Robotic system, method and computer program for performing scraping and grinding

Abstract

Conventionally, the operation of forming a plurality of concave and convex portions arranged in one direction on the surface of a workpiece by scraping is performed manually by a skilled person. A robot system (10) comprises: a robot (12) that moves a scraping tool (16) for scraping the surface of a workpiece; and a control device (18) that controls the robot (12). The control device (18) performs the scraping process by pressing the scraping tool (16) against the surface while moving the scraping tool in a direction along the surface. During the execution of the scraping process, the control device controls the position of the robot (12) in such a manner that the pressure with which the robot (12) presses the scraping tool (16) against the surface is repeatedly increased and decreased, thereby repeatedly increasing and decreasing the depth of the surface scraped.

Description

Technical Field

[0001] The present disclosure relates to a robot system, method, and computer program for performing a scraping process. Background Art

[0002] A robot that performs scraping processing is known (for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2004-042164 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] Conventionally, the operation of forming a plurality of concave and convex portions aligned in one direction on the surface of a workpiece by scraping has been performed manually by skilled workers.

[0008] Solutions for solving problems

[0009] In one embodiment of the present disclosure, a robot system is provided for performing a scraping process for scraping the surface of a workpiece to make it flat. The robot system comprises: a robot for moving a scraping tool for scraping the surface; and a control device for controlling the robot, wherein the control device performs the scraping process by using the robot to press the scraping tool against the surface while moving the scraping tool in a direction along the surface. During the scraping process, the control device repeatedly increases and decreases the depth of the surface scraping by controlling the position of the robot in such a manner as to repeatedly increase and decrease the pressing force of the scraping tool against the surface.

[0010] In another embodiment of the present disclosure, a method is a scraping process for scraping the surface of a workpiece to make it flat using a robot, wherein the robot moves a scraping tool used for scraping the surface, and the method includes the following steps: performing the scraping process by using the robot to press the scraping tool against the surface while moving the scraping tool in a direction along the surface; and during the execution of the scraping process, repeatedly increasing and decreasing the depth of the surface scraping by controlling the position of the robot in a manner that repeatedly increases and decreases the pressing force of the scraping tool pressed against the surface by the robot.

[0011] Effects of the Invention

[0012] According to the present disclosure, a concave portion having multiple valleys and peaks arranged in one direction can be quickly formed by the robot's motion. This reduces the scraping cycle time and enables the automatic formation of concave portions of the same quality as those formed by skilled workers. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic diagram of a robot system according to one embodiment.

[0014] Figure 2 yes Figure 1 Block diagram of the robotic system shown.

[0015] Figure 3 It is from Figure 1 Observe the arrow B in Figure 1 An enlarged view of the scraper is shown.

[0016] Figure 4 Show that Figure 1 The scraping tool is shown pressed against the surface of the workpiece.

[0017] Figure 5 An example of teaching points set on the surface of a workpiece is shown.

[0018] Figure 6 This is a diagram for explaining a speed command as a position control command and a speed command as a force control command.

[0019] Figure 7 The actual movement trajectory of the scraping tool during the scraping process is shown.

[0020] Figure 8 The following shows the temporal variation characteristics of the pressing force in force control according to one embodiment.

[0021] Figure 9 The recessed portion formed by the scraping process is schematically shown.

[0022] Figure 10 The recessed portion formed by the scraping process is schematically shown.

[0023] Figure 11 The state of the shank of the scraping tool during the scraping process is schematically shown.

[0024] Figure 12 The following shows the temporal variation characteristics of the pressing force in force control according to another embodiment.

[0025] Figure 13 The following shows the temporal variation characteristics of the pressing force in force control according to still another embodiment.

[0026] Figure 14 The following shows the temporal variation characteristics of the pressing force in force control according to still another embodiment.

[0027] Figure 15 The following shows the temporal variation characteristics of the pressing force in force control according to still another embodiment.

[0028] Figure 16 An example of the operation flow of the scraping method is shown.

[0029] Figure 17 Show Figure 16 An example of the process of step S1 in .

[0030] Figure 18 Show Figure 16 An example of the process of step S2 in .

[0031] Figure 19 Shown in Figure 17 The time variation characteristics of the pressing force in the force control performed in step S13 in FIG.

[0032] Figure 20 Another example of the trajectory of the scraping tool during the scraping process is shown.

[0033] Figure 21 Another example of teaching points set on the surface of a workpiece is shown. DETAILED DESCRIPTION

[0034] The following describes the embodiments of the present disclosure in detail based on the accompanying drawings. In the various embodiments described below, identical elements are denoted by the same reference numerals, and duplicate descriptions are omitted. In the following description, the positive x-axis direction of the robot coordinate system C1 in the drawings is sometimes referred to as the right, the positive y-axis direction as the front, and the positive z-axis direction as the top.

[0035] First, refer to Figure 1 and Figure 2 The following describes a robot system 10 according to one embodiment. The robot system 10 performs a scraping process for flattening the surface Q of a workpiece W. Scraping is a process in which the surface Q of the workpiece W is scraped to form microscopic irregularities within a predetermined range (e.g., μm order) in the thickness direction of the workpiece W. These microscopic irregularities function as so-called "oil reservoirs" for accumulating lubricating oil on the surface Q, which serves as a sliding surface.

[0036] The robot system 10 includes a robot 12, a force sensor 14, a scraping tool 16, and a control device 18. In this embodiment, the robot 12 is a vertical multi-jointed robot having a robot base 20, a rotating body 22, a lower arm 24, an upper arm 26, and a wrist 28. The robot base 20 is fixed to the floor of a work cell. The rotating body 22 is mounted on the robot base 20 so as to be rotatable about a vertical axis.

[0037] The lower arm 24 is rotatably mounted on the rotating body 22 about a horizontal axis, and the upper arm 26 is rotatably mounted on the front end of the lower arm 24. The wrist 28 includes a wrist base 28a rotatably mounted on the front end of the upper arm 26 and a wrist flange 28b rotatably mounted on the wrist base 28a about the wrist axis A1.

[0038] A servo motor 34 is provided in each component of the robot 12 (the robot base 20, the rotating body 22, the lower arm 24, the upper arm 26, and the wrist 28). Figure 2 These servo motors 34 rotate the various movable elements of the robot 12 (the rotating body 22, the lower arm 24, the upper arm 26, the wrist 28, and the wrist flange 28b) about the drive axis in response to commands from the control device 18. As a result, the robot 12 can move the scraping tool 16 and arrange it in any position and posture.

