Link mechanism

Abstract

To increase a torque and a maximum joint angle of a link without increasing thrust of a direct-acting actuator and a movable width of a driving mechanism.SOLUTION: A link mechanism 3 includes a plurality of links 4 connected to each other in series through a joint 5, and a first driving mechanism 6 for driving the plurality of links 4. The first driving mechanism 6 includes at least one locker 8 pivoted to the link 4, a first actuator 7 for driving the plurality of links 4, and a plurality of rods 9 for connecting the link 4, the locker 8 and the first actuator 7 in series. A base end 10 of the at least one locker 8 is offset from the joint 5 in the corresponding link 4.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a link mechanism having a plurality of links directly connected via joints. [Background technology]

[0002] Conventionally, robot hand devices that imitate the human hand have been known with the aim of having robots perform a wide variety of tasks (for example, Patent Documents 1 and 2). These robot hands include a base portion that corresponds to the palm or back of a human hand, a finger mechanism (finger link mechanism) extending from one edge of the base portion, and an operating mechanism (drive mechanism) for operating the finger mechanism with power from a power source.

[0003] In the robot hand described in Patent Document 1, the drive mechanism includes a primary link mechanism, a secondary link mechanism, and a linear motion mechanism so that the finger mechanism can be operated around two axes by a single motor. The finger mechanism is driven by the motor via these mechanisms to change from an extended state to a bent state or from a bent state to an extended state.

[0004] The robot hand described in Patent Document 2 includes multiple finger mechanisms and a single power source for driving these finger mechanisms. The actuation mechanism is configured so that the single power source can actuate the multiple finger mechanisms with different bending amounts. Specifically, each actuation mechanism for actuating each finger mechanism includes two link arms, and some actuation mechanisms are configured so that the link ratio of both link arms differs from the link ratio of the other actuation mechanisms. Each finger mechanism is displaced between a straight position and a bent position relative to the base depending on the link ratio.

[0005] The finger link mechanisms of these robot hands are equipped with multiple (specifically, three) links (inter-joint members) and the same number of joints (joint members) as the links, and are connected to a base that forms the palm. As the palm is part of the robot's arm, it is connected to the main body (upper body) via multiple links (forearm, upper arm) and multiple joints (wrist, elbow, shoulder). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5430253 [Patent Document 2] Patent No. 6154698 Summary of the Invention [Problem to be solved by the invention]

[0007] Incidentally, when a human finger has three joints, starting from the fingertip, the sum of the maximum joint angles (flexion angles when the extended position is 0 degrees) of the first to third joints is approximately 270 degrees. In other words, the average maximum joint angle of each joint is approximately 90 degrees. However, in the finger link mechanisms of conventional robotic hands, the maximum joint angle of each joint is approximately 50-60 degrees, which is smaller than the average maximum joint angle of human finger joints. As a result, conventional robotic hands were unable to perform movements that required large joint angles, such as when a human hand grasps a thin rod.

[0008] Here, we consider a drive mechanism for achieving large joint angles. FIG. 9 shows a schematic configuration of a link mechanism 103 of a conventional robot 101, in which three links 4 (4A, 4B, 4C) are connected in series like human fingers. The link mechanism 103 has a configuration equivalent to a finger or arm, and includes, from its free end, a first link 4A, a second link 4B connected to the first link 4A via a first joint 5A, and a third link 4C connected to the second link 4B via a second joint 5B. Each joint is formed by a joint axis (pivot). The first link 4A extends relative to the second link 4B at a first joint angle θ1. The second link 4B extends relative to the third link 4C at a second joint angle θ2. The third link 4C extends relative to the fourth link 4D, which forms the base of the palm or upper body, at a third joint angle θ3. The joint angle θ is defined based on the position (0 degrees) where the free-end link 4 is extended relative to the base-end link 4. In other words, the joint angle θ is not based on the extension direction of the base-end link 4.

[0009] When the link mechanism 103 is operated like a human finger, it is desirable that the maximum joint angle of the first joint 5A to the third joint 5C be 90 degrees, and that the movable angle range of each link 4 be 0 to 90 degrees. There is also a desire to make the actuator that drives the link mechanism 103 as small as possible. For example, when a linear motion actuator 107 (FIG. 10) is used as the actuator for driving the link, the smaller the thrust (pushing / pulling force) of the linear motion actuator 107 required to generate a predetermined torque on the link 4, the better. To reduce the thrust of the linear motion actuator 107, the smaller the displacement of the joint angle θ relative to the displacement of the linear motion actuator 107, the better.

