Robot system and control method of robot system

Abstract

To provide a robot system that can fasten a fastening member, even when the fastening member is arranged at a narrow position.SOLUTION: A robot system 100 comprises a robot arm part 10, a screw member rotating mechanism 20 that is mounted on the robot arm part 10 and includes an engaging member 22 that engages with a screw member 1, a driving part 23 that rotates the engaging member around a central shaft line of the screw member 1, and a control part 40. The control part 40 performs a process for temporarily fastening the screw member 1 by making the driving part 23 rotate the engaging member 22, with the engaging member 22 engaging with the screw member 1, and a process for finally fastening the screw member 1 by making the robot arm part 10 rotate the engaging member 22.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] Conventionally, a robot system that fastens a fastening member by rotating the fastening member has been disclosed. Patent Document 1 discloses a robot system including a robot arm and a nut runner attached to the tip of the robot arm. The nut runner is a device that screws in a bolt by rotating the bolt. The nut runner includes a bit that engages with the head of the bolt and a motor that rotates the bit. The bit has a rod shape. The motor is disposed above the bit, and the rotation axis of the motor coincides with the axis of the rod-shaped bit. Also, in Patent Document 1, a provisional tightening process is performed at an early stage of screwing in the bolt, and a final tightening process is performed when the bolt is screwed in to a predetermined position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2017-104027 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the robot system disclosed in Patent Document 1, a nut runner performs a pre-tightening process and a final tightening process of a bolt. Generally, a final tightening process has a larger torque than a pre-tightening process. For this reason, in the robot system disclosed in Patent Document 1, the motor of the nut runner is made larger. Therefore, when the bolt is placed in a narrow position, the nut runner cannot be placed in the narrow position, which causes a problem that the nut cannot be tightened.

[0005] This disclosure has been made to solve the problems described above, and one object of this disclosure is to provide a robot system and a control method for a robot system that are capable of fastening a fastening member even when the fastening member is placed in a narrow position. [Means for solving the problem]

[0006] A robot system according to a first aspect of this disclosure includes a robot arm unit, a fastening member rotation mechanism including an engaging member attached to the robot arm unit and engaging with the fastening member, a drive unit that rotates the engaging member around a central axis of the fastening member, and a control unit that performs at least one of a process of provisionally tightening the fastening member by rotating the engaging member by the drive unit when the engaging member is engaged with the fastening member, and a process of finally tightening the fastening member by rotating the engaging member by the robot arm unit, a process of finally loosening the fastening member in a fastened state by rotating the engaging member by the robot arm unit when the engaging member is engaged with the fastening member, and a process of provisionally loosening the fastening member in a finally loosened state by rotating the engaging member by the drive unit.

[0007] As described above, the robot system according to the first aspect of the disclosure includes a control unit that performs at least one of a process of final tightening the fastening member by rotating the engaging member with the robot arm unit and a process of final loosening the fastening member by rotating the engaging member with the robot arm unit. As a result, at least one of the final tightening and final loosening, which require a relatively large torque, is performed by the robot arm unit, so that it is possible to prevent the drive unit of the fastening member rotation mechanism from becoming large. In other words, since the fastening member rotation mechanism is relatively small, even if the fastening member is arranged in a narrow position, the fastening member rotation mechanism can be arranged at the position where the fastening member is arranged. As a result, even if the fastening member is arranged in a narrow position, the fastening member can be fastened.

[0008] A control method for a robot system according to a second aspect of this disclosure includes performing at least one of the following: pre-tightening the fastening member by rotating the engaging member with a drive unit that rotates the engaging member around a central axis of the fastening member while the engaging member is engaged with the fastening member, and finally tightening the fastening member by rotating the engaging member with a robot arm unit; finally loosening the fastening member in a fastened state by rotating the engaging member with the robot arm unit while the engaging member is engaged with the fastening member, and pre-loosening the fastening member in a finally loosened state by rotating the engaging member with a drive unit.

[0009] The control method of a robot system according to a second aspect of the disclosure includes performing at least one of final tightening of a fastening member by rotating an engaging member by a robot arm unit and final loosening of the fastening member by rotating an engaging member by a robot arm unit, as described above. As a result, at least one of final tightening and final loosening, which require a relatively large torque, is performed by the robot arm unit, so that it is possible to prevent the drive unit of the fastening member rotation mechanism from becoming large. In other words, since the fastening member rotation mechanism is relatively small, even if the fastening member is arranged in a narrow position, the fastening member rotation mechanism can be arranged in the position where the fastening member is arranged. As a result, it is possible to provide a control method of a robot system capable of fastening a fastening member even if the fastening member is arranged in a narrow position. Effect of the Invention