[0039] The force sensor 14 is used to detect the pressing force F applied by the robot 12 to the surface Q of the workpiece W by pressing the scraping tool 16. For example, the force sensor 14 is a six-axis force sensor having a cylindrical main body and a plurality of strain gauges provided on the main body. The force sensor 14 is inserted between the wrist flange 28b and the scraping tool 16. In this embodiment, the force sensor 14 is arranged so that its central axis coincides with the wrist axis A1.

[0040] The scraping tool 16 is fixed to the front end of the force sensor 14 and is used to scrape the surface of the workpiece W for grinding. Specifically, the scraping tool 16 includes a flexible handle 30 and a blade 32 fixed to the front end of the handle 30. The base end of the handle 30 is fixed to the front end of the force sensor 14, and the handle 30 is connected to the wrist flange 28b of the robot 12 via the force sensor 14.

[0041] The handle 30 extends linearly from the distal end of the force sensor 14 along the axis A2. The blade 32 is made of a metal material (e.g., steel) having a higher rigidity than the handle 30. The blade 32 extends from its base end 32b to its distal end 32a along the axis A2. Alternatively, the axis A2 may be substantially perpendicular to the wrist axis A1.

[0042] like Figure 3 As shown, from the upper side ( Figure 1 The front end 32a of the blade 32 is curved so as to bulge outward from both ends in the width direction toward the center. The scraping tool 16 pushes the front end 32a of the blade 32 against the surface Q of the workpiece W and scrapes the surface Q with the front end 32a.

[0043] The control device 18 controls the movement of the robot 12. Figure 2 As shown, the control device 18 is a computer including a processor 40, a memory 42, an I / O interface 44, an input device 46, and a display device 48. The processor 40 is communicatively connected to the memory 42, the I / O interface 44, the input device 46, and the display device 48 via a bus 50. The processor 40 performs computational processing for executing the scraping process while communicating with these components.

[0044] The memory 42 includes RAM, ROM, or the like, and is used to temporarily or permanently store various data used in the computations executed by the processor 40, as well as various data generated during the computations. The I / O interface 44 includes, for example, an Ethernet (registered trademark) port, a USB port, an optical fiber connector, or an HDMI (registered trademark) terminal, and communicates data with external devices via wired or wireless connections in response to instructions from the processor 40. In this embodiment, the force sensor 14 and each servo motor 34 of the robot 12 are communicatively connected to the I / O interface 44.

[0045] The input device 46 includes a keyboard, a mouse, a touch panel, or the like, and allows the operator to input data. The display device 48 includes a liquid crystal display or an organic EL display, and displays various data in a visually recognizable manner under instructions from the processor 40. The input device 46 and the display device 48 may be integrally assembled with the housing of the control device 18, or may be separately mounted externally thereto.

[0046] like Figure 1 As shown, a robot coordinate system C1 is set for the robot 12. The robot coordinate system C1 is a coordinate system used to control the motion of each movable element of the robot 12. The robot coordinate system C1 is fixed relative to the robot base 20. In this embodiment, the robot coordinate system C1 is set for the robot 12 so that its origin is located at the center of the robot base 20 and its z-axis coincides with the rotation axis of the rotating body 22.

[0047] On the other hand, a tool coordinate system C2 is set for the scraping tool 16. The tool coordinate system C2 is a coordinate system used to define the position and posture of the scraping tool 16 (or the wrist flange 28b) in the robot coordinate system C1. In this embodiment, the tool coordinate system C2 is set for the scraping tool 16 so that its origin (the so-called TCP) is located at the center of the tip 32a of the blade 32 when the shank 30 is not bent, and its z-axis is parallel to the axis A2 (or the normal direction of the curved surface of the tip 32a at the center of the tip 32a).

[0048] When moving the scraping tool 16, the processor 40 of the control device 18 sets the tool coordinate system C2 in the robot coordinate system C1 and generates commands (position commands, speed commands, torque commands, etc.) for each servo motor 34 of the robot 12 so that the scraping tool 16 is arranged at the position and posture represented by the set tool coordinate system C2. In this way, the processor 40 positions the scraping tool 16 at a desired position and posture in the robot coordinate system C1, thereby performing the scraping process.

[0049] On the other hand, a sensor coordinate system C3 is set for the force sensor 14. The sensor coordinate system C3 is a coordinate system for defining the direction of the force acting on the force sensor 14. In this embodiment, the sensor coordinate system C3 is set for the force sensor 14 so that its origin is located at the center of the force sensor 14 and its z-axis is aligned with the wrist axis A1 (or its x-axis is parallel to the z-axis of the tool coordinate system C2).

[0050] exist Figure 4 3 shows a state in which the robot 12 is pressing the tip 32 a of the blade 32 of the scraping tool 16 against the surface Q of the workpiece W. When the robot 12 presses the tip 32 a of the scraping tool 16 toward the surface Q in a direction perpendicular to the surface Q with a pressing force F, a reaction force F′ to the pressing force F is applied from the surface Q via the scraping tool 16 to the force sensor 14.

[0051] Each strain gauge of the force sensor 14 transmits detection data corresponding to the force acting on the force sensor 14 at that time to the control device 18. Based on the detection data received from the force sensor 14 via the I / O interface 44, the processor 40 determines the force f acting on the force sensor 14 at that time in the x-, y-, and z-axis directions of the sensor coordinate system C3, as well as the torque τ about the x-, y-, and z-axes. Based on the force f and torque τ, as well as the current state data CD of the scraping tool 16, the processor 40 calculates the magnitude of the reaction force F' acting on the tip 32a of the blade 32 in a direction perpendicular to the surface Q.

[0052] State data CD includes, for example, at least one of the angle θ1 between axis A2 and surface Q, the distance d from wrist axis A1 (or the origin of sensor coordinate system C3) to tip 32a of blade 32, position data indicating the position and posture of tool coordinate system C2 (or sensor coordinate system C3) in robot coordinate system C1, and bending data of handle 30 (e.g., the bending amount or elastic modulus of handle 30). Thus, force sensor 14 detects reaction force F' as pressing force F, and control device 18 can determine the magnitude of pressing force F (reaction force F') based on the detection data of force sensor 14.

[0053] Next, refer to Figures 5 to 7 The scraping process performed by the robot 12 is described below. Figure 5 As shown, multiple teaching points TP1, TP2 and TP3 are set along the surface Q of the workpiece W located at a known position in the robot coordinate system C1, and the multiple teaching points TP1, TP2 and TP3 should position the front end 32a (that is, TCP) of the scraping tool 16 to perform scraping processing.

[0054] In this embodiment, the teaching point TP2 is set to a position away from the teaching point TP1 to the right, and the teaching point TP3 is set to a position away from the teaching point TP2 to the upper right. In addition, the positions of the teaching points TP1 and TP2 in the z-axis direction of the robot coordinate system C1 are substantially the same. n (n=1, 2, 3) are expressed as coordinates of the robot coordinate system C1.

