WO2019138966A1 - Parallel link mechanism and link operation device - Google Patents

Abstract

In a parallel link mechanism (1), a tip-side link hub (3) is connected via three or more link mechanisms (4) to a base-side link hub (2) so as to have a changeable orientation. The link mechanisms (4) each comprise: a base-side end link member (5); a tip-side end link member (6); and a center link member (7). For all of the three or more link mechanisms (4), each base-side arm length (L2A) is the same, and each tip-side arm length (L2B) is also the same. The base-side arm length (L2A) and the tip-side arm length (L2B) are different.

Description

Parallel link mechanism and link actuator Related application

This application claims the priority of Japanese Patent Application No. 2018-001122 filed on Jan. 9, 2018, which is incorporated by reference in its entirety as part of the present application.

The present invention relates to a parallel link mechanism and a link actuating device used for a device requiring a high speed, high accuracy, and a wide operating range such as a medical device or an industrial device.

Patent Document 1 proposes a link actuation device used for various working devices such as medical devices and industrial devices.

U.S. Pat. No. 5,893,296

In the parallel link mechanism used in the link actuating device of Patent Document 1, the end link member on the proximal end side and the end link member on the distal end side have the same arm length for the purpose of sharing parts. You are using However, with this configuration, when the movable range of the parallel link mechanism is increased, in particular, when the maximum bending angle is increased, interference between components is likely to occur. In addition, when the size of the bearing provided in the rotation pair is increased in order to increase the rigidity of the parallel link mechanism, interference between components is likely to occur.

In order to avoid such interference between components, it is necessary to upsize the parallel link mechanism as a whole. However, when the parallel link mechanism is enlarged, a problem arises that high-speed operation can not be performed or the device can not be disposed in a limited space due to a decrease in natural frequency due to an increase in weight on the tip side.

SUMMARY OF THE INVENTION An object of the present invention is to provide a parallel link mechanism having a wide degree of freedom in design and capable of easily changing the design for expanding the movable range, reducing the weight of the tip end, etc.

In the parallel link mechanism according to the present invention, the distal end link hub is changeably connected to the proximal end link hub via three or more sets of link mechanisms, and each link mechanism is the proximal end. The proximal end and distal end end link members, one end of which is rotatably connected to the distal side link hub and the distal end side link hub, and the other end of the proximal and distal end link members And the central link members rotatably connected to each other.

In this parallel link mechanism, a rotation pair shaft of the end link member on the base end side and the central link member, a rotation pair center point of the end link member on the base end side and the link hub on the base end side Is defined as the proximal end side arm length, and further, a rotation pair shaft of the distal end side link member and the central link member, the distal end side link member and the distal side link The distance between the hub and the center of rotation is defined as the tip side arm length.

In this case, in all of the three or more sets of link mechanisms, the arm length on the proximal end side is the same, the arm length on each distal end side is the same, and the arm length on the proximal end side and the arm length on the distal end side are It is different. Here, at each of the proximal end and the distal end, the center of rotation of the end link member and the link hub is an end link along the rotation pair axis in the rotation of the end link member and the link hub. Point to the center point in the width direction of the member.

According to this configuration, in all of the three or more sets of link mechanisms, the arm length on each proximal side is the same, and the arm length on each distal side is also the same. Therefore, even if the proximal end side arm length and the distal end side arm length are different, the parallel link mechanism can operate. By making the proximal end arm length and the distal end arm length different from each other, the design freedom of the parallel link mechanism is improved. This facilitates the design change for expanding the movable range of the parallel link mechanism, reducing the weight of the tip end, and the like.

In the present invention, the distal end side arm length may be shorter than the proximal end arm length. In this case, the components of the parallel link mechanism do not easily interfere with each other, and the movable range can be widened with a compact configuration. In addition, since the tip end side can be reduced in weight, the moment of inertia on the tip end side is reduced, and high speed operation is possible.

In the present invention, at each of the proximal end and the distal end, the end link member is a curved member curved at an arbitrary angle, and fixed to one end or both ends of the curved member, the central link member or the link hub And a rotary shaft supporting member for supporting a rotary shaft rotatably coupled to the rear end directly or through a bearing, wherein the curved member of the proximal end link member and the distal end end link The curved members of the member may be identical to one another. With this configuration, it is possible to realize commonality of parts by the end link member on the proximal end side and the end link member on the distal end side, and an inexpensive configuration can be achieved.

In the present invention, the working body is attached to the distal end member such that at least a portion is positioned in the inner space surrounded by the proximal end link hub, the distal end link hub, and the three or more sets of link mechanisms. A cable connected to the working body may extend proximally through the interior space. With this configuration, the proximal end side portion of the internal space can be widened, so that the cable does not easily interfere with each component of the parallel link mechanism, and cable routing becomes easy. In addition, since the working body is disposed in the internal space, the inertia moment of the working body is smaller than in the case where the working body is disposed closer to the tip side than the link hub on the tip side, and high speed operation is possible. .

