Parallel link mechanism and method of assembling the same

Abstract

To provide a parallel link mechanism capable of improving assemblability, and an assembling method thereof.SOLUTION: Each of the proximal-side link hub 5 and the distal-side link hub 4 of the parallel link mechanism 2 includes a plurality of hub constituent members 11, and a coupling plate HP that is a hub coupling member for coupling the hub constituent members 11. Each hub constituting member 11 has a revolute pair part for rotatably connecting the end part link member, and a connecting part for fixing the adjacent hub constituting members to each other by a hub connecting member. A positioning part 21 is provided on the hub constituting members 1111 and on the base end side and the tip side or the end part link member.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a parallel link mechanism used in equipment requiring precision and a wide operating range, such as medical equipment or industrial equipment, and to an assembly method thereof. [Background technology]

[0002] Parallel link mechanisms have been proposed in the past (Patent Documents 1 and 2). A parallel link mechanism is a mechanism in which a base-end hub and a tip-end hub are connected by multiple link systems, and the link systems are often arranged radially from the center. When assembling a parallel link mechanism, it is necessary to connect the connecting parts at the ends of the multiple link systems to the hubs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-94245 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-194207 Summary of the Invention [Problem to be solved by the invention]

[0004] The linkages and hubs are not properly positioned during assembly, making assembly difficult. Specifically, if the parts are not in the correct position, the screws to be fastened cannot be inserted and connected. The parallel links and hubs are positioned at different angles to each other, and can freely change position during assembly, but they must be held in place to prevent them from falling due to gravity.

[0005] An object of the present invention is to provide a parallel link mechanism and an assembly method thereof that can improve assembly efficiency. [Means for solving the problem]

[0006] In the parallel link mechanism of the present invention, a tip-side link hub is connected to a base-side link hub via two or more sets of link mechanisms so that its posture can be changed, and each of the link mechanisms uses a spherical link mechanism having a base-side link member, a central link member, and a tip-side link member; a parallel link mechanism in which one end of the base-end link member is coupled to the base-end link hub rotatably about a first rotation axis, and one end of the tip-end link member is coupled to the tip-end link hub rotatably about a second rotation axis, the base end link hub and the tip end link hub each include a plurality of hub components and a hub connecting member that connects these hub components; Each of the hub components has a revolute pair that rotatably connects the base-end link member or the tip-end link member, and a connecting portion that fixes adjacent hub components to each other with the hub connecting member, Regarding a unit including the base end side hub component, the base end side link member, the central link member, the tip end side link member and the tip end side hub component, and in which adjacent members are connected to each other, The hub component members on the proximal and distal sides, or the end link members that are the proximal and distal link members, have positioning portions provided thereon.

[0007] According to this configuration, a base-end link hub, a tip-end link hub, and two or more sets of link mechanisms can form a mechanism in which the tip-end link hub has two degrees of freedom of rotation relative to the base-end link hub and can freely change its posture. Positioning portions are provided on the base-end and tip-end hub components, or on the end link members that are the base-end and tip-end link members. These positioning portions are configured to be able to constrain the pair of first and second rotation shafts in the unit. By forming the unit as described above, it becomes easier to attach and assemble the parts inside the parallel link. This improves maintainability by replacing the units. By constraining the posture of each unit with the positioning portions, it becomes easier to assemble the parallel link mechanism without undesired movement. In addition, the unit becomes easier to store and transport.

[0008] The positioning portion can constrain the first rotation shaft of the hub component member on the base end side and the second rotation shaft of the hub component member on the tip end side of the unit so that they cannot rotate. In this case, the orientation of each unit is further constrained, making it easier to align the units with each other. This can further improve the ease of assembly of the parallel link mechanism.

[0009] The method for assembling a parallel link mechanism of the present invention is a method for assembling a parallel link mechanism using a spherical link mechanism in which a tip-side link hub is connected to a base-side link hub via two or more sets of link mechanisms so that its posture can be changed, and each of the link mechanisms has, in order, a base-side link member, a central link member, and a tip-side link member, the base end link hub and the tip end link hub each include a plurality of hub components and a hub connecting member that connects these hub components; a unit assembling process for assembling a unit including the base-end hub component, the base-end link member, the central link member, the tip-end link member, and the tip-end hub component; a link restraining step of restraining the posture of the link mechanism of one of the units using a positioning member; and a fixing step of fixing the plurality of hub constituent members by the hub connecting member.