[0010] The robot system and the control method for the robot system according to the present disclosure are capable of fastening a fastening member even when the fastening member is placed in a narrow position. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 illustrates a robotic system according to one embodiment. [Diagram 2]FIG. 13 is a diagram illustrating a screw member rotating mechanism of the robot system according to one embodiment. [Diagram 3] 3A and 3B are views showing an engagement member, a screw member, and a fastened member of a screw member rotation mechanism according to one embodiment. [Figure 4] FIG. 1 is a block diagram of a robotic system according to one embodiment. [Diagram 5] FIG. 11 is a flow diagram illustrating an operation of the robot system according to one embodiment when tightening a screw member. [Figure 6] 11A and 11B are diagrams illustrating a pre-fastening operation of the robot system according to one embodiment. [Figure 7] FIG. 13 is a diagram illustrating a final tightening operation of the robot system according to one embodiment. [Figure 8] FIG. 11 is a flowchart illustrating an operation of the robot system according to one embodiment when loosening a screw member. [Figure 9] 13A to 13C are diagrams illustrating an operation of moving a screw member upward when loosening the screw member of the robot system according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0013] (Robot Systems) The configuration of the robot system 100 will be described. As shown in FIG. 1, the robot system 100 performs at least one of provisional tightening and final tightening on the screw member 1, final loosening for loosening the screw member 1 in a fastened state, and provisional loosening for loosening the screw member 1 in a fully loosened state. In this embodiment, the robot system 100 performs both provisional tightening and final tightening, and final loosening and provisional loosening. That is, the robot system 100 provisionally tightens the screw member 1 on the fastened member 2 and then performs final tightening. In addition, the robot system 100 performs final loosening on the screw member 1 in a state fastened to the fastened member 2 and then performs provisional loosening. In addition, the fastened member 2 includes, for example, a pair of flat plate-shaped members 2a and 2b, and the pair of flat plate-shaped members 2a and 2b are fastened together by the screw member 1. In addition, the screw member 1 is an example of a fastening member.

[0014] The robot system 100 includes a robot arm unit 10, a screw member rotating mechanism 20, a force sensor 30, and a control unit 40. The screw member rotating mechanism 20 is an example of a fastening member rotating mechanism. The force sensor 30 is an example of a torque sensor.

[0015] The configuration of the robot arm unit 10 will be described. The robot arm unit 10 is a vertical multi-joint type robot arm unit 10. The robot arm unit 10 includes a plurality of joints JT. For example, the robot arm unit 10 includes six joints JT1, JT2, JT3, JT4, JT5, and JT6. That is, the robot arm unit 10 is a robot arm unit 10 having six axes. In addition, a drive unit 11 shown in FIG. 4 is disposed in each of the joints JT1 to JT6.

[0016] The following describes the configuration of the screw member rotation mechanism 20. As shown in Fig. 2, the screw member rotation mechanism 20 is a mechanism for rotating the screw member 1. The screw member rotation mechanism 20 includes an attachment member 21, an engagement member 22, a drive unit 23, a gear unit 24, a support member 25, and a movement mechanism 26.

[0017] In this embodiment, the attachment member 21 is an elongated member whose proximal end is attached to the robot arm portion 10. Further, the attachment member 21 has a plate shape. Further, the attachment member 21 includes a rectangular first portion 21a and a second portion 21b protruding from the tip of the first portion 21a. The proximal end of the first portion 21a is attached to the tip of the robot arm portion 10. Specifically, the proximal end of the first portion 21a is attached to the tip of the robot arm portion 10 via the force sensor 30. The first portion 21a rotates around the rotation axis of the joint JT6.

[0018] Further, in this embodiment, the engagement member 22 is disposed at the tip of the attachment member 21, and the drive unit 23 is disposed at the central portion of the attachment member 21. Specifically, the engagement member 22 is attached to the lower surface of the tip of the attachment member 21 via the engagement gear 24b. Further, the engagement member 22 has a column shape. As shown in FIG. 3, the tip of the engagement member 22 is inserted into the hole portion 1b of the screw head 1a of the screw member 1. The tip of the engagement member 22 and the hole portion 1b of the screw head 1a have, for example, a hexagonal shape.

[0019] As shown in FIG. 2, the drive unit 23 is disposed on the upper surface of the central portion of the attachment member 21. Further, the drive unit 23 includes a servo motor, an encoder, and a speed reducer. The drive shaft of the drive unit 23 passes through the attachment member 21, and a drive gear 24a is attached to the tip of the drive shaft of the drive unit 23.

[0020] In this embodiment, the gear portion 24 is disposed on the mounting member 21 and transmits the rotational force of the drive portion 23 to the engagement member 22. Specifically, the gear portion 24 includes a drive portion gear 24a, an engagement portion gear 24b, and an intermediate gear 24c. The drive portion gear 24a, the engagement portion gear 24b, and the intermediate gear 24c are, for example, spur gears. The engagement portion gear 24b and the intermediate gear 24c are attached to the mounting member 21. The drive portion gear 24a rotates around the A1 axis, which is the rotation axis of the drive portion 23. The engagement portion gear 24b rotates around the A2 axis, which is the rotation axis of the engagement member 22. The intermediate gear 24c is disposed between the drive portion gear 24a and the engagement portion gear 24b, and transmits the rotation of the drive portion gear 24a to the engagement portion gear 24b. In addition, two intermediate gears 24c are disposed. The two intermediate gears 24c are referred to as intermediate gears 24c1 and 24c2. The drive gear 24a meshes with the intermediate gear 24c1, the intermediate gear 24c1 meshes with the intermediate gear 24c2, and the intermediate gear 24c2 meshes with the engagement gear 24b. The intermediate gears 24c1 and 24c2 rotate around the A3 axis and the A4 axis, respectively. The intermediate gears 24c1 and 24c2 are idle gears.

[0021] In this embodiment, the diameter r1 of the drive gear 24a is equal to the diameter r2 of the engagement gear 24b. The number of teeth of the drive gear 24a is equal to the number of teeth of the engagement gear 24b. That is, the rotation of the drive unit 23 is not accelerated or decelerated between the drive gear 24a and the engagement gear 24b.

