Teaching device

Abstract

The present invention provides a teaching device that can improve the efficiency of teaching operations to a welding robot. [Solution] The teaching device 3 includes a trajectory generation unit 311 that generates a welding robot's motion trajectory starting from a predetermined welding torch position, passing through a plurality of teaching points, and ending at a predetermined welding torch position, and a display control unit 312 that displays the generated motion trajectory superimposed on the welding target included in the image captured by the imaging unit 4, wherein the trajectory generation unit 311 generates one or more waypoints between adjacent teaching points.

Description

[[Technical Field]]

[0001] The present invention relates to a teaching device. [[Background Art]]

[0002] The following Patent Document 1 discloses an operation teaching system that teaches operations to a welding robot. In this operation teaching system, when performing operation teaching, the welding torch provided at the end effector of a manipulator is replaced with an imaging unit. Then, based on the position information of the welding locations generated based on the images captured by the imaging unit, and the position and posture information of the manipulator when the images are captured, an operation trajectory based on the position and posture of the manipulator required for welding the welding locations is generated, and the operation trajectories of the respective welding locations are combined to generate teaching data. [[Prior Art Documents]] [[Patent Documents]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Publication No. 2019-150930 [[Summary of the Invention]] [[Problems to be Solved by the Invention]]

[0004] Incidentally, in the operation teaching system of Patent Document 1, before performing operation teaching, an operation of drawing a line indicating a welding location to be an operation trajectory (welding line) on an object to be welded is performed. This operation is performed by an operator drawing the welding line on the object to be welded using a pen. Therefore, the operation takes time and effort, and the line drawn with the pen may remain on the surface of the object to be welded.

[0005] Accordingly, an object of the present invention is to provide a teaching device capable of improving the work efficiency of teaching operations to a welding robot. [[Means for Solving the Problems]]

[0006] A teaching device according to one aspect of the present invention includes a trajectory generation unit that generates a welding robot's motion trajectory starting from a predetermined welding torch position, passing through a plurality of teaching points, and ending at a predetermined welding torch position, and a display control unit that displays the generated motion trajectory superimposed on a welding target included in an image captured by an imaging unit, wherein the trajectory generation unit generates one or more waypoints between adjacent teaching points.

[0007] According to this embodiment, when an operator teaches multiple teaching points, the welding robot generates a motion trajectory that returns to the predetermined welding torch position via the multiple teaching points from a predetermined welding torch position. In doing so, one or more waypoints are added between adjacent teaching points to generate the motion trajectory, and the generated motion trajectory can be superimposed on the welding target included in the captured image. This reduces the effort required for the operator to generate the welding robot's motion trajectory.

[0008] In the above embodiment, teaching points may be taught by direct operation, where the operator moves and controls the welding robot in response to an external force applied to the welding robot.

[0009] According to this embodiment, the operator can teach multiple teaching points at desired positions while directly operating the welding robot.

[0010] In the above embodiment, the display control unit may visually differentiate the display of waypoints from that of teaching points so that waypoints are more prominent than teaching points.

[0011] According to this embodiment, in addition to the teaching points taught by the operator, waypoints generated by the teaching device can be displayed in a way that is easy for the operator to visually confirm.

[0012] In the above embodiment, when the trajectory generation unit generates intermediate points before and after an intermediate teaching point, which is a teaching point excluding the teaching points at the welding start position and welding end position, the distance between the generated intermediate points and the intermediate teaching point may be calculated based on the distance between the intermediate teaching point and another teaching point located adjacent to the intermediate teaching point on the front or back side of the intermediate teaching point, or based on the welding speed.

[0013] According to this embodiment, intermediate points generated before and after the intermediate teaching point can be generated at appropriate positions according to the size of the welding target and welding speed, without requiring extra effort from the operator.