[0010] According to this assembly method, the units are assembled in the unit assembly process, and the position of the link mechanism of one unit is constrained using a positioning member in the link constraining process. Then, in the fixing process, multiple hub components are fixed with hub connecting members. In particular, by constraining the position of the link mechanism of one unit using a positioning member, the link mechanism does not move, making it easier to connect units to each other.

[0011] The link actuation device of the present invention is provided with an attitude control actuator that arbitrarily controls the attitude of the tip-side link hub in each of the two or more link mechanisms in any of the parallel link mechanisms of the present invention. Therefore, the effects described above for the parallel link mechanism of the present invention can be obtained. The provision of the attitude control actuator makes it possible to determine the attitude of the tip-side link hub relative to the base-side link hub. Combining the attitude control actuator with the parallel link mechanism enables precise, wide-range, high-speed operation, resulting in a lightweight, compact link actuation device. [Effects of the Invention]

[0012] By dividing the parallel link mechanism of the present invention into the above units, it becomes easier to attach and assemble the parts inside the parallel links. Maintenance can be improved by replacing the units. By restraining the posture of each unit using the positioning parts, the parallel link mechanism can be assembled easily without undesired movement. Furthermore, the units can be easily stored and transported. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view of a link actuator including a parallel link mechanism according to a first embodiment of the present invention. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. 2 is a perspective view of a hub component member of the parallel link mechanism. [Figure 5] FIG. 2 is a perspective view of a link hub of the parallel link mechanism. [Figure 6] FIG. [Figure 7] FIG. 2 is a perspective view of one unit of the parallel link mechanism. [Figure 8] FIG. [Figure 9] FIG. [Figure 10]FIG. 10 is a perspective view of a link actuation device including a parallel link mechanism according to a second embodiment of the present invention. [Figure 11] FIG. [Figure 12] FIG. 2 is a plan view of the link actuator. [Figure 13] FIG. 2 is a perspective view of a hub component member on the base end side of the parallel link mechanism. [Figure 14] FIG. 2 is a perspective view of a hub component member on the tip side of the parallel link mechanism. [Figure 15] FIG. 2 is a perspective view of a base-end link hub of the parallel link mechanism. [Figure 16] FIG. 2 is a perspective view of a tip-side link hub of the parallel link mechanism. [Figure 17] FIG. 2 is a perspective view of one unit of the parallel link mechanism. [Figure 18] FIG. 10 is a perspective view of a parallel link mechanism according to a third embodiment of the present invention. [Figure 19] FIG. 2 is a front view of the parallel link mechanism. [Figure 20] FIG. 2 is a plan view of the parallel link mechanism. [Figure 21] FIG. 2 is a perspective view of a hub component member of the parallel link mechanism. [Figure 22] FIG. 2 is a perspective view of a link hub of the parallel link mechanism. [Figure 23] FIG. 2 is a perspective view of one unit of the parallel link mechanism. [Figure 24] FIG. [Figure 25] FIG. 2 is a front view of a positioning member used in the unit. DETAILED DESCRIPTION OF THE INVENTION

[0014] [First embodiment] A parallel link mechanism and a link actuation device including this parallel link mechanism according to an embodiment of the present invention will be described with reference to FIGS. 1 to 9. FIG.

[0015] <Outline of the structure of the link actuator> 1, the link actuation device 1 includes a parallel link mechanism 2, an attitude control actuator 3 that arbitrarily controls the attitude of the parallel link mechanism 2, and a control device Cu. The link actuation device 1 is used, for example, in medical equipment or industrial equipment. The link actuation device 1 performs work by positioning an end effector (not shown) attached to a distal end link hub 4 (described later) with respect to a workpiece (not shown).

[0016] <Parallel link mechanism> As shown in Figure 2, the parallel link mechanism 2 has a tip-side link hub 4 connected to a base-side link hub 5 via three link mechanisms 6 so that its posture can be changed. The number of link mechanisms 6 may be two, four or more. The parallel link mechanism 2 is configured so that it can be traded independently in the market.

