Method of controlling robot and robot system

Abstract

The invention relates to a method for controlling a robot and a robot system, and provides a technology capable of teaching with high precision while accurately measuring a distance. A method of controlling a robot includes: (a) positioning a distance measuring device provided on a movable stage at a distance measuring position for measuring a distance to a workpiece by setting the movable stage provided on a tip portion of a robot arm at a first position; (b) in a state where the movable stage is set at the first position, performing distance measurement by the distance measuring device and performing teaching using the result of the distance measurement; (c) positioning an end effector provided on the movable stage at a work position for performing robotic work on the workpiece by setting the movable stage at a second position different from the first position; and (d) in a state where the movable stage is set at the second position, performing a robotic work on the workpiece.

Description

Technical Field

[0001] The present disclosure relates to a method for controlling a robot and a robot system. Background Art

[0002] In Patent Document 1, a painting robot is disclosed that paints by spraying paint from a nozzle onto a vehicle or vehicle part to be painted. In this prior art, a distance measurement unit that measures the distance between the painting part of the object to be painted and the nozzle spraying surface of the head is used, and control is performed in such a way that paint is sprayed from the nozzles within a specified range of the distance measured by the distance measurement unit.

[0003] Patent Document 1: International Publication No. 2021 / 255896

[0004] However, in the above prior art, since there is a physical distance between the head and the distance measurement unit, when the surface of the object is a curved surface, there is a problem that the distance between the object and the head cannot be accurately measured. In addition, when teaching is performed while measuring the distance, there is a problem that accurate teaching cannot be performed. Summary of the Invention

[0005] According to a first aspect of the present disclosure, a method for controlling a robot is provided. The method includes: (a) a step of positioning a distance measurement device provided on a movable stage provided at the front end of a robotic arm at a distance measurement position for measuring the distance to a workpiece by setting the movable stage at a first position; (b) a step of performing distance measurement by the distance measurement device and performing teaching using the result of the distance measurement while the movable stage is set at the first position; (c) a step of positioning an end effector provided on the movable stage at a work position for performing a robot operation on the workpiece by setting the movable stage at a second position different from the first position; and (d) a step of performing the robot operation on the workpiece while the movable stage is set at the second position.

[0006] According to a second aspect of the present disclosure, a robot system is provided. The robot system includes: a robot including a robotic arm; a movable stage provided at a front end portion of the robotic arm; a distance measuring device provided on the movable stage; an end effector provided on the movable stage; and a control device. The control device is configured to perform the following processes: (a) a process of positioning the distance measuring device at a distance measuring position for measuring the distance to a workpiece by setting the movable stage at a first position; (b) a process of performing distance measurement by the distance measuring device and executing teaching using the result of the distance measurement in a state where the movable stage is set at the first position; (c) a process of positioning the end effector at a work position for performing a robot operation on the workpiece by setting the movable stage at a second position different from the first position; and (d) a process of performing the robot operation on the workpiece in a state where the movable stage is set at the second position. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 FIG. is an explanatory diagram showing the structure of the robot system in the embodiment.

[0008] Figure 2 FIG. is a functional block diagram of the information processing device in the embodiment.

[0009] Figure 3 FIG. is an explanatory diagram showing the states at the time of teaching execution and robot operation execution.

[0010] Figure 4 FIG. is an explanatory diagram showing an enlarged state at the time of teaching execution.

[0011] Figure 5 FIG. is a flowchart showing the processing steps of teaching and robot operation.

[0012] Figure 6 FIG. is an explanatory diagram showing an example of an operation screen for teaching processing.

[0013] REFERENCE MARK DESCRIPTION

[0014] 10: Robot system; 100: Robot; 110: Base; 120: Robotic arm; 122: Front end portion; 200: Robot controller; 300: Information processing device; 310: Processor; 311: Teaching processing unit; 312: Robot operation execution unit; 320: Memory; 330: Interface circuit; 340: Input device; 350: Display device; 400: Teach pendant; 500: Stand; 610: Moving device; 612: Movable stage; 620: Inkjet device; 622: Inkjet head; 630: Distance measuring device. DETAILED DESCRIPTION OF THE EMBODIMENT

[0015] Figure 1 This is an explanatory diagram showing an example of a robot system in one embodiment. The robot system 10 includes a robot 100, a robot controller 200 that controls the robot 100, an information processing device 300, a teaching pendant 400, and a stage 500 on which a workpiece WK is placed. The information processing device 300 is, for example, a personal computer.

