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: In the parallel link mechanism 2, a distal end side link hub 4 is connected to a proximal end side link hub 5 via two or more link mechanisms 6 in a posture changeable manner, and each link mechanism 6 has a proximal end side link member 7, a central link member 8, and a distal end side link member 9. Each of the proximal-side link hub 5 and the distal-side link hub 4 includes a plurality of hub constituent members 11 and a hub coupling member 12 that couples the hub constituent members 11 in an annular shape. Each hub constituting member 11 has a revolute pair part 13 for rotatably connecting the base end side link member 7 or the tip side link member 9, a connecting part 14 for fixing the hub constituting members to each other by the hub connecting member 12, and a positioning part 15 for rotatably positioning the hub constituting members to each other.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 for the same. [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 the parts cannot be connected. The parallel links and hubs are positioned at different angles to each other, and can freely change position during assembly. 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] The parallel link mechanism of the present invention is a parallel 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 the posture of the tip side link hub 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, the base-side link hub and the tip-side link hub each include a plurality of hub constituent members and a hub connecting member that connects these hub constituent members in an annular shape; Each of the hub components has a rotational pair that rotatably connects the base-end link member or the tip-end link member, a connecting portion that fixes the hub components together with the hub connecting member, and a positioning portion that positions the hub components together.

[0007] This configuration allows the base-end link hub, the tip-end link hub, and two or more link mechanisms to form a mechanism that allows the tip-end link hub to rotate with two degrees of freedom and freely change its position relative to the base-end link hub. The base-end link hub and the tip-end link hub each include multiple hub components and a hub connecting member that connects these hub components in an annular shape. The positioning portions provided on the hub components allow the hub components to be rotatably positioned relative to each other, aligning the spherical link center points and allowing the parallel link mechanism to be assembled. This improves the ease of assembly of the parallel link mechanism compared to conventional structures.

[0008] The positioning portion of the base-end hub component and the positioning portion of the tip-end hub component may be on the same straight line. In this case, a unit including the base-end hub component, base-end link member, central link member, tip-end link member, and tip-end hub component is formed, and this unit is rotatable about the positioning portion while connected to each other. This further improves the ease of assembly of the parallel link mechanism.

[0009] The base-side link hub and the tip-side link hub may each have three of the hub components. In this case, when adjacent hub components are connected to each other with a connecting portion, the positions and angles of the hub components are fixed. Therefore, even if the connecting portion is rotatable, the link hub does not deform. In this way, the shapes of the base-side link hub and the tip-side link hub are uniquely determined during the assembly stage, so there is little error during assembly.

[0010] The connecting portion of the hub component may also serve as the positioning portion. In this case, the structure of the hub component can be simplified and manufacturing costs can be reduced compared to a hub component in which the connecting portion and the positioning portion are provided separately.

[0011] A method for assembling a parallel link mechanism according to a first aspect 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 the posture of the tip-side link hub 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, the base-side link hub and the tip-side link hub each include a plurality of hub constituent members and a hub connecting member that connects these hub constituent members in an annular shape; 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 temporary fixing process in which the process of temporarily fixing the base end side hub components of the two units together and the tip end side hub components of the two units together on the same axis is repeated to temporarily fix the required number of hub components together; and a fixing step of fixing the plurality of hub constituent members in an annular shape by the hub connecting member.

[0012] According to this assembly method, in the unit assembly process, a unit is assembled that includes a base-end hub component, a base-end link member, a central link member, a tip-end link member, and a tip-end hub component. In the temporary fastening process, the base-end hub components of the two units are temporarily fastened together coaxially, and the tip-end hub components are temporarily fastened together, repeating this process until the required number of hub components are temporarily fastened. Then, in the fixing process, the multiple hub components are fixed in a circular ring shape using hub connecting members. By assembling the units in this way first and then using the hub components as link hubs, the entire parallel link mechanism can be easily assembled.

