Robotic system

Abstract

A robot system (1) comprises: a robot (2) which holds at least one of a first workpiece (10) and a second workpiece (20) arranged adjacent to each other; an illumination device (40) which irradiates slit-shaped light along a plane intersecting the boundary to the surfaces of the first workpiece (10) and the second workpiece (20) on both sides of a boundary (B) separating the first workpiece (10) and the second workpiece (20); a camera (50) which captures an image from a direction inclined relative to the plane, the image comprising a first line image (11) of light formed on the surface of the first workpiece (10) and a second line image (21) of light formed on the surface of the second workpiece (20); and a robot control device (30) which moves the robot (2) based on an offset amount and an offset direction of the second line image (21) relative to the first line image (11) in the image acquired by the camera (50) to correct a step between the surface of the first workpiece (10) and the surface of the second workpiece (20).

Description

Technical Field

[0001] The present disclosure relates to robotic systems. Background Art

[0002] The following method has been disclosed: in the corner joint welding of a pair of plate materials, a slit-shaped laser is irradiated from obliquely above the two plate materials at right angles to the welding line, and the optimal position of the welding gun is determined based on the projected line image, the intersection angle and the thickness of the two plate materials (for example, refer to Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 3-207577 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The method for determining the welding gun position of Patent Document 1 is a method for determining the optimal position of the welding gun, and therefore, if the position of the plate is misaligned, etc., accurate welding cannot be performed.

[0008] Therefore, it is desirable to appropriately correct the deviation of a pair of workpieces.

[0009] Solutions for solving problems

[0010] One aspect of the present disclosure provides a robot system, comprising: a robot that holds at least one of a first workpiece and a second workpiece that are arranged adjacent to each other; a lighting device that irradiates slit-shaped light onto the surfaces of the first workpiece and the second workpiece on both sides of a boundary between the first workpiece and the second workpiece along a plane intersecting the boundary; a camera that captures an image from a direction inclined relative to the plane, the image including a first line image of the light formed on the surface of the first workpiece and a second line image of the light formed on the surface of the second workpiece; and a robot control device that moves the robot based on an offset amount and an offset direction of the second line image relative to the first line image in the image acquired by the camera to correct the step between the surface of the first workpiece and the surface of the second workpiece. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 1 is an overall structural diagram of a robot system according to an embodiment of the present disclosure.

[0012] Figure 2 It is shown Figure 1 A diagram of the position of a first line image and a second line image in a robot system.

[0013] Figure 3 It is shown in Figure 1 A diagram showing a state in which the surface of the second base material is inclined relative to the surface of the first base material in the robot system.

[0014] Figure 4 It is shown Figure 3 A diagram showing the positions of the first line image and the second line image in the robot system in the state shown. DETAILED DESCRIPTION

[0015] Hereinafter, a robot system 1 according to an embodiment of the present disclosure will be described with reference to the drawings.

[0016] The robot system 1 of this embodiment is a system that aligns a flat first base material 10 and a flat second base material 20 so that the second base material (second workpiece) 20 is disposed at one edge of the first base material (first workpiece) 10 in a butted state and performs welding.

[0017] The robot system 1 includes a robot 2 that grips the second base material 20 , a robot control device 30 that controls the operation of the robot 2 , a lighting device 40 , and a camera 50 .

[0018] The first base material 10 is fixed to, for example, a workbench (not shown) in a state of being arranged substantially horizontally. The robot 2 arranges the held second base material 20 substantially horizontally near one edge of the first base material 10 .

[0019] The lighting device 40 is arranged above the first base material 10 and irradiates with a slit-shaped laser. The slit-shaped laser extends in a direction orthogonal to the boundary B between the first base material 10 and the second base material 20 when the second base material 20 is arranged adjacent to the first base material 10, and irradiates along a plane inclined at a predetermined angle relative to the surfaces of the first base material 10 and the second base material 20.

[0020] That is, the laser beam is irradiated onto the surfaces of the first base material 10 and the second base material 20 along a plane inclined at an angle less than 90° with respect to the surfaces of the first base material 10 and the second base material 20 .

