JP2024034842A - link actuator - Google Patents

Abstract

An object of the present invention is to provide a link actuating device that can increase the rigidity of a parallel link mechanism and increase the versatility of work. A link actuating device (7) includes a parallel link mechanism (9) and an attitude control actuator (10). The link hub 13 on the distal end side and the link hub 12 on the proximal end side are movably connected to each other by a rod-shaped member Rd, and a connecting portion connects the rod-shaped member Rd to the link hubs 12 and 13 on the proximal side and the distal side, respectively. is provided. A conversion mechanism 1 that converts the rotational movement of the rod-like member Rd into a translational movement of the translational portions 23, 23 along the rod-like member Rd, and a conversion mechanism 1 provided in each translational portion 23 and provided on the link hubs 12, 13 on the proximal side and the distal side. Pads 2A, 2A correct the parallel link mechanism 9 to a predetermined posture by contacting each other, and a rotational drive source Rs provided on the link hub 12 on the proximal end side and rotationally drives the rod-shaped member Rd together with each connecting portion. Equipped with [Selection diagram] Figure 2A

Description

TECHNICAL FIELD The present invention relates to a link actuating device used in equipment that requires a precise and wide operating range, such as medical equipment or industrial equipment.

Patent Document 1 discloses a work device that has a base plate and a traveling plate, connects them with a plurality of links, and performs a predetermined work using a parallel link mechanism that moves the traveling plate by cooperatively operating these links. is proposed.
Patent Document 2 proposes a link actuating device that is compact, yet capable of high speed, high precision, and operation over a wide range of motion.
Patent Document 3 proposes a parallel link mechanism in which upper and lower spherical links are connected by a ball joint, which is a spherical member, in order to strengthen rigidity.

Japanese Patent Application Publication No. 2000-94245 US Patent No. 5,893,296 Japanese Patent Application Publication No. 2005-351379

When a conventional parallel link mechanism is required to perform work that involves contact with parts or pedestals, such as during assembly, it cannot be used because of its low rigidity.

An object of the present invention is to provide a link actuating device that can increase the rigidity of a parallel link mechanism and increase the versatility of work.

In the link actuating device of the present invention, a link hub on a distal side is connected to a link hub on a proximal side so as to be changeable in posture via two or more sets of link mechanisms, and each of the link mechanisms is connected to a link hub on the proximal side, respectively. proximal and distal end link members, one end of which is rotatably connected to the link hub and the distal link hub; a parallel link mechanism using a spherical link mechanism having central link members rotatably connected to each other;
A link actuating device comprising: a posture control actuator that is provided in the two or more sets of link mechanisms in this parallel link mechanism and arbitrarily controls the posture of the link hub on the distal end side,
The link hub on the distal side and the link hub on the proximal side are movably connected to each other by a rod-shaped member, and the rod-shaped member connects at least the spherical link center of the spherical link mechanism on the proximal side and the spherical link mechanism on the distal side. A member that passes through the center of the spherical link, and is provided with a connecting portion that connects the rod-shaped member and the link hubs on the proximal end and distal sides, respectively, and is connected to the link hubs on the proximal end and distal sides. , the rod-shaped member and each connecting portion are rotatably connected around their respective axes,
a conversion mechanism that converts rotational movement of the rod-shaped member into translational movement of a translational portion along the rod-shaped member;
a posture correction member that is provided in the translation portion and corrects the parallel link mechanism to a predetermined posture by contacting the link hubs on the proximal end side and the distal side, respectively;
A rotational drive source is provided on the link hub on the proximal end side and rotates the rod-shaped member together with each of the connecting portions.
The determined posture is a posture arbitrarily determined by design or the like, and is determined by finding an appropriate posture by, for example, testing and/or simulation.

According to this configuration, the rod-shaped member and each connecting portion are rotatably connected to the link hubs on the proximal end side and the distal side, and a conversion mechanism is provided that converts the rotational movement of the rod-like member into the translational movement of the translational portion. ing. When correcting the parallel link mechanism to a predetermined posture, the rotational drive source rotates the rod-shaped member together with each connecting portion in a predetermined rotational direction, so that the translation portion translates along the rod-shaped member. As a result, the posture correction member provided at the translation portion is translated in a direction approaching the corresponding link hub. Finally, the posture correction member comes into contact with the link hubs on the proximal side and the distal side, respectively, thereby correcting the parallel link mechanism into a predetermined posture. This improves the inclination rigidity of the link hubs on the proximal side and the distal side, thereby improving the inclination rigidity of the entire parallel link mechanism. By increasing the rigidity of the parallel link mechanism in this way, it is possible to flexibly respond to high-load work, etc., and the versatility of the work can be increased.