[0014] In the above embodiment, when the trajectory generation unit generates an approach point generated before the welding start position or a retraction point generated after the welding end position, it may adjust the direction of movement of the welding torch so that the welding robot can move without interfering with an object when moving the welding torch from the approach point toward the teaching point which is the welding start position, or when moving the welding torch from the teaching point which is the welding end position toward the retraction point, and generate the approach point or retraction point.

[0015] According to this embodiment, approach points and retraction points can be generated at appropriate positions according to the shape of the object to be welded, without requiring extra effort from the operator.

[0016] In the above embodiment, the display control unit may visually differentiate the display of the operation trajectory caused by air cut, which moves the welding torch without generating an arc, from the display of operation trajectories other than those caused by air cut.

[0017] According to this embodiment, the operation trajectory of the welding section and the operation trajectory due to air cutting can be displayed in a way that is easy for the operator to visually distinguish.

[0018] In the above embodiment, when the trajectory generation unit generates an air cut motion trajectory, it may adjust the direction of movement of the welding torch so that the welding robot operating due to the air cut can move without interfering with an object.

[0019] According to this aspect, an operation trajectory that allows a welding robot operated via air cutting to move without interfering with an object can be generated without requiring labor from an operator.

[0020] In the above aspect, the trajectory generation unit may generate a via point at a position indicated by the operator on an image.

[0021] According to this aspect, a via point can be generated at any position specified by the operator.

[0022] In the above aspect, the trajectory generation unit may generate a number of via points set by the operator between teaching points.

[0023] According to this aspect, any number of via points specified by the operator can be generated between each pair of teaching points. Effects of the Invention

[0024] According to the present invention, a teaching device capable of improving the work efficiency of teaching operations to a welding robot can be provided. Brief Description of the Drawings

[0025] [Figure 1] It is a diagram illustrating an example of a schematic configuration of a robot teaching system including a teaching device according to an embodiment. [Figure 2] It is a schematic diagram for explaining teaching points provided on a workpiece. [Figure 3] It is a schematic diagram for explaining via points. [Figure 4] It is a schematic diagram showing an example of an operation trajectory displayed superimposed on a workpiece included in a captured image. Mode for Carrying Out the Invention

[0026] A preferred embodiment of the present invention will be described with reference to the attached drawings. In each drawing, components with the same reference numerals have the same or similar configuration. Also, since the drawings are schematic, the dimensions and proportions of each component may differ from those of the actual components.

[0027] Figure 1 is a diagram illustrating a schematic configuration of a robot teaching system 100 including a teaching device 3 according to an embodiment. The robot teaching system 100 includes, for example, a robot control device 1, a manipulator 2, a teaching device 3, an imaging unit 4, and a display unit 5. The imaging unit 4 and the display unit 5 may be included in the teaching device 3.

[0028] The robot control device 1 and the teaching device 3, the robot control device 1 and the manipulator 2, and the teaching device 3 and the imaging unit 4 and display unit 5 are connected by cables, wireless communication, or the like.

[0029] Manipulator 2 is a welding robot that performs arc welding on a workpiece (base material) to be welded according to the welding conditions set in the robot control device 1. Manipulator 2 has, for example, a multi-joint arm mounted on a base member fixed to the floor of a factory, and a welding torch connected to the tip of the multi-joint arm as one of the work tools.

[0030] Manipulator 2 is a collaborative robot designed for joint work with humans and can operate in response to external forces. The operator can also directly manipulate (direct teaching) the manipulator 2 by applying external force directly with their hand and moving it in response to that force. The welding robot according to the present invention includes both robots requiring safety fences that are not designed for human collaboration and collaborative robots designed for human collaboration.

[0031] The robot control device 1 is a control unit that controls the operation of the manipulator 2 according to preset welding conditions. The welding conditions include data items such as welding conditions, welding start position, welding end position, welding distance, welding torch position and orientation. The welding conditions also include data items such as welding current, welding voltage, welding speed, wire feeding speed and workpiece thickness.

[0032] The robot control device 1 includes, for example, a control unit 11, a storage unit 12, and a communication unit 13. The control unit 11 is a processor and controls the manipulator 2 by executing work programs and the like stored in the storage unit 12.

