Robot wrist

Abstract

A robot wrist 4 comprises a first base 41, a second base 42, a link mechanism 6, and a first actuator 51. The link mechanism 6 includes a Chebyshev linkage mechanism 60 that links the second base 42 to the first base 41 so as to allow linear movement in a linear advancement direction Z. The Chebyshev linkage mechanism 60 includes a rotationally-driven driver 61 that is linked to the first base 41 so as to be capable of rotating around a drive shaft D, a follower 62 that is linked to the first base 41 so as to be capable of rotating around an axis that is parallel to the drive shaft D, and a coupler 63 that is linked to each of the driver 61 and the follower 62 so as to be capable of rotating around an axis that is parallel to the drive shaft D. The second base 42 is linked to the coupler 63.

Description

Robot List

[0001] The technology disclosed herein relates to robotics.

[0002] Conventionally, robot arms with connected hands have been known. For example, in the robot arm described in Patent Document 1, the hand is moved linearly from a stopped state of the robot arm. This allows the hand to access a workpiece or the like simply by moving the hand, without moving the robot arm.

[0003] JP 2009-255207 A

[0004] The reach of the hand increases with the linear stroke of the hand. Therefore, it is conceivable to configure the robot wrist, which connects the robot arm and hand, so that the hand can move linearly. However, increasing the linear stroke of the hand may result in an increase in the size of the robot wrist.

[0005] The technology of the present disclosure has been made in consideration of the above points, and its purpose is to provide a compact robot wrist with a large stroke in the linear direction.

[0006] The robot wrist of the present disclosure comprises a first base attached to a robot arm, a second base to which a hand is attached, a link mechanism that movably connects the second base to the first base, and a first actuator that drives the link mechanism, wherein the link mechanism includes a Chebyshev link mechanism that connects the second base to the first base so as to be linearly movably in a predetermined rectilinear direction, and the Chebyshev link mechanism has a driver that is rotatably connected to the first base about a predetermined drive axis and is driven to rotate, a follower that is rotatably connected to the first base about an axis parallel to the drive axis, and intermediate links that are rotatably connected to each of the driver and follower about an axis parallel to the drive axis, and the second base is connected to the intermediate link.

[0007] According to the robot wrist, it is possible to provide a robot wrist that is compact and has a large stroke in the linear direction.

[0008] FIG. 1 is a schematic diagram showing a robot. FIG. 2 is a schematic diagram illustrating the movement of the wrist and hand within a container during transfer operations. FIG. 3 is a perspective view of the wrist in a basic state. FIG. 4 is a side view of the wrist in a basic state. FIG. 5 is a plan view of the wrist in a basic state. FIG. 6 is a cross-sectional view of the wrist taken along line VI-VI in FIG. 5. FIG. 7 is a side view of the wrist in an advanced state. FIG. 8 is a side view of the wrist when the hand is most advanced in the straight-line direction. FIG. 9 is a perspective view of the wrist when the hand is most advanced in the straight-line direction. FIG. 10 is a side view of the wrist after a pitch motion. FIG. 11 is a side view of the wrist 4 when the hand is most advanced in the straight-line direction and the pitch angle is 90 degrees. FIG. 12 is a perspective view of the wrist after a roll motion. FIG. 13 is a front view of the wrist when the link mechanism has rotated around the roll axis. FIG. 14 is a side view of the wrist after a yaw motion. FIG. 15 is a front view of the hand and wrist positioned above a container. Fig. 16 is a front view of the hand and wrist after a roll motion. Fig. 17 is a front view of the hand and wrist after a rectilinear motion. Fig. 18 is a side view of the hand and wrist before a yaw motion when picking multiple adjacent workpieces. Fig. 19 is a side view of the hand and wrist after a yaw motion when picking multiple adjacent workpieces. Fig. 20 is a side view of the hand and wrist with the hand holding a workpiece retreated in the rectilinear direction. Fig. 21 is a side view of the hand and wrist with the hand holding a workpiece rotated around the pitch axis.

[0009] Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings. In this disclosure, "parallel," "orthogonal," or "identical" not only means "strictly parallel," "orthogonal," or "identical," but also "substantially parallel," "orthogonal," or "identical."

[0010] 1 is a schematic diagram showing a robot 1. The robot 1 performs a transfer operation. Specifically, the robot 1 takes out a workpiece W from a first container C1 placed on a shelf S and transfers the workpiece W to a second container C2. The first container C1 is a source container that accommodates the workpiece W. The second container C2 is a destination container that accommodates the workpiece W.

[0011] The shelf S has a plurality of shelf boards s1 arranged at intervals in the vertical direction. The first container C1 is placed on the shelf boards s1. On the shelf S, a work space H is present between the first container C1 and the shelf board s1 located above the first container C1, allowing the robot arm 2 to enter.

[0012] The robot 1 includes a cart 11, an elevator 12 placed on the cart 11, a robot arm 2 attached to the elevator 12, a robot wrist 4 attached to the tip of the robot arm 2, and a hand 3 attached to the robot wrist 4. Hereinafter, the robot wrist 4 will also be simply referred to as "wrist 4."

[0013] The robot 1 moves by traveling on a carriage 11. The carriage 11 is, for example, an automated guided vehicle (AGV). In this example, the carriage 11 carries a second container C2.

[0014] The elevator 12 raises, lowers, and rotates the robot arm 2. In this example, the elevator 12 has a support column 12a. The support column 12a has an axis extending in the vertical direction. The axis of the support column 12a is also referred to as the lifting axis U. The support column 12a is attached to the carriage 11 so as to be rotatable about the lifting axis U. The support column 12a supports the robot arm 2 so as to be movable along the lifting axis U. The elevator 12 has a linear actuator that moves the robot arm 2 along the lifting axis U, and a rotary actuator that rotates the support column 12a about the lifting axis U. In other words, the elevator 12 moves the robot arm 2 along the lifting axis U using the linear actuator. The elevator 12 rotates the support column 12a, and therefore the robot arm 2, about the lifting axis U using the rotary actuator.

[0015] The robot arm 2 is a linear-acting telescopic arm. The robot arm 2 extends and retracts in the direction of a predetermined advance / retract axis V. By extending and retracting, the robot arm 2 moves the wrist 4 and the hand 3. Specifically, the robot arm 2 has multiple cylindrical arm housings 21. The axis of each arm housing 21 coincides with the advance / retract axis V. The multiple arm housings 21 are nested. The multiple arm housings 21 are movable relative to one another in the direction of the advance / retract axis V. The robot arm 2 has a linear actuator that moves the multiple arm housings 21 relative to one another. By the multiple arm housings 21 moving relatively in the direction of the advance / retract axis V, the robot arm 2 extends and retracts in the direction of the advance / retract axis V.

[0016] The robot arm 2 is supported by the elevator 12 with the advance / retract axis V intersecting the lift axis U. Specifically, the advance / retract axis V is perpendicular to the lift axis U. The advance / retract axis V may be disposed at a skewed position relative to the lift axis U.

[0017] The wrist 4 moves the hand 3 relative to the robot arm 2. The wrist 4 is attached to the tip of the robot arm 2.

[0018] The hand 3 holds the workpiece W. The hand 3 may hold the workpiece W in any manner. For example, the hand 3 may hold the workpiece W by gripping or suction. In this example, the hand 3 grips the workpiece W. The hand 3 has a hand body 31 and a plurality of fingers 32 attached to the hand body 31. The hand 3 opens and closes the plurality of fingers 32.

[0019] A transfer operation by the robot 1 will now be briefly described. Fig. 2 is a schematic diagram illustrating the movement of the wrist 4 and hand 3 within a container during the transfer operation. As shown in Fig. 1, the robot 1 moves to a position facing the shelf S by traveling on the cart 11. At this time, the elevator 12 moves the robot arm 2 so that the hand 3 is positioned at a predetermined entry start position. The entry start position is a position where the hand 3 faces the working space H between the target first container C1 and the shelf s1 located above it.

[0020] Next, the robot 1 extends the robot arm 2, causing the robot arm 2 to enter the workspace H. This causes the wrist 4 and the hand 3 to enter the workspace H. The hand 3 is moved to a position above the workpiece W to be picked in the first container C1.

[0021] 2, the robot 1 moves the hand 3 into the first container C1. For example, the robot 1 moves the hand 3 via the wrist 4 in a direction intersecting with the advance / retract axis V of the robot arm 2, and causes the hand 3 to enter the first container C1. Then, the robot 1 grips the workpiece W to be picked with the fingers 32 of the hand 3.

[0022] Once the gripping is complete, the robot 1 moves the hand 3 above the first container C1, i.e., to the workspace H. From this state, the robot 1 retracts the robot arm 2 and retracts the hand 3 together with the workpiece W from the workspace H.

[0023] Thereafter, the elevator 12 rotates and raises and lowers the robot arm 2 to move the hand 3 above the second container C2. The robot 1 moves the hand 3 into the second container C2. The robot 1 places the workpiece W into the second container C2 by releasing the grip of the workpiece W by the fingers 32 of the hand 3.

[0024] In this way, the workpiece W to be picked is transferred from the first container C1 to the second container C2.

[0025] =Wrist= Next, the wrist 4 will be described in detail. Fig. 3 is a perspective view of the wrist 4 in the basic state. Fig. 4 is a side view of the wrist 4 in the basic state. Fig. 5 is a plan view of the wrist 4 in the basic state. Note that the hand 3 is omitted from Figs. 3 and 5.

[0026] The wrist 4 linearly moves the hand 3 in a predetermined rectilinear direction Z. The wrist 4 includes a first base 41 attached to the robot arm 2, a second base 42 to which the hand 3 is attached, a link mechanism 6 that movably connects the second base 42 to the first base 41, and a first actuator 51 that drives the link mechanism 6. The wrist 4 is attached to the robot arm 2 via the first base 41. The hand 3 is attached to the wrist 4 via the second base 42. The first base 41 and the second base 42 are connected to each other via the link mechanism 6. The first actuator 51 drives the link mechanism 6, thereby moving the second base 42 relative to the first base 41. In other words, the hand 3 moves relative to the robot arm 2.