[0055] When performing scraping, the processor 40 starts position control α to generate a position control for moving the scraping tool 16 to the teaching point TP by the robot 12. n Position control command PC n The processor 40 follows the position control instruction PC n By operating the servo motors 34 of the robot 12, the scraping tool 16 is positioned in the order of the teaching points TP1 → TP2 → TP3. By this position control α, the processor 40 moves the scraping tool 16 (specifically, the tip 32a) along the plurality of teaching points TP1 → TP2 → TP3. n The MP moves along a predetermined movement path.

[0056] In addition, in this embodiment, for ease of understanding, it is assumed that the surface Q of the workpiece W is substantially parallel to the xy plane of the robot coordinate system C1, and the direction MD of the movement path MP is substantially parallel to the xz plane of the robot coordinate system C1. n The scraping tool 16 (ie, the wrist flange 28b of the robot 12) is moved to the teaching point TP. n Speed V P_nCarry out the specified speed instruction PC V_n .

[0057] After the position control α is started, the processor 40 moves the robot 12 according to the position control instruction PC1 to move the scraping tool 16 to the teaching point TP1. Figure 6 As shown, the front end 32a is separated from the surface Q upward.

[0058] When the scraping tool 16 reaches the teaching point TP1, the processor 40 starts the force control β. After the force control β starts, the processor 40 controls the pressing force F to a predetermined target value based on the detection data of the force sensor 14. The position of the wrist flange 28b (or TCP) of the robot 12 is controlled in a manner, and the pressing force F is the force with which the robot 12 presses the scraping tool 16 against the surface Q of the workpiece W.

[0059] Specifically, the processor 40 generates a force control signal for controlling the position of the wrist flange 28b (TCP) of the robot 12 in the force control β so as to control the pressing force F (specifically, the reaction force F') obtained based on the detection data of the force sensor 14 to a target value. Then, the processor 40 adds the force control instruction FC to the position control instruction PC. n , to operate the servo motor 34 of the robot 12.

[0060] Thus, the processor 40 follows the position control instruction PC n The scraping tool 16 (or wrist flange 28b) is moved along the surface Q in the direction MD of the moving path MP, and the scraping tool 16 is moved in the direction of approaching or separating from the surface Q of the workpiece W (i.e., the z-axis direction of the robot coordinate system C1) according to the force control instruction FC.

[0061] The force control command FC has: force command FC F , which is used to specify the target value And speed command FC V , which is used to specify the speed at which the scraping tool 16 moves in the z-axis direction of the robot coordinate system C1 so that the pressing force F reaches the target value In force control β, the processor 40 first generates a force command FC F , then, based on the force instruction FC F The speed command FC is generated based on the pressing force F obtained from the detection data of the force sensor 14. V Then, the processor 40 follows the speed instruction FC VBy operating the robot 12 , the scraping tool 16 (wrist flange 28 b ) is moved in the z-axis direction of the robot coordinate system C1 .

[0062] When the scraping tool 16 reaches the teaching point TP1, the processor 40 generates a speed instruction PC V_2 As the position control command PC2 for moving the scraping tool 16 to the teaching point TP2, the speed command FC is generated. V_0 As force control instruction FC. Figure 6 FIG. 2 schematically shows the speed instruction PC generated by the processor 40 when the scraping tool 16 reaches the teaching point TP1. V_2 and speed command FC V_0 .

[0063] After the scraping tool 16 reaches the teaching point TP1, the processor 40 follows the speed instruction PC V_2 The robot 12 is operated to move the scraping tool 16 toward the teaching point TP2 in accordance with the speed instruction PC. V_2 The corresponding (specifically, consistent) speed V P_2 Move along surface Q in direction MD.

[0064] At the same time, the processor 40 generates a speed command FC V_0 To control the pressing force F to the target value And the speed instruction FC V_0 Added to the speed command PC for the servo motor 34 V_2 In this way, the scraping tool 16 is moved in the direction toward the surface Q (ie, downward) at a speed corresponding to the speed instruction FC. V_0 The corresponding (specifically, consistent) speed V F_0 As a result, the robot 12 moves the scraping tool 16 after passing the teaching point TP1. Figure 6 Move in the direction MD'.

[0065] exist Figure 7 The solid line in FIG. 2 shows the actual trajectory TR of the scraping tool 16 (specifically, the tip 32a) during the scraping process. After passing the taught point TP1, the scraping tool 16 moves toward the surface Q along the trajectory TR, which is inclined at an angle θ2 (<90°) relative to the surface Q, and contacts the surface Q at position P1.

[0066] Here, when Figure 7 When the distances between the teaching point TP1 and the position P1 in the x-axis and z-axis directions of the robot coordinate system C1 are set to x1 and z1 respectively, the distances x1 and z1, the speed command PC V_2 (Speed V P_2 ) and speed command FC V_0(Speed V F_0 ) satisfies the following formula (1).

[0067] z1 / x1=FC V_0 / PC V_2 =V F_0 / V P_2 …(1)

[0068] In addition, angle θ2, distance x1 and z1, speed command PC V_2 (Speed V P_2 ) and speed command FC V_0 (Speed V F_0 ) satisfies the following formula (2).

[0069] θ2=tan -1 (z1 / x1)=tan -1 (FC V_0 / PC V_2 )=tan -1 (V F_0 / V P_2 )…(2)

[0070] Therefore, if the machining conditions MC for scraping are set to x1 = 10 [mm] and z1 = 5 [mm], the angle θ2 can be determined to be 26.6° according to equation (2). P_2 (i.e. speed command PC V_2 ) is set to 100 [mm / sec], the speed V can be calculated according to formula (1): F_0 (i.e. speed command FC V_0 ) is determined to be 50 [mm / sec]. As such, the distances x1 and z1, and the speed command PC are appropriately set as the machining conditions MC. V_2 (Speed V P_2 ) and speed command FC V_0 (Speed V F_0 ), thereby enabling the angle θ2 to be controlled within a desired range (e.g., 15° to 35°).

[0071] While the scraping tool 16 is in contact with the surface Q, the processor 40 moves the scraping tool 16 in the direction MD (ie, rightward) according to the position control command PC2 and generates a speed command FC. V_1 As a method for controlling the pressing force F to a target value by force control β The force control command FC. According to the speed command FC V_1 The position of the wrist flange 28b of the robot 12 is adjusted to the same value as the speed command FC in the z-axis direction of the robot coordinate system C1. V_1The corresponding (specifically, consistent) speed V F_1 Perform displacement.