[0010] FIG. 10 is a schematic diagram of a robot 101 equipped with a parallel link mechanism 106 as a drive mechanism for operating the link mechanism 103. As shown in FIG. 10, the parallel link mechanism 106 includes a first rocker 108A pivotally supported at the second joint 5B and a first rod 9A that connects the free end of the first rocker 108A to the portion of the first link 4A other than the first joint 5A. The parallel link mechanism 106 also includes a second rocker 108B pivotally supported at the third joint 5C and a second rod 9B that connects the free end of the first rocker 108A to the free end of the second rocker 108B. The free end of the second rocker 108B is connected to a linear actuator 107 via a third rod 9C.

[0011] The first link 4A is actuated by linear displacement of the linear actuator 107. Specifically, when the linear actuator 107 is displaced to the left, the second rocker 108B, the first rocker 108A, and the first link 4A rotate clockwise (extension direction), and when the linear actuator 107 is displaced to the right, the second rocker 108B, the first rocker 108A, and the first link 4A rotate counterclockwise (bending direction). Note that the second link 4B and the third link 4C are held by the corresponding drive mechanisms and do not displace.

[0012] In order for the first joint 5A to the third joint 5C to be driven by the corresponding drive mechanisms and for the maximum joint angles of each of the first joint 5A to the third joint 5C to be 90 degrees, the second rocker 108B needs to rotate 270 degrees, which is the sum of the three maximum joint angles. However, since it is geometrically impossible to rotate the second rocker 108B 270 degrees using the illustrated slider crank mechanism, such an operation cannot be achieved using the parallel link mechanism 106.

[0013] Therefore, the speed-up mechanism will be considered. FIG. 11 is a schematic diagram of a robot 111 equipped with a speed-up four-bar mechanism 116. In FIG. 11, elements that are the same as or similar to elements of the robot 101 in FIG. 10 are assigned the same reference numerals. The lengths of the moment arms (the lengths from the base end to the free end of each rocker 108) are set so that the second rocker 108B amplifies the motion of the third rod 9C, and the first rocker 108A amplifies the motion of the second rod 9B. Therefore, in order to set the maximum joint angle of each of the first joint 5A to the third joint 5C to 90 degrees, the second rocker 108B does not need to rotate 270 degrees, which is the sum of the three maximum joint angles, and such a motion by the speed-up four-bar mechanism 116 is geometrically possible.

[0014] However, since the angular displacement of the first joint 5A relative to the displacement of the linear actuator 107 is large, the linear actuator 107 needs to generate a large thrust. Also, since the movement of the linear actuator 107 is accelerated by only two acceleration four-bar mechanisms 116, the length of the moment arm increases, and the movable range of the drive mechanism (the dimension indicated by the white arrow in the figure) also increases. Therefore, the robot 111 becomes heavier and larger.

[0015] In view of the above background, an object of the present invention is to provide a link mechanism that can increase the torque of the link and the maximum joint angle without increasing the output of the actuator or the movable range of the drive mechanism. [Means for solving the problem]

[0016] In order to solve the above problems, one aspect of the present invention is a link mechanism (3) comprising a plurality of links (4) connected in series via joints (5), and a drive mechanism (6) for driving the plurality of links, wherein the drive mechanism comprises at least one rocker (8) pivotally supported on the corresponding link, at least one actuator (7) for driving the plurality of links, and a plurality of rods (9) connecting the links, the rocker, and the actuator in series, and a base end (10) of at least one of the rockers is offset from the joint in the corresponding link.

[0017] According to this aspect, the base end of at least one rocker is offset from the joint of the corresponding link, so that the torque and maximum joint angle of the link can be increased without increasing the output of the actuator or the movable range of the drive mechanism.

[0018] In the above aspect, preferably, the plurality of links include a first link (4A), a second link (4B) connected to the first link via a first joint (5A), and a third link (4C) connected to the second link via a second joint (5B), and the drive mechanism includes a first drive mechanism (6) for driving the first link, and the first drive mechanism includes a first rocker (8A) having a base end (10A) pivotally supported on an intermediate portion of the second link, and a third link (4C) connected to the first joint (5B). The third link includes a first rod (9A) having one end (11A) pivoted to a part other than the third link and the other end (12A) pivoted to the free end side of the first rocker, a second rocker (8B) having a base end (10B) pivoted to the intermediate part of the third link, a second rod (9B) having one end (11B) pivoted to the free end side of the first rocker and the other end (12B) pivoted to the free end side of the second rocker, and a first actuator (7) that drives the second rocker to drive the first link.

