Wrist device and robot

Abstract

A wrist device is provided. The wrist device includes a first element (5) rotatably connected to an arm (2) about a fifth axis (L5), a second element (6) rotatably connected to the first element (5) about a sixth axis (L6), a fifth motor (M5) that rotationally drives the first element (5), a sixth motor (M6) that rotationally drives the second element (6), a fifth transmission mechanism (T5) that transmits a driving force of the fifth motor (M5) to the first element (5), and a sixth transmission mechanism (T6) that transmits a driving force of the sixth motor (M6) to the second element (6). The sixth transmission mechanism (T6) has a first gear (84) that reduces a rotational speed of the driving force after the first gear (84) in a direction of transmission of the driving force, the first gear (84) being rotatably supported by the arm (2), and a second gear (85) that is rotatably supported by the first element (5) and engaged with the first gear (84).

Description

TECHNICAL FIELD

[0001] The technology disclosed herein relates to a wrist device and a robot. BACKGROUND

[0002] So far, a wrist device connected to an arm of a robot is known. For example, a wrist device divided into a first element and a second element is disclosed in Patent Literature 1. The first element is rotatably connected to an arm. The second element is rotatably connected to the first element. A drive source of the first element and a drive source of the second element are provided to the arm. Therefore, a transmission portion that transmits a driving force to the first element is provided to the arm. On the other hand, a transmission portion that transmits a driving force to the second element is provided from the arm to the first element.

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2014-213437 SUMMARY

[0004] However, in the wrist device described above, since the transmission portion to the second element is provided from the arm to the first element, when the first element rotates, the transmission portion to the second element is affected thereby. That is, the portion of the transmission portion to the second element that is provided to the first element rotates together with the first element. As a result, it is possible that the rotation of the second element is induced by the rotation of the first element.

[0005] In view of the above, an object of the technology disclosed herein is to reduce the rotation of the second element induced by the rotation of the first element.

[0006] The wrist device disclosed herein includes a first element rotatably connected to an arm about a prescribed first rotation axis, a second element rotatably connected to the first element about a prescribed second rotation axis, a first driving portion provided to the arm that rotationally drives the first element, a second driving portion provided to the arm that rotationally drives the second element, a first transmission portion provided to the arm that transmits a driving force of the first driving portion to the first element, and a second transmission portion provided from the arm to the first element that transmits a driving force of the second driving portion to the second element. The second transmission portion has a first drive gear that decelerates the driving force after the first drive gear in a transmission direction of the driving force. The first drive gear is rotatably supported by the arm.

[0007] The robot disclosed herein includes an arm having a plurality of links rotatably connected to each other and the wrist device connected to the arm.

[0008] According to the wrist device, it is possible to reduce the rotation of the second element induced by the rotation of the first element.

[0009] According to the robot, it is possible to reduce the rotation of the second element induced by the rotation of the first element. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a side view of a vertical multi-joint robot.

[0011] Figure 2 is a plan view of a vertical multi-joint robot.

[0012] Figure 3 is a cross-sectional view of a second end portion of a third link in a plane including a fifth axis and a sixth axis, and a wrist device. DETAILED DESCRIPTION

[0013] Hereinafter, an exemplary embodiment will be described in detail with reference to the drawings.

[0014] Figure 1 is a side view of a vertical multi-joint robot 100. Figure 2 is a plan view of a vertical multi-joint robot 100. The vertical multi-joint robot (hereinafter, also simply referred to as "robot") 100 includes a base 1, an arm 2 rotatably connected to the base 1 in a horizontal direction, and a wrist device 4 provided at a front end of the arm 2. Note that in Figure 2 , the illustration of the base 1 is omitted. The vertical multi-joint robot 100 is one example of a robot.

[0015] The arm 2 has a plurality of links rotatably connected to each other about axes extending in a horizontal direction. Specifically, the arm 2 has a first link 21, a second link 22, and a third link 23. The arm 2 also has a base 20. The base 20 is installed in the base 1. In each link, one end portion in the length direction is referred to as a first end portion, and the other end portion in the length direction is referred to as a second end portion.