[0022] In this embodiment, the diameter r2 of the engagement gear 24b is smaller than the diameter r3 of the intermediate gear 24c. The diameter r1 of the drive gear 24a is smaller than the diameter r3 of the intermediate gear 24c. The diameter r3 of the intermediate gear 24c1 is equal to the diameter r3 of the intermediate gear 24c2.

[0023] In this embodiment, the support member 25 supports the screw head 1a of the screw member 1 from below. Specifically, the support member 25 has a flat plate shape. The tip of the support member 25 has a U-shape. The threaded portion 1c of the screw member 1 is inserted into the U-shaped tip of the support member 25. As a result, the screw head 1a of the screw member 1 is supported by the U-shaped tip of the support member 25. The support member 25 is attached to a moving mechanism 26.

[0024] In this embodiment, the moving mechanism 26 moves the support member 25 in a direction toward or away from the screw member 1. The moving mechanism 26 is attached to the lower surface of the mounting member 21. The moving mechanism 26 includes an L-shaped fixed part 26a connected to the mounting member 21 and a moving part 26b that moves relative to the fixed part 26a. The support member 25 is attached to the moving part 26b and moves together with the moving part 26b. The moving mechanism 26 is, for example, an air cylinder. A tube connected to an air source is connected to the moving mechanism 26, and the control unit 40 controls the supply of air from the air source to move the moving part 26b.

[0025] The force sensor 30 will now be described. In this embodiment, the force sensor 30 detects the torque applied to the engaging member 22. Specifically, the force sensor 30 is disposed between the tip of the robot arm unit 10 and the mounting member 21 of the screw member rotation mechanism 20. The force sensor 30 detects the torque generated when the robot arm unit 10 moves to rotate the engaging member 22. The torque detected by the force sensor 30 is transmitted to the control unit 40.

[0026] The configuration of the control unit 40 will be described. As shown in FIG. 4, the control unit 40 is a robot controller. The control unit 40 includes a main control unit 41, a servo control unit 42, and a drive circuit unit 43. The main control unit 41 and the servo control unit 42 include, for example, a CPU (Central Processing Unit). The main control unit 41 controls the drive unit 11 of the robot arm unit 10 and the drive unit 23 of the screw member rotating mechanism 20. The servo control unit 42 controls the power supplied to the drive unit 11 of the robot arm unit 10 based on a command from the main control unit 41. The drive circuit unit 43 supplies drive power to the drive unit 11 of the robot arm unit 10 and the drive unit 23 of the screw member rotating mechanism 20. The drive circuit unit 43 is disposed for each of the drive units 11 of the robot arm unit 10. Each of the drive units 11 includes a servo motor, an encoder, and a reducer.

[0027] In this embodiment, the control unit 40 coordinates the drive unit 23 of the screw member rotating mechanism 20 with the joint axes of the robot arm unit 10 as an external axis. The control unit 40 is configured to be capable of controlling seven or more axes. The control unit 40 controls the drive of a total of seven axes, including six axes of joints JT1 to JT6 of the robot arm unit 10 and one axis of the drive unit 23 of the screw member rotating mechanism 20.

[0028] Next, a control method of the robot system 100 when fastening the screw member 1 into the workpiece 2 will be described with reference to FIG.

[0029] In step S1, the control unit 40 moves the robot arm unit 10 to move the engagement member 22 of the screw member rotating mechanism 20 above the screw member 1, and engages the engagement member 22 with the screw member 1. Specifically, the tip of the engagement member 22 is inserted into the hole 1b of the screw head 1a. Note that the position of the screw member 1 may be taught to the control unit 40 in advance, and the robot arm unit 10 may be moved based on the taught position, or the robot arm unit 10 may be moved based on an image of the screw member 1 captured by the imaging unit. The screw member 1 is previously placed in the screw hole 2c of the fastened member 2.

[0030] In step S2, as shown in FIG. 6, in this embodiment, the control unit 40 executes a process of provisionally tightening the screw member 1 by rotating the engagement member 22 by the drive unit 23 in a state in which the engagement member 22 is engaged with the screw member 1. The control unit 40 rotates the engagement member 22 by the drive unit 23 so that the rotation speed of the screw member 1 during provisional tightening is greater than the rotation speed of the fastening member during final tightening. The rotation speed during provisional tightening and final tightening means the average rotation speed of the screw member 1 during provisional tightening and final tightening. In addition, the gear unit 24 rotates together with the rotation of the drive unit 23 during provisional tightening. That is, the rotation of the drive unit 23 rotates the drive unit gear 24a, the intermediate gear 24c1, the intermediate gear 24c2, and the engagement unit gear 24b, thereby rotating the engagement member 22. In addition, the engagement member 22 rotates, for example, to the A21 side.

[0031] Moreover, in this embodiment, the control unit 40 performs a process of provisionally fastening the screw member 1 within a range in which the torque applied to the screw member 1 does not exceed a predetermined first torque threshold. Specifically, the control unit 40 performs a process of provisionally fastening the screw member 1 within a range in which the current value of the current flowing through the drive unit 23 does not exceed a predetermined current threshold. In more detail, the control unit 40 monitors the current value of the current flowing from the drive circuit unit 43 to the drive unit 23, and performs a process of provisionally fastening the screw member 1 within a range in which the monitored current value does not exceed the predetermined current threshold. Furthermore, the predetermined current threshold is set in advance so that the screw member 1 does not overtighten the fastened member 2.

