JP2023021053A - Spherical link operation device - Google Patents

Abstract

To provide a spherical link operation device which can enhance a degree of freedom of an arrangement of a drive source.SOLUTION: A spherical link device comprises a spherical link mechanism, a plurality of string-shaped members, and a plurality of drive sources. The spherical link mechanism has a base end link hub, a tip link hub, and a plurality of links for connecting the base end link hub and the tip link hub. Each of the plurality of links includes a base end link member, a tip link member, and an intermediate link member. The base end link member is connected to the base end link hub so as to be rotatable around a first rotating shaft at one end of the base end link member. The tip link member is connected to the tip link hub so as to be rotatable around a second rotating shaft at one end of the tip link member. The intermediate link member is connected to the other end of the base end link member so as to be rotatable around a third rotating shaft at one end of the intermediate link member, and also connected to the other end of the tip link member so as to be rotatable around a fourth rotating shaft at the other end of the intermediate link member.SELECTED DRAWING: Figure 1

Description

The present invention relates to spherical link actuators.

Japanese Patent No. 6289973 (Patent Document 1) describes a link actuating device. The link actuating device described in Patent Document 1 has a spherical link mechanism and a plurality of posture changing actuators.

The spherical linkage has a proximal link hub, a distal link hub, and a plurality of links. A plurality of links connect the proximal link hub and the distal link hub. Each of the plurality of links has a proximal link member, a distal link member and an intermediate link member.

The proximal link member is connected to the proximal link hub at one end thereof so as to be rotatable around the first rotation axis. The tip link member is connected to the tip link hub at one end of the tip link member so as to be rotatable around the second rotation axis. The intermediate link member is connected at one end of the intermediate link member to the other end of the proximal link member so as to be rotatable about the third rotation axis, and is rotatable at the other end of the intermediate link member about the fourth rotation axis. is connected to the other end of the tip link member.

The center axis of the base end link hub, the first rotation axis and the third rotation axis intersect at one point. This one point is defined as the center point of the first spherical link. The center axis of the tip link hub, the second rotation axis and the fourth rotation axis intersect at a point different from the center point of the first spherical link. This other point is set as the center point of the second spherical link. The proximal link hub moves on a spherical surface centered on the first spherical link center point. The tip link hub moves on a spherical surface centered on the second spherical link center point. That is, the spherical link mechanism is configured by combining two spherical link mechanisms.

In the link actuating device described in Patent Document 1, each of the plurality of posture changing actuators rotates the base end link member of each of the plurality of links around the first rotation axis, thereby moving the base end link hub of the tip link hub. The position and attitude with respect to is changed.

Japanese Patent No. 6289973

In the link actuating device described in Patent Document 1, in order to rotate the base end link member of each of the plurality of links around the first rotation axis, a plurality of posture changing actuators are arranged radially around the base end link hub. I can't help it. That is, in a plurality of link actuating devices, the arrangement of a plurality of posture changing actuators is greatly restricted.

The present invention has been made in view of the problems of the prior art as described above. More specifically, the present invention provides a spherical link actuation device capable of increasing the degree of freedom in arranging the drive source.

A spherical link actuator of the present invention includes a spherical link mechanism, a plurality of string members, and a plurality of drive sources. The spherical linkage has a proximal link hub, a distal link hub, and a plurality of links connecting the proximal and distal link hubs. Each of the plurality of links includes a proximal link member, a distal link member and an intermediate link member. The proximal link member is connected to the proximal link hub at one end thereof so as to be rotatable around the first rotation axis. The tip link member is connected to the tip link hub at one end of the tip link member so as to be rotatable around the second rotation axis. The intermediate link member is connected at one end of the intermediate link member to the other end of the base end link member so as to be rotatable around the third rotation axis, and is connected at the other end of the intermediate link member to the other end of the distal link member. 4 It is connected so as to be rotatable around the rotation axis. The center axis of the proximal link hub, the first rotation axis and the third rotation axis intersect at the first spherical link center point. The center axis of the tip link hub, the second rotation axis and the fourth rotation axis intersect at the second spherical link center point. The proximal link hub and the distal link hub respectively move on a first moving spherical surface centered on the first spherical link center point and on a second moving spherical surface centered on the second spherical link center point. Each of the plurality of string-like members is connected to each of the plurality of drive sources and the spherical link mechanism. The power of each of the plurality of drive sources is transmitted to the spherical link mechanism via each of the plurality of string members, thereby changing the position and attitude of the distal end link hub relative to the proximal end link hub.

In the spherical link actuator described above, each of the plurality of drive sources may adjust the tension applied to each of the plurality of string-like members, thereby changing the position and orientation of the distal link hub relative to the proximal link hub. .

In the spherical link actuation device described above, each of the plurality of string-like members may connect the intermediate link member of each of the plurality of links and each of the plurality of drive sources.

The spherical link actuator described above may further comprise a plurality of pulleys attached to the proximal link hub. Each of the plurality of pulleys may have a pulley and a pulley fixed shaft member and be attached to the proximal link hub by the pulley fixed shaft member. Each of the plurality of string members may be relayed by pulleys of each of the plurality of pulleys.

In the spherical link actuator described above, the pulley in each of the plurality of pulleys may be rotatable about the central axis of the pulley fixed shaft member with one rotational degree of freedom.

In the spherical link actuator described above, in each of the plurality of pulleys, the center axis of the pulley fixed shaft member may pass through the first spherical link center point.

The above spherical link actuator may further comprise a plurality of first pulleys and a plurality of second pulleys. Each of the plurality of string-like members may connect the tip link hub and each of the plurality of drive sources. Each of the plurality of first pulleys may have a first pulley and a first pulley fixed shaft member, and may be attached to the proximal link hub by the first pulley fixed shaft member. Each of the plurality of second pulleys may have a second pulley and a second pulley fixed shaft member, and may be attached to an intermediate link member of each of the plurality of links by the second pulley fixed shaft member. Each of the plurality of string-shaped members may be relayed by a first pulley of each of the plurality of first pulleys and a second pulley of each of the plurality of second pulleys.

In the spherical link actuator described above, in each of the plurality of first pulleys, the first pulley may be rotatable about the central axis of the first pulley fixed shaft member with one rotational degree of freedom. Each of the plurality of second pulleys may be non-rotatable with respect to each intermediate link member of the plurality of links.

In the spherical link actuation device described above, the second pulley of each of the plurality of second pulleys may be positioned outside the intermediate link member of each of the plurality of links.