[0017] Each link mechanism 6 includes a base-side link member 7, a central link member 8, and a distal-side link member 9, forming a four-bar link mechanism with four revolute pairs. One end of the base-side link member 7 is connected to the base-side link hub 5 so as to be rotatable about a first rotation axis 10a. As shown in FIG. 3, one end of the distal-side link member 9 is connected to the distal-side link hub 4 so as to be rotatable about a second rotation axis 10b. As shown in FIG. 2, one end of the central link member 8 is connected to the other end of the base-side link member 7 so as to be rotatable about a third rotation axis 10c, and the other end of the central link member 8 is connected to the other end of the distal-side link member 9 so as to be rotatable about a fourth rotation axis 10d. Hereinafter, the base-side link member 7 and the distal-side link member 9 may be collectively referred to as "end link members." The base-side link hub 5 and the distal-side link hub 4 may be collectively referred to as "link hubs."

[0018] The first rotation axis 10a is a rotation axis around the central axis of each rotation pair between the base end link hub 5 and the base end link member 7, and the second rotation axis 10b is a rotation axis around the central axis of each rotation pair between the tip end link hub 4 and the tip end link member 9. The third rotation axis 10c is a rotation axis around the central axis of each rotation pair between the base end link member 7 and the central link member 8, and the fourth rotation axis 10d is a rotation axis around the central axis of each rotation pair between the tip end link member 9 and the central link member 8.

[0019] The parallel link mechanism 2 is a combination of two spherical link mechanisms 2a and 2b. Each rotational pair between the base-end link member 7 and the central link member 8 moves on a moving spherical surface, which is a spherical surface centered on the base-end spherical link center PA. Each rotational pair between the tip-end link member 9 and the central link member 8 moves on a moving spherical surface, which is a spherical surface centered on the tip-end spherical link center PB.

[0020] In the base-side first spherical link mechanism 2a, the central axis QA of the base-side link hub 5 and the central axes of the first and third rotating shafts 10a, 10c intersect at the base-side spherical link center PA. In the tip-side second spherical link mechanism 2b, the central axis QB of the tip-side link hub 4 and the central axes of the second and fourth rotating shafts 10b, 10d intersect at the tip-side spherical link center PB. In this embodiment, the distance between the center of each rotation pair between the base-side link hub 5 and the base-side link member 7 and the center PA of the base-side spherical link is the same. The distance between the center of each rotation pair between the base-side link member 7 and the central link member 8 and the center PA of the base-side spherical link is the same.

[0021] Similarly, the distance between the center of each rotation pair between the tip side link hub 4 and the tip side link member 9 and the center PB of the tip side spherical link is the same. The distance between the center of each rotation pair between the tip side link member 9 and the central link member 8 and the center PB of the tip side spherical link is the same, but may be different. The third and fourth rotating shafts 10c, 10d have a certain crossing angle (also called the "shaft angle"), but may be parallel. The arm angle, which is the angle formed by the first rotating shaft 10a and the third rotating shaft 10c, is set to a predetermined angle.

[0022] The three link mechanisms 6 have the same geometric shape. In other words, the geometric model in which each link member 7, 8, 9 is expressed by a straight line, i.e., the model expressed by each rotation pair and the straight lines connecting these rotation pairs, has a shape in which the base end portion and the tip end portion with respect to the center of the central link member 8 are symmetrical, regardless of the posture. The parallel link mechanism 2 is configured so that the positional relationship between the base end link hub 5 and base end link member 7 and the tip end link hub 4 and tip end link member 9 is rotationally symmetrical about the center line of the central link member 8.

[0023] The base end link hub 5, the tip end link hub 4, and three sets of link mechanisms 6 form a mechanism that allows the tip end link hub 4 to rotate with two degrees of freedom and freely change its position relative to the base end link hub 5. This two-degrees-of-freedom mechanism is compact, yet allows the tip end link hub 4 to have a wide range of movement relative to the base end link hub 5.

[0024] The vertical angle by which the central axis QB of the tip link hub 4 is inclined relative to the central axis QA of the base link hub 5 is called the bend angle. The rotation angle of the tip link hub 4 relative to the base link hub 5 can be set within the range of 0° to 360°. The rotation angle is the horizontal angle by which the central axis QB is inclined relative to the central axis QA. In this mechanism, there is no restriction on the rotation angle independent of the bend angle. The tip link hub 4 can be rotated relative to the base link hub 5 with the central axis QB inclined relative to the central axis QA, allowing for multiple rotations. Furthermore, the rotation direction of the rotation angle can be unidirectional or bidirectional. The origin position is the position in which the center point of the base spherical link, the link center point, and the center point of the tip spherical link are aligned on a straight line. In the origin position of the parallel link mechanism 2, the bend angle and the rotation angle are both 0°.