[0013] A method for assembling a parallel link mechanism according to a second aspect 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 a base-side link member, a central link member, and a tip-side link member, the base-side link hub and the tip-side link hub each include a plurality of hub constituent members and a hub connecting member that connects these hub constituent members in an annular shape; 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 first fixing step of fixing the base end side hub component member and the tip end side hub component member of one of the units to the hub connecting member, respectively; a connecting step of rotatably connecting the hub components of the two units using a positioning member; and a second fixing step of fixing the plurality of hub constituent members in a circular shape by the hub connecting member.

[0014] According to this assembly method, in the unit assembly process, a unit including a base-end hub component, a base-end link component, a central link component, a tip-end link component, and a tip-end hub component is assembled. In the first fixing process, the base-end hub component and the tip-end hub component of one unit are fixed to the hub connecting member, respectively. In the connecting process, the hub components of two units are rotatably connected using a positioning member. Then, in the second fixing process, the multiple hub components are fixed in an annular shape by the hub connecting member. Each unit is fixed individually by the hub connecting member, and as long as two units remain to maintain the parallel link mechanism, the other units can be removed. This improves maintainability compared to conventional structures. Other effects are achieved similar to those of the parallel link mechanism assembly method of the first invention.

[0015] 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]

[0016] In the parallel link mechanism of the present invention, 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 in an annular shape, and the hub components are positioned rotatably relative to one another by the positioning portions provided on the hub components, thereby improving the ease of assembly of the parallel link mechanism. [Brief explanation of the drawings]

[0017] [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. 2 is a front view of the parallel link mechanism. [Figure 3] FIG. 2 is a plan view of a link actuator including the parallel link mechanism. [Figure 4] FIG. 2 is a plan view of the parallel link mechanism when assembled. [Figure 5] FIG. 2 is a perspective view of a hub component member of the parallel link mechanism. [Figure 6] FIG. 2 is a perspective view of a link hub of the parallel link mechanism. [Figure 7] FIG. [Figure 8] FIG. 4 is a plan view of the link hub during assembly. [Figure 9] FIG. 2 is a perspective view of one unit of the parallel link mechanism. [Figure 10] FIG. [Figure 11A] FIG. 2 is a perspective view of the parallel link mechanism during assembly. [Figure 11B] FIG. 2 is a plan view of the parallel link mechanism. [Figure 12] FIG. 10 is a perspective view of a parallel link mechanism according to a second embodiment of the present invention. [Figure 13] FIG. 2 is a front view of the parallel link mechanism. [Figure 14] FIG. 2 is a plan view of the parallel link mechanism. [Figure 15A] FIG. 2 is a perspective view of a link hub of the parallel link mechanism. [Figure 15B] FIG. [Figure 16] FIG. 2 is a perspective view of a hub component of the link hub. [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 link hub of the parallel link mechanism. [Figure 22] FIG. 2 is a perspective view of a unit of the parallel link mechanism. [Figure 23A] FIG. 2 is a perspective view of four units of the parallel link mechanism during assembly. [Figure 23B] FIG. 2 is a plan view of four units of the parallel link mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0018] [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 11B.

[0019] <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).

[0020] <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.

[0021] Each link mechanism 6 includes, in order, a base-side link member 7, a central link member 8, and a distal-side link member 9, forming a four-bar link mechanism consisting of 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 FIGS. 3 and 4, 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."

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] The vertical angle at which the central axis QB of the distal link hub 4 is tilted relative to the central axis QA of the proximal link hub 5 is called the bend angle. The rotation angle of the distal link hub 4 relative to the proximal link hub 5 can be set within the range of 0° to 360°. The rotation angle is the horizontal angle at which the central axis QB is tilted relative to the central axis QA. With this mechanism, there is no restriction on the rotation angle independent of the bend angle. The distal link hub 4 can be rotated relative to the proximal link hub 5 with the central axis QB tilted relative to the central axis QA, allowing for multiple rotations. Furthermore, the rotation direction of the rotation angle can be in one direction or another.

[0029] 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.