[0033] The memory unit 12 is a computer-readable recording medium that stores programs for realizing various functions of the robot control device 1 and various data used in those programs. The communication unit 13 is a communication interface that controls communication with the manipulator 2 and teaching device 3, which are connected via a network or the like.

[0034] The robot control device 1 may further include a welding power supply unit. The welding power supply unit supplies welding current, welding voltage, etc., to the manipulator 2 according to predetermined welding conditions in order to generate an arc between the tip of the welding wire and the workpiece. The welding power supply unit may be provided separately from the robot control device 1.

[0035] The teaching device 3 is a device that performs processing when an operator teaches the operation of the manipulator 2, and is, for example, a tablet-type teach pendant. The teaching device 3 includes, for example, a control unit 31, a storage unit 32, and a communication unit 33.

[0036] The control unit 31 is a processor that controls each part of the teaching device 3 by executing programs stored in the memory unit 32. The functions of the control unit 31 will be described later.

[0037] The memory unit 32 is a computer-readable recording medium that stores programs for realizing various functions of the teaching device 3 and various data used in those programs. The communication unit 33 is a communication interface that controls communication with the robot control device 1, imaging unit 4, and display unit 5, which are connected via a network.

[0038] The imaging unit 4 is, for example, a 3D camera equipped with a distance measurement sensor, and also functions as a 2D camera. It is preferable to position the imaging unit 4 in a location that can capture at least the workspace including the workpiece. The imaging unit 4 may also be provided in the teaching device 3.

[0039] A distance measuring sensor is a sensor capable of measuring the distance to an object. Examples of distance measuring sensors that can be used include LiDAR (Light Detection and Ranging) sensors, millimeter-wave sensors, and ultrasonic sensors.

[0040] Here, the imaging unit 4 does not necessarily need to be equipped with a distance measurement sensor; it may be equipped with a distance measurement sensor separately from the imaging unit 4, or it may be omitted. If the distance measurement sensor is omitted, it is preferable to calculate the 3D coordinate data corresponding to the object based on multiple images of the object taken from multiple different positions. In this case, a known 3D measurement method using stereo imaging can be used.

[0041] The display unit 5 is, for example, a display device having a touch panel, which displays images (2D and 3D) of the subject captured by the imaging unit 4 and accepts input such as operation instructions from the operator. The display unit 5 may also be provided in the teaching device 3.

[0042] As shown in Figure 1, the control unit 31 of the teaching device 3 includes, functionally, a trajectory generation unit 311 and a display control unit 312.

[0043] The trajectory generation unit 311 generates an operation trajectory of the manipulator 2, starting from a predetermined welding torch tip position, passing through multiple teaching points, and ending at the predetermined welding torch tip position.

[0044] It is preferable to register, for example, the tip position of the welding torch of the manipulator 2 included in the image captured by the imaging unit 4 as a predetermined welding torch tip position, and to use that registered position as the home position (origin position).

[0045] The teaching points are taught through direct operation, where the operator moves and controls the welding robot in response to the external force applied to the manipulator 2. This will be explained in detail with reference to Figure 2.

[0046] Figure 2 shows three teaching points Ta, Tb, and Tc. The three teaching points Ta, Tb, and Tc are located at both ends and corners of the weld line formed along the intersection of the bottom plate workpiece Wa and the L-shaped workpiece Wb. Specifically, teaching point Ta is located at the welding start position, teaching point Tb is located at the corner of the L-shape, and teaching point Tc is located at the welding end position. Here, teaching points other than those located at the welding start position and welding end position (for example, teaching point Tb) are also called intermediate teaching points.