　但し、
　Ｒmin：ケーブルの許容最小屈曲半径
　ＬE：先端側の球面リンク中心から作業体のケーブル取付位置までの距離
　ｒc：ケーブルの半径
　Ｄ：基端側および先端側の各球面リンク中心間の距離
　θmax：パラレルリンク機構の最大折れ角
　上記のように定めると、機構上の可動範囲内において、ケーブルの屈曲半径を最小屈曲半径よりも大きく保つことができ、また作業体を内部空間に配置することができる。 When the proximal end link hub has a through hole through which the cable is inserted, the minimum distance Lb from the central axis of the proximal end link hub to the inner wall surface of the through hole is expressed by the following relational expression It is good to meet the conditions.

However,
Rmin: Permissible minimum bending radius of cable LE: Distance from the center of the spherical link on the tip side to the cable mounting position of the working body rc: Radius of the cable D: Distance between the centers of spherical links on the proximal and distal sides θmax: Parallel Maximum bending angle of link mechanism If determined as above, the bending radius of the cable can be kept larger than the minimum bending radius within the mechanical movable range, and the working body can be arranged in the inner space.

Here, the maximum bending angle of the parallel link mechanism is defined as follows. That is, for each of the proximal end and the distal end, the rotation couple shaft of the link hub and the end link member, and the point at which the rotation link shaft of the end link member and the center phosphorus member intersect is the “spherical link center” A straight line passing through the center of the spherical link and intersecting at right angles with the rotational pair of the link hub and the end link member is referred to as "central axis of link hub". In this case, the maximum value of the angle formed by the central axis of the proximal end link hub and the central axis of the distal end link hub is referred to as "the maximum bending angle of the parallel link mechanism".

The link operating device according to the present invention includes the parallel link mechanism, and in the two or more sets of the three or more sets of link mechanisms in the parallel link mechanism, the distal end side with respect to the proximal end link hub An attitude changing drive source is provided which arbitrarily changes the attitude of the link hub.

When the attitude change drive source is provided, attitude control of the parallel link mechanism is possible. By providing the attitude changing drive source in two or more link mechanisms among the three or more link mechanisms, it is possible to determine the attitude of the distal end link hub with respect to the proximal end link hub.

Any combination of the at least two configurations disclosed in the claims and / or the description and / or the drawings is included in the invention. In particular, any combination of two or more of the claims is included in the invention.

The present invention will be more clearly understood from the following description of the preferred embodiments with reference to the attached drawings. However, the embodiments and the drawings are for the purpose of illustration and description only and are not to be taken as limiting the scope of the present invention. The scope of the present invention is defined by the appended claims. In the attached drawings, the same part numbers in multiple drawings indicate the same or corresponding parts.
It is a front view of one state of the parallel link mechanism concerning a 1st embodiment of this invention. It is an II-II arrow line view of Drawing 1 showing the whole end link member by the side of the end face by the section. It is a partial view of FIG. 2A. It is the III-III arrow line view of FIG. 1 which showed the whole edge link member of each front end side in the cross section. It is a partial view of FIG. 3A. It is the figure which expressed one link mechanism of the parallel link mechanism with a straight line. It is the horizontal view which showed the whole end link member of the proximal end of the parallel link mechanism concerning the 2nd Embodiment of this invention in the cross section. It is the horizontal view which showed the whole end link member of each proximal end of the parallel link mechanism concerning the 3rd Embodiment of this invention in the cross section. It is the horizontal view which showed the whole edge part link member of each front end side of the parallel link mechanism in the cross section. It is a front view of one state of the parallel link mechanism concerning a 4th embodiment of this invention. FIG. 9 is a view on arrow IX-IX in FIG. 8 showing the entire end link member on the proximal end side in cross section. FIG. 9 is a cross-sectional view of the end link members on the distal end side, taken along the line XX in FIG. 8; It is a front view of one state of the link operating device concerning a 5th embodiment of this invention. FIG. 12 is a view on arrow XII-XII in FIG. 11 showing the entire end link member on the proximal end side in cross section. It is the elements on larger scale of FIG. 12A. FIG. 13 is a view on arrow XIII-XIII of FIG. 11 showing the entire end link member on each tip side in cross section. It is a horizontal view which shows the different shape of the through-hole of a proximal end member. It is a perspective view which shows the state which attached the working body to the link actuation device shown in FIG. It is a front view showing a part of the link operating device.

Embodiments of the present invention will be described with reference to the drawings.

First Embodiment of Parallel Link Mechanism
FIG. 1 is a front view of one state of a parallel link mechanism according to a first embodiment of the present invention. In the parallel link mechanism 1, the distal end side link hub 3 is connected to the proximal end side link hub 2 via a plurality (for example, three sets) of link mechanisms 4 so as to be changeable in attitude. The number of link mechanisms 4 may be four or more.

Each link mechanism 4 is composed of a proximal end link member 5, a distal end link member 6, and a central link member 7, and constitutes a four-bar linkage consisting of four rotational pairs. There is. One end of the proximal end side end link member 5 is rotatably connected to the proximal end side link hub 2. One end of the end link member 6 on the front end side is rotatably connected to the link hub 3 on the front end side. The other ends of the end link members 5 and 6 on the proximal end side and the distal end side are rotatably connected to both ends of the central link member 7 respectively.

