Patent Grant
11548142
The present disclosure relates to parallel link devices, and more particularly to a parallel link device for use in an industrial robot, a device for astronomical purposes and the like.
An example of conventional parallel link devices for use in handling a heavy object is disclosed in Japanese Patent Laid-Open No. 11-104987. Specifically, a non-extendable arm has one end coupled to a fixed-side member with a slip block interposed therebetween, and the other end coupled to a movable-side member with a bearing portion interposed therebetween. The movable-side member can be moved by moving the slip block in a height direction (Z direction).
In Japanese Patent Laid-Open No. 11-104987, moving the movable-side member upward decreases the spacing in the height direction between the movable-side member and the facing fixed-side member, but causes an inclined guide portion to extend upward beyond the fixed-side member. Thus, the extending length of the inclined guide portion protruding in the Z direction is added to the Z direction spacing between the fixed-side member and the movable-side member. Accordingly, the Z direction length of the entire parallel link device including the protruding length of the inclined guide portion, namely, the required space, increases. In this manner, in the case of the device of Japanese Patent Laid-Open No. 11-104987, the space cannot be saved even when the movable-side member moves upward by large amount of movement and the height direction spacing between the movable-side member and the fixed-side member is reduced.
The present disclosure has been made in view of the problem described above, and an object of the present disclosure is to provide a parallel link device whose height can be reduced particularly when a movable-side member is brought closer to a fixed-side member, and in which an amount of stroke of the movable-side member can be increased.
A parallel link device of the present disclosure includes a fixed-side member, a movable-side member, six links, and a plurality of slide mechanisms. Each of the six links has one end connected to the movable-side member with at least two rotational degrees of freedom and the other end connected to the fixed-side member with at least two rotational degrees of freedom. A connection point of the other end and the fixed-side member is movable with respect to the fixed-side member. Each of the six links has five rotational degrees of freedom and a predetermined length. Each of the plurality of slide mechanisms is provided on a side face of the fixed-side member and holds the other end of the link movable along the slide mechanism within a predetermined range.
According to the present disclosure, with the six links and the plurality of slide mechanisms, the height can be reduced particularly when the movable-side member is brought closer to the fixed-side member, and an amount of stroke of the movable-side member can be increased.
Embodiments of the present disclosure are described hereinafter with reference to the drawings.
Referring first to
An upper main surface 1a and an opposed lower main surface 1b of fixed-side table 1 have a polygonal shape in plan view, and particularly have a regular triangular shape here. Main surface 1b may have a triangular shape other than a regular triangular shape, but desirably has a regular triangular shape because six links 3 can be moved in the same way. An upper main surface 2a and an opposed lower main surface 2b of movable-side table 2 also have a planar shape which is substantially a regular triangular shape, and have a hexagonal planar shape to be exact by being linearly chamfered at the corners. Fixed-side table 1 is arranged above movable-side table 2 such that main surface 1b of fixed-side table 1 and main surface 2a of movable-side table 2 face each other having a spacing between them with respect to the Z direction.
Fixed-side table 1 does not move but is fixed at a predetermined position with respect to the Z direction. In contrast, movable-side table 2 moves relative to fixed-side table 1 mainly in the Z direction that intersects an X-Y plane parallel to the main surfaces of fixed-side table 1 and movable-side table 2. Namely, as movable-side table 2 moves upward or downward, the distance between movable-side table 2 and fixed-side table 1 decreases or increases. Movable-side table 2 can also move in the X-Y plane within a range predetermined depending on its position in the Z direction. Movable-side table 2 cannot move in any of the X direction and the Y direction when at its lowest position in the Z direction. As the position in the Z direction moves up from the lowest position, movable-side table 2 is allowed to move in both the X direction and the Y direction. Movable-side table 2 can also be inclined within a range predetermined depending on its position in the Z direction. Ranges in which movable-side table 2 can move in the X direction and the Y direction are at their maxima around the middle in the Z direction, and decrease according as the movable-side table 2 moves upward from the position corresponding to the maximum ranges. Once movable-side table 2 reaches its highest position in the Z direction, it cannot move in any of the X direction and the Y direction. Parallel link device 100 utilizes this movement of movable-side table 2 to position movable-side table 2 with six degrees of freedom to an appropriate position in order to grip an object. And the parallel link device 100 is used for gripping the object, lifting and moving the object, and lowering and releasing the object after the movement, for example.
