Apparatus, control device, robot system, method, and computer program for measuring wear amount of welding tip

Abstract

In the prior art, it was necessary to adjust the time required for a measurement operation for moving a welding tip to a prescribed measurement location in order to measure a wear amount.　This device 80 comprises: a measurement operation execution unit 70 that controls a mobile machine 58 so as to execute a measurement operation for moving a welding tip in a first direction to a measurement location; a location data acquisition unit 72 that acquires the location of the mobile machine 58 when the measurement operation has been executed; and a measurement initiation location determination unit 74 that determines, as a measurement initiation location, a location for the mobile machine 58 at which the welding tip is arranged a prescribed distance apart from a first location in a second direction, which is opposite of the first direction, on the basis of the first location which is acquired during a first measurement operation. During a second measurement operation following the first measurement operation, the measurement operation execution unit 70 controls the mobile machine 58 so as to position the mobile machine 58 at the measurement initiation location and then move the welding tip in the first direction.

Description

[Technical Field]

[0001] The present disclosure relates to a device, a control device, a robot system, a method, and a computer program for measuring the amount of wear of a welding tip. [Background technology]

[0002] A device for measuring the wear amount of a welding tip is known (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-268538 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventionally, a measurement operation is performed in which a welding tip is moved to a predetermined measurement position to measure the amount of wear, but there is a demand for adjusting the time required for this measurement operation. [Means for solving the problem]

[0005] In one aspect of the present disclosure, an apparatus for measuring the amount of wear on a welding tip moved by a mobile machine includes: a measurement operation execution unit that controls the mobile machine to perform a measurement operation of moving the welding tip in a first direction to a predetermined measurement position to measure the amount of wear; a position data acquisition unit that acquires the position of the mobile machine when the measurement operation execution unit performs the measurement operation; and a measurement start position determination unit that determines, based on the first position acquired by the position data acquisition unit in the first measurement operation, a position of the mobile machine where the welding tip is positioned a predetermined distance in a second direction opposite to the first direction as a measurement start position. In a second measurement operation after the first measurement operation, the measurement operation execution unit controls the mobile machine to position the mobile machine at the measurement start position and then move the welding tip in the first direction.

[0006] In another aspect of the present disclosure, a method for measuring the amount of wear on a welding tip moved by a mobile machine includes: a processor controlling the mobile machine to perform a measurement operation to move the welding tip in a first direction to a predetermined measurement position to measure the amount of wear; acquiring the position of the mobile machine when the measurement operation is performed; determining, based on the first position acquired in the first measurement operation, a position of the mobile machine where the welding tip is positioned away from the first position in a second direction opposite to the first direction as a measurement start position; and controlling the mobile machine to position the mobile machine at the measurement start position and then move the welding tip in the first direction in a second measurement operation after the first measurement operation. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to appropriately set the start point of the movement of the welding tip in the measurement operation, thereby making it possible to appropriately adjust the time required for the measurement operation. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram of a robotic system according to one embodiment. [Figure 2] FIG. 2 is a block diagram of the robot system shown in FIG. [Figure 3] FIG. 2 is an enlarged view of the welding gun shown in FIG. [Figure 4] The robot system shown in Figure 1 and the fixture for measuring the amount of wear are shown. [Figure 5] 10 is a flowchart showing a method for measuring the amount of wear. [Figure 6] 18 is a flowchart showing an example of the flow of step S1 in FIG. 5 and step S41 in FIG. 17. [Figure 7] This shows the state when step S11 in FIG. 6 is completed. [Figure 8] This shows the state when the determination in step S13 in FIG. 6 is YES. [Figure 9]FIG. 10 is a diagram for explaining a measurement start position. [Figure 10] 10 is a flowchart showing a method for measuring the amount of wear. [Figure 11] 11 is a flowchart showing an example of the process of step S21 in FIG. 10. [Figure 12] FIG. 10 is a diagram illustrating a robot system according to another embodiment. [Figure 13] FIG. 13 is a block diagram of the robot system shown in FIG. 12. [Figure 14] FIG. 12 shows the state of the robot system when step S11 in FIG. 6 is completed. [Figure 15] 12 shows the state when the determination in step S13 in FIG. 6 is YES. [Figure 16] FIG. 13 is a diagram for explaining a measurement start position in the robot system shown in FIG. 12. [Figure 17] 10 is a flowchart showing another example of a method for measuring the amount of wear. [Figure 18] This shows the state when the determination in step S13 in FIG. 6 is YES. [Figure 19] FIG. 13 is a diagram for explaining a measurement start position in the robot system shown in FIG. 12. [Figure 20] 18 is a flowchart showing an example of the process of step S44 in FIG. 17. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In various embodiments described below, similar elements will be designated by the same reference numerals, and duplicated explanations will be omitted. First, a robot system 10 according to one embodiment will be described with reference to FIGS. 1 to 3. The robot system 10 includes a robot 12, a welding gun 14, a control device 16, and a teaching device 18.

[0010] In this embodiment, the robot 12 is a vertically articulated robot and includes 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.

[0011] Lower arm 24 is attached to rotating body 22 so as to be rotatable around a horizontal axis. Upper arm 26 is rotatably attached to the distal end of lower arm 24. Wrist 28 has wrist base 28a rotatably attached to the front end of upper arm 26, and wrist flange 28b attached to wrist base 28a so as to be rotatable around wrist axis A1.

[0012] A plurality of servo motors 30 (FIG. 2) are built into each of the robot base 20, the rotating body 22, the lower arm 24, the upper arm 26, and the wrist 28. These servo motors 30 rotate the respective movable elements of the robot 12 (i.e., the rotating body 22, the lower arm 24, the upper arm 26, the wrist 28, and the wrist flange 28b) in response to commands from the control device 16, thereby moving the welding gun 14.

[0013] Welding gun 14 is detachably attached to wrist flange 28b. As shown in Fig. 3, in this embodiment, welding gun 14 is a so-called C-type spot welding gun and includes a base 32, a fixed arm 34, a tip moving mechanism 36, a fixed welding tip 38, and a movable welding tip 40. Base 32 is connected to wrist flange 28b via a support member 42. Fixed arm 34 has a base end 34a fixed to base 32 and extends in an L-shaped curve from base end 34a to tip end 34b.

