Robot

Abstract

To provide a robot whose movable region is hardly limited.SOLUTION: In a robot, a base end side crank includes a base end side first crank arm connected to a tip portion drive source, a base end side second crank arm disposed side by side with the base end side first crank arm, and a base end side crank pin connecting the base end side first crank arm and the base end side second crank arm. In the robot, a tip side crank includes a tip side first crank arm connected to a tip portion, a tip side second crank arm disposed side by side with the tip side first crank arm, and a tip side crank pin connecting the tip side first crank arm and the tip side second crank arm. In the robot, a first link is connected to the base end side second crank arm and the tip side second crank arm, and a second link is connected to the base end side crank pin and the tip side crank pin.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a robot.

Background Art

[0002] Patent Document 1 describes a parallel link robot capable of reducing the weight of the tip of the arm and the load applied to the base of the arm. Such a parallel link robot includes a robot base, a robot body rotatably connected to the robot base about a first rotation axis, a first robot arm rotatably connected to the robot body about a second rotation axis, a second robot arm rotatably connected to the first robot arm about a third rotation axis, a robot wrist rotatably connected to the second robot arm about a fourth rotation axis, and a drive link connecting the first robot arm and the second robot arm.

[0003] Further, the drive link includes a lower link element rotatably connected to the first robot arm, an upper link element fixed to the second robot arm, and first and second link bars connecting the lower and upper link elements. The lower link element is a crank rotatable about the second rotation axis with respect to the first robot arm, and includes a first link arm, a second link arm, and a connecting portion connecting the first link arm and the second link arm. On the other hand, the upper link element is a crank fixed to the second robot arm, and includes a first link arm, a second link arm, and a connecting portion connecting the first link arm and the second link arm. The first link arms of the lower and upper link elements are connected by the first link bar, and the second link arms of the lower and upper link elements are connected by the second link bar. Therefore, when the lower link element rotates about the second rotation axis, the upper link element rotates about the third rotation axis, and accordingly, the second robot arm rotates about the third rotation axis.

Prior Art Documents

Patent Documents

[0004] "[Patent Document 1]" Japanese Patent Laid-Open No. 3-239483 "[Summary of the Invention]" "[Problems to be Solved by the Invention]"

[0005] In such a parallel link type robot of Patent Document 1, a first link bar that connects the first link arms of the lower and upper link elements is disposed between the first link arm and the second link arm. Therefore, there is a problem that the first link bar contacts a joint portion that connects the first link arm and the second link arm, and the movable range of the parallel link type robot is restricted. "[Means for Solving the Problems]"

[0006] The robot of the present invention includes a base end portion, a central portion connected to the base end portion and rotatable about a first rotation axis with respect to the base end portion, a tip portion connected to the central portion and rotatable about a second rotation axis with respect to the central portion, a tip portion drive source housed in the base end portion for driving the tip portion, and a link mechanism that connects the tip portion drive source and the tip portion, and the link mechanism includes a base end side crank rotatable about the first rotation axis, a tip end side crank connected to the tip portion and rotatable about the second rotation axis together with the tip portion, and a first link and a second link that connect the base end side crank and the tip end side crank, the base end side crank includes a base end side first crank arm connected to the tip portion drive source, a base end side second crank arm disposed side by side with the base end side first crank arm, and a base end side crank pin that connects the base end side first crank arm and the base end side second crank arm at a position displaced from the first rotation axis, The tip-side crank has a tip-side first crank arm connected to the tip portion, a tip-side second crank arm arranged side by side with the tip-side first crank arm, and a tip-side crank pin that connects the tip-side first crank arm and the tip-side second crank arm at a position shifted from the second rotation axis. The first link is located on the side opposite to the base-end side first crank arm and the tip-side first crank arm with respect to the base-end side second crank arm and the tip-side second crank arm, and is connected to the base-end side second crank arm and the tip-side second crank arm. The second link is located between the base-end side first crank arm and the tip-side first crank arm and the base-end side second crank arm and the tip-side second crank arm, and is connected to the base-end side crank pin and the tip-side crank pin.

Brief Description of the Drawings

[0007]

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Embodiments for Carrying Out the Invention

[0008] Hereinafter, the robot of the present invention will be described in detail based on the embodiments shown in the accompanying drawings.

[0009] <First Embodiment> FIG. 1 is a perspective view showing a robot according to the first embodiment. FIG. 2 is a cross-sectional view showing the inside of the second arm. FIG. 3 is a cross-sectional view showing the inside of the base end portion. FIG. 4 is a perspective view showing a link mechanism. FIG. 5 is a plan view showing the link mechanism. FIGS. 6 and 7 are plan views showing the operations of the robot, respectively. FIG. 8 is a plan view showing the robot when the crank angle is 180°.

[0010] In FIG. 1, the vertical direction is the same as the vertical direction, and the upper side in FIG. 1 is also referred to as "upper" and the lower side as "lower". Further, in this specification, "vertical" means not only the case where it coincides with the vertical, but also the case where it is inclined with respect to the vertical within the range where the effects of the present invention can be exhibited. In this specification, "parallel" means not only the case where two objects coincide with each other in parallel, but also the case where they are inclined from parallel within the range where the effects of the present invention can be exhibited.

[0011] The robot 1 shown in FIG. 1 is a horizontal articulated robot, that is, a scalar robot, and is used, for example, in various operations such as holding, transporting, assembling, and inspecting workpieces such as electronic components. However, the use of the robot 1 is not particularly limited.

[0012] The robot 1 includes a base 2 as a base end portion, a robot arm 3 rotatably connected to the base 2, and a control device 10 that controls the driving of each part of the robot 1. The robot arm 3 includes a first arm 31 as a central portion that is connected to the base 2 and rotates around a first rotation axis J1 along the vertical direction with respect to the base 2, and a second arm 32 as a tip portion that is connected to the first arm 31 and rotates around a second rotation axis J2 along the vertical direction with respect to the first arm 31. The first arm 31 is rotatably connected to the base 2 via a speed reducer 412 (see FIG. 3) described later, and the second arm 32 is rotatably connected to the first arm 31 via a shaft 320 extending from the second arm 32 (see FIG. 2).