The conversion mechanism is a feed screw mechanism having a threaded portion provided on the outer periphery of the rod-shaped member, and the translation portion which is a nut portion that is screwed onto the threaded portion and moves in translation by rotation of the rod-shaped member. Good too. In this case, since the translation portion can be provided near the middle in the longitudinal direction of the rod-shaped member, the posture correction member can be moved close to or away from the corresponding link hub regardless of the configuration of the link actuating device. For example, even when an end effector is attached to the link hub on the distal end side, the posture correction member can be freely translated without interfering with the end effector.

The posture correction member may be two pads each having a plane perpendicular to the central axis of the rod-shaped member, and the planes of these pads may contact the link hubs on the proximal end side and the distal side. In this case, by bringing the plane of each pad into contact with the corresponding link hub, the posture of the parallel link mechanism can be reliably corrected and restrained. Furthermore, by limiting the portion of the posture correction member that interferes with the link hub to a flat surface, it is possible to instantly switch between interference and non-interference.

The rod-shaped member and each connecting portion may have a hollow structure that communicates with each other. In this case, the cable of the end effector, etc. can be passed through the rod-shaped member and each connecting portion.

In the link actuating device of the present invention, the translation portion is translated by rotationally driving the rod-shaped member together with each connecting portion in a predetermined rotational direction by a rotational drive source. As a result, the posture correction member provided on the translation portion comes into contact with the link hubs on the proximal side and the distal side, respectively, thereby correcting the parallel link mechanism to a predetermined posture. This improves the inclination rigidity of the link hubs on the proximal end side and the distal end side, thereby improving the inclination rigidity of the entire parallel link mechanism and increasing the versatility of the work.

FIG. 1 is a perspective view of a link actuating device according to a first embodiment of the present invention. It is a front view of the same link actuation device. It is a side view of the same link actuation device. FIG. 3 is a longitudinal cross-sectional view of the link actuating device in a state where the posture is not corrected. It is a top view of the same link actuation device. It is a figure which expresses one link mechanism of the parallel link mechanism of the same link actuation device by a straight line. It is a perspective view of the conversion mechanism of the same parallel link mechanism. It is a perspective view of the same conversion mechanism seen from another direction. FIG. 3 is a perspective view of the link actuating device in a state in which the posture is being corrected. FIG. 3 is a front view of the link actuating device in a state in which the posture is being corrected. FIG. 3 is a side view of the link actuating device in a state where its posture is being corrected. FIG. 3 is a longitudinal cross-sectional view of the link actuating device in a state where its posture is being corrected. FIG. 3 is a plan view of the link actuating device in a state in which the posture is being corrected. It is a perspective view of the state in which the posture of the link actuating device is corrected. FIG. 3 is a front view of the link actuating device in a state in which its posture has been corrected. FIG. 3 is a side view of the link actuating device in a state where its posture has been corrected. FIG. 3 is a longitudinal cross-sectional view of the link actuating device in a state in which its posture has been corrected. It is a perspective view of the conversion mechanism at the time of posture correction of the same link actuation device.

[First embodiment]
A link actuating device according to an embodiment of the present invention will be described with reference to FIGS. 1 to 14.
<Schematic structure of link actuating device>
As shown in FIG. 1, the link actuating device 7 includes a parallel link mechanism 9, an attitude control actuator 10 that arbitrarily controls the attitude of the parallel link mechanism 9, and a control device Cu. The link actuating device 7 is used, for example, in medical equipment or industrial equipment. The link actuating device 7 performs work by positioning an end effector (not shown) attached to a link hub 13 on the distal end side, which will be described later, with respect to a workpiece (not shown). The control device Cu is electrically connected to an attitude control actuator 10 and a rotational drive source Rs, which will be described later, and these attitude control actuator 10 and rotational drive source Rs are synchronously controlled by the control device Cu.