[0014] The tip moving mechanism 36 reciprocates the movable welding tip 40 along the gun axis A2 in response to commands from the control device 16. Specifically, the tip moving mechanism 36 has a movable arm 44, a servo motor 46, and a motion conversion mechanism 48. The movable arm 44 is provided on the base 32 so as to be movable along the gun axis A2. In this embodiment, the movable arm 44 is a rod-shaped member that extends linearly along the gun axis A2.

[0015] The servo motor 46 is fixed to the base 32. The motion conversion mechanism 48 includes, for example, a ball screw mechanism or a mechanism consisting of a timing belt and pulley, and converts the rotational motion of the output shaft (not shown) of the servo motor 46 into reciprocating motion along the gun axis A2 of the movable arm 44. The fixed welding tip 38 is fixed to the tip 34b of the fixed arm 34, while the movable welding tip 40 is fixed to the tip 44a of the movable arm 44. The fixed welding tip 38 and the movable welding tip 40 are arranged so as to be aligned on the gun axis A2.

[0016] When welding the workpiece, tip movement mechanism 36 rotates servo motor 46 in response to a command from control device 16, thereby moving movable welding tip 40 along gun axis A2 toward fixed welding tip 38 and clamping the workpiece between movable welding tip 40 and fixed welding tip 38. Next, current is applied to fixed welding tip 38 and movable welding tip 40 in response to a command from control device 16, thereby spot welding the workpiece clamped between fixed welding tip 38 and movable welding tip 40.

[0017] The control device 16 controls the operations of the robot 12 and the welding gun 14. As shown in Fig. 2, the control device 16 is a computer having a processor 50, a memory 52, and an I / O interface 54. The processor 50 has a CPU, a GPU, or the like, and is communicatively connected to the memory 52 and the I / O interface 54 via a bus 56, and performs calculations for a wear amount measurement function, which will be described later, while communicating with these components.

[0018] The memory 52 has RAM, ROM, or the like, and temporarily or permanently stores various data used in the arithmetic processing executed by the processor 50 and various data generated during the arithmetic processing. The I / O interface 54 has, 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 communication under instructions from the processor 50. In this embodiment, the servo motors 30 and 46 and the teaching device 18 are communicatively connected to the I / O interface 54.

[0019] As shown in Fig. 1, a robot coordinate system C1 is set for the robot 12. The robot coordinate system C1 is a coordinate system for automatically controlling each movable element of the robot 12. 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. In the following description, for convenience, the positive direction of the z axis of the robot coordinate system C1 will be referred to as upward.

[0020] Meanwhile, as shown in FIG. 3, a tool coordinate system C2 is set for the welding gun 14. The tool coordinate system C2 is a control coordinate system for automatically controlling the position of the welding gun 14 in the robot coordinate system C1. In this document, "position" may refer to both position and attitude. In this embodiment, the tool coordinate system C2 is set for the welding gun 14 so that its origin is located on the fixed welding tip 38 (e.g., the center of the tip face) and its z-axis coincides with (or is parallel to) the gun axis A2. The positional relationship between the tool coordinate system C2 and the wrist flange 28b of the robot 12 is known from information such as the dimensions of the welding gun 14.

[0021] When moving the welding gun 14, the processor 50 sets a tool coordinate system C2 in the robot coordinate system C1, and sends commands to the servo motors 30 of the robot 12 to operate the movable elements of the robot 12 so as to position the welding gun 14 at a position represented by the set tool coordinate system C2. In this way, the processor 50 operates the robot 12 to position the welding gun 14 at any position in the robot coordinate system C1.

[0022] The processor 50 also sends a command to the servo motor 46 of the tip moving mechanism 36, which moves the movable arm 44 (i.e., the movable welding tip 40) along the gun axis A2 by operating the tip moving mechanism 36. In this manner, in this embodiment, the movable welding tip 40 is moved by the operation of the robot 12 and the tip moving mechanism 36. Therefore, the robot 12 and the tip moving mechanism 36 constitute a moving machine 58 that moves the movable welding tip 40.

[0023] As shown in FIG. 1, the teaching device 18 is, for example, a portable computer such as a teaching pendant or a tablet terminal device, and has a display unit 60 (LCD, organic EL display, etc.), an operation unit 62 (push button, touch sensor, etc.), a processor, and a memory (all not shown).

[0024] The operator can jog the mobile machine 58 by operating the operation unit 62 while viewing the image displayed on the display unit 60. The operator can teach the mobile machine 58 a predetermined operation by jogging the mobile machine 58 using the teaching device 18, and can thereby create an operation program for causing the mobile machine 58 to execute the predetermined operation.

[0025] Before (or after) a welding operation using welding gun 14, movable welding tip 40 (and fixed welding tip 38) may be ground with a grinder. This grinding operation causes wear on movable welding tip 40. Processor 50 measures the amount of wear W of movable welding tip 40. A method for measuring the amount of wear W will be described below.

[0026] In this embodiment, the wear amount W is measured using a fixed object 64 shown in Fig. 4. The fixed object 64 is fixed to a predetermined position in the robot coordinate system C1. Specifically, the fixed object 64 has a pillar portion 66 extending vertically and an abutment plate 68 extending horizontally from the upper end of the pillar portion 66. The abutment plate 68 has an upper surface 68a and a lower surface 68b that are disposed approximately parallel to the xy plane (i.e., the horizontal plane) of the robot coordinate system C1.

[0027] First, the processor 50 executes the flow shown in Fig. 5. The flow shown in Fig. 5 starts when the processor 50 receives an initial measurement start command CM1 from an operator, a higher-level controller, or the operation program PG. This initial measurement start command CM1 is issued, for example, when a new, unworn movable welding tip 40 is attached to the movable arm 44. In step S1, the processor 50 executes a first measurement operation MO1. This step S1 will be described with reference to Fig. 6.

[0028] After starting step S1, in step S11, processor 50 executes a first approach operation to position mobile machine 58 at a predetermined taught position TP. Specifically, processor 50 causes robot 12 to move welding gun 14 and position it at first taught position TP1, and also causes tip moving mechanism 36 to move movable arm 44 at speed V1 and place movable arm 44 at second taught position TP2. Thus, in this embodiment, the taught positions TP of mobile machine 58 include the first taught position TP1 at which robot 12 should position welding gun 14, and the second taught position TP2 at which tip moving mechanism 36 should position movable arm 44.

[0029] 7 shows the positional relationship between the welding gun 14 and the fixed object 64 when the mobile machine 58 is positioned at the teaching position TP. At this time, the contact plate 68 of the fixed object 64 is positioned between the fixed welding tip 38 and the movable welding tip 40, and the movable welding tip 40 is spaced upward a predetermined distance from the upper surface 68a of the contact plate 68.