The parallel link mechanism 1 is a structure in which two spherical link mechanisms are combined. In other words, as shown in FIG. 2A, each pair of rotational axes O1A of the proximal end link hub 2 and the proximal end link member 5 and the proximal end link member 5 and the central link member 7 , And each pair of rotation axes O2A intersect at the proximal spherical link center PA. Similarly, as shown in FIG. 3A, the rotational joint shafts O1B of the distal end side link hub 3 and the distal end side link member 6 and the distal end side link member 6 and the central link member 7 The rotational pair axes O2B intersect at the tip end spherical link center PB.

In the example shown in FIG. 2A (FIG. 3A), each rotation couple shaft O1A (O1B) of the link hub 2 (3) and the end link member 5 (6), and the end link member 5 (6) and the central link member 7 And an angle αA (αB) formed by each rotation even axis O2A (O2B) is 90 °. However, the angle αA (αB) may be other than 90 ° (see FIG. 5). In addition, each rotation even axis O2A (O2B) of the end link member 5 (6) and the central link member 7 may have a crossing angle γ (FIG. 1) or may be parallel.

The distance from the spherical link center PA on the proximal side to the rotation center point C1A between the end link member 5 on the proximal side and the central link member 7 (hereinafter referred to as “link length on the proximal side) L1A The distance L1B from the spherical link center PB on the distal end side to each rotation even center point C1B between the end link member 6 on the distal end side and the central link member 7 (hereinafter referred to as “link length on the distal end side) L1B is the same is there.

On the other hand, the distance from the spherical link center PA on the base end side to each rotation pair even center point C2A of the link hub 2 on the base end side and the end link member 5 on the base end side (hereinafter referred to as “arm length on the base end side L2A is the distance from the spherical link center PB on the tip side to each rotation even center point C2B of the link hub 3 on the tip side and the end link member 6 on the tip side (hereinafter, “arm length on the tip side” ) L2B is different. In the case of this embodiment, the arm length L2A on the proximal end side is longer than the arm length L2B on the distal end side. Here, the rotation pair center points C1A, C1B, C2A, C2B indicate center points in the width direction of the end link members 5, 6 along the rotation pair axes O1A, O1B, O2A, O2B in each rotation pair.

In the three sets of link mechanisms 4, the proximal end and the distal end geometrically have the same shape regardless of the posture of the parallel link mechanism 1. The geometrically identical shape is, as shown in FIG. 4, a geometrical model in which each link member 5, 6, 7 is represented by a straight line, that is, represented by each rotational couple and a straight line connecting these rotational pairs. The model is said to have a shape in which the proximal end portion and the distal end portion with respect to the central portion of the central link member 7 are symmetrical. Even if the arm lengths L2A and L2B (FIGS. 2A and 3A) are different on the proximal side and the distal side, if the link lengths L1A and L1B (FIGS. 2A and 3A) are the same on the proximal side and the distal side, Geometrically the same shape. In addition, FIG. 4 is a figure which expressed one set of link mechanism 4 with a straight line.

The parallel link mechanism 1 of this embodiment is a rotationally symmetric type, and includes a proximal end portion including a proximal end link hub 2 and a proximal end link member 5, a distal end link hub 3 and a distal end end. The positional relationship with the tip end portion of the partial link member 6 is rotationally symmetrical with respect to the center line C of the central link member 7. The central portion of each central link member 7 is located on a common orbital circle.

With the link hub 2 on the proximal end side, the link hub 3 on the distal end side, and the three link mechanisms 4, the free end of the link hub 3 on the distal end side with respect to the link hub 2 on the proximal end The degree mechanism is configured. In other words, the link hub 3 on the distal side with respect to the link hub 2 on the proximal side is a mechanism whose attitude can be changed in two degrees of freedom. This two-degree-of-freedom mechanism can widen the movable range of the distal end side link hub 3 with respect to the proximal end side link hub 2 while being compact.

For example, a straight line that passes through the spherical link center PA on the proximal side and intersects at right angles with the rotation couple axes O1A (FIGS. 2A and 3A) of the link hub 2 on the proximal side and the end link member 5 on the proximal side The central axis QA of the link hub 2 on the proximal side is used. Similarly, a straight line passing through the spherical link center PB on the distal end side and intersecting at right angles with the respective rotation couple shafts O1B (FIG. 2A, FIG. 3A) of the link hub 3 on the distal end side and the end link member 6 on the distal end side The central axis QB of the link hub 3 of FIG.

In this case, the maximum value of the bending angle θ between the central axis QA of the proximal link hub 2 and the central axis QB of the distal link hub 3 can be about ± 90 °. Further, the pivot angle φ of the distal end side link hub 3 with respect to the proximal end side link hub 2 can be set in the range of 0 ° to 360 °. The bending angle θ is a vertical angle at which the central axis QB of the distal end link hub 3 is inclined with respect to the central axis QA of the proximal end link hub 2. The pivot angle φ is a horizontal angle at which the central axis QB of the distal end link hub 3 is inclined with respect to the central axis QA of the proximal end link hub 2.