[0021] Thus, a first line image 11 extending in a direction perpendicular to the boundary B is formed on the surface of the first base material 10 , and a second line image 21 extending in a direction perpendicular to the boundary B is formed on the surface of the second base material 20 .

[0022] The camera 50 is also disposed above the first base material 10. The camera 50 disposes the first line image 11 and the second line image 21 formed on both sides of the boundary B within the field angle and acquires a two-dimensional image including both the first line image 11 and the second line image 21.

[0023] The robot control device 30 processes the two-dimensional image acquired by the camera 50 and causes the robot 2 to perform a correction operation.

[0024] Specifically, the robot control device 30 measures the offset amount and offset direction between the first line image 11 and the second line image 21 in the two-dimensional image, and multiplies the measured offset amount by a predetermined constant to calculate the correction amount. Then, the robot control device 30 controls the robot 2 to move the second base material 20 to the side opposite to the measured offset direction by the calculated correction amount.

[0025] The offset direction between the first line image 11 and the second line image 21 in the two-dimensional image is measured by the offset direction in which the second line image 21 is offset relative to the first line image 11 in the two-dimensional image. Figure 2 This is an example of a two-dimensional image when the lighting device 40 is arranged at the position of the reference numeral 40. In this two-dimensional image, when the second line image 21 on the left is arranged on the upper side relative to the first line image 11 on the right, it can be seen that the second base material 20 is offset upward relative to the first base material 10. Conversely, in the two-dimensional image, when the second line image 21 on the left is arranged on the lower side relative to the first line image 11 on the right, it can be seen that the second base material 20 is offset downward relative to the first base material 10.

[0026] In addition, the offset between the first line image 11 and the second line image 21 in the two-dimensional image is measured by the number of pixels between the first line image 11 and the second line image 21 in the two-dimensional image. The conversion coefficient between the offset between the first line image 11 and the second line image 21 in the two-dimensional image measured by the number of pixels and the actual offset between the first matrix 10 and the second matrix 20 is roughly set in advance.

[0027] In the present embodiment, the constant multiplied by the number of pixels for calculating the correction amount is a number obtained by multiplying the conversion factor by a predetermined decimal.

[0028] Next, the operation of the robot system 1 according to the present embodiment configured as described above will be described.

[0029] According to the robot system 1 of this embodiment, as Figure 1 As shown, when the robot 2 arranges the second base material 20 at a position adjacent to one edge of the first base material 10 , the slit-shaped laser is irradiated by the lighting device 40 .

[0030] Thus, the laser light emitted from the lighting device 40 forms the first line image 11 and the second line image 21 extending in the direction orthogonal to the boundary B on the surfaces of the first base material 10 and the second base material 20 .

[0031] The laser is inclined at an angle less than 90° relative to the surfaces of the first matrix 10 and the second matrix 20. Therefore, when the first matrix 10 and the second matrix 20 are offset in the thickness direction, the first line image 11 and the second line image 21 are offset from each other in the direction along the boundary B and formed.

[0032] In this state, by operating the camera 50, the following Figure 2 The two-dimensional image shown is sent to the robot control device 30.

[0033] The two-dimensional image transmitted from the camera 50 is processed by the robot control device 30 .

[0034] Thus, the number of pixels between the first line image 11 and the second line image 21 in the two-dimensional image is measured. Next, the correction amount corresponding to the measured number of pixels is calculated by multiplying the measured number of pixels by a constant, which is a number obtained by multiplying the conversion coefficient between the positive decimal sum and the unit pixel and the actual offset amount in the first matrix 10 and the second matrix 20.

[0035] In addition, the offset direction of the second line image 21 in the two-dimensional image relative to the first line image 11 is detected as the offset direction of the second base material 20 relative to the first base material 10 in any upper and lower directions. The robot control device 30 determines the direction opposite to the detected offset direction of the first base material 10 and the second base material 20 as the correction direction.

[0036] Then, the robot control device 30 moves the robot 2 in the determined correction direction by the calculated correction amount.