[0016] The first end portion 21a of the first link 21 is rotatably connected to the base 20 about a first axis L1 extending in a vertical direction via a first joint J1. The first end portion 22a of the second link 22 is rotatably connected to the second end portion 21b of the first link 21 about a second axis L2 extending in a horizontal direction via a second joint J2. The first end portion 23a of the third link 23 is rotatably connected to the second end portion 22b of the second link 22 about a third axis L3 extending in a horizontal direction via a third joint J3. The third link 23 is divided into a rear portion 23c including the first end portion 23a and a front portion 23d including the second end portion 23b. The front portion 23d is rotatably connected to the rear portion 23c about a fourth axis L4 extending in the length direction of the third link 23 via a fourth joint J4.

[0017] The arm 2 is driven by a plurality of motors. The plurality of motors, which are omitted from illustration, include a first motor that rotationally drives the first link 21, a second motor that rotationally drives the second link 22, a third motor that rotationally drives the rear portion 23c of the third link 23, and a fourth motor that rotationally drives the front portion 23d of the third link 23. Also, the arm 2 has a transmission mechanism for transmitting the driving force of each motor.

[0018] The wrist device 4 includes a first element 5 that is rotationally connected to the arm 2 about a fifth axis L5, and a second element 6 that is rotationally connected to the first element 5 about a sixth axis L6. A hand or a gun or the like end effector is attached to the second element 6. The fifth axis L5 is an example of the first rotational axis, and the sixth axis L6 is an example of the second rotational axis.

[0019] In detail, the first element 5 is rotationally connected to the second end portion 23b of the third link 23 about the fifth axis L5 that is orthogonal to the fourth axis L4 via a fifth joint J5. The second element 6 is rotationally connected to the first element 5 about the sixth axis L6 that is orthogonal to the fifth axis L5 via a sixth joint J6. The sixth axis L6 is arranged in line with the fourth axis L4.

[0020] The wrist device 4 also includes a fifth motor M5 that is provided to the arm 2 to rotationally drive the first element 5, a sixth motor M6 that is provided to the arm 2 to rotationally drive the second element 6, a fifth transmission mechanism T5 that is provided to the arm 2 to transmit the driving force of the fifth motor M5 to the first element 5, and a sixth transmission mechanism T6 that is provided from the arm 2 to the first element 5 to transmit the driving force of the sixth motor M6 to the second element 6. The fifth motor M5 and the sixth motor M6 are, for example, servo motors. The fifth motor M5 is an example of the first driving portion, and the sixth motor M6 is an example of the second driving portion. The fifth transmission mechanism T5 is an example of the first transmission portion, and the sixth transmission mechanism T6 is an example of the second transmission portion.

[0021] The front portion 23d of the third link 23 is formed in a hollow shape and has an internal space. The first element 5 is formed in a hollow shape and has an internal space. The fifth motor M5, the sixth motor M6, and the fifth transmission mechanism T5 are housed in the internal space of the front portion 23d of the third link 23. The sixth transmission mechanism T6 is housed in the internal space of the front portion 23d of the third link 23 and the internal space of the first element 5. The output shaft m5 of the fifth motor M5 and the output shaft m6 of the sixth motor M6 extend in a direction orthogonal to the length direction of the arm 2 (in detail, the length direction of the third link 23). Also, the output shaft m5 of the fifth motor M5 and the output shaft m6 of the sixth motor M6 extend in parallel with the fifth axis L5.

[0022] Next, the structure of the wrist device 4 is described in detail. Figure 3 is a cross-sectional view of the second end portion 23b of the third link 23 in a plane including the fifth axis L5 and the sixth axis L6 and the wrist device 4.

[0023] The second end portion 23b of the third link 23 is formed in a bifurcated shape. In detail, a first support portion 3A and a second support portion 3B are provided in the second end portion 23b. The first support portion 3A and the second support portion 3B are arranged at intervals in the direction of the fifth axis L5. The first support portion 3A and the second support portion 3B rotatably support the first element 5 about the fifth axis L5.

[0024] The first element 5 has a first shaft 51 that penetrates the first support portion 3A and extends to the inside of the first support portion 3A. A gear 52 is provided in the first shaft 51. The gear 52 is a spur gear. The axis of the first shaft 51 and the axis of the gear 52 coincide with the fifth axis L5. The first shaft 51 is rotatably supported about the fifth axis L5 by a first bearing 31 provided in the first support portion 3A. The gear 52 is disposed inside the first support portion 3A.