[0072] Here, the speed command FC generated while the scraping tool 16 is in contact with the surface Q is V_1 (i.e. speed V F_1 ) can be set to a maximum value greater than the speed command FC generated before the scraping tool 16 contacts the surface Q. V_0 (i.e. speed V F_0 ) is large. Thus, the processor 40 uses the robot 12 to move the scraping tool 16 to the target value. The scraping process is performed by scraping the surface Q with the tip 32 a of the scraping tool 16 while pressing with a corresponding pressing force F and moving rightward along the surface Q.

[0073] When the scraping tool 16 (or the wrist flange 28b) reaches the position corresponding to the taught point TP2, the processor 40 terminates force control β and generates a position control command PC3 for moving the scraping tool 16 toward the taught point TP3. The processor 40 then operates the robot 12 in accordance with the position control command PC3, thereby moving the scraping tool 16 upward and rightward toward the taught point TP3.

[0074] As a result, the scraping tool 16 moves upward and rightward along a trajectory TR inclined at an angle θ3 (<90°) relative to the surface Q of the workpiece W, and the tip 32a of the scraping tool 16 separates from the surface Q at position P2. In this way, the scraping tool 16 scrapes the surface Q from position P1 to position P2 over the entire distance x2, completing the scraping process. In this embodiment, the coordinates of position P2 in the x-axis direction of the robot coordinate system C1 are assumed to be approximately the same as the taught point TP2. Subsequently, the scraping tool 16 reaches the taught point TP3 (or a position directly below it).

[0075] In this embodiment, the processor 40 controls the position of the wrist flange 28b of the robot 12 so as to repeatedly increase and decrease the pressing force F during the scraping process from position P1 to position P2, thereby repeatedly increasing and decreasing the depth Z of the scraped surface Q. Figure 8 , to illustrate this function.

[0076] Figure 8 An example of the time variation characteristics of the pressing force F during the scraping process is shown. Figure 8In the example shown, the pressing force F is varied in such a manner that the pressing force F is repeatedly increased and decreased between a first force F1 and a second force F2 (>0) during the scraping process, and the second force F2 is smaller than the first force F1. In this embodiment, the processor 40 controls the pressing force F as follows by performing force control β during the scraping process. Figure 8 Increase or decrease as shown.

[0077] As an example of force control β, the processor 40 generates a force command FC as the force control command FC as follows: F That is, the processor 40 generates an initial target value for specifying the pressing force F after the force control β starts. Force command FC F , and follow the force instruction FC F The robot 12 is moved. Figure 7 As shown, at position P1 , the pressing force F contacts the surface Q and starts to increase, reaching a second force F2 at time t1 .

[0078] Next, the processor 40 generates a force command FC F , the force instruction FC F This function is used to increase the pressing force F by a change amount ΔF within a predetermined time τ1 starting at time t1, and then decrease the change amount ΔF within a predetermined time τ2. Furthermore, the time τ1 and the time τ2 can be set to the same time (τ1 = τ2) or different times (τ1 < τ2 or τ1 > τ2).

[0079] Thus, the pressing force F increases to the first force F1 (= F2 + ΔF) at time t2 = t1 + τ1 after a time τ1 has passed from time t1, and then decreases to the second force F2 at time t3 = t2 + τ2. Figure 8 The waveform of the first peak FP1 in the time variation characteristics of the pressing force F shown is formed during the period from the time point t1 to the time point t3 .

[0080] Thereafter, the processor 40 generates a force command FC so that the pressing force F repeats the following cycle: F : After increasing the change amount ΔF in time τ1, the change amount ΔF is reduced in time τ2. By following the force command FC generated in this way F The position of the wrist flange 28b of the robot 12 is controlled so that the pressing force F is periodically changed as shown in FIG. Figure 8 As shown in FIG. 1 , a peak FP of the pressing force F is formed at a period T (=τ1+τ2). n (n=1, 2, 3...) waveforms.

[0081] Therefore, in this case, the processor 40 sets the target value of the pressing force F to At the first target value and the second target value The first target value changes between The second target value is the value obtained by increasing the pressing force F at the time point t1 by the change amount ΔF. The value obtained by reducing the pressing force F at the time point t2 by the change amount ΔF. The force may be set to F1 or F2, or may be set to any force value.

[0082] As another example of force control β, the processor 40 may generate a force command FC as the force control command FC as follows: F That is, after the force control β is started, the processor 40 generates a first target value for specifying the first force F1. Force command FC F By following the force instruction FC F The robot 12 is operated so that the scraping tool 16 contacts the surface Q at the position P1 , and the pressing force F reaches the second force F2 at the time point t1 , and then reaches the first force F1 at the time point t2 .

[0083] Then, the processor 40 generates a second target value for specifying the second force F2 at the time point t2. Force command FC F By following the force instruction FC F The robot 12 is moved so that the pressing force F decreases from time t2 and reaches the second force F2 at time t3. At this time t3, the processor 40 again generates the force command FC F Specify the first target value

[0084] Afterwards, the processor 40 generates the force command FC F Repeat the following cycle: specify the second target value after time τ1 And specify the first target value after time τ2 In this way, the processor 40 sets the target value of the pressing force F to At the first target value and the second target value The second target value changes periodically between than the first target value As a result, it is possible to Figure 8 The pressing force F is varied in a cycle T as shown.

[0085] In addition, the first target value used in this example Can be the same value as the first force F1 Alternatively, it may be a value greater than the first force F1 exist In the case of the pressing force F not reaching the first target value at time t2 When the pressing force F reaches the first target value, the processor 40 Previously generated to specify the second target value Force command FC F .

[0086] In addition, the second target value Can be the same value as the second force F2 Alternatively, it may be a value smaller than the second force F2 exist In the case of the pressing force F not reaching the second target value at time t3 When the pressing force F reaches the second target value, the processor 40 Previously generated to specify the first target value Force command FC F .

[0087] As another example of force control β, the processor 40 may also set the target value of the pressing force F to Press and Figure 8 The force command FC is generated in such a manner that the time-varying characteristic corresponding to the characteristic shown changes with time. F For example, the processor 40 sets the target value The force command FC is generated so as to change step by step with time at a predetermined control period T' (<<T). F . Thus, the target value can be To become Figure 8 The characteristics shown correspond to the time-varying characteristics in the manner of the first target value and the second target value Changes periodically.

[0088] As described above, in this embodiment, the processor 40 sets the target value of the pressing force F in the force control β. Repeatedly increase and decrease to increase or decrease the pressing force F. Figure 9 , an example of a concave portion R formed on the surface Q by the scraping method according to the present embodiment is shown. According to the present embodiment, the pressing force F is periodically increased and decreased during the execution of the scraping process (in other words, during the period when the scraping tool 16 is pressed against the surface Q and moved in the direction MD), thereby Figure 9 As shown, the depth Z of the scraped surface Q is periodically increased and decreased.

