-temporary computer-readable recording medium in which the program is recorded. Needless to say, the above program can be distributed via a transmission medium such as the Internet.

In addition, the numbers such as the ordinal number and the quantity used above are all examples for concretely explaining the technology of the present disclosure, and the present disclosure is not limited to the illustrated numbers. Further, the connection relationship between the components is illustrated for the purpose of specifically explaining the technique of the present disclosure, and the connection relationship for realizing the function of the present disclosure is not limited thereto.

Further, the division of blocks in the functional block diagram is an example, and even if a plurality of blocks are realized as one block, one block is divided into a plurality of blocks, and / or some functions are transferred to another block. Good. In addition, a single piece of hardware or software may process the functions of a plurality of blocks having similar functions in parallel or in a time division manner.

1 Robot system 2 Correction system 3 Control device 10 Robot 11 Welding gun (robot gun)
11bc 1st mounting part 11bd 2nd mounting part 11d Electrode tip (electrode)
20 Robot control device 30 Image processing device 50, 50A Image pickup device 51 Camera 52, 52A Mounting tool

Claims (22)

1. It is a correction system that corrects the teaching data of the robot.
   A camera attached to the first mounting portion capable of operating in the first direction of the first mounting portion and the second mounting portion facing the robot gun of the robot, and a camera attached to the first mounting portion.
   A mounting tool for mounting the camera on the first mounting portion so that the direction of the optical axis of the camera is offset from the first mounting portion.
   Equipped with a control device
   The control device is
   When the robot gun is positioned at a teaching position for pressing the first mounting portion to a predetermined striking point position of the work between the first mounting portion and the second mounting portion according to the teaching data, the predetermined The camera is made to image the dot mark attached to the dot position.
   Using the image captured by the camera, the position of the dot mark is detected.
   The corresponding position, which is the position of the robot gun for pressing the first mounting portion against the hitting point mark, is detected.
   A correction system that corrects the teaching data based on the difference between the corresponding position and the teaching position.
2. The control device is
   When the robot gun is located at the teaching position, the first mounting portion is operated in the first direction toward the work according to the teaching data.
   The correction system according to claim 1, wherein the camera in a state of approaching the work captures the dot mark.
3. Electrodes for welding can be attached to and detached from the first mounting portion and the second mounting portion.
   The correction system according to claim 1 or 2, wherein the fitting is attached to the first mounting portion instead of the electrode.
4. Electrodes for welding can be attached to and detached from the first mounting portion and the second mounting portion.
   The correction system according to claim 1 or 2, wherein the attachment is configured so that the electrode can be attached to the first attachment while the electrode is attached to the first attachment.
5. The length of the attachment attached to the first mounting portion and the camera protruding from the first mounting portion in the first direction is such that the electrode attached to the first mounting portion is the first mounting portion. The correction system according to claim 3 or 4, wherein the length is less than or equal to the length protruding from the first direction.
6. 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.
7. 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 so that the direction of the optical axis of the camera is parallel to the first direction.
8. The teaching position includes the three-dimensional position and posture of the robot gun at the teaching position.
   The corresponding position includes the three-dimensional position and posture of the robot gun at the corresponding position.
   The control device corrects the teaching data based on the difference between the three-dimensional position and posture of the robot gun at the corresponding position and the three-dimensional position and posture of the robot gun at the teaching position. The correction system according to any one of 7.
9. The correction according to any one of claims 1 to 8, wherein the control device moves the robot gun at the teaching position so as to press the second mounting portion against the work 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 including a center display unit indicating the center and a directional display unit indicating the orientation in rotation around the center.
11. The amendment system according to any one of claims 1 to 10.
    Equipped with the robot
    The control device is a robot system that controls the operation of the robot.
12. It is a correction method that corrects the teaching data of the robot.
    According to the teaching data, the robot gun is moved to a teaching position for pressing the first mounting portion to a predetermined striking point position of the work between the first mounting portion and the second mounting portion of the robot gun of the robot. That and
    When the robot gun is located at the teaching position, the camera attached to the first mounting portion is made to image the dot mark attached to the predetermined dot position.
    Using the image captured by the camera, the position of the dot mark is detected, and
    Detecting the corresponding position, which is the position of the robot gun for pressing the first mounting portion against the hitting point mark, and
    Including correcting the teaching data based on the difference between the corresponding position and the teaching position.
    A correction method in which the camera is attached to the first mounting portion so that the direction of the optical axis of the camera is offset from the first mounting portion that can operate in the first direction.
13. Further including operating the first mounting portion in the first direction toward the work according to the teaching data when the robot gun is located at the teaching position.
    The correction method according to claim 12, wherein the camera captures the dot mark with the camera in close proximity to the work.
14. Electrodes for welding can be attached to and detached from the first mounting portion and the second mounting portion.
    The correction method according to claim 12 or 13, wherein the camera is attached to the first mounting portion instead of the electrodes.
15. Electrodes for welding can be attached to and detached from the first mounting portion and the second mounting portion.
    The correction method according to claim 12 or 13, wherein the camera is configured so that the electrode can be attached to the first mounting portion in a state where the electrode is attached to the first mounting portion.
16. The length of the camera attached to the first mounting portion protruding from the first mounting portion in the first direction is such that the electrode attached to the first mounting portion has the first mounting portion from the first mounting portion. The amendment method according to claim 14 or 15, wherein the length is equal to or less than the length protruding in the direction.
17. The correction method according to any one of claims 12 to 16, wherein the direction of the optical axis of the camera is offset so that the direction of the optical axis of the camera intersects the first direction.
18. The correction method according to any one of claims 12 to 16, wherein the direction of the optical axis of the camera is offset so that the direction of the optical axis of the camera is parallel to the first direction.
19. The teaching data is corrected based on the difference between the three-dimensional position and posture of the robot gun at the corresponding position and the three-dimensional position and posture of the robot gun at the teaching position.
    The teaching position includes the three-dimensional position and posture 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 a posture of the robot gun at the corresponding position.
20. 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 portion against the work at the teaching position before imaging with the camera. ..
21. The correction method according to any one of claims 12 to 20, wherein the dot mark is a marking including a center display unit indicating the center and a directional display unit indicating the orientation in rotation around the center.
22. A control device that executes the correction method according to any one of claims 12 to 21.

Images