The posture change of the distal end side link hub 3 with respect to the proximal end side link hub 2 is performed with the center of rotation O of the center axis QA of the proximal end side link hub 2 and the central axis QB of the distal end side link hub 3 as a rotation center It will be. FIG. 1 shows a state of an origin position where the central axis QA of the proximal link hub 2 and the central axis QB of the distal link hub 3 are on the same line. Even if the attitude of the distal end side link hub 3 changes, the distances D (FIG. 4) between the proximal end and distal end spherical link centers PA and PB do not change.

When each link mechanism 4 satisfies the following conditions 1 to 5, the proximal end portion including the proximal end link hub 2 and the proximal end link member 5 from the geometric symmetry and the distal end link The distal portion of the hub 3 and the distal end link member 6 move in the same manner. Therefore, the parallel link mechanism 1 functions as a constant velocity universal joint in which the proximal end and the distal end have the same rotation angle and rotate at the same speed when the rotation is transmitted from the proximal end to the distal end.

Condition 1: The angles αA and αB formed by the rotation pair even axes O1A and O1B and the rotation pair even axes O2A and O2B and the link lengths L1A and L1B are equal to one another in each link mechanism 4.
Condition 2: The rotation pair even axes O1A, O1B and the rotation pair even axes O2A, O2B intersect at the spherical link centers PA, PB at the proximal end side and the distal end side.
Condition 3: The geometrical shapes of the proximal end end link member 5 and the distal end side end link member 6 are equal (L1A = L1B).
Condition 4: The geometrical shapes of the proximal end portion and the distal end portion of the central link member 7 are equal.
Condition 5: With respect to the plane of symmetry of the central link member 7, the angular positional relationship between the central link member 7 and the end link members 5 and 6 is the same on the proximal end side and the distal end side.

Each part of the parallel link mechanism 1 will be described in detail. As shown in FIG. 1, FIG. 2A and FIG. 2B, the link hub 2 on the proximal end side has a proximal end member 10 and three rotary shaft connecting members 11 provided integrally with the proximal end member 10. doing. The rotary shaft connecting members 11 are arranged at equal intervals in the circumferential direction around the spherical link center PA on the proximal end side. A rotary shaft 12 whose axial center coincides with the rotary paired shaft O1A is rotatably connected to each rotary shaft connecting member 11 via two bearings 13. One end of a proximal end side end link member 5 is connected to the rotary shaft 12. Thus, one end of the end link member 5 on the base end side with respect to the rotation shaft connection member 11 is rotatably connected around the rotation couple shaft O1A.

The bearing 13 is, for example, a ball bearing such as a deep groove ball bearing or an angular ball bearing. Each bearing 13 is installed in a fitted state in the rotary shaft connecting member 11, and is fixed by a method such as press fitting, bonding, or caulking. The types and installation methods of the bearings 15, 43 and 45 provided in the other rotation pair are also the same.

At one end of the central link member 7, a rotation shaft 14 whose axis coincides with the rotation couple shaft O 2 A is rotatably connected via two bearings 15. The other end of the end link member 5 on the proximal end side is connected to the rotation shaft 14. Thus, one end of the central link member 7 is rotatably coupled to the other end of the proximal end side end link member 5 around the rotation couple shaft O2A.

FIG. 2B shows one proximal end link member 5 and the periphery of both ends thereof. As shown in the figure, the end link member 5 on the base end side has one proximal end curved member 20A curved in an L-shape and the outer diameter side of one end of the proximal end curved member 20A. Are fixed to the outer diameter side and the inner diameter side of the other end of the two proximal end rotary shaft support members 21A fixed respectively to the side surface and the inner diameter side of the And two rotary shaft support members 31A on the base end side.

The rotary shaft support members 21A, 31A on the proximal end side are fixed to the bending member 20A by bolts, welding or the like. In FIG. 2B, means for positioning the rotary shaft supporting members 21A and 31A on the proximal end side with respect to the bending member 20A on the proximal end side is not shown, but for example, the bending member on the proximal end side using positioning pins etc. The rotary shaft support members 21A and 31A on the proximal side may be positioned with respect to 20A.

The bending member 20A on the proximal end side is, for example, a cast product of a metal material, and has a shape curved at a predetermined angle αA (90 ° in this example). The rotary shaft support members 21A and 31A on the base end side are formed in a predetermined shape by processing a plate-like member such as a metal plate having a constant thickness by processing such as sheet metal processing. The rotary shaft support members 21A and 31A on the base end side are provided with through holes through which the rotary shafts 12 and 14 are inserted.

Specifically, the rotation pair of the link hub 2 on the proximal side and the end link member 5 on the proximal side has the following structure. That is, the rotary shaft connecting member 11 is disposed between the rotary shaft support members 21A on the two proximal ends of the end link member 5 on the proximal end side. The rotary shaft 12 is inserted through the through hole of the rotary shaft support member 21A on the base end side of the outer diameter side, the hole of the inner ring of the bearing 13 and the through hole of the rotary shaft support member 21A on the inner diameter side. A nut 23 is screwed to the screw portion 12a of the rotary shaft 12 projecting to the side.

