Articulated robot

Abstract

An articulated robot (1) includes: a robot arm (6 - 10); a wrist portion (5) disposed at a tip of the robot arm (6 - 10); an end effector (2) attached to the wrist portion (5); and a cable (13) connecting the end effector (2) and an end effector controller (14) to each other, the end effector controller (14) being disposed in a fixed manner on ground, and a cable fixing member (12A) supporting a middle portion of the cable (13) is disposed at a position apart from the robot arm (6 - 10).

Description

[DESCRIPTION][Title of Invention]ARTICULATED ROBOT[Technical Field]

[0001] The present disclosure relates to an articulated robot.[Background Art]

[0002] Articulated robots for work having an end effector (e.g., a paint spray gun or a spot welding gun) attached to a tip thereof are frequently used in many industrial fields. For example, a 6- axis vertically articulated robot described in PTL 1 includes a swivel base (basic first axis) that swivels about a vertical shaft on a base, a lower arm (basic second axis) that is attached to the swivel base and swings in a front-rear direction, an upper arm (basic third axis) that is attached to a tip of the lower arm and swings in an up-down direction, and a wrist portion (wrist first axis to wrist third axis) that is attached to a tip of the upper arm and has three degrees of freedom. An end effector attached to a tip of the wrist portion via an attachment portion can take any posture at any position, and flexibly perform work such as painting or welding.

[0003] An end-effector-side cable (such as a paint hose or an electric wire cable) led out from the end effector is connected to a robot-side cable (such as a paint hose or an electric wire cable) extending from the robot. These cables receive excessive stress (of bending or pulling) during operation of the robot. Accordingly, in the articulated robot described in PTL 1, the end- effector-side cable and the robot-side cable are connected to each other by a terminal on an end effector side with respect to the wrist portion (also referred to as the attachment portion).

[0004] The number of times the wrist portion or the attachment portion disposed on a tip side of the robot arm with respect to the upper arm is driven is greater than that of other portions of the articulated robot. Thus, the end-effector-side cable disposed on the tip side with respect to the upper arm is frequently bent, and receives stress more frequently than the robot-side cable. When the cables are connected to each other by a terminal on the end effector side with respect to the wrist portion, bending, wear, and damage of the end-effector-side cable is suppressed. Thus, the number of times troublesome work of replacing the end-effector-side cable is performed is reduced, and the maintainability increases.[Citation List][Patent Literature]

[0005] [PTL 1] lapanese Unexamined Patent Application Publication No. 2015-58515[Summary of Invention][Technical Problem]

[0006] In PTL 1, the robot-side cable is disposed along the lower arm and the upper arm. Thus, it is inevitable that the robot-side cable is bent or damaged by actions of the lower arm and the upper arm. That is, the robot-side cable is prone to be bent or damaged between the swivel base (basic first axis) and the lower arm (basic second axis) or between the lower arm (basic second axis) and the upper arm (basic third axis).[Solution to Problem]

[0007] According to an embodiment of the present disclosure, an articulated robot includes a robot arm, a wrist portion, an end effector, and a cable. The wrist portion is disposed at a tip of the robot arm. The end effector is attached to the wrist portion. The cable connects the end effector and an end effector controller to each other, the end effector controller being disposed in a fixed manner on ground. A cable fixing member supporting a middle portion of the cable, is disposed at a position apart from the robot arm.[Advantageous Effects of Invention]

[0008] An articulated robot according to an embodiment of the present disclosure reduces stress on a cable and suppresses damage of the cable.[Brief Description of Drawings]

[0009] A more complete appreciation of embodiments of the present disclosure and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description with reference to the accompanying drawings.[FIG. 1] FIG. 1 is a schematic diagram of an articulated robot according to a first embodiment of the present disclosure.[FIG. 2] FIG. 2 is a schematic diagram of an articulated robot according to a second embodiment of the present disclosure.[FIG. 3] FIG. 3 is a schematic diagram of an articulated robot according to a third embodiment of the present disclosure.[FIG. 4] FIG. 4 is a schematic diagram of an articulated robot according to a fourth embodiment of the present disclosure.[FIG. 5 A] FIG. 5 A is a perspective view of an example of forceps attached to a distal end of an arm of a surgical robot.[FIG. 5B] FIG. 5B is an enlarged view of an example of the forceps illustrated in FIG. 5A. The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to beconsidered as drawn to scale unless explicitly noted. Also, identical or similar reference numerals designate identical or similar components throughout the several views. [Description of Embodiments]

[0010] In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that have a similar function, operate in a similar manner, and achieve a similar result.Referring now to the drawings, embodiments of the present disclosure are described below.As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.Embodiments of the present disclosure will be described below with reference to FIGs. 1 to 4. When a cable is disposed on an articulated robot (the articulated robot is rigged with the cable) in a fixed manner, the cable is prone to be damaged. Thus, the cable is not fixed on a robot arm behind a cable lead-out portion 11.