[0025] In this way, the first element 5 is rotatably supported by the first support portion 3A about the fifth axis L5.

[0026] A fifth transmission mechanism T5 is provided inside the first support portion 3A. The fifth transmission mechanism T5 is, for example, a gear train. The gear 52 is one gear of the gear train of the fifth transmission mechanism T5. The driving force of the fifth motor M5 is transmitted to the gear 52 via the fifth transmission mechanism T5. Thus, the first element 5 rotates about the fifth axis L5 relative to the first support portion 3A.

[0027] The first element 5 has a connecting portion 53 to which the second element 6 is connected. The connecting portion 53 is formed in a substantially cylindrical shape with the sixth axis L6 as the axis.

[0028] The second element 6 is formed in a substantially cylindrical shape extending with the sixth axis L6 as the axis. The second element 6 penetrates the first element 5 in the connecting portion 53 and extends to the inside of the first element 5. A flange 61 is provided in the end portion of the second element 6 that is exposed to the outside of the first element 5. The second element 6 is rotatably supported about the sixth axis L6 by a first bearing 54 provided in the first element 5.

[0029] The sixth transmission mechanism T6 is provided from the third link 23 to the first element 5. The sixth transmission mechanism T6 has a first gear 84 rotatably supported by the arm 2 and a second gear 85 rotatably supported by the first element 5 and engaged with the first gear 84, which reduces the rotational speed of the driving force a plurality of times after the first gear 84 in the direction of transmission of the driving force. The first gear 84 is an example of a first drive gear, and the second gear 85 is an example of a first driven gear.

[0030] The sixth transmission mechanism T6 further has a third gear 86 rotatably supported by the first element 5 and rotated by the rotation of the second gear 85 and a gear 62 provided in the second element 6 and engaged with the third gear 86. The first gear 84 and the second gear 85 and the third gear 86 and the gear 62 reduce the rotational speed of the driving force.

[0031] The sixth transmission mechanism T6 further has a first pulley (omitted from the drawing), a second pulley 82, and a synchronous belt 83.

[0032] The first pulley is provided on the output shaft m6 of the sixth motor M6. The synchronous belt 83 is wound around the first pulley and the second pulley 82. The first pulley, the second pulley 82, and the synchronous belt 83 are disposed inside the third link 23. The second pulley 82 is disposed inside the second support portion 3B.

[0033] The first gear 84 is coaxially connected to the second pulley 82 via a rotation shaft 87. The first gear 84 is a spur gear. The axis of the second pulley 82, the axis of the first gear 84, and the axis of the rotation shaft 87 coincide with the fifth shaft L5. The second pulley 82 and the first gear 84 are rotatably supported about the fifth shaft L5 via the second bearing 32 and the third bearing 33 provided in the second support portion 3B. The first gear 84 is disposed inside the first element 5.

[0034] The second gear 85 is engaged with the first gear 84. The second gear 85 is a spur gear. The second gear 85 and the third gear 86 are coaxial and non-rotatably connected to each other. The third gear 86 is a pinion gear. The second gear 85 and the third gear 86 are rotatably supported about the shaft L7 parallel to the fifth shaft L5 via the second bearing 55 and the third bearing 56 provided in the first element 5. That is, the first gear 84 and the second gear 85 have rotation axes parallel to each other.

[0035] The gear 62 has an axis coaxial with the sixth shaft L6 and is non-rotatably provided in the second element 6. In detail, the gear 62 is provided at the end inside the first element 5 in the second element 6. The gear 62 is a ring gear.

[0036] The third gear 86 is engaged with the gear 62 of the second element 6. The third gear 86 and the gear 62 are hypoid gears. That is, the third gear 86 and the gear 62 have rotation axes located in mutually twisted positions.