[0025] The position of the distal link hub 4 relative to the proximal link hub 5 is changed around the intersection of the central axes QA and QB as the center of rotation. Even if the position of the distal link hub 4 relative to the proximal link hub 5 changes, the distance between the proximal and distal spherical link centers PA and PB does not change. The three link mechanisms 6 shown in FIG. 3 are arranged at equal circumferential intervals of 120 degrees, but they do not necessarily have to be arranged at equal circumferential intervals.

[0026] <Hub components, etc.> As shown in FIGS. 4 and 5, the base-side link hub 5 and the tip-side link hub 4 in FIG. 1 each include a plurality of (three in this example) hub components 11 and a connecting plate HP, which is a hub connecting member that connects these hub components 11. The three hub components 11 have the same shape. The base-side hub component 11, which is a hub component in the base-side link hub 5, and the tip-side hub component 11, which is a hub component in the tip-side link hub 4, have the same shape.

[0027] As shown in FIG. 4, each hub component 11 has a revolute pair 13 and a connecting portion 14. The revolute pair 13 rotatably connects the base end link member 7 or the tip end link member 9 shown in FIG. 2. The revolute pair 13 shown in FIG. 4 includes a shaft member 13a (FIG. 4) that can rotate around the first rotation shaft 10a or the second rotation shaft 10b of the parallel link mechanism 2 assembled as shown in FIG. 2. As shown in FIG. 4, a bearing and a spacer are provided as rotational resistance reduction members 16 on the revolute pair 13 of each hub component 11. The bearing reduces sliding resistance between the hub component 11 and the shaft member 13a. The spacer reduces sliding resistance between the hub component 11 and the bearing and the base end or tip end link member 7, 9 (FIG. 2). However, the bearing may be omitted depending on the operating conditions, application, etc.

[0028] Two or more connecting portions 14 are required to prevent deformation of the link hub. In this example, the connecting portions 14 are provided at both longitudinal ends of the hub component 11, and adjacent hub components are fixed together with connecting plates HP (see FIG. 5). The link hub is assembled by fixing the hub component 11 to the connecting plates HP with multiple (six in this example) bolts Bt or pins. In this case, it is essential that the first rotation axes 10a (or second rotation axes 10b) at the rotation pairs 13 of each link hub intersect at a single point by the connecting plates HP, as shown in FIG. 6. This intersection is the spherical link center PA on the base end side or the spherical link center PB on the tip end side.

[0029] The connecting plate HP may be a base on the base end side or an end effector mounting member on the tip end side. The connecting plate HP may be provided with holes for fixing an end effector or the like. The connecting plate HP of this embodiment is provided with connecting holes for passing bolts Bt and holes 19 for passing cables or the like. In addition, the connecting plate HP is formed in a C-shape in plan view with one opening in the circumferential direction, making it easy to pass cables or the like through the opening SL.

[0030] <Unit> The parallel link mechanism 2 in FIG. 1 is composed of three structurally equivalent units Ut. As shown in FIG. 3, the three units Ut are arranged at equal intervals in the circumferential direction, but they do not have to be spaced at equal intervals. The number of units needs to be two or more. In other words, the number of units Ut is determined according to the number of sets of the link mechanism 6. As shown in FIG. 7, one unit Ut includes a base-end hub component member 11, a base-end link member 7, a central link member 8, a tip-end link member 9, and a tip-end hub component member 11, and adjacent components are rotatably connected to each other. In each unit, each of the rotation axes 10a to 10d can rotate freely.

[0031] <Regarding the positioning part and positioning member> As shown in Figure 8, the base end link member 7 and the tip end link member 9 have substantially cylindrical protrusions 21, 21 as positioning portions. These protrusions 21, 21 protrude outward from the link of the end link member and are provided parallel to the first and second rotation shafts 10a, 10b. Each protrusion 21 may be detachably provided on the end link member. As shown in Figure 9, each protrusion 21 preferably has a structure that prevents a positioning member 17 (described later) attached to the protrusion 21 from falling off.

