Control device and control method

Abstract

The invention provides a control device and a control method, which can greatly simplify the workload of a user in a process of creating a search program for generating a teaching point. A control device is provided with: a teaching unit for teaching a search start position and a search end position of a work line by means of a sensor; a program generation unit that generates a search program for specifying a teaching point corresponding to the position of the work line on the basis of the search start position and the search end position, and generates a work program including the teaching point on the basis of the execution result of the search program; and a specifying unit configured so as to be able to specify, when the search program is generated, whether or not to execute a tracking using a sensor for correcting the position of the robot during execution of the work program.

Description

Technical Field

[0001] The present disclosure relates to a control device and a control method. Background Art

[0002] A robot system is known, which comprises: a robot, a working tool such as a welding torch mounted on the robot, and a control device for controlling the robot. The control device drives the robot and the working tool according to a working program, and the user of the robot can teach the teaching points in advance in order to determine the position and posture of the robot during the operation. The working program is created according to the position of the teaching points.

[0003] The position of the teaching point may have a significant impact on the robot's work quality. For example, in a robot system that performs arc welding, the robot moves a welding torch mounted on a robot arm or the like along a work path determined by the teaching point. If the work path deviates from the desired path, the weld line also deviates from the desired path, and the processing accuracy is reduced.

[0004] In order to correct such deviation of the working path, the following control is known: a sensor is provided on a working tool such as a welding torch, and the working path is corrected while performing a welding operation. For example, the following control is known: a working path is generated in advance by specifying a starting point and an end point, and the position of the robot is moved along the working path, while the position for welding detected by the laser sensor is set as a teaching point (for example, see Patent Document 1).

[0005] In addition, there is known a teaching device that can easily teach the operation of a laser scanner and achieves shortening of the welding time of a robot (see, for example, Patent Document 2).

[0006] Furthermore, there is also known a robot that implements a technology for optimizing the movement path of the robot's end effector by tracking, and performs welding and other operations while moving a working tool along the detected line using a laser sensor to detect the position of the welding line (see, for example, Patent Document 3).

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 07-104831

[0010] Patent Document 2: Japanese Patent Application Publication No. 2006-247677

[0011] Patent Document 3: Japanese Patent Application Publication No. 2004-160578 Summary of the invention

[0012] Problems to be solved by the invention

[0013] In order to effectively suppress the position deviation of the robot's working path, it is expected to accurately generate / set teaching points. For example, the operator can set the teaching points by manually moving the robot to the desired position and posture, but in many cases, the teaching points require a high accuracy of less than 1 mm, which requires the operator to have high skills, and even skilled operators sometimes need a long working time.

[0014] As a method for generating teaching points, a method of setting a search point is conceived, which is used to determine the next teaching point along the work path based on a certain teaching point. In this method, an accurate work program can be generated for a certain workpiece. However, if the same work program is to be executed on other workpieces in a production line, etc., it is impossible to cope with the dimensional errors and deviations in the setting positions of each workpiece, making it difficult to perform specified operations such as welding with high accuracy.

[0015] As one of the measures to solve the above-mentioned problems, there is a method of generating a work program for each workpiece. However, in this method, the robot needs to perform two operations with respect to each workpiece, which results in a longer cycle time and a decrease in productivity.

[0016] Means for solving problems

[0017] One embodiment of the present disclosure is a control device that controls a robot having a sensor that can detect a work line of a workpiece, the control device comprising: a teaching unit that teaches a search start position and a search end position of the work line through the sensor; a program generation unit that generates a search program for determining a teaching point corresponding to the position of the work line based on the search start position and the search end position, and generates a work program including the teaching point based on the execution result of the search program; and a designation unit that is configured to designate whether to execute tracking using the sensor when generating the search program, the tracking being used to correct the position of the robot during the execution of the work program.

[0018] Another embodiment of the present disclosure is a control method for a robot having a sensor capable of detecting a work line of a workpiece, the control method comprising: teaching a search start position and a search end position of the work line by means of the sensor; generating a search program for determining a teaching point corresponding to the position of the work line based on the search start position and the search end position; generating a work program including the teaching point based on an execution result of the search program; and specifying whether to perform tracking using the sensor when generating the search program, the tracking being used to correct the position of the robot during the execution of the work program. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic structural diagram of a robot system according to an embodiment.