[0089] More specifically, the recess R extends rightward from the position P1 to the position P2, and a plurality of valleys E are formed in the recess R so as to be aligned along the x-axis direction of the robot coordinate system C1. n (n=1, 2, 3...) and multiple mountain parts G n . Tanibe E n exist Figure 8 The characteristics shown correspond to the first force F1 (first target value) of the pressing force F. ) is the portion where the depth Z in the recess R is the largest.

[0090] On the other hand, Yamabe G n exist Figure 8 The characteristics shown correspond to the pressing force F as the second force F2 (the second target value ) is the part with the smallest depth Z. In this embodiment, the second force F2 is greater than zero, so the mountain G n Depth Z (i.e., the distance between the surface Q in the z-axis direction of the robot coordinate system C1 and the mountain G n The distance between them) is greater than 0 (that is, the mountain G n Located below the surface Q). In addition, Figure 9 In the figure, the depth Z of the recess R is shown in an exaggerated manner for ease of understanding, but it is actually desired to understand that the depth Z is on the order of μm.

[0091] According to this embodiment, the recess R extending from the position P1 to the position P2 and having a plurality of valleys E therein can be formed by a single scraping process. n and Yamabe G n Here, in the past, a skilled person in scraping and grinding formed a Figure 9 As shown, a plurality of valleys E arranged in one direction n In order to form a valley E n , it is necessary to repeatedly push the scraping tool against the surface Q with a strong force to scrape the surface Q, and then separate the scraping tool from the surface Q. Such work imposes heavy physical labor on a skilled worker and requires a lot of time.

[0092] According to this embodiment, the robot 12 can quickly form a surface Q that is repeatedly scraped by a skilled person using a scraping tool. Figure 9 As shown in FIG, the concave portion R. Therefore, the cycle time of the scraping process can be reduced, and the concave portion R having the same quality as the concave portion formed by a skilled person can be automatically formed.

[0093] In the present embodiment, the processor 40 executes the force control β during the scraping process, and sets the target value to The pressing force F is increased and decreased by repeating the increase and decrease. Specifically, the processor 40 makes the target value At the first target value and the second target value According to this structure, the pressing force F can be controlled with high precision to change as follows Figure 8 The characteristics shown change with time. Therefore, the depth Z of the recess R can be managed with high precision.

[0094] In addition, in this embodiment, the processor 40 performs position control α and force control β together, so that the scraping tool 16 moves in the direction MD while pressing on the surface Q. According to this structure, the trajectory TR of the scraping tool 16 can be controlled with high precision. In addition, in this embodiment, the processor 40 increases and decreases the pressing force F periodically (specifically, according to the period T). According to this structure, the valley E can be formed. n The recessed portions R are arranged at equal intervals in the x-axis direction of the robot coordinate system C1.

[0095] In addition, the first target value mentioned above It may also be determined as a value that allows the shank 30 to bend when the blade 32 is pressed against the surface Q with the first force F1 during the scraping process. Figure 11 FIG schematically shows a state where the handle 30 is bent during the scraping process. Figure 11 In the example shown, the robot 12 presses the front end 32a of the scraper 16 against the surface Q with the first force F1, thereby causing the handle 30 of the scraper 16 to bend downward. Alternatively, the second target value may be determined so that the handle 30 of the scraper 16 also bends when the scraper 16 is pressed against the surface Q by the second force F2.

[0096] In addition, the memory 42 may also store in advance the target value as described above. In this case, the processor 40 determines the target value according to the target value setting program PG1 after the force control β starts. And generate the value for specifying the target Force command FC F .

[0097] In addition, as the pressing force F (target value) in the scraping process ) The method of increase or decrease is not limited to Figure 8 The following example refers to Figures 12 to 15 To explain the pressing force F (target value )Other ways to increase or decrease. Figure 12In the example shown, the processor 40 causes the pressing force F to vary between a first force F1 and a second force F2 (<F1) in a cycle T.

[0098] Here, Figure 12 the second force F2 shown is set to be higher than Figure 8 the second force F2 shown. According to Figure 12 the example shown, it is possible to make the depth F of the peak portion G of the concave portion R formed relatively large. The processor 40 can control the pressing force F to have the time-varying characteristics as shown n by the same method as the force control β described with reference to Figure 8 . Figure 12

[0099] During Figure 13 the scraping process in the example shown, the pressing force F varies in a manner of repeatedly increasing and decreasing between the first force F1 and the second force F2. However, the pressing force F is maintained as the first force F1 throughout the entire range of a specified time τ3. As shown Figure 13 , as an example of the force control β for increasing and decreasing the pressing force F, after the start of the force control β, the processor 40 generates a force command FC for specifying an initial target value F in the same manner as in the above-described embodiment, and causes the robot 12 to operate in accordance with this force command FC F . As a result, the pressing force F reaches the second force F2 at the time point t1.

[0100] Next, the processor 40 generates a force command FC F for causing the pressing force F to increase by a change amount ΔF within a time τ1 from the time point t1 and to be maintained throughout the entire range of a specified time τ3, and then to decrease by the change amount ΔF within a time τ2. As a result, the pressing force F increases to the first force F1 at the time point t2 = t1 + τ1 from the time point t1, is maintained as the first force F1 from the time point t2 to the time point t3 = t2 + τ3, and then decreases to the second force F2 at the time point t4 = t3 + τ2 from the time point t3. Thus, F the waveform of the first peak FP1 in the time-varying characteristics of the pressing force F shown Figure 13 is formed during the period from the time point t1 to the time point t4.

[0101] After that, the processor 40 generates a force command FC F in such a way that the pressing force F repeats the following cycle: increasing by the change amount ΔF within a time τ1 and being maintained throughout the entire range of a time τ3, and then decreasing by the change amount ΔF within a time τ2. By operating in accordance with the force command FC F ​The position of the robot 12 is controlled so that the pressing force F changes periodically between the first force F1 and the second force F2. Figure 13 As shown, the peak FP of the pressing force F is formed at a period T (=τ1+τ2+τ3) n (n=1, 2, 3...) waveforms.

[0102] As another example of force control β, the processor 40 generates a force command FC after the force control β is started. F The first target value corresponding to the first force F1 is specified in And follow the force instruction FC F The robot 12 is operated. As a result, the pressing force F reaches the second force F2 at time t1 and then reaches the first force F1 at time t2.

[0103] Afterwards, the processor 40 generates the force command FC F The first target value is continuously specified from time point t2 to time point t3 And specify the second target value at time point t3 By following such force instruction FC F The robot 12 is operated so that the pressing force F is maintained at the first force F1 from time t2 to time t3 , and then decreases from time t3 to reach the second force F2 at time t4 .