[0032] As shown in Figure 8, positioning members 17 are detachably attached to the protrusions 21, 21. When attached to the protrusions 21, 21, the positioning members 17 restrict the posture of the link mechanism 6 of one unit Ut. The positioning member 17 is in the shape of a rectangular flat plate and is provided with slits 17c through which the base ends 21a (Figure 9) of the protrusions 21, 21 are guided. The slits 17c open at one longitudinal end of the positioning member 17 and extend to near the other longitudinal end. At least two positioning members 17 are sufficient when assembling the parallel link mechanism.

[0033] The tip end 21b of each projection 21 is formed with a diameter larger than the base end 21a (FIG. 9) and the groove width of the slit 17c, thereby preventing the positioning member 17 from undesirably falling off the projection 17. The other longitudinal end of the positioning member 17 is provided with a gripping portion 17b for gripping the positioning member 17 with fingers or the like. The slit 17c and gripping portion 17b can be easily formed, for example, by press working or the like. In this embodiment, when the protrusions 21, 21 are fitted into the slits 17c of the positioning member 17 to attach it, the base end link member 7 and the tip end link member 9 are constrained relative to the central link member 8. However, the first rotating shaft 10a and the second rotating shaft 10b are able to rotate freely.

[0034] A necessary condition for constraining the posture of the link mechanism 6 of one unit Ut is that the pair of first and second rotating shafts 10a, 10b in the unit Ut be constrained on the same plane Pl. In this embodiment, the first and second rotating shafts 10a, 10b are both perpendicular to the plane of the positioning member 17. Therefore, the first and second rotating shafts 10a, 10b are parallel and constrained on the same plane Pl. The protrusions 21, 21 provided on the end link members are configured to constrain the pair of first and second rotating shafts 10a, 10b in the unit Ut on the same plane Pl.

[0035] If a positioning member 17 is attached to the protrusions 21, 21 and the pair of first rotating shaft 10a and second rotating shaft 10b in unit Ut are constrained to the same plane Pl, the link mechanism 6 of unit Ut can be positioned even if it is tilted relative to the original posture of the parallel link mechanism. Of course, the units Ut may be restrained in the origin position. In this case, the positions of all the units Ut are the same, and the positioning members 17 can be made the same shape. If the positioning members Ut have different shapes, positions other than the origin position can also be accommodated.

[0036] In one unit Ut, the pair of first and second rotating shafts 10a, 10b need not be twisted. The protrusions 21, 21 at the tip and base ends do not need to be in a mirror image relationship. The positioning member 17 is not limited to being flat. The positioning member 17 is detached from the protrusions 21, 21 after the parallel link mechanism is assembled. The distance between the center point of the spherical link and the center point of the parallel link mechanism can be changed depending on the design. It is also possible to move only the center point of the spherical link farther away from the link hub without changing the position of the link hub.

[0037] <Attitude control actuator> As shown in FIG. 1 , the link actuation device 1 includes attitude control actuators 3 in all three link mechanisms 6. The attitude control actuators 3 are electrically connected to and controllable by the control device Cu. The control device Cu controls the attitude control actuators 3 to control the bending angle and the rotation angle of the link actuation device 1. Each attitude control actuator 3 is, for example, a rotary actuator, and is installed coaxially with the first rotation axis 10a on the outer surface of the base end link hub 5. If at least two of the three link mechanisms 6 are provided with attitude control actuators 3, the attitude of the tip end link hub 4 relative to the base end link hub 5 can be determined.

[0038] The link actuation device 1 rotates and drives each of the attitude control actuators 3, thereby actuating the parallel link mechanism 2. More specifically, when the attitude control actuators 3 are rotated, the rotation is transmitted to the first rotation shaft 10a. This allows the attitude of the tip-end link hub 4 relative to the base-end link hub 5 to be changed as desired. Similar attitude control actuators 3 can be attached to parallel link mechanisms according to other embodiments described below. An end effector (not shown) is attached to the tip-end link hub 4. Examples of the end effector include a hand including a gripper, a cleaning nozzle, a dispenser, a welding torch, and image processing equipment.