Spacers 24 and 25 are interposed between the rotary shaft support member 21A on the inner diameter side and the bearing 13, and between the rotary shaft support member 21 and the bearing 13 on the outer diameter side. There is. As described above, the rotary shaft support member 21A on the outer diameter side and the base end side on the inner diameter side, the inner ring of the bearing 13, and the spacers 24 and 25 are held by the head 12b of the rotary shaft 12 and the nut 23. . Thereby, in a state where preload is applied to the bearing 13, the rotary shaft connecting member 11 and one end of the end link member 5 on the base end side are connected.

Specifically, the rotation pair of the other end of the end link member 5 on the proximal end side and the central link member 7 has the following structure. That is, one end of the central link member 7 is disposed between the two rotary shaft support members 31A of the end link member 5 on the proximal end side. The rotary shaft 14 is inserted through the through hole of the rotary shaft support member 31A on the base end side of the outer diameter side, the hole of the inner ring of the bearing 15, and the through hole of the rotary shaft support member 31A on the inner diameter side A nut 33 is screwed on a threaded portion 14 a of the rotary shaft 14 which protrudes to the inner diameter side of the hole.

Spacers 34 and 35 are interposed between the rotary shaft support member 31A and the bearing 15 on the proximal end side of the inner diameter side and between the rotary shaft support member 31A and the bearing 15 on the proximal end side of the outer diameter side, respectively. There is. Thus, the rotary shaft support member 31A on the outer diameter side and the base end side on the inner diameter side, the inner ring of the bearing 15, and the spacers 34, 35 are held between the head 14b of the rotary shaft 14 and the nut 33. . Thereby, the other end of the end link member 5 on the proximal end side and one end of the central link member 7 are connected in a state in which the preload is applied to the bearing 15.

As shown in FIG. 1, FIG. 3A and FIG. 3B, the link hub 3 on the distal end side has a distal end member 40 and three rotary shaft connecting members 41 integrally provided with the distal end member 40. . The rotary shaft connection members 41 are arranged at equal intervals in the circumferential direction around the spherical link center PB on the tip side. A rotary shaft 42 whose axis is coincident with the rotation paired shaft O1B is rotatably connected to each rotary shaft connecting member 41 via two bearings 43. One end of an end link member 6 on the tip end side is connected to the rotation shaft 42. Thereby, one end of the end link member 6 on the tip end side with respect to the rotation shaft connection member 41 is rotatably connected around the rotation couple shaft O1B.

At the other end of the central link member 7, a rotation shaft 44 whose axis coincides with the rotation couple shaft O2B is rotatably connected via two bearings 45. The other end of the end link member 6 on the tip end side is connected to the rotation shaft 44. Thus, the other end of the central link member 7 is rotatably connected to the other end of the end link member 6 on the distal end side around the rotation couple shaft O2B.

One end side end link member 6 and its both-ends periphery part are shown to FIG. 3B. As shown in the figure, the end link member 6 on the distal end side has one L-shaped curved member 20B on the distal end side, an outer diameter side of one end of the curved member 20B on the distal end, and a side surface Two tip side rotation shaft support members 21B fixed to the side surface on the inside diameter side and two side surfaces fixed to the side surface on the outside diameter side and the side surface on the inside diameter side of the other end of the bending member 20B on the tip side And a rotary shaft support member 31B on the tip side.

The rotary shaft support members 21B and 31B on the distal end side are fixed to the curved member 20B on the distal end side by bolts, welding or the like. Although the means for positioning the rotary shaft support members 21B and 31B on the distal end side with respect to the distal end side curved member 20B is not shown in FIG. 3B, for example, with respect to the distal end side curved member 20B using a positioning pin or the like. The rotary shaft support members 21B and 31B on the distal end side may be positioned.

The bending member 20B on the distal end side is also a cast product of, for example, a metal material, similarly to the bending member 20A on the base end side, and has a curved shape at a predetermined angle αB (90 ° in this example). According to the difference between the proximal end and distal end arm lengths L2A and L2B, the length M2B from the curved portion of the distal end curved member 20B to the other end is the length from the curved portion of the proximal end curved member 20A It is formed shorter than the length M2A to the end. The lengths M1A and M1B from the bending portion to one end are the same for the bending member 20B on the distal end side and the bending member 20A on the base end side.

The rotary shaft support members 21B and 31B on the distal end side perform processing such as sheet metal processing on a plate-like member having a constant thickness such as a metal plate, similarly to the rotary shaft support members 21A and 31A on the proximal end side. Is formed in a predetermined shape. Through-holes 22 and 32 through which the rotary shafts 42 and 44 are inserted are provided in the rotary shaft support members 21B and 31B on the distal end side.

The rotational pair of the distal end side link hub 3 and the distal end side link member 6 has the same structure as the rotational pair of the proximal end link hub 2 and the proximal end end link member 5. Further, the rotation pair of the end link member 6 on the distal end side and the central link member 7 has the same structure as the rotation pair of the end link member 5 on the base end side and the central link member 7. Therefore, the description is omitted for each rotation pair even section on the distal end side, and the same reference numeral as the rotation pair even numbered on the base end side is shown in the drawing about the same structure as the base end side. The rotating shaft 42 has a threaded portion 42a and a large diameter portion 42b, and the rotating shaft 44 has a threaded portion 44a and a large diameter portion 44b.