[0030] <Hub components, etc.> As shown in FIGS. 6 and 7, the base-side link hub 5 and the tip-side link hub 4 in FIG. 1 each include a plurality of hub components 11 (three in this example) and a hub connecting member 12 that connects these hub components 11 in an annular shape. The three hub components 11 are identical in 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, are identical in shape. Bolts or the like are used as the hub connecting member 12. As shown in FIG. 5, each hub component 11 has a predetermined inclination angle between the extension direction of one longitudinal end and the extension direction of the other longitudinal end, with the center being near the midpoint in the longitudinal direction. Each hub component 11 has a revolute pair 13, a connecting portion 14, and a positioning portion 15.

[0031] The revolute pair 13 rotatably connects the base end link member 7 or the tip end link member 9 in Figure 2. As shown in Figure 5, the revolute pair 13 of each hub component 11 is provided with a bearing and a spacer as a rotational resistance reduction member 16. The bearing reduces the sliding resistance between the hub component 11 and the shaft member. The spacer reduces the sliding resistance between the hub component 11 and the bearing and the base end or tip end link member 7, 9 (Figure 2). However, the bearing may be omitted depending on the conditions of use, application, etc.

[0032] The connecting portions 14 are provided at both longitudinal ends of the hub component 11, and adjacent hub components are fixed to each other with a hub connecting member 12 (Figure 1). The connecting portions 14 at both ends are staggered and can be overlapped with the connecting portions 14 of other hub components 11. The connecting portions 14 at both ends are provided with through holes 14h that can be fixed with the bolts. Positioning portions 15 are provided at both longitudinal ends of the hub component 11, and rotatably position adjacent hub components to each other. In this embodiment, the connecting portions 14 also serve as the positioning portions 15. When three connecting portions 14 are connected in the circumferential direction as shown in Figure 6, the position and angle of the hub component 11 are fixed, so that the base-side and tip-side link hubs 5, 4 do not deform, even if the connecting portions 14 are rotatable.

[0033] 2, when the assembled parallel link mechanism 2 is in the origin position, the positioning portion 15 at one end of the base-end hub component 11 and the positioning portion 15 at one end of the tip-end hub component 11 are aligned on the same straight line. At the same time, the positioning portion 15 at the other end of the base-end hub component 11 and the positioning portion 15 at the other end of the tip-end hub component 11 are also aligned on the same straight line. The origin position in this example is a position where the bend angle is 0 degrees and the rotation angle is 0 degrees.

[0034] When the positioning portions 15 of the base-end hub component 11 and the tip-end hub component 11 are aligned in the same straight line, the two connected units (described later) can rotate like a hinge around the positioning portion 15 as an axis, as shown in Figure 8. The parallel link mechanism 2 in FIG. 1 is composed of three structurally equivalent units A, B, and C. As shown in FIG. 9, each unit A (B, C) 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. As shown in FIG. 10, in each unit A, B, or C, the base-end hub component 11 and the tip-end hub component 11 have positioning portions 15 / connecting portions 14 at both ends that are mirror images of each other with respect to the mid-plane IP. The mid-plane IP is the plane where a moving spherical surface centered on the base-end spherical link center PA (FIG. 2) intersects with a moving spherical surface centered on the tip-end spherical link center PB (FIG. 2).

[0035] <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.

[0036] 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.

[0037] <Assembly method> The method for assembling the parallel link mechanism 2 includes, in order, a unit assembly process, a temporary fastening process, and a fixing process. In the unit assembly process, as shown in Figure 9, unit A (B, C) 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. This is repeated for the number of units to assemble three units A, B, and C. The following assembly order within the unit can be changed as desired. It is a good idea to attach the attitude control actuator 3 when assembling the unit. This makes it easier to insert tools into the attachment section, and installation is easier than after the parallel links have been assembled.

[0038] 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 (FIG. 1) is connected to the base end link member 7.