[0104] At this time point t4, the processor 40 again generates the force command FC F Specify the first target value in Afterwards, the processor 40 generates the force command FC F Repeat the following cycle: specify the second target value after time τ1+τ3 And specify the first target value after time τ2 As a result, it can be Figure 13 As shown, the pressing force F is changed at a period T between the first force F1 and the second force F2.

[0105] As another example of force control β, the processor 40 may also set the force command FC F Target value of the pressing force F With Figure 13 The time variation characteristics shown in the figure are changed in stages according to the control period T' (<<T). Figure 13 The force control β shown can form a valley E extending linearly parallel to the x-axis of the robot coordinate system C1. n The concave part R.

[0106] exist Figure 14In the example shown, the processor 40 changes the peak value of the first force F1 at each cycle T. Specifically, the processor 40 changes the peak value of the first force F1 at each cycle T. Figure 14 The 2m-1th (m is a positive integer) peak FP 2m-1 In the waveform of the pressing force F, the pressing force F is maintained at force F1. _A On the other hand, at the 2mth peak FP 2m In the waveform of the pressing force F, the pressing force F is maintained at force F1. _B ( <F1 _A ).

[0107] Figure 14 The force control β method shown is similar to Figure 13 The difference is as follows. That is, the processor 40 makes the force command FC F Specified first target value According to each cycle T and force F1 _A Corresponding target value Tongyuli F1 _B Corresponding target value Switch between them.

[0108] exist Figure 14 In the example shown, a first valley E extending linearly can be formed. n_A and the depth is greater than that of the first valley E n_A The second valley E is shallow and extends linearly. n_B In addition, the processor 40 may also be Figure 14 The 2m-1 peak FP in 2m-1 In the waveform of the pressing force F, the pressing force F is maintained at force F1 _B On the other hand, at the 2m peak FP 2m In the waveform of the pressing force F, the pressing force F is maintained at force F1 _A Generate force command FC F .

[0109] exist Figure 15 In the example shown, Figure 13 Likewise, the processor 40 maintains the pressing force F at the first force F1 throughout the entire range of the predetermined time. Figure 15 The second force F2 shown is set to be greater than Figure 13 The second force F2 is shown to be high. Figure 15 In the example shown, the peak G of the recess R can be formed n The depth F is relatively large. The processor 40 performs the reference Figure 13 The force control β is explained, so that the pressing force F can be controlled to Figure 15 The time variation characteristics are shown.

[0110] In addition, the processor 40 may also automatically determine at least one of the processing conditions MC based on the input data from the operator. For example, the processing conditions MC may include Figure 7 The angle θ2, distance x1 and z1, and speed command PC shown V_2 (Speed V P_2 ) and speed command FC V_0 (Speed V F_0 ) In addition, it also includes the length x2 of the recess R formed, the valley E formed in the recess R n (or Yamabe G n ) number k and depth Z( Figure 9 ), two adjacent hills G in the x-axis direction of the robot coordinate system C1 n and G n+1 (or two valleys E n and E n+1 ) distance X( Figure 9 ), the cycle T of changing the pressing force F, the target value of force control β and at least one of a gain Ga for determining the responsiveness of the control of the robot 12 .

[0111] As an example, the operator operates the input device 46 to input the speed command PC V_2 (Speed V P_2 ), the length x2, number k, and depth Z of the recesses R are used as processing conditions MC. In this case, the processor 40 automatically determines the distance X as X=x2 / k (or its approximate value) based on the input length x2 and number k.

[0112] In addition, the processor 40 automatically determines the target value according to the input depth Z. For example, the memory 42 may also store in advance the first target value With Yabe E n Depth Z (or the second target value With Yamabe G n In this case, the processor 40 can retrieve the target value corresponding to the input depth Z from the data table DT1. (or ), to automatically determine the target value

[0113] In addition, the processor 40 calculates the speed based on the distance X (=x2 / k) determined as described above and the input speed command PC. V_2 (Speed V P_2 ) to automatically determine the period T as T = X / PC V_2 (=X / V P_2Here, whether the robot 12 can change the pressing force F at the determined period T (in other words, move the wrist flange 28b up and down at the period T) depends on the gain Ga. Specifically, the higher the gain Ga, the faster the control responsiveness of the robot 12, and the faster the robot 12 can move the wrist flange 28b up and down.

[0114] The processor 40 may automatically determine the gain Ga that enables the robot 12 to operate at the period T when the period T is determined. In this case, if the gain Ga that can achieve the determined period T cannot be set (for example, if the gain Ga is outside the range of settable gain Ga), the processor 40 may issue a warning signal to inform of this fact.

[0115] As another example, the operator may input the gain Ga as the machining condition MC instead of the speed command PC. V_2 (Speed V P_2 In this case, the processor 40 may automatically determine the period T based on the input gain Ga. For example, the memory 42 may store in advance a data table DT2 in which the gain Ga and the period T are stored in association with each other.

[0116] In this case, the processor 40 can automatically determine the period T by searching the data table DT2 for the period T corresponding to the input gain Ga. In addition, the data table DT2 may also store the minimum period T that can be achieved with the corresponding gain Ga. MIN As the period T. By using the period T MIN To minimize the cycle time of the scraping process.

[0117] Then, the processor 40 converts the speed instruction PC into the speed instruction PC according to the cycle T and the distance X determined as described above. V_2 (Speed V P_2 ) automatically determines the PC V_2 (V P_2 )=X / T. As described above, the processor 40 can automatically determine other parameters of the machining condition MC based on a portion of the parameters of the machining condition MC input by the operator. This configuration can simplify the work required to start up the robot system 10.

[0118] Next, refer to Figures 16 to 18 The scraping method performed by the robot system 10 is described below. When the processor 40 receives a scraping start instruction from the operator, the upper controller, or the work program PG2, it starts to perform the scraping process. Figure 16In step S1, the processor 40 performs rough machining. Rough machining is, for example, scraping to reduce the microscopic irregularities formed when machining the surface Q with a milling disc or the like to a first size (eg, 10 μm) or less.

[0119] Reference Figure 17 In step S11, the processor 40 starts the position control α. Specifically, the processor 40 starts to generate the position control command PC n The robot 12 is used to move the front end 32a of the scraping tool 16 according to the teaching point TP1→TP2→TP3 ( Figure 7 ) in the order of movement.

[0120] In step S12 , the processor 40 determines whether the scraping tool 16 has reached the teaching point TP1 . For example, the servo motor 34 of the robot 12 is provided with a rotation detector (encoder, Hall element, etc.) for detecting the rotation of the servo motor 34 (specifically, the rotation angle or rotation position).