[0027] The link mechanism 6 includes a Chebyshev link mechanism 60 that connects the second base 42 to the first base 41 so as to be linearly movable in a predetermined translatory direction Z. The first actuator 51 drives a link included in the Chebyshev link mechanism 60 to linearly move the second base 42, i.e., the hand 3, in the translatory direction Z.

[0028] Here, the linear movement of the second base 42 by the Chebyshev link mechanism 60 is not limited to strictly linear movement, and may be substantially linear movement. In this example, the linear movement of the second base 42 is substantially linear movement along the linear direction Z. The linear direction Z is a direction intersecting the advance / retraction axis V of the robot arm 2, and more specifically, a direction perpendicular to the advance / retraction axis V. In other words, the wrist 4 linearly moves the hand 3 via the link mechanism 6 in a direction intersecting the advance / retraction direction of the robot arm 2.

[0029] Furthermore, the wrist 4 performs pitch, roll, and yaw movements in addition to linear movement. Specifically, the wrist 4 further includes a second actuator 52 that rotates the second base 42 about a pitch axis P extending in a direction intersecting the linear direction Z, and a pitch transmission mechanism 8 that transmits the driving force of the second actuator to the second base 42. The wrist 4 further includes a third actuator 53 that rotates the second base 42 about a roll axis R extending in a direction intersecting both the direction of the pitch axis P and the linear direction Z. The wrist 4 further includes a fourth actuator 54 that rotates the hand 3 about a predetermined yaw axis Y, and a yaw transmission mechanism 79 that transmits the driving force of the fourth actuator 54. The basic state of the wrist 4 is a reference state for linear movement, pitch movement, roll movement, and yaw movement.

[0030] =First Base= The first base 41 has a base body 43 attached to the robot arm 2, and a rotating body 44 rotatably connected to the base body 43. The base body 43 is fixed to the tip of the robot arm 2 (in this example, the end opposite the elevator 12). The rotating body 44 is connected to the base body 43 via a bearing so as to be rotatable around a roll axis R. In this example, the roll axis R is parallel to the advance / retract axis V, and more specifically, is aligned in a straight line with the advance / retract axis V. A link mechanism 6 is attached to the rotating body 44.

[0031] = Second Base = The second base 42 has a base body 45 attached to the link mechanism 6, and a rotating body 46 rotatably connected to the base body 45. The rotating body 46 is connected to the base body 45 via a bearing so as to be rotatable around the yaw axis Y. As shown in Figure 4, the hand 3 is attached to the rotating body 46. When the rotating body 46 rotates relative to the base body 45, the hand 3 rotates together with the rotating body 46 around the yaw axis Y relative to the base body 45.

[0032] =Link Mechanism= The link mechanism 6 includes a pair of first and second link mechanisms 6A and 6B arranged to face each other. Each of the first and second link mechanisms 6A and 6B movably connects the second base 42 to the first base 41. Each of the first and second link mechanisms 6A and 6B includes a Chebyshev link mechanism 60. The first and second link mechanisms 6A and 6B have the same configuration. The first and second link mechanisms 6A and 6B perform the same operation to move the second base 42.

[0033] The link mechanism 6 is connected to the first base 41 so as to be rotatable about the roll axis R. More specifically, the link mechanism 6 is attached to the rotating body 44 of the first base 41. When the rotating body 44 rotates about the roll axis R, the link mechanism 6 also rotates about the roll axis R. When the link mechanism 6 rotates about the roll axis R, the hand 3 rotates about the roll axis R together with the second base 42.

[0034] = Chebyshev Link Mechanism = The Chebyshev link mechanism 60 has a driver 61, a follower 62, and an intermediate link 63. The driver 61 is rotatably connected to the first base 41 around a predetermined drive axis D and is driven to rotate. The follower 62 is rotatably connected to the first base 41 around an axis parallel to the drive axis D. The intermediate link 63 is rotatably connected to the driver 61 and the follower 62 around an axis parallel to the drive axis D. More specifically, a shaft 65 is supported on the first base 41 so as to be rotatable about its axis. The rotation axis of the shaft 65 is the drive axis D. The driver 61 is non-rotatably connected to the shaft 65. That is, the driver 61 is rotatably connected to the first base 41 around the drive axis D via the shaft 65. The driver 61 and the shaft 65 are connected to the rotating body 44 of the first base 41. The follower 62 is connected to the rotating body 44 of the first base 41. The rotation axis of the follower 62 is spaced apart from the drive axis D of the driver 61 in a direction parallel to the linear direction Z. The second base 42, more specifically, the base main body 45, is connected to the intermediate link 63. The follower 62 is connected to a portion of the intermediate link 63 between the portion to which the driver 61 is connected and the portion to which the second base 42 is connected. When the driver 61 is rotationally driven, the follower 62 and intermediate link 63 move in conjunction with each other, and the second base 42 moves.

[0035] In the Chebyshev link mechanism 60, the link length of each link is appropriately set, so that the portion of the intermediate link 63 connected to the second base 42 moves approximately linearly in response to the rotation of the driver 61. Specifically, if the link length of the driver 61 is 1, the link length of the follower 62 is 2.5, the distance between the connecting portion of the driver 61 and the connecting portion of the follower 62 in the intermediate link 63 is 2.5, the distance between the connecting portion of the follower 62 and the connecting portion of the second base 42 in the intermediate link 63 is 2.5, and the distance between the drive axis D of the driver 61 and the rotation axis of the follower 62 is 2. As a result, when the driver 61 is rotationally driven, the portion of the intermediate link 63 connected to the second base 42, i.e., the second base 42, moves linearly. The direction of movement of the second base 42 substantially coincides with the translation direction Z.

[0036] The first link mechanism 6A and the second link mechanism 6B face each other in the direction of the drive axis D. That is, the opposing direction of the first link mechanism 6A and the second link mechanism 6B coincides with the direction of the drive axis D. In the direction of the drive axis D, the driver 61 of the first link mechanism 6A faces the driver 61 of the second link mechanism 6B, the follower 62 of the first link mechanism 6A faces the follower 62 of the second link mechanism 6B, and the intermediate link 63 of the first link mechanism 6A faces the intermediate link 63 of the second link mechanism 6B.

[0037] More specifically, each of the two mutually connected joints in the link mechanism overlaps in the direction of the drive axis D at the joint, and therefore are disposed at offset positions in the direction of the drive axis D. As shown in FIG. 5 , the driver 61 of the first link mechanism 6A is disposed inward of the intermediate joint 63 of the first link mechanism 6A in the opposing direction between the first link mechanism 6A and the second link mechanism 6B. The driver 61 of the second link mechanism 6B is disposed inward of the intermediate joint 63 of the second link mechanism 6B in the opposing direction between the first link mechanism 6A and the second link mechanism 6B. That is, the driver 61 of the first link mechanism 6A and the driver 61 of the second link mechanism 6B are disposed between the intermediate joint 63 of the first link mechanism 6A and the intermediate joint 63 of the second link mechanism 6B. Of the joints of the first link mechanism 6A and the second link mechanism 6B, the intermediate joint 63 of the first link mechanism 6A and the intermediate joint 63 of the second link mechanism 6B are disposed outermost in the opposing direction.

[0038] The driving link 61 of the first link mechanism 6A and the driving link 61 of the second link mechanism 6B are connected to a common shaft 65 .

[0039] The intermediate link 63 of the first link mechanism 6A and the intermediate link 63 of the second link mechanism 6B are connected to each other. Specifically, as shown in Fig. 5, the joint 64a connecting the driver link 61 and the intermediate link 63 of the first link mechanism 6A and the joint 64a connecting the driver link 61 and the intermediate link 63 of the second link mechanism 6B are connected to each other. More specifically, the joint 64a of the first link mechanism 6A and the joint 64a of the second link mechanism 6B are connected to each other via a shaft 66 extending parallel to the drive axis D. The driver link 61 and the intermediate link 63 of the first link mechanism 6A are rotatably connected to one end of the shaft 66. The driver link 61 and the intermediate link 63 of the second link mechanism 6B are rotatably connected to the other end of the shaft 66.

[0040] =First Actuator= The first actuator 51 is an electric motor, specifically a servo motor. The first actuator 51 is provided with an encoder. The first actuator 51 is attached to the first base 41, more specifically, to the rotating body 44. As shown in FIG. 5 , the first actuator 51 is disposed between the first link mechanism 6A and the second link mechanism 6B.

[0041] FIG. 6 is a cross-sectional view of the wrist 4 taken along line VI-VI in FIG. 5. The rotation of the first actuator 51 is transmitted to the Chebyshev link mechanism 60 via a linear transmission mechanism 71. The linear transmission mechanism 71 includes a worm gear. Specifically, the linear transmission mechanism 71 includes a worm 72 attached to the output shaft of the first actuator 51 and a worm wheel 73 connected to the driver 61 of the Chebyshev link mechanism 60 and meshing with the worm 72. The worm 72 rotates integrally with the output shaft. The worm wheel 73 is non-rotatably attached to the shaft 65. That is, the worm wheel 73 is connected to the driver 61 via the shaft 65.

[0042] When the first actuator 51 operates, the worm 72 rotates. The worm wheel 73 rotates in conjunction with the worm 72, and the shaft 65 rotates integrally with the worm wheel 73. Because the driver 61 is non-rotatably connected to the shaft 65, the driver 61 rotates integrally with the shaft 65 around the drive axis D. In this manner, the Chebyshev link mechanism 60 is driven by the first actuator 51. Because the driver 61 of both the first link mechanism 6A and the second link mechanism 6B is connected to the shaft 65, the Chebyshev link mechanism 60 of the first link mechanism 6A and the Chebyshev link mechanism 60 of the second link mechanism 6B operate integrally.