<Parallel link mechanism>
As shown in FIG. 2A, the parallel link mechanism 9 includes a disk-shaped pad 2A, which is a posture correction member, and a rotational drive source Rs. In the parallel link mechanism 9, a link hub 12 on the proximal side and a link hub 13 on the distal side are connected via three sets of link mechanisms 14 so that the posture can be changed. The number of link mechanisms 14 may be two or four or more. The parallel link mechanism 9 is configured to be able to be traded independently in the market.

Each link mechanism 14 has an end link member 15 on the proximal side, an end link member 16 on the distal side, and a central link member 17, and forms a four-bar chain link mechanism consisting of four rotating pairs. As shown in FIG. 1, one end of the proximal end link member 15 is rotatably connected to the proximal link hub 12 around a first rotation axis 22a. has been done. One end of the distal end link member 16 is connected to the distal link hub 13 so as to be rotatable about the second rotating shaft 22b.

As shown in FIG. 2B, the central link member 17 is connected at one end of the central link member 17 to the other end of the proximal end link member 15 so as to be rotatable about the third rotation axis 22c. At the same time, the other end of the central link member 17 is connected to the other end of the end link member 16 on the distal end side so as to be rotatable around the fourth rotation axis 22d.

The first rotating shaft 22a shown in FIG. 1 is a rotating shaft around the central axis of each rotating pair T1 (FIG. 5) of the link hub 12 on the proximal end and the end link member 15 on the proximal end. The second rotating shaft 22b is a rotating shaft around the central axis of the rotating pair T2 (FIG. 5) of the link hub 13 on the distal end side and the end link member 16 on the distal end side. The third rotating shaft 22c shown in FIG. 2B is a rotating shaft around the central axis of each rotating pair T3 (FIG. 5) of the proximal end link member 15 and the central link member 17. The fourth rotation axis 22d is a rotation axis around the central axis of each rotation pair T4 (FIG. 5) of the end link member 16 on the distal end side and the center link member 17.

As shown in FIG. 2A, the parallel link mechanism 9 has a structure in which two spherical link mechanisms 9a and 9b are combined. In the first spherical link mechanism 9a on the proximal end, the central axis QA of the link hub 12 on the proximal end and each central axis of the first rotating shaft 22a and the third rotating shaft 22c (FIG. 2B) are aligned with the base. They intersect at the end-side spherical link center PA (FIG. 5). In the second spherical link mechanism 9b on the distal side, the central axis QB of the link hub 13 on the distal side and the respective central axes of the second rotating shaft 22b and the fourth rotating shaft 22d (FIG. 2B) are connected to each other on the distal side. They intersect at the spherical link center PB (FIG. 5).

In addition, in this embodiment, as shown in FIG. 4, between the center of each rotating pair part T1 of the proximal link hub 12 and the proximal end link member 15 and the proximal spherical link center PA. The distance is the same. The distance between the center of each rotating pair T3 of the end link member 15 and the central link member 17 on the proximal end and the spherical link center PA on the proximal end is the same. Similarly, the distance between the center of each rotating pair T2 of the link hub 13 on the distal side and the end link member 16 on the distal side and the spherical link center PB on the distal side is the same. The distances between the centers of the rotating pair parts T4 of the end link member 16 and the central link member 17 on the distal end side and the spherical link center PB on the distal end side are the same, but the distances may be different. The third and fourth rotating shafts 22c and 22d shown in FIG. 2B of each rotating pair T3 and T4 have a certain intersecting angle (also referred to as an "axis angle"), but they may be parallel. The arm angle, which is the angle formed by the first rotating shaft 22a and the third rotating shaft 22c, is defined as a predetermined angle.

The three sets of link mechanisms 14 shown in FIG. 2A have the same geometric shape. As shown in FIG. 5, geometrically the same shape means a geometric model in which each link member 15, 16, 17 is expressed as a straight line, that is, each rotating pair T1, T3, T4, T2, and these rotating pairs No matter what posture the model expressed by the straight line connecting parts T1, T3, T4, and T2 takes, the proximal end part and the distal end part are symmetrical with respect to the central part of the central link member 17. say that it is. In addition, each rotating pair part T1, T3, T4, T2 may be called "each rotating pair part T1 etc." in the following description. FIG. 5 is a diagram depicting one set of link mechanisms 14 using straight lines. The parallel link mechanism 9 of this embodiment is of a rotationally symmetrical type, with a link hub 12 on the proximal side and an end link member 15 on the proximal side, and a link hub 13 on the distal side and an end link member 16 on the distal side. The positional relationship is rotationally symmetrical with respect to the center line C of the central link member 17.