[0032] In step S3, as shown in FIG. 7, in this embodiment, the control unit 40 performs a process of final tightening the screw member 1 by rotating the engagement member 22 by the robot arm unit 10. Specifically, the gear unit 24 is locked when performing final tightening. In detail, when performing final tightening, the control unit 40 generates a torque in the drive unit 23 so that the drive unit gear 24a, the intermediate gear 24c1, the intermediate gear 24c2, and the engagement unit gear 24b do not rotate. As a result, the robot arm unit 10 rotates while the gear unit 24 does not rotate. As a result, the screw member 1 rotates with the rotation of the robot arm unit 10. In addition, the control unit 40 moves the robot arm unit 10 so that the engagement member 22 rotates around the A2 axis. In addition, the engagement member 22 rotates, for example, to the A21 side.

[0033] In this embodiment, the control unit 40 performs a process of final tightening the screw member 1 until the torque detected by the force sensor 30 reaches a predetermined second torque threshold. Specifically, the predetermined second torque threshold is set in advance so that the torque during final tightening is greater than the torque during temporary tightening. After the completion of final tightening, the robot arm unit 10 disengages the engagement member 22 from the screw head 1a. For example, the predetermined second torque threshold is greater than the above-mentioned predetermined first torque threshold.

[0034] When a plurality of screw members 1 are arranged, the operations from step S1 to step S3 are repeated.

[0035] Next, a method of controlling the robot system 100 when loosening the screw member 1 will be described with reference to FIG.

[0036] In step S11, as shown in FIG. 6, the control unit 40 moves the robot arm unit 10 to move the engagement member 22 of the screw member rotating mechanism 20 above the screw member 1, and engages the engagement member 22 with the screw member 1.

[0037] In step S12, in this embodiment, the control unit 40 performs a process of final loosening the screw member 1 by rotating the engaging member 22 by the robot arm unit 10 in a state in which the engaging member 22 is engaged with the screw member 1. Specifically, the gear unit 24 is locked when performing the final loosening. In detail, when performing the final loosening, the control unit 40 generates a torque in the drive unit 23 so that the gear unit 24 does not rotate, as in the case of performing the final tightening. As a result, the robot arm unit 10 rotates, but the gear unit 24 does not rotate. As a result, the screw member 1 rotates with the rotation of the robot arm unit 10. In addition, the control unit 40 moves the robot arm unit 10 so that the engaging member 22 rotates around the A2 axis. In addition, the engaging member 22 rotates, for example, toward the A22 side.

[0038] In step S13, in this embodiment, the control unit 40 rotates the engaging member 22 by the driving unit 23 to perform a process of provisionally loosening the screw member 1. The control unit 40 rotates the engaging member 22 by the driving unit 23 so that the rotation speed of the screw member 1 when provisionally loosening is performed is greater than the rotation speed of the fastening member when full loosening is performed. The rotation speed during provisional loosening and full loosening means the average rotation speed of the screw member 1 when provisionally loosening and full loosening. In addition, the gear unit 24 rotates together with the rotation of the driving unit 23 when provisional loosening is performed. That is, the rotation of the driving unit 23 rotates the driving unit gear 24a, the intermediate gear 24c1, the intermediate gear 24c2, and the engaging unit gear 24b, thereby rotating the engaging member 22. In addition, the engaging member 22 rotates, for example, to the A22 side.

[0039] In step S14, as shown in FIG. 9, in this embodiment, the control unit 40 performs a process of moving the support member 25 to a position below the screw head 1a, which is a position where the screw head 1a is supported, by the moving mechanism 26 while the screw member 1 is in a provisionally loosened state. As a result, the screw head 1a of the screw member 1 is supported at the U-shaped tip of the support member 25. Then, the control unit 40 performs a process of moving the screw member 1 upward by the robot arm unit 10 while the screw head 1a is supported by the support member 25. Here, if the screw member 1 is caught in the screw hole 2c, the screw member 1 does not move upward. If the screw member 1 is not caught in the screw hole 2c, the screw member 1 moves upward. The control unit 40 determines whether the screw member 1 is caught in the screw hole 2c based on the height of the robot arm unit 10 after the process of moving the screw member 1 upward by the robot arm unit 10 is performed. If the screw member 1 is caught in the screw hole 2c, the provisional loosening operation is repeated. After the provisional loosening is completed, the robot arm unit 10 disengages the engaging member 22 from the screw head 1a. If a plurality of screw members 1 are provided, the operations from step S11 to step S14 are repeated.

[0040] [Effects of this embodiment] The robot system 100 includes a control unit 40 that performs at least one of a process of final tightening the screw member 1 by rotating the engaging member 22 by the robot arm unit 10 and a process of final loosening the screw member 1 by rotating the engaging member 22 by the robot arm unit 10. As a result, at least one of the final tightening and final loosening, which require a relatively large torque, is performed by the robot arm unit 10, so that it is possible to prevent the drive unit 23 of the screw member rotation mechanism 20 from becoming large. That is, since the screw member rotation mechanism 20 is relatively small, even if the screw member 1 is arranged in a narrow position, the screw member rotation mechanism 20 can be arranged at the position where the screw member 1 is arranged. As a result, even if the screw member 1 is arranged in a narrow position, the screw member 1 can be fastened. In addition, compared to the case where all of the temporary tightening, final tightening, temporary loosening, and final loosening of the screw member 1 are performed by the robot arm unit 10, it is possible to shorten the time required for the work of tightening and loosening the screw member 1.