In the spherical link actuation device described above, the second pulley of each of the plurality of second pulleys may be positioned inside the intermediate link member of each of the plurality of links.

In the spherical link actuator described above, each of the plurality of string-like members may connect the tip link hub or the tip link member of each of the plurality of links and each of the plurality of drive sources.

In the spherical link actuator described above, each of the plurality of drive sources may have a pulley. Each of the plurality of drive sources may adjust the tension applied to each of the plurality of string-like members by rotating a pulley to wind up or let out each of the plurality of string-like members.

The spherical link actuators described above may further comprise a plurality of sensors. Each of the plurality of sensors may be configured to be capable of detecting the winding amount or the feeding amount of each of the plurality of string members by the pulleys of the plurality of drive sources. In the spherical link actuator described above, the plurality of string members may be a plurality of wires, a plurality of threads, a plurality of chains or a plurality of belts.

The spherical link actuator described above may further comprise a plurality of tensioners. Each of the plurality of tensioners may be configured to be able to adjust the tension applied to each of the plurality of string members.

In the above spherical link actuator, each of the plurality of drive sources rotates the base end link member of each of the plurality of links around the first rotation axis via each of the plurality of string members, thereby The position and orientation of the hub may vary.

In the spherical link actuator described above, the plurality of cord-like members may be a plurality of annular timing belts. Each of the plurality of drive sources may have a timing pulley. A base end link member of each of the plurality of links and a timing pulley of each of the plurality of drive sources may be connected by each of a plurality of annular timing belts.

The spherical link actuation device described above may further include a plurality of pulleys and a plurality of drive converters. Each of the plurality of pulleys may have a first pulley and a pulley fixed shaft member and be attached to the proximal link hub by the pulley fixed shaft member. In each of the plurality of pulleys, the first pulley may be rotatable with one rotational degree of freedom around the central axis of the pulley fixed shaft member. Each of the plurality of drive conversion units includes a support portion, a second pulley attached to the support portion, a first gear that rotates together with the second pulley, and a second gear to which the rotational force of the first gear is transmitted. , and a gear fixing shaft member fixed to the second gear. Each of the plurality of string members may be relayed to the first pulley of each of the plurality of pulleys to connect the second pulley of each of the plurality of drive sources and each of the plurality of drive sources. The gear fixing shaft member of each of the plurality of drive conversion parts is fixed to one end of each tip link member of each of the plurality of links, and is connected to the tip link hub rotatably around the second rotation axis. good too. In each of the plurality of drive conversion parts, the support part may be rotatable around the second rotation axis independently from the gear fixing shaft member.

In the spherical link actuation device described above, the first pulley of each of the plurality of pulleys may be arranged on the same plane as the second pulley of each of the plurality of drive converting portions.

The spherical link actuator described above may further comprise a plurality of tension adjustment mechanisms. Each of the plurality of tension adjusting mechanisms is configured to be able to adjust the tension applied to each of the plurality of cord-like members between the first pulley of each of the plurality of pulleys and the second pulley of each of the plurality of drive sources. may be

In the spherical link actuator described above, each of the plurality of drive sources rotates the base end link member and the tip end link member of each of the plurality of links around the first rotation axis and the second rotation axis via each of the plurality of string members. They may be simultaneously rotated around the rotation axis. In each of the plurality of links, the rotation direction of the base end link member about the first rotation axis is opposite to the rotation direction of the tip link member about the second rotation axis, and the base end link member rotates about the first rotation axis. The amount of rotation may be the same as the amount of rotation of the tip link member about the second rotation axis.

In the spherical link actuator described above, each of the plurality of string-like members may be connected to the proximal link member and the distal link member after being relayed by the intermediate link member in each of the plurality of links.

According to the spherical link actuator of the present invention, it is possible to increase the degree of freedom in arranging the drive source.

1 is a perspective view of a spherical link actuator 100; FIG. 2 is a front view of the spherical link actuator 100; FIG. It is a perspective view of spherical link actuator 100A. It is a front view of spherical link actuator 100A. Fig. 10 is a perspective view of the spherical link actuator 100A when the bending angle of the distal end link hub 12 with respect to the proximal end link hub 11 is 90°; It is a perspective view of the spherical link actuator 100B. It is a front view of the spherical link actuator 100B. Fig. 10 is a perspective view of the spherical link actuator 100B showing the cord-like member 30 without omitting it entirely; It is a perspective view of spherical link actuator 100C. Fig. 10 is a perspective view of a pulley 50 included in the spherical link actuator 100C; It is a perspective view of spherical link actuator 100D. It is a front view of spherical link actuator 100D. It is a perspective view of spherical link actuator 100D concerning a modification. It is a perspective view of the spherical link actuator 100E. Fig. 10 is a perspective view of a drive converting portion 70 included in the spherical link actuation device 100E;

Details of embodiments of the present invention will be described with reference to the drawings. In the drawings below, the same or corresponding parts are denoted by the same reference numerals, and redundant description will not be repeated.

(First embodiment)
A spherical link actuation device (referred to as a "spherical link actuation device 100") according to the first embodiment will be described below.

<Structure of Spherical Link Actuator 100>
FIG. 1 is a perspective view of a spherical link actuator 100. FIG. FIG. 2 is a front view of the spherical link actuator 100. FIG. As shown in FIGS. 1 and 2 , the spherical link actuator 100 has a spherical link mechanism 10 , multiple drive sources 20 , and multiple cord-like members 30 .

The spherical link mechanism 10 has a proximal end link hub 11 , a distal end link hub 12 and a plurality of links 13 . The proximal end link hub 11 and the distal end link hub 12 are connected by a plurality of links 13 . Let the central axis of the base end link hub 11 be the first central axis. Let the central axis of the tip link hub 12 be the second central axis.

The number of multiple links 13 is, for example, three. However, the number of multiple links 13 may be two, or may be four or more. A case where the number of the plurality of links 13 is three will be described below as an example. The plurality of links 13 are arranged at regular intervals, for example. When a plurality of links 13 are arranged at regular intervals, calculations for the spherical link mechanism 10 are easy to perform. Note that the plurality of links 13 may not be arranged at regular intervals.

The link 13 has a proximal link member 13a, a distal link member 13b, and an intermediate link member 13c. The proximal end link member 13a and the distal end link member 13b are, for example, L-shaped. The intermediate link member 13c has, for example, an arc shape.