The link hub 12 on the proximal side, the link hub 13 on the distal side, and the three sets of link mechanisms 14 change the posture of the link hub 13 on the distal side with respect to the link hub 12 on the proximal side with two rotational degrees of freedom. It is a flexible mechanism. Although this two-degree-of-freedom mechanism is compact, it is possible to have a wide movable range of the link hub 13 on the distal side relative to the link hub 12 on the proximal side.

The vertical angle at which the central axis QB of the link hub 13 on the distal end is inclined with respect to the central axis QA of the link hub 12 on the proximal end is referred to as a bending angle θ. The maximum value of this bending angle θ is referred to as the maximum bending angle θ _max . Further, the turning angle φ of the link hub 13 on the distal side with respect to the link hub 12 on the proximal side can be set in the range of 0° to 360°. The turning angle φ is the horizontal angle at which the central axis QB of the link hub 13 on the distal end is inclined with respect to the central axis QA of the link hub 12 on the proximal end.

The posture change of the distal link hub 13 with respect to the proximal link hub 12 is performed using the intersection O between the central axis QA of the proximal link hub 12 and the central axis QB of the distal link hub 13 as the center of rotation. be exposed. 2A shows a state in which the central axis QA of the proximal link hub 12 and the central axis QB of the distal link hub 13 are on the same line, and FIG. 5 shows that the central axis QB is on the same line with respect to the central axis QA. This shows the state where the operating angle (bending angle) is taken. Even if the attitude of the distal link hub 13 with respect to the proximal link hub 12 changes, the distance L between the proximal and distal spherical link centers PA and PB does not change.

The three sets of link mechanisms 14 shown in FIG. 4 are arranged at equal intervals on the circumference with 120 degree intervals in the circumferential direction, but they do not necessarily need to be arranged at equal intervals on the circumference. The link hub 12 on the proximal side shown in FIG. 1 includes, for example, a hexagonal proximal support member 12a in plan view, and a proximal member main body 12b fixed to the upper part of the proximal support member 12a. The base end member main body 12b has a hexagonal tube shape arranged concentrically with the base end support member 12a, and has a circular hole formed in the center thereof to rotatably support a connecting portion 3, which will be described later. The center of the hole in the plan view of the proximal member main body 12b coincides with the spherical link center PA (FIG. 5) on the proximal end side. Three flanges 12aa protruding in one direction in the axial direction are disposed integrally with the proximal support member 12a at equal circumferential intervals on the outer peripheral portion of the proximal support member 12a.

Each rotating pair T1 (FIG. 5) and the like is provided with a bearing (not shown) as means for reducing rotational resistance of the rotating pair. In the rotating pair T1 (FIG. 5) of the link hub 12 on the proximal side and the end link member 15 on the proximal side, the first rotating shaft 22a is rotatably attached to each flange 12aa via the bearing or the like. connected. One end of the proximal end link member 15 is connected to the first rotating shaft 22a, and the first rotating shaft 22a and the proximal end link member 15 rotate together.

As shown in FIG. 4, the link hub 13 on the distal end side has a hexagonal cylinder shape similar to the base end member main body 12b (FIG. 1), and has a circular hole in the center that rotatably supports a connecting portion 4, which will be described later. 13a is formed. The center of the hole 13a in the plan view of the link hub 13 on the distal end side coincides with the spherical link center PB on the distal end side. On the outer peripheral surface of the link hub 13 on the distal end side, three second rotating shafts 22b projecting radially outward are supported at equal circumferential intervals. The axis of each second rotating shaft 22b intersects with the central axis QB of the link hub 13 on the distal end side. One end of the end link member 16 on the distal side is connected to the second rotating shaft 22b. As shown in FIG. 2B, a fourth rotation shaft 22d rotatably connected to the other end of the central link member 17 is connected to the other end of the end link member 16 on the distal side.