[0020] Figure 2 This is a schematic diagram for explaining the teaching of the search start point and the search end point using a sensor.

[0021] Figure 3 FIG. 1 is a diagram showing an example of teaching a search start point using a user interface.

[0022] Figure 4 FIG. 1 is a diagram showing an example of teaching a search end point using a user interface.

[0023] Figure 5 This is a schematic diagram for explaining the correction procedure by tracking.

[0024] Figure 6 This is a schematic diagram for explaining an example of setting the offset amount in teaching the search start point and the search end point.

[0025] Figure 7 This is a diagram showing an example of a user interface for setting various conditions in creating a search program.

[0026] Figure 8 This is a diagram showing an example of automatically generating a work program using a user interface.

[0027] Fig. 9 This is a flowchart showing an example of processing related to program generation. DETAILED DESCRIPTION

[0028] Figure 1 The robot system 10 includes at least one robot 12 , a robot control device 14 for controlling the robot 12 , and a teaching operation panel 16 connected to the robot control device 14 in a wireless or wired manner so as to be communicable therewith.

[0029] The robot 12 is, for example, an industrial multi-joint robot, and has a movable part (robot arm) 18; a working tool 22, which is mounted at the front end of the movable part 18 and is configured to perform a predetermined operation on a work object (workpiece) 20; and a sensor 24, which can detect the position of the working tool 22 at a working part (for example, a working line) of the workpiece 20. In the present embodiment, the working tool 22 is a welding torch, and the robot system 10 has a welding power source 26 that supplies current to the welding torch 22 according to a command from the robot control device 14. Thus, in the present embodiment, the working line includes a welding part of the workpiece, but the present disclosure is not limited thereto, and for example, the predetermined operation to be performed by the robot may be set as sealing, the working line includes a sealing part of the workpiece, and the working tool 22 may be set as a nozzle for spraying an adhesive, etc.

[0030] In the present embodiment, the sensor 24 is a laser scanner type three-dimensional sensor (laser sensor) having an emitting portion and a photographing sensor (CCD, CMOS, etc.), wherein the emitting portion emits light (e.g., a laser beam) according to a command from the robot control device 14, and the photographing sensor receives the light reflected by the workpiece and performs photoelectric conversion. The sensor 24 is mounted on the front end of the movable portion 18 or the welding torch 22 using a suitable mounting member (not shown), and the workpiece is continuously scanned along the work line to search for the work line. However, as a sensor, it is not limited to a laser sensor, and any sensor that can detect the work line can also be used, for example, a three-dimensional sensor can also be used. As a three-dimensional sensor, a TOF (Time of Flight) camera that captures a distance image by the light flight time method, or a stereo camera that detects a three-dimensional position by parallax captured by two two-dimensional cameras, etc. can be used.

[0031] The robot 12 is configured to be able to perform various processes and operations such as welding according to the instructions sent from the robot control device 14. The robot control device 14 has a processor and a storage unit (memory, etc.), and can control the robot 12 according to the operation program described later. In addition, in addition to the operation program for controlling the robot 12, the robot control device 14 can also generate / save the search program described later and execute the search program to control the sensor 24. That is, in this embodiment, the teaching operation panel 16 has a function as a teaching unit, the processor of the robot control device 14 has a function as a program generation unit, and the user interface described later has a function as a designation unit. However, the present disclosure is not limited to this, and for example, it can also be: a computer such as a personal computer (PC) 28 having a processor and a storage unit (memory, etc.) connected to the control device 14 in a wired or wireless manner generates each program, and the generated program is sent from the PC 28 to the control device 14.

[0032] The teaching operation panel 16 includes a receiving unit such as a keyboard or a touch panel capable of receiving various inputs from a user, and a display unit such as a display. The receiving unit and the display unit may constitute a user interface.

[0033] Figure 2 This is a diagram schematically illustrating welding as an example of the operation performed by the robot 12. Here, the shapes of two plate-shaped workpieces 20a and 20b having a predetermined shape are measured using a laser sensor 24 mounted on a welding torch 22, and teaching points are automatically generated based on the information obtained from the sensor 24, and arc welding is performed along a welding line 30.