[0030] Further, the fixed welding tip 38 is separated downward by a predetermined distance from the lower surface 68b of the contact plate 68, and the gun axis A2 is substantially orthogonal to the upper surface 68a of the contact plate 68. When the moving machine 58 is positioned at the teaching position TP, the fixed welding tip 38 may contact the lower surface 68b without contact force.

[0031] The first teaching position TP1 of the robot 12 is determined as position data (specifically, coordinates) representing the position (specifically, the origin position and the directions of each axis) of the tool coordinate system C2 shown in FIG. 7. Further, the second teaching position TP2 of the tip moving mechanism 36 is determined as the rotational position (or rotational angle) of the servo motor 46.

[0032] For example, the operator may teach the robot 12 an operation of positioning the welding gun 14 at the position shown in FIG. 7 by operating the teaching device 18 to jog the robot 12, thereby obtaining the position data of the first teaching position TP1. The position data of the teaching positions TP (the first teaching position TP1 and the second teaching position TP2) is stored in advance in the memory 52.

[0033] Referring again to FIG. 6, in step S12, the processor 50 moves the movable welding tip 40 in the first direction toward the measurement position MP. In the present embodiment, the measurement position MP is the position of the upper surface 68a of the contact plate 68. The processor 50 operates the tip moving mechanism 36 to advance the movable arm 44 from the second teaching position TP2 at a speed V2, thereby moving the movable welding tip 40 downward (the first direction) at a speed V2. Here, this speed V2 is set to a value smaller than the above-described speed V1 (V2 < V1).

[0034] In step S13, the processor 50 determines whether the movable welding tip 40 has reached the measurement position MP. Specifically, the processor 50 determines whether the load torque τ of the servo motor 46 is a predetermined threshold value τ thAfter the start of step S12, the tip of the movable welding tip 40 comes into contact with the upper surface 68a of the contact plate 68, whereby the movable welding tip 40 is positioned at the measurement position MP (i.e., the position of the upper surface 68a).

[0035] 8 shows the movable welding tip 40 positioned at the measurement position MP. When the tip of the movable welding tip 40 comes into contact with the upper surface 68a, the load torque τ applied to the servo motor 46 increases. Therefore, by monitoring the load torque τ, it is possible to determine whether the movable welding tip 40 has reached the measurement position MP (in other words, whether it has come into contact with the upper surface 68a).

[0036] As one example, the processor 50 may obtain, as the load torque τ, a feedback current from the servo motor 46. As another example, the welding gun 14 may further include a torque sensor that detects the torque applied to the output shaft of the servo motor 46, and the processor 50 may obtain, as the load torque τ, the detected value of the torque sensor.

[0037] In step S13, the processor 50 determines whether the load torque τ is greater than or equal to the threshold τ th If it exceeds (τ ≥ τ th ), the processor 50 determines that the movable welding tip 40 has reached the measurement position MP (i.e., YES), and proceeds to step S14. th If so, the determination is NO, and step S13 is looped.

[0038] In step S14, the processor 50 stops the servo motor 46, thereby stopping the movable welding tip 40. Then, the processor 50 ends step S1 and proceeds to step S2 in Fig. 5. By this step S1, the movable welding tip 40 is positioned stationary at the measurement position MP (upper surface 68a).

[0039] As described above, in this embodiment, in the first measurement operation MO1, the processor 50 controls the movable machine 58 so that, after positioning the movable machine 58 at the taught position TP in step S11, the movable welding tip 40 is moved downward by the tip moving mechanism 36 in step S12. Therefore, the processor 50 functions as a measurement operation execution unit 70 (FIG. 2) that controls the movable machine 58 to execute the measurement operation MO.

[0040] 5 again, in step S2, the processor 50 acquires the position P1 of the movable machine 58. Specifically, the processor 50 acquires the rotational position (or rotational angle) of the servo motor 46 at the end of step S1 as position data indicating the position P1 of the movable arm 44 of the movable machine 58. As an example, the welding gun 14 may further include a rotation detector (encoder, Hall element, or the like) that detects the rotational position of the servo motor 46, and the processor 50 may acquire the detection value of the rotation detector as the position P1.

[0041] As another example, the welding gun 14 may further include a position detector (such as a linear scale or a displacement sensor) that detects the position of the movable arm 44 in the direction of the gun axis A2, and the processor 50 may acquire the detected value of the position detector as the position P1. Thus, in this embodiment, the processor 50 functions as a position data acquisition unit 72 (FIG. 2) that acquires the position P1 of the mobile machine 58.

[0042] In step S3, the processor 50 determines a measurement start position SP1 based on the position P1 acquired in step S2. The measurement start position SP1 will be described below with reference to Fig. 9. In Fig. 9, the movable arm 44 positioned at position P1 in step S1 is shown by a dotted line 44', and the movable welding tip 40 when the movable arm 44 is positioned at position P1 (i.e., the measurement position MP) is shown by a dotted line 40'.

[0043] 9, the movable arm 44 disposed at the measurement start position SP1 and the movable welding tip 40 when the movable arm 44 is disposed at the measurement start position SP1 are each indicated by a solid line. As shown in Fig. 9, when the movable arm 44 is disposed at the measurement start position SP1, the movable welding tip 40 is disposed at a predetermined distance δ above the movable arm 44 when it is disposed at position P1, and is disposed at a distance δ below the movable arm 44 when it is disposed at the second teaching position TP2 (Fig. 7).

[0044] Based on position P1 acquired in step S2, processor 50 determines measurement start position SP1 as a position of movable arm 44 at which movable welding tip 40 is moved upward by a distance δ from when movable arm 44 is positioned at position P1. As an example, this distance δ is determined based on a positioning error α by which movable machine 58 positions movable welding tip 40. Positioning error α is a distance by which movable welding tip 40 may deviate from a predetermined target position when movable machine 58 positions the movable welding tip 40 at the target position, and can be expressed as a numerical range of ±α (for example, α = 0.1 mm).

[0045] For example, the processor 50 determines the distance δ as a value (δ=α) that matches the positioning error α, and determines the measurement start position SP1 of the movable arm 44 as a position that is separated upward from position P1 by the distance δ=α. Alternatively, the processor 50 may determine the distance δ as a value (δ=κα) obtained by multiplying the positioning error α by a predetermined coefficient κ. In this way, in this embodiment, the processor 50 functions as a measurement start position determiner 74 (FIG. 2) that determines the measurement start position SP.