[0039] In the temporary fastening process, as shown in Figure 4, the base-end hub components 11 of the two units A and B and the tip-end hub components 11 of the two units A and B are temporarily fastened together coaxially using positioning portions 15. This process is repeated as shown in Figures 11A and 11B to temporarily fasten the required number of hub components 11. Specifically, as shown in Figure 8, the positioning portions 15 / connecting portions 14 of the base-end and tip-end hub components 11, 11 of units A and B, and B and C are rotatably connected.

[0040] In this embodiment, so-called screw fastening is assumed, so the two units are loosely fastened temporarily to enable rotation. When connecting units together, you can connect them from either the base end or the tip end. However, it is essential that both the base end and tip end of the unit are connected, as the unit will deform due to gravity if only one end is connected. · Units AB and BC can rotate at the connecting part 14, forming a state similar to two connected hinges. In this case, each unit A (B, C) has its own spherical link center point due to the end link members. However, when units AB and BC are rotatably connected at connecting portion 14, the spherical link centers of units A (B, C) do not coincide, so the spherical links do not deform and do not deform undesirably.

[0041] In the fixing process, the multiple hub components 11 are fixed in a circular shape by the hub connecting member. Specifically, the units AB and BC are rotated at the connecting portions 14, and the positioning portions 15 / connecting portions 14 of the hub components 11, 11 on the base end side and tip end side of units C and A are connected. There are two points where the circular orbit O1 at the center of the connecting part of unit AB intersects with the circular orbit O2 at the center of the connecting part of unit BC. From the link arrangement at the time of design, it is possible to determine which of these two points should be connected to the last connecting part 14.

[0042] When there are three hub components 11, the triangle formed by the connecting portions 14 can only be changed by design, and the spherical links must be designed so that their center points intersect at one point.

[0043] 3, when the third point of the connecting portion 14 is connected, the connecting portion 14 becomes unable to rotate. In this case, the angle of the rotation pair 13 is determined, and the center points of the spherical links coincide. Thereafter, the bolts of each connecting portion 14 are tightened and fixed, thereby completing the assembly of the parallel link mechanism 2. By assembling the units in advance in this way and using the hub component member 11 as a link hub, the entire parallel link mechanism can be easily assembled.

[0044] <Action and effect> 1 described above, the base-end link hub 5, the tip-end link hub 4, and two or more sets of link mechanisms 6 can form a mechanism in which the tip-end link hub 4 can rotate with two degrees of freedom and freely change its position relative to the base-end link hub 5. The base-end link hub 5 and the tip-end link hub 4 each include a plurality of hub components 11 and a hub connecting member 12 that connects these hub components 11 in an annular shape. The positioning portions 15 provided on the hub components 11 can be used to position the hub components 11 rotatably relative to one another, aligning the spherical link center points and assembling the parallel link mechanism 2. This improves the ease of assembly of the parallel link mechanism 2 compared to conventional structures.

[0045] The positioning portion 15 of the base-end hub component 11 and the positioning portion 15 of the tip-end hub component 11 are on the same straight line. In this case, units A, B, and C are formed, each including the base-end hub component 11, base-end link member 7, central link member 8, tip-end link member 9, and tip-end hub component 11, and these units are connected to each other and can rotate around positioning portion 15. This makes it possible to more reliably improve the ease of assembly of the parallel link mechanism 2.

[0046] As shown in Figure 5, the connecting portion 14 of the hub component 11 also serves as the positioning portion 15. In this case, the structure of the hub component 11 can be simplified and manufacturing costs can be reduced compared to hub components in which the connecting portion and positioning portion are provided separately. Because the hub component 11 on the base end side and the hub component 11 on the tip end side have the same shape, the versatility of the parts is increased, and manufacturing costs can be reduced. As shown in Figure 1, by configuring the parallel link mechanism 2 with multiple units A, B, and C, it becomes easier to attach and assemble the parts inside the parallel link. Maintenance can also be improved by replacing units.

[0047] 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.