The proximal link member 13a is connected to the proximal link hub 11 at one end thereof so as to be rotatable around the first rotation axis. Friction associated with rotation of the proximal end link member 13a with respect to the proximal end link hub 11 may be reduced by a rotational resistance reduction member. This rotational resistance reduction member is, for example, a rolling bearing or a sliding bearing.

The tip link member 13b is rotatably connected to the tip link hub 12 at one end of the tip link member 13b about the second rotation axis. Friction due to rotation of the tip link member 13b with respect to the tip link hub 12 may be reduced by a rotational resistance reduction member. This rotational resistance reduction member is, for example, a rolling bearing or a sliding bearing.

One end of the intermediate link member 13c is connected to the other end of the base end link member 13a so as to be rotatable around the third rotation axis. The intermediate link member 13c is connected at the other end of the intermediate link member 13c to the other end of the tip link member 13b so as to be rotatable around the fourth rotation axis.

The friction associated with the rotation of the intermediate link member 13c with respect to the base end link member 13a and the friction associated with the rotation of the intermediate link member 13c with respect to the distal end link member 13b may be reduced by a rotational resistance reduction member. This rotational resistance reduction member is, for example, a rolling bearing or a sliding bearing.

The first central axis, the first rotation axis and the third rotation axis intersect at one point. This one point is defined as the center point of the first spherical link. The second center axis, the second rotation axis, and the fourth rotation axis intersect at a point other than the first spherical link center point. This other point is set as the center point of the second spherical link. The distance between the first spherical link center point and the second spherical link center point is constant regardless of the position and orientation of the distal end link hub 12 with respect to the proximal end link hub 11 .

The base end link hub 11 moves on a spherical surface centered on the first spherical link center point. This spherical surface is defined as the first moving spherical surface. The tip link hub 12 moves on a spherical surface centered on the second spherical link center point. This spherical surface is referred to as a second moving spherical surface. The spherical link mechanism 10 has a structure in which two spherical link mechanisms are combined.

A plane where the first moving spherical surface and the second moving spherical surface intersect is defined as an intermediate plane. The proximal end link hub 11 side of the spherical link mechanism 10 (the portion of the spherical link mechanism 10 that is closer to the proximal end link hub 11 than the intermediate plane) is the distal end link hub 12 side of the spherical link mechanism 10 (intermediate plane The part of the spherical link mechanism 10 on the tip link hub 12 side) always moves symmetrically.

The number of drive sources 20 is, for example, three. However, the number of drive sources 20 may be two, or may be four or more. A case in which the number of the plurality of drive sources 20 is three will be described below as an example.

The drive source 20 has a main body 21 (not shown in FIGS. 1 and 2) and a shaft 22 . The body portion 21 rotates the shaft body 22 around its central axis. The body portion 21 is housed inside the case 40 . The shaft 22 is outside the case 40 . The drive source 20 is, for example, a motor. The spherical link mechanism 10 is arranged on the case 40 .

The number of string members 30 is equal to the number of links 13 . Also, the number of string members 30 is equal to the number of drive sources 20 . The string member 30 connects the drive source 20 and the spherical link mechanism 10 . More specifically, the string member 30 connects the shaft 22 and the intermediate link member 13c. The string-like member 30 may connect the shaft 22 and the tip link hub 12 . The string-like member 30 may connect the shaft 22 and the proximal end link member 13a or the distal end link member 13b.

The string member 30 may connect the pulley attached to the shaft 22 to any one of the tip link hub 12, the base end link member 13a, the tip link member 13b, and the intermediate link member 13c. The string-like member 30 is, for example, a wire. However, the string-like member 30 may be a thread, a chain or a belt.

Each of the plurality of drive sources 20 transmits power to the spherical link mechanism 10 via each of the plurality of string members 30, thereby changing the position and posture of the distal end link hub 12 with respect to the proximal end link hub 11. . More specifically, each of the plurality of drive sources 20 adjusts the tension applied to each of the plurality of string members 30 . As a result, the position at which the tension applied to each of the string-like members 30 is balanced changes, and the position and attitude of the distal end link hub 12 with respect to the proximal end link hub 11 are changed.

The string-like member 30 is wound around the shaft 22 as the main body 21 rotates the shaft 22 . The string-like member 30 is drawn out from the shaft body 22 when the main body part 21 reversely rotates the rotating shaft. Thereby, the tension applied to the string-like member 30 is adjusted.

The spherical link actuator 100 may have multiple sensors. Each of the plurality of sensors is configured to be able to detect the winding amount and the feeding amount of the string-like member 30 in each of the plurality of drive sources 20 . Each of the plurality of drive sources 20 may control the position and posture of the distal end link hub 12 with respect to the proximal end link hub 11 based on the winding amount and the feeding amount of the string member 30 detected by the sensor.

The spherical link actuator 100 may have multiple tensioners. Each of the plurality of tensioners is arranged near each of the plurality of string members 30 . By bringing the tensioner into contact with the string-like member 30, the tension applied to the string-like member 30 is always properly maintained.

<Effect of spherical link actuator 100>
In the spherical link actuating device 100, power from a plurality of drive sources 20 is transmitted to the spherical link mechanism 10 via a plurality of string members 30, thereby changing the position and posture of the distal link hub 12 with respect to the proximal link hub 11. is changed. Since the spherical link mechanism 10 and the drive source 20 are connected via the string member 30, the arrangement of the drive source 20 can be easily changed by changing the length of the string member 30. . Thus, according to the spherical link actuation device 100, it is possible to increase the degree of freedom in arranging the drive source 20. FIG.

For example, when the spherical link actuation device 100 is used as an end effector of another device, by arranging the drive source 20 at a position away from the spherical link mechanism 10, the other device can move only the spherical link mechanism 10. Therefore, the weight or moment of inertia of the end effector can be reduced.

When any one of a wire, thread, and chain is used as the string-like member 30, even if the string-like member 30 is twisted due to changes in the position and posture of the distal end link hub 12 with respect to the proximal end link hub 11, the string Power can be transmitted through the shaped member 30 . When a belt is used as the string-like member 30, cutting, slippage, and falling off of the string-like member 30 can be suppressed.

When the string member 30 is connected to the distal link hub 12 or the distal link member 13b, the position and attitude of the distal link hub 12 relative to the proximal link hub 11 can be controlled near the distal link hub 12. A decrease in accuracy in determining the position and attitude of the tip link hub 12 with respect to the base end link hub 11 due to the play (backlash) of the link 13 is suppressed.