[0019] According to this aspect, the base end of the first rocker is offset from the second joint toward the second link, and the base end of the second rocker is offset from the second joint toward the third link, which makes it possible to increase the torque of the first link and the sum of the maximum joint angle without increasing the thrust of the linear actuator and the movable range of the drive mechanism.

[0020] In the above aspect, preferably, the plurality of links further includes a fourth link (4D) connected to the third link via a third joint (5C), and the first drive mechanism further includes a third rocker (8C) having a base end (10C) pivoted to a part of the fourth link other than the third joint, and a third rod (9C) having one end (11C) pivoted to the free end side of the second rocker and the other end (12C) pivoted to the free end side of the third rocker, and the first actuator drives the second rocker via the third rocker.

[0021] According to this aspect, the base end of the third rocker is offset from the third joint toward the fourth link, which makes it possible to increase the torque of the first link and the sum of the maximum joint angles including the third joint in the first drive mechanism including the third joint without increasing the thrust of the linear actuator and the movable range of the drive mechanism.

[0022] In the above aspect, preferably, the first drive mechanism further comprises a fourth rod (9D) having one end (11D) pivotally supported on the free end side of the third rocker, and the first actuator is a linear actuator pivotally supporting the other end of the fourth rod.

[0023] According to this aspect, even if the output of the drive source of the first actuator is small, the torque of the first link can be increased.

[0024] In the above aspect, preferably, the drive mechanism further includes a second drive mechanism (20) for driving the second link, and the second drive mechanism comprises a fourth rocker (8D) having a base end (10D) pivoted to the third link, a fifth rod (9E) having one end (11E) pivoted to a part of the second link other than the second joint and the other end (12E) pivoted to the free end side of the fourth rocker, and a second actuator (27) that drives the fourth rocker to drive the second link, and the first drive mechanism and the second drive mechanism are arranged in parallel and cooperate to form a two-row parallel mechanism that drives the second link.

[0025] According to this aspect, when the second link is driven, the driving force of the first actuator acts on the second link in addition to the driving force of the second actuator. Therefore, it is possible to reduce the output of the second actuator while ensuring the driving force necessary to drive the second link. As a result, it is possible to reduce the size of the second actuator.

[0026] In the above aspect, preferably, the second drive mechanism further includes a sixth rod (9F) having one end (11F) pivotally supported on the free end side of the fourth rocker, and the second actuator is a linear actuator pivotally supporting the other end (12F) of the sixth rod.

[0027] In the above embodiment, the drive mechanism further includes a third drive mechanism (30) for driving the third link, and the third drive mechanism comprises a seventh rod (9G) having one end (11G) pivoted to a part of the third link other than the third joint, and a third actuator (37) consisting of a linear actuator pivoting the other end (12G) of the seventh rod, and the third drive mechanism, the first drive mechanism, and the second drive mechanism are arranged in parallel and cooperate to form a three-row parallel mechanism that drives the third link.

[0028] According to this aspect, when the third link is driven, the driving forces of the first and second actuators act on the third link in addition to the driving force of the third actuator. Therefore, it is possible to reduce the output of the third actuator while ensuring the driving force necessary to drive the third link. As a result, it is possible to reduce the size of the third actuator.

[0029] In the above aspect, preferably, the arm length (L) from the free end of the second rocker that pivotally supports the second rod to the base end (10B) of the second rocker is approximately equal to the offset dimension (D2) from the second joint to the base end of the second rocker.

[0030] When the base end of the second rocker is pivotally supported on the second joint, the free end of the second rocker does not approach the second joint even when the second rocker rotates. In contrast to such a case, according to this aspect, when the joint angles of the first joint and the second joint increase, the other end of the second rod approaches the second joint. This increases the operating range of the first actuator for driving the first joint, and makes it possible to increase the drive torque of the first joint.

[0031] In the above aspect, preferably, when the joint angles of the first joint and the second joint are maximum, the free end of the second rocker that pivotally supports the second rod substantially coincides with the second joint.

[0032] According to this aspect, the operating range of the first actuator for driving the first joint is increased, and the drive torque of the first joint can be increased.

[0033] In order to solve the above problem, another aspect of the present invention is a robot (1), which includes the link mechanism (3) of the above aspect and a control device (15) that controls the first actuator.

[0034] According to this aspect, a robot is provided that can increase the torque of the first link and the sum of the maximum joint angle without increasing the thrust of the linear motion actuator and the movable range of the drive mechanism.