[0011] First EmbodimentFIG. l is a schematic diagram of an articulated robot according to a first embodiment of the present disclosure. As illustrated in FIG. 1, an articulated robot 1 (6-axis vertically articulated robot) has a plurality links and a plurality of rotation shafts JI to J6 that connect the links to each other.The articulated robot 1 includes a base 10. On the base 10, a swivel base (basic first axis) 9 is disposed via the vertical rotation shaft J6 to swivel horizontally. On the swivel base (basic first axis) 9, a lower arm (basic second axis) 8 is disposed via the horizontal rotation shaft J5 to move forward and backward.

[0012] At an upper end portion of the lower arm (basic second axis) 8, a swivel portion 7 is disposed via the horizontal rotation shaft J4. At the swivel portion 7, an upper arm (basic third axis) 6 is disposed via the rotation shaft J3. The upper arm (basic third axis) 6 moves up and down about the rotation shaft J4 and swivels about the rotation shaft J3. The upper arm 6 and the lower arm 8 may be collectively referred to as a robot arm or arm.

[0013] At a tip of the upper arm (basic third axis) 6, a wrist portion (wrist first axis to wrist third axis) 5 is disposed via the rotation shaft J2. An end effector 2 is attached to the wrist portion 5 via an attachment member 3. The attachment member 3 rotates about the rotation shaft JI.

[0014] The rotation shafts J2, J4, and J5 enable rotation in a clockwise or counterclockwise direction when viewed from the front surface of FIG. 1. The rotation shafts JI, J3, and J6 enable rotation thereabout in a near or distal direction in FIG. 1.

[0015] The end effector 2 and a connector unit 4 are attached to the attachment member 3. The connector unit 4 is equipped with a member to which a connector or terminal block for connecting a plurality of electric wires led out from the end effector 2 to a cable 13 arranged from the robot is attached. The connector unit 4 allows the connection therein.

[0016] The cable 13 is led out from the connector unit 4. The cable 13 is fixed at the cable lead-out portion 11 of the connector unit 4. The cable 13 is connected to an end effector controller 14 disposed in a fixed manner on ground, via a cable fixing member 12A standing on an upper surface of the swivel portion 7. The end effector controller 14 is implemented by control circuitry such as a central processing unit (CPU) that runs a program or an applicationspecific integrated circuit (ASIC). Since a movement (swing amount) of the swivel portion 7 is less than those of the upper arm 6 and the lower arm 8, a movement (swing amount) of the cable fixing member 12A is also small.

[0017] In terms of control of rotation at the rotation shafts, servo motors are commonly installed at the respective shafts and are controlled by a robot control apparatus, so that the end effector 2 is moved. When the end effector 2 is a discharge device that discharges a paint, the end effector 2 is moved along a to-be-painted surface of a paint target, so that painting is performed.

[0018] The life of the cable 13 ends at a break of the cable 13 caused by bending. A large number of times of bending of the cable 13 and a small bending radius adversely influence the break of the cable 13. Conversely, reducing the number of times of bending and increasing the bending radius can extend the life of the cable 13.

[0019] In the articulated robot 1 according to the present embodiment, the cable 13 is fixed at a position not causing adverse influences on the number of times of bending and the bending radius. This thus implements a reduced number of times of bending and an increased bending radius. Specifically, the cable 13 is not fixed to an arm that is parallel to the rotation shaft of the wrist portion (wrist first axis to wrist third axis) 5 to which the attachment member 3 is attached. The cable 13 is not fixed to an arm that has the rotation shaft on the same straight line as the rotation shaft of the wrist portion (wrist first axis to wrist third axis) 5 and is rotatable in a direction opposite to the rotation direction of the wrist portion 5. The cable 13 is not fixed to an arm that has the rotation shaft on the same straight line as the rotation shaft ofthe wrist portion (wrist first axis to wrist third axis) 5 and that causes a phase difference even if a rotation direction of the arm is the same as the rotation direction of the wrist portion 5.

[0020] If the cable 13 is fixed to the aforementioned arms, the number of times of bending of the cable 13 increases and the bending radius of the cable 13 decreases. This leads to a break of the cable 13. Therefore, a middle portion of the cable 13 is fixed or supported at a point other than the upper arm 6 and the lower arm 8 of the articulated robot 1 (apart from the upper arm 6 and the lower arm 8) to implement a reduced number of times of bending and an increased bending radius and thus extend the life of the cable 13.