When the string-like member 30 is connected to the intermediate link member 13c, the intermediate link member 13c is located on the outermost side of the link 13, so the interference of the string-like member 30 with the link 13 is suppressed. When the string-like member 30 is connected to the base end link member 13a, the string-like member 30 can be shortened. Further, in this case, since the string-like member 30 does not enter the spherical link mechanism 10, interference between the string-like member 30 and the spherical link mechanism 10 can be suppressed.

When the string-like member 30 is wound and unwound by a pulley attached to the shaft 22, wear and friction of the string-like member 30 can be reduced. Also, in this case, the string member 30 is prevented from coming off. Furthermore, in this case, by changing the diameter of the pulley, it is possible to speed up or slow down the winding and unwinding of the string member 30 .

When the spherical link actuator 100 has a plurality of tensioners, the efficiency of power transmission through the string member 30 is improved as the slip loss is reduced. Further, in this case, rattling of the link 13 can be suppressed. If the spherical link actuation device 100 has a plurality of sensors, and the position and attitude of the distal link hub 12 with respect to the proximal link hub 11 are controlled based on the outputs of these sensors, the proximal end of the distal link hub 12 can be detected more accurately. A position and attitude with respect to the link hub 11 can be determined.

(Second embodiment)
A spherical link actuation device (referred to as a “spherical link actuation device 100A”) according to the second embodiment will be described. Here, differences from the spherical link actuation device 100 will be mainly described, and redundant description will not be repeated.

<Structure of Spherical Link Actuator 100A>
FIG. 3 is a perspective view of the spherical link actuator 100A. FIG. 4 is a front view of the spherical link actuator 100A. The spherical link actuator 100</b>A has a spherical link mechanism 10 , multiple drive sources 20 , and multiple cord-like members 30 . In this regard, the configuration of the spherical link actuation device 100A is in common with the configuration of the spherical link actuation device 100. As shown in FIG.

However, the structure of the spherical link actuator 100A differs from the structure of the spherical link actuator 100 with respect to the details of the drive source 20 and the string-like member 30 .

In the spherical link actuation device 100A, the body portions 21 of the plurality of drive sources 20 are arranged in an overlapping manner. Further, in the spherical link actuator 100A, the shafts 22 of the plurality of drive sources 20 are arranged so as to be parallel to the first rotation shafts of the plurality of links 13 .

A timing pulley 23 is attached to the shaft 22 in the spherical link actuator 100A. In the spherical link actuation device 100A, the plurality of cord-like members 30 are, for example, a plurality of annular timing belts. Each of the plurality of annular timing belts is connected to the timing pulley 23 of each of the plurality of drive sources 20 and the base end link member 13a of each of the plurality of links 13 . Therefore, by rotating the timing pulley 23 of each of the plurality of drive sources 20, the base end link member 13a of each of the plurality of links 13 is rotated around the first central axis, and the base end link hub of the tip link hub 12 is rotated. 11 is changed.

<Effect of spherical link actuator 100A>
In the spherical link actuator 100A, a plurality of drive sources 20 are arranged radially around the base end link hub 11 to rotate the base end link member 13a of each of the plurality of links 13 around the first rotation axis. In comparison, since the outward protrusion of the plurality of drive sources 20 can be reduced, the moment of inertia when used as an end effector can be reduced.

FIG. 5 is a perspective view of the spherical link actuator 100A in which the tip link hub 12 is bent at an angle of 90 degrees with respect to the base link hub 11. FIG. As shown in FIG. 5, in the spherical link actuator 100A, since the shafts 22 of the plurality of drive sources 20 are parallel to the first rotation axes of the plurality of links 13, the spherical link actuator The plurality of string-like members 30 (annular timing belt) are not twisted while operating 100A.

In the spherical link actuation device 100A, the string-like member 30 is an annular timing belt, and the timing pulley 23 is attached to the shaft 22. Since the annular timing belt is connected to the timing pulley 23, the string-like member Slip loss can be reduced when 30 transmits power.

(Third Embodiment)
A spherical link actuation device (referred to as a “spherical link actuation device 100B”) according to the third embodiment will be described. Here, differences from the spherical link actuation device 100 will be mainly described, and redundant description will not be repeated.

<Structure of Spherical Link Actuator 100B>
FIG. 6 is a perspective view of the spherical link actuator 100B. FIG. 7 is a front view of the spherical link actuator 100B. The spherical link actuator 100B has a spherical link mechanism 10, a plurality of drive sources 20 (not shown in FIGS. 6 and 7), and a plurality of string members 30. In this regard, the configuration of the spherical link actuation device 100B is in common with the configuration of the spherical link actuation device 100. As shown in FIG.

However, the configuration of the spherical link actuator 100B differs from the configuration of the spherical link actuator 100 with respect to the details of the intermediate link member 13c and the string member 30. As shown in FIG.

In the spherical link actuator 100B, the intermediate link member 13c has a relay portion 13ca. In each of the plurality of links 13, the relay portion 13ca extends in a direction parallel to the first rotation axis and the second rotation axis when the spherical link mechanism 10 is in the origin posture. The spherical link mechanism 10 assumes the origin posture when the first central axis and the second central axis are on the same straight line. The relay portion 13ca is located between one end and the other end of the intermediate link member 13c. That is, the relay portion 13ca overlaps with the intermediate plane of the spherical link mechanism 10 .

The string member 30 has a first portion 31 and a second portion 32 . The first portion 31 and the second portion are, for example, annular string-like members independent of each other. For example, in each of the plurality of links 13, the first portion 31 connects one end of the base end link member 13a and the relay portion 13ca, and the second portion 32 connects one end of the tip link member 13b and the relay portion 13ca. is connected with The second portion 32 is twisted once (figure 8) so that the rotation of the base end link member 13a about the first rotation axis and the rotation of the tip link member 13b about the second rotation axis are reversed. one end of the base end link member 13a and the relay portion 13ca are connected. As a result, each of the plurality of cord-like members 30 is relayed by the relay portion 13ca in each of the plurality of links 13, and then connects one end of the proximal end link member 13a and one end of the distal end link member 13b. are doing.