[0043] =Linear Operation= The operation of the wrist 4 by the Chebyshev link mechanism 60 will be described in detail. Fig. 7 is a side view of the wrist 4 in an advanced state. Fig. 8 is a side view of the wrist 4 in a state in which the hand 3 has advanced to the most advanced position in the linear direction Z. Fig. 9 is a perspective view of the wrist 4 in a state in which the hand 3 has advanced to the most advanced position in the linear direction Z. Note that the hand 3 is omitted from Fig. 9. The advanced state of the wrist 4 is a state in which the wrist 4 has moved from the basic state in the linear direction Z.

[0044] In the Chebyshev link mechanism 60, in a certain section (hereinafter referred to as the "specific section") of one rotation of the driver 61, the tip of the intermediate link 63, i.e., the end of the intermediate link 63 opposite the end to which the driver 61 is connected, moves substantially linearly. The direction of movement of the tip of the intermediate link 63 substantially coincides with the translational direction Z. Specifically, the tip of the intermediate link 63 moves linearly between a first position and a second position in the translational direction Z. The second position is farther from the drive axis D of the driver 61 in the translational direction Z than the first position. In other words, movement of the intermediate link 63 toward the second position in the translational direction Z is movement away from the drive axis D of the driver 61, and is also expressed as "advancing." Movement of the intermediate link 63 toward the first position in the translational direction Z is movement toward the drive axis D of the driver 61, and is also expressed as "retreating." In the basic state of the wrist 4, the tip of the intermediate link 63 is located at the first position. The positions of the second base 42, the hand 3, etc. when the tip of the intermediate link 63 is located at the first position are also referred to as the "first position." The positions of the second base 42, the hand 3, etc. when the tip of the intermediate link 63 is located at the second position are also referred to as the "second position." For example, the first position of the hand 3 is the position of the hand 3 when the tip of the intermediate link 63 is located at the first position.

[0045] When the driver 61 is in the state shown in FIG. 4 , the tip of the intermediate link 63 is located at the first position. Note that the tip of the intermediate link 63 is also located at the first position in FIGS. 3 and 5 . When the driver 61 rotates clockwise (in the direction of the arrow in the figure) from the state shown in FIG. 4 , the tip of the intermediate link 63 moves linearly toward the second position in the translational direction Z (downward in the figure), as shown in FIG. 7 . When the driver 61 reaches the state shown in FIG. 8 , the tip of the intermediate link 63 reaches the second position in the translational direction Z. When the driver 61 rotates counterclockwise from the state shown in FIG. 8 , the tip of the intermediate link 63 moves linearly toward the first position in the translational direction Z. When the driver 61 reaches the state shown in FIG. 4 , the tip of the intermediate link 63 reaches the first position in the translational direction Z.

[0046] 8 to the state shown in FIG. 4, the tip of the intermediate link 63 also returns to the first position. However, the trajectory of the tip of the intermediate link 63 at this time is not linear but curved.

[0047] In this way, in a specific section of rotation of the driver 61, the tip of the intermediate link 63 moves linearly. The second base 42 is connected to the tip of the intermediate link 63, and the hand 3 is attached to the second base 42. In other words, the hand 3 moves linearly. By rotating the driver 61 within the specific section, the hand 3 can be moved substantially forward and backward in the linear direction Z. Depending on the direction of rotation of the driver 61 in this specific section, it is determined whether the tip of the intermediate link 63, i.e., the hand 3, moves toward the first position or the second position in the linear direction Z.

[0048] =Pitch Transmission Mechanism= The second base 42 is connected to the intermediate link 63 so as to be rotatable around the pitch axis P. Specifically, as shown in FIG. 3 , the intermediate link 63 of the first link mechanism 6A and the intermediate link 63 of the second link mechanism 6B face each other in the direction of the drive axis D. The second base 42 is connected to the two intermediate links 63 so as to be rotatable around the pitch axis P. The pitch axis P is parallel to the drive axis D. In other words, the pitch axis P is perpendicular to the plane in which each link of the link mechanism 6 moves. The pitch transmission mechanism 8 is connected to the second base 42. The second base 42 includes a rotor 46 that is rotatable around the yaw axis Y. The yaw axis Y extends in a direction intersecting the direction of the pitch axis P.

[0049] As shown in FIG. 4, the pitch transmission mechanism 8 includes a four-bar link mechanism 80. The four-bar link mechanism 80 is a parallel link mechanism. The intermediate link 63 of the Chebyshev link mechanism 60 functions as a node included in the four-bar link mechanism 80. In this example, as shown in FIG. 5, the pitch transmission mechanism 8 includes a four-bar link mechanism 80 corresponding to the first link mechanism 6A and a four-bar link mechanism 80 corresponding to the second link mechanism 6B. The four-bar link mechanism 80 corresponding to the first link mechanism 6A and the four-bar link mechanism 80 corresponding to the second link mechanism 6B have the same configuration.

[0050] 4 , the four-bar link mechanism 80 includes a first four-bar link mechanism 81 connected to the second base 42, and a second four-bar link mechanism 82 connected to the first four-bar link mechanism 81 and driven by the second actuator 52. The intermediate link 63 of the Chebyshev link mechanism 60 functions as a node included in the first four-bar link mechanism 81, and the driven link 62 of the Chebyshev link mechanism 60 functions as a node included in the second four-bar link mechanism 82.

[0051] Specifically, the first four-link linkage 81 includes a first fixed link 83, a first driver link 84 rotatably connected to the first fixed link 83 about an axis parallel to the pitch axis P, a first follower link 85 rotatably connected to the first fixed link 83 about an axis parallel to the pitch axis P, and a first intermediate link 86 rotatably connected to each of the first driver link 84 and the first follower link 85 about an axis parallel to the pitch axis P. The first fixed link 83 is the intermediate link 63 of the Chebyshev linkage 60. The first follower link 85 is fixed to the second base 42. More specifically, the first follower link 85 is part of the base body 45 of the second base 42. The first intermediate link 86 is disposed opposite the first fixed link 83. The first four-link linkage 81 is a parallel linkage. The four joints connecting the first fixed link 83, the first driving link 84, the first driven link 85 and the first intermediate link 86 are arranged substantially at the vertices of a parallelogram.

[0052] The second four-link linkage 82 includes a second fixed link 87, a second driver link 88 rotatably connected to the second fixed link 87 about an axis parallel to the pitch axis P, a second follower link 89 rotatably connected to the second fixed link 87 about an axis parallel to the pitch axis P, and a second intermediate link 810 rotatably connected to each of the second driver link 88 and the second follower link 89 about an axis parallel to the pitch axis P. The second fixed link 87 is the follower link 62 of the Chebyshev linkage 60. The second intermediate link 810 is located opposite the second fixed link. The second four-link linkage 82 is a parallel linkage. The four joints connecting the second fixed link 87, the second driver link 88, the second follower link 89, and the second intermediate link 810 are located substantially at the vertices of a parallelogram.

[0053] 4, dashed lines indicate straight line segments that define the link lengths of the first four-bar link mechanism 81 and the second four-bar link mechanism 82. The same applies to FIGS.

[0054] The second follower 89 is connected to the first driver 84. The second follower 89 is connected to the first driver 84 via a connecting joint 811. When the second follower 89 moves, the first driver 84 moves in conjunction with the second follower 89. More specifically, both the first driver 84 and the second follower 89 are connected to the connecting portion between the follower 62 and the intermediate joint 63. The first driver 84, the second follower 89, and the connecting joint 811 are integrally formed. The relative positions of the first driver 84, the second follower 89, and the connecting joint 811 are fixed. In this example, the first driver 84, the second follower 89, and the connecting joint 811 are formed of substantially triangular plates. When the second follower 89 moves, the first driver 84 and the connecting joint 811 move in conjunction with the second follower 89.

[0055] The second driver 88 is rotationally driven by the second actuator 52. As shown in FIG. 6 , a shaft 812 that is rotationally driven by the second actuator 52 is coupled to the second driver 88. More specifically, the shaft 812 is supported on the first base 41 so as to be rotatable about its axis. The rotation axis E of the shaft 812, i.e., the axis, is parallel to the drive axis D. The second driver 88 is non-rotatably coupled to the shaft 812. That is, the second driver 88 is coupled to the first base 41 via the shaft 812 so as to be rotatable about the rotation axis E. The second driver 88 and the shaft 812 are coupled to the rotating body 44 of the first base 41. The follower 62 is coupled to the shaft 812 so as to be rotatable about the rotation axis E. That is, the follower 62 is rotatably coupled to the first base 41 and the second driver 88 via the shaft 812.

[0056] When the shaft 812 is driven to rotate, the second driver 88 rotates integrally with the shaft 812. On the other hand, the follower 62 does not rotate integrally with the shaft 812. When the second driver 88 rotates, the second intermediate link 810 and the second follower 89 move in conjunction with the rotation of the second driver 88. When the second follower 89 moves, the first driver 84 of the first four-link linkage 81 rotates in conjunction with the second follower 89. When the first driver 84 rotates, the first intermediate link 86 and the first follower 85 move in conjunction with the rotation of the first driver 84. Because the first follower 85 is formed integrally with the second base 42, the second base 42 rotates around the pitch axis P. Note that the rotation of the second driver 88 does not affect the first fixed link 83 and the second fixed link 87, i.e., the Chebyshev linkage 60.

[0057] In this way, when the second driving link 88 is rotationally driven, the second base 42 and the hand 3 rotate around the pitch axis P without affecting the Chebyshev link mechanism 60 .

[0058] = Second Actuator = The second actuator 52 is an electric motor, specifically a servo motor. The second actuator 52 is provided with an encoder. As shown in FIG. 5 , the second actuator 52 is attached to the first base 41, more specifically, to the rotating body 44. The second actuator 52 is disposed between the first link mechanism 6A and the second link mechanism 6B.

[0059] The rotation of the second actuator 52 is transmitted to the four-bar linkage 80 via a worm gear. Specifically, as shown in FIG. 6 , a worm 74 is attached to the output shaft of the second actuator 52. The worm 74 rotates integrally with the output shaft. A worm wheel 75 is connected to a second driver link 88 of the four-bar linkage 80. The worm wheel 75 is attached to a shaft 812 so as not to rotate. In other words, the worm wheel 75 is connected to the second driver link 88 via the shaft 812. The worm 74 and the worm wheel 75 mesh with each other.