[0035] According to the above aspects, it is possible to provide a torque transmission mechanism that can perform good bidirectional torque transmission, and a robot that includes the torque transmission mechanism. [Brief explanation of the drawings]

[0036] [Figure 1] FIG. 1 is a schematic diagram illustrating a main part of a robot including a first drive mechanism according to an embodiment; [Figure 2] Control device configuration diagram [Figure 3] FIG. 1 is an exploded perspective view of a robot according to an embodiment; [Figure 4] Diagram of the robot's first drive mechanism [Figure 5] Diagram of the robot's second drive mechanism [Figure 6] Diagram of the robot's third drive mechanism [Figure 7] A diagram showing the operating range of the first actuator [Figure 8] Illustrative diagram of the operating range of the first actuator [Figure 9] Schematic diagram of a conventional robot link mechanism [Figure 10] Schematic diagram of a robot equipped with a parallel link mechanism [Figure 11] Schematic diagram of a robot equipped with a speed-increasing four-link mechanism DETAILED DESCRIPTION OF THE INVENTION

[0037] Hereinafter, an embodiment of a link mechanism 3 according to the present invention and a robot 1 equipped with the link mechanism 3 will be described in detail with reference to the drawings.

[0038] The robot 1 according to the present invention is a so-called articulated robot, and the configuration of the main parts of the robot 1 according to the embodiment is shown in Fig. 1. However, the configuration shown in Fig. 1 is merely an example, and the present invention is not limited to this configuration.

[0039] As shown in FIG. 1, the robot 1 includes a base 2 corresponding to, for example, a human palm, and a link mechanism 3 displaceably connected to the base 2. The link mechanism 3 includes a plurality of links 4 including a first link 4A, a second link 4B, and a third link 4C connected in series in this order from the free end. The base 2 is supported at a portion corresponding to a human forearm or upper arm, and can be referred to as a fourth link 4D to which the third link 4C is connected. The first link 4A is connected to the second link 4B via a first joint 5A. The second link 4B is connected to the third link 4C via a second joint 5B. The third link 4C is connected to the fourth link 4D (base 2) via a third joint 5C.

[0040] Hereinafter, when the first link 4A, the second link 4B, the third link 4C, and the fourth link 4D are referred to collectively or individually without distinction, they may be simply referred to as links 4. Furthermore, when the first joint 5A, the second joint 5B, and the third joint 5C are referred to collectively or individually without distinction, they may be simply referred to as joints 5. Each joint 5 is configured by a joint axis that forms a rotation axis.

[0041] The link mechanism 3 also includes a first drive mechanism 6 for driving the first link 4A. The first drive mechanism 6 includes a first actuator 7 as a drive device. The first actuator 7 is configured as a linear actuator that displaces linearly in a predetermined direction, and is provided on the base 2. However, the drive source of the first actuator 7 may be provided on the base 2, or may be provided on a portion of the robot 1 other than the base 2, for example, a portion corresponding to the forearm or upper arm that supports the base 2. The drive source of the first actuator 7 may be any of various motors that can rotate in both directions.

[0042] The first drive mechanism 6 is configured to connect the first actuator 7 and the first link 4A, and drives the first link 4A by transmitting the power of the first actuator 7 to the first link 4A. Specifically, the first drive mechanism 6 operates when bending or extending the first joint 5A, the second joint 5B, and the third joint 5C. When the second joint 5B and the third joint 5C are fixed by other mechanisms (a second drive mechanism 20 and a third drive mechanism 30, which will be described later), the first joint 5A is bent or extended by the operation of the first drive mechanism 6. When the other mechanisms bend or extend at least one of the second joint 5B and the third joint 5C, the first drive mechanism 6 operates in synchronization with the other mechanisms, and cooperates to drive at least one of the second joint 5B and the third joint 5C.

[0043] The first joint 5A, the second joint 5B, and the third joint 5C are set by the corresponding drive mechanisms so that the maximum value of each joint angle θ is approximately 90 degrees, and the total maximum joint angle of the three joints 5 is set to approximately 270 degrees.

[0044] The overall configuration of the robot 1 will be described later with reference to Figures 3 to 6. The link mechanism 3 and the first drive mechanism 6 will be described with reference to Figure 1, which shows a schematic diagram of the main parts of the robot 1. Please also refer to Figures 3 and 4 as necessary.

[0045] The first drive mechanism 6 includes a first rocker 8A, a second rocker 8B, and a third rocker 8C, each connected to a corresponding link 4, and a first rod 9A, a second rod 9B, a third rod 9C, and a fourth rod 9D, each forming a connecting member.