[0047] The teaching points may be taught using a general teach pendant, or they may be set by detecting planes or intersections between planes from point cloud data or image data of the workpiece that can be identified by the coordinates of the robot coordinate system. In the latter case, it is preferable to place a marker (e.g., an AR marker) that is fixed in position relative to the manipulator 2 and can be identified by the coordinates of the robot coordinate system near the workpiece, and to photograph the workpiece and the marker with the imaging unit 4. This makes it possible to identify the position of the virtual model of the workpiece and manipulator 2 displayed on the screen along with the marker as the position in the robot coordinate system, based on the specific position of the marker (e.g., the corner or center of the marker).

[0048] The trajectory generation unit 311 in Figure 1 generates multiple waypoints other than the teaching point when generating the motion trajectory of the manipulator 2 that passes through the teaching point. This will be explained in detail with reference to Figure 3.

[0049] Figure 3 shows the following intermediate points: the start point Va and end point Vg generated at the home position; the approach point Vb generated in front of the teaching point Ta indicating the welding start position; the intermediate points Vc and Vd generated before and after the intermediate teaching point Tb at the corner; the retraction point Ve generated ahead of the teaching point Tc indicating the welding end position; and the intermediate point Vf generated between the retraction point Ve and the end point Vg.

[0050] Here, at the corner of the workpiece, it is necessary to change the orientation (forward or backward angle) of the welding torch from its basic orientation and move it to prevent the welding torch from colliding with the workpiece. Therefore, sections are provided before and after the intermediate teaching point Tb at the corner, and intermediate points Vc and Vd are provided at the start and end points of these sections, respectively.

[0051] In this case, the machine moves from teaching point Ta to intermediate point Vc in the same basic position as the welding start position, and from intermediate point Vd to teaching point Tc in the same basic position as the welding end position. Then, at intermediate teaching point Tb, the machine adopts an intermediate position between the basic position of the welding start position and the basic position of the welding end position.

[0052] The distance from waypoint Vc to intermediate teaching point Tb and the distance from intermediate teaching point Tb to waypoint Vd may be the same or different. For example, a specific distance such as 20 mm or 30 mm may be arbitrarily defined.

[0053] Furthermore, when generating waypoints Vc and Vd, the distance from waypoint Vc to intermediate teaching point Tb and the distance from intermediate teaching point Tb to waypoint Vd may be modified based on the distance between the teaching point Ta adjacent to the generated waypoint Vc and the intermediate teaching point Tb, and the distance between the intermediate teaching point Tb adjacent to the generated waypoint Vd and the teaching point Tc. For example, if the distance between adjacent teaching points is shorter than a predetermined distance, the distance may be shortened from the initial setting to match the degree to which it is shortened.

[0054] Furthermore, when generating waypoints Vc and Vd, the distance from waypoint Vc to intermediate teaching point Tb, and the distance from intermediate teaching point Tb to waypoint Vd may be changed based on the welding speed. For example, the faster the welding speed, the longer these distances may be.

[0055] Here, the section from teaching point Ta, which indicates the welding start position, to teaching point Tc, which indicates the welding end position, is the welding section in which an arc is generated and the welding torch is moved. On the other hand, the section of the movement trajectory from the start point Va to the end point Vg that excludes the welding section is the section in which the welding torch is moved without generating an arc, so-called air-cut (no-load movement) section.

[0056] The trajectory generation unit 311 has a function to adjust the direction of movement of the welding torch so that the manipulator 2, which is operated by the air cut, can move without interfering with an object when generating an operation trajectory caused by the air cut. This function is described below.

[0057] The positions of the approach point Vb and the retraction point Ve are predetermined based on the welding start and end positions. For example, the approach point Vb and the retraction point Ve are set at a specific position, for example, 50 mm away from the welding position in the longitudinal direction (tool Z direction) of the welding torch, from the teaching point Ta indicating the welding start position and the teaching point Tc indicating the welding end position.

[0058] When setting the approach point Vb and the retraction point Ve, if the manipulator 2 interferes with an object, the welding torch may be continued to be pulled in the longitudinal direction of the welding torch until the interference with the object is resolved, or the direction in which the welding torch is pulled may be changed to another direction. In this case, it is preferable to adjust the direction in which the welding torch is pulled so as to shorten the cycle time (travel time).