[0041] The rotation speed of the screw member 1 when performing temporary tightening is higher than the rotation speed of the screw member 1 when performing final tightening. As a result, temporary tightening is performed at a relatively high speed, and the time required for the tightening operation of the screw member 1 can be shortened. In addition, the rotation speed of the screw member 1 when performing temporary loosening is higher than the rotation speed of the screw member 1 when performing final loosening. As a result, temporary loosening is performed at a relatively high speed, and the time required for the loosening operation of the screw member 1 can be shortened.

[0042] The control unit 40 performs a process of pre-tightening within a range in which the torque applied to the screw member 1 does not exceed a predetermined first torque threshold value. This makes it possible to prevent the screw member 1 from over-tightening the fastened member 2 during pre-tightening.

[0043] The robot system 100 includes a force sensor 30 that detects the torque applied to the engagement member 22. During final tightening, the control unit 40 performs a process of final tightening the screw member 1 until the torque detected by the force sensor 30 reaches a predetermined second torque threshold value. As a result, the torque acquired from the force sensor 30 is more accurate than when the torque is acquired from the current value of the current flowing through the drive unit 23, so that the screw member 1 can be tightened with an appropriate fastening force based on the detected torque.

[0044] The screw member rotating mechanism 20 includes a gear unit 24 that transmits the rotational force of the drive unit 23 to the engaging member 22. The gear unit 24 rotates together with the drive unit 23 when performing provisional tightening, and is locked when performing final tightening, and rotates together with the drive unit 23 when performing provisional loosening, and is locked when performing final loosening. Here, when performing final tightening and final loosening, if the gear unit 24 is not locked, the rotational force of the robot arm unit 10 is not transmitted to the engaging member 22 even if the robot arm unit 10 rotates. Therefore, when performing final tightening and final loosening, by locking the gear unit 24, the rotational force of the robot arm unit 10 is transmitted to the engaging member 22, so that the engaging member 22 can be rotated by the robot arm unit 10. Therefore, the screw member 1 can be rotated by the robot arm unit 10 when performing final tightening and final loosening.

[0045] The screw member rotation mechanism 20 includes an elongated mounting member 21 whose base end is attached to the robot arm unit 10. The engagement member 22 is disposed at the tip of the mounting member 21, and the drive unit 23 is disposed at the center of the mounting member 21. As a result, even if the screw member 1 is disposed in a narrow space, the elongated mounting member 21 can be inserted into the narrow space to fasten the screw member 1. In addition, since the engagement member 22 is disposed at the tip of the mounting member 21, the screw member 1 can be fastened at a position farther away from the robot arm unit 10. In addition, since the drive unit 23 is disposed at the center of the mounting member 21, the drive unit 23 can be prevented from coming into contact with the fastened member 2, unlike when the drive unit 23 is disposed at the tip of the mounting member 21.

[0046] The screw member rotation mechanism 20 includes a gear unit 24 that is disposed on the mounting member 21 and transmits the rotational force of the drive unit 23 to the engagement member 22. The gear unit 24 includes a drive unit gear 24a that rotates around the rotation axis of the drive unit 23, an engagement unit gear 24b that rotates around the rotation axis of the engagement member 22, and an intermediate gear 24c that is disposed between the drive unit gear 24a and the engagement unit gear 24b and transmits the rotation of the drive unit gear 24a to the engagement unit gear 24b. This allows the rotation of the drive unit gear 24a to be transmitted to the engagement unit gear 24b via the intermediate gear 24c, even when the mounting member 21 is relatively long and the interval between the drive unit gear 24a and the engagement unit gear 24b is relatively large.

[0047] The diameter r1 of the drive gear 24a and the diameter r2 of the engagement gear 24b are equal. This eliminates the need to consider the speed increase ratio and speed reduction ratio between the drive gear 24a and the engagement gear 24b, unlike when the diameter r1 of the drive gear 24a and the diameter r2 of the engagement gear 24b are different, and thus makes it possible to prevent the control of the rotation of the drive unit 23 by the control unit 40 from becoming complicated.

[0048] A diameter r2 of the engagement gear 24b is smaller than a diameter r3 of the intermediate gear 24c. This makes the engagement gear 24b smaller, so that the engagement gear 24b and the engagement member 22 connected to the engagement gear 24b can easily enter a narrow space.

[0049] The robot system 100 includes a support member 25 that supports the screw head 1a of the screw member 1 from below, and a movement mechanism 26 that moves the support member 25 in a direction toward or away from the screw member 1. The control unit 40 performs a process of moving the support member 25 to below the screw head 1a by the movement mechanism 26 when the screw member 1 is in a temporarily loosened state, and a process of moving the screw member 1 upward by the robot arm unit 10 when the screw head 1a is supported by the support member 25. In this way, by moving the screw member 1 upward by the robot arm unit 10 when the screw head 1a is supported by the support member 25, it is possible to detect whether the screw member 1 is caught in the screw hole 2c.

[0050] The robot arm unit 10 includes a vertically articulated robot arm unit 10 having a plurality of joint axes. This allows the engaging member 22 to easily engage with the screw member 1 even when the screw member 1 is inclined with respect to the horizontal plane.

[0051] The control unit 40 controls the drive unit 23 of the screw member rotating mechanism 20 as an external axis in cooperation with the joint axis of the robot arm unit 10. This makes it possible to easily cause the screw member rotating mechanism 20 and the robot arm unit 10 to operate in cooperation with each other.