[0046] After executing the flow of FIG. 5, the processor 50 repeatedly executes a series of operations, including moving the welding tips 38 and 40 using the mobile machine 58, spot welding the welding points on the workpiece (not shown) using the welding tips 38 and 40, and then grinding the welding tips 40 (and 38).

[0047] During this series of operations, the processor 50 executes the flow shown in Fig. 10 each time a grinding operation is performed. The flow shown in Fig. 10 starts when the processor 50 receives a measurement start command CM2 from an operator, a higher-level controller, or the operation program PG. This measurement start command CM2 can be issued each time a grinding operation is performed on the welding tips 38, 40.

[0048] In step S21, the processor 50 functions as the measurement operation execution unit 70 and executes the n-th measurement operation MO n (n=2, 3, 4, . . . ) is executed. This step S21 will be described with reference to Fig. 11. In the flow shown in Fig. 11, the same processes as those in the flow shown in Fig. 6 are assigned the same step numbers, and duplicated descriptions will be omitted.

[0049] After starting step S21, the processor 50 executes step S11 described above and positions the movable machine 58 at the taught position TP shown in Fig. 7. In step S31, the processor 50 executes a second approach operation. Specifically, the processor 50 operates the tip moving mechanism 36 to move the movable arm 44 from the second taught position TP2 to the most recently determined measurement start position SP n‐1 Move it at a speed of V3.

[0050] For example, when the flow shown in FIG. 10 is executed after the flow shown in FIG. 5, the n-th measurement operation MO n The number "n" that identifies the measurement start position SP is n=2. n‐1 becomes the measurement start position SP1 described above. Therefore, in step S31, the processor 50 moves the movable arm 44 from the second taught position TP2 to the measurement start position SP1. Note that the speed V3 at which the movable arm 44 is moved in step S31 may be set to the same value as the above-mentioned speed V1, or may be set to a value different from the speed V1. Furthermore, the speed V3 may be set to a value greater than the above-mentioned speed V2.

[0051] In step S32, the processor 50 moves the movable welding tip 40 in a first direction toward the measurement position MP. Specifically, the processor 50 operates the chip moving mechanism 36 to move the movable arm 44 forward from the measurement start position SP n‐1 at a speed V4, thereby moving the movable welding tip 40 downward at a speed V4. This speed V4 is set to a value smaller than the above-described speeds V1 and V3 (V4 < V1, V4 < V3). Note that the speed V4 may be set to the same value as the above-described speed V2.

[0052] Thus, in this step S32, the processor 50 controls the moving machine 58 (movable arm 44) to move the movable welding tip 40 downward after positioning the moving machine 58 (movable arm 44) at the measurement start position SP n‐1 . After step S32, the processor 50 sequentially executes the above-described steps S13 and S14.

[0053] As described above, the processor 50 moves the movable arm 44 (that is, the movable welding tip 40) along the gun axis A2 from the second teaching position TP2 (FIG. 7) to the measurement start position SP n‐1 (for example, the position of the solid line 40 in FIG. 9) at a speed V3, and then moves from the measurement start position SP n‐1 to the measurement position MP (the position shown in FIG. 8) at a speed V4 (< V3) by executing steps S11, S31, S32, and S13.

[0054] Referring to FIG. 10 again, in step S22, the processor 50 functions as the position data acquisition unit 72 and acquires the position P n of the moving machine 58 (specifically, the movable arm 44) at the end of step S21 in the same manner as in step S2 described above.

[0055] In step S23, the processor 50 functions as the measurement start position determination unit 74 and determines the measurement start position SP n . Specifically, the processor 50 uses the position P acquired in the most recent step S22n Based on this, similarly to step S3 described above, the movable arm 44 moves to the position P n The measurement start position SP is a position of the movable arm 44 at which the movable welding tip 40 is moved upward by a distance δ compared to when the movable arm 44 is disposed at the second teaching position TP2 (FIG. 7), while the movable welding tip 40 is moved downward compared to when the movable arm 44 is disposed at the second teaching position TP3 (FIG. 7). n (See Figure 9)

[0056] In step S24, the processor 50 acquires the wear amount W. Specifically, the processor 50 acquires the wear amount W for the (n-1)th measurement operation MO n-1 The position P obtained when n-1 (first position) and the nth measurement operation MO n The position P obtained when n (second position) and based on this, the (n-1)th measurement operation MO n-1 and the nth measurement operation MO n The amount of wear W caused by the grinding work carried out between n‐1 Get.

[0057] For example, when the flow shown in Figure 10 is executed after the flow shown in Figure 5, n = 2, so in this step S24, the processor 50 will obtain the amount of wear W1 that occurred between the first measurement operation MO1 and the second measurement operation MO2 based on the position P1 obtained in the above-mentioned step S2 and the position P2 obtained in the most recent step S22.

[0058] As an example, the processor 50 may n-1 The rotational position RP of the servo motor 46 is obtained as n-1 and position P n The rotational position RP of the servo motor 46 is obtained as n Difference Δ RP (=RP n -RP n-1 ) is calculated, and the difference Δ RP is converted into the amount of displacement in the direction of the gun axis A2, the amount of wear W n‐1 Get.

[0059] Thus, in this embodiment, the processor 50 calculates the position P n-1 and P n Based on the wear amount W n‐1 Thereafter, processor 50 repeatedly executes the flow of FIG. 10 every time it receives measurement start command CM2 (i.e., every time it performs grinding work) during the series of work including welding work and grinding work.

[0060] 5 and 10 in accordance with an operation program PG. The operation program PG is a computer program that includes various commands (e.g., commands to the servo motors 30 and 46) for causing the processor 50 to execute the flows shown in FIGS.

[0061] The operation program PG may be provided in a form recorded on a computer-readable recording medium (memory 52), such as a semiconductor memory, a magnetic recording medium, or an optical recording medium. The operation program PG is created by an operator using, for example, the teaching device 18, and is stored in advance in the memory 52.

[0062] As described above, in this embodiment, the processor 50 functions as the measurement operation execution unit 70, the position data acquisition unit 72, the measurement start position determination unit 74, and the wear amount acquisition unit 76 to measure the wear amount W. Therefore, the measurement operation execution unit 70, the position data acquisition unit 72, the measurement start position determination unit 74, and the wear amount acquisition unit 76 constitute a device 80 ( FIG. 2 ) that measures the wear amount W. The device 80 (the measurement operation execution unit 70, the position data acquisition unit 72, the measurement start position determination unit 74, and the wear amount acquisition unit 76) are functional modules realized by, for example, a computer program (for example, the operating program PG) executed by the processor 50.