[0048] <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 those in the previously described embodiment unless otherwise specified. The same configuration produces the same effects. It is possible to combine not only the parts specifically described in each embodiment, but also partially combine embodiments as long as there is no particular problem with the combination.

[0049] [Second embodiment: Figs. 12 to 17] The parallel link mechanism 2A in FIG. 12 is also made up of three structurally equivalent units A, B, and C. The parallel link mechanism 2A has connecting plates (hub connecting members) HP, which connect multiple hub components 11A, on the base end and tip end sides as shown in FIG. 13. By connecting the units A, B, and C with the connecting plates HP as shown in FIG. 14, even if one unit is removed from the three units A, B, and C, the other units do not move and the parallel link mechanism 2A can be maintained. This makes it possible to replace each unit individually.

[0050] As shown in FIG. 12, the parallel link mechanism 2A uses a positioning member 17 during assembly. The positioning member 17 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 is held by fingers or the like. During assembly, the insertion portion 17a of the positioning member 17 can be inserted into the positioning portion 15 of the hub component 11A on the base end side and the positioning portion 15 of the hub component 11A on the tip end side. It is an essential condition that the units A, B, and C shown in FIG. 17 be positioned by rotation, and therefore the insertion portion 17a of the positioning member 17 must have a circular cross section.

[0051] As shown in Figures 15A and 15B, the base-end and tip-end link hubs 5, 4 are configured by immovably fixing the connecting portion 14 of the hub component 11A to a connecting plate HP. The connecting plate HP, which is a hub connecting member, has a connecting portion 18 and a hole 19 for wiring. The connecting plate HP may also have an attachment portion for attaching the attitude control actuator 3 (see Figure 1) or an end effector. The connecting plate HP does not have a positioning portion, and only has the function of fixing the hub component 11A positioned by the positioning member 17 in Figure 13.

[0052] As shown in Figure 16, positioning portions 15, 15 are provided at both longitudinal ends of the hub component 11A. The positioning portion 15 at one end, which is the left side of Figure 16, is formed in a convex shape that protrudes substantially along the longitudinal direction, and the positioning portion 15 at the other end is formed in a concave shape. Each of the positioning portions 15, 15 has a hole 15a through which the insertion portion 17a of the positioning member 17 in Figure 17 passes. The hub component 11A in Figure 16 is provided with two or more (two in this example) connecting portions 14.

[0053] <Assembly method> The assembly method for the parallel link mechanism 2A in Figure 12 includes a unit assembly process, a first fixing process, a connecting process, and a second fixing process. In the unit assembly process, as shown in Figure 17, a unit A (B, C) is assembled, which includes a base-end hub component 11A, a base-end link member 7, a central link member 8, a tip-end link member 9, and a tip-end hub component 11A. This process is repeated three times to assemble the three units A, B, and C. The assembly order within the unit can be changed as desired.

[0054] In the first fixing process, as shown in Figure 15A, a connecting plate HP is fixed to the connecting portion 14 of the hub component 11A on the base end side of one unit and the connecting portion 14 of the hub component 11A on the tip end side. This first fixing process may also be performed after the three units A, B, and C have been positioned using multiple positioning members 17, as shown in Figure 12. By positioning and connecting units A, B, and C one unit at a time, this process can be performed using only one positioning member 17.

[0055] During the connecting process, the insertion portions 17a of the positioning member 17 are inserted into the positioning portions 15 of the hub components 11A on the base end and tip end sides of the two units. In the second embodiment, by inserting the positioning member 17 into the positioning portion 15 of the hub component 11A, the positioning member 17 acts as the axis of the hinge. The hub component 11A is rotated around the positioning portion 15 to position the connecting portion 14 of the unit at a predetermined position on the connecting plate HP. In this case, the connecting portion 14 of the hub component 11A coincides with the connecting plate HP at only one point on the circular orbit. Thereafter, the process of fixing the connecting portion 14 of the hub component 11A to the unit is repeated.