[0046] The first rocker 8A has a base end 10A pivoted to the intermediate portion of the second link 4B (the portion between the first joint 5A and the second joint 5B). The second rocker 8B has a base end 10B pivoted to the intermediate portion of the third link 4C (the portion between the second joint 5B and the third joint 5C). The third rocker 8C has a base end 10C pivoted to a portion of the fourth link 4D other than the third joint 5C.

[0047] The first rod 9A has one end 11A pivoted to a portion of the first link 4A other than the first joint 5A and the other end 12A pivoted to the free end side of the first rocker 8A. The second rod 9B has one end 11B pivoted to the free end side of the first rocker 8A and the other end 12B pivoted to the free end side of the second rocker 8B. The third rod 9C has one end 11C pivoted to the free end side of the second rocker 8B and the other end 12C pivoted to the free end side of the third rocker 8C. The fourth rod 9D has one end 11D pivoted to the free end side of the third rocker 8C, opposite the other end 12C of the third rod 9C, and the other end 12D pivoted to the first actuator 7.

[0048] The first actuator 7 drives the third rocker 8C via the fourth rod 9D, the third rocker 8C drives the second rocker 8B via the third rod 9C, and the second rocker 8B drives the first link 4A via the first rod 9A.

[0049] Hereinafter, when referring to the first rocker 8A, the second rocker 8B, the third rocker 8C, etc. collectively or when referring to one without distinction, they may be simply referred to as rocker 8. Also, when referring to the first rod 9A, the second rod 9B, the third rod 9C, the fourth rod 9D, etc. collectively or when referring to one without distinction, they may be simply referred to as rod 9.

[0050] The robot 1 is equipped with a control device 15 that controls the drive of the first actuator 7 in order to control the operation of the first link 4A. The control device 15 may be provided in a portion corresponding to the base body 2, the forearm, or the upper arm where the drive source of the first actuator 7 is provided. The control device 15 controls the thrust (pushing / pulling force) of the first actuator 7.

[0051] 2, the control device 15 is configured as a so-called microcomputer that includes a processor 16 configured by a central processing unit (CPU) or the like, a storage device 17 such as an HDD or SSD, and a memory 18 configured by RAM, ROM, etc. The control device 15 is configured so that the processor 16 reads necessary data and software from the storage device 17 and executes predetermined arithmetic processing in accordance with the software.

[0052] The robot 1 is configured in this manner. As shown in FIG. 1, the base end 10A of the first rocker 8A is offset by a first dimension D1 from the second joint 5B toward the second link 4B. Furthermore, the base end 10B of the second rocker 8B is offset by a second dimension D2 from the second joint 5B toward the third link 4C. This makes it possible to increase the torque and maximum joint angle of the first link 4A and the sum of the maximum joint angles of the links 4 without increasing the thrust of the first actuator 7 or the movable range of the first drive mechanism 6 (the dimension in the direction perpendicular to the extension direction of the link 4).

[0053] Furthermore, the base end 10C of the third rocker 8C is offset by a third dimension D3 from the third joint 5C toward the base 2 forming the fourth link 4D. This makes it possible to increase the torque of the first link 4A and the sum of the maximum joint angles including the third joint 5C in the first drive mechanism 6 including the third joint 5C without increasing the thrust of the linear actuator and the movable range of the drive mechanism.

[0054] In this embodiment, the first actuator 7 that drives the first drive mechanism 6 is configured as a linear actuator, and the free end side of the third rocker 8C is connected to the first actuator 7 by the fourth rod 9D. This makes it possible to increase the torque of the first link 4A even if the output of the drive source of the first actuator 7 is small.

[0055] Fig. 3 is an exploded perspective view of the robot 1 including the above configuration. As shown in Fig. 3, in addition to the link mechanism 3 and first drive mechanism 6, the robot 1 is equipped with a second drive mechanism 20 for driving the second link 4B and a third drive mechanism 30 for driving the third link 4C.

[0056] The second drive mechanism 20 includes a second actuator 27 as a drive device. The third drive mechanism 30 includes a third actuator 37 as a drive device. The second actuator 27 and the third actuator 37 are configured as linear actuators that displace on a straight line parallel to the displacement direction of the first actuator 7, and are provided on the base 2. However, the drive source of the second actuator 27 and the drive source of the third actuator 37 may be provided on the base 2, or may be provided in a part of the robot 1 other than the base 2. The drive source of the second actuator 27 and the drive source of the third actuator 37 may be various motors that can rotate in both directions.

[0057] 4 is a configuration diagram of the first drive mechanism 6 of the robot 1. The configuration and operation of the first drive mechanism 6 are as described above, and therefore will not be described here.