Therefore, in the spherical link actuating device 100B, each of the plurality of string-like members 30 rotates the base end link member 13a and the tip end link member 13b of each of the plurality of links 13 around the first rotation axis and the second rotation axis, respectively. rotate at the same time. At this time, since the one end of the base end link member 13a and the relay portion 13ca are connected while the second portion 32 is twisted once, the direction of rotation of the base end link member 13a about the first rotation axis is changed. is opposite to the direction of rotation of the tip link member 13b about the second rotation axis, and the amount of rotation of the base end link member 13a about the first rotation axis is the same as the amount of rotation of the tip link member 13b about the second rotation axis. is.

FIG. 8 is a perspective view of the spherical link actuator 100B without omitting all of the string-like members 30. FIG. As shown in FIG. 8, the string member 30 further has a third portion 33. As shown in FIG. The third portion 33 is an annular string-like member and is independent of the first portion 31 and the second portion 32 . The third portion 33 connects one end of the base end link member 13a and the drive source 20 (not shown in FIG. 8). Therefore, in the spherical link actuator 100B, the power of the drive source 20 is transmitted by the third portion 33 to rotate the base end link member 13a in the forward direction, and the forward rotation of the base end link member 13a is caused by the first portion 31. The forward rotation of the relay portion 13ca is reversed by the second portion 32, and the tip link member 13b is rotated in the reverse direction. Each simultaneously rotates the proximal end link member 13a and the distal end link member 13b of each of the plurality of links 13 about the first rotation axis and the second rotation axis, respectively.

<Effect of spherical link actuator 100B>
In the spherical link actuator 100B, the base end link member 13a of each of the plurality of links 13 is rotated around the first rotation axis, or the tip link member 13b of each of the plurality of links 13 is rotated around the second rotation axis. Thereby, the position and posture of the distal end link hub 12 with respect to the proximal end link hub 11 can be changed. From another point of view, in order to change the position and attitude of the distal link hub 12 with respect to the proximal link hub 11, the proximal link member 13a and the distal link member 13b of each of the plurality of links 13 are respectively moved to the second position. It is not necessary to rotate about one axis of rotation and about a second axis of rotation at the same time.

When the spherical link mechanism 10 operates ideally, the base end link hub 11 side of the spherical link mechanism 10 always moves symmetrically with the distal end link hub 12 side of the spherical link mechanism 10 with respect to the intermediate plane. That is, when the spherical link mechanism 10 performs an ideal operation, the direction of rotation of the base end link member 13a around the first rotation axis is opposite to the direction of rotation of the tip link member 13b around the second rotation axis, The amount of rotation of the base end link member 13a around the first rotation axis is the same as the amount of rotation of the tip link member 13b around the second rotation axis. However, the spherical link mechanism 10 is not ideal due to the backlash of the rotational pair of the link 13, the time difference between the power transmission between the proximal end and the distal end, the backlash of each member constituting the spherical link mechanism 10, and the like. It may deviate from normal behavior.

In the spherical link actuating device 100B, the string member 30 causes the proximal end link member 13a and the distal end link member 13b to rotate simultaneously about the first rotation axis and the second rotation axis, respectively. Further, in the spherical link actuator 100B, at this time, the direction of rotation of the base end link member 13a around the first rotation axis is opposite to the direction of rotation of the tip end link member 13b around the second rotation axis. The amount of rotation of the member 13a around the first rotation axis is the same as the amount of rotation of the tip link member 13b around the second rotation axis.

Therefore, according to the spherical link actuating device 100B, the movement of the spherical link mechanism 10 is corrected to a near-ideal operation by reducing the backlash of the rotating pair of the link 13 and reducing the time difference in power transmission between the proximal side and the distal side. Therefore, the accuracy of determination of the position and attitude of the distal end link hub 12 with respect to the proximal end link hub 11 is improved, and vibration is reduced.

(Fourth embodiment)
A spherical link actuation device (referred to as a “spherical link actuation device 100C”) according to the fourth embodiment will be described. Here, differences from the spherical link actuation device 100 will be mainly described, and redundant description will not be repeated.

<Structure of Spherical Link Actuator 100C>
FIG. 9 is a perspective view of the spherical link actuator 100C. FIG. 10 is a perspective view of the pulley 50 included in the spherical link actuator 100C. As shown in FIGS. 9 and 10, the spherical link actuator 100C has a spherical link mechanism 10, multiple drive sources 20, and multiple cord-like members 30. As shown in FIGS. In this regard, the configuration of the spherical link actuation device 100C is common to the configuration of the spherical link actuation device 100. As shown in FIG.

However, the spherical link actuator 100C further includes a plurality of pulleys 50. As shown in FIG. The pulley 50 has a pulley 51 , a pulley shaft member 52 , a support portion 53 and a pulley fixed shaft member 54 . The pulley 51 is attached to the pulley shaft member 52 . The pulley 51 is rotatable around the central axis of the pulley shaft member 52 . The pulley 51 relays the string member 30 between the drive source 20 and the intermediate link member 13c.

The pulley shaft member 52 is attached to the support portion 53 . The pulley 51 may be rotatable about the central axis of the pulley shaft member 52 by rotating with respect to the pulley shaft member 52 , and the pulley shaft member 51 may be rotated with respect to the support portion 53 . 52 may be rotatable around the central axis.

The support portion 53 is attached to the pulley fixed shaft member 54 . The pulley 50 is attached to the base end link hub 11 by a pulley fixing shaft member 54 . Although not shown, the pulley 50 may be attached to a base on which the proximal link hub 11 is placed by a pulley fixing shaft member 54 . The pulley fixed shaft member 54 is preferably rotatable around the central axis of the pulley fixed shaft member 54 . As a result, the pulley 51 is rotatable about the central axis of the pulley fixed shaft member 54 with one rotational degree of freedom. The pulley 51 may be rotatable around the central axis of the pulley fixed shaft member 54 by allowing the support portion 53 to rotate around the central axis of the pulley fixed shaft member 54 . The central axis of the pulley fixed shaft member 54 preferably passes through the first spherical link central point.

In the spherical link actuator 100C, the intermediate link member 13c has a hook portion 13cb. One end of the string-like member 30 (the end opposite to the drive source 20) is hooked on the hook portion 13cb, thereby connecting the string-like member 30 to the intermediate link member 13c. However, the method of connecting the string member 30 to the intermediate link member 13c is not limited to this. The configuration of the spherical link actuator 100C differs from the configuration of the spherical link actuator 100 in these respects.