[0121] The processor 40 obtains position data of the scraping tool 16 (specifically, the TCP) in the robot coordinate system C1 based on feedback from the rotation detector and can determine whether the scraping tool 16 has reached the taught point TP1 based on this position data. If the processor 40 determines that the scraping tool 16 has reached the taught point TP1 (i.e., "Yes"), the process proceeds to step S13. If the processor 40 determines that the scraping tool 16 has not reached the taught point TP1 (i.e., "No"), the process loops back to step S12.

[0122] In step S13, the processor 40 starts the first force control β1. Specifically, the processor 40 generates a target value for specifying the first force control β1. Force command FC F The processor 40 is based on the force command FC F To generate speed command FC V_0 , and will be used as the speed command FC of the force control command FC V_0 Added to PC as position control instruction n Speed command PC V_2 As a result, the scraping tool 16 moves along the trajectory TR ( Figure 7 ) abuts against surface Q at position P1.

[0123] Here, the processor 40 maintains the pressing force F constant by the first force control β1 while performing the scraping process from the position P1 to the position P2 in step S1 (roughing). Figure 19The time variation characteristics of the pressing force F in the first force control β1 are shown in FIG. Figure 19 As shown, in the first force control β1, the processor 40 does not need to make the pressing force F as Figure 8 、 Figures 12 to 15 The pressing force F is increased or decreased as shown in the figure to maintain the pressing force F at a predetermined target value. The position of the wrist flange 28b of the robot 12 is controlled in this manner.

[0124] In step S14, the processor 40 determines whether the scraping tool 16 (or the wrist flange 28b) has reached the position corresponding to the teaching point TP2. If the determination is "yes", the processor 40 proceeds to step S15. If the determination is "no", the processor 40 loops through step S14.

[0125] In step S15, the processor 40 ends the first force control β1. After step S15, the processor 40 causes the robot 12 to move according to the position control instruction PC3, so that the scraping tool 16 moves along the direction shown in FIG. Figure 7 As shown, the trajectory TR inclined at an angle θ3 moves upward and rightward, and as a result, the scraping tool 16 separates from the surface Q1 of the workpiece W1 at position P2, and the roughing is completed. This roughing can improve the flatness of the surface Q so that the micro-concavities and convexities on the surface Q are smaller than the first size.

[0126] In step S16, the processor 40 determines whether the scraping tool 16 has reached the teaching point TP3. If the determination is "yes", the processor 40 proceeds to step S17. If the determination is "no", the processor 40 loops through step S16. Then, in step S17, the processor 40 ends the position control α.

[0127] Refer again Figure 16 In step S2, the processor 40 performs finishing. Finishing is a scraping process performed to reduce the micro-concavities and convexities formed on the rough-machined surface Q to a second size (e.g., 5 μm) smaller than the first size and to form recessed portions that function as the above-mentioned oil reservoirs.

[0128] Reference Figure 18 This step S2 will be described. Figure 18 The process shown is similar to Figure 17 Specifically, after the processor 40 determines "yes" in step S12, it starts the second force control β2 in step S13'. In the second force control β2, the processor 40 executes the above-mentioned Figure 8 、 Figures 12 to 15 The force control β described in the above is used to repeatedly increase and decrease the pressing force F.

[0129] As described above, in this embodiment, after the surface Q is scraped in step S1 (rough machining) to improve the flatness of the surface Q to a certain extent, step S2 (finishing machining) is performed, thereby further improving the flatness of the surface Q and forming a surface as shown in FIG. Figure 9 The recess R shown functions as an oil reservoir. Thus, the robot system 10 can continuously and automatically perform rough machining and finish machining.

[0130] In addition, Figure 16 In the process shown, step S2 may be executed first and then step S3. In addition, the processor 40 may also repeatedly execute steps S1 and S2 in an alternating manner. The processor 40 executes the target value setting program PG1 and the operation program PG2 according to the above-mentioned target value setting program PG1 and the operation program PG2. Figure 16 The process shown.

[0131] For example, the target value setting program PG1 is used to generate the target value The algorithm is defined in the computer program. On the other hand, the operation program PG2 is the teaching point TP. n The target value setting program PG1 and the operation program PG2 may be stored in the memory 42 as separate computer programs or may be integrated into one computer program and stored in the memory 42.

[0132] Furthermore, in the above embodiment, the processor 40 may also execute an action of swinging the scraping tool 16 (wrist flange 28b) in the y-axis direction of the robot coordinate system C1 in synchronization with the action of repeatedly increasing and decreasing the pressing force F during the execution of the scraping process. Figure 20 2 shows an example of the trajectory TR′ of the scraping tool 16 when the scraping tool 16 is swung in this manner.

[0133] For example, the processor 40 may also synchronize the increase and decrease of the pressing force F with the swing of the scraping tool 16 so that the scraping tool 16 reaches the desired position. Figure 20 When the rear swing peak point P3 and the front swing peak point P4 on the trajectory TR' shown in FIG. Figure 8 The first force F1 in the scraping tool 16 makes the pressing force F reach the middle point of the oscillation peak P3 and P4. Figure 8 According to this structure, it is possible to form a robot having valleys E arranged in a zigzag pattern in the x-axis direction of the robot coordinate system C1. n The concave part R.

[0134] In the above embodiment, the processor 40 increases and decreases the pressing force F by executing the force control β. However, the present invention is not limited thereto, and the processor 40 can also repeatedly increase and decrease the pressing force F by executing only the position control α. Figure 21 To illustrate this function.

[0135] exist Figure 21 In the method shown, the teaching point TP is set along the surface Q of the workpiece W. 11 TP 12 TP 13 TP 14 TP 15 TP 16 .... Here, the teaching point TP 12 The teaching point TP is configured at the same position in the z-axis direction as the surface Q in the robot coordinate system C1. 13 TP 14 TP 15 TP 16 ...is located below the surface Q1 in the robot coordinate system C1. In addition, the teaching point TP 13 and TP 15 Located at the teaching point TP 14 and TP 16 A position at the bottom.

[0136] exist Figure 21 In the example shown, the processor 40 executes the position control α to move the scraping tool 16 to the teaching point TP by the robot 12. 11 →TP 12 →TP 13 →TP 14 →TP 15 →TP 16 .... Thus, the scraping tool 16 moves at the teaching point TP. 12 Then, the processor 40 moves the wrist flange 28b of the robot 12 to the teaching point TP. 13 TP 14 TP 15 and TP 16 The corresponding positions are sequentially moved, and the scraping tool 16 is moved rightward along the surface Q while being pressed against the surface Q. In this way, the scraping process can be performed.