[0060] When the second actuator 52 operates, the worm 74 rotates. The worm wheel 75 rotates in conjunction with the worm 74, and the shaft 812 rotates integrally with the worm wheel 75. Because the second driver 88 is non-rotatably connected to the shaft 812, the second driver 88 rotates integrally with the shaft 812 around the rotation axis E. In this manner, the four-bar linkage 80 is driven by the second actuator 52. Because the second driver 88 of the four-bar linkage 80 corresponding to the first linkage 6A and the second driver 88 of the four-bar linkage 80 corresponding to the second linkage 6B are connected to the shaft 812, the second driver 88 of the two four-bar linkages 80 operate integrally.

[0061] =Pitch Movement= Next, the pitch movement of the wrist 4 will be described. Figure 10 is a side view of the wrist 4 after the pitch movement. In Figure 10, the wrist 4 is rotated around the pitch axis P from the basic state in Figure 4. In this example, the pitch angle is set to 0 degrees when the fingers 32 extend in the linear direction Z, that is, when the yaw axis Y points in the linear direction Z. The direction in which the tips of the fingers 32 rotate away from the first base 41 from a state in which the pitch angle is 0 degrees is set to positive. The hand 3 in Figure 10 has rotated approximately 90 degrees around the pitch axis P.

[0062] When the Chebyshev link mechanism 60 is not moving, the follower 62 (i.e., the second fixed link 87) and the intermediate link 63 (i.e., the first fixed link 83) do not move. When the second driver 88 is rotationally driven by the second actuator 52, the second intermediate link 810 and the second follower 89 move in conjunction with the second driver 88. Because the relative positional relationship between the first driver 84 and the second follower 89 remains unchanged, the first driver 84 rotates in conjunction with the movement of the second follower 89. When the first driver 84 rotates, the first intermediate link 86 and the first follower 85 move in conjunction with the first driver 84. The first follower 85 rotates around the pitch axis P. The first follower 85 is integrally formed with the second base 42, and the hand 3 is attached to the second base 42. In other words, the hand 3 rotates around the pitch axis P. The pitch angle, which is the angle of the second base 42 around the pitch axis P, is adjusted by the rotation angle of the second driving link 88.

[0063] When the Chebyshev link mechanism 60 operates, the follower 62 and the intermediate link 63 move, and therefore the four-bar link mechanism 80 also moves. However, when the second driver 88 is not rotationally driven, the angle of the first follower 85 does not change, and the pitch angle of the hand 3 is maintained, as shown in FIGS. 4, 7, and 8 . In other words, the pitch transmission mechanism 8 maintains the pitch angle of the second base 42 about the pitch axis P when the second base 42 moves in the translatory direction Z via the Chebyshev link mechanism 60. The attitude of the first driver 84, which is a node located opposite the first follower 85, which is a node integral with the second base 42, is maintained and does not change during operation of the Chebyshev link mechanism 60.

[0064] Specifically, because the second four-bar link mechanism 82 is a parallel link mechanism, the angle between the opposing second driver 88 and second follower 89 does not change in FIGS. 4, 7, and 8. In other words, if the second driver 88 does not rotate, the angle of the second follower 89 does not change even if the second follower 89 moves. Furthermore, because the second follower 89 and the first driver 84 are integrally connected, the relative positional relationship between the second follower 89 and the first driver 84 does not change. In other words, if the angle of the second follower 89 does not change, the angle of the first driver 84 does not change even if the first driver 84 moves. Furthermore, because the first four-bar link mechanism 81 is a parallel link mechanism, the angle between the opposing first driver 84 and first follower 85 does not change. In other words, if the angle of the first driver 84 does not change, the angle of the first follower 85 does not change even if the first driver 84 moves. In short, even if the second follower 89, the first driver 84, and the first follower 85 move in accordance with the operation of the Chebyshev link mechanism 60, unless the second driver 88 rotates, the angles of the second follower 89, the first driver 84, and the first follower 85 do not change.

[0065] In other words, the pitch angle of the hand 3 depends on the rotation angle of the second driver 88 and is not affected by the state of the Chebyshev link mechanism 60. Whether the Chebyshev link mechanism 60 is stopped or operating, when the second driver 88 is rotationally driven, the pitch angle of the hand 3 changes according to the rotation angle of the second driver 88. Whether the Chebyshev link mechanism 60 is stopped or operating, when the second driver 88 is not rotating, the pitch angle of the hand 3 is maintained.

[0066] In the pitch transmission mechanism 8, the shaft 812 is connected to the second driver link 88. Therefore, as shown in FIG. 11 , depending on the state of the pitch transmission mechanism 8, the second intermediate link 810 approaches the shaft 812. FIG. 11 is a side view of the wrist 4 when the hand 3 is advanced to the maximum in the linear direction Z and the pitch angle is 90 degrees. The second intermediate link 810 is curved to avoid interference with the shaft 812 when it approaches the shaft 812 in conjunction with the second driver link 88. In other words, when the angle formed between the second driver link 88 and the second fixed link 87 is large, the second intermediate link 810 approaches the shaft 812. The second intermediate link 810 has a curved portion 810 a at a portion approaching the shaft 812 that is curved so as to be recessed toward the side away from the shaft 812. The curved portion 810 a of the second intermediate link 810 makes it less likely for the second intermediate link 810 to interfere with the shaft 812. This increases the range of motion of the second intermediate section 810, and as a result, the range of pitch motion of the wrist 4 is increased.

[0067] =Third Actuator= The third actuator 53 is an electric motor, specifically a servo motor. The third actuator 53 is provided with an encoder. As shown in FIG. 5 , the third actuator 53 is attached to the first base 41, more specifically, to the base main body 43.

[0068] The rotation of the third actuator 53 is transmitted to the rotating body 44 via a roll transmission mechanism 76. The roll transmission mechanism 76 includes a gear train. Specifically, the roll transmission mechanism 76 includes a first gear 77 attached to the output shaft of the third actuator 53 and a second gear 78 attached to the rotating body 44. The first gear 77 rotates integrally with the output shaft. The second gear 78 is attached to the rotating body 44 so as to be non-rotatable. The second gear 78 meshes with the first gear 77.

[0069] =Rolling Motion= Next, the rolling motion of the wrist 4 will be described. Figure 12 is a perspective view of the wrist 4 after the rolling motion. In Figure 12, the link mechanism 6 has been rotated around the roll axis R from the basic state of Figure 4. In this example, the roll angle is defined as 0 degrees when the rectilinear direction Z extends vertically and the fingers 32 extend downward from the hand body 31. The clockwise direction when viewed facing the first base 41 in the direction of the roll axis R is defined as positive. The link mechanism 6 in Figure 12 has rotated approximately 90 degrees around the roll axis R.

[0070] When the third actuator 53 operates, the first gear 77 rotates. The second gear 78 rotates in conjunction with the first gear 77, and the rotating body 44 rotates integrally with the second gear 78 around the roll axis R. The link mechanism 6 is connected to the rotating body 44. The link mechanism 6 is connected to the second base 42. In this way, the third actuator 53 rotates the second base 42 around the roll axis R. Since the hand 3 is connected to the second base 42, the hand 3 rotates around the roll axis R. The pitch transmission mechanism 8 also rotates integrally with the rotating body 44 around the roll axis R.

[0071] 13 is a front view of the wrist 4 with the link mechanism 6 rotated about the roll axis R. Because the link mechanism 6 rotates about the roll axis R, the translation direction Z and the pitch axis P also rotate about the roll axis R. In other words, by rotating the link mechanism 6 about the roll axis R, the direction in which the hand 3 moves linearly can be changed, and the direction of the pitch axis P for the pitch movement of the wrist 4 can also be changed.

[0072] =Fourth Actuator= The fourth actuator 54 is an electric motor, specifically a servo motor. The fourth actuator 54 is provided with an encoder. As shown in FIG. 3 , the fourth actuator 54 is attached to the second base 42, more specifically, to the base main body 45. The fourth actuator 54 is disposed between the first link mechanism 6A and the second link mechanism 6B.

[0073] =Yaw Transmission Mechanism= The rotation of the fourth actuator 54 is transmitted to the rotating body 46 via a yaw transmission mechanism 79. The yaw transmission mechanism 79 includes a transmission belt and a worm gear. Specifically, a shaft 47 is supported on the base main body 45 so as to be rotatable about its axis. The yaw transmission mechanism 79 includes a pulley attached to the output shaft of the fourth actuator 54, a pulley attached to the shaft 47, a belt wound around the two pulleys, a worm 710 attached to the shaft 47, and a worm wheel 711 attached to the rotating body 46. The worm 710 is non-rotatably attached to the shaft 47 and rotates integrally with the shaft 47. The worm wheel 711 is non-rotatably attached to the rotating body 46 and meshes with the worm 710. The yaw axis Y passes through the center of the worm wheel 711.

[0074] When the fourth actuator 54 operates, the shaft 47 rotates via the two pulleys and the belt. The worm 710 rotates together with the shaft 47, and the worm wheel 711 rotates in conjunction with the worm 710. The rotating body 46 rotates integrally with the worm wheel 711.

[0075] = Yaw Movement = Next, the yaw movement of the wrist 4 will be described. Fig. 14 is a side view of the wrist 4 after the yaw movement. In Fig. 14, the wrist 4 rotates the hand 3 around the yaw axis Y from the basic state in Fig. 4. In this example, the yaw angle is set to 0 degrees when the opening and closing direction of the fingers 32 is parallel to the roll axis R. The hand 3 in Fig. 14 has rotated approximately 90 degrees around the yaw axis Y.

[0076] When the fourth actuator 54 rotates the rotating body 46 about the yaw axis Y, the hand 3 rotates integrally with the rotating body 46 about the yaw axis Y. When the wrist 4 performs a yaw movement, the opening and closing directions of the fingers 32 change. In FIG. 4 , the opening and closing directions of the fingers 32 are parallel to the roll axis R. On the other hand, in FIG. 14 , the opening and closing directions of the fingers 32 are perpendicular to the roll axis R.