[0039] <Assembly method> The method of assembling the parallel link mechanism 2 comprises, in order, a unit assembly process, a link constraint process, and a fixing process. In the unit assembly process, as shown in Figure 7, a unit Ut is assembled, which includes a base-end hub component 11, a base-end link member 7, a central link member 8, a tip-end link member 9, and a tip-end hub component 11. The following assembly order within the unit Ut can be changed as desired. It is advisable to attach the attitude control actuator 3 when assembling the unit Ut. This makes it easier to insert tools into the attachment portion, and installation is easier than after the parallel links have been assembled.

[0040] The base-end hub component 11 and one end of the base-end link member 7 are rotatably connected to each other. The other end of the base end link member 7 and one end of the central link member 8 are rotatably connected. The other end of the central link member 8 and one end of the tip side link member 9 are rotatably connected. The other end of the tip-side link member 9 and the tip-side hub component member 11 are rotatably connected. The attitude control actuator 3 is connected to the base end link member 7.

[0041] In the link restraint process, the posture of the link mechanism 6 of one unit Ut is restrained using a positioning member 17. That is, as shown in Figure 8, the positioning member 17 is attached to the protrusion 21 of the base-end link member 7 and the protrusion 21 of the tip-end link member 9. In the fixing process, as shown in Figure 1, multiple hub components 11 are fixed by a connecting plate HP. That is, the unit Ut is connected to the connecting plate HP to form the base-end link hub 5 and the tip-end link hub 4, and the parallel link mechanism 2 is assembled. After this assembly, the positioning member 17 is removed and the mechanism is ready for use.

[0042] <Action and effect> The parallel link mechanism 2 described above can be configured as a mechanism in which the base-end link hub 5, the tip-end link hub 4, and two or more sets of link mechanisms 6 allow the tip-end link hub 4 to rotate with two degrees of freedom and freely change its position relative to the base-end link hub 5. Protrusions 21 are provided as positioning portions on the base-end and tip-end hub components 11, 11 or on the end link members, which are the base-end and tip-end link members 7, 9. The protrusions 21, 21 are configured to constrain the pair of first and second rotating shafts 10a and 10b (FIG. 2) in the unit Ut to be on the same plane.

[0043] By using the unit Ut, it becomes easier to attach and assemble the parts inside the parallel link. Maintenance can be improved by replacing the units. By using the protrusions 21, 21 to restrict the position of each unit, the parallel link mechanism 2 can be assembled easily without undesired movement. Furthermore, the unit Ut can be easily stored and transported. According to the above assembly method, in particular, by using the positioning member 17 to restrain the posture of the link mechanism 6 of one unit Ut, the link mechanism 6 does not move, and the units can be easily connected to each other.

[0044] The link actuation device 1 is equipped with the attitude control actuator 3, so it can determine the attitude of the tip-side link hub 4 relative to the base-side link hub 5. Combining the attitude control actuator 3 with the parallel link mechanism 2 enables precise, wide-range, high-speed operation, resulting in a lightweight and compact link actuation device 1.

[0045] <Other embodiments> In the following description, parts corresponding to matters previously described in each embodiment are given the same reference numerals, and duplicated description will be omitted. When only a part of the configuration is described, the other parts of the configuration are the same as the previously described embodiment unless otherwise specified. The same functions and effects are achieved from the same configuration. It is possible to combine not only the parts specifically described in each embodiment, but also parts of the embodiments together, provided that there is no particular problem with the combination.

[0046] [Second embodiment: Figs. 10 to 17] As shown in Figures 10 and 12, a parallel link mechanism 2A according to the second embodiment is provided with positioning portions 15 on the base-end and tip-end hub components 11A, 11B. The positioning portions 15 are through-holes that penetrate in the vertical direction, and a positioning member 17A can be inserted into each of the through-holes in the base-end and tip-end hub components 11, 11. As shown in Figure 11, the positioning member 17A has a rod-shaped insertion portion 17a of a predetermined length with a circular cross-section, and a grip portion 17b that is provided at one longitudinal end of the insertion portion 17a and can be gripped with fingers or the like. Rods with a circular cross-section are advantageous in that they are easy to obtain and have little anisotropy in strength.

[0047] 10, when the positioning member 17A is inserted into the positioning portions 15 of the base-end and tip-end hub components 11A, 11B, the posture of the link mechanism 6 is constrained. When the posture of the link mechanism 6 is constrained, the first rotating shaft 10a and the second rotating shaft 10b cannot rotate either.