As described above, in the parallel link mechanism 1, the proximal end side arm length L2A and the distal end side arm length L2B are different. As a result, the degree of freedom in design is improved, and design change for expanding the movable range, reducing the weight on the tip end, and the like is easy. Even if the proximal end side arm length L2A and the distal end side arm length L2B are different, if the proximal end side and the distal end side are geometrically the same shape, the distal end with respect to the proximal end link hub 2 A two-degree-of-freedom mechanism capable of changing the attitude of the side link hub 3 with two degrees of freedom is configured.

As in this embodiment, when the distal end side arm length L2B is shorter than the proximal end side arm length L2A, the components of the parallel link mechanism 1 are less likely to interfere with each other, and the movable range is wide with a compact configuration. It can be taken. In addition, since the tip end side can be reduced in weight, the moment of inertia on the tip end side is reduced, and high speed operation is possible.

Further, in this embodiment, the end link members 5 and 6 at the proximal end and the distal end include the bending members 20A and 20B at the proximal end and the distal end, and the rotary shaft support members 21A at the proximal end and the distal end, 21B, 31A, and 31B. As described above, when the end link members 5 and 6 on the proximal end side and the distal end side are divided into a plurality of members, each member can be formed into a simple shape, so processing costs can be suppressed and mass productivity can be improved. . Also, at the time of assembly, the proximal and distal end link members 5 and 6 and the central link member 7 are in rotational pairs, or the proximal and distal end link members 5 and 6 and the proximal end and The parts (bearings, spacers, etc.) constituting the rotational joint with the distal end side link hubs 2 and 3 can be inserted into the rotational shaft from one direction, and the assemblability is improved.

Furthermore, by supporting both ends of the rotary shafts 12, 14, 42 and 44 by two rotary shaft support members 21A, 21B, 31A, 31B in each rotary pair, the rigidity against the moment load of the rotary pair becomes high. The overall rigidity of the parallel link mechanism 1 is improved. If the rotary shaft support members 21A, 21B, 31A, and 31B have the same shape, parts can be made common, inexpensive, and mass productivity can be improved.

Second Embodiment of Parallel Link Mechanism
FIG. 5 shows the rotational pair shafts O1A of the proximal end link hub 2 and the proximal end link member 5, and the rotational pair shafts of the proximal end link member 5 and the center link member 7. An example is shown in which the angle αA formed by O 2 A mutually is other than 90 °. Although illustration is omitted about the tip side, each rotation couple shaft of the tip side link hub and the tip side end link member, and each rotation pair of the tip side end link member and the center link member 7 The angle αB (not shown) that the axes make with one another is also as large as the angle αA on the proximal side. As described above, even if the angles αA and αB are other than 90 °, if the proximal end and the distal end are geometrically the same shape, the link hub on the distal end side with respect to the link hub 2 on the proximal end is A two-degree-of-freedom mechanism capable of attitude change with two degrees of freedom is configured.

[Third Embodiment of Parallel Link Mechanism]
6 and 7 show parallel link mechanisms in which the configurations of the end link members 5 and 6 on the proximal and distal sides are different from those of the first embodiment described above. The overall configuration of this parallel link mechanism is the same as that of the first embodiment, so the drawing and description of the overall configuration will be omitted.

In this parallel link mechanism, the proximal curved member 20A used for the proximal end end link member 5 and the distal curved member 20B used for the distal end link member 6 have the same specifications. is there. By changing the fixing positions of the rotary shaft support members 21A, 21B, 31A, 31B on the proximal and distal sides with respect to the curved members 20A and 20B on the proximal and distal sides, end links on the proximal and distal sides The arm lengths L2A and L2B of the members 5 and 6 are respectively set to predetermined lengths. By using the base end side and the tip end side curved members 20A and 20B of the same specification as described above, parts can be made common, and the parallel link mechanism can be manufactured inexpensively.

[Fourth Embodiment of Parallel Link Mechanism]
FIG. 8 is a front view of one state of a parallel link mechanism according to a fourth embodiment of the present invention. In the parallel link mechanism 1, the arm length L <b> 2 </ b> B on the distal end side is longer than the arm length L <b> 2 </ b> A on the proximal end, contrary to the first embodiment. As shown in FIGS. 9 and 10, even if the arm lengths L2A and L2B are different between the proximal end and the distal end, the link lengths L1A and L1B at the proximal end and the distal end are the same.

As described above, when the arm length L2B on the distal end side is made longer than the arm length L2A on the proximal end side, the distal end member 40 can be provided with a large through hole 40a. Thereby, a large working body (not shown) can be inserted from the through hole 40 a and arranged in the internal space 8 of the parallel link mechanism 1. The internal space 8 is a space surrounded by the link hubs 2 and 3 on the proximal end side and the distal end side and each link mechanism 4.

[Link operating device (fifth embodiment)]
11 to 13 show a link actuation device provided with the parallel link mechanism of the first embodiment. In the link actuation device 50, each link mechanism 4 of the parallel link mechanism 1 is provided with an attitude changing drive source 51 for arbitrarily changing the attitude of the distal end side link hub 3 with respect to the proximal end side link hub 2. . In the example shown in the figure, the attitude changing drive source 51 is provided for all three link mechanisms 4, but if at least two sets of attitude control drive sources 51 are provided among the three link mechanisms 4, the base end The attitude of the distal end side link hub 3 with respect to the side link hub 2 can be determined.