[0013] Further, a work head 33 is provided at the tip of the second arm 32. As shown in FIG. 2, the work head 33 includes a spline nut 331 and a ball screw nut 332 coaxially arranged at the tip of the second arm 32, and a spline shaft 333 inserted through the spline nut 331 and the ball screw nut 332. The spline shaft 333 is rotatable about a third rotation axis J3, which is the central axis thereof and extends along the vertical direction, with respect to the second arm 32, and is movable (movable up and down) along the third rotation axis J3. Further, a mounting portion 333a for mounting an end effector (not shown) is provided at the lower end of the spline shaft 333. The end effector is detachable from the mounting portion 333a, and an appropriate one suitable for the intended work is selected as appropriate.

[0014] Also, as shown in FIG. 2, the robot 1 includes a spline shaft rotation mechanism 43 that rotates the spline nut 331 to rotate the spline shaft 333 about the third rotation axis J3, and a spline shaft linear motion mechanism 44 that rotates the ball screw nut 332 to move the spline shaft 333 in the direction along the third rotation axis J3.

[0015] The spline shaft rotation mechanism 43 includes an encoder-integrated motor 431 disposed within the second arm 32 and fixed to the second arm 32, and a power transmission mechanism 432 that transmits the rotation of the motor 431 to the spline nut 331. The power transmission mechanism 432 includes a first pulley 432a attached to the output shaft of the motor 431, a second pulley 432b attached to the spline nut 331, and a power transmission belt 432c wound around the first and second pulleys 432a and 432b. With such a configuration, the rotation of the motor 431 is transmitted to the spline nut 331 via the first pulley 432a, the power transmission belt 432c, and the second pulley 432b, and the spline nut 331 rotates.

[0016] The spline shaft linear motion mechanism 44 is disposed within the second arm 32 and includes an encoder-integrated motor 441 fixed to the second arm 32 and a power transmission mechanism 442 that transmits the rotation of the motor 441 to the ball screw nut 332. The power transmission mechanism 442 includes a first pulley 442a attached to the output shaft of the motor 441, a second pulley 442b attached to the ball screw nut 332, and a power transmission belt 442c wound around the first and second pulleys 442a and 442b. With such a configuration, the rotation of the motor 441 is transmitted to the ball screw nut 332 via the first pulley 442a, the power transmission belt 442c, and the second pulley 442b, causing the ball screw nut 332 to rotate.

[0017] However, the configurations of the spline shaft rotation mechanism 43 and the spline shaft linear motion mechanism 44 are not particularly limited.

[0018] Also, as shown in FIG. 3, the robot 1 includes a first arm drive mechanism 41 that rotates the first arm 31 about the first rotation axis J1 with respect to the base 2, and a second arm drive mechanism 42 that rotates the second arm 32 about the second rotation axis J2 with respect to the first arm 31.

[0019] The first arm drive mechanism 41 is disposed within the base 2 and includes an encoder-integrated motor 411 as a central drive source fixed to the base 2, a speed reducer 412 as a central speed reducer that decelerates the rotation of the motor 411 and outputs it to the first arm 31, and a power transmission mechanism 413 that transmits power from the motor 411 to the speed reducer 412. In such a first arm drive mechanism 41, by utilizing the power transmission mechanism 413, the rotation axis of the motor 411 is horizontally displaced with respect to the rotation axis (first rotation axis J1) of the speed reducer 412, forming a space for disposing the second arm drive mechanism 42 directly below the speed reducer 412.

[0020] The power transmission mechanism 413 includes a first pulley 413a attached to the output shaft of the motor 411, a second pulley 413b attached to the speed reducer 412, and a power transmission belt 413c wound around the first and second pulleys 413a and 413b.

[0021] The speed reducer 412 is a hollow speed reducer having a through hole H that penetrates vertically along the first rotating shaft J1. The speed reducer 412 is a harmonic gear device, where the circular spline 412a is fixed to the base 2, the flex spline 412b is fixed to the first arm 31, and the second pulley 413b is fixed to the wave generator 412c. The wave generator 412c is cylindrical with a through hole H formed vertically through it, and a crankshaft 64 (described later) is inserted through the through hole H.

[0022] In such a configuration, the rotation of the motor 411 is transmitted to the wave generator 412c of the speed reducer 412 via the first pulley 413a, the power transmission belt 413c, and the second pulley 413b, causing the wave generator 412c to rotate. Further, the flex spline 412b rotates at a predetermined reduction ratio with respect to the rotation of the wave generator 412c. As a result, the first arm 31 rotates around the first rotating shaft J1 with respect to the base 2.

[0023] Although the first arm drive mechanism 41 has been described above, the configuration of the first arm drive mechanism 41 is not particularly limited. For example, the speed reducer 412 does not have to be a harmonic gear device.

[0024] The second arm drive mechanism 42 is disposed within the base 2. By disposing the second arm drive mechanism 42 within the base 2 in this way, the tip weight of the robot arm 3 can be reduced, and the load applied to the base portion of the robot arm 3 can be decreased. Therefore, the robot 1 has excellent durability and operability.

[0025] The second arm drive mechanism 42 is disposed within the base 2 and includes an encoder-integrated motor 421 as a tip drive source fixed to the base 2, a speed reducer 422 as a tip speed reducer that connects the base 2 and the crankshaft 64 and outputs the rotation of the motor 421 to the crankshaft 64 at a reduced speed, and a power transmission mechanism 423 that transmits power from the motor 421 to the speed reducer 422.

[0026] The power transmission mechanism 423 includes a first pulley 423a attached to the output shaft of the motor 421, a second pulley 423b attached to the speed reducer 422, and a power transmission belt 423c looped around the first and second pulleys 423a, 423b.

[0027] The speed reducer 422 is disposed below the speed reducer 412. That is, the speed reducer 422 is located on the side opposite to the proximal end side crank 6 with respect to the speed reducer 412. Also, the speed reducer 422 is disposed coaxially with the speed reducer 412. The speed reducer 422 is a harmonic gear device, in which a circular spline 422a is fixed to the base 2, a flex spline 422b is fixed to the crankshaft 64, and the second pulley 423b is fixed to a wave generator 422c.

[0028] With such a configuration, the rotation of the motor 421 is transmitted to the wave generator 422c of the speed reducer 422 via the first pulley 423a, the power transmission belt 423c, and the second pulley 423b, and the wave generator 422c rotates. Further, the flex spline 422b rotates at a predetermined reduction ratio with respect to the rotation of the wave generator 422c, and as a result, the crankshaft 64 rotates about the first rotation axis J1 with respect to the base 2.

[0029] Although the second arm drive mechanism 42 has been described above, the configuration of the second arm drive mechanism 42 is not particularly limited. For example, the speed reducer 422 does not have to be a harmonic gear device.