[0052] [Variations] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present disclosure is indicated by the claims, not by the description of the embodiments above, and further includes all modifications (variations) within the meaning and scope equivalent to the claims.

[0053] In the above embodiment, the robot system 100 performs both the provisional tightening and final tightening and the provisional loosening and final loosening, but the present disclosure is not limited to this. For example, the robot system 100 may perform only one of the provisional tightening and final tightening and the provisional loosening and final loosening.

[0054] In the above embodiment, an example has been shown in which the rotation speed of the screw member 1 during temporary tightening is greater than the rotation speed of the screw member 1 during final tightening, but the present disclosure is not limited to this. For example, the rotation speed of the screw member 1 during temporary tightening may be equal to the rotation speed of the screw member 1 during final tightening. Similarly, the rotation speed of the screw member 1 during temporary loosening may be equal to the rotation speed of the screw member 1 during final loosening.

[0055] In the above embodiment, an example has been described in which the control unit 40 monitors the current value of the current flowing from the drive circuit unit 43 to the drive unit 23, but the present disclosure is not limited to this. For example, a current detection unit that detects the current value of the current flowing to the drive unit 23 may be separately provided, and the control unit 40 may obtain the current value from the current detection unit.

[0056] In the above embodiment, the control unit 40 performs a process of final tightening the screw member 1 based on the torque detected by the force sensor 30, but the present disclosure is not limited to this. For example, the control unit 40 may perform a process of final tightening the screw member 1 based on the current value of the current flowing in the drive unit 11 of the joint JT of the robot arm unit 10.

[0057] In the above embodiment, an example has been shown in which the engaging member 22 is disposed at the tip of the mounting member 21 and the rotation axis of the engaging member 22 does not coincide with the rotation axis of the driving unit 23, but the present disclosure is not limited to this. For example, the rotation axis of the engaging member 22 may coincide with the rotation axis of the driving unit 23, as in a nut runner.

[0058] In the above embodiment, the gear unit 24 includes two intermediate gears 24c, but the present disclosure is not limited to this. For example, the number of intermediate gears 24c may be other than two, or the gear unit 24 may not include the intermediate gear 24c.

[0059] In the above embodiment, the diameter r1 of the drive gear 24a and the diameter r2 of the engagement gear 24b are equal to each other, but the present disclosure is not limited to this. For example, the diameter r1 of the drive gear 24a and the diameter r2 of the engagement gear 24b may be different from each other.

[0060] In the above embodiment, the diameter r2 of the engagement gear 24b is smaller than the diameter r3 of the intermediate gear 24c, but the present disclosure is not limited to this. For example, the diameter r2 of the engagement gear 24b and the diameter r3 of the intermediate gear 24c may be the same.

[0061] In the above embodiment, an example has been shown in which an operation for checking whether the screw member 1 is caught in the screw hole 2c is performed when loosening the screw member 1, but the present disclosure is not limited to this. For example, the operation for checking whether the screw member 1 is caught in the screw hole 2c does not have to be performed.

[0062] In the above embodiment, an example has been given in which the fastening member of the present disclosure is the screw member 1, but the present disclosure is not limited to this. In the present disclosure, the fastening member may be a fastening member other than the screw member 1.

[0063] In the above embodiment, an example has been described in which the moving mechanism 26 is disposed in the screw member rotating mechanism 20, but the present disclosure is not limited to this. For example, the moving mechanism 26 may be disposed in a part other than the screw member rotating mechanism 20, such as the robot arm section 10.

[0064] In the above embodiment, the control unit 40 is a robot controller, and the robot controller controls the joint shaft of the robot arm unit 10 and the screw member rotation mechanism 20 as an external shaft, but the present disclosure is not limited to this. For example, a control unit that controls the screw member rotation mechanism 20 as an external shaft may be arranged separately from the robot controller. Also, a control unit higher than the robot controller that controls the joint shaft of the robot arm unit 10 and the screw member rotation mechanism 20 as an external shaft may be arranged.

[0065] In the above embodiment, an example has been shown in which the robot arm unit 10 is a vertical multi-joint type robot arm unit 10, but the present disclosure is not limited to this. For example, the robot arm unit 10 may be a horizontal multi-joint type robot arm unit.

[0066] In the above embodiment, an example has been described in which the driving unit 23 is included in the screw member rotating mechanism 20, but the present disclosure is not limited to this. For example, the driving unit 23 may be disposed in the robot arm unit 10.

[0067] In the above embodiment, an example has been shown in which the gear unit 24 is locked when performing a rotational operation by the control unit 40 generating torque in the drive unit 23, but the present disclosure is not limited to this. In the present disclosure, locking of the gear unit is not limited to locking the rotation of the drive unit by servoing through torque control. For example, the gear unit may be locked by stopping the rotation of the drive unit with an electromagnetic brake or a dynamic brake. Also, a brake may be arranged to directly limit the rotation of the gear unit, rather than the rotation of the drive unit.

[0068] In the above embodiment, the robot system 100 fastens the fastened member 2 from above with the screw member 1 as the fastening member, and supports the screw head 1a from below with the support member 25 when loosening the screw member 1, but the present disclosure is not limited to this. In the present disclosure, the robot system may perform at least one of the actions of tightening and loosening the fastening member from below, side, or diagonally with respect to the fastened member. In addition, when detecting whether the fastening member is stuck, the fastening member may be moved downward or sideways other than upward while being supported by the support member. In addition, the support member may be configured to support the fastening member from above or sideways other than downward.