[0077] Furthermore, since the hand 3 is supported on the second base 42 so as to be rotatable around the yaw axis Y, when the second base 42 moves by roll and / or pitch movement, the direction of the yaw axis Y also changes according to the second base 42.

[0078] The wrist 4 configured in this manner flexibly moves the hand 3 by translatory movement, pitch movement, roll movement, and yaw movement. For example, when the robot arm 2 moves the hand 3 to the workspace H, i.e., above the first container C1, the wrist 4 positions the hand 3 at a first position in the translatory direction Z. At this time, the translatory direction Z faces the vertical direction, and the second position is located lower than the first position. The roll axis R faces the horizontal direction. The pitch axis P faces the horizontal direction. The yaw axis Y faces the vertical direction. Because the hand 3 is positioned at the first position, the overall size of the hand 3 and wrist 4 in the translatory direction Z is reduced. This makes it easier for the hand 3 and wrist 4 to enter a narrow space such as the workspace H.

[0079] From this state, the wrist 4 moves the hand 3 toward the second position in the linear direction Z via the Chebyshev link mechanism 60. As a result, the hand 3 moves linearly downward and enters the first container C1. When the hand 3 reaches the workpiece W, the hand 3 grasps the workpiece W with the fingers 32.

[0080] After gripping the workpiece W, the wrist 4 moves the hand 3 toward the first position in the linear direction Z via the Chebyshev link mechanism 60. As a result, the hand 3 moves linearly upward and exits the first container C1.

[0081] Thereafter, the robot arm 2 causes the hand 3 and the wrist 4 to withdraw from the workspace H. This completes the picking of the workpiece W. At this time, because the hand 3 is disposed at the first position, the overall size of the hand 3 and the wrist 4 in the linear direction Z is reduced. This makes it easier for the hand 3 and the wrist 4 to withdraw from a small space such as the workspace H.

[0082] When the hand 3 enters the first container C1, the wrist 4 can move the hand 3 in various ways. For example, when the wrist 4 performs a roll motion, the orientation of the linear direction Z changes as shown in FIG. 13 . In other words, the linear direction Z is tilted relative to the vertical direction. From this state, the wrist 4 moves the hand 3 toward the second position in the linear direction Z, causing the hand 3 to move linearly diagonally downward. This allows the arrival position of the hand 3 to be adjusted without moving the robot arm 2.

[0083] As a result of adjusting the reach position of the hand 3, the reach range of the hand 3 can be expanded. Figures 15, 16, and 17 are explanatory diagrams of the procedure for expanding the reach range of the hand 3. Figure 15 is a front view of the hand 3 and wrist 4 positioned above the first container C1. Figure 16 is a front view of the hand 3 and wrist 4 after a roll motion. Figure 17 is a front view of the hand 3 and wrist 4 after a rectilinear motion. For example, if a workpiece W is placed near the side wall of the first container C1, moving the hand 3 vertically from above toward the workpiece W may cause the hand 3 to interfere with the side wall of the first container C1. In such a case, as shown in Figure 15, the hand 3 is positioned away from the side wall of the first container C1. Then, as shown in Figure 16, the wrist 4 rolls to direct the rectilinear direction Z toward the workpiece W near the side wall. Next, as shown in Figure 17, the wrist 4 moves the hand 3 diagonally downward in a straight line by a rectilinear motion. This allows the hand 3 to reach the workpiece W while avoiding interference with the side wall.

[0084] Furthermore, the opening and closing directions of the fingers 32 can be changed by yaw motion of the wrist 4. FIG. 18 is a side view of the hand 3 and wrist 4 before yaw motion when picking multiple adjacent workpieces W. FIG. 19 is a side view of the hand 3 and wrist 4 after yaw motion when picking multiple adjacent workpieces W. For example, a workpiece W may be positioned adjacent to another object, such as another workpiece W. In such a case, as shown in FIG. 18 , if the arrangement direction of the multiple workpieces W and the opening and closing direction of the fingers 32 coincide, the fingers 32 may interfere with the other workpieces W, making it impossible to properly grasp the target workpiece W. By yaw motion of the wrist 4, the opening and closing direction of the fingers 32 can be made different from the arrangement direction of the multiple workpieces W, as shown in FIG. 19 . This allows the fingers 32 to properly grasp the target workpiece W without interfering with other workpieces W. In this way, the yaw motion of the wrist 4 allows the opening and closing direction of the fingers 32 to be adjusted according to the situation around the workpiece W.

[0085] Furthermore, the direction in which the fingers 32 extend can be changed by the wrist 4 performing a pitch motion. FIG. 20 is a side view of the hand 3 and wrist 4 when the hand 3 gripping the workpiece W is retracted in the linear direction Z. FIG. 21 is a side view of the hand 3 and wrist 4 when the hand 3 gripping the workpiece W is rotated around the pitch axis P. For example, the direction of the workpiece W gripped by the fingers 32 can be flexibly changed. The workpiece W gripped by the fingers 32 is usually suspended in the linear direction Z. As shown in FIG. 20 , when the workpiece W is large, the overall size of the hand 3 and wrist 4 including the workpiece W in the linear direction Z increases. When the overall size of the hand 3 and the like in the linear direction Z is large, high-precision position control of the hand 3 and the like may be required when the robot arm 2 retracts the hand 3 and the like from the workspace H. In some cases, the workpiece W may interfere with the first container C1. In such a case, as shown in FIG. 21 , by pitching the wrist 4 so that the yaw axis Y is approximately parallel to the advance / retract axis V, the workpiece W extends from the fingers 32 in the direction of the advance / retract axis V. This reduces the overall size of the hand 3 and wrist 4, including the workpiece W, in the linear direction Z. As a result, the robot arm 2 can easily remove the hand 3 and the like from the workspace H. In addition, the wrist 4 may also adjust the position of the hand 3 in the linear direction Z. Depending on the pitching motion of the wrist 4, the hand 3 or wrist 4 may protrude in the linear direction Z relative to the robot arm 2 (see FIG. 10 ). By adjusting the position of the hand 3 in the linear direction Z so that the wrist 4 approaches the advance / retract axis V, the overall size of the robot arm 2, hand 3, and wrist 4 in the linear direction Z can be reduced.

[0086] In this way, the wrist 4 flexibly moves the hand 3, allowing the hand 3 to appropriately pick up workpieces W that are placed in complicated locations where the movement of the robot arm 2 is restricted. In other words, it is difficult to move the hand 3 into the first container C1 using only the movement of the robot arm 2. By moving the hand 3 in the linear direction Z using the wrist 4, the hand 3 can be moved into the first container C1 without moving the robot arm 2. In this case, because the wrist 4 moves the hand 3 linearly, it is easier to manage the position of the hand 3 compared to when the hand 3 moves in a curved line. For example, it is easier to avoid interference between the hand 3 and other objects.

[0087] Furthermore, the link mechanism 6 employs a Chebyshev link mechanism 60 for movement of the hand 3. The amount of linear movement achieved by the Chebyshev link mechanism 60 is relatively large. In other words, the stroke of the hand 3 in the linear direction Z can be increased while preventing the link mechanism 6 from becoming too large. The Chebyshev link mechanism 60 operates when the driving link 61 is rotationally driven. Therefore, the Chebyshev link mechanism 60 is driven by a motor. For example, linear movement of the hand 3 can also be achieved by a combination of a linear guide and a cylinder, etc. However, a motor has higher controllability than a cylinder, etc. By employing the Chebyshev link mechanism 60, the movement of the hand 3 in the linear direction Z can be easily and accurately controlled.

[0088] In addition, when operating the wrist 4, the moving parts are smaller and lighter than when operating the robot arm 2. Smaller moving parts reduce the possibility of interference with other parts. Lighter moving parts reduce the driving force required for movement and improve controllability. In other words, the wrist 4 has these advantages even when operating in places other than complicated locations.

[0089] The link mechanism 6 supports the second base 42 by means of the opposing first link mechanism 6A and second link mechanism 6B. This improves the support rigidity of the second base 42. Furthermore, the first link mechanism 6A and the second link mechanism 6B are connected by a shaft 66. This improves the rigidity of the link mechanism 6.

[0090] The driver 61 of the first link mechanism 6A and the driver 61 of the second link mechanism 6B are connected by a shaft 65 and driven by a common first actuator 51 via the shaft 65. This reduces the number of drive sources for the first link mechanism 6A and the second link mechanism 6B. Furthermore, as shown in FIG. 3 , two driver links 61 are arranged between the intermediate link 63 of the first link mechanism 6A and the intermediate link 63 of the second link mechanism 6B in the opposing direction of the first link mechanism 6A and the second link mechanism 6B. With this arrangement, the two intermediate links 63 move outside the shaft 65, preventing interference between the intermediate links 63 and the shaft 65.

[0091] 5, two four-bar link mechanisms 80 are disposed between the intermediate link 63 of the first link mechanism 6A and the intermediate link 63 of the second link mechanism 6B in the opposing direction. This allows the two four-bar link mechanisms 80 to be disposed compactly in the direction of the drive axis D.

[0092] Furthermore, the first intermediate link 86 and the second intermediate link 810 are arranged in a plane perpendicular to the opposing direction of the first link mechanism 6A and the second link mechanism 6B, i.e., in a plane perpendicular to the drive axis D. The first intermediate link 86 is included in the first four-bar link mechanism 81, and the second intermediate link 810 is included in the second four-bar link mechanism 82. Therefore, the first intermediate link 86 and the second intermediate link 810 hardly overlap with each other in the direction of the drive axis D. Even if the first intermediate link 86 and the second intermediate link 810 are arranged in the same plane perpendicular to the drive axis D, the first intermediate link 86 and the second intermediate link 810 do not interfere with each other. By arranging the first intermediate link 86 and the second intermediate link 810 in the same plane, the size of the four-bar link mechanism 80 in the direction of the drive axis D can be reduced.