[0030] Further, as shown in FIGS. 4 and 5, the robot 1 further has a link mechanism 5 that transmits the output of the second arm drive mechanism 42 to the second arm 32 and rotates the second arm 32 around the second rotation axis J2 with respect to the first arm 31. Such a link mechanism 5 includes a base end side crank 6 rotatably connected to the base 2 around the first rotation axis J1, a tip end side crank 7 rotatably connected to the first arm 31 around the second rotation axis J2, and a pair of first links 8 and second links 9 that connect the base end side crank 6 and the tip end side crank 7.

[0031] The base end side crank 6 has a pair of crank arms extending horizontally from each other, specifically, a base end side first crank arm 61 and a base end side second crank arm 62 located above the base end side first crank arm 61. The base end side crank 6 also has a base end side crank pin 63. The base end side crank pin 63 is located between the base end side first crank arm 61 and the base end side second crank arm 62 and connects these base end portions to each other. The base end side crank 6 also has a crank shaft 64 extending downward from the tip end portion of the base end side first crank arm 61. The base end side second crank arm 62 has a pin 62a protruding upward from its tip end portion.

[0032] As described above, the crank shaft 64 extends along the first rotation axis J1, passes through the speed reducer 412, and is fixed to the flex spline 422b of the speed reducer 422 at its lower end portion. Therefore, the base end side crank 6 rotates around the first rotation axis J1 with respect to the base 2 by the drive of the second arm drive mechanism 42. By arranging the crank shaft 64 so as to pass through the speed reducer 412 as in this embodiment, the base end side crank 6 can be rotated around the first rotation axis J1 with a simple configuration. Also, the robot 1 can be downsized.

[0033] Further, the tip-side crank 7 has a pair of crank arms extending horizontally from each other, specifically, a tip-side first crank arm 71 and a tip-side second crank arm 72 located above the tip-side first crank arm 71. The tip-side crank 7 also has a tip-side crank pin 73. The tip-side crank pin 73 is located between the tip-side first crank arm 71 and the tip-side second crank arm 72 and connects the base ends of these two arms. The tip-side second crank arm 72 has a pin 72a protruding upward from its tip end.

[0034] In addition, the tip-side first crank arm 71 is connected to the second arm 32. Therefore, the tip-side crank 7, together with the second arm 32, rotates around the second rotation axis J2 with respect to the first arm 31. In particular, in the present embodiment, as shown in FIG. 2, the tip-side first crank arm 71 is integrally formed with the second arm 32. That is, the second arm 32 also serves as the tip-side first crank arm 71. By adopting such a configuration, the size of the robot arm 3 can be reduced. Also, the weight of the tip of the robot arm 3 can be lightened, and the load applied to the base portion of the robot arm 3 can be reduced.

[0035] The first link 8 is rod-shaped and is rotatably connected to the base-side second crank arm 62 of the base-side crank 6 and the tip-side second crank arm 72 of the tip-side crank 7. Specifically, the first link 8 is located above the base-side second crank arm 62 and the tip-side second crank arm 72. The first link 8 is rotatably inserted into a pin 62a protruding from the base-side second crank arm 62 at its base end and rotatably inserted into a pin 72a protruding from the tip-side second crank arm 72 at its tip end.

[0036] On the other hand, the second link 9 is rod-shaped and connects the base-end crank pin 63 of the base-end side crank 6 and the tip-end crank pin 73 of the tip-end side crank 7. Specifically, the second link 9 is positioned between the base-end side first crank arm 61 and the tip-end side first crank arm 71, and between the base-end side second crank arm 62 and the tip-end side second crank arm 72. And the second link 9 is rotatably connected to the base-end crank pin 63 at the base end portion and rotatably connected to the tip-end crank pin 73 at the tip end portion.

[0037] The link mechanism 5 has been described above. According to such a link mechanism 5, as shown in FIG. 6, when the base-end side crank 6 is rotated clockwise by the second arm drive mechanism 42, the rotation of the base-end side crank 6 is transmitted to the tip-end side crank 7 via the first and second links 8 and 9, and the second arm 32 rotates clockwise together with the tip-end side crank 7. Conversely, as shown in FIG. 7, when the base-end side crank 6 is rotated counterclockwise by the second arm drive mechanism 42, the rotation of the base-end side crank 6 is transmitted to the tip-end side crank 7 via the first and second links 8 and 9, and the second arm 32 rotates counterclockwise together with the tip-end side crank 7. In such a robot 1, as described above, the first link 8 connects the base-end side second crank arm 62 and the tip-end side second crank arm 72 from above, and the second link 9 connects the base-end crank pin 63 and the tip-end crank pin 73. Therefore, due to their arrangement, the first link 8 and the second link 9 do not contact the base-end side crank 6 and the tip-end side crank 7, and a wider movable range of the robot 1 can be ensured.

[0038] Here, as shown in FIG. 8, when the crank angles θ1 between the proximal end side first crank arm 61 and the proximal end side second crank arm 62 and the crank angle θ2 between the distal end side first crank arm 71 and the distal end side second crank arm 72 are 0° or 180° in a plan view from the vertical direction, when the first and second arms 31 and 32 are in a straight extended posture, the first and second links 8 and 9 overlap on a line segment L connecting the first and second rotation axes J1 and J2. This state is called a dead point (singular point). From this state, even if the second arm drive mechanism 42 is driven to rotate the second arm 32 clockwise, the second arm 32 may rotate counterclockwise, or conversely, even if the second arm drive mechanism 42 is driven to rotate the second arm 32 counterclockwise, the second arm 32 may rotate clockwise, and the control of the robot 1 tends to become unstable. In particular, in the configuration shown in FIG. 8, a dead point exists in the middle of the movable range of the robot 1, and inevitably, the movement passing through the dead point increases, so that the control of the robot 1 is even more likely to become unstable.

[0039] Therefore, as the crank angles θ1 and θ2, for example, it is preferably 20° or more and 160° or less, and more preferably 45° or more and 135° or less. Thereby, it becomes difficult for a dead point (singular point) of the robot 1 to occur, and even if a dead point occurs, it is possible to avoid the middle of the movable range, so that the control of the robot 1 is stabilized accordingly. Note that the closer the crank angles θ1 and θ2 are to 90°, the larger the torque can be used to rotate the second arm 32, but in a plan view from the vertical direction, the first and second links 8 and 9 are likely to protrude to the side of the first arm 31, which may lead to an increase in the size of the robot 1. Therefore, in the present embodiment, the crank angles θ1 and θ2 are each set to 60°. Thereby, while reducing the size of the robot 1, the second arm 32 can be rotated with sufficiently large torque.