[0016] In Figure 1 three axes X, Y, and Z of an orthogonal coordinate system defining a three-dimensional space are depicted. The X-axis and the Y-axis are axes in the horizontal direction, and the Z-axis is an axis in the vertical direction. In this example, the XYZ coordinate system is a robot coordinate system with a reference point preset in the robot 100 as the origin.

[0017] The robot 100 includes a base 110 and a robotic arm 120. A moving device 610 including a movable stage 612 is mounted on the front end portion 122 of the robotic arm 120. An inkjet device 620 and a distance measuring device 630 as end effectors are provided on the movable stage 612. It should be noted that the inkjet device 620 and the distance measuring device 630 may also be fixed to the movable stage 612 via mounting auxiliary members.

[0018] As the moving device 610, for example, a single-axis worktable capable of moving the movable stage 612 in one axial direction can be used. Alternatively, a multi-axis worktable capable of moving the movable stage 612 in two or more directions can also be used. In the present embodiment, a single-axis worktable is used as the moving device 610. The movable stage 612 is sometimes referred to as a "slider" or a "table". As a driving method of the moving device 610, a driving method using an electromagnetic motor and a ball screw can be used. Alternatively, an electromagnetic driving method or an ultrasonic driving method can also be used. In the case of using a ball screw mechanism, if a reduction mechanism is used in combination, a large load can be tolerated. Although the electromagnetic driving method or the ultrasonic driving method of the worktable has a small force, it can be formed into a small and lightweight structure. In addition, as in the ultrasonic driving method, in the method of driving the movable stage 612 using a piezoelectric actuator, the movable stage 612 can be moved without generating large vibrations in the end effector.

[0019] The inkjet device 620 has an inkjet head 622. The inkjet head 622 performs printing by ejecting ink onto a printing area on the surface of the workpiece WK. Preferably, the inkjet head 622 can eject a variety of inks to perform color printing. The printing area on the surface of the workpiece WK may include a curved surface portion instead of a flat surface. As can be understood from this description, the robot system 10 of the present embodiment functions as a DTS (Direct To Shape) printing device for printing on the surface of a three-dimensional object.

[0020] As an end effector, any device or mechanism other than the inkjet device 620 can be used. For example, as an end effector, a coating device for applying a liquid agent, a welding device for welding, a robot for precision assembly, etc. can be used.

[0021] The distance measuring device 630 is a device that measures the distance to the surface of the workpiece WK. As the distance measuring device 630, for example, a laser displacement meter, an infrared sensor, an ultrasonic sensor, a stereo camera, etc. can be used. In the present embodiment, a laser displacement meter is used as the distance measuring device 630.

[0022] Near the front end of the robotic arm 120, a TCP (Tool CenterPoint) that is the control point of the robot 100 is set. In Figure 1 the example, the TCP is set near the surface of the inkjet head 622. It should be noted that the control point TCP can be set at any position.

[0023] The robotic arm 120 is sequentially connected by six joints J1 to J6. Among these joints J1 to J6, three joints J2, J3, and J5 are bending joints, and the other three joints J1, J4, and J6 are twisting joints. In the present embodiment, a six-axis robot is illustrated, but a robot having any robotic arm mechanism with a plurality of joints can also be used. In addition, the robot 100 of the present embodiment is a vertical multi-joint robot, but a horizontal multi-joint robot can also be used.

[0024] The teaching process of the robot 100 is performed using the information processing device 300 or the teach pendant 400. In the embodiments described below, the information processing device 300 is used to execute the teaching process. The function of the "control device" of the present disclosure is implemented using at least a part of the robot controller 200, the information processing device 300, and the teach pendant 400.

[0025] Figure 2 is a block diagram showing the functions of the information processing device 300. The information processing device 300 has a processor 310, a memory 320, and an interface circuit 330. An input device 340 and a display device 350 are connected to the interface circuit 330. In addition, the robot controller 200 is also connected. The robot 100, the teach pendant 400, the mobile device 610, the inkjet device 620, and the distance measuring device 630 are connected to the information processing device 300 via the robot controller 200. However, a part of them can also be directly connected to the information processing device 300.

[0026] The processor 310 has functions as a teaching processing unit 311 and a robot operation execution unit 312. The teaching processing unit 311 performs teaching using the result of distance measurement by the distance measuring device 630, thereby creating a robot control program RP. The robot operation execution unit 312 uses the robot control program RP to execute robot operations. In the present embodiment, the robot operation is an operation of printing on the workpiece WK using the inkjet device 620.