[0137] Here, by appropriately selecting Figure 21 The teaching point TP shown n (n = 11, 12, 13 ...) positions, so that the pressing force F can be controlled to Figure 8 、 Figures 12 to 15For example, appropriately set the teaching point TP n When the wrist flange 28b reaches the teaching point TP 13 and TP 15 When the pressing force F reaches the corresponding position Figure 8 The first force F1 in the wrist flange 28b reaches the teaching point TP 14 and TP 16 When the pressing force F reaches the corresponding position Figure 8 The second force F1 in.

[0138] In this case, the memory 42 may store the above-mentioned machining conditions MC and the teaching points TP in advance. n Then, the operator operates the input device 46 to input, for example, the length x2, the depth Z, the distance X, and the target value. The processor 40 can also automatically set the processing conditions MC according to the input processing conditions MC. Figure 21 The teaching point TP shown n .

[0139] In the above embodiment, the scraping process is performed once on the surface Q of the workpiece W. However, the processor 40 may also repeatedly perform the scraping process multiple times in order to form, for example, a plurality of recesses R arranged in the y-axis direction of the robot coordinate system C1. In this case, for each of the plurality of recesses R formed, a setting is made. Figure 5 or Figure 21 A set of teaching points TP is shown n .

[0140] In addition, Figure 8 、 Figures 12 to 15 In the embodiment, the first force F1 or the second force F2 may also be varied at each period T. For example, in Figure 8 In the force control β shown, the i-th peak FP i (i=1, 2, 3...) The first force F1 of the waveform i It can also be combined with the i+1th peak FP i+1 The waveform of the first force F1 i+1 different.

[0141] Similarly, the i-th peak FP i The second force F2 of the waveform i It can also be combined with the i+1th peak FP i+1 The second force F2 of the waveform i+1 In this case, the processor 40 controls the first target value of the force control β at each cycle T. (or the second target value ) with the first force F1 i (or the second force F2 i ) corresponding to the change. In addition, it is also possible to press each peak FP i The period T is changed. That is, to form the i-th peak FP i The period T i It can also be formed with the i+1th peak FP i+1 The period T i+1 Different periods.

[0142] In addition, it is also possible to Figure 8 、 Figures 12 to 15 For example, the processor 40 may also execute the force control β combination within the entire range of the prescribed period after the force control β starts. Figure 8 and Figures 12 to 15 After one force control β in Figure 8 and Figures 12 to 15 Another force in controls β.

[0143] For example, the processor 40 may also execute Figure 8 The force control β shown is then executed Figure 12 The force control β shown in the figure makes the mountain G n Alternatively, the processor 40 may also change the depth Z by executing Figure 13 The force control β shown is then executed Figure 14 or Figure 15 The force control β shown in the figure makes the valley E n and Yamabe G n The depth Z is changed. According to this structure, the recess R of various shapes can be formed.

[0144] In addition, in the above embodiment, if Figure 7 As shown, the description describes a case where the tip 32a of the scraper tool 16 reaches the taught point TP3 at the end of the scraping process, and the position P2 in the robot coordinate system C1 is substantially the same as the x-coordinate of the taught point TP2. However, in reality, it is important to understand that the tip 32a of the scraper tool 16 may deviate from the taught point TP3 (for example, downward) at the end of the scraping process, and the position P2 may deviate from the taught point TP2 (for example, in the positive x-axis direction of the robot coordinate system C1).

[0145] The force sensor 14 may be inserted between the work chamber and the robot base 20, or may be installed at any location on the robot 12. Furthermore, the force sensor 14 is not limited to being installed on the robot 12, but may also be installed on the side of the workpiece W. For example, the pressing force F can be detected by inserting the force sensor 14 between the workpiece W and the mounting surface on which the workpiece W is mounted.

[0146] The force sensor 14 is not limited to a six-axis force sensor, but may be, for example, a single-axis or three-axis force sensor, or any sensor capable of detecting the pressing force F. Furthermore, the origin of the sensor coordinate system C3 is not limited to the center of the force sensor 14, but may be located at any known position relative to the force sensor 14, and its axes may be defined in any direction.

[0147] Furthermore, the robot 12 is not limited to a vertical multi-joint robot and may be any other type of robot, such as a horizontal multi-joint robot or a parallel rod robot, or may be a mobile mechanism having multiple ball screw mechanisms. While the present disclosure has been described above using embodiments, the aforementioned embodiments do not limit the invention as defined in the claims.

[0148] Description of Reference Numerals

[0149] 10: Robot system; 12: Robot; 14: Force sensor; 16: Scraping tool; 18: Control device; 40: Processor.

Claims

1. A robot system for performing a scraping process for scraping a surface of a workpiece to make it flat, the robot system comprising: a robot that moves a scraping tool for scraping the surface; and a control device that controls the robot, in, The control device performs the scraping process by moving the scraping tool in a direction along the surface while pressing the scraping tool against the surface using the robot. During the scraping process, the control device controls the position of the robot so that the robot repeatedly increases and decreases the pressure with which the scraping tool is pressed against the surface, thereby repeatedly increasing and decreasing the depth of the scraped surface.

2. The robot system according to claim 1, wherein: A force sensor is further provided, wherein the force sensor is used to detect the pressing force. During the scraping process, the control device controls the position of the robot by executing force control to control the pressing force to a predetermined target value based on detection data of the force sensor. The control device increases and decreases the pressing force by repeatedly increasing and decreasing the target value during the force control.

3. The robot system according to claim 2, wherein: The control device changes the target value between a first target value and a second target value during the force control, wherein the second target value is smaller than the first target value.

4. The robot system according to claim 3, wherein: The scraping tool has: a flexible handle coupled to the robot; and A blade portion, fixed to the front end of the handle, for scraping the surface. The first target value is determined to be a value that can bend the handle when the blade is pressed against the surface with the pressing force corresponding to the first target value.

5. The robot system according to any one of claims 2 to 4, wherein: The control device moves the scraping tool in a direction along the surface during the scraping process by executing position control for sequentially moving the scraping tool to a plurality of predetermined teaching points along the surface together with the force control.

6. The robot system according to any one of claims 1 to 5, wherein: The control device periodically increases and decreases the pressing force.

7. A method for scraping and grinding a workpiece surface to make it flat using a robot, wherein: The robot moves a scraping tool for scraping the surface, and the method comprises the following steps: performing the scraping process by moving the scraping tool in a direction along the surface while pressing the scraping tool against the surface using the robot; and During the scraping process, the depth of the surface scraped is repeatedly increased and decreased by controlling the position of the robot so that the pressure with which the robot presses the scraping tool against the surface is repeatedly increased and decreased.

8. A computer program causing a processor to execute the method according to claim 7.

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