Each attitude control drive source 51 is a rotary actuator provided with a reduction mechanism 52, and is installed coaxially with the rotation shaft 12 on the upper surface of the base end member 10 of the link hub 2 on the base end side. The attitude control drive source 51 and the reduction mechanism 52 are integrally provided, and the reduction mechanism 52 is fixed to the base end member 10 by the drive source fixing member 53.

In FIG. 12B, the rotational output decelerated by the reduction mechanism 52 is output to the output shaft 54 which includes the large diameter base 54 a and the small diameter tip 54 b. The tip 54 b of the output shaft 54 corresponds to the rotation shaft 12 in the parallel link mechanism 1. The distal end surface of the base 54a of the output shaft 54 is in contact with the rotary shaft support member 21A on the outer diameter side of the end link member 5 on the proximal end side, and the base 54a is coupled to the rotary shaft support member 21A by the bolt 55 There is.

In the link actuation device 50, the parallel link mechanism 1 operates by rotationally driving each attitude control drive source 51. Specifically, when the attitude control drive source 51 is rotationally driven, the rotation is decelerated via the reduction mechanism 52 and transmitted to the rotating shaft 12. Thereby, the angle of the end link member 5 on the proximal side with respect to the link hub 2 on the proximal side is changed, and the posture of the link hub 3 on the distal side with respect to the link hub 2 on the proximal side is changed. By attaching the working body (end effector) to the link hub 3 on the tip side, work can be performed while arbitrarily changing the posture of the working body.

As shown in FIG. 12A, in the central portion of the proximal end member 10 of the link hub 2 on the proximal end side, a through hole 10a for passing a cable such as an electrical wiring connected to a working body attached to the link hub 3 on the distal end side is provided. It is done. Further, as shown in FIG. 13, a through hole 40 a for fitting and attaching a working body is provided at the center of the tip end member 40 of the link hub 3 on the tip end side. In the examples of FIGS. 12A, 12B, and 13, the through holes 10a and 40a are substantially square centered on the central axes QA and QB of the link hubs 2 and 3 on the proximal end side and the distal end side, respectively. For example, as shown in FIG. 14, the through holes 10a and 40a may have other shapes.

FIG. 15 shows a state in which the working body 60 is attached to the link hub 3 on the tip side of the link actuation device 50. The working body 60 is fitted in and attached to the through hole 40 a (see FIG. 12A) of the tip member 40, and most of the working body 60 is disposed in the internal space 8 of the parallel link mechanism 1. A cable 61 connected to the working body 60 extends to the outside of the link actuation device 50 through the internal space 8 and the through hole 10 a of the proximal member 10.

Thus, when attaching the wired working body 60 to the distal end side link hub 3, it is necessary to design so that the bending radius of the cable 61 does not exceed the allowable value within the operation range of the parallel link mechanism 1. Specifically, the minimum distance Lb from the central axis QA of the link hub 2 on the proximal end to the inner wall surface of the through hole 10a is appropriately set so that the cable 61 does not contact the inner wall surface of the through hole 10a of the proximal member 10 Determined in The minimum distance Lb is the radius of the inscribed circle of the through hole 10a even when the through hole 10a is square as shown in FIG. 12A and when the through hole 10a has a shape other than square as shown in FIG.

　但し、
　Ｒmin：ケーブル６１の許容最小屈曲半径
　ＬE：先端側の球面リンク中心ＰＢから作業体６０のケーブル取付位置までの距離
　ｒc：ケーブル６１の半径
　Ｄ：基端側および先端側の各球面リンク中心ＰＡ，ＰＢ間の距離
　θmax：パラレルリンク機構１の最大折れ角 When the dimensions of each part are determined as shown in FIG. 16, the minimum distance Lb from the central axis QA of the link hub 2 on the proximal end side to the inner wall surface of the through hole 10a satisfies the condition of the following relational expression The shape of the through hole 10a may be designed.

However,
Rmin: Permissible minimum bending radius of the cable 61 LE: Distance from the spherical link center PB on the tip side to the cable mounting position of the working body 60 rc: Radius of the cable 61 D: Spherical link centers PA on the proximal and distal sides Distance between PB θmax: Maximum bending angle of parallel link mechanism 1

The reasons are described below. When considered in the horizontal direction of FIG. 16, the horizontal distance from the spherical link center PB on the distal end side to the inner wall surface of the through hole 10a of the proximal member 10 is the cable 61 of the working body 60 from the spherical link center PB on the distal end side. If it is larger than the horizontal distance to the end face, the cable 61 can be taken out from the through hole 10a through the internal space 8 (FIG. 15) of the parallel link mechanism 1 while keeping the bending radius of the cable 61 within the allowable value.

で表すことができる。
　また、先端側の球面リンク中心ＰＢから作業体６０のケーブル６１の端面までの水平距離は、ＬE・sinθmax＋Ｒmin（１・cosθmax）＋ｒcで表すことができる。 The horizontal distance from the distal end side spherical link center PB to the inner wall surface of the through hole 10a of the proximal member 10 is Lb + Lpsin θmax, ie,

Can be represented by
Further, the horizontal distance from the spherical link center PB on the tip side to the end face of the cable 61 of the working body 60 can be expressed by LE · sin θmax + Rmin (1 · cos θmax) + rc.