[0027] The functions of the teaching processing unit 311 and the robot operation execution unit 312 are respectively implemented by the processor 310 executing computer programs stored in the memory 320. However, part or all of the functions of the teaching processing unit 311 and the robot operation execution unit 312 can also be implemented by hardware circuits.

[0028] The robot control program RP generated by teaching processing is stored in the memory 320. The robot control program RP is composed of a plurality of commands for operating the robot 100 and includes the coordinate values of a plurality of teaching points.

[0029] Figure 3 It is an explanatory diagram showing the states during teaching execution and robot operation execution. During teaching execution, the movable stage 612 is moved by the teaching processing unit 311 and set at the first position, and the distance measuring device 630 is positioned at the distance measuring position for measuring the distance to the workpiece WK. The movable stage 612 can move left and right along the moving direction Dm as one axial direction Figure 3 The distance measuring position of the distance measuring device 630 is the position of the operation target position Pw where the imaginary straight line extending in the measuring direction Ds of the distance measuring device 630 passes through the surface of the workpiece WK. The measuring direction Ds of the distance measuring device 630 is the direction from the reference position Ps of the distance measuring device 630 toward the measurement object. For example, when a laser displacement meter is used as the distance measuring device 630, the reference position Ps of the distance measuring device 630 corresponds to the position of the light receiving sensor. In a state where the movable stage 612 is set at such a first position, teaching processing is performed using the result of distance measurement by the distance measuring device 630.

[0030] During the execution of the robot operation, the robot operation execution unit 312 positions the inkjet device 620, which is the end effector, at the operation position for performing the robot operation on the workpiece WK by moving the movable stage 612 from the first position to the second position. The operation position of the inkjet device 620 is the position where a virtual straight line extending in the reference direction De of the inkjet device 620 passes through the operation target position Pw on the surface of the workpiece WK. The reference direction De of the inkjet device 620 is the direction from the reference position Pe of the inkjet device 620 toward the operation target position Pw of the workpiece WK. This reference direction De is parallel to the measurement direction Ds of the distance measurement device 630. The reference position Pe of the inkjet device 620 is the position that serves as the reference for the operation of the inkjet device 620. Specifically, the reference position Pe of the inkjet device 620 corresponds to the center position of the surface of the inkjet head 622. The reference direction De of the inkjet device 620 is parallel to the measurement direction Ds of the distance measurement device 630. In the present embodiment, the operation target position Pw of the workpiece WK corresponds to the center position of the inkjet area where the ink is simultaneously ejected by the inkjet head 622. The printing as the robot operation is performed in a state where the movable stage 612 is set at such a second position.

[0031] As can be understood from Figure 3 As can be understood, the moving direction Dm of the movable stage 612 is set to a direction perpendicular to the reference direction De in which the inkjet device 620 faces the workpiece WK during the execution of the robot operation. During teaching, the movable stage 612 is set at the first position to position the distance measurement device 630 at the distance measurement position for measuring the distance to the workpiece WK. During the robot operation, the inkjet device 620 is positioned at the operation position for operating on the workpiece WK by moving the movable stage 612 from the first position to the second position. As a result, distance measurement can be accurately performed while teaching can be performed with high precision. In addition, teaching can be performed while moving the robotic arm 120 along the same trajectory as the movement trajectory TR of the robotic arm 120 during the robot operation.

[0032] The moving direction Dm of the movable stage 612 is preferably set to a direction orthogonal or parallel to the rotational axis direction of the rotary joint J6 located at the outermost end of the robotic arm 120. In this way, regardless of the joint displacement of the rotary joint J6, the inkjet device 620 and the distance measurement device 630 can be easily positioned at their respective appropriate positions.

[0033] Figure 4 is an explanatory diagram showing an enlarged state during the execution of teaching. The origin position Pref of the distance measurement device 630 is the position where the distance measurement value Ls output from the distance measurement device 630 is 0, and can be initialized to any position. In Figure 4In the example, the origin position Pref of the distance measuring device 630 is initialized to a height equal to the surface position of the workpiece WK. In addition, the distance Le from the reference position Pe of the inkjet device 620 to the surface of the workpiece WK is equal to the set distance G suitable for inkjet. In other words, the distance measuring device 630 performs zero point correction so that the measured distance value Ls thereof shows the difference between the set distance G suitable for inkjet and the actual distance Le. The set distance G suitable for inkjet is a so-called head gap, and an appropriate value is preset according to the type of the inkjet device 620 and the attributes of the printing object. Usually, the set distance between the end effector and the workpiece is set to a value corresponding to the type of the end effector. It should be noted that when the origin position Pref of the distance measuring device 630 is initialized to a position with a height different from Figure 4 that, the distance Le from the inkjet device 620 to the workpiece WK during robot operation can also be calculated based on the measured distance value Ls from the distance measuring device 630 to the workpiece WK.