[0063] In this embodiment, the processor 50 performs the (n-1)th measurement operation MO n-1 The position P obtained by n-1 (First position) based on the measurement start position SP n‐1is determined (step S3 or S23), and the n-th measurement operation MO n In this state, the moving machine 58 (movable arm 44) is moved to the measurement start position SP n‐1 After positioning the movable welding tip 40, the movable welding tip 40 is moved downward (in the first direction) (steps S31 and S32).

[0064] In this way, the measurement start position SP n By determining each time, the measurement operation MO n As a result, the starting point of the operation of moving the movable welding tip 40 to the measurement position MP at a speed V4 can be set appropriately. n It is possible to appropriately adjust the time required for

[0065] The processor 50 also determines the measurement start position SP n-1 The movable welding tip 40 is positioned at P n-1 The n-th measurement operation MO is determined as the position of the mobile machine 58 that is disposed at a distance δ above (in the second direction) the n-th measurement operation MO. n In the second approach operation, the mobile machine 58 is moved to the measurement start position SP n‐1 When the movable welding tip 40 is positioned at the measurement position MP (upper surface 68a), the distance δ and the wear amount W n‐1 The sum of (δ+W n‐1 ) in the upward direction. Therefore, the movable welding tip 40 can be prevented from reaching the measurement position MP (that is, from coming into contact with the upper surface 68a) during the second approach operation.

[0066] In this embodiment, the processor 50 also performs the measurement operation MO n In this case, the movable welding tip 40 is moved downward until it abuts against the fixed object 64 (specifically, the upper surface 68a) arranged at the measurement position MP, and the position P of the movable machine 58 when the movable welding tip 40 abuts against the fixed object 64 at the measurement position MP is measured. n has been obtained.

[0067] According to this configuration, the movable machine 58 (movable arm 44) can be stopped reliably by bringing the movable welding tip 40 into contact with the upper surface 68a, and the operation of the movable machine 58 to bring the movable welding tip 40 into contact with the fixed object 64 can be easily and reproducibly performed. n can be obtained stably with high accuracy.

[0068] In this embodiment, the processor 50 also n After the mobile machine 58 is positioned at the teaching position TP (first approach operation), the measurement start position SP n‐1 At this time, the processor 50 moves the movable machine 58 (movable arm 44) from the taught position TP to the measurement start position SP n‐1 After moving at a speed V3 (first speed) to the measurement start position SP n‐1 The object is moved downward from the center at a speed V4 (second speed) lower than the speed V3 (step S32).

[0069] In this embodiment, in step S13, the load torque τ of the servo motor 46 is set to a value equal to or smaller than the threshold value τ th , and stops the movable arm 44 in step S14. However, due to delays in the torque response of the servo motor 46, etc., variations may occur in the stopping position of the movable arm 44 in step S14.

[0070] In order to suppress such variations and accurately measure the wear amount W, it is necessary to set the speed at which the welding tip 40 reaches the measurement position MP during the measurement operation MO relatively low. Conventionally, each time a measurement operation MO is performed, the movable machine 58 is positioned at a previously taught position TP, and then the movable welding tip 40 is moved from the taught position TP to the measurement position MP at a relatively low speed V4.

[0071] According to this embodiment, the movable welding tip 40 is moved to the measurement start position SP n‐1 Since it can be moved at a relatively high speed V3 up to nTherefore, the cycle time of the work can be reduced and the work efficiency can be improved. n‐1 By moving the movable welding tip 40 at a relatively low speed V4 from the measurement position MP to the measurement position MP, the position P of the movable machine 58 when the movable welding tip 40 reaches the measurement position MP is calculated. n Since it is possible to accurately obtain the amount of wear W n can be obtained with high accuracy.

[0072] In this embodiment, the processor 50 determines the measurement start position SP n-1 is determined as the position of the movable machine 58 (movable arm 44) at which the movable welding tip 40 moves downward from the taught position TP (second taught position TP2). According to this configuration, the movement of the movable welding tip 40 in steps S31 and S32 is in the direction of one axis (gun axis A2).

[0073] Therefore, steps S31 and S32 can be performed by the operation of the movable arm 44 which is movable in one axial direction, and therefore the measurement operation MO n The operation program PG for the position P of the single-axis movable arm 44 and the structure of the moving machine 58 can be simplified. n Since the amount of wear W can be detected with high accuracy by a rotation detector provided in the servo motor 46, n can be detected with high accuracy.

[0074] In this embodiment, the (n-1)th measurement operation MO n-1 (For example, in the first measurement operation MO1), the movable machine 58 is positioned at the teaching position TP, and then the movable welding tip 40 is moved downward (step S11 in FIG. 6 or FIG. 11). n Since the common teaching position TP is used in the first approach operation executed in n The operating program PG for the

[0075] 11 (that is, when the processor 50 moves the movable arm 44 to the measurement start position SP n‐1 The moving machine 58 (specifically, the tip moving mechanism 36) may be controlled so that the movable arm 44 is temporarily stopped when the tip is placed on the work piece 41, and then the movable arm 44 is moved downward in step S32.

[0076] In this case, the distance δ may be determined based on the run-up distance β required for the tip moving mechanism 36 to accelerate the speed V of the movable arm 44 from zero to the speed V4 in step S32. For example, the distance δ may be determined as a value equal to the run-up distance β (δ=β), or may be determined as a value obtained by multiplying the run-up distance β by a predetermined coefficient κ (δ=κβ). In this case, the processor 50 determines the measurement start position SP in steps S3 and S23. n At position P n The position is determined as a position spaced upward by a distance δ (=β or κβ) from the target point.

[0077] Alternatively, the processor 50 may continuously execute step S32 without stopping the movable arm 44 when completing the above-described step S31. In this case, the processor 50 moves the movable arm 44 to the measurement start position SP n‐1 After (or before) placing the movable arm 44 at the speed V3, the speed V of the movable arm 44 is reduced from the speed V3 to the speed V4, and step S32 is executed.

[0078] In this case, the distance δ may be determined based on the run-up distance ε required for the tip moving mechanism 36 to decelerate the movable arm 44 from the speed V3 to the speed V4. For example, the distance δ may be determined as a value equal to the run-up distance ε (δ=ε), or may be determined as a value obtained by multiplying the run-up distance ε by a predetermined coefficient κ (δ=κε).