[0040] The control device 10 controls the driving of each part of the robot 1. Such a control device 10 is composed of, for example, a computer, and has a processor (CPU) that processes information, a memory communicably connected to the processor, and an external interface for connecting to an external device. Various programs executable by the processor are stored in the memory, and the processor can read and execute the programs and the like stored in the memory.

[0041] The above described the robot 1. As described above, such a robot 1 includes a base 2 as a base end portion, a first arm 31 as a central portion connected to the base 2 and rotatable about a first rotation axis J1 with respect to the base 2, a second arm 32 as a tip end portion connected to the first arm 31 and rotatable about a second rotation axis J2 with respect to the first arm 31, a motor 421 as a tip end drive source accommodated in the base 2 for driving the second arm 32, and a link mechanism 5 for connecting the motor 421 and the second arm 32. The link mechanism 5 includes a base end side crank 6 rotatable about the first rotation axis J1, a tip end side crank 7 connected to the second arm 32 and rotatable about the second rotation axis J2 together with the second arm 32, and first and second links 8 and 9 for connecting the base end side crank 6 and the tip end side crank 7. The base end side crank 6 includes a base end side first crank arm 61 connected to the motor 421, a base end side second crank arm 62 arranged side by side with the base end side first crank arm 61, and a base end side crank pin 63 connecting the base end side first crank arm 61 and the base end side second crank arm 62 at a position displaced from the first rotation axis J1. The tip end side crank 7 includes a tip end side first crank arm 71 connected to the second arm 32, a tip end side second crank arm 72 arranged side by side with the tip end side first crank arm 71, and a tip end side crank pin 73 connecting the tip end side first crank arm 71 and the tip end side second crank arm at a position displaced from the second rotation axis J2. The first link 8 is located on the opposite side of the base end side first crank arm 61 and the tip end side first crank arm 71 with respect to the base end side second crank arm 62 and the tip end side second crank arm 72, and is connected to the base end side second crank arm 62 and the tip end side second crank arm 72. The second link 9 is located between the base end side first crank arm 61 and the tip end side first crank arm 71 and the base end side second crank arm 62 and the tip end side second crank arm 72, and is connected to the base end side crank pin 63 and the tip end side crank pin 73. According to such a configuration, due to its arrangement, the first link 8 and the second link 9 do not contact the base end side crank 6 and the tip end side crank 7, and a wider movable range of the robot 1 can be ensured.

[0042] Also, as described above, the second arm 32 also serves as the tip-side first crank arm 71. By adopting such a configuration, the size of the robot arm 3 can be reduced. Further, the tip weight of the robot arm 3 can be lightened, and the load applied to the base portion of the robot arm 3 can be reduced.

[0043] Also, as described above, the robot 1 is housed in the base 2, and includes a motor 411 which is a central drive source for driving the first arm 31, a speed reducer 412 which is a central speed reducer that decelerates the input from the motor 411 and transmits it to the first arm 31, and a speed reducer 422 which is a tip-side speed reducer that is located on the side opposite to the base-side crank 6 with respect to the speed reducer 412 and decelerates the input from the motor 421 and transmits it to the base-side crank 6. The base-side crank 6 is disposed so as to penetrate the speed reducer 412, and has a crankshaft 64 that connects the base-side first crank arm 61 and the speed reducer 422. According to such a configuration, the base-side crank 6 can be rotated around the first rotation axis J1 with a simple configuration. Also, the size of the robot 1 can be reduced.

[0044] Also, as described above, in the base-side crank 6, the crank angle θ1 between the base-side first crank arm 61 and the base-side second crank arm 62 is 20° or more and 160° or less, and in the tip-side crank 7, the crank angle θ2 between the tip-side first crank arm 71 and the tip-side second crank arm 72 is 20° or more and 160° or less. According to such a configuration, it is difficult for a dead point (singular point) of the robot 1 to occur, and even if a dead point occurs, the middle of the movable range can be avoided, so that the control of the robot 1 becomes more stable accordingly.

[0045] <Second Embodiment> FIG. 9 is a side view showing a robot according to the second embodiment.

[0046] This embodiment is the same as the first embodiment described above, except that the distal end side first crank arm 71 of the distal end side crank 7 is configured separately from the second arm 32. In the following description, regarding this embodiment, the differences from the above-described embodiments will be mainly described, and the description of the same matters will be omitted. Also, in the drawings of this embodiment, the same reference numerals are given to the same configurations as those in the above-described embodiments.

[0047] As shown in FIG. 9, in the robot 1 of this embodiment, the distal end side first crank arm 71 of the distal end side crank 7 is configured separately from the second arm 32. And the distal end portion of the distal end side first crank arm 71 is fixed to the shaft 320 of the second arm 32.

[0048] Even with such a second embodiment, the same effects as those of the first embodiment described above can be exhibited.

[0049] <Third Embodiment> FIG. 10 is a side view showing a robot according to the third embodiment.

[0050] This embodiment is the same as the second embodiment described above, except that the link mechanism 5 is disposed within the first arm 31. In the following description, regarding this embodiment, the differences from the above-described embodiments will be mainly described, and the description of the same matters will be omitted. Also, in the drawings of this embodiment, the same reference numerals are given to the same configurations as those in the above-described embodiments.

[0051] As shown in FIG. 10, in the robot 1 of this embodiment, the link mechanism 5 is disposed within the first arm 31. According to such a configuration, since the link mechanism 5 that moves complexly is not exposed outside the robot arm 3, the safety of the robot 1 can be enhanced. Also, the link mechanism 5 can be protected from moisture, dust, etc., and the smooth movement of the link mechanism 5 can be maintained for a long period of time.

[0052] Even with such a third embodiment, the same effects as those of the first embodiment described above can be exhibited.

[0053] <Fourth Embodiment> FIG. 11 is a cross-sectional view showing the robot according to the fourth embodiment. FIG. 12 is a plan view of the speed reducer.

[0054] This embodiment is the same as the above-described first embodiment except that the configurations of the speed reducers 412 and 422 are different. In the following description, regarding this embodiment, the differences from the above-described embodiments will be mainly described, and the description of the same matters will be omitted. Also, in each figure of this embodiment, the same components as those in the above-described embodiments are denoted by the same reference numerals.