[0037] At this time, even if the conversion coefficient multiplied by the number of pixels is inaccurate or there is an error in the movement amount of the robot 2 relative to the control command, by multiplying by a positive decimal, the calculated correction amount can be made smaller than the actual offset. Thus, the surface of the second base material 20 does not exceed the surface of the first base material 10, and the offset between the first base material 10 and the second base material 20 is corrected.

[0038] Furthermore, the robot control device 30 detects the offset between the first base material 10 and the second base material 20 after correction again, and compares it with a predetermined threshold value stored in advance.

[0039] As a result, when the detected offset between the corrected first matrix 10 and the second matrix 20 is greater than the threshold, the robot control device 30 moves the robot 2 again based on the detected offset and offset direction between the corrected first matrix 10 and the second matrix 20.

[0040] As a result, the amount of deviation between the first base material 10 and the second base material 20 is further reduced compared to after the previous calibration.

[0041] In this way, by repeating the correction action until the offset between the first line image 11 and the second line image 21 is less than the predetermined threshold value, the offset between the first matrix 10 and the second matrix 20 is gradually corrected. In addition, even if the correction action is repeated, the direction of correction is not reversed but is limited to the same direction, so that not only can the step between the first matrix 10 and the second matrix 20 be accurately corrected, but also the correction control method can be simplified.

[0042] As described above, according to the robot system 1 of the present embodiment, the relative positions of the first base material 10 and the second base material 20 can be corrected to an optimum state for butt welding, thereby enabling good welding to be performed.

[0043] Furthermore, in the present embodiment, the robot control device 30 calculates the correction amount of the robot 2 based on the offset between the first line image 11 and the second line image 21 in the two-dimensional image. Alternatively, the robot control device 30 may calculate the correction amount of the robot 2 based on the three-dimensional coordinate information in the actual space corresponding to the offset between the first line image 11 and the second line image 21 in the two-dimensional image.

[0044] In this case, the camera 50 needs to be calibrated in advance. If the camera 50 is calibrated, any position on the two-dimensional image can be obtained as a three-dimensional line of sight. Moreover, the positional relationship between the camera 50 and the slit light irradiated by the lighting device 40 needs to be calibrated in advance. The slit light irradiated by the lighting device 40 can be defined as a plane. The positional relationship between the plane and the camera 50 can be measured in advance and stored in the calibration information. By taking the intersection of the line of sight of any point on the first line image 11 and the second line image 21 detected on the two-dimensional image and the plane of the slit light, the three-dimensional position information of any point on the first line image 11 and the second line image 21 can be obtained. In this way, a three-dimensional line image on the first line image 11 and the second line image 21 can be obtained.

[0045] Therefore, the robot control device 30 can convert the offset amount and offset direction between the first line image 11 and the second line image 21 at the boundary B between the first base material 10 and the second base material 20 in the two-dimensional image into the three-dimensional offset amount and offset direction in the actual space. In addition, the robot control device 30 causes the robot 2 to move based on the correction amount calculated based on the converted three-dimensional offset (offset amount and offset direction).

[0046] As a result, the deviation between the first base material 10 and the second base material 20 can be corrected more accurately.

[0047] In addition, in the present embodiment, the robot control device 30 corrects the offset in the plate thickness direction between the surface of the first base material 10 and the surface of the second base material 20 based on the offset and the offset direction between the first line image 11 and the second line image 21 in the two-dimensional image. In addition, the inclination between the surface of the first base material 10 and the surface of the second base material 20 can also be corrected based on the inclination of the second line image 21 relative to the first line image 11.

[0048] For example, Figure 3 and Figure 4 As shown, when the surface of the second matrix 20 is arranged to be inclined relative to the surface of the first matrix 10, the second line image 21 is also formed to be inclined relative to the first line image 11 corresponding to the inclination between the surfaces of the first matrix 10 and the second matrix 20.

[0049] The robot control device 30 associates the angle formed by the first line image 11 and the second line image 21 with the inclination direction and inclination angle of the surface of the second base material 20 relative to the surface of the first base material 10 in advance based on the irradiation angle of the laser and the position information of the camera 50. In addition, the robot control device 30 can correct the inclination between the surface of the first base material 10 and the surface of the second base material 20 by moving the robot 2 based on the angle formed by the first line image 11 and the second line image 21.