[0093] Furthermore, the pitch transmission mechanism 8 transmits the driving force of the second actuator 52 to the second base 42 by a link mechanism. Therefore, the pitch transmission mechanism 8 can be made smaller in size than a configuration that transmits driving force using a cylinder or the like.

[0094] Some of the nodes included in the Chebyshev link mechanism 60 function as nodes included in the pitch transmission mechanism 8. By sharing some of the nodes of the Chebyshev link mechanism 60 with some of the nodes of the pitch transmission mechanism 8, the configuration of the wrist 4 can be simplified.

[0095] The four-bar linkage mechanism 80 included in the pitch transmission mechanism 8 is a parallel linkage mechanism, which makes it easy to manage the pitch angle of the second base 42, and therefore the pitch angle of the hand 3. In the four-bar linkage mechanism 80, the angles of each of the two opposing nodes are substantially the same. Even when the four-bar linkage mechanism 80 is linked to the Chebyshev linkage mechanism 60, the pitch angle of the hand 3 can be kept constant by maintaining the angle of the node opposing the node fixed to the second base 42. As a result, the hand 3 can be moved linearly in the rectilinear direction Z without changing the pitch angle of the hand 3.

[0096] The length of the driver 61 of the Chebyshev link mechanism 60 is equal to or longer than the lengths of the first driver 84, the first follower 85, and the second follower 89. This allows the wrist 4 to be deformed compactly in the translational direction Z. Specifically, the Chebyshev link mechanism 60 operates by rotation of the driver 61. As shown in FIG. 7 , depending on the rotation angle, the driver 61 may protrude further toward the retreating side in the translational direction Z than the drive axis D. Each of the first driver 84, the first follower 85, and the second follower 89 may also face the retreating side in the translational direction Z. For example, as shown in FIG. 4 , when the tip of the intermediate link 63 is located in the first position, the first driver 84, the first follower 85, and the second follower 89 are located relatively farther toward the retreating side in the translational direction Z. In this position, the first driver 84, the first follower 85, and the second follower 89 can each face backward in the translational direction Z, depending on the angle of the second driver 88 (see FIGS. 4 and 10 ). The length of the driver 61 is longer than or equal to the length of any of the first driver 84, the first follower 85, and the second follower 89. Therefore, even if each of the first driver 84, the first follower 85, and the second follower 89 reaches its maximum protrusion in the translational direction Z, it only protrudes to approximately the same extent as the driver 61 that reaches its maximum protrusion in the translational direction Z. In other words, it is possible to prevent any of the first driver 84, the first follower 85, and the second follower 89 from protruding in the translational direction Z farther than the movement range of the driver 61. This prevents the size of the wrist 4 in the backward direction of the linear movement direction Z from expanding beyond the range of movement of the driving link 61.

[0097] Other Embodiments As described above, the above-described embodiments have been described as examples of the technology disclosed in the present application. However, the technology of the present disclosure is not limited to these embodiments and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate. Furthermore, the components described in the above-described embodiments can be combined to create new embodiments. Furthermore, the components described in the accompanying drawings and detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem in order to exemplify the technology. Therefore, the fact that these non-essential components are described in the accompanying drawings or detailed description should not be interpreted as immediately determining that these non-essential components are essential.

[0098] For example, the work performed by the robot 1 is not limited to transfer work. The robot 1 may also perform work such as assembling parts. In the case of transfer work, the robot 1 may pick a workpiece W from the second container C2 and place it in the first container C1. The wrist 4 can flexibly move the hand 3 by performing the linear movement, pitch movement, roll movement, and yaw movement as described above when placing the workpiece W. The wrist 4 may also perform the linear movement, pitch movement, roll movement, and yaw movement as described above when picking the workpiece W from the second container C2. The workpiece W before and after transfer does not have to be placed in a container. For example, the workpiece W before transfer may be placed on a tray, pallet, or conveyor. The workpiece W after transfer may be placed on a tray, pallet, or conveyor.

[0099] The processing by the hand 3 is not limited to holding a workpiece. For example, the processing by the hand 3 may be machining, welding, painting, etc. Holding a workpiece by the hand 3 is not limited to gripping, but may be by suction or the like.

[0100] Utilization of the movement of the wrist 4 is not limited to small spaces that restrict the movement of the robot arm 2. Even in an environment where the movement of the robot arm 2 is not restricted, operating the hand 3 with the wrist 4 has the effect of reducing the driving force and improving controllability.

[0101] The pitch, roll, and yaw movements by the wrist 4 are not essential. The wrist 4 only needs to linearly move the hand 3 via at least the Chebyshev link mechanism 60. For example, the wrist 4 may combine at least one of the pitch, roll, and yaw movements with the linear movement by the Chebyshev link mechanism 60.

[0102] The link mechanism 6 includes two link mechanisms, a first link mechanism 6A and a second link mechanism 6B. However, the link mechanism 6 may include only one of the first link mechanism 6A and the second link mechanism 6B. Alternatively, the link mechanism 6 may include three or more link mechanisms.

[0103] Regarding the roll operation, the rotating body 44 is rotatably connected to the base main body 43 of the first base 41 around the roll axis R. This causes the link mechanism 6, the second base 42, and the hand 3 to rotate around the roll axis R. However, the configuration related to the roll operation is not limited to this. The second base 42 may be configured with a divided body that can rotate around the roll axis. In this case, the link mechanism 6 does not rotate around the roll axis R, but the hand 3 rotates around the roll axis R.

[0104] Regarding the pitch movement, the second base 42 is connected to the link mechanism 6 so as to be rotatable about the pitch axis P. This causes the hand 3 to rotate about the pitch axis P. However, the configuration related to the pitch movement is not limited to this. The first base 41 may be configured as a divided body that is rotatable about the pitch axis. In this case, the link mechanism 6, the second base 42, and the hand 3 rotate about the pitch axis.

[0105] Regarding the yaw movement, the rotor 46 is connected to the base main body 45 of the second base 42 so as to be rotatable about the yaw axis Y. This causes the hand 3 to rotate about the yaw axis Y. However, the configuration related to the yaw movement is not limited to this. The first base 41 may be configured with divided bodies that are rotatable about the yaw axis. In this case, the link mechanism 6, the second base 42, and the hand 3 rotate about the yaw axis.

[0106] The technology of the present disclosure can be summarized as follows.

[0107] [1] The robot wrist 4 comprises a first base 41 attached to the robot arm 2, a second base 42 attached to the hand 3, a link mechanism 6 movably connecting the second base 42 to the first base 41, and a first actuator 51 driving the link mechanism 6, the link mechanism 6 including a Chebyshev link mechanism 60 connecting the second base 42 to the first base 41 so as to be linearly movably in a predetermined rectilinear direction Z, the Chebyshev link mechanism 60 having a driver 61 connected to the first base 41 so as to be rotatable about a predetermined drive axis D and driven to rotate, a follower 62 connected to the first base 41 so as to be rotatable about an axis parallel to the drive axis D, and an intermediate link 63 connected to each of the driver 61 and the follower 62 so as to be rotatable about an axis parallel to the drive axis D, and the second base 42 is connected to the intermediate link 63.

[0108] According to this configuration, the second base 42 moves relative to the first base 41 via the link mechanism 6, causing the hand 3 to move linearly in the translational direction Z relative to the robot arm 2. The linear movement by the link mechanism 6 is achieved by the Chebyshev link mechanism 60. The Chebyshev link mechanism 60 has a large linear movement stroke but is small overall in size. This allows the robot wrist 4 to be compact while increasing the stroke of the robot wrist 4 in the translational direction Z. Furthermore, the Chebyshev link mechanism 60 operates by rotation of the driving link 61. In other words, the drive source of the Chebyshev link mechanism 60 can be driven by a motor. For example, compared to drive by a cylinder or the like, drive by a motor provides high controllability. As a result, the positional accuracy of the hand 3 in the translational direction Z is improved.

[0109] [2] The robot wrist 4 described in [1] further includes a second actuator 52 that rotates the second base 42 around a pitch axis P that extends in a direction intersecting the linear direction Z, and a pitch transmission mechanism 8 that transmits the driving force of the second actuator 52 to the second base 42.

[0110] According to this configuration, the robot wrist 4 can rotate the hand 3 around the pitch axis P, in addition to linearly moving the hand 3 in the rectilinear direction Z. As a result, the hand 3 can be flexibly moved by the robot wrist 4.

[0111] [3] In the robot wrist 4 according to [1] or [2], the second base 42 is connected to the intermediate link 63 so as to be rotatable around the pitch axis P.

[0112] According to this configuration, during pitch movement of the robot wrist 4, the Chebyshev link mechanism 60 does not rotate about the pitch axis P, but the second base 42 rotates about the pitch axis P relative to the intermediate link 63. This allows the weight of the members that rotate about the pitch axis P to be reduced, improving the controllability of the pitch movement of the robot wrist 4.

[0113] [4] In the robot wrist 4 according to any one of [1] to [3], the pitch transmission mechanism 8 includes a four-bar link mechanism 80.

[0114] According to this configuration, the second base 42 is rotated around the pitch axis P via the four-bar link mechanism 80. Compared to a configuration in which the second base 42 is rotated via a cylinder or the like, the configuration for pitching the robot wrist 4 can be made smaller.

[0115] [5] In the robot wrist (4) according to any one of [1] to [4], the intermediate link (63) functions as a link included in the four-link mechanism (80).

[0116] According to this configuration, the second base 42 is connected to the intermediate link 63, and therefore the intermediate link 63 can be used as a node of the four-bar link mechanism 80 that rotates the second base 42 about the pitch axis P. By using the intermediate link 63 as a node of the four-bar link mechanism 80, the four-bar link mechanism 80 can be simplified.

[0117] [6] In the robot wrist 4 described in any one of [1] to [5], the four-bar link mechanism 80 is a parallel link mechanism including: a first fixed joint 83 which is the intermediate joint of the Chebyshev link mechanism 60; a first driver 84 which is connected to the first fixed joint 83 so as to be rotatable around an axis parallel to the pitch axis P; a first follower 85 which is connected to the first fixed joint 83 so as to be rotatable around an axis parallel to the pitch axis P and which is fixed to the second base 42; and a first intermediate joint 86 which is connected to each of the first driver 84 and the first follower 85 so as to be rotatable around an axis parallel to the pitch axis P, and the attitude of the first driver 84 is maintained during operation of the Chebyshev link mechanism 60.