[0055] As shown in FIG. 11, in the robot 1 of this embodiment, the speed reducer 412 is a roller cam speed reducer. The speed reducer 412 includes a roller gear cam 412f that rotates about a rotation axis J4 along the horizontal direction, and a roller follower 412g that meshes with the roller gear cam 412f and is rotatable about the first rotation axis J1. Further, the roller follower 412g has a through hole H that penetrates vertically, and a base end side crank pin 63 of the base end side crank 6 is inserted into the through hole H. A motor 411 is disposed horizontally beside such a speed reducer 412, and an output shaft of the motor 411 is connected to the roller gear cam 412f. In such a configuration, the roller gear cam 412f rotates by the rotation of the motor 411, and the roller follower 412g rotates at a predetermined reduction ratio with respect to the rotation of the roller gear cam 412f. As a result, the first arm 31 rotates about the first rotation axis J1 with respect to the base 2.

[0056] The speed reducer 422 is also a roller cam speed reducer, similar to the speed reducer 412, and is disposed below the speed reducer 412. The speed reducer 422 has a roller gear cam 422f that rotates around a rotation axis J5 along the horizontal direction, and a roller follower 422g that meshes with the roller gear cam 422f and is rotatable around the first rotation axis J1. Further, at a position displaced from the first rotation axis J1, the lower end of a proximal end side crank pin 63 disposed through the speed reducer 412 is fixed to the roller follower 412g. With such a configuration, the rotation of the motor 421 causes the roller gear cam 422f to rotate, and the roller follower 422g rotates at a predetermined reduction ratio with respect to the rotation of the roller gear cam 422f. As a result, the proximal end side crank 6 rotates around the first rotation axis J1 with respect to the base 2. In such a speed reducer 422, the roller follower 422g can also serve as the proximal end side first crank arm 61, and the weight and size of the link mechanism 5 can be reduced.

[0057] As described above, the robot 1 of the present embodiment is housed in the base 2, and includes a motor 411 for driving the first arm 31, a speed reducer 412 that decelerates the input from the motor 411 and transmits it to the first arm 31, and a speed reducer 422 that is located on the side opposite to the proximal end side crank 6 with respect to the speed reducer 412 and decelerates the input from the motor 421 and transmits it to the proximal end side crank 6. The speed reducer 422 also serves as the proximal end side first crank arm 61, and the proximal end side crank pin 63 passes through the speed reducer 412 and is connected to the speed reducer 422. According to such a configuration, the weight and size of the link mechanism 5 can be reduced.

[0058] Also, according to the fourth embodiment, the same effects as those of the first embodiment described above can be achieved.

[0059] <Fifth Embodiment> FIG. 13 is a plan view showing a robot according to the fifth embodiment. FIG. 14 is a cross-sectional view showing the first link. FIG. 15 is a cross-sectional view showing a state where the first link is extended. FIG. 16 is a cross-sectional view showing a state where the first link is contracted.

[0060] This embodiment is the same as the above-described first embodiment except that the configuration of the link mechanism 5 is different. In the following description, regarding this embodiment, the differences from the above-described embodiments will be mainly described, and the description of the same matters will be omitted. Also, in each figure of this embodiment, the same reference numerals are given to the same configurations as those in the above-described embodiments.

[0061] As shown in FIG. 13, in the robot 1 of this embodiment, the first link 8 and the second link 9 each have a length adjustment mechanism 80, 90 and can change their lengths. For example, by making the first link 8 relatively longer than the second link 9, or conversely, making the first link 8 relatively shorter than the second link 9, or by making both the first and second links 8, 9 longer, or conversely, making both the first and second links 8, 9 shorter, a compressive force or a tensile force can be applied to the first and second links 8, 9, and tension can be applied to the connecting portions of each part constituting the link mechanism 5, that is, the connecting portions of the base-end side crank 6 with the first and second links 8, 9 and the connecting portions of the tip-end side crank 7 with the first and second links 8, 9, respectively. Thereby, the rattling of the link mechanism 5 can be reduced. Therefore, the second arm 32 can be rotated more accurately.

[0062] Next, the first and second links 8, 9 will be described. Since they have the same configuration, in the following, the first link 8 will be described as a representative, and the description of the second link 9 will be omitted.

[0063] As shown in FIG. 14, the first link 8 is configured such that a single rod is diagonally cut at its central portion, and includes a proximal-side link 81 positioned on the proximal end side and a distal-side link 82 positioned on the distal end side. The proximal-side link 81 is rotatably connected to the proximal-side second crank arm 62 of the proximal-side crank 6 at the proximal end portion, and has an inclined surface 81a whose distal end surface is inclined with respect to the normal of the central axis. On the other hand, the distal-side link 82 is rotatably connected to the distal-side second crank arm 72 of the distal-side crank 7 at the distal end portion, and has an inclined surface 82a whose proximal end surface is inclined with respect to the normal. The proximal-side link 81 and the distal-side link 82 are arranged with the inclined surfaces 81a and 82a in contact with each other.

[0064] Furthermore, the first link 8 includes a bolt B1 passing through the proximal-side link 81 and the distal-side link 82, and a nut N1 fastened to the bolt B1. In such a configuration, as shown in FIG. 15, by tightening the nut N1, the distal-side link 82 moves toward the distal end along the inclined surface 81a, and the first link 8 extends. Conversely, as shown in FIG. 16, by loosening the nut N1, the distal-side link 82 moves toward the proximal end along the inclined surface 81a, and the first link 8 contracts. According to such a configuration, the configuration of the length adjustment mechanism 80 becomes simple.

[0065] As described above, in the robot 1 of the present embodiment, at least one of the first link 8 and the second link 9 has a length adjustment mechanism 80, 90. According to such a configuration, by adjusting the lengths of the first and second links 8 and 9, tension can be applied to the connecting portions of each part constituting the link mechanism 5, that is, the connecting portions of the proximal-side crank 6 with the first and second links 8 and 9 and the connecting portions of the distal-side crank 7 with the first and second links 8 and 9, respectively, and rattling of the link mechanism 5 can be reduced. Therefore, the second arm 32 can be rotated more accurately.

[0066] Even with such a fifth embodiment, the same effects as those of the first embodiment described above can be achieved. In this embodiment, both the first and second links 8 and 9 are configured to be able to adjust their lengths. However, the present invention is not limited to this, and only one of the first and second links 8 and 9 may be configured to be able to adjust its length. Even in this case, the same effects as those of the present embodiment can be achieved.