[0050] In this case, the correction of the inclination of the second base material 20 by the robot 2 is preferably performed by, for example, placing the tip of the tool of the robot 2 at the edge of the second base material 20 adjacent to the boundary B, and rotating the second base material 20 around a coordinate axis extending along the edge of the second base material 20. Thus, the inclination of the second line image 21 can be made parallel to the first line image 11 without moving the tip position of the second line image 21 close to the boundary B.

[0051] Thereafter, by performing the above-described correction to make the first line image 11 and the second line image 21 coincide with each other, the first base material 10 and the second base material 20 can be accurately aligned, and more appropriate welding can be performed.

[0052] In addition, in the present embodiment, the first base material 10 and the second base material 20 are exemplified as flat plate-shaped base materials, but the present invention is not limited thereto and base materials of any shapes may be used.

[0053] In addition, in this embodiment, the offset between the first line image 11 and the second line image 21 in the two-dimensional image is calculated by the number of pixels, and the correction amount is calculated by multiplying the conversion coefficient by a positive decimal. However, instead, a constant obtained by multiplying the conversion coefficient by a coefficient greater than 1 may be used.

[0054] In this case, although the correction movement performed by the robot 2 is vibratory, it can sometimes also be positioned more quickly.

[0055] In addition, the present embodiment illustrates a robot system that performs butt welding on the first base material 10 and the second base material 20, but the present invention is not limited thereto, and any robot system may be used as long as the operation requires alignment of steps on the surfaces of adjacent workpieces.

[0056] Description of reference numerals:

[0057] 1Robotic system

[0058] 2. Robot

[0059] 10First base material (first workpiece)

[0060] 11 First Line Images

[0061] 20 Second base material (second workpiece)

[0062] 21 Second Line Image

[0063] 30Robot control device

[0064] 40 lighting fixtures

[0065] 50 cameras

[0066] B Boundary

Claims

1. A robot system, characterized in that: have: a robot that holds at least one of a first workpiece and a second workpiece that are adjacently arranged; an illumination device for irradiating slit-shaped light along a plane intersecting a boundary between the first workpiece and the second workpiece onto surfaces of the first workpiece and the second workpiece on both sides thereof; a camera that captures an image from a direction inclined relative to the plane, the image including a first line image of the light formed on the surface of the first workpiece and a second line image of the light formed on the surface of the second workpiece; as well as A robot control device moves the robot based on the offset amount and offset direction of the second line image in the image acquired by the camera relative to the first line image to correct the step between the surface of the first workpiece and the surface of the second workpiece.

2. The robot system according to claim 1, characterized in that: The camera acquires a two-dimensional image. The robot control device causes the robot to move by a correction amount corresponding to the number of pixels corresponding to the offset between the first line image and the second line image at the position of the boundary of the acquired two-dimensional image.

3. The robot system according to claim 2, characterized in that: The robot control device calculates the correction amount based on the number of pixels multiplied by a positive decimal.

4. The robot system according to claim 1, characterized in that: The lighting device and the camera have been pre-calibrated, The camera acquires a two-dimensional image. The robot control device calculates the three-dimensional offset between the first line image and the second line image at the position of the boundary of the two-dimensional image based on the first line image and the second line image in the acquired two-dimensional image, and causes the robot to move based on the correction amount calculated based on the calculated three-dimensional offset.

5. The robot system according to any one of claims 1 to 4, characterized in that: The robot control device repeats the correction until the offset between the first line image and the second line image after correction is smaller than a preset threshold value.

6. The robot system according to any one of claims 1 to 4, characterized in that: The robot control device corrects a tilt between the surface of the first workpiece and the surface of the second workpiece based on a tilt of the second line image relative to the first line image.

7. The robot system according to claim 5, characterized in that: The robot control device corrects a tilt between the surface of the first workpiece and the surface of the second workpiece based on a tilt of the second line image relative to the first line image.

Images