[0118] According to this configuration, the intermediate link 63 of the Chebyshev link mechanism 60 also functions as the first fixed link 83 of the four-bar link mechanism 80. Therefore, when the Chebyshev link mechanism 60 operates, the four-bar link mechanism 80 also operates. Because the four-bar link mechanism 80 is a parallel link mechanism, the angle of the opposing links remains the same even when the four-bar link mechanism 80 operates. If the orientation of the first driver link 84 is maintained during operation of the Chebyshev link mechanism 60, the orientation of the first follower link 85 opposing the first driver link 84, i.e., the angle of the second base 42, is maintained. As a result, even when the Chebyshev link mechanism 60 and the four-bar link mechanism 80 share some of their links, the hand 3 can be moved in the translatory direction Z without changing the pitch angle of the hand 3.

[0119] [7] In the robot wrist 4 described in any one of [1] to [6], the four-bar link mechanism 80 includes a first four-bar link mechanism 81 connected to the second base 42, and a second four-bar link mechanism 82 connected to the first four-bar link mechanism 81 and driven by the second actuator 52.

[0120] According to this configuration, the driving force of the second actuator 52 is transmitted to the second base 42 via the first four-bar link mechanism 81 and the second four-bar link mechanism 82. The four-bar link mechanism 80 includes two four-bar link mechanisms, the first four-bar link mechanism 81 and the second four-bar link mechanism 82, and therefore a relatively flexible arrangement of the link mechanisms can be realized.

[0121] [8] In the robot wrist 4 described in any one of [1] to [7], the intermediate link 63 functions as a link included in the first four-link mechanism 81, and the driven link 62 functions as a link included in the second four-link mechanism 82.

[0122] According to this configuration, the intermediate link 63 is used as a node of the first four-link mechanism 81 and the driven link 62 is used as a node of the second four-link mechanism 82, thereby simplifying the four-link mechanism 80.

[0123] [9] In the robot wrist 4 described in any one of [1] to [8], the first four-bar link mechanism 81 includes a first fixed joint 83 that is the intermediate joint 63 of the Chebyshev link mechanism 60, a first driver 84 connected to the first fixed joint 83 rotatably around an axis parallel to the pitch axis P, a first follower 85 connected to the first fixed joint 83 rotatably around an axis parallel to the pitch axis P, and a first intermediate joint 86 connected to each of the first driver 84 and the first follower 85 rotatably around an axis parallel to the pitch axis P, and the second four-bar link mechanism 82 includes a second fixed joint 87 that is the follower 62 of the Chebyshev link mechanism 60, and a first driver 84 connected to the first fixed joint 83 rotatably around an axis parallel to the pitch axis P. a second driver 88 connected to the second fixed link 87 rotatably about an axis parallel to the pitch axis P; a second follower 89 connected to the second fixed link 87 rotatably about an axis parallel to the pitch axis P; and a second intermediate link 810 connected to each of the second driver and the second follower 84 rotatably about an axis parallel to the pitch axis P, wherein the second driver 88 is rotationally driven by the second actuator 52, the second follower 89 and the first driver 84 are connected by a connecting link 811, and the length of the driver 61 of the Chebyshev linkage 60 is longer than or equal to the length of any of the first driver 84, the first follower 85, and the second follower 89.

[0124] This configuration allows the robot wrist 4 to be compactly deformed in the translational direction Z. Specifically, the Chebyshev link mechanism 60 operates by rotation of the driver 61. The driver 61 is in a state of being most protruding in the translational direction Z when it faces the opposite side of the follower 62 in the translational direction Z, i.e., facing backward. Each of the first driver 84, the first follower 85, and the second follower 89 may also be in a state of facing backward in the translational direction Z. The length of the driver 61 is longer than or equal to the length of each of the first driver 84, the first follower 85, and the second follower 89. Therefore, even when each of the first driver 84, the first follower 85, and the second follower 89 is in a state of being most protruding in the translational direction Z, it only protrudes to approximately the same extent as the driver 61 in a state of being most protruding in the translational direction Z. In other words, it is possible to prevent any of the first driver 84, the first follower 85, and the second follower 89 from protruding in the linear direction Z beyond the range of movement of the driver 61. This makes it possible to prevent the dimension of the robot wrist 4 on the backward side in the linear direction Z from expanding beyond the range of movement of the driver 61.

[0125]

[10] In the robot wrist 4 described in any one of [1] to [9], the first four-bar link mechanism 81 includes a first fixed joint 83 that is the intermediate joint 63 of the Chebyshev link mechanism 60, a first driver 84 connected to the first fixed joint 83 rotatably around an axis parallel to the pitch axis P, a first follower 85 connected to the first fixed joint 83 rotatably around an axis parallel to the pitch axis P, and a first intermediate joint 86 connected to each of the first driver 84 and the first follower 85 rotatably around an axis parallel to the pitch axis P, and the second four-bar link mechanism 82 includes a second fixed joint that is the follower of the Chebyshev link mechanism 60. a second driver 88 connected to the second fixed link 87 so as to be rotatable about an axis parallel to the pitch axis P; a second follower 89 connected to the second fixed link 87 so as to be rotatable about an axis parallel to the pitch axis P; and a second intermediate link 810 connected to each of the second driver 88 and the second follower 89 so as to be rotatable about an axis parallel to the pitch axis P, wherein a shaft 812 that is rotationally driven by the second actuator 52 is connected to the second driver 88, and the second intermediate link 810 is curved to avoid interference with the shaft 812 when it approaches the shaft 812 in conjunction with the second driver 88.

[0126] This configuration increases the range of movement of the four-bar linkage mechanism 80, thereby increasing the range of pitch movement of the robot wrist 4. Specifically, in the first four-bar linkage mechanism 81 and the second four-bar linkage mechanism 82, when viewed in the direction of the rotation axis of the second driver link 88, a situation may occur in which one of the links approaches or overlaps with another joint. For example, the second intermediate link 810 may approach a joint including the rotation axis of the second driver link 88. A shaft 812 is connected to the second driver link 88. The second driver link 88 is rotationally driven by the second actuator 52 via the shaft 812. Therefore, the second intermediate link 810 may approach the shaft 812. The second intermediate link 810 is curved to avoid interference with the shaft 812. In the example described above, the second intermediate link 810 has a curved portion 810a that curves inward toward the side opposite the shaft 812. The curvature of the second intermediate link 810 makes it less likely that the second intermediate link 810 will interfere with the shaft 812. As a result, the range of motion of the second intermediate link 810 is increased, and the range of pitch motion of the robot wrist 4 is also increased.

[0127]

[11] The robot wrist 4 described in any one of [1] to

[10] further comprises a fourth actuator 54 that rotates the hand 3 around a predetermined yaw axis Y, and a yaw transmission mechanism 79 that transmits the driving force of the fourth actuator 54, wherein the second base 42 has a rotating body 46 that is rotatable around the yaw axis Y and to which the hand 3 is attached, and the yaw transmission mechanism 79 transmits the driving force of the fourth actuator 54 to the rotating body 46.

[0128] With this configuration, the robot wrist 4 can not only move the hand 3 linearly in the rectilinear direction Z, but also rotate the hand 3 around the yaw axis Y. As a result, the robot wrist 4 can flexibly move the hand 3.

[0129]

[12] The robot wrist 4 described in any one of [1] to

[11] further includes a third actuator 53 that rotates the second base 42 around a pitch axis P extending in a direction intersecting the linear direction Z and a roll axis R extending in a direction intersecting both the linear direction Z, and the link mechanism 6 is connected to the first base 41 so as to be rotatable around the roll axis R.

[0130] With this configuration, the robot wrist 4 can rotate the hand 3 about the roll axis R in addition to linearly moving the hand 3 in the translatory direction Z. As a result, the robot wrist 4 can flexibly move the hand 3. Furthermore, in addition to the hand 3, the link mechanism 6 also rotates about the roll axis R. In other words, the orientation of the translatory direction Z rotates about the roll axis R. As a result, the orientation of the linear movement of the hand 3 can be changed about the roll axis R.

[0131]

[13] In the robot wrist 4 described in any one of [1] to

[12] , the link mechanism 6 includes a pair of a first link mechanism 6A and a second link mechanism 6B arranged to face each other, and each of the first link mechanism 6A and the second link mechanism 6B movably connects the second base 42 to the first base 41 and includes the Chebyshev link mechanism 60, and the intermediate joint 63 of the first link mechanism 6A and the intermediate joint 63 of the second link mechanism 6B are connected to each other.

[0132] This configuration improves the support rigidity of the hand 3. More specifically, the second base 42 is supported by two link mechanisms, the first link mechanism 6A and the second link mechanism 6B, thereby improving the support rigidity of the second base 42. Furthermore, the first link mechanism 6A and the second link mechanism 6B face each other, and the intermediate link 63 of the first link mechanism 6A and the intermediate link 63 of the second link mechanism 6B are connected to each other. This improves the rigidity of the first link mechanism 6A and the second link mechanism 6B. As a result, the support rigidity of the second base 42 is also improved.

[0133]

[14] In the robot wrist 4 described in any one of [1] to

[13] , the first actuator 51 is disposed between the first link mechanism 6A and the second link mechanism 6B.

[0134] According to this configuration, the first actuator 51 is positioned between the first link mechanism 6A and the second link mechanism 6B, so that the size of the robot wrist 4 in the opposing direction between the first link mechanism 6A and the second link mechanism 6B can be made compact.

[0135]

[15] In the robot wrist 4 described in any one of [1] to

[14] , the driving link 61 of the first link mechanism 6A is arranged inward of the intermediate link 63 of the first link mechanism 6A in the opposing direction between the first link mechanism 6A and the second link mechanism 6B, and the driving link 61 of the second link mechanism 6B is arranged inward of the intermediate link 63 of the second link mechanism 6B in the opposing direction between the first link mechanism 6A and the second link mechanism 6B.