[0056] In the second fixing process, the multiple hub components 11A whose positions have been determined are fixed in an annular shape by the connecting plate HP. After that, the positioning members 17 are detached from the hub components 11A. This is because the hub components 11A cannot operate if the positioning members 17 are attached to them.

[0057] In this parallel link mechanism 2A, each unit A, B, and C is individually fixed by a connecting plate HP, which is a hub connecting member, and as long as two units remain to maintain the parallel link mechanism 2A, the other units can be removed. This improves maintainability compared to conventional structures. In addition, the same effects as those of the parallel link mechanism of the first embodiment are achieved.

[0058] [Third embodiment: Figs. 18 to 23B] As shown in FIGS. 18 to 23B, the parallel link mechanism 2B is made up of four structurally equivalent units. Increasing the number of units improves the rigidity of the entire parallel link mechanism. Even if the number of units changes, the center points of the spherical links on the base end and tip end sides remain the same. As shown in FIG. 21, the parallel link mechanism 2B of the third embodiment also includes connecting plates (hub connecting members) HP on the base end and tip end sides that connect multiple hub constituent members 11A.

[0059] As shown in Figure 18, when four units of the parallel link mechanism 2B are rotatably connected, the hub components form parallel links, and the shape of the link hub is not uniquely determined. However, the connecting plate HP fixes the central axes of each rotation pair at a position where they intersect at the center point of the spherical link. The parallel link mechanism 2B also uses a rod-shaped positioning member 17 with a circular cross-section insertion portion 17a during assembly. As shown in Figure 21, the connecting plate HP, which is a hub connecting member, has positioning portions 20 evenly spaced around its outer periphery. As shown in Figures 23A and 23B, by placing the outer periphery of the positioning member 17 against the positioning portions 20 of the connecting plate HP, it is easy to align the connecting plate HP with the hub component 11A, as shown in Figure 18. The assembly method is the same as in the second embodiment.

[0060] Although the embodiments of the present invention have been described above, the disclosed embodiments are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0061] 1...link actuator, 2, 2A, 2B...parallel 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, 11, 11A...hub constituent member, 12...hub connecting member, HP...connecting plate (hub connecting member), 13...revolute pair portion, 14...connecting portion, 15...positioning portion

Claims

1. A parallel 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 as to be able to change its posture, 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, the base-side link hub and the tip-side link hub each include a plurality of hub constituent members and a hub connecting member that connects these hub constituent members in an annular shape; Each of the hub component members is a parallel link mechanism having a rotational pair that rotatably connects the base-end link member or the tip-end link member, a connecting portion that fixes the hub component members to each other with the hub connecting member, and a positioning portion that positions the hub component members to each other.

2. 2. The parallel link mechanism according to claim 1, wherein the positioning portion of the hub component member on the base end side and the positioning portion of the hub component member on the tip end side are on the same straight line.

3. 3. The parallel link mechanism according to claim 1, wherein the base-side link hub and the tip-side link hub each have three of the hub constituent members.

4. 3. The parallel link mechanism according to claim 1, wherein the connecting portion of the hub component member also serves as the positioning portion.

5. 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 a base-side link member, a central link member, and a tip-side link member, the base-side link hub and the tip-side link hub each include a plurality of hub constituent members and a hub connecting member that connects these hub constituent members in an annular shape; 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 temporary fixing process in which the process of temporarily fixing the base end side hub components of the two units together and the tip end side hub components of the two units together are repeated to temporarily fix the required number of hub components together; a fixing step of fixing the plurality of hub constituent members in an annular shape by the hub connecting member.

6. 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 a base-side link member, a central link member, and a tip-side link member, the base-side link hub and the tip-side link hub each include a plurality of hub constituent members and a hub connecting member that connects these hub constituent members in an annular shape; 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 first fixing step of fixing the base end side hub component member and the tip end side hub component member of one of the units to the hub connecting member, respectively; a coupling step of rotatably coupling the hub components of the two units using a positioning member; a second fixing step of fixing the plurality of hub constituent members in an annular shape by the hub connecting member.

7. 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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