[0067] <Sixth Embodiment> FIG. 17 is a cross-sectional view showing a first link included in the robot according to the sixth embodiment. FIG. 18 is a cross-sectional view showing a state where the first link is extended. FIG. 19 is a cross-sectional view showing a state where the first link is contracted.

[0068] This embodiment is the same as the fifth embodiment described above, except that the configurations of the first and second links 8 and 9 are different. In the following description, regarding this embodiment, the differences from the above-described embodiments will be mainly described, and the description of the same matters will be omitted. Also, in each figure of this embodiment, the same components as those of the above-described embodiments are denoted by the same reference numerals. Further, since the first and second links 8 and 9 have the same configuration, the first link 8 will be described as a representative below, and the description of the second link 9 will be omitted.

[0069] As shown in FIG. 17, the first link 8 of this embodiment has a rod-shaped screw member 830 and a pair of nuts N21 and N22 screwed onto the screw member 830. The nuts N21 and N22 move toward the distal end side or the proximal end side by rotating with respect to the screw member 830. The first link 8 also has a cylindrical proximal end side link 831 located on the proximal end side of the nut N21 and inserted through the screw member 830, and a cylindrical distal end side link 832 located on the distal end side of the nut N22 and inserted through the screw member 830. The proximal end side link 831 is fixed to the nut N21 at its distal end portion and is connected to the proximal end side second crank arm 62 of the proximal end side crank 6 at its proximal end portion. On the other hand, the distal end side link 832 is fixed to the nut N22 at its proximal end portion and is connected to the distal end side second crank arm 72 of the distal end side crank 7 at its distal end portion.

[0070] In such a configuration, as shown in FIG. 18, by rotating at least one of the nuts N21 and N22 so that the distance between the nuts N21 and N22 increases, the first link 8 extends. Conversely, as shown in FIG. 19, by rotating at least one of the nuts N21 and N22 so that the distance between the nuts N21 and N22 decreases, the first link 8 contracts. According to the above configuration, the length of the first link 8 can be adjusted with a simple configuration. According to such a configuration, the configuration of the length adjustment mechanism 80 becomes simple.

[0071] Also, such a sixth embodiment can exhibit the same effects as those of the first embodiment described above. In this embodiment, both the first and second links 8 and 9 are configured to be able to adjust their lengths, but the present invention is not limited to this, and only one of the first and second links 8 and 9 may be configured to be able to adjust its length. Even in this case, the same effects as those of this embodiment can be exhibited.

[0072] <Seventh Embodiment> FIG. 20 is a plan view showing a first link provided in the robot according to the seventh embodiment. FIG. 21 is a plan view showing a state where the first link is extended. FIG. 22 is a plan view showing a state where the first link is contracted.

[0073] This embodiment is the same as the fifth embodiment described above, except that the configurations of the first and second links 8 and 9 are different. In the following description, regarding this embodiment, the differences from the above-described embodiments will be mainly described, and the description of the same matters will be omitted. Also, in each drawing of this embodiment, the same reference numerals are given to the same configurations as those of the above-described embodiments. Also, since the first and second links 8 and 9 have the same configuration as each other, in the following, the first link 8 will be described representatively, and the description of the second link 9 will be omitted.

[0074] As shown in FIG. 20, the first link 8 of the present embodiment includes a tip-side link 842, a screw member 840 extending from the tip-side link 842 toward the base end, a base-end side link 841 inserted through the screw member 840, and a nut N3 screwed onto the screw member 840 so as to sandwich the base-end side link 841 between the tip-side link 842. Further, the tip-side link 842 is connected to the tip-side second crank arm 72 of the tip-side crank 7 at its tip, and serrated unevenness 842a formed along the circumferential direction is formed on the base end surface. Further, the base-end side link 841 is connected to the base-end side second crank arm 62 of the base-end side crank 6 at its base end, and serrated unevenness 841a that meshes with the unevenness 842a is formed on the tip end surface. In such a configuration, as shown in FIG. 21, by rotating the nut N3 and moving it toward the base end, the meshing depth of the unevenness 841a and 842a becomes shallower, and the first link 8 extends. Conversely, as shown in FIG. 22, by rotating the nut N3 and moving it toward the tip end, the meshing depth of the unevenness 841a and 842a becomes deeper, and the first link 8 contracts. According to such a configuration, the configuration of the length adjustment mechanism 80 becomes simple.

[0075] Even with such a seventh embodiment, the same effects as those of the first embodiment described above can be exhibited. In the present embodiment, both the first and second links 8 and 9 are configured to be able to adjust their lengths, but the present invention is not limited to this, and only one of the first and second links 8 and 9 may be configured to be able to adjust its length. Even in this case, the same effects as those of the present embodiment can be exhibited.

[0076] <Eighth Embodiment> FIG. 23 is a side view of the robot according to the eighth embodiment. FIG. 24 is a cross-sectional view showing the base-end side crank provided in the robot.

[0077] This embodiment is the same as the first embodiment described above, except that the configurations of the base-end side crank 6 and the tip-end side crank 7 are different. In the following description, regarding this embodiment, the differences from the above-described embodiments will be mainly described, and the description of the same matters will be omitted. Also, in each figure of this embodiment, the same reference numerals are given to the same configurations as those in the above-described embodiments.

[0078] In the fifth to seventh embodiments described above, the first and second links 8 and 9 are provided with the length adjustment mechanisms 80 and 90 in order to suppress the rattling of the link mechanism 5. On the other hand, in this embodiment, the rattling of the link mechanism 5 is suppressed by configuring the base-end side crank 6 and the tip-end side crank 7 so that the crank angles θ1 and θ2 can be adjusted. That is, in the robot 1 of this embodiment, as shown in FIG. 23, the base-end side crank 6 has the crank angle adjustment mechanism 630, and the tip-end side crank 7 has the crank angle adjustment mechanism 730. Hereinafter, the configurations of the base-end side crank 6 and the tip-end side crank 7 will be described. Since these have the same configuration as each other, hereinafter, the base-end side crank 6 will be described representatively, and the description of the tip-end side crank 7 will be omitted.