[0048] <Hub components> As shown in Figures 13 and 14, the base-end and tip-end hub components 11A, 11B each have two connecting portions 14, 14, one revolute pair 13, and a through-hole as a positioning portion 15. Because the positioning portion 15 fits within the link hub, it is easy to design the link hub so that it does not interfere. The positioning portion 15 only needs to be able to hold the positioning member 17A (Figure 10) during assembly. Therefore, the positioning portion 15 may be a notch or protrusion other than a through-hole, or it may not even be a through-hole. Additionally, the positioning portion 15 is easier to process if it is perpendicular to the top and bottom surfaces of the hub components 11A, 11B.

[0049] In the second embodiment, the link hubs on the proximal and distal ends have different shapes. As shown in Figure 15, the base-side link hub 5 uses a plate-shaped member as the hub connecting member HPa that connects multiple hub components 11A. To secure the hub components 11A to the plate-shaped member, a connecting portion 14 is provided on the underside of the hub components 11A. The center point of the spherical link on the base-side is slightly shifted upward from the center of the base-side link hub 5 in the vertical direction. This is because the attitude control actuator 3 is positioned above the top surface of the hub connecting member HPa, as shown in Figure 10.

[0050] 15, in order to evenly arrange the multiple hub components 11A, the central axis of the base-end link hub 5 and the spherical link center point PA coincide. However, it is possible in design to deviate the central axis of the base-end link hub 5 from the spherical link center point PA. 10, the output shaft of the attitude control actuator 3 is arranged parallel to the plane of the hub connecting member HPa, so each of the first rotation axes is on a plane parallel to the hub connecting member HPa. Note that it is possible to design each of the first rotation axes 10a and each of the third rotation axes 10c to have a different angle.

[0051] As shown in Figure 16, the tip-side link hub 4 uses a triangular prism member as the hub connecting member HPb that connects multiple hub components 11B. To secure the hub components 11B to each wall surface of the triangular prism, connecting portions 14, 14 are provided on the side surfaces of the hub components 11B. Using a triangular prism member as the hub connecting member HPb improves strength compared to a plate-shaped hub connecting member.

[0052] As shown in FIG. 17, in the second embodiment, when the unit Ut is positioned in the origin posture, the base-side hub component 11A and the tip-side hub component 11B of the unit Ut are parallel. By inserting a positioning member 17A into the positioning portions 15, 15 of the unit Ut, the first rotating shaft 10a of the base-side hub component 11A and the second rotating shaft 10b of the tip-side hub component 11B of the unit Ut are constrained so that they cannot rotate. In this case, the posture of one unit Ut is further constrained, making it even easier to align the units with each other. This can further improve the ease of assembly of the parallel link mechanism.

[0053] As shown in Figure 10, the end effector Ea is attached to the distal link hub 4. The attitude control actuator 3 is fixed to the hub connecting member HPa of the proximal link hub 5. The smaller the distal link hub 4 is and the less it protrudes, the more interference can be avoided and the smaller the moment of inertia is, which is preferable. The proximal link hub 5 should be able to secure the attitude control actuator 3 and to be fixed to the base. The assembly method is the same as that of the first embodiment, and therefore will not be described. The end effector Ea is assembled in a separate process from the assembly of the parallel link mechanism 2A. For example, after assembling the parallel link mechanism 2A, the end effector Ea is attached before use.

[0054] [Third embodiment: Figs. 18 to 25] As shown in Figure 18, a parallel link mechanism 2B according to the third embodiment is provided with a positioning member 15A at a rotational pair that connects a hub component 11C and an end link member. More precisely, as shown in Figure 21, the link mechanism 6 is positioned by a plate-shaped positioning member 17B coming into contact with the spacer, which is the rotational resistance reduction member 16 of the rotational pair 13, the hub component 11C, and the end link member shown in Figure 19. As shown in Figure 20, the base-end and tip-end link hubs 5, 4 each include multiple (three in this example) hub components 11C and hub connecting members 12, such as bolts, that connect these hub components 11C in an annular shape.

[0055] As shown in Figure 21, each hub component 11C has one longitudinal end at a predetermined angle relative to the other longitudinal end, with the center point being near the midpoint. Each hub component 11C has connecting portions 14 at both longitudinal ends, and the rotational pairs 13 with the end link members also serve as positioning portions 15. The connecting portions 14 at both ends are staggered and can be overlapped with the connecting portions 14 of other hub component members 11C. The connecting portions 14 at both ends are provided with through holes 14h that can be fastened with the bolts. As shown in Figure 22, when three connecting parts 14 are connected in the circumferential direction, the position and angle of the hub component 11C are fixed, so even if the connecting parts 14 are rotatable, the base end and tip end link hubs 5, 4 do not deform.