<Effect of spherical link actuator 100C>
In the spherical link actuator 100</b>C, the string-like member 30 is relayed by the pulley 51 and connected to the intermediate link member 13 c , so the string-like member 30 is less likely to interfere with the spherical link mechanism 10 . Further, when the pulley 51 is rotatable around the central axis of the pulley fixed shaft member 54 , the pulley 51 moves along the central axis of the pulley fixed shaft member 54 following changes in the attitude of the distal end link hub 12 with respect to the base end link hub 11 . Since it rotates around, the string-like member 30 is less likely to drop off from the pulley 51 .

(Fifth embodiment)
A spherical link actuation device (referred to as a “spherical link actuation device 100D”) according to the fifth embodiment will be described. Here, differences from the spherical link actuation device 100C will be mainly described, and redundant description will not be repeated.

<Structure of Spherical Link Actuator 100D>
FIG. 11 is a perspective view of the spherical link actuator 100D. FIG. 12 is a front view of the spherical link actuator 100D. 12, one of the plurality of links 13, one of the plurality of drive sources 20, one of the plurality of string members 30, and one of the plurality of pulleys 50 are shown. One of the pulleys 60 is shown. As shown in FIGS. 11 and 12, the spherical link actuator 100D has a spherical link mechanism 10, a plurality of drive sources 20, a plurality of string members 30, and a plurality of pulleys 50. In this regard, the configuration of the spherical link actuation device 100D is common to the configuration of the spherical link actuation device 100C.

However, the spherical link actuator 100D further includes a plurality of pulleys 60. As shown in FIG. The pulley 60 has a pulley 61 , a pulley shaft member 62 , a support portion 63 and a pulley fixed shaft member 64 . The pulley 61 is attached to the pulley shaft member 62 . The pulley 61 is rotatable around the central axis of the pulley shaft member 62 . In the spherical link actuator 100</b>D, the string member 30 connects the drive source 20 and the tip link hub 12 . The pulleys 51 and 61 relay the string-like member 30 between the drive source 20 and the tip link hub 12 .

The pulley shaft member 62 is attached to the support portion 63 . The pulley 61 may be rotatable about the central axis of the pulley shaft member 62 by rotating with respect to the pulley shaft member 62 , and the pulley shaft member 61 may be rotated with respect to the support portion 63 . 62 may be rotatable around the central axis. The support portion 63 is attached to the pulley fixed shaft member 64 . The pulley 60 is attached to the intermediate link member 13 c by a pulley fixing shaft member 64 . More specifically, pulley 60 is attached to intermediate link member 13c such that pulley 61 is outside intermediate link member 13c. The pulley fixed shaft member 64 cannot rotate with respect to the intermediate link member 13c. Therefore, the pulley 61 cannot rotate with respect to the intermediate link member 13c.

In the spherical link actuator 100D, the tip link hub 12 has a hook portion 12a. The string-like member 30 is connected to the tip link hub 12 by hooking one end of the string-like member 30 (the end opposite to the drive source 20) on the hook portion 12a. However, the method of connecting the string member 30 to the tip link hub 12 is not limited to this. In these respects, the configuration of the spherical link actuator 100D differs from the configuration of the spherical link actuator 100C.

<Modification>
FIG. 13 is a perspective view of a spherical link actuator 100D according to a modification. 13, one of the plurality of links 13, one of the plurality of drive sources 20, one of the plurality of string members 30, and one of the plurality of pulleys 50 are shown. One of the pulleys 60 is shown. As shown in FIG. 13, the pulley 61 (pulley 60) may be inside the intermediate link member 13c. Although not shown, the pulley 50 may be omitted in the spherical link actuator 100D. In this case, the string-like member 30 is relayed only by the pulley 61 between the tip link hub 12 and the drive source 20 .

<Effect of spherical link actuator 100D>
In the spherical link actuation device 100D, since the string-like member 30 is connected to the distal end link hub 12 and the drive source 20, the string-like member 30 directly controls the posture of the distal end link hub 12 with respect to the proximal end link hub 11. will be Therefore, according to the spherical link actuating device 100D, the accuracy of attitude control of the distal end link hub 12 with respect to the proximal end link hub 11 is enhanced. Further, in the spherical link actuator 100</b>D, since the string-like member 30 is relayed by the pulleys 51 and 61 , the string-like member 30 is less likely to interfere with the spherical link mechanism 10 .

If the pulley 60 (pulley 61) is outside the intermediate link member 13c, the string member 30 is less likely to interfere with the spherical link mechanism 10. FIG. When the pulley 60 (pulley 61) is inside the intermediate link member 13c, it is possible to downsize the spherical link actuator 100D.

(Sixth embodiment)
A spherical link actuation device (referred to as a “spherical link actuation device 100E”) according to the sixth embodiment will be described. Here, differences from the spherical link actuation device 100C will be mainly described, and redundant description will not be repeated.

<Structure of Spherical Link Actuator 100E>
FIG. 14 is a perspective view of the spherical link actuator 100E. FIG. 15 is a perspective view of the drive converting portion 70 included in the spherical link actuator 100E. 15, the tip link hub 12 and one tip link member 13b of the plurality of links 13 are shown together with the drive converter 70. As shown in FIG. As shown in FIGS. 14 and 15, the spherical link actuator 100E includes a spherical link mechanism 10, a plurality of drive sources 20 (not shown in FIG. 14), a plurality of cord-like members 30, and a plurality of A pulley 50 is provided. In this regard, the configuration of the spherical link actuation device 100E is common to the configuration of the spherical link actuation device 100C.

However, the spherical link actuation device 100E further has a plurality of drive conversion parts 70. As shown in FIG. The drive conversion section 70 has a pulley 71 , a pulley shaft member 72 , a support section 73 , a gear 74 , a gear 75 , and a gear fixing shaft member 76 . In addition, in the spherical link actuator 100E, the pulley 50 is attached to the base end link hub 11 so that the central axis of the pulley fixed shaft member 54 coincides with the first rotation axis.

The pulley 71 is attached to the pulley shaft member 72 . The pulley 71 is rotatable around the central axis of the pulley shaft member 72 . The central axis of the pulley shaft member 72 is orthogonal to the central axis of the gear fixing shaft member 76 . In the spherical link actuator 100</b>E, the string member 30 connects the drive source 20 and the pulley 71 . Therefore, the pulley 71 is rotated around the central axis of the pulley shaft member 72 by the drive source 20 and the string member 30 . Since the string-like member 30 is relayed by the pulley 51 between the drive source 20 and the pulley 71, the pulley 51 is rotated around the central axis of the pulley shaft member 52 by the drive source 20 and the string-like member 30. .