[0059] Whether manipulator 2 interferes with an object can be determined by simulating a virtual model of manipulator 2. A 3D model of manipulator 2 can be used as the virtual model of manipulator 2. Images, drawings, or real-life images may also be used as the virtual model.

[0060] When determining whether interference occurs, it is also possible to determine whether manipulator 2 interferes with an object by checking whether the 3D model of manipulator 2 comes into contact with (including overlapping with) the point cloud data acquired by the distance measurement sensor. In this case, if the 3D model comes into contact with the point cloud data, it is determined that manipulator 2 interferes with the object.

[0061] Furthermore, the trajectory generation unit 311 determines whether the manipulator 2 will interfere with an object when generating the trajectory from the start point Va to the approach point Vb, or when generating the trajectory from the escape point Ve to the end point Vg. If the manipulator 2 interferes with an object, it generates a new waypoint at a position where the manipulator 2 can avoid interference with the object. This will be explained in detail below.

[0062] When generating the motion trajectory from the starting point Va to the approach point Vb in Figure 3, the manipulator 2 does not interfere with the object, so the trajectory generation unit 311 does not generate any new waypoints. In this case, the trajectory generation unit 311 generates the motion trajectory from the starting point Va to the approach point Vb.

[0063] On the other hand, when generating the motion trajectory from the evacuation point Ve to the end point Vg in Figure 3, the manipulator 2 interferes with the workpiece Wb, so the trajectory generation unit 311 generates a new waypoint Vf. In this case, the trajectory generation unit 311 generates the motion trajectory from the evacuation point Ve to the waypoint Vf, and the motion trajectory from the waypoint Vf to the end point Vg.

[0064] In this case, when avoiding interference, the manipulator 2 and welding torch may be moved in the direction of the imaging unit 4 to eliminate the interference, and a new waypoint may be generated at the moved position. When the imaging unit 4 is imaging the manipulator 2, there is no object between the imaging unit 4 and the manipulator 2, so it becomes possible to increase the accuracy of eliminating the interference.

[0065] The display control unit 312 shown in Figure 1 overlays the motion trajectory generated by the trajectory generation unit 311 onto the workpiece included in the captured image. A detailed explanation will be given with reference to Figure 4.

[0066] Figure 4 shows an example of an image P captured by the imaging unit 4. The image P includes the bottom plate workpiece Wa, the L-shaped workpiece Wb, the manipulator 2, and the marker M. The manipulator 2 may be a virtual model of the manipulator 2 or an actual manipulator 2.

[0067] Furthermore, the captured image P displays the motion trajectory Lw of the welding section, which is generated in accordance with the weld line formed at the intersection of workpiece Wa and workpiece Wb, and the motion trajectory La, which is generated in accordance with the movement due to air cutting, superimposed on workpiece Wa and workpiece Wb.

[0068] The display control unit 312 may display the teaching points and waypoints together when displaying the motion trajectory Lw and motion trajectory La. In this case, it is preferable to make the display manner of the waypoints visually different from that of the teaching points so that the waypoints stand out more than the teaching points. The different display manner can include, for example, color, pattern, and shape. This makes it possible to display the waypoints generated by the trajectory generation unit 311 separately from the teaching points taught by the operator in a display manner that is easy for the operator to visually confirm.

[0069] Furthermore, it is preferable that the display control unit 312 visually differentiates the display manner of the air-cut operation trajectory La from the display manner of operation trajectories Lw other than the air-cut operation trajectory La. This makes it possible to display the operation trajectory Lw of the welding section and the operation trajectory La due to air cutting in a way that is easy for the operator to visually distinguish.

[0070] As described above, according to the teaching device 3 of the embodiment, when an operator teaches multiple teaching points, the device generates a motion trajectory of the manipulator 2 that returns to the home position of the welding torch via the multiple teaching points from the home position of the welding torch. At that time, it generates the motion trajectory by adding one or more waypoints between adjacent teaching points, and it is possible to display the generated motion trajectory superimposed on the workpiece included in the captured image. This reduces the effort required for the operator to generate the motion trajectory of the manipulator 2.