From these, the cable 61 does not contact the inner wall surface of the through hole 10 a of the proximal member 10 within the operation range of the parallel link mechanism 1 as having the shape of the through hole 10 a satisfying Expression 1. In other words, the distance LE from the spherical link center PB on the tip side to the cable attachment position of the working body 60 can be increased within the range satisfying the equation (1). That is, the working body 60 can be attached to the distal end side link hub 3 so that a large portion of the working body 60 is located in the internal space 8. As a result, compared with the case where the working body 60 is disposed closer to the tip end than the link hub 3 on the tip end side, the inertia moment of the working body 60 can be reduced, and the movable range of the parallel link mechanism 1 can be enlarged. .

As described above, although the preferred embodiments have been described with reference to the drawings, the present invention is not limited to the above embodiments, and various additions and modifications can be made without departing from the scope of the present invention. Or can be deleted. Therefore, such is also included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Parallel link mechanism 2 ... Link hub 3 of proximal end side ... Link hub 4 of front end side Link mechanism 5 ... End part link member 6 of proximal end side ... End part link member 7 of front end side ... Central link member 8 ... Internal space 12, 14, 42, 44 ... Rotating shaft 13, 15, 43, 45 ... Bearing 20A ... Bending member 20B on the base end side ... Bending member 21A, 31A on the tip side ... Rotating shaft support member 21 B on the base end side 31B: Rotary shaft supporting members 10a, 40a on the tip side: through holes 50: link operating device 51: drive source for attitude control 60: working body 61: cable C2A: end link member on the base end and link on the base end Rotation pair center point C2B with the hub ... Rotation pair center point L2A of the end link member on the tip side and the link hub on the tip side ... Arm length L2B on the base end ... Arm length O1A on the tip side ... Link on the base end Hub and proximal end link Rotational pair shaft O1B with ... Rotational pair shaft O2A of the end side link member with center link member O2B ... Rotation of the end link member of the end side link member with the end side link member of the end side link member O2B ... end of the end side Pair of rotating shafts of head link member and center link member

Claims (6)

A distal end link hub is changeably connected to the proximal end link hub via three or more sets of link mechanisms, and each link mechanism includes the proximal end link hub and the distal end side A proximal end and a distal end end link member whose one end is rotatably connected to the link hub and a center where both ends are rotatably coupled to the other end of the proximal end and the distal end side end link member In a parallel link mechanism provided with a link member,
The distance between the rotation pair shaft of the end link member on the proximal end side and the central link member, and the rotation center point of the rotation pair even between the end link member on the proximal end side and the link hub on the proximal end is It is defined as a side arm length, and further, a rotation couple shaft of the end link member on the tip side and the central link member, a rotation couple center point of the end link member on the tip side and the link hub on the tip side If we define the distance between and the arm length on the tip side,
In all the three or more sets of link mechanisms, the arm length on each proximal side is the same, the arm length on each distal side is the same, and the arm length on the proximal side is different from the arm length on the distal side Parallel link mechanism. The parallel link mechanism according to claim 1, wherein the arm length on the distal end side is shorter than the arm length on the proximal end side. The parallel link mechanism according to claim 1 or 2, wherein the proximal end link member is a proximal bending member curved at an arbitrary angle, one end of the proximal bending member, or the other bending member. A proximal rotation shaft support member fixed to both ends and supporting a rotary shaft rotatably coupled to the central link member or the proximal link hub directly or through a bearing;
The distal end link member is fixed to the distal end curved member bent at an arbitrary angle, and to one end or both ends of the distal end curved member, and directly to the central link member or the distal end link hub Or a tip side rotation shaft support member for supporting a rotation shaft rotatably coupled via a bearing,
The parallel link mechanism in which the curved member on the proximal end side and the curved member on the distal end side have the same specifications. The parallel link mechanism according to any one of claims 1 to 3, wherein the proximal end side link hub, the distal end side link hub, and an internal space surrounded by the three or more sets of link mechanisms. A working body is attached to the tip member such that at least a portion is located,
A parallel link mechanism in which a cable connected to the working body extends proximally through the internal space. 5. The parallel link mechanism according to claim 4, wherein the proximal end link hub has a through hole through which the cable is inserted, and the central axis of the proximal end link hub to the inner wall surface of the through hole Parallel link mechanism in which the minimum distance Lb satisfies the following relational expression.

However,
Rmin: Permissible minimum bending radius of cable LE: Distance from the center of the spherical link on the tip side to the cable mounting position of the working body rc: Radius of the cable D: Distance between the centers of spherical links on the proximal and distal sides θmax: Parallel Maximum bending angle of link mechanism A parallel link mechanism according to any one of claims 1 to 5, comprising:
An attitude changing drive source for arbitrarily changing the attitude of the distal end side link hub with respect to the proximal end side link hub is provided in two or more of the three or more sets of link mechanisms in the parallel link mechanism. Link actuator provided.

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