[0034] As can be understood from the above description, preferably, the position of the teach point set in the teaching is determined such that the distance Le from the inkjet device 620 to the workpiece WK calculated based on the measured distance value Ls from the distance measuring device 630 to the workpiece WK is equal to the set distance G suitable for robot operation. In this way, teaching can be performed such that the distance Le between the inkjet device 620 and the workpiece WK during robot operation becomes the desired set distance G.

[0035] Figure 5 is a flowchart showing the processing steps of teaching and robot operation. In step S11, the teaching processing unit 311 positions the movable stage 612 at the first position for teaching. As a result, as Figure 3 shown, the distance measuring device 630 is positioned at the distance measuring position for measuring the distance to the workpiece WK.

[0036] Steps S12 to S14 are executed by the teaching processing unit 311. In step S12, the teaching processing unit 311 performs teaching processing to set a plurality of teach points.

[0037] Figure 6 is an explanatory diagram showing an example of the operation screen for teaching processing. The teaching processing window W10 includes a robot selection field RF for selecting the robot type, a program selection field PF for specifying the program name of the action program, a confirmation mode execution button EB, a confirmation mode stop button SB, a robot display window W11, and a jogging operation window W12.

[0038] The robot display window W11 is a screen that displays a simulated image of the robot 100. As the simulated image, either a three-dimensional image or a two-dimensional image can be selectively displayed. In a state where the three-dimensional image of the robot 100 is displayed, the user can arbitrarily change the direction of the viewing point and the display magnification of the image by operating the mouse within the robot display window W11. In this example, a simulated image of the workpiece WK is also arranged within the robot display window W11. However, the robot display window W11 can also be omitted.

[0039] The jog operation window W12 is a screen for the user to input jog operations. The jog operation window W12 includes: a coordinate system selection field CF for selecting a coordinate system, a coordinate value field VF1 for specifying six coordinate values corresponding to the selected coordinate system, a head gap display section HG for displaying the head gap, a teaching point field TF for specifying a teaching point to be edited, a teaching point setting button B1, and an end button B2. To the right of the coordinate value field VF1, an increment / decrement button CB1 for increasing or decreasing the coordinate value is arranged. To the right of the teaching point field TF, an increment / decrement button CB2 for increasing or decreasing the number of the teaching point is arranged.

[0040] In the head gap display section HG, a distance index value showing the distance Le between the inkjet head 622 and the workpiece WK described in Figure 4 is displayed. As the distance index value, for example, the difference between the set distance G of the head gap and the actual distance Le, that is, the head gap error, is displayed. As described above, the distance measuring device 630 performs zero correction so that its distance measurement value Ls shows the difference between the set distance G of the head gap and the actual distance Le. Therefore, the distance measurement value Ls is displayed in the head gap display section HG. Alternatively, as the distance index value, the value of the distance Le between the inkjet head 622 and the workpiece WK can also be displayed. Thus, during teaching, if a distance index value showing the distance Le between the inkjet head 622 and the workpiece WK is displayed on the control device, the teaching point can be set while confirming whether the head gap is an appropriate value. However, the display of the distance index value can also be omitted.

[0041] It should be noted that in step S12, the positions of the respective teaching points may not be set such that the head gap is equal to the set distance G, and the positions of the respective teaching points can also be temporarily set. In this case, in the following steps S13 and S14, the positions of the respective teaching points are corrected.

[0042] In step S13, the teaching processing unit 311 moves the robotic arm 120 to track a plurality of teaching points and obtains the results of distance measurement of the plurality of teaching points. In this step S13, the movable stage 612 is located at Figure 3 and Figure 4 the positions during teaching execution shown in, and performs distance measurement using the distance measuring device 630.