[0037] In the sixth transmission mechanism T6 configured as such, the driving force of the sixth motor M6 is transmitted in the order of the first pulley, the synchronous belt 83, the second pulley 82, the first gear 84, the second gear 85, the third gear 86, and the gear 62. Thus, the second element 6 rotates relative to the first element 5 about the sixth axis L6. At this time, the rotational speed of the driving force of the sixth motor M6 is decelerated when transmitted from the first pulley 81 to the second pulley 82 via the synchronous belt 83, when transmitted from the first gear 84 to the second gear 85, and when transmitted from the third gear 86 to the gear 62. The deceleration ratio of the first gear 84 and the second gear 85 is larger than that of the third gear 86 and the gear 62. The deceleration ratio of the third gear 86 and the gear 62 is larger than that of the first pulley 81 and the second pulley 82.

[0038] The axis of the first gear 84 in the sixth transmission mechanism T6, which transmits the driving force from the third link 23 side to the first element 5 side, coincides with the rotation axis of the first element 5, i.e., the fifth axis L5. Thus, when the first element 5 rotates about the fifth axis L5, the axial distance between the first gear 84 and the second gear 85 supported by the first element 5 remains constant. That is, even if the first gear 84 supported by the third link 23 is disposed inside the first element 5, the first element can rotate about the fifth axis L5 while maintaining the engagement between the first gear 84 and the second gear 85.

[0039] However, when the first element 5 rotates, the second gear 85 rotates about the fifth axis L5. If the first gear 84 does not rotate, the second gear 85 rotates about the axis L7 because the second gear 85 rotates about the first gear 84 in the state of engagement with the first gear 84. When the second gear 85 rotates about the axis L7, the second element 6 rotates about the sixth axis L6. Hereinafter, the rotation of the second element 6 induced by the rotation of the first element 5 will be referred to as "induced rotation".

[0040] In the arm 2 configured as such, the rotational speed of the driving force is decelerated twice at the rear side closer to the transmission direction of the driving force of the sixth motor M6, compared with the first gear 84 disposed coaxially with the rotation axis of the first element 5, i.e., the fifth axis L5. Specifically, the rotational speed of the driving force is decelerated once when transmitted from the first gear 84 to the second gear 85, and is decelerated again when transmitted from the third gear 86 to the gear 62. Thus, the relative rotation of the first gear 84 and the second gear 85 generated when the first element 5 rotates is greatly reduced and transmitted to the second element 6. As a result, it is possible to reduce the induced rotation of the second element 6.

[0041] Note that the sixth motor M6 rotates the first gear 84 to cancel the induced rotation of the second element 6 when the first element 5 rotates. That is, the sixth motor M6 rotates the first gear 84 in cooperation with the rotation of the second gear 85 around the fifth shaft L5 so that the second gear 85 does not rotate around the shaft L7. Thus, the induced rotation of the second element 6 is reduced or canceled. As described above, by increasing the reduction ratio between the first gear 84 and the gear 62, the position accuracy of the second element 6 when the induced rotation of the second element 6 is canceled can be improved. That is, in the sixth transmission mechanism T6, an error can occur due to backlash of gears and the like. This error can also occur when the first gear 84 is rotated to cancel the induced rotation of the second element 6. However, since the reduction ratio between the first gear 84 and the gear 62 is large, the error transmitted to the second element 6 is reduced. As a result, the position accuracy of the second element 6 is improved.

[0042] As described above, the wrist device 4 includes the first element 5 rotatably connected to the arm 2 around a prescribed fifth shaft L5 (first rotation axis), the second element 6 rotatably connected to the first element 5 around a prescribed sixth shaft L6 (second rotation axis), the fifth motor M5 (first driving portion) provided to the arm 2 and rotationally driving the first element 5, the sixth motor M6 (second driving portion) provided to the arm 2 and rotationally driving the second element 6, the fifth transmission mechanism T5 (first transmission portion) provided to the arm 2 and transmitting the driving force of the fifth motor M5 to the first element 5, the sixth transmission mechanism T6 (second transmission portion) provided from the arm 2 to the first element 5 and transmitting the driving force of the sixth motor M6 to the second element 6, the sixth transmission mechanism T6 having the first gear 84 (first driving gear) rotatably supported by the arm 2 and the second gear 85 (first driven gear) rotatably supported by the first element 5 and engaged with the first gear 84 and reducing the rotational speed of the driving force after the first gear 84 in the direction of transmission of the driving force.