[0079] Next, a robot system 90 according to another embodiment will be described with reference to Figures 12 and 13. The robot system 90 differs from the above-described robot system 10 in that it further includes an object detection sensor 92. The object detection sensor 92 is communicatively connected to the I / O interface 54 of the control device 16. The object detection sensor 92, for example, irradiates electromagnetic waves (infrared rays, etc.) at the measurement position MP and detects an object that passes through the measurement position MP in a non-contact manner. When the object detection sensor 92 detects an object at the measurement position MP, it transmits an object detection signal to the control device 16.

[0080] The control device 16 (specifically, the processor 50) of the robot system 90 measures the wear amount W by, for example, executing the flows shown in Figures 5 and 10. Below, we will explain the processes in the flows of Figures 5 and 10 executed by the processor 50 of the robot system 90 that are different from those in the robot system 10 described above.

[0081] 6 or 11, the processor 50 of the robot system 90 executes a first approach operation to position the mobile machine 58 at a predetermined teaching position TP. Fig. 14 shows the positional relationship between the welding gun 14 and the object detection sensor 92 when the mobile machine 58 is positioned at the teaching position TP in this embodiment.

[0082] 14, the movable welding tip 40 is moved upward by a predetermined distance from the measurement position MP of the object detection sensor 92, and the gun axis A2 is approximately perpendicular to the measurement position MP (the propagation direction of the electromagnetic waves emitted by the object detection sensor 92). The processor 50 causes the robot 12 to move the welding gun 14 and position it at a first taught position TP1 represented by the tool coordinate system C2 shown in Fig. 14, and also causes the tip moving mechanism 36 to move the movable arm 44 at a speed V1 to position it at a second taught position TP2.

[0083] 6 or 11, the processor 50 determines whether the movable welding tip 40 has reached the measurement position MP. Specifically, the processor 50 determines whether an object detection signal has been received (the object detection signal has turned ON) from the object detection sensor 92. As a result of the movable welding tip 40 being moved downward in step S12 or S32 executed before this step S13, the movable welding tip 40 reaches the measurement position MP (i.e., the electromagnetic wave propagation region) as shown in FIG.

[0084] Then, the object detection sensor 92 turns on the object detection signal and transmits it to the control device 16. By monitoring the object detection signal, the processor 50 can determine whether the movable welding tip 40 has reached the measurement position MP. When the processor 50 receives the object detection signal from the object detection sensor 92, the processor 50 determines YES and proceeds to step S14.

[0085] Then, in step S3 or S23, the processor 50 calculates the most recently acquired position P n Based on this, the movable arm 44 moves to the position P n The measurement start position SP is the position of the movable arm 44 at which the movable welding tip 40 is moved upward by a distance δ from when the movable welding tip 40 is positioned at the dotted line 40′. n Determine.

[0086] Thus, in this embodiment, the processor 50 performs the measurement operation MO n In step S2 or S22, the movable welding tip 40 is moved downward until the object detection sensor 92 detects the movable welding tip 40 at the measurement position MP. n According to this configuration, the load applied to the movable welding tip 40 and the tip moving mechanism 36 can be reduced compared to when the movable welding tip 40 is brought into contact with the fixed object 64 described above.

[0087] Next, another example of the method for measuring the wear amount W executed by the processor 50 of the robot system 90 will be described with reference to Fig. 17. The processor 50 of the robot system 90 repeatedly executes the flow shown in Fig. 17 every time the above-mentioned measurement start command CM2 is received.

[0088] In step S41, the processor 50 functions as the measurement operation execution unit 70 and executes the n-th test measurement operation MO T_n Step S41 is the same as the flow shown in Figure 6. Specifically, processor 50 executes a first approach operation in step S11 to position mobile machine 58 at taught position TP (Figure 14), and moves movable welding tip 40 downward at speed V1 in step S12. Then, when processor 50 determines YES in step S13 (i.e., when processor 50 has received an object detection signal from object detection sensor 92), processor 50 stops movable welding tip 40 in step S14.

[0089] In step S42, the processor 50 functions as the position data acquisition unit 72, and acquires the position P of the mobile machine 58 at this time, similar to step S2 described above. T_n (rotation position of the servo motor 46) is set to the test measurement position P T_n Here, the position of the movable arm 44 when the object detection sensor 92 detects the movable welding tip 40 at the measurement position MP and the processor 50 receives an object detection signal may vary depending on the speed V of the movable welding tip 40 due to factors such as a delay in the sensor response of the object detection sensor 92.

[0090] In other words, the accuracy with which the object detection sensor 92 detects the movable welding tip 40 at the measurement position MP depends on the speed V of the movable welding tip 40 passing through the measurement position MP. T_n Here is an example:

[0091] In step S43, the processor 50 functions as the measurement start position determining unit 74, and determines the trial measurement position P obtained in step S42 in the same manner as in step S3 described above. T_n Based on this, the movable arm 44 moves to the trial measurement position P T_n The main measurement start position SP is a position of the movable arm 44 at which the movable welding tip 40 is moved upward by a distance δ compared to when the movable arm 44 is disposed at the second teaching position TP2 (FIG. 14), while the movable welding tip 40 is moved downward compared to when the movable arm 44 is disposed at the second teaching position TP3 (FIG. 14). R_n Determine.

[0092] The actual measurement start position SP determined in step S43 R_n An example of this is shown in FIG. 19. In FIG. 19, in step S41, the trial measurement position P T_n The movable arm 44 positioned at the trial measurement position P is shown as a dotted line 44'. T_n The movable welding tip 40 when positioned is shown as a dotted line 40'.

[0093] On the other hand, the main measurement start position SP R_n The movable arm 44 is positioned at the main measurement start position SP R_n The solid lines indicate the movable welding tip 40 when it is positioned at the main measurement start position SP. R_n The distance δ is set so that the leading end of the movable welding tip 40 at the measurement position MP is located above the measurement position MP. For example, the distance δ may be determined based on the positioning error α or the run-up distance β described above.

[0094] Referring again to FIG. 17, in step S44, the processor 50 functions as the measurement operation execution unit 70 and executes the n-th main measurement operation MO R_n Step S44 will be described with reference to Fig. 20. In the flow shown in Fig. 20, the same processes as those in the flow shown in Fig. 11 are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0095] After the start of step S44, the processor 50 executes the second approach operation in step S31'. Here, in this step S31', the processor 50 operates the chip moving mechanism 36 to move the movable arm 44 from the position at the end of step S41 (FIG. 18) to the current measurement start position SP determined in the most recent step S43 R_n (FIG. 19) at a speed V3.