<Rod-shaped member and connecting part>
FIG. 3 is a sectional view taken along the line III--III in FIG. 4. As shown in FIG. 3, the link hub 13 on the distal end side and the link hub 12 on the proximal end side are movably connected to each other by a rod-shaped member Rd. The rod-shaped member Rd has at least a spherical link center PA (FIG. 5) in the first spherical link mechanism 9a (FIG. 2A) on the proximal end side and a spherical link center PA (FIG. 5) in the second spherical link mechanism 9b (FIG. 2A) on the distal end side. This is a member that passes through the PB (Fig. 5). Proximal and distal connecting portions 3 and 4 are provided to connect the rod-like member Rd and the proximal and distal link hubs 12 and 13, respectively. The rod-shaped member Rd and the connecting portions 3, 4 are rotatably connected to the link hubs 12, 13 on the proximal end side and the distal end side about their respective axes. In other words, the rod-like member Rd and the proximal and distal connecting portions 3 and 4 are rotatable independently with respect to the link hubs 12 and 13. In the following description, the rod-shaped member Rd and the connecting portions 3 and 4 on the base end side and the distal end side may be referred to as "rod-shaped member etc.".

The rod-shaped member Rd includes a shaft member 5a and a cylindrical member 5b that is fitted and fixed to a longitudinally intermediate portion of the shaft member 5a. One longitudinal end of the shaft member 5a is connected to a link hub 12 on the proximal end, and the other longitudinal end of the shaft member 5a is connected to a link hub 13 on the distal end.

As shown in FIG. 1, constant velocity joints such as Zeppa type constant velocity joints each having a ball are used as the connecting portions 3 and 4 on the base end side and the distal end side. Each connecting portion 3, 4 to which a constant velocity joint is applied has inner and outer rings IR and OR shown in FIG. 4) and a holder (not shown) that holds the holder. The outer ring OR of the connecting portion 3 on the proximal end side is rotatably supported in the hole of the proximal member body 12b (FIG. 1) via a slide bearing (not shown) or the like. The inner ring IR of the connecting portion 3 on the proximal end has a bending angle of 1/2θ and a turning angle of φ with respect to the link hub 12 on the proximal end, respectively, starting from the spherical link center PA on the proximal end shown in FIG. It is angularly displaceable and rotates in three degrees of freedom around the central axis of the rod-shaped member Rd shown in FIG.

As shown in FIG. 4, the outer ring OR of the coupling portion 4 on the distal end side is rotatably supported in the hole 13a of the link hub 13 on the distal end side via a sliding bearing or the like (not shown). The inner ring IR of the connecting portion 4 on the distal end side rotates in three degrees of freedom with respect to the link hub 13 on the distal end side, starting from the spherical link center PB on the distal end side, similarly to the proximal end side. Note that the connecting portions 3 and 4 in FIG. 3 are not limited to constant velocity joints, and for example, a connecting structure such as a universal joint such as a Cardan joint may be applied.

<About conversion mechanism, posture correction member, etc.>
As shown in FIG. 6A, the conversion mechanism 1 converts the rotational movement of the rod-like member Rd into the translational movement of two annular translational portions 23, 23 along the longitudinal direction of the rod-like member Rd. It is a mechanism. The conversion mechanism 1 is arranged near the longitudinal center of the rod-shaped member Rd. The translation parts 23, 23 are posture correction members that correct the parallel link mechanism 9 (FIG. 2A) to a predetermined posture by contacting the link hubs 12, 13 (FIG. 3) on the proximal side and the distal side, respectively. Certain disc-shaped pads 2A, 2A are provided. As shown in FIG. 6B, the conversion mechanism 1 includes a feed screw mechanism Fs having threaded portions 25a, 25b and translational portions 23, 23 which are nut portions, and a rotation stopper member 26 for stopping rotation of each translational portion 23. and has.

The threaded portions 25a and 25b are provided on the outer periphery of the cylindrical member 5b in the rod-like member Rd shown in FIG. Although trapezoidal threads are applied to the threaded portions 25a and 25b in FIG. 6A in this example, it is also possible to apply sliding screws or ball screws. The threaded portions 25a, 25b are set such that the winding directions of the screws are set in opposite directions on the distal end and the proximal end with the longitudinal intermediate portion as a boundary, and the threaded portions 25a, 25b on the proximal end and distal end sides are set at the same pitch. It is set. The translation parts 23, 23 are screwed into the threaded parts 25a, 25b on the proximal end side and the distal end side, and are translated by rotation of the rod-shaped member Rd. Therefore, the two translation parts 23, 23 translate equal distances in opposite directions with respect to the rotation of the rod-shaped members 25a, 25b.