[0021] Second EmbodimentFIG. 2 is a schematic diagram of an articulated robot 1 according to a second embodiment of the present disclosure. In FIG. 2, a cable fixing member 12B is added instead of the cable fixing member 12A and a stretchable member 15 is added to the configuration illustrated in FIG. 1.

[0022] The cable fixing member 12B has an L-shape as a whole and stands on the upper surface of the swivel portion 7. An upper portion of the cable fixing member 12B projects horizontally in a direction in which the upper arm 6 extends.

[0023] A tip of the horizontally projecting upper portion is coupled to an upper end portion of the stretchable member 15. A lower end portion of the stretchable member 15 is coupled to a slack portion 13a such that the slack portion 13a at a middle portion of the cable 13 does not touch a painting-target object 16.

[0024] An amount of slack of the slack portion 13a at the middle portion of the cable 13 depends on a distance between the cable fixing member 12B and the cable lead-out portion 11. This distance varies depending on motions at the rotation shafts JI, J2, and J3. The length of the stretchable member 15 and the height of the cable fixing member 12B are settable in accordance with a maximum change in the distance.

[0025] When the distance between the cable fixing member 12B and the cable lead-out portion 11 is the minimum, the amount of slack of the cable 13 is the maximum. The length of the stretchable member 15 and the height of the cable fixing member 12B are settable such that the slack portion 13a does not touch the painting-target object 16 even in this case. Extension and contraction of the stretchable member 15 does not hinder the movement of the end effector 2 due to the motions at the rotation shafts JI, J2, and J3.

[0026] Third EmbodimentFIG. 3 is a schematic diagram of an articulated robot 1 according to a third embodiment of the present disclosure. In FIG. 3, a cable fixing member 12C stands beside the base 10 of the articulated robot 1, and the middle portion of the cable 13 is fixed to an upper end portion of the cable fixing member 12C.

[0027] The cable fixing member 12C is disposed outside the articulated robot 1. When the articulated robot 1 has a restriction on the weight, the cable fixing member 12C can ease the restriction on the weight of the articulated robot 1.

[0028] Fourth EmbodimentFIG. 4 is a schematic diagram of an articulated robot 1 according to a fourth embodiment of the present disclosure. In this embodiment, a cable fixing member 12D stands beside the base 10 of the articulated robot 1. When the articulated robot 1 has a restriction on the weight, the cable fixing member 12D can ease the restriction on the weight of the articulated robot 1.

[0029] The cable fixing member 12D has an L-shape as a whole. An upper portion of the cable fixing member 12D projects horizontally in a direction in which the upper arm 6 extends. A tip of the horizontally projecting upper portion is coupled to an upper end portion of the stretchable member 15.

[0030] A lower end portion of the stretchable member 15 is coupled to the slack portion 13a such that the slack portion 13a at a middle portion of the cable 13 does not touch the painting -target object 16. That is, the articulated robot 1 according to the fourth embodiment illustrated in FIG. 4 corresponds to a combination of the second embodiment illustrated in FIG. 2 and the third embodiment illustrated in FIG. 3.

[0031] While the embodiments of the present disclosure have been described specifically above, the present disclosure is not limited to the embodiments described above. Needless to say, various modifications can be made within the scope of the technical spirit of the claims. For example, the configurations described herein are applicable to an articulated robot of 5 or less axes or 7 or more axes as well as 6-axis vertically articulated robot.

[0032] The articulated robot according to each of the embodiments of the present disclosure is also applicable to a surgical robot. In this case, the end effector 2 is, for example, forceps 102 illustrated in FIGs. 5 A and 5B. FIG. 5 A is a perspective view of pairs of forceps 102 attached to a distal end of an arm 101 of a surgical robot. FIG. 5B is an enlarged view of the forceps 102.

[0033] Each pair of forceps 102 is coupled to the distal end of the arm 101 via a corresponding one of joint portions 103. The joint portions 103 each have a plurality of joints and is flexibly bendable. In addition to the joint portions 103, an endoscope 104 is also coupled to the distal end of the arm 101. The endoscope 104 enables the states of the pairs of forceps 102 to be monitored.

[0034] As illustrated in FIG. 5B, the joint portion 103 includes a forceps operation cable 103a and a torque transmitting tube 103b. The forceps operation cable 103a is moved (reciprocated) in an extending direction thereof, so that the forceps 102 can be opened and closed. The torque transmitting tube 103b is rotated, so that a wrist joint which serves as a wrist portion at the tip of the joint portion 103 can be rotated.