[0096] In step S32', the processor 50 moves the movable welding chip 40 in the first direction toward the measurement position MP of the object detection sensor 92. Specifically, the processor 50 operates the chip moving mechanism 36 to move the movable arm 44 from the current measurement start position SP R_n forward at a speed V4 (<V3), thereby moving the movable welding chip 40 downward at a speed V4. Thereafter, the processor 50 sequentially executes steps S13 and S14.

[0097] As described above, the accuracy of the object detection sensor 92 detecting the movable welding chip 40 at the measurement position MP depends on the speed V. Therefore, by moving the movable welding chip 40 at a speed V4 lower than the speed V3 in step S32', it is possible to detect with high precision that the movable welding chip 40 has reached the measurement position MP.

[0098] Referring again to FIG. 17, in step S45, the processor 50 functions as the position data acquisition unit 72 and, similar to step S23 described above, determines the position P of the moving machine 58 (specifically, the movable arm 44) at the end of step S44 R_n (specifically, the rotational position of the servo motor 46) as the current measurement position P R_n and acquires it.

[0099] In step S46, the processor 50 functions as the wear amount acquisition unit 76 and acquires the wear amount W n‐1 . Specifically, the processor 50 executes the n-1th current measurement operation MO R_n-1 and acquires the current measurement position P R_n-1 (the third position) and the nth current measurement operation MOR_n The actual measurement position P obtained when R_n (second position) and based on this, the (n-1)th main measurement operation MO R_n-1 and the nth measurement operation MO R_n The amount of wear W caused by the grinding work carried out between n‐1 Get.

[0100] When processor 50 receives the above-described initial measurement start command CM1 (i.e., when a new, unworn movable welding tip 40 is attached to movable arm 44), it sequentially executes the flow of steps S41 to S45 in FIG. 17 to start the first trial measurement operation MO. T_1 (Step S41), and the first main measurement operation MO R_1 (Step S44), and in step S45, the actual measurement position P R_1 Get.

[0101] As described above, in this embodiment, the processor 50 performs the n-th test measurement operation MO T_n The test measurement position P obtained at T_n Based on (first position), the main measurement start position SP R_n is determined (step 43), and the nth main measurement operation MO R_n In this state, the moving machine 58 (movable arm 44) is moved to the main measurement start position SP R_n After positioning the movable welding tip 40 at the test measurement position P, the movable welding tip 40 is moved downward (in the first direction). T_n By determining the value of V4 each time, it becomes possible to appropriately set the starting point of the operation of moving the movable welding tip 40 to the measurement position MP at the speed V4 in step S44. As a result, it becomes possible to appropriately adjust the time required to measure the wear amount W.

[0102] In this embodiment, the processor 50 also performs a trial measurement operation MO T_n In this example, the movable welding tip 40 is moved at a relatively high speed V1, while the main measurement operation MO R_n In this example, the movable welding tip 40 is moved at a relatively low speed V4. T_ncan be obtained more quickly, while the actual measurement position P R_n can be obtained with higher accuracy.

[0103] In this embodiment, the movable welding tip 40 is moved at relatively high speeds V1 and V3 in the first approach operation in step S41 and the second approach operation in step S44, respectively. T_n , and this measurement operation MO R_n ) can be reduced, which reduces the cycle time of the work and improves work efficiency.

[0104] 20, the processor 50 may execute step S11 (first approach operation) before step S31'. In this case, after starting step S44, the processor 50 positions the mobile machine 58 at the taught position TP (FIG. 14) in step S11, and then moves the movable arm 44 from the taught position TP (second taught position TP2) to the main measurement start position SP in step S31'. R_n (Figure 19)

[0105] In this case, when the processor 50 completes step S31' (i.e., when the movable arm 44 is moved to the main measurement start position SP R_n After the movable arm 44 is temporarily stopped at the position where the movable arm 44 is positioned (when the movable arm 44 is positioned at the position where the movable arm 44 is positioned), the movable arm 44 may be moved downward in step S32'. The distance δ in FIG. 19 may be determined based on the above-mentioned run-up distance β (δ=β, or δ=κβ).

[0106] Alternatively, the processor 50 may continuously execute step S32' without stopping the movable arm 44 when step S31' is completed. In this case, the distance δ in FIG. 19 may be determined based on the run-up distance ε described above (δ=ε, or δ=κε).

[0107] 10, step S23 may be omitted, and the processor 50 may position the mobile machine 58 at the measurement start position SP1 initially determined at step S3 in FIG. 5 in step S31 in FIG. 11. In other words, in this case, each measurement operation MO n A common measurement start position SP1 is used for (n=2, 3, 4, . . . ).

[0108] 11, step S11 may be omitted. In this case, after starting step S21, the processor 50 executes the second approach operation of step S31, and moves the mobile machine 58 (movable arm 44) to the most recently determined measurement start position SP n‐1 At this time, the processor 50 moves the moving machine 58 (movable arm 44) directly to the measurement start position SP n‐1 The object may be moved at a speed V1 or V3 up to the target position.

[0109] In the above embodiment, the processor 50 calculates the position P of the mobile machine 58 in steps S2, S22, S42 and S45. n However, the processor 50 does not acquire the position P of the moving machine 58. n For example, the coordinate CD of the tip 44a of the movable arm 44 in the robot coordinate system C1 may be acquired as the coordinate CD.

[0110] This coordinate CD can be obtained based on the position data of the tool coordinate system C2 in the robot coordinate system C1 and the rotational position of the servo motor 46. The position data of the tool coordinate system C2 when the measurement operation is performed (i.e., at the end of steps S1, S21, S41, and S44) can be obtained from the rotational position of each servo motor 30 of the robot 12.

[0111] In the above embodiment, the processor 50 operates the tip moving mechanism 36 to move the movable arm 44 downward in steps S12, S31, S32, S31', and S32'. However, the processor 50 may operate the robot 12 to move the welding gun 14 downward in steps S12, S31, S32, S31', and S32'. In this case, the processor 50 calculates the position P of the movable machine 58 in steps S2, S22, S42, and S45. n The above coordinate CD may be obtained as follows:

[0112] In the above-described embodiment, the processor 50 determines the measurement start position SP in steps S3, S23, and S43. n , SP R_n is determined as the position of the movable arm 44 at which the movable welding tip 40 moves downward from the teaching position TP. n , SP R_n and teaching position TP will be aligned on the gun axis A2.