[0136] With this configuration, the operating range of the two intermediate links 63 can be expanded while the first actuator 51 is disposed between the first link mechanism 6A and the second link mechanism 6B. Specifically, since the first actuator 51 is disposed between the first link mechanism 6A and the second link mechanism 6B, the first actuator 51 and its transmission mechanism, etc. are disposed between the driver 61 of the first link mechanism 6A and the driver 61 of the second link mechanism 6B. If the driver 63 of the first link mechanism 6A and the driver 61 of the second link mechanism 6B were disposed inside the two driver links 61, there is a risk that the two intermediate links 63 would interfere with the first actuator 51 and its transmission mechanism, etc. On the other hand, by disposing the two intermediate links 63 outside the two driver links 61, the two intermediate links 63 can operate without interfering with the first actuator 51 and its transmission mechanism, etc.

[0137]

[16] In the robot wrist 4 described in any one of [1] to

[15] , the joint 64a connecting the driving link 61 and the intermediate link 63 in the first link mechanism 6A and the joint 64a connecting the driving link 61 and the intermediate link 63 in the second link mechanism 6B are connected to each other.

[0138] According to this configuration, by connecting the joint 64a of the first link mechanism 6A and the joint 64a of the second link mechanism 6B, it is possible to simultaneously connect the two prime mover links 61 and the two intermediate links 63. Furthermore, since the two intermediate links 63 are connected, the rigidity of the intermediate links 63 is improved, and as a result, the supporting rigidity of the hand 3 by the link mechanism 6 is improved.

[0139]

[17] The robot wrist 4 according to any one of [1] to

[16] further includes a second actuator 52 that rotates the second base 42 around a pitch axis P that extends in a direction intersecting the linear direction Z, and a pitch transmission mechanism 8 that transmits the driving force of the second actuator 52 to the second base 42, wherein the second base 42 is connected to the intermediate link 63 so as to be rotatable around the pitch axis P, and the pitch transmission mechanism 8 includes a first four-joint link mechanism 81 connected to the second base 42, and a second four-joint link mechanism 82 that is connected to the first four-joint link mechanism 81 and driven by the second actuator 52. The intermediate link 63 functions as a first fixed link 83 included in the first four-bar link mechanism 81, and the driven link 62 functions as a second fixed link 87 included in the second four-bar link mechanism 82, the first four-bar link mechanism 81 includes a first intermediate link 86 arranged in a position opposite the first fixed link 83, and the second four-bar link mechanism 82 includes a second intermediate link 810 arranged in a position opposite the second fixed link 87, and the first intermediate link 86 and the second intermediate link 810 are arranged in the same plane perpendicular to the opposing direction of the first link mechanism 6A and the second link mechanism 6B.

[0140] With this configuration, the first intermediate link 86 is included in the first four-bar linkage 81, and the second intermediate link 810 is included in the second four-bar linkage 82. Therefore, the first intermediate link 86 and the second intermediate link 810 hardly overlap in the facing direction. Even if the first intermediate link 86 and the second intermediate link 810 are arranged in the same plane perpendicular to the facing direction, the first intermediate link 86 and the second intermediate link 810 hardly interfere with each other. By arranging the first intermediate link 86 and the second intermediate link 810 in the same plane, the size of the four-bar linkage 80 in the facing direction can be reduced.

Claims

1. A robot wrist comprising: a first base attached to a robot arm; a second base to which a hand is attached; a link mechanism movably connecting the second base to the first base; and a first actuator for driving the link mechanism, wherein the link mechanism includes a Chebyshev link mechanism connecting the second base to the first base so as to be linearly movably in a predetermined rectilinear direction, the Chebyshev link mechanism having a driver connected to the first base rotatably about a predetermined drive axis and driven to rotate, a follower connected to the first base rotatably about an axis parallel to the drive axis, and an intermediate joint connected to each of the driver and follower rotatably about an axis parallel to the drive axis, and the second base is connected to the intermediate joint.

2. A robot wrist as described in claim 1, further comprising: a second actuator that rotates the second base around a pitch axis extending in a direction intersecting the linear direction; and a pitch transmission mechanism that transmits the driving force of the second actuator to the second base.

3. A robot wrist according to claim 2, wherein the second base is connected to the intermediate joint so as to be rotatable about the pitch axis.

4. A robot wrist according to claim 3, wherein the pitch transmission mechanism includes a four-bar link mechanism.

5. A robot wrist according to claim 4, wherein the intermediate link functions as a link included in the four-link mechanism.

6. A robot wrist as described in claim 5, wherein the four-bar link mechanism is a parallel link mechanism including a first fixed joint which is the intermediate joint of the Chebyshev link mechanism, a first driver connected to the first fixed joint rotatably about an axis parallel to the pitch axis, a first follower connected to the first fixed joint rotatably about an axis parallel to the pitch axis and fixed to the second base, and a first intermediate joint connected to each of the first driver and first follower rotatably about an axis parallel to the pitch axis, and the attitude of the first driver is maintained during operation of the Chebyshev link mechanism.

7. A robot wrist as described in claim 5, wherein the four-bar linkage includes a first four-bar linkage connected to the second base, and a second four-bar linkage connected to the first four-bar linkage and driven by the second actuator.

8. A robot wrist according to claim 7, wherein the intermediate link functions as a link included in the first four-bar linkage, and the driven link functions as a link included in the second four-bar linkage.

9. A robot wrist according to claim 8, wherein the first four-bar linkage includes a first fixed joint which is the intermediate joint of the Chebyshev linkage, a first driver connected to the first fixed joint rotatably about an axis parallel to the pitch axis, a first follower connected to the first fixed joint rotatably about an axis parallel to the pitch axis, and a first intermediate joint connected to each of the first driver and the first follower rotatably about an axis parallel to the pitch axis; and the second four-bar linkage includes a second fixed joint which is the follower of the Chebyshev linkage, a second driver connected to the second fixed joint rotatably about an axis parallel to the pitch axis, a second follower connected to the second fixed joint rotatably about an axis parallel to the pitch axis, and a second intermediate joint connected to each of the second driver and the second follower rotatably about an axis parallel to the pitch axis; A robot wrist, wherein the second driver is rotationally driven by the second actuator, the second follower and the first driver are connected by a connecting node, and a length of the driver of the Chebyshev linkage is longer than or equal to a length of any of the first driver, the first follower and the second follower.

10. A robot wrist according to claim 8, wherein the first four-bar linkage includes a first fixed joint which is the intermediate joint of the Chebyshev linkage, a first driver connected to the first fixed joint rotatably about an axis parallel to the pitch axis, a first follower connected to the first fixed joint rotatably about an axis parallel to the pitch axis, and a first intermediate joint connected to each of the first driver and the first follower rotatably about an axis parallel to the pitch axis; and the second four-bar linkage includes a second fixed joint which is the follower of the Chebyshev linkage, a second driver connected to the second fixed joint rotatably about an axis parallel to the pitch axis, a second follower connected to the second fixed joint rotatably about an axis parallel to the pitch axis, and a second intermediate joint connected to each of the second driver and the second follower rotatably about an axis parallel to the pitch axis; A robot wrist having a shaft connected to the second drive link and rotated by the second actuator, and a second intermediate link curved to avoid interference with the shaft when the second intermediate link approaches the shaft in conjunction with the second drive link.

11. A robot wrist as claimed in any one of claims 1 to 10, further comprising: a fourth actuator for rotating the hand around a predetermined yaw axis; and a yaw transmission mechanism for transmitting the driving force of the fourth actuator, wherein the second base has a rotating body rotatable around the yaw axis and to which the hand is attached, and the yaw transmission mechanism transmits the driving force of the fourth actuator to the rotating body.

12. A robot wrist as claimed in any one of claims 1 to 10, further comprising a third actuator for rotating the second base around a roll axis extending in a direction intersecting both the linear direction and a pitch axis extending in a direction intersecting both the linear direction, and the link mechanism is connected to the first base so as to be rotatable around the roll axis.

13. A robot wrist as described in claim 1, wherein the link mechanism includes a pair of first and second link mechanisms arranged to face each other, each of the first and second link mechanisms movably connecting the second base to the first base and including a Chebyshev link mechanism, and the intermediate joint of the first link mechanism and the intermediate joint of the second link mechanism are connected to each other.

14. A robot wrist according to claim 13, wherein the first actuator is disposed between the first link mechanism and the second link mechanism.

15. A robot wrist as described in claim 13 or 14, wherein the driving joint of the first link mechanism is positioned inward of the intermediate joint of the first link mechanism in the direction of opposition between the first link mechanism and the second link mechanism, and the driving joint of the second link mechanism is positioned inward of the intermediate joint of the second link mechanism in the direction of opposition between the first link mechanism and the second link mechanism.

16. A robot wrist as claimed in claim 13 or 14, wherein a joint connecting the driving joint and the intermediate joint in the first link mechanism and a joint connecting the driving joint and the intermediate joint in the second link mechanism are connected to each other.

17. A robot wrist according to claim 13 or 14, further comprising a second actuator for rotating the second base about a pitch axis extending in a direction intersecting the linear direction, and a pitch transmission mechanism for transmitting the driving force of the second actuator to the second base, wherein the second base is connected to the intermediate joint so as to be rotatable about the pitch axis, and the pitch transmission mechanism includes a first four-bar link mechanism connected to the second base, and a second four-bar link mechanism connected to the first four-bar link mechanism and driven by the second actuator, wherein the intermediate joint functions as a first fixed joint included in the first four-bar link mechanism, and the driven joint functions as a second fixed joint included in the second four-bar link mechanism, the first four-bar link mechanism includes a first intermediate joint located opposite the first fixed joint, and the second four-bar link mechanism includes a second intermediate joint located opposite the second fixed joint, A robot wrist in which the first intermediate link and the second intermediate link are arranged in the same plane perpendicular to the opposing direction of the first link mechanism and the second link mechanism.

Images