[0034] Below, refer to Figure 3-Figure 9 , and explain the units and processes for generating search programs and operation programs. Figure 3 As illustrated, the user or operator of the robot 12 (hereinafter referred to as the user) can input various information for generating the search program and the operation program described later via the user interface (UI) 17 displayed on the display of the teaching operation panel 16. In other words, the UI 17 has the functions of a display unit that allows the user to visually recognize various information and a receiving unit that receives various inputs from the user. The UI 17 includes a robot display area 32 that can display a robot image corresponding to the position and posture of the actual robot 12; a timeline display area 34 that can display icons described later in a time series; and a menu display area 36 that can display each icon so that the user can select a desired icon.

[0035] First, in step S1( Fig. 9 ), the user of the robot 12 teaches the search start position (search start point) of the robot 12. Specifically, the user moves the robot 12 so that the sensor 24 is located at the search start point A (refer to Figure 2 ). Here, if Figure 3 As shown, an image corresponding to the position and posture of the actual robot 12 moved by the user can be displayed in the robot display area 32. After the user confirms that the robot 12 is located at the search start point A, the user selects an icon 38 (L) representing the search point from the menu display area 36, ​​and moves it to the timeline display area 34 by dragging and dropping. Then, the icon "L" is arranged at the left end of the timeline display area 34, thereby teaching the search start position.

[0036] Here, the search start position is different from the welding start position (operation start position). For example, in direct teaching, it is sometimes difficult to teach the welding start position due to interference between the robot and the workpiece. In this case, teaching becomes easier by using a search start position slightly away from the welding start position. However, if there are no constraints such as interference, the search start position and the welding start position may be the same position in the end. The same is true for the search end position. Although it is different from the welding end position (operation end position), it may be the same position in the end.

[0037] Next, the user selects icon 40 (start) indicating a search start command from menu display area 36, ​​and moves to timeline display area 34 by dragging and dropping. Then, in timeline display area 34, icon "start" is arranged on the right side of icon "L".

[0038] In the search start command, the user can set various parameters in the search program (step S2). For example, the search program may include at least one of information related to the search range of the sensor 24, information related to the output of the sensor 24, information related to the path of the sensor 24, and information related to the automatically generated operation program. For example, the user can input information about the posture change between each teaching point as information related to the path of the sensor 24. In addition, the user can also input information related to the automatically generated operation program, such as specifying the welding speed in the operation program.

[0039] Then, if Figure 4 As shown, the user teaches the search end position (search end point) of the robot 12 (step S3). Specifically, the user moves the robot 12 so that the sensor 24 is located at the search start point B (refer to FIG. 1 ) that can detect the welding end position or its vicinity. Figure 2 ). Here, the state of the actual robot 12 moved by the user is displayed in the robot display area 32. After the user confirms that the robot 12 is located at the search end point B, the user selects the icon 38 (L) representing the teaching point from the menu display area 36, ​​and moves it to the timeline display area 34 by dragging and dropping. Then, in the timeline display area 34, the icon "L" is arranged on the right side of the icon "Start", thereby teaching the search end position.

[0040] Next, the user selects the icon 42 (Stop) indicating the end of the search from the menu display area 36, ​​and moves it to the timeline display area 34 by dragging and dropping. Then, the icon "Stop" is arranged at the right end of the timeline display area 34.

[0041] Here, the user can set whether to execute a predetermined process when the operation program described later is executed (step S4). Figure 7As shown in FIG. 1 , when the user switches the menu display area 36 from "Programming" to "Details", a setting screen for the search program is displayed, and the user can specify (input) the validity / invalidity of various conditions. Examples of the above-mentioned predetermined processing include tracking, setting of offset, posture change between teaching points, etc. These processing are described below.

[0042] exist Figure 7 In the example, as shown by reference numeral 39, the user can set whether to perform tracking by the sensor 24 during the execution of the work program for a workpiece different from that during the execution of the search program (e.g., workpieces 20c and 20d). Here, if the setting is "enabled", workpiece tracking by the sensor 24 is performed during the execution of the work program, and the motion correction unit corrects the motion of the robot based on the tracking result.