As shown in FIG. 2A, the disc-shaped pad 2A is provided on the axially outer end surface of each annular translation portion 23. As shown in FIG. This pad 2A is made of metal and has a tapered shape that expands radially outward toward the corresponding link hub. As shown in FIG. 3, the pad 2A is formed so that the flat surface 2Aa facing the corresponding link hub is maximized.

As shown in FIGS. 6A and 6B, the flat surface 2Aa of the pad 2A is formed to be a plane perpendicular to the central axis of the rod-shaped member Rd. The rotation stopper member 26 includes a rotation stop support part 26a that is integrated into one central link member 17 and projects toward the link center, and a rotation stop support part 26a that extends from the distal end portion of the rotation stop support part 26a to the proximal end side and the distal end side, respectively. It has guide parts 26b, 26b.
The proximal and distal guide portions 26b, 26b of the rotation stopper 26 are made of rods extending a predetermined distance parallel to the central axis of the rod-like member Rd. A through-hole guide hole 2Ab, which is guided by the rod, is formed in a part of each pad 2A in the circumferential direction. The pad 2A may be made of metal such as a friction material, or may be made of non-metal.

Therefore, the rotation of the rod-like member Rd in one direction causes the two translational portions 23, 23 to translate in opposite directions, and the flat surface 2Aa of each pad 2A is moved to the corresponding link hub 12, 13 as shown in FIGS. 12A and 12B. By pressing against the parallel link mechanism 9, the parallel link mechanism 9 is corrected to a predetermined original position as shown in FIG. By rotating the rod-shaped member Rd in the other direction in this state, the flat surface 2Aa (FIG. 6B) of each pad 2A is separated from the corresponding link hub 12, 13.

<Rotary drive source>
As shown in FIG. 3, the link hub 12 on the proximal end side is provided with a rotational drive source Rs that rotationally drives the rod-shaped member Rd together with each of the connecting portions 3 and 4. As shown in FIG. The rotational drive source Rs is a drive source for correcting the original position that rotates the connecting portion 3 on the proximal side of the rod-shaped member Rd around the central axis of the link hub 12 on the proximal side. The rotational drive source Rs is configured to be controllable by a control device Cu (FIG. 1).

The rotational drive source Rs is, for example, a rotary actuator equipped with a deceleration mechanism (not shown), and the drive body of the rotational drive source Rs is fixed to the lower part of the base end support member 12a. The rotational output portion of the rotational drive source Rs is disposed coaxially with the central axis of the link hub 12 on the proximal end side, and is connected to the outer ring OR of the connection portion 3. Therefore, the rod-shaped member Rd and the connecting portions 3, 4 are connected to the link hubs 12, 13 on the proximal end side and the distal end side so as to be rotatably driven around their respective axes.

<Attitude control actuator>
As shown in FIG. 4, the link actuating device 7 includes attitude control actuators 10 in all three sets of link mechanisms 14. The attitude control actuator 10 can be controlled by a control device Cu shown in FIG. Each posture control actuator 10 is a rotary actuator, and is installed on the flange 12aa of the base end support member 12a coaxially with the first rotating shaft 22a. By providing the posture control actuators 10 in at least two of the three sets of link mechanisms 14 shown in FIG. 4, the posture of the distal link hub 13 with respect to the proximal link hub 12 shown in FIG. 1 can be determined. Can be done.

The link actuating device 7 operates the parallel link mechanism 9 by rotationally driving each attitude control actuator 10. Specifically, when the posture control actuator 10 is rotationally driven, the rotation is transmitted to the first rotation shaft 22a. Thereby, the attitude of the link hub 13 on the distal side with respect to the link hub 12 on the proximal side can be arbitrarily changed. An end effector (not shown) is attached to the link hub 13 on the distal end side. Examples of the end effector include a hand including a gripper, a cleaning nozzle, a dispenser, a welding torch, and an image processing device.