[0035] The forceps operation cable 103a and the torque transmitting tube 103b are led out from a cable lead-out portion provided at the distal end of the arm 101 and are connected to a forceps controller which is the end effector controller as in FIGs. 1 to 4. Middle portions of the forceps operation cable 103a and the torque transmitting tube 103b are supported by a cable fixing member that is apart from the arm 101.

[0036] Preferred aspects of the present disclosure will be additionally described below.Aspect 1According to Aspect 1, an articulated robot includes a robot arm, a wrist portion, an end effector, and a cable. The wrist portion is disposed at a tip of the robot arm. The end effector is attached to the wrist portion. The cable connects the end effector and an end effector controller to each other, the end effector controller being disposed in a fixed manner on ground. A cable fixing member supporting a middle portion of the cable is disposed at a position apart from the robot arm.Aspect 2According to Aspect 2, the articulated robot of Aspect 1 includes a base, a swivel base, a lower arm, a swivel portion, an upper arm, the wrist portion, and the end effector. The swivel base is disposed on the base. The lower arm is disposed on the swivel base. The swivel portion is disposed at an upper end portion of the lower arm. The upper arm is disposed at the swivel portion. The wrist portion is disposed at a tip of the upper arm. The end effector is disposed at the wrist portion.Aspect 3According to Aspect 3, in the articulated robot of Aspect 2, the cable fixing member is disposed at the swivel portion.Aspect 4According to Aspect 4, in the articulated robot of Aspect 3, the cable fixing member is coupled to one end of a stretchable member, and an other end of the stretchable member iscoupled to the middle portion of the cable between the end effector and the cable fixing member.Aspect 5According to Aspect 5, in the articulated robot of Aspect 2, the cable fixing member stands beside the base.Aspect 6According to Aspect 6, in the articulated robot of Aspect 5, the cable fixing member is coupled to one end of a stretchable member, and an other end of the stretchable member is coupled to the middle portion of the cable between the end effector and the cable fixing member.Aspect 7According to Aspect 7, in the articulated robot of any one of Aspects 1 to 6, the end effector includes a paint spray gun, a spot welding gun, or surgical forceps.

[0037] This patent application is based on and claims priority to Japanese Patent Application No. 2023-196056, filed on November 17, 2023, in the Japan Patent Office, the entire disclosure of which is hereby incorporated by reference herein.[Reference Signs List]

[0038] 1 : articulated robot2: end effector3 : attachment member4: connector unit5: wrist portion6: upper arm (basic third axis)7: swivel portion8: lower arm (basic second axis)9: swivel base (basic first axis)10: base11 : cable lead-out portion12A-12D: cable fixing member13: cable13a: slack portion14: end effector controller15: stretchable member16: painting-target object101 : arm of surgical robot102: forceps (end effector)103: joint portion103a: forceps operation cable 103b: torque transmitting tube 104: endoscopeJ1-J6: rotation shaft

Claims

[CLAIMS]1. An articulated robot comprising: a robot arm; a wrist portion disposed at a tip of the robot arm; an end effector attached to the wrist portion; and a cable connecting the end effector and an end effector controller to each other, the end effector controller being disposed in a fixed manner on ground, wherein a cable fixing member supporting a middle portion of the cable is disposed at a position apart from the robot arm.

2. The articulated robot according to claim 1, wherein the robot art includes an upper arm and a lower arm, the articulated robot further comprising: a base; a swivel base disposed on the base, the lower arm being disposed on the swivel base; and a swivel portion disposed at an upper end portion of the lower arm, the upper arm being disposed at the swivel portion, wherein the wrist portion is disposed at a tip of the upper arm, and the end effector being disposed at the wrist portion.

3. The articulated robot according to claim 2, wherein the cable fixing member is disposed at the swivel portion.

4. The articulated robot according to claim 3, wherein the cable fixing member is coupled to one end of a stretchable member, and an other end of the stretchable member is coupled to the middle portion of the cable between the end effector and the cable fixing member.

5. The articulated robot according to claim 2, wherein the cable fixing member stands beside the base.

6. The articulated robot according to claim 5, wherein the cable fixing member is coupled to one end of a stretchable member, and another end of the stretchable member is coupled to the middle portion of the cable between the end effector and the cable fixing member.

7. The articulated robot according to any one of claims 1 to 6, wherein the end effector includes a paint spray gun, a spot welding gun, or surgical forceps.

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