[0043] Figure 5 2 is a diagram illustrating the movement of the tool 22 when the tool 22 is set to perform tracking during the execution of the work program. Figure 2 As shown, when a search program is executed on workpieces 20a and 20b to generate an operation program, when the operation program is used for the operation (welding, etc.) of workpieces 20a and 20b, tracking is basically not required. However, when the same operation program is performed on different workpieces 20c and 20d, even if the workpieces 20c and 20d are the same in specifications as the workpieces 20a and 20b, accurate operation may not be performed due to dimensional errors, setting errors, thermal deformation, etc. However, if it is set to track when the operation program is executed, the robot's motion path is corrected by tracking according to the position or dimensional error of the workpiece, so that high-precision operation can be performed. In addition, tracking only corrects the operation program, so the operation program itself only needs to be generated once at the start of production. Therefore, tracking has almost no effect on the productivity of the system as a whole including the robot.

[0044] exist Figure 7 In the example, as shown by reference numeral 43, the user can set conditions related to the offset when tracking from the work line 30. For example, the user can set which direction (the traveling direction, the direction perpendicular to the traveling direction, the direction in which the tool itself extends, etc.) related to the tool 22 is set to set the offset when tracking. Figure 6 As shown in the example, when the work program is executed on the workpieces 20a and 20b, the tool 22 moves along the offset work line 33 offset from the work line 30 by a set offset amount. For example, in arc welding, it is sometimes possible to perform high-quality welding by making the tool follow a line slightly offset from the work line rather than making the tool follow the work line itself. In such a case, such a work line offset function is very convenient.

[0045] exist Figure 7 In the example, as shown by reference numeral 45, the user can select / specify the purpose of the operation program to be generated. For example, when the user selects "arc", the operation program automatically teaches "welding start command" and "welding end command", so the convenience for the user is improved. On the other hand, if there is no specification, the operation program only contains the action statements of the robot.

[0046] exist Figure 7 In the figure, as shown by reference numeral 46, the user can set conditions related to the change of the tool posture. For example, when the above-mentioned tracking only corrects the position of the tool (that is, does not correct the posture of the tool), it is sometimes difficult to ensure the accuracy of the posture. In such a case, it is effective to reduce the distance between the teaching points in the interval where the tool posture changes more, and increase the distance between the teaching points in the interval where the posture changes less. Therefore, as Figure 7 As shown, the user can easily create the above-mentioned work program by setting the upper limit of the posture change between teaching points.

[0047] When the processing of S1-S4 is completed, the robot control device 14 or PC28, which is equivalent to the program generation unit, completes the creation of a search program for searching the sensor 24 (step S5). That is, the search program can be displayed as a series of icons configured / displayed in a time series in the timeline display area 34. In this way, the user can create a search program through visually and intuitively easy-to-understand operations via the teaching operating panel (UI), so even if the user is not a skilled person, the desired search program can be created in a short time through simple operations. In addition, in the present embodiment, the user teaches the search start point and the search end point by directly moving the robot by hand or the like (so-called direct teaching), but the present disclosure is not limited to this, and the robot can also be moved by, for example, jog operation. In addition, before the execution of the search program, the various conditions in step S4 are set.

[0048] In addition, in the search program, in addition to the search start point and the search end point, the user can also add any point. For example, in order to change the moving direction of the welding torch during laser irradiation, at least one intermediate point can be taught between the search start point and the search end point, and the movement of the welding torch is not limited to a straight line, for example, it can also move along an arc. Information related to these intermediate points can also be displayed as icons.

[0049] Next, the search program generated in step S5 is executed (step S6). Here, the workpiece is irradiated with a scanning laser from the sensor 24 in the interval from the search start position to the search end position, and at least one teaching point is generated in the interval. Thus, a work program including the teaching point is automatically generated (step S7). The search program can also be executed by the user operating through the UI 17.

[0050] In the search action, such as Figure 2 As shown, while the sensor 24 moves from the search start position A to the search end position B, the shapes of the workpieces 20a and 20b are detected, and the teaching points of the robot 12 are automatically generated based on the results. In this embodiment, the workpiece has a curved portion near the center, so the laser irradiation start point 54a corresponding to the start end of the weld line 30, the laser irradiation end point 54d corresponding to the end end of the weld line 30, and the teaching points 54b and 54c near the center are generated.