[0043] Also, the robot 100 includes the arm 2 having a plurality of links rotatably connected to each other like the first link 21, the second link 22, and the third link 23, and the wrist device 4 connected to the arm 2.

[0044] According to these structures, since the sixth motor M6 that rotates to drive the second element 6 is provided to the arm 2, the driving force of the sixth motor M6 is transmitted to the sixth transmission mechanism T6 provided to the first element 5 from the arm 2, therefore, when the first element 5 rotates, the portion of the sixth transmission mechanism T6 provided to the first element 5 rotates together with the first element 5. Specifically, since in the sixth transmission mechanism T6, the first gear 84 is rotatably supported by the arm 2, and the second gear 85 is rotatably supported by the first element 5, therefore, the portion of the sixth transmission mechanism T6 after the second gear 85 can rotate together with the first element 5. Here, the sixth transmission mechanism T6 decelerates the rotational speed of the driving force after the first gear 84 (i.e., the meshing of the first gear 84 and the second gear 85 can be included). Therefore, even if the portion of the sixth transmission mechanism T6 after the second gear 85 rotates with the rotation of the first element 5, the influence on the second element 6 caused by this rotation is reduced according to the deceleration ratio after the first gear 84. As a result, the induced rotation of the second element 6 can be reduced.

[0045] The first gear 84 and the second gear 85 decelerate the rotational speed of the driving force.

[0046] According to this structure, even if the second gear 85 rotates around the first gear 84 with the rotation of the first element 5, the rotation of the second gear 85 around its rotation axis, i.e., the shaft L7, caused by this rotation is reduced. The rotation of the second gear 85 around the shaft L7 caused by the rotation of the first element 5 is the cause of the induced rotation of the second element. Since the rotation of the second gear 85 around this shaft L7 is reduced, the induced rotation of the second element 6 can be effectively reduced.

[0047] The sixth transmission mechanism T6 decelerates the rotational speed of the driving force multiple times after the first gear 84 in the transmission direction of the driving force.

[0048] According to this structure, the deceleration ratio after the first gear 84 of the sixth transmission mechanism T6 is large. Therefore, even if the portion of the sixth transmission mechanism T6 after the second gear 85 rotates with the rotation of the first element 5, the influence on the second element 6 caused by this rotation is greatly reduced according to the deceleration ratio after the first gear 84. As a result, the induced rotation of the second element 6 can be further reduced.

[0049] Also, the sixth transmission mechanism T6 further has a third gear 86 rotatably supported by the first element 5 and rotated by the rotation of the second gear 85, and a gear 62 provided to the second element 6 and meshing with the third gear 86, the first gear 84 and the second gear 85 and the third gear 86 and the gear 62 decelerate the rotational speed of the driving force.

[0050] According to this structure, the rotational speed of the driving force is decelerated at least twice by the first gear 84 and the second gear 85 and the third gear 86 and the gear 62.

[0051] Further, the first gear 84 is rotatably supported by the arm 2 around the fifth shaft L5.

[0052] According to this structure, when the first element 5 rotates around the fifth shaft L5, the shaft interval between the first gear 84 and the second gear 85 is kept constant. Therefore, the first element 5 can rotate around the fifth shaft L5 in a state where the first gear 84 and the second gear 85 are properly engaged.

[0053] The gear 62 has an axis coaxial with the sixth shaft L6 and is non-rotatably provided in the second element 6.

[0054] According to this structure, the final rotational speed of the driving force of the sixth motor M6 is decelerated and transmitted to the second element 6. Therefore, the error generated when the driving force is transmitted through the sixth transmission mechanism T6 is finally reduced and transmitted to the second element 6. As a result, the position accuracy of the second element 6 can be improved.

[0055] The second gear 85 and the third gear 86 are coaxial with each other and non-rotatably connected.

[0056] According to this structure, there is no gear other than the second gear 85 and the third gear 86 between the first gear 84 and the gear 62. Therefore, the structure in which the rotational speed of the driving force is decelerated multiple times after the first gear 84 can be realized with as few gears as possible. As a result, the structure can be simplified, and the error generated when the driving force is transmitted can be reduced.

[0057] More specifically, the first gear 84 and the second gear 85 have rotational axes parallel to each other, and the third gear 86 and the gear 62 have rotational axes located in a twisted position with respect to each other.