[0058] FIG. 5 is a configuration diagram of the second drive mechanism 20 of the robot 1. As shown in FIGS. 3 and 5, the second drive mechanism 20 is configured to connect the second actuator 27 and the second link 4B and drives the second link 4B by transmitting the power of the second actuator 27 to the second link 4B. Specifically, the second drive mechanism 20 operates when bending or extending the second joint 5B and the third joint 5C. When the third joint 5C is fixed by the third drive mechanism 30, the second drive mechanism 20 operates to bend or extend the second joint 5B. When the second drive mechanism 20 bends or extends the second joint 5B, the first drive mechanism 6 operates in synchronization with the second drive mechanism 20 and cooperates to drive the second joint 5B.

[0059] The second drive mechanism 20 includes a fourth rocker 8D connected to the third joint 5C, and a fifth rod 9E and a sixth rod 9F each forming a connecting member.

[0060] In this embodiment, the fourth rocker 8D has a base end 10D pivotally supported on the third joint 5C, which is the connection between the third link 4C and the fourth link 4D.

[0061] The fifth rod 9E has one end 11E pivoted to a portion of the second link 4B other than the second joint 5B and the other end 12E pivoted to the free end side of the fourth rocker 8D. The sixth rod 9F has one end 11F pivoted to the free end side of the fourth rocker 8D, opposite to the other end 12E of the fifth rod 9E, and the other end 12F pivoted to the second actuator 27.

[0062] The second actuator 27 drives the fourth rocker 8D via the sixth rod 9F, and the fourth rocker 8D drives the second link 4B via the fifth rod 9E. The thrust (pushing / pulling force) of the second actuator 27 is controlled by the control device 15.

[0063] In this way, the first drive mechanism 6 and the second drive mechanism 20 are arranged in parallel and cooperate to form a two-row parallel mechanism that drives the second link 4B. Therefore, when driving the second link 4B, the drive force of the first actuator 7 acts on the second link 4B in addition to the drive force of the second actuator 27. Therefore, the output of the second actuator 27 can be reduced while ensuring the drive force necessary to drive the second link 4B, and the second actuator 27 can be made smaller.

[0064] In this embodiment, the second actuator 27 that drives the second drive mechanism 20 is configured as a linear actuator, and the sixth rod 9F connects the free end side of the fourth rocker 8D to the second actuator 27. This makes it possible to increase the torque of the second link 4B even if the output of the drive source of the second actuator 27 is small.

[0065] FIG. 6 is a configuration diagram of the third drive mechanism 30 of the robot 1. As shown in FIGS. 3 and 6, the third drive mechanism 30 is configured to connect the third actuator 37 and the third link 4C, and drives the third link 4C by transmitting the power of the third actuator 37 to the third link 4C. Specifically, the third drive mechanism 30 operates when bending or extending the third joint 5C. When the third drive mechanism 30 bends or extends the third joint 5C, the first drive mechanism 6 and the second drive mechanism 20 operate synchronously and cooperate to drive the third joint 5C.

[0066] The third drive mechanism 30 includes a seventh rod 9G. The seventh rod 9G has one end 11G pivotally supported on a portion of the third link 4C other than the third joint 5C, and the other end 12G pivotally supported on the third actuator 37.

[0067] The third actuator 37 drives the third link 4C via the seventh rod 9G. The thrust (pushing / pulling force) of the third actuator 37 is controlled by the control device 15.

[0068] In this way, the third drive mechanism 30, the first drive mechanism 6, and the second drive mechanism 20 are arranged in parallel and cooperate to form a three-row parallel mechanism that drives the third link 4C. Therefore, when driving the third link 4C, the drive forces of the first actuator 7 and the second actuator 27 act on the third link 4C in addition to the drive force of the third actuator 37. Therefore, the output of the third actuator 37 can be reduced while ensuring the drive force necessary to drive the third link 4C, and the third actuator 37 can be made smaller.

[0069] Next, the effects of the robot 1 configured as described above will be described. Figure 7 is a diagram showing the operating range of the first actuator 7. As shown in Figures 1 and 7, the first actuator 7 pushes and pulls the third rod 9C by rotationally driving the third rocker 8C. In order to maximize the pushing and pulling range of the third rod 9C, the rotation angle range of the third rocker 8C is set to be smaller than 180 degrees, and the operating range of the first actuator 7 is set accordingly.