<About the control system>
The control device Cu controls the attitude control actuator 10 and the rotational drive source Rs. The control device Cu controls the bending angle θ (FIG. 5) and the turning angle φ (FIG. 5) of the link actuating device 7 by controlling the attitude control actuator 10. Further, the control device Cu performs the origin posture correction work such that the bending angle θ=0 degree and the turning angle φ=0 degree by controlling the rotational drive source Rs. The control device Cu rewritably records, for example, the amount of operation of the attitude control actuator 10 as the origin position in the memory Mr.

<Procedure for correcting origin posture>
7 to 10 show the state in which the posture of the link actuating device is being corrected.
(1) For example, as shown in FIGS. 8A and 8B, with the parallel link mechanism 9 tilted, the rod-shaped member Rd is rotated together with the proximal connecting portion 3 shown in FIG. 9 by the rotational drive source Rs. 9 is a sectional view taken along line IX-IX in FIG. 10.
(2) The rotational movement of the rod-shaped member Rd etc. shown in FIG. Translate toward the side link hubs 12, 13.

(3) Part of the edge of each flat surface 2Aa of the pads 2A, 2A contacts the parallel link center plane of the link hubs 12, 13 on the proximal and distal sides.
(4) After the pads 2A contact each other as shown in FIG. 14, when each pad 2A continues to translate, the plane of the parallel link center side of the link hubs 12, 13 on the proximal and distal sides as shown in FIGS. 11 and 12A. approaches perpendicular to the line segment between the center points of the spherical link.

(5) As shown in FIGS. 12B and 13, when the parallel link center side plane of each link hub 12, 13 is perpendicular to the line segment between the spherical link center points, each flat surface 2Aa of pads 2A, 2A The entirety of the pad 2A contacts the plane of the center side of the parallel link of each link hub 12, 13, and each pad 2A becomes unable to translate. In other words, the correction of the parallel link mechanism 9 to its original position is completed, and the position of the parallel link mechanism 9 is restrained.

<Effect>
According to the link actuating device 7 described above, as shown in FIG. A conversion mechanism 1 is provided that converts the rotational movement of the member Rd into the translational movement of the translational portions 23, 23. When correcting the parallel link mechanism 9 to a predetermined posture, the rotational drive source Rs rotates the rod-like member Rd together with the connecting portions 3 and 4 in a predetermined rotational direction, so that the translational portions 23 and 23 become the rod-like member Rd. Translate along. As a result, the pad 2A provided on each translation portion 23 is translated in a direction approaching the corresponding link hub 12, 13. Finally, the pads 2A, 2A contact the link hubs 12, 13 on the proximal and distal sides, respectively, thereby correcting the parallel link mechanism 9 to a predetermined posture. This improves the inclination rigidity of the link hubs 12 and 13 on the proximal and distal sides, thereby improving the inclination rigidity of the entire parallel link mechanism. By increasing the rigidity of the parallel link mechanism 9 in this way, it is possible to flexibly respond to high-load work, etc., and the versatility of the work can be increased.

The conversion mechanism 1 includes threaded portions 25a and 25b shown in FIG. 6B provided on the outer periphery of the rod-like member Rd, and a translational portion that is a nut portion that is screwed onto the threaded portions 25a and 25b and moves in translation by rotation of the rod-like member Rd. 23, 23. In this case, since the translation portions 23, 23 can be provided near the longitudinal middle of the rod-like member Rd, the pads 2A, 2A can be attached to the corresponding link hubs 12, 13 regardless of the configuration of the link actuating device 7 of FIG. 2A. It is possible to approach or move away from the enemy. For example, even when an end effector is attached to the link hub 13 on the distal end side, the pads 2A, 2A can be freely translated without interfering with the end effector. Therefore, the versatility of the applicable link actuating device 7 can be increased.

The posture correction member is two pads 2A, 2A each having a plane perpendicular to the central axis of the rod-shaped member Rd, and the flat surfaces 2Aa of these pads 2A, 2A are connected to the link hub 12 on the base end side and the distal side, respectively. Contact 13. In this way, by bringing the flat surfaces 2Aa of each pad 2A into contact with the corresponding link hubs 12 and 13, the posture of the parallel link mechanism 9 can be reliably corrected and restrained. Furthermore, by limiting the interference portion of the pad 2A, which is the posture correcting member, with the link hubs 12, 13 to the flat surface 2Aa, it is possible to instantly switch between interference and non-interference.