Although not depicted, movable-side table 2 is provided with a robot hand. The robot hand is a member for gripping an object and holding the object on the lower side of movable-side table 2. The upper side of fixed-side table 1 is provided with a movement mechanism (not shown) for moving the entire mechanism including slide mechanisms 4 and six links 3 which are described later. This entire mechanism is thus movable along a rail or the like provided on a building.
The robot hand attached is shaped to be suitable for the shape of an object to be gripped. When a plate-like object (not shown) is to be gripped, for example, a claw-like robot hand is provided from a side face corresponding to each side forming the triangular shape of movable-side table 2. The lower side of the plate-like object is supported by the robot hand, and the plate-like object is held between the robot hand and movable-side table 2. As a result, the height of the entire mechanism including six links 3 holding the plate-like object can be reduced. The reduced height of the entire mechanism including six links 3 allows the mechanism to pass through a portion with height limitations when moving on a rail or the like within a building, for example.
Link 3 is a member extending like an arm, and has a predetermined length, namely, a fixed length. Link 3 has one end, a link one end 3b, connected to movable-side table 2, and the other end, a link other end 3a, connected to fixed-side table 1. Particularly, link other end 3a is held by slide mechanism 4 provided on fixed-side table 1. Six links 3 connect fixed-side table 1 and movable-side table 2 in this manner.
Slide mechanism 4 is now described. Two slide mechanisms 4 are provided on each of three side faces of fixed-side table 1 existing from main surface 1a to main surface 1b in a thickness direction of fixed-side table 1. Two slide mechanisms 4 are provided at the same height of the side face so as to extend from the center to both sides, and slide mechanisms 4 are provided at a total of six locations on fixed-side table 1.
As shown particularly in
Driving block 4c is connected to link other end 3a of link 3 with a bearing portion 5 interposed therebetween. Driving block 4c is mounted so as to be engaged with driving rail 4b, thereby allowing link 3 connected to driving block 4c to move along the direction in which driving rail 4b extends. Driving block 4c can be driven with high rigidity and precision on driving rail 4b. In addition, the use of roller screw 4a for the movement of driving block 4c along the direction in which driving rail 4b extends allows for more precise movement. The position where link other end 3a connects may be moved by a mechanism different from roller screw 4a.
Link 3 is composed of an upper portion and a lower portion that are rotatably connected with a bearing portion 6 interposed therebetween. The upper portion is the side including link other end 3a.
Link one end 3b of link 3 is connected to a region on main surface 2a of movable-side table 2, which is near a linearly chamfered corner of the triangular shape in plan view, with a bearing portion 7 interposed therebetween.
Referring now to
Bearing portion 5 has a structure that allows link 3 to rotate around a rotation axis 1, as shown in
As shown in
Bearing portion 7 has a structure that allows link 3 to rotate around a rotation axis 3, as shown in
As shown in
With five rotation axis 1 to rotation axis 5 described above, each of six links 3 has a total of five rotational degrees of freedom. Each of six links 3 may have six or more rotational degrees of freedom.
Referring now to
As shown in
It is assumed that the uppermost portion of link 3 is fixed to the central portion in the Z direction of fixed-side table 1, and driving block 4c is provided at this central portion in the Z direction. A distance in the Z direction between the uppermost portion of link 3 and the uppermost surface of movable-side table 2 is represented by D. A length of each of two links 3 shown in
From the state of
The chain-double-dotted lines shown in
Although not depicted, when the position of the other end of link 3, namely, driving block 4c moves to an innermost driving position 9 which is the innermost position with respect to the X direction, that is, close to the center line as shown in
As described above, by moving driving block 4c and movable-side table 2 as indicated by arrows as shown in
The function and effect of the present embodiment is described.
The present embodiment has a structure in which link other ends 3a of six links 3 are held by and connected to slide mechanisms 4 extending along the three side faces of fixed-side table 1, and are movable by the linear guide mechanisms of slide mechanisms 4 within the ranges in which slide mechanisms 4 extend. In addition, link one ends 3b of six links 3 are connected to movable-side table 2.
As a result, movable-side table 2 is movable in the Z direction depending on movements of link other ends 3a along the directions in which slide mechanisms 4 extend. By moving movable-side table 2 upward to bring movable-side table 2 closer to fixed-side table 1, for example, the length in the Z direction of entire parallel link device 100 including fixed-side table 1 and movable-side table 2 can be reduced. Parallel link device 100 can be expanded and contracted with respect to the Z direction as shown in
Here, link other ends 3a are connected to fixed-side table 1, and link one ends 3b are connected to movable-side table 2. Thus, during upward movement of movable-side table 2, for example, link one ends 3b does not protrude below movable-side table 2, or link other ends 3a does not protrude above fixed-side table 1. That is, when the Z direction spacing between fixed-side table 1 and movable-side table 2 is reduced, the Z direction length of entire parallel link device 100 can be made more compact.