[0070] As described above, the first actuator 7 not only operates when driving the first joint 5A, but also when driving the second joint 5B and the third joint 5C. When the link mechanism 3 is in a straight extended state, the first actuator 7 is located at the left end of its operating range as shown by the solid line, so that the third rod 9C is positioned at its most retracted position. When each joint 5 is bent to its maximum extent and the link mechanism 3 is in its most bent state, the first actuator 7 is located at the right end of its operating range as shown by the imaginary line, so that the third rod 9C is positioned at its most retracted position.

[0071] FIG. 8 is an explanatory diagram of the operating range of the first actuator 7. FIG. 8 shows the division of the operating range when the link mechanism 3 in the extended state is bent in the order of the third joint 5C, the second joint 5B, and the first joint 5A so that the joint angle θ is from 0 degrees to the maximum angle. When the link mechanism 3 is operated in this manner, the left part of the operating range is the operating range for driving the third joint 5C. The central part of the operating range is the operating range for driving the second joint 5B. The right part of the operating range is the operating range for driving the first joint 5A.

[0072] Although not shown, the operating range of the second actuator 27 is divided into two operating ranges: an operating range for driving the third joint 5C and an operating range for driving the second joint 5B. The entire operating range of the third actuator 37 is the operating range for driving the third joint 5C.

[0073] When driving the third joint 5C, the entire operating range of the third actuator 37, a partial area of ​​the operating range of the second actuator 27, and a partial area of ​​the operating range of the first actuator 7 are used as driving ranges. In other words, by providing the robot 1 with the above-described parallel mechanism, it is possible to increase the output torque of the third joint 5C, which is closest to the base body 2, without increasing the size of the drive source of each actuator to increase the output.

[0074] On the other hand, when driving the first joint 5A, only a part of the operating range of the first actuator 7 is used as the driving range. Therefore, the output torque of the first joint 5A is small.

[0075] Here, there is a relationship between the size of the motion range (stroke) and the torque of the joint 5 driven by that motion, such that the larger the stroke, the larger the torque. Therefore, in the first drive mechanism 6, to increase the torque of the first joint 5A, it is preferable to set the motion range for driving the first joint 5A large. In other words, it is preferable to set the motion range for driving the other joints 5 small.

[0076] In this embodiment, since the first drive mechanism 6 of the robot 1 is configured as described above, the operating range for driving the first joint 5A is larger than the operating range for the second joint 5B and the operating range for the third joint 5C, as shown in Fig. 8. This allows a large torque to be generated at the first joint 5A even if the robot 1 is equipped with a parallel mechanism.

[0077] To explain this in more detail with reference to Figure 1, the second dimension D2 (offset dimension of the second rocker 8B) and the arm length L of the second rocker 8B from the free end that pivots the second rod 9B of the second rocker 8B to the base end 10B of the second rocker 8B are set to be approximately equal, and other dimensions of the first drive mechanism 6 are also set so that the free end that pivots the second rod 9B of the second rocker 8B approaches the second joint 5B when each joint 5 is bent to its maximum.

[0078] With this setting, when the joint angle θ between the first joint 5A and the second joint 5B increases, the other end 12B of the second rod 9B approaches the second joint 5B. This increases the operating range of the first actuator 7 for driving the first joint 5A, and makes it possible to increase the drive torque of the first joint 5A.

[0079] Furthermore, when each joint 5 is bent to its maximum extent and the link mechanism 3 is in its most bent state (i.e., when the joint angle θ of the first joint 5A and the second joint 5B is maximum), it is even more preferable that the free end of the second rocker 8B that pivots the second rod 9B substantially coincides with the second joint 5B. This increases the operating range of the first actuator 7 for driving the first joint 5A, and the drive torque of the first joint 5A can be increased. Here, it is preferable that the free end of the second rocker 8B substantially coincides with the second joint 5B by at least partially overlapping the joints, and even more preferable that the joint axes of the two joints coincide with each other by at least partially overlapping.

[0080] Although the description of the specific embodiments has been completed above, the present invention is not limited to the above-described embodiments and modifications, and can be implemented in a wide variety of ways. For example, the specific configuration, arrangement, and quantity of each component and part can be changed as appropriate within the scope of the present invention. Furthermore, some or all of the configurations of the above-described embodiments may be combined with each other. Meanwhile, not all of the components shown in the above-described embodiments are necessarily required, and can be selected as appropriate. [Explanation of symbols]