[Change form]
- A shock absorbing member or a friction reducing member such as an elastic body may be provided on the flat surface 2Aa of each pad 2A. When a shock absorbing member is provided, it is possible to reduce the impact when the pad 2A contacts each link hub 12, 13, and when a friction reducing member is provided, it is possible to suppress wear of parts. As the friction reducing member, for example, a known surface treated member such as diamond-like carbon (DLC) can be applied.
- At least one of the threaded portions 25a, 25b, the proximal and distal guide portions 26b, 26b of the rotation stopper 26, and the through-hole-shaped guide hole 2Ab shown in FIG. It may be provided. When a friction reducing member is used in the sliding part, wear of the sliding part is reduced and the life of the sliding part is extended, and backlash is reduced and positional accuracy is improved.
- The rod-shaped member Rd and each connecting portion 3, 4 shown in FIG. 3 may have a hollow structure that communicates with each other. In this case, the cable of the end effector can be passed through the rod-shaped member Rd and the connecting parts 3 and 4.

Although the embodiments of the present invention have been described above, the embodiments disclosed herein are illustrative in all respects and are not restrictive. The scope of the present invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

DESCRIPTION OF SYMBOLS 1...Conversion mechanism, 2A...Pad (posture correction member), 2Aa...Flat surface (plane), 3, 4...Connection part, 7...Link actuator, 9...Parallel link mechanism, 9a...Proximal side spherical link mechanism , 9b... Spherical link mechanism on the distal end side, 10... Attitude control actuator, 12... Link hub on the proximal end side, 13... Link hub on the distal end side, 14... Link mechanism, 15... End link member on the proximal end side, 16... End link member on the tip side, 17... Central link member, 23... Translation part (nut part), 25a, 25b... Threaded part, Rd... Rod-shaped member, Rs... Rotation drive source, Fs... Feed screw mechanism

Claims (4)

A link hub on the distal side is connected to a link hub on the proximal side so as to be able to change its posture via two or more sets of link mechanisms, and each link mechanism connects the link hub on the proximal side and the link hub on the distal side, respectively. Proximal and distal end link members, one end of which is rotatably connected to the link hub, and a center, both ends of which are rotatably connected to the other ends of these proximal and distal end link members. a parallel link mechanism using a spherical link mechanism having a link member;
A link actuating device comprising: a posture control actuator that is provided in the two or more sets of link mechanisms in this parallel link mechanism and arbitrarily controls the posture of the link hub on the distal end side,
The link hub on the distal side and the link hub on the proximal side are movably connected to each other by a rod-shaped member, and the rod-shaped member connects at least the spherical link center of the spherical link mechanism on the proximal side and the spherical link mechanism on the distal side. A member that passes through the center of the spherical link, and is provided with a connecting portion that connects the rod-shaped member and the link hubs on the proximal end and distal sides, respectively, and is connected to the link hubs on the proximal end and distal sides. , the rod-shaped member and each connecting portion are rotatably connected around their respective axes,
a conversion mechanism that converts rotational movement of the rod-shaped member into translational movement of a translational portion along the rod-shaped member;
a posture correction member that is provided in the translation portion and corrects the parallel link mechanism to a predetermined posture by contacting the link hubs on the proximal end side and the distal side, respectively;
A link actuating device comprising: a rotational drive source that is provided on the link hub on the proximal end side and rotates the rod-shaped member together with each of the connecting portions. 2. The link actuating device according to claim 1, wherein the conversion mechanism includes a threaded portion provided on the outer periphery of the rod-like member, and a nut portion that is screwed onto the threaded portion and moves in translation by rotation of the rod-like member. a link actuator that is a feed screw mechanism having a translation portion; 3. The link actuating device according to claim 1, wherein the posture correction member is two pads each having a plane perpendicular to the central axis of the rod-shaped member, and the plane of these pads is parallel to the base. A link actuator that contacts the end and distal link hubs. The link actuating device according to any one of claims 1 to 3, wherein the rod-shaped member and each connecting portion have a hollow structure that communicates with each other.

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