[0079] As shown in FIG. 24, the proximal end side crank pin 63 has the same configuration as the first and second links 8 and 9 of the sixth embodiment described above. That is, the proximal end side crank pin 63 includes, as a crank angle adjustment mechanism 630, a rod-shaped screw member 640 extending vertically, and a pair of nuts N41 and N42 screwed onto the screw member 640. The nuts N41 and N42 move up and down by rotating with respect to the screw member 640. Further, the proximal end side crank pin 63 is located below the nut N41 and has a lower pin 641 inserted through the screw member 640, and is located above the nut N42 and has an upper pin 642 inserted through the screw member 640. Further, the lower pin 641 is fixed to the proximal end side first crank arm 61 at its lower end and is fixed to the nut N41 at its upper end. Similarly, the upper pin 642 is fixed to the proximal end side second crank arm 62 at its upper end and is fixed to the nut N42 at its lower end. With such a configuration, the crank angle θ1 can be adjusted by rotating at least one of the nuts N41 and N42. By adjusting the crank angle θ1, a compressive force or a tensile force is applied to the first and second links 8 and 9, and tension can be applied to the connecting portions of each part constituting the link mechanism 5, that is, the connecting portions between the proximal end side crank 6 and the first and second links 8 and 9 and the connecting portions between the distal end side crank 7 and the first and second links 8 and 9, respectively. Thereby, the rattling of the link mechanism 5 can be reduced. Therefore, the second arm 32 can be rotated more accurately.

[0080] As described above, in the robot 1 of the present embodiment, the base-end side crank 6 has a crank angle adjustment mechanism 630 for adjusting the crank angle θ1 between the base-end side first crank arm 61 and the base-end side second crank arm 62. Further, in the robot 1 of the present embodiment, the tip-side crank 7 has a crank angle adjustment mechanism 730 for adjusting the crank angle θ2 between the tip-side first crank arm 71 and the tip-side second crank arm 72. According to such a configuration, tension can be applied to the connecting portions of each part constituting the link mechanism 5, that is, the connecting portions between the base-end side crank 6 and the first and second links 8 and 9 and the connecting portions between the tip-side crank 7 and the first and second links 8 and 9, respectively. Therefore, the rattling of the link mechanism 5 can be reduced thereby.

[0081] Also, such a eighth embodiment can exhibit the same effects as those of the first embodiment described above. In the present embodiment, both the base-end side crank 6 and the tip-side crank 7 are configured to be able to adjust the crank angle, but the present invention is not limited to this, and only one of the base-end side crank 6 and the tip-side crank 7 may be configured to be able to adjust the crank angle. Even in this case, the same effects as those of the present embodiment can be exhibited.

[0082] <Ninth Embodiment> FIG. 25 is a side view showing the base-end side crank included in the robot according to the ninth embodiment.

[0083] This embodiment is the same as the eighth embodiment described above except that the configurations of the base-end side crank 6 and the tip-side crank 7 are different. In the following description, regarding this embodiment, the description will focus on the differences from the above-described embodiments, and the description of the same matters will be omitted. Also, in the drawings of the present embodiment, the same reference numerals are given to the same configurations as those of the above-described embodiments. Further, since the base-end side crank 6 and the tip-side crank 7 have the same configuration as each other, in the following, the base-end side crank 6 will be described representatively, and the description of the tip-side crank 7 will be omitted.

[0084] As shown in Fig. 25, the base-end side crank pin 63 of the base-end side crank 6 has the same configuration as the first and second links 8 and 9 of the seventh embodiment described above. That is, the base-end side crank pin 63, as a crank angle adjustment mechanism 630, includes a lower pin 651 whose lower end is fixed to the base-end side first crank arm 61, a screw member 650 extending upward from the lower pin 651, an upper pin 652 inserted through the screw member 650 and whose upper end is fixed to the base-end side second crank arm 62, and a nut N5 screwed onto the screw member 650 so as to sandwich the upper pin 652 between the lower pin 651. Further, on the upper end surface of the lower pin 651, serrated irregularities 651a formed along the circumferential direction are formed, and on the lower end surface of the upper pin 652, serrated irregularities 652a that mesh with the irregularities 651a are formed. With such a configuration, by rotating the nut N5 to rotate the upper pin 652 relative to the lower pin 651, the meshing depth of the irregularities 651a and 652a can be adjusted, thereby adjusting the crank angle θ1.

[0085] Also, the ninth embodiment can achieve the same effects as the first embodiment described above. In this embodiment, both the base-end side crank 6 and the tip-end side crank 7 are configured to be able to adjust the crank angle, but it is not limited to this, and only one of the base-end side crank 6 and the tip-end side crank 7 may be configured to be able to adjust the crank angle. Even in this case, the same effects as this embodiment can be achieved.

[0086] <Tenth Embodiment> Fig. 26 is a side view showing the robot according to the tenth embodiment.

[0087] This embodiment is the same as the first embodiment described above, except that the robot 1 is a vertical articulated robot. In the following description, regarding this embodiment, the differences from the above-described embodiments will be mainly described, and the description of the same matters will be omitted. Also, in the drawings of this embodiment, the same components as those in the above-described embodiments are denoted by the same reference numerals.

[0088] As shown in FIG. 26, the robot arm 3 of the robot 1 according to the present embodiment has a configuration in which six arms 341, 342, 343, 344, 345, and 346 are rotatably connected in this order from the base 2 side. In the robot 1 having such a configuration, the arm 341 is the "base end portion", the arm 342 is the "central portion", and the arm 343 is the "tip end portion". The arm 342 rotates around the rotation axis JJ2 with respect to the arm 341, and the arm 343 rotates around the rotation axis JJ3 with respect to the arm 342. The rotation axes JJ2 and JJ3 are parallel to each other.

[0089] Further, the robot 1 has a drive mechanism 45 that rotates the arm 343 around the rotation axis JJ3 with respect to the arm 342. The drive mechanism 45 has a motor 451 with a built-in encoder as a tip drive source fixed to the arm 341.

[0090] Further, the robot 1 has a link mechanism 5 that transmits the output of the drive mechanism 45 to the arm 343 and rotates the arm 343 around the rotation axis JJ3 with respect to the arm 342. Such a link mechanism 5 includes a base end side crank 6 rotatably connected to the arm 341 around the rotation axis JJ2, a tip end side crank 7 rotatably connected to the arm 342 around the rotation axis JJ3 and connected to the arm 343, and a pair of first links 8 and second links 9 that connect the base end side crank 6 and the tip end side crank 7. Since the configuration of the link mechanism 5 is the same as that of the above-described embodiment, the description thereof is omitted.

[0091] Also, the tenth embodiment can exhibit the same effects as those of the first embodiment described above.