[0069] In the above embodiment, the control unit 40 performs a process of provisionally tightening the screw member 1 within a range in which the current value of the current flowing through the drive unit 23 does not exceed a predetermined current threshold, but the present disclosure is not limited to this. In the present disclosure, the torque applied to the screw member 1 may be detected by a torque sensor, and a process of provisionally tightening the screw member 1 within a range in which the torque does not exceed a predetermined first torque threshold may be performed.

[0070] In the above embodiment, the control unit 40 performs the process of final tightening the screw member 1 until the torque detected by the force sensor 30 reaches a predetermined second torque threshold value during final tightening, but the present disclosure is not limited to this. In the present disclosure, the control unit may perform final tightening based on the current value of the current flowing in the drive unit of the joint of the robot arm unit. That is, a current sensor that detects the current flowing in the drive unit of the joint of the robot arm unit may be arranged as a torque sensor. In addition, when the control unit as a robot controller monitors the current flowing in the drive unit of the joint of the robot arm unit, the control unit may be arranged as a current sensor, thereby making the control unit a torque sensor. In addition, a torque sensor may be arranged in the engagement member, not between the robot arm unit and the fastening member rotation mechanism. In addition, a torque sensor may be arranged in the drive unit to detect the torque applied to the engagement member. In these cases, the torque of the drive unit may be detected by a force sensor, or the current flowing in the drive unit may be detected.

[0071] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general purpose processors, special purpose processors, integrated circuits, Application Specific Integrated Circuits (ASICs), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. Processors are considered processing circuits or circuits because they include transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or the processor.

[0072] [Aspects] It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0073] (Aspect 1) A robot arm unit; a fastening member rotation mechanism attached to the robot arm portion and including an engagement member that engages with a fastening member; a drive unit that rotates the engaging member around a central axis of the fastening member; a process of provisionally fastening the fastening members by rotating the engaging member by the driving unit in a state in which the engaging member is engaged with the fastening members, and a process of final fastening the fastening members by rotating the engaging member by the robot arm unit; a final loosening process for loosening the fastening member in a fastened state by rotating the engaging member by the robot arm unit in a state in which the engaging member is engaged with the fastening member, and a provisional loosening process for loosening the fastening member in a final loosened state by rotating the engaging member by the drive unit; and a control unit that performs at least one of the above.

[0074] (Aspect 2) The robot system of aspect 1, wherein a rotational speed of the fastening member when performing the pre-fastening is greater than a rotational speed of the fastening member when performing the final fastening.

[0075] (Aspect 3) The robot system according to aspect 1 or 2, wherein a rotational speed of the fastening member when performing the temporary loosening is greater than a rotational speed of the fastening member when performing the final loosening.

[0076] (Aspect 4) The robot system according to any one of aspects 1 to 3, wherein the control unit performs the pre-tightening process within a range in which a torque applied to the fastening member does not exceed a predetermined first torque threshold.

[0077] (Aspect 5) a torque sensor for detecting a torque applied to the engaging member; The robot system according to any one of aspects 1 to 4, wherein the control unit, during the final tightening, performs a process of final tightening the fastening member until the torque detected by the torque sensor reaches a predetermined second torque threshold.

[0078] (Aspect 6) the fastening member rotation mechanism includes a gear portion that transmits a rotational force of the drive portion to the engagement member, The gear portion is The robot system according to any one of aspects 1 to 5, wherein the robot system rotates together with the drive unit when performing the provisional tightening, and is locked when performing the final tightening.

[0079] (Aspect 7) the fastening member rotation mechanism includes a gear portion that transmits a rotational force of the drive portion to the engagement member, The gear portion is The robot system according to any one of aspects 1 to 6, wherein the robot system rotates together with the drive unit when performing the provisional loosening, and is locked when performing the final loosening.

[0080] (Aspect 8) the fastening member rotation mechanism includes an elongated attachment member whose base end is attached to the robot arm portion, The engagement member is disposed at a tip of the attachment member, The robot system according to any one of aspects 1 to 7, wherein the drive unit is disposed in a central portion of the mounting member.

[0081] (Aspect 9) the fastening member rotation mechanism is disposed on the mounting member and includes a gear portion that transmits a rotational force of the drive portion to the engagement member, The gear portion is A drive gear that rotates around a rotation axis of the drive; An engagement portion gear that rotates around a rotation axis of the engagement member; 9. The robot system of claim 8, further comprising: an intermediate gear disposed between the drive gear and the engagement gear, the intermediate gear transmitting rotation of the drive gear to the engagement gear.

[0082] (Aspect 10) 10. The robot system of claim 9, wherein a diameter of the drive gear and a diameter of the engagement gear are equal.

[0083] (Aspect 11) The robot system of claim 9 or 10, wherein a diameter of the engagement portion gear is smaller than a diameter of the intermediate gear.

[0084] (Aspect 12) The fastening member includes a screw member, A support member for supporting a screw head of the screw member; a moving mechanism that moves the support member in a direction toward or away from the fastening member, The control unit is a process of moving the support member to a position supporting the screw head by the moving mechanism while the fastening member is temporarily loosened; The robot system according to any one of aspects 1 to 11, further comprising: a process of moving the screw member by the robot arm unit while the screw head is supported by the support member.