[0113] However, the processor 50 does not detect the measurement start position SP n , SP R_n may be determined as the position of the movable arm 44 at which the movable welding tip 40 moves away to the left or right from the teaching position TP. n , SP R_n The processor 50 operates the robot 12 to move the teaching position TP from the teaching position TP to the measurement start position SP. n , SP R_n The moving machine 58 (i.e., the movable welding tip 40) can be moved up to

[0114] In the above-described embodiment, the wear amount W is measured by moving the movable welding tip 40. However, the processor 50 can also measure the wear amount W of the fixed welding tip 38 by operating the robot 12 to execute the flow shown in FIG. 5, FIG. 10, or FIG. 17.

[0115] The wear amount acquisition unit 76 may be omitted from the device 80. For example, step S24 may be omitted from the flow of FIG. 10, and the operator may n-1 and the second position P n Refer to the wear amount W n‐1 Alternatively, step S46 may be omitted from the flow of FIG. 17, and the operator may manually determine the third position P R_n-1 and the second position P R_n Refer to the wear amount W n‐1 may be calculated manually.

[0116] Alternatively, the function of the wear amount acquisition unit 76 may be implemented in an external device of the device 80 (for example, a computer other than the control device 16, such as an external server). In this case, the processor 50 omits step S24 (or S46) and acquires the acquired first position P n-1 and the second position P n (or the third position P R_n-1 and the second position P R_n ) is transmitted to an external device via a network (Internet, LAN, etc.), and the external device receives the wear amount W n‐1 may be obtained.

[0117] In the above-described embodiment, the case has been described in which the functions of the device 80 are implemented in the control device 16. However, the functions of the device 80 may be implemented in, for example, the teaching device 18, or in an external device (external server, PC, etc.) that is capable of communicating with the control device 16. In this case, the processor of the teaching device 18 or the external device functions as the device 80.

[0118] Furthermore, the robot 12 is not limited to a vertical articulated robot, but may be any type of robot, such as a horizontal articulated robot, a parallel link robot, etc. Furthermore, in the above embodiment, the mobile machine 58 has the robot 12 and the tip moving mechanism 36, but this is not limiting, and for example, the mobile machine 58 may move the welding tip 38 or 40 using a plurality of ball screw mechanisms.

[0119] Furthermore, the welding gun 14 is not limited to a C-type spot welding gun, but may be, for example, an X-type spot welding gun or any other type of welding gun. While the present disclosure has been described above through the embodiments, the above-described embodiments do not limit the invention according to the claims. [Explanation of symbols]

[0120] 10,90 Robot System 12. Robot 14 Welding gun 16 Control device 36 Chip moving mechanism 38,40 Welding Tip 58 Mobile Machinery 70 Measurement operation execution unit 70 72 Position data acquisition unit 74 Measurement start position determination unit 76 Wear amount acquisition unit

Claims

1. A device for measuring the amount of wear of a welding tip moved by a mobile machine, comprising: a measurement operation execution unit that controls the mobile machine to execute a measurement operation of moving the welding tip in a first direction to a predetermined measurement position in order to measure the wear amount; a position data acquisition unit that acquires the position of the mobile machine when the measurement operation execution unit executes the measurement operation; a measurement start position determiner that determines, based on the first position acquired by the position data acquirer in the first measurement operation, a position of the mobile machine where the welding tip is positioned a predetermined distance away from the first position in a second direction opposite to the first direction, as a measurement start position; In a second measurement operation after the first measurement operation, the measurement operation execution unit After positioning the mobile machine at a predetermined teaching position, positioning the mobile machine at the measurement start position; An apparatus for controlling the movable machine to move the welding tip in the first direction after positioning the movable machine at the measurement start position.

2. 2. The device according to claim 1, further comprising a wear amount acquisition unit that acquires the amount of wear that has occurred between the first measurement operation and the second measurement operation based on the first position and the second position acquired by the position data acquisition unit in the second measurement operation.

3. a sensor for detecting a fixed object or the welding tip is provided at the measurement position; 3. The device according to claim 1, wherein the measurement operation executing unit moves the welding tip in the first direction during the measurement operation until the welding tip abuts against the fixed object at the measurement position or until the sensor detects the welding tip at the measurement position.

4. 2. The device according to claim 1, further comprising a wear amount acquisition unit that acquires the amount of wear that has occurred between the third measurement operation and the second measurement operation, based on the third position acquired by the position data acquisition unit in the third measurement operation before the first measurement operation and the second position acquired by the position data acquisition unit in the second measurement operation.

5. a sensor for detecting the welding tip is provided at the measurement position; The apparatus according to claim 4 , wherein the measurement operation execution unit moves the welding tip in the first direction in the measurement operation until the sensor detects the welding tip at the measurement position.

6. The device according to any one of claims 1 to 5, wherein the measurement start position determiner determines the measurement start position as a position of the mobile machine at which the welding tip moves away from the taught position in the first direction.

7. The apparatus according to any one of claims 1 to 6, wherein the measurement operation execution unit controls the mobile machine so as to position the mobile machine at the taught position and then move the welding tip in the first direction in the first measurement operation.

8. 8. The device according to claim 1, wherein, in the second measurement operation, the measurement operation executing unit moves the mobile machine from the taught position to the measurement start position at a first speed, and moves the mobile machine from the measurement start position in the first direction at a second speed lower than the first speed.

9. A control device comprising the device according to any one of claims 1 to 8, wherein the control device moves the welding tip using the mobile machine to perform an operation of welding a workpiece with the welding tip.

10. a moving machine for moving the welding tip; A robot system comprising: a control device according to claim 9 that controls the mobile machine.

11. 1. A method for measuring wear on a welding tip moved by a mobile machine, comprising: The processor: controlling the moving machine to perform a measurement operation of moving the welding tip in a first direction to a predetermined measurement position for measuring the amount of wear; Acquire the position of the mobile machine when the measurement operation is performed; determining, based on the first position acquired in the first measurement operation, a position of the mobile machine where the welding tip is positioned away from the first position in a second direction opposite to the first direction, as a measurement start position; In a second measurement operation after the first measurement operation, After positioning the mobile machine at a predetermined teaching position, positioning the mobile machine at the measurement start position; The method further comprises controlling the movable machine to move the welding tip in the first direction after positioning the movable machine at the measurement start position.

12. A computer program product causing the processor to perform the method of claim 11.

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