[0043] In step S14, the teaching processing unit 311 corrects the positions of the respective teaching points using the results of distance measurement. Specifically, as described in Figure 4 , the positions of the teaching points are corrected such that the distance Le from the inkjet device 620 to the workpiece WK calculated based on the distance measurement value Ls from the distance measuring device 630 to the workpiece WK is equal to the set distance G suitable for the robot operation. Thus, by correcting the plurality of temporarily set teaching points, the distance between the inkjet device 620 and the workpiece WK during the robot operation can be made to conform to the desired set distance G. The correction of the teaching points in step S14 can be performed multiple times by tracking the actions of the plurality of teaching points and gradually implementing them. That is, it is also possible to finally make the distance between the inkjet device 620 and the workpiece WK during the robot operation equal to the desired set distance G while slightly correcting the positions of the teaching points in one action.

[0044] Note that when the distance from the distance measuring device 630 to the workpiece WK is set to an appropriate value in step S12, steps S13 and S14 can be omitted.

[0045] When the teaching process ends, it proceeds to Figure 5 step S15, where the robot operation execution unit 312 positions the movable stage 612 at the second position for robot operation. As a result, as Figure 3 shown, the inkjet device 620 is positioned at the operation position for printing on the workpiece WK.

[0046] In step S16, the robot operation execution unit 312 performs a robot operation. In the present embodiment, printing is performed on the surface of the workpiece WK. When performing the printing, as Figure 3 described, the inkjet device 620 is positioned at the operation position for inkjetting on the workpiece WK. Additionally, it is preferable that during the robot operation, the movable stage 612 is not moved, and printing is performed based on the movement of the robotic arm 120 and the inkjet device 620 while the inkjet device 620 is fixed at the operation position.

[0047] As described above, during the teaching execution, the movable stage 612 is set at the first position to position the distance measuring device 630 at the distance measuring position for measuring the distance to the workpiece WK. Additionally, during the robot operation execution, by setting the movable stage 612 at the second position different from the first position, the inkjet device 620 as the end effector is positioned at the operation position for the robot operation on the workpiece WK. Therefore, distance measurement can be accurately performed while teaching is carried out with high precision. Additionally, it is possible to perform teaching while moving the robotic arm 120 along the same trajectory as the movement trajectory of the robotic arm 120 during the robot operation.

[0048] Other ways

[0049] The present disclosure is not limited to the above-described embodiments, and can be implemented in various ways without departing from its gist. For example, the present disclosure can also be implemented by the following aspects. The technical features in the above-described embodiments corresponding to the technical features in each of the following-described aspects can be appropriately replaced and combined in order to solve part or all of the technical problems of the present disclosure or to achieve part or all of the effects of the present disclosure. In addition, if the technical feature is not described as an essential feature in this specification, it can be appropriately deleted.

[0050] (1) According to a first aspect of the present disclosure, a method for controlling a robot is provided. The method includes: (a) a process of positioning a distance measuring device provided on a movable stage provided at the front end of a robotic arm at a distance measuring position for measuring the distance to a workpiece by setting the movable stage at a first position; (b) a process of performing distance measurement by the distance measuring device and performing teaching using the result of the distance measurement in a state where the movable stage is set at the first position; (c) a process of positioning an end effector provided on the movable stage at a work position for performing a robot operation on the workpiece by setting the movable stage at a second position different from the first position; and (d) a process of performing the robot operation on the workpiece in a state where the movable stage is set at the second position.

[0051] According to this method, it is possible to perform teaching with high precision while accurately performing distance measurement. In addition, it is possible to perform teaching while moving the robotic arm along the same trajectory as the movement trajectory of the robotic arm during robot operation.

[0052] (2) In the above method, it may also be that when the direction of the end effector toward the workpiece is used as the reference direction of the end effector during the robot operation, the movable stage is configured to move in a direction perpendicular to the reference direction of the end effector.

[0053] According to this method, it is possible to appropriately set the distance measuring position of the distance measuring device during teaching and the work position of the end effector during robot operation execution, respectively.

[0054] (3) In the above method, it may also be that the position of the teaching point set in the teaching is determined such that the distance from the end effector to the workpiece during the robot operation calculated based on the measured value of the distance from the distance measuring device to the workpiece is equal to a set distance suitable for the robot operation.

[0055] According to this method, teaching can be performed in such a way that the distance between the end effector and the workpiece during the operation of the robot becomes a desired set distance.