The pulley shaft member 72 is attached to the support portion 73 . The pulley 71 may be rotatable about the central axis of the pulley shaft member 72 by rotating with respect to the pulley shaft member 72 , and the pulley shaft member 71 may be rotated with respect to the support portion 73 . It may be rotatable around the central axis of 72 .

A gear 74 is fixed to the pulley 71 . Therefore, the gear 74 can rotate around the central axis of the pulley shaft member 72 together with the pulley 71 . The gear 75 is fixed to a gear fixing shaft member 76 . By transmitting the rotational force of the gear 74 to the gear 75 , the gear 75 is rotated around the central axis of the gear fixing shaft member 76 . A central axis of the gear fixing shaft member 76 extends along the second rotation axis. The gear fixing shaft member 76 is connected to the tip link hub 12 so as to be rotatable around the second rotation axis. The gear fixing shaft member 76 is fixed to one end of the tip link member 13b. Therefore, the torque of the gear 74 is transmitted to the gear 75 so that the gear 75 rotates around the second rotation axis together with the tip link member 13b and the gear fixing shaft member 76 .

Gears 74 and 75 are, for example, bevel gears. However, the gears 74 and 75 are not limited to this, and are not particularly limited as long as the rotational force of the gear 74 can be transmitted to the gear 75 after rotating the rotation direction by 90°. For example, as the gears 74 and 75, magnetic gears, helical gears, etc. can be used in addition to bevel gears. The number of teeth of the gear 74 and the number of teeth of the gear 75 may be equal or different.

The support portion 73 is attached to the gear fixing shaft member 76 . The support portion 73 is rotatable around the central axis of the gear fixing shaft member 76, that is, around the second rotation axis, independently of the gear fixing shaft member 76. As shown in FIG. Therefore, the pulley 71 attached to the support portion 53 via the pulley shaft member 72 and the gear 74 fixed to the pulley 71 are also rotatable around the second rotation axis independently of the gear fixing shaft member 76. be. Pulleys 51 and 71 are preferably parallel regardless of the orientation of distal link hub 12 with respect to proximal link hub 11 . More preferably, pulley 51 and pulley 71 are on the same plane regardless of the orientation of distal link hub 12 with respect to proximal link hub 11 .

The distance between the pulleys 51 and 71 changes according to the attitude of the distal end link hub 12 with respect to the proximal end link hub 11 . The spherical link actuator 100E has a plurality of tension adjustment functions (not shown) that can adjust the tension of the string-like member 30 between the pulleys 51 and 71 according to the distance between the pulleys 51 and 71. It is preferable to further have Each of the plurality of tension adjustment mechanisms is attached to each of the plurality of string members 30 . A tension adjustment mechanism is, for example, a tensioner. In these respects, the configuration of the spherical link actuator 100E differs from the configuration of the spherical link actuator 100C.

<Effect of spherical link actuator 100E>
In the spherical link actuator 100E, the pulley 71 and the gear 74 are rotated by the drive source 20 and the string member 30, and the rotational force of the gear 74 is transmitted to the gear 75, thereby rotating the tip link member 13b around the second rotation axis. By rotating, the attitude of the distal end link hub 12 with respect to the proximal end link hub 11 is changed. Thus, in the spherical link actuator 100E, the attitude control of the distal end link hub 12 with respect to the proximal end link hub 11 is performed at a position close to the distal end link hub 12, and the attitude control of the distal end link hub 12 with respect to the proximal end link hub 11 is performed. Increased accuracy.

In the spherical link actuator 100E, the pulley 51 is rotatable around the central axis (first rotational axis) of the pulley fixed shaft member 54, and the pulley 71 is rotatable around the central axis (second rotational axis) of the gear fixed shaft member 76. ), the pulleys 51 and 71 are parallel (or the pulleys 51 and 71 are on the same plane) regardless of the attitude of the distal link hub 12 with respect to the proximal link hub 11. above) can be maintained. As a result, according to the spherical link actuator 100</b>E, twisting of the string-like member 30 between the pulleys 51 and 71 and falling off of the string-like member 30 from the pulleys 51 and 71 can be suppressed.

Although the embodiment of the present invention has been described as above, it is also possible to modify the above-described embodiment in various ways. Also, the scope of the present invention is not limited to the embodiments described above. The scope of the present invention is indicated by the scope of claims, and is intended to include all changes within the meaning and scope of equivalence to the scope of claims.

100 spherical link actuator 10 spherical link mechanism 11 proximal link hub 12 distal link hub 12a hook portion 13 link 13a proximal link member 13b distal link member 13c intermediate link member 13ca relay portion 13cb Hook part 20 Drive source 21 Body part 22 Shaft 23 Timing pulley 30 String member 31 First part 32 Second part 33 Third part 40 Case 50,60 Pulley 51,61 DESCRIPTION OF SYMBOLS Pulleys 52, 62 pulley shaft member 53, 63 support portion 54, 64 pulley fixed shaft member 70 drive conversion portion 71 pulley 72 pulley shaft member 73 support portion 74, 75 gears 76 gear fixed shaft member , 100A, 100B, 100C, 100D, 100E spherical link actuators.

Claims (22)