[0051] When the search is completed and a teaching point is generated, a work program including the generated teaching point is automatically generated. Figure 8 As shown in FIG. 1 , the operation procedure is displayed as a combination of icons 48 in the timeline display area 34. Here, the operation procedure 48 includes an icon 54a indicating the start of welding, an icon 54d indicating the end of welding, and icons 54b and 54c indicating the teaching points in the welding operation between them. These icons are displayed in a time series in the timeline display area 34. Figure 8 In the example, all icons 54a-54d are displayed, but icon 54a containing information related to the search start position, icon 54d containing information related to the search end position, and at least one of icons 54b and 54c containing information related to the midpoint between the search start position and the search end position may also be displayed.

[0052] The user can check / edit the automatically generated operation program via the UI 17 of the teaching operation panel 16. For example, if one of the icons 54a-54d in the timeline display area 34 is clicked, various icons including operation information and the like are displayed in the menu display area 36, ​​and the user can set and change various parameters in the operation program such as the position correction of the teaching point.

[0053] In addition, the setting of whether to perform the above-mentioned tracking is also reflected in the UI 17. Figure 8 In the example of FIG. 5 , the start command and the end command of the tracking are respectively displayed as icons 51 and 52. These icons can also be displayed in a timeline format together with the above-mentioned icons 54a-54d, which is very easy for the user to understand.

[0054] Once the creation of the operating program (and editing as needed) is completed, the robot is controlled according to the operating program (step S8). Here, the tracking and other processes set to be effective in step S4 are included as instructions in the operating program, so these processes are also executed (step S9). As a result, the robot can perform prescribed operations such as welding according to the automatically generated operating program.

[0055] According to the above-mentioned embodiment, the user's teaching and other operations in the search program creation for generating teaching points can be greatly simplified through visual operation / input via the UI. Therefore, even an unfamiliar user can create a desired search program in a short time through simple operations, and can also automatically generate appropriate teaching points (operation program) through the execution of the search program.

[0056] Explanation of symbols

[0057] 10 Robotic System

[0058] 12 Robot

[0059] 14 Robot control device

[0060] 16 Teaching operation panel

[0061] 17 User Interface

[0062] 18 Robotic Arm

[0063] 20 Workpieces

[0064] 22 Welding torch

[0065] 24 Sensors

[0066] 26 Welding power supply

[0067] 28PC

[0068] 30 lines

[0069] 32 Robot display area

[0070] 33 Offset line

[0071] 34 Timeline display area

[0072] 36 Menu display area

[0073] 38, 40, 42, 51, 52 icons

[0074] 48 Operating procedures

[0075] 54a-54d teaching points.

Claims

1. A control device for controlling a robot having a sensor capable of detecting a work line of a workpiece, characterized in that: The control device has: A teaching unit, which teaches the search start position and the search end position of the work line through the sensor; a program generating unit for generating a search program for determining a teaching point corresponding to the position of the work line based on the search start position and the search end position, and generating a work program including the teaching point based on an execution result of the search program; as well as A designation unit is configured to designate, when generating the search program, whether to execute tracking using the sensor for correcting the position of the robot during execution of the work program.

2. The control device according to claim 1, characterized in that: The designating unit is configured to be capable of designating an offset amount for shifting the work line during generation of the work program.

3. The control device according to claim 1, characterized in that: The designating unit is configured to be able to designate a use of the work program when generating the work program.

4. The control device according to claim 1, characterized in that: The designation unit is configured to be able to designate a condition related to a posture change of the robot during generation of the work program.

5. A method for controlling a robot having a sensor capable of detecting a work line of a workpiece, characterized in that: The control method comprises: Teaching the search start position and the search end position of the operation line by means of the sensor; generating a search program for determining a teaching point corresponding to the position of the work line according to the search start position and the search end position; generating a work program including the teaching point based on the execution result of the search program; and specifying whether to execute tracking using the sensor when generating the search program, the tracking being used to correct the position of the robot during the execution of the work program.

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