[0056] (4) In the above method, it may also be that the process (b) includes: (b1) a process of temporarily setting a plurality of teaching points; (b2) a process of moving the robotic arm to track the plurality of teaching points and obtaining the result of the distance measurement performed by the distance measuring device at the positions of the plurality of teaching points; and (b3) a process of correcting the positions of the respective teaching points using the results of the distance measurement of the plurality of teaching points so that the distance during the robot operation from the end effector at each teaching point to the workpiece is equal to the set distance.

[0057] According to this method, by correcting a plurality of temporarily set teaching points, the distance between the end effector and the workpiece during the operation of the robot can be made to conform to the desired set distance.

[0058] (5) In the above method, it may also be that the end effector includes an inkjet head, and the robot operation is a process of performing printing on a printing area including a curved surface portion on the surface of the workpiece using the inkjet head.

[0059] According to this method, direct forming printing can be accurately performed.

[0060] (6) In the above method, it may also be that the movable stage is driven by a piezoelectric actuator.

[0061] According to this method, the movable stage can be moved without causing a large vibration in the end effector.

[0062] (7) According to the second aspect of the present disclosure, a robot system is provided. The robot system includes: a robot including a robotic arm; a movable stage provided at the front end of the robotic arm; a distance measuring device provided on the movable stage; an end effector provided on the movable stage; and a control device. The control device is configured to perform the following processes: (a) a process of positioning the distance measuring device at a distance measuring position for measuring the distance to the workpiece by setting the movable stage at a first position; (b) a process of performing distance measurement by the distance measuring device and performing teaching using the result of the distance measurement in a state where the movable stage is set at the first position; (c) a process of positioning the end effector at a working position for performing a robot operation on the workpiece by setting the movable stage at a second position different from the first position; and (d) a process of performing the robot operation on the workpiece in a state where the movable stage is set at the second position.

[0063] The present disclosure can also be implemented in various ways other than those described above. For example, it can be implemented by a robot system including a robot and a robot control device, a computer program for implementing the functions of the robot control device, a non-transitory storage medium recording the computer program, and the like.

Claims

1. A method for controlling a robot, characterized in that, comprises the following steps: (a) a step of positioning a distance measuring device provided on a movable stage provided at the front end of a robotic arm at a distance measuring position for measuring the distance to a workpiece by setting the movable stage at a first position; (b) a step of performing distance measurement by the distance measuring device and performing teaching using the result of the distance measurement while the movable stage is set at the first position; (c) a step of positioning an end effector provided on the movable stage at a working position for performing robotic operations on the workpiece by setting the movable stage at a second position different from the first position; and (d) a step of performing the robotic operation on the workpiece while the movable stage is set at the second position.

2. The method according to claim 1, wherein when the direction of the end effector toward the workpiece is taken as the reference direction of the end effector during the performance of the robotic operation, the movable stage is configured to move in a direction perpendicular to the reference direction of the end effector.

3. The method according to claim 1, wherein the position of the teaching point set in the teaching is determined such that the distance during the robotic operation from the end effector to the workpiece calculated based on the measured value of the distance from the distance measuring device to the workpiece is equal to a set distance suitable for the robotic operation.

4. The method according to claim 3, wherein the step (b) includes: (b1) a step of temporarily setting a plurality of teaching points; (b2) a step of causing the robotic arm to move to track the plurality of teaching points and obtaining the result of the distance measurement performed by the distance measuring device at the positions of the plurality of teaching points; and (b3) a step of correcting the positions of the respective teaching points using the results of the distance measurements of the plurality of teaching points so that the distance during the robotic operation from the end effector of each teaching point to the workpiece is equal to the set distance.

5. The method according to claim 1, wherein the end effector includes an inkjet head, and the robotic operation is a process of performing printing on a printing area including a curved surface portion on the surface of the workpiece using the inkjet head.

6. The method according to claim 1, wherein the movable stage is driven by a piezoelectric actuator.

7. A robot system, characterized in that, comprising: a robot including a robotic arm; a movable stage provided at the front end of the robotic arm; a distance measuring device provided on the movable stage; an end effector provided on the movable stage; and a control device, the control device is configured to perform the following processing: (a) a process of positioning the distance measuring device at a distance measuring position for measuring the distance to a workpiece by setting the movable stage at a first position; (b) a process of performing distance measurement by the distance measuring device and performing teaching using the result of the distance measurement while the movable stage is set at the first position; (c) a process of positioning the end effector at a work position for performing a robotic operation on the workpiece by setting the movable stage at a second position different from the first position; and (d) a process of performing the robotic operation on the workpiece in a state where the movable stage is set at the second position.

Images