[0058] According to this structure, the rotational axis of the driving force can be flexibly changed when the driving force of the sixth motor M6 is transmitted to the second element 6.

[0059] More specifically, the first gear 84 and the second gear 85 are spur gears, and the third gear 86 and the gear 62 are hypoid gears.

[0060] Further, the reduction ratio of the first gear 84 and the second gear 85 is larger than the reduction ratio of the third gear 86 and the gear 62.

[0061] According to this structure, since the structure of the spur gear is simpler than that of the hypoid gear, a gear pair with a larger reduction ratio can be easily realized.

[0062] Further, the sixth motor M6 has an output shaft m6 extending in a direction orthogonal to the length direction of the arm 2.

[0063] According to this structure, the output shaft m6 of the sixth motor M6 can be arranged in parallel with the rotation axis of the first element 5, i.e., the fifth axis L5. The fifth axis L5 is also the rotation axis of the first gear 84. That is, the output shaft m6 of the sixth motor M6 and the rotation axis of the first gear 84 can be arranged in parallel. As a result, the driving force of the sixth motor M6 can be transmitted to the first gear 84 via a gear, a pulley, with a simple structure without changing the direction of the rotation axis.

[0064]

[0065] As described above, the embodiments are described as examples of the technology disclosed in this application. However, the technology disclosed in this application is not limited to this, but can also be applied to embodiments with appropriate changes, substitutions, additions, omissions, etc. Further, each of the constituent elements described in the embodiments can be combined as a new embodiment. Further, among the constituent elements described in the drawings and the detailed description, not only the constituent elements necessary to solve the problems but also the constituent elements that can be included for the purpose of exemplifying the technology can be included. Therefore, it should not be immediately considered that the constituent elements that are not necessary are necessary only because they are described in the drawings and the detailed description.

[0066] For example, the fifth transmission mechanism T5 and the sixth transmission mechanism T6 are not limited to the above-described structure. The fifth transmission mechanism T5 can adopt any structure as long as it is provided in the arm and can transmit the driving force of the first driving portion to the first element. The sixth transmission mechanism T6 can adopt any structure as long as it is provided from the arm to the first element and can transmit the driving force of the second driving portion to the second element. For example, the fifth transmission mechanism T5 is not limited to a gear train, but can be a structure in which a driving force is transmitted by a pulley and a synchronous belt, or a structure in which a pulley and a synchronous belt and a gear are combined together. The sixth transmission mechanism T6 is not limited to a structure in which a pulley and a synchronous belt and a gear are combined together, but can be a structure in which only a gear train is provided.

[0067] Further, although the first gear 84 and the second gear 85 are engaged in the first element 5, they are not limited to this. The first gear 84 and the second gear 85 can be engaged in the inside of the arm 2 (for example, the inside of the third link 23). At that time, an opening having a size capable of preventing interference with the second gear 85 is formed in the arm 2 so that the second gear 85 can be rotated around the fifth axis L5 by the rotation of the first element 5. Alternatively, the first gear 84 and the second gear 85 can be engaged in the gap between the arm 2 and the first element 5 (i.e., the outside of the arm 2 and the outside of the first element 5).​

[0068] The first gear 84 and the second gear 85 are not limited to spur gears. The first gear 84 and the second gear 85 can also be bevel gears or hypoid gears, etc.

[0069] The third gear 86 and the gear 62 are not limited to hypoid gears. The third gear 86 and the gear 62 can also be bevel gears. That is, the third gear 86 and the gear 62 can also have mutually intersecting axes of rotation. Alternatively, the third gear 86 and the gear 62 can also be spur gears.

[0070] A gear other than the second gear 85 and the third gear 86 can also be provided between the first gear 84 and the gear 62.

[0071] The rotational speed of the driving force can not be reduced multiple times, but only once, after the first gear 84 in the direction of transmission of the driving force of the sixth motor M6. For example, when the driving force is reduced by the first gear 84 and the second gear 85, the third gear 86 and the gear 62 can also transmit the driving force at a constant speed or at an increased speed. Alternatively, when the driving force is reduced by the third gear 86 and the gear 62, the first gear 84 and the second gear 85 can also transmit the driving force at a constant speed or at an increased speed.