[0056] 23 and 25, the positioning member 17B is a plate-like member having notches 17Ba, 17Ba for aligning the revolute pair 13 of the tip-side link member 9 and the revolute pair 13 of the base-side link member 7. As shown in Figure 24, when the revolute pairs 13, 13 are fixed perpendicular to the plane formed by the positioning member 17B, the postures of the tip-side link member 9, central link member 8, and base-side link member 7 in the unit Ut are uniquely determined.

[0057] In the unit Ut, the notches 17Ba, 17Ba contact the spacers of the revolute pairs 13, 13, restricting the distance between the revolute pairs 13, 13. In addition, the plate surface of the positioning member 17B contacts the side surfaces of the hub component 11C, end link member, and spacer, restricting the angle between the revolute pairs 13, 13. The hub component 11C is rotatable at the revolute pairs 13. Because the revolute pairs 13 of each hub component 11 also serve as the positioning portions 15, little processing is required to form the positioning portions, which can be achieved at low cost. The assembly method is the same as that of the first embodiment, and therefore will not be described.

[0058] Although the embodiments of the present invention have been described above, the disclosed embodiments are illustrative in all respects and are not restrictive. The scope of the present invention is defined by the claims rather than the above description, and it is intended to include all modifications within the scope and meaning equivalent to the claims. [Explanation of symbols]

[0059] 1...link actuator, 2, 2A, 2B...parallel link mechanism, 2a, 2b...spherical link mechanism, 3...attitude control actuator, 4...tip side link hub, 5...base side link hub, 6...link mechanism, 7...base side link member, 8...central link member, 9...tip side link member, 10a...first rotating shaft, 10b...second rotating shaft, 11, 11A, 11B, 11C...hub component member, HP...connecting plate (hub connecting member), 13...rotation pair portion, 14...connecting portion, 17, 17A, 17B...positioning member, Ut...unit, 21...protrusion (positioning portion)

Claims

1. a distal link hub is connected to a proximal link hub via two or more sets of link mechanisms so as to be able to change its position, and each of the link mechanisms uses a spherical link mechanism having a proximal link member, a central link member, and a distal link member; a parallel link mechanism in which one end of the base-side link member is coupled to the base-side link hub so as to be rotatable about a first rotation axis, and one end of the tip-side link member is coupled to the tip-side link hub so as to be rotatable about a second rotation axis, the base end link hub and the tip end link hub each include a plurality of hub components and a hub connecting member that connects these hub components; Each of the hub components has a revolute pair that rotatably connects the base-end link member or the tip-end link member, and a connecting portion that fixes adjacent hub components to each other with the hub connecting member, Regarding a unit including the base end side hub component, the base end side link member, the central link member, the tip end side link member and the tip end side hub component, and in which adjacent members are connected to each other, A parallel link mechanism having positioning portions provided on the base end side and tip end side hub constituent members or the end link members which are the base end side and tip end side link members.

2. 2. The parallel link mechanism according to claim 1, wherein the positioning portion can constrain the first rotation shaft of the hub component member on the base end side and the second rotation shaft of the hub component member on the tip end side in the unit so that they cannot rotate.

3. A method for assembling a parallel link mechanism using a spherical link mechanism in which a tip-side link hub is connected to a base-side link hub via two or more link mechanisms so that its posture can be changed, and each of the link mechanisms has a base-side link member, a central link member, and a tip-side link member in that order, the base end link hub and the tip end link hub each include a plurality of hub components and a hub connecting member that connects these hub components; a unit assembling process for assembling a unit including the base-end hub component, the base-end link member, the central link member, the tip-end link member, and the tip-end hub component; a link restraining step of restraining the posture of the link mechanism of one of the units using a positioning member; a fixing step of fixing the plurality of hub constituent members with the hub connecting member.

4. 3. A link actuation device comprising: a parallel link mechanism according to claim 1, wherein the two or more link mechanisms are provided with a posture control actuator for arbitrarily controlling the posture of the distal end link hub.

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