[0092] As described above, the robot of the present invention has been described based on the illustrated embodiments. However, the present invention is not limited thereto, and the configuration of each part can be replaced with any configuration having the same function. Further, any other arbitrary components may be added to the present invention. Also, the above-described embodiments may be appropriately combined.

Explanation of Reference Numerals

[0093] 1… Robot, 10… Control device, 2… Base, 3… Robot arm, 31… First arm, 32… Second arm, 320… Shaft, 33… Working head, 331… Spline nut, 332… Ball screw nut, 333… Spline shaft, 333a… Mounting part, 341… Arm, 342… Arm, 343… Arm, 344… Arm, 345… Arm, 346… Arm, 41… First arm drive mechanism, 411… Motor, 412… Reducer, 412a… Circular spline, 412b… Flex spline, 412c… Wave generator, 412f… Roller gear cam, 412g… Roller follower, 413… Power transmission mechanism, 413a… First pulley, 413b… Second pulley, 413c… Power transmission belt, 42… Second arm drive mechanism, 421… Motor, 422… Reducer, 422a… Circular spline, 422b… Flex spline, 422c… Wave generator, 422f… Roller gear cam, 422g… Roller follower, 423… Power transmission mechanism, 423a… First pulley, 423b… Second pulley, 423c… Power transmission belt, 43… Spline shaft rotation mechanism, 431… Motor, 432… Power transmission mechanism, 432a… First pulley, 432b… Second pulley, 432c… Power transmission belt, 44… Spline shaft linear motion mechanism, 441… Motor, 442… Power transmission mechanism, 442a… First pulley, 442b… Second pulley, 442c… Power transmission belt, 45… Drive mechanism, 451… Motor, 5… Link mechanism, 6… Base end side crank, 61… Base end side first crank arm, 62… Base end side second crank arm, 62a… Pin, 63… Base end side crank pin, 630… Crank angle adjustment mechanism, 64… Crank shaft, 640… Screw member, 641… Lower pin, 642… Upper pin, 650… Screw member, 651… Lower pin, 651a… Concave and convex, 652… Upper pin, 652a… Concave and convex, 7… Tip end side crank, 71… Tip end side first crank arm, 72… Tip end side second crank arm, 72a… Pin, 73… Tip end side crank pin, 730… Crank angle adjustment mechanism, 8… First link, 80… Length adjustment mechanism, 81… Base end side link, 81a… Inclined surface, 82… Tip end side link, 82a… Inclined surface, 830… Screw member, 831… Base end side link, 832… Tip end side link, 840… Screw member, 841… Base end side link, 841a… Concave and convex, 842… Tip end side link,842a…concavity and convexity, 9…second link, 90…length adjustment mechanism, B1…bolt, H…through hole, J1…first rotating shaft, J2…second rotating shaft, J3…third rotating shaft, J4…rotating shaft, J5…rotating shaft, JJ2…rotating shaft, JJ3…rotating shaft, L…line segment, N1…nut, N21…nut, N22…nut, N3…nut, N41…nut, N42…nut, N5…nut, θ1…crank angle, θ2…crank angle

Claims

1. A base end portion, A central portion connected to the base end portion and rotatable about a first rotation axis with respect to the base end portion, A tip portion connected to the central portion and rotatable about a second rotation axis with respect to the central portion, A tip drive source housed in the base end portion for driving the tip portion, And a link mechanism connecting the tip drive source and the tip portion, The link mechanism includes a base end side crank rotatable about the first rotation axis, a tip end side crank connected to the tip portion and rotatable about the second rotation axis together with the tip portion, and a first link and a second link connecting the base end side crank and the tip end side crank, The base end side crank includes a base end side first crank arm connected to the tip drive source, a base end side second crank arm arranged side by side with the base end side first crank arm, and a base end side crank pin connecting the base end side first crank arm and the base end side second crank arm at a position displaced from the first rotation axis, The tip end side crank includes a tip end side first crank arm connected to the tip portion, a tip end side second crank arm arranged side by side with the tip end side first crank arm, and a tip end side crank pin connecting the tip end side first crank arm and the tip end side second crank arm at a position displaced from the second rotation axis, The first link is located on the opposite side of the base end side first crank arm and the tip end side first crank arm with respect to the base end side second crank arm and the tip end side second crank arm, and is connected to the base end side second crank arm and the tip end side second crank arm, The second link is located between the base end side first crank arm and the tip end side first crank arm and the base end side second crank arm and the tip end side second crank arm, and is connected to the base end side crank pin and the tip end side crank pin. A robot characterized by this.

2. The robot according to claim 1, wherein the tip portion also serves as the tip-side first crank arm.

3. The robot according to claim 1, wherein the link mechanism is disposed within the central portion.

4. A central portion drive source housed in the base end portion for driving the central portion, A central portion speed reducer that decelerates the input from the central portion drive source and transmits it to the central portion, A tip portion speed reducer that is located on the side opposite to the base end side crank with respect to the central portion speed reducer and decelerates the input from the tip portion drive source and transmits it to the base end side crank, and The robot according to claim 1, wherein the base end side crank is disposed so as to penetrate the central portion speed reducer and has a crank shaft that connects the base end side first crank arm and the tip portion speed reducer.

5. A central portion drive source housed in the base end portion for driving the central portion, A central portion speed reducer that decelerates the input from the central portion drive source and transmits it to the central portion, A tip portion speed reducer that is located on the side opposite to the base end side crank with respect to the central portion speed reducer and decelerates the input from the tip portion drive source and transmits it to the base end side crank, and The robot according to claim 1, wherein the tip portion speed reducer also serves as the base end side first crank arm, and the base end side crank pin penetrates the central portion speed reducer and is connected to the tip portion speed reducer.

6. The robot according to claim 1, wherein at least one of the first link and the second link has a length adjustment mechanism.

7. In the base end side crank, the crank angle between the base end side first crank arm and the base end side second crank arm is 20° or more and 160° or less, The robot according to claim 1, wherein in the tip side crank, the crank angle between the tip side first crank arm and the tip side second crank arm is 20° or more and 160° or less.

8. The robot according to claim 1, wherein the base-end side crank has a crank angle adjustment mechanism for adjusting the crank angles of the base-end side first crank arm and the base-end side second crank arm.

9. The robot according to claim 1, wherein the tip-end side crank has a crank angle adjustment mechanism for adjusting the crank angles of the tip-end side first crank arm and the tip-end side second crank arm.

Images