[0072] The output shaft m5 of the fifth motor M5 and the output shaft m6 of the sixth motor M6 can also not be parallel to the fifth shaft L5. For example, the output shaft m5 of the fifth motor M5 and the output shaft m6 of the sixth motor M6 can also be parallel to the length direction of the third link 23.

[0073] The structure of the arm 2 is not limited to the above-described structure. For example, the number of links of the arm 2 is not limited to three. The links can be one, two, or four or more.

[0074] Furthermore, the robot 100 is not limited to a vertical multi-joint robot. For example, the robot 100 can also be a horizontal multi-joint robot.

[0075] (Explanation of Symbols)

[0076] 100 - vertical multi-joint robot (robot); 2 - arm; 21 - first link (link); 22 - second link (link); 23 - third link (link); 4 - wrist device; 5 - first element; 6 - second element; 62 - gear (second driven gear); 84 - first gear (first drive gear); 85 - second gear (first driven gear); 86 - third gear (second drive gear); L5 - fifth shaft (first axis of rotation); L6 - sixth shaft (second axis of rotation); M5 - fifth motor (first drive portion); M6 - sixth motor (second drive portion); T5 - fifth transmission mechanism (first transmission portion); T6 - sixth transmission mechanism (second transmission portion).

Claims

1. A wrist device, characterized in that... : The wrist device includes a first element, a second element, a first drive unit, a second drive unit, a first transmission unit, and a second transmission unit. The first element is rotatably connected to an arm about a predetermined first rotation axis, and the second element is rotatably connected to the first element about a predetermined second rotation axis. The first drive unit is disposed on the arm and drives the first element to rotate. The second drive unit is disposed on the arm and drives the second element to rotate. The first transmission unit is disposed on the arm and transmits the driving force of the first drive unit to the first element. The second transmission unit is disposed from the arm to the first element and transmits the driving force of the second drive unit to the second element. The second transmission unit has a first drive gear and a first driven gear. Following the first drive gear in the direction of drive force transmission, the rotational speed of the drive force is reduced. The first drive gear is rotatably supported by the arm, and the first driven gear is rotatably supported by the first element and meshes with the first drive gear. When the first drive unit is driven without driving the second drive unit, the first driven gear supported on the first element rotates around the non-rotating first drive gear, and the first drive gear and the first driven gear are in a speed reduction relationship. The second transmission part further includes a second drive gear and a second driven gear. The second drive gear is rotatably supported by the first element and rotates by the rotation of the first driven gear. The second driven gear is disposed on the second element and meshes with the second drive gear. The first drive gear, the first driven gear, the second drive gear, and the second driven gear reduce the rotational speed of the driving force. The first driven gear and the second driving gear are coaxially connected and non-rotatably. The wrist device can reduce the rotation of the second element induced by the rotation of the first element.

2. The wrist device according to claim 1, characterized in that... : The second transmission unit decelerates the rotational speed of the driving force multiple times after the first drive gear in the direction of driving force transmission.

3. The wrist device according to claim 1 or 2, characterized in that... : The first drive gear is rotatably supported by the arm about the first rotation axis.

4. The wrist device according to claim 1 or 2, characterized in that... : The second driven gear has a shaft coaxial with the second rotating shaft and is non-rotatably disposed in the second element.

5. The wrist device according to claim 1 or 2, characterized in that... : The first driving gear and the first driven gear have mutually parallel rotational shafts. The second drive gear and the second driven gear have rotating shafts that cross each other or are in a position of mutual torsion.

6. The wrist device according to claim 5, characterized in that... : The first driving gear and the first driven gear are spur gears. The second driving gear and the second driven gear are bevel gears or hypoid gears.

7. The wrist device according to claim 5, characterized in that... : The reduction ratio of the first drive gear and the first driven gear is greater than the reduction ratio of the second drive gear and the second driven gear.

8. The wrist device according to claim 1 or 2, characterized in that... : The second drive unit has an output shaft extending in a direction orthogonal to the length direction of the arm.

9. A robot, characterized in that... : The robot includes an arm and a wrist assembly, the arm having a plurality of links rotatably connected to each other, and the wrist assembly being connected to the arm and described in any one of claims 1 to 8.

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