[0081] 1:Robot 2: Base (4th link) 3: Link mechanism 4: Link 4A: First link 4B: Second link 4C: Third link 4D: 4th link 5: Joints 5A: First joint 5B: Second joint 5C: Third joint 6: First drive mechanism 7: First actuator 8: Locker 8A: Locker No. 1 8B: Second locker 8C: 3rd Locker 8D: 4th locker 9: Rod 9A: First rod 9B: Second rod 9C: Third rod 9D: 4th rod 9E: 5th Rod 9F: 6th Rod 9G: 7th rod 10A: Base end of first rocker 8A 10B: Base end of second rocker 8B 10C: Base end of third rocker 8C 10D: Base end of fourth rocker 8D 11A: One end of the first rod 9A 11B: One end of the second rod 9B 11C: One end of the third rod 9C 11D: One end of the fourth rod 9D 11E: One end of the fifth rod 9E 11F: One end of 6th rod 9F 11G: One end of the 7th rod 9G 12A: The other end of the first rod 9A 12B: The other end of the second rod 9B 12C: The other end of the third rod 9C 12D: The other end of the fourth rod 9D 12E: The other end of the fifth rod 9E 12F: The other end of the 6th rod 9F 12G: The other end of the 7th rod 9G 15: Control device 20: Second drive mechanism 27: Second actuator 30: Third drive mechanism 37: Third actuator D2: Second dimension (offset dimension of second rocker 8B) L: Arm length of second rocker 8B θ: joint angle θ1: First joint angle θ2: Second joint angle θ3: Third joint angle

Claims

1. A link mechanism comprising: A plurality of links directly connected via joints; a drive mechanism for driving the plurality of links, The drive mechanism at least one rocker pivotally supported on a corresponding said link; at least one actuator for driving a plurality of said links; a plurality of rods connecting the link, the rocker, and the actuator in series, A linkage in which a base end of at least one of the rockers is offset from the joint of the corresponding link.

2. the plurality of links include a first link, a second link connected to the first link via a first joint, and a third link connected to the second link via a second joint; the drive mechanism includes a first drive mechanism for driving the first link; The first drive mechanism a first rocker having a base end pivotally supported on an intermediate portion of the second link; a first rod having one end pivotally supported on a portion of the first link other than the first joint and the other end pivotally supported on a free end side of the first rocker; a second rocker having a base end pivotally supported on an intermediate portion of the third link; a second rod having one end pivotally supported on the free end side of the first rocker and the other end pivotally supported on the free end side of the second rocker; 2. The linkage mechanism according to claim 1, further comprising: a first actuator that drives the second rocker to drive the first link.

3. the plurality of links further includes a fourth link connected to the third link via a third joint; The first drive mechanism a third rocker having a base end pivotally supported on a portion of the fourth link other than the third joint; a third rod having one end pivotally supported on the free end side of the second rocker and the other end pivotally supported on the free end side of the third rocker, 3. The linkage according to claim 2, wherein the first actuator drives the second rocker through the third rocker.

4. the first drive mechanism further includes a fourth rod having one end pivotally supported on the free end side of the third rocker, 4. The link mechanism according to claim 3, wherein the first actuator is a linear actuator that pivotally supports the other end of the fourth rod.

5. the drive mechanism further includes a second drive mechanism for driving the second link; The second drive mechanism a fourth rocker having a base end pivotally supported on the third link; a fifth rod having one end pivotally supported on a portion of the second link other than the second joint and the other end pivotally supported on the free end side of the fourth rocker; a second actuator that drives the fourth rocker to drive the second link, The link mechanism according to claim 3 , wherein the first drive mechanism and the second drive mechanism are arranged in parallel and cooperate to form a two-row parallel mechanism that drives the second link.

6. the second drive mechanism further includes a sixth rod having one end pivotally supported on the free end side of the fourth rocker, 6. The link mechanism according to claim 5, wherein the second actuator is a linear actuator that pivotally supports the other end of the sixth rod.

7. the drive mechanism further includes a third drive mechanism for driving the third link; The third drive mechanism a seventh rod having one end pivotally supported on a portion of the third link other than the third joint; a third actuator comprising a linear actuator pivotally supporting the other end of the seventh rod, 6. The link mechanism according to claim 5, wherein the third drive mechanism, the first drive mechanism, and the second drive mechanism are arranged in parallel and cooperate to form a three-row parallel mechanism that drives the third link.

8. 3. The link mechanism according to claim 2, wherein an arm length from a free end of the second rocker that pivotally supports the second rod to a base end of the second rocker is approximately equal to an offset dimension from the second joint to the base end of the second rocker.

9. 9. The link mechanism according to claim 8, wherein when the joint angles of the first joint and the second joint are maximum, the free end of the second rocker that pivotally supports the second rod substantially coincides with the second joint.

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