[0071] Therefore, according to the teaching device 3 of this embodiment, it is possible to improve the efficiency of teaching the manipulator 2 how to operate.

[0072] [Differentiation] It should be noted that the present invention is not limited to the embodiments described above, and can be implemented in various other forms without departing from the spirit of the invention. For this reason, the above embodiments are merely illustrative in all respects and should not be interpreted restrictively.

[0073] For example, in the embodiment described above, the trajectory generation unit 311 generates waypoints based on the home position and teaching points, but is not limited to this. Waypoints may be further generated at positions pointed out (e.g., tapped) by the operator on the captured image. Alternatively, waypoints displayed on the captured image may be made movable by specifying them (e.g., by dragging).

[0074] Furthermore, in the embodiment described above, the trajectory generation unit 311 generates one waypoint between each teaching point, but is not limited to this. The number of waypoints generated between each teaching point may be arbitrarily set by the operator. For example, the position may be recorded each time the angle of each axis of the manipulator 2 changes by a predetermined angle (e.g., 5 degrees), unnecessary positions may be deleted as much as possible within a range that allows the welding torch's posture to change smoothly, and the remaining positions may be generated as waypoints.

[0075] When generating multiple waypoints between teaching points, the degree of change in the welding torch's orientation may be increased for waypoints located closer to intermediate teaching points in the corner helix. [Explanation of Symbols]

[0076] 1...Robot control device, 2...Manipulator, 3...Teaching device, 4...Imaging unit, 5...Display unit, 11...Control unit, 12...Storage unit, 13...Communication unit, 31...Control unit, 32...Storage unit, 33...Communication unit, 100...Robot teaching system, 311...Trajectory generation unit, 312...Display control unit

Claims

1. A trajectory generation unit generates a welding robot's motion trajectory starting from a predetermined welding torch position, passing through multiple teaching points, and ending at the predetermined welding torch position. A display control unit that overlays the generated motion trajectory onto the welding target included in the image captured by the imaging unit, Equipped with, The trajectory generation unit generates one or more waypoints between adjacent teaching points. Teaching device.

2. The teaching points are taught by direct operation, in which the operator moves and controls the welding robot in response to the external force applied to the welding robot. The teaching device according to claim 1.

3. The display control unit makes the display of the waypoints visually different from the display of the teaching points so that the waypoints are more prominent than the teaching points. The teaching device according to claim 1.

4. The trajectory generation unit generates intermediate points before and after the intermediate teaching point, which is the teaching point excluding the teaching points at the welding start position and welding end position, and calculates the distance between the generated intermediate points and the intermediate teaching point based on the distance between the intermediate teaching point and another teaching point located adjacent to or ahead of the intermediate teaching point, or the welding speed. The teaching device according to claim 1.

5. When the trajectory generation unit generates an approach point generated before the welding start position or a retraction point generated after the welding end position, it adjusts the direction of movement of the welding torch so that the welding robot can move without interfering with an object when moving the welding torch from the approach point toward the teaching point which is the welding start position, or when moving the welding torch from the teaching point which is the welding end position toward the retraction point, and generates the approach point or the retraction point. The teaching device according to claim 1.

6. The display control unit makes the display mode of the operation trajectory caused by air cut, which moves the welding torch without generating an arc, visually different from the display mode of the operation trajectory other than the operation trajectory caused by air cut. The teaching device according to claim 1.

7. When generating the motion trajectory due to the air cut, the trajectory generation unit adjusts the direction of movement of the welding torch so that the welding robot operating due to the air cut can move without interfering with an object. The teaching device according to claim 6.

8. The trajectory generation unit generates the waypoints at the positions indicated by the operator on the image. The teaching device according to claim 1.

9. The trajectory generation unit generates a number of waypoints set by the operator between the teaching points. The teaching device according to claim 1.

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