[0085] (Aspect 13) The robot system according to any one of aspects 1 to 12, wherein the robot arm unit includes a vertical multi-joint type robot arm unit having a plurality of joint axes.

[0086] (Aspect 14) The robot system according to any one of aspects 1 to 13, wherein the control unit controls the drive unit as an external axis in cooperation with a joint axis of the robot arm unit.

[0087] (Aspect 15) With the engaging member engaged with the fastening member, rotating the engaging member by a driving unit that rotates the engaging member around the central axis of the fastening member to temporarily fasten the fastening member, and rotating the engaging member by the robot arm unit to fully fasten the fastening member, With the engaging member engaged with the fastening member, rotating the engaging member by the robot arm unit to loosen the fastened fastening member, which is the full loosening, and rotating the engaging member by the driving unit to loosen the fastening member in the fully loosened state, which is the temporary loosening, Performing at least one of the above, a control method for a robot system.

Explanation of Signs

[0088] 1 Screw member (fastening member) 1a Screw head 10 Robot arm unit 20 Screw member rotation mechanism (fastening member rotation mechanism) 21 Mounting member 22 Engaging member 23 Driving unit 24 Gear unit 24a Driving unit gear 24b Engaging part gear 24c, 24c1, 24c2 Intermediate gears 25 Support member 26 Moving mechanism 40 Control unit 30 Force sensor (torque sensor) 100 Robot system

Claims

1. A robot arm unit; a fastening member rotation mechanism attached to the robot arm portion and including an engagement member that engages with a fastening member; a drive unit that rotates the engaging member around a central axis of the fastening member; a process of provisionally fastening the fastening members by rotating the engaging member by the driving unit in a state in which the engaging member is engaged with the fastening members, and a process of final fastening the fastening members by rotating the engaging member by the robot arm unit; a final loosening process for loosening the fastening member in a fastened state by rotating the engaging member by the robot arm unit in a state in which the engaging member is engaged with the fastening member, and a provisional loosening process for loosening the fastening member in a final loosened state by rotating the engaging member by the drive unit; and a control unit that performs at least one of the above.

2. The robot system according to claim 1 , wherein a rotational speed of the fastening member when performing the temporary fastening is higher than a rotational speed of the fastening member when performing the final fastening.

3. The robot system according to claim 1 , wherein a rotational speed of the fastening member when performing the temporary loosening is greater than a rotational speed of the fastening member when performing the final loosening.

4. The robot system according to claim 1 , wherein the control unit performs the pre-tightening process within a range in which a torque applied to the fastening member does not exceed a predetermined first torque threshold value.

5. a torque sensor for detecting a torque applied to the engaging member; The robot system according to claim 1 , wherein the control unit performs a process of final tightening the fastening member until the torque detected by the torque sensor reaches a predetermined second torque threshold value during the final tightening.

6. the fastening member rotation mechanism includes a gear portion that transmits a rotational force of the drive portion to the engagement member, The gear portion is The robot system according to claim 1 , wherein the robot system rotates together with the drive unit when performing the provisional fastening, and is locked when performing the final fastening.

7. the fastening member rotation mechanism includes a gear portion that transmits a rotational force of the drive portion to the engagement member, The gear portion is The robot system according to claim 1 , wherein the rotation of the drive unit occurs when the provisional loosening is performed, and the locking unit occurs when the final loosening is performed.

8. the fastening member rotation mechanism includes an elongated attachment member whose base end is attached to the robot arm portion, The engagement member is disposed at a tip of the attachment member, The robot system according to claim 1 , wherein the drive unit is disposed at a central portion of the mounting member.

9. the fastening member rotation mechanism is disposed on the mounting member and includes a gear portion that transmits a rotational force of the drive portion to the engagement member, The gear portion is A drive gear that rotates around a rotation axis of the drive; An engagement portion gear that rotates around a rotation axis of the engagement member; The robot system according to claim 8 , further comprising: an intermediate gear disposed between the drive unit gear and the engagement unit gear, the intermediate gear transmitting rotation of the drive unit gear to the engagement unit gear.

10. The robotic system of claim 9 , wherein a diameter of the drive gear and a diameter of the engagement gear are equal.

11. The robotic system of claim 9 , wherein a diameter of the engagement portion gear is smaller than a diameter of the intermediate gear.

12. The fastening member includes a screw member, A support member for supporting a screw head of the screw member; a moving mechanism that moves the support member in a direction toward or away from the fastening member, The control unit is a process of moving the support member to a position supporting the screw head by the moving mechanism while the fastening member is temporarily loosened; The robot system according to claim 1 , further comprising: a process of moving the screw member by the robot arm unit while the screw head is supported by the support member.

13. The robot system according to claim 1 , wherein the robot arm unit includes a vertical articulated robot arm unit having a plurality of joint axes.

14. The robot system according to claim 1 , wherein the control unit controls the drive unit as an external axis in cooperation with the joint axis of the robot arm unit.

15. a drive unit that rotates the engaging member around a central axis of the fastening member in a state in which the engaging member is engaged with the fastening member, thereby provisionally fastening the fastening member, and a robot arm unit that rotates the engaging member, thereby final fastening the fastening member; the final loosening of the fastening member in a fastened state by rotating the engaging member by the robot arm unit in a state in which the engaging member is engaged with the fastening member, and the provisional loosening of the fastening member in a final loosened state by rotating the engaging member by the drive unit; and performing at least one of the following:

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