a spherical link mechanism;
a plurality of string-like members;
with a plurality of drive sources,
The spherical link mechanism has a proximal link hub, a distal link hub, and a plurality of links connecting the proximal link hub and the distal link hub,
each of the plurality of links includes a proximal link member, a distal link member, and an intermediate link member;
The proximal link member is connected to the proximal link hub at one end thereof so as to be rotatable about a first rotation axis,
The tip link member is connected to the tip link hub at one end of the tip link member so as to be rotatable about a second rotation axis,
The intermediate link member is connected at one end of the intermediate link member to the other end of the base end link member so as to be rotatable about a third rotation axis, and at the other end of the intermediate link member, the tip link member. is rotatably connected to the other end of the fourth rotation axis,
the center axis of the proximal link hub, the first rotation axis, and the third rotation axis intersect at a first spherical link center point;
the center axis of the tip link hub, the second rotation axis and the fourth rotation axis intersect at a second spherical link center point;
The proximal end link hub and the distal end link hub respectively move on a first moving spherical surface centered on the first spherical link center point and on a second moving spherical surface centered on the second spherical link center point. ,
each of the plurality of string-like members is connected to each of the plurality of drive sources and the spherical link mechanism;
The power of each of the plurality of drive sources is transmitted to the spherical link mechanism via each of the plurality of string-like members, thereby changing the position and posture of the tip link hub with respect to the base end link hub. , spherical link actuator. The plurality of drive sources according to claim 1, wherein each of said plurality of drive sources changes the position and attitude of said tip link hub relative to said base end link hub by adjusting the tension applied to each of said plurality of string members. Spherical link actuator. 3. The spherical link actuator according to claim 2, wherein each of said plurality of string members connects said intermediate link member of each of said plurality of links and each of said plurality of drive sources. further comprising a plurality of pulleys attached to the proximal link hub;
each of the plurality of pulleys has a pulley and a pulley fixed shaft member, and is attached to the base end link hub by the pulley fixed shaft member;
4. The spherical link actuator according to claim 3, wherein each of said plurality of string-like members is relayed by said pulley of each of said plurality of pulleys. 5. The spherical link actuator according to claim 4, wherein the pulley in each of the plurality of pulleys is rotatable about the central axis of the pulley fixed shaft member with one rotational degree of freedom. 6. The spherical link actuator according to claim 5, wherein in each of said plurality of pulleys, the center axis of said pulley fixed shaft member passes through said first spherical link center point. Further comprising a plurality of first pulleys and a plurality of second pulleys,
each of the plurality of string-like members connects the tip link hub and each of the plurality of drive sources;
each of the plurality of first pulleys has a first pulley and a first pulley fixed shaft member, and is attached to the base end link hub by the first pulley fixed shaft member;
Each of the plurality of second pulleys has a second pulley and a second pulley fixed shaft member, and is attached to the intermediate link member of each of the plurality of links by the second pulley fixed shaft member. ,
3. The spherical surface according to claim 2, wherein each of said plurality of string-like members is relayed by said first pulley of each of said plurality of first pulleys and said second pulley of each of said plurality of second pulleys. link actuator. In each of the plurality of first pulleys, the first pulley is rotatable with one rotational degree of freedom around the central axis of the first pulley fixed shaft member,
8. The spherical link actuator of claim 7, wherein each of said plurality of second pulleys is non-rotatable relative to said intermediate link member of each of said plurality of links. 8. The spherical link actuator of claim 7, wherein said second pulley of each of said plurality of second pulleys is located outside said intermediate link member of each of said plurality of links. 8. The spherical link actuator of claim 7, wherein said second pulley of each of said plurality of second pulleys is located inside said intermediate link member of each of said plurality of links. 3. The spherical link actuation according to claim 2, wherein each of said plurality of string members connects said tip link hub or said tip link member of each of said plurality of links and each of said plurality of drive sources. Device. each of the plurality of drive sources has a pulley,
Each of the plurality of drive sources adjusts the tension applied to each of the plurality of string-like members by rotating the pulley to wind up or let out each of the plurality of string-like members. A spherical link actuator as described. further equipped with multiple sensors,
13. The spherical surface according to claim 12, wherein each of said plurality of sensors is configured to be capable of detecting an amount of winding or feeding out of each of said plurality of string members by said pulley of each of said plurality of drive sources. link actuator. The spherical link actuator according to any one of claims 2 to 13, wherein the plurality of string-like members are a plurality of wires, a plurality of threads, a plurality of chains or a plurality of belts. Equipped with multiple tensioners,
The spherical link actuator according to any one of claims 2 to 13, wherein each of said plurality of tensioners is configured to be able to adjust the tension applied to each of said plurality of string members. Each of the plurality of drive sources rotates the base end link member of each of the plurality of links around the first rotation axis via each of the plurality of string members, thereby driving the tip link hub. 2. The spherical link actuator of claim 1, wherein the position and attitude are variable. The plurality of cord-like members are a plurality of annular timing belts,
each of the plurality of drive sources has a timing pulley,
17. The spherical link actuation of claim 16, wherein said proximal link member of each of said plurality of links and said timing pulley of each of said plurality of drive sources are coupled by each of said plurality of annular timing belts. Device. a plurality of pulleys;
further comprising a plurality of drive conversion units,
each of the plurality of pulleys has a first pulley and a pulley fixed shaft member, and is attached to the base end link hub by the pulley fixed shaft member;
In each of the plurality of pulleys, the first pulley is rotatable about a central axis of the pulley fixed shaft member with one rotational degree of freedom,
Each of the plurality of drive conversion portions includes a support portion, a second pulley attached to the support portion, a first gear rotating together with the second pulley, and a rotational force of the first gear being transmitted. Having a second gear and a gear fixing shaft member fixed to the second gear,
Each of the plurality of string-like members is relayed to the first pulley of each of the plurality of pulleys to connect the second pulley of each of the plurality of drive sources and each of the plurality of drive sources. cage,
The gear fixing shaft member of each of the plurality of drive converting portions is fixed to one end of the tip link member of each of the plurality of links, and is rotatable around the second rotation axis. connected to the hub,
2. The spherical link actuator according to claim 1, wherein in each of said plurality of drive conversion parts, said support part is rotatable around said second rotation axis independently of said gear fixing shaft member. 19. The spherical link actuator according to claim 18, wherein said first pulley of each of said plurality of pulleys is coplanar with said second pulley of each of said plurality of drive converting portions. It is further equipped with multiple tension adjustment mechanisms,
Each of the plurality of tension adjusting mechanisms applies tension to each of the plurality of cord-like members between the first pulley of each of the plurality of pulleys and the second pulley of each of the plurality of drive sources. 20. A spherical link actuator according to claim 18 or claim 19, wherein is configured to be adjustable. Each of the plurality of drive sources rotates the base end link member and the tip end link member of each of the plurality of links around the first rotation axis and the second rotation via each of the plurality of string members, respectively. Simultaneously rotate around the axis,
In each of the plurality of links, the direction of rotation of the base end link member about the first rotation axis is opposite to the direction of rotation of the tip link member about the second rotation axis, and the direction of rotation of the base end link member about the second rotation axis 2. A spherical link actuator according to claim 1, wherein the amount of rotation about said first axis of rotation is the same as the amount of rotation of said tip link member about said second axis of rotation. 22. The spherical surface according to claim 21, wherein each of said string-like members is connected to said proximal end link member and said distal end link member after being relayed by said intermediate link member in each of said plurality of links. link actuator.

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