Meanwhile, by increasing particularly the values of lengths L and E as shown in
Parallel link device 100 in the present embodiment can provide both the compactness in the Z direction and the lengthened stroke during driving as described above, and is therefore highly practical and space-saving. When both the compactness and the lengthened stroke are attained, spacing D in the Z direction between fixed-side table 1 and movable-side table 2 can be basically expressed as H<D<F. Here, H represents a distance from lower main surface 1b of fixed-side table 1 to slide mechanism 4.
In parallel link device 100 in the present embodiment, link other end 3a moves in a direction in which each side of fixed-side table 1 extends, namely, in a direction within the X-Y plane. Thus, when the amounts of movement in the X and Y directions of link other end 3a increases particularly to realize the lengthened stroke, length L as shown in
Since parallel link device 100 has six links 3 connecting fixed-side table 1 and movable-side table 2, movable-side table 2 to which six links 3 are connected can be positioned with a total of six degrees of freedom. However, when links 3 are driven in order to move movable-side table 2 in the Z direction, for example, shafts of links 3 may be twisted and the movement of links 3 is limited. To overcome such twist of the shafts of links 3 and suppress the limitation of movement of links 3 caused by the twist, each of links 3 has five rotational degrees of freedom in the present embodiment. As a result, movable-side table 2 can move with six degrees of freedom, by combination not only of movements in directions along the X, Y and Z directions but also of rotations around the axes extending in the X, Y and Z directions, for example.
To realize the five rotational degrees of freedom of link 3, in the present embodiment, link 3 has link one end 3b and link other end 3a connected to movable-side table 2 and fixed-side table 1, respectively, by the connector including a gimbal mechanism having two rotational degrees of freedom, and is also provided with bearing portion 6 at the central portion in order to have one rotational degree of freedom. As a result, the positioning of movable-side table 2 with six degrees of freedom is possible.
In two links 3 having two link other ends 3a moving on the same side face of fixed-side table 1, their two link one ends 3b may connect to movable-side table 2 in any positional relation. Link one ends 3b of links 3 having link other ends 3a moving on different side faces may also connect to movable-side table 2 in any positional relation. Movable-side table 2 may have any shape as long as six link one ends 3b can be connected thereto and movable-side table 2 has an appropriate thickness. When two link one ends 3b of two links 3 having two link other ends 3a moving on the same side face of fixed-side table 1 are mounted close to each other at a corner of regular triangular main surface 2a of movable-side table 2 as in this first embodiment, the amount of stroke of movable-side table 2 can be made longer, and when moving or inclining movable-side table 2 in the X-Y plane, the differences among movable ranges for different directions in the X-Y plane can be reduced.
In states other than the state where movable-side table 2 is lowered to the lowermost position, the positions in the X and Y directions of movable-side table 2 as well as the inclination of movable-side table 2 with respect to the X-Y plane can be changed. Ranges in which the positions and inclination can be changed are at their maxima around D=F/2 as shown in
In parallel link device 200, a fixed-side table 11 is different from fixed-side table 1 of the first embodiment in its planar shape. An upper main surface 11a and an opposed lower main surface 11b of fixed-side table 11 have a regular hexagonal shape in plan view. Main surface 11b may have a hexagonal shape other than a regular hexagonal shape, but desirably has a regular hexagonal shape because six links 3 can thereby be moved in the same way. An upper main surface 12a and an opposed lower main surface 12b of a movable-side table 12 have a regular triangular shape as in the first embodiment. A straight line passing through the center of gravity of main surfaces 11a and 11b of fixed-side table 11 and parallel to a Z axis passes through the center of gravity of main surfaces 12a and 12b of movable-side table 12. The vertices of the regular hexagon of main surfaces 11a and 11b of fixed-side table 11 exist on planes each including the Z axis and a straight line from the center of gravity of main surface 12a of movable-side table 12 toward each of the vertices of the regular triangle. One slide mechanism 4 is provided on each of the six side faces of fixed-side table 11. As slide mechanism 4 moves, an angle formed between a segment obtained by projecting link 3 on the X-Y plane and the side face of fixed-side table 11 varies. To prevent contact between link 3 and fixed-side table 11 by this angle variation, link other end 3a is provided at a position farther from the side face of fixed-side table 11 than in the first embodiment.
The fixed-side table of parallel link device 200 may have a triangular shape or a hexagonal shape as long as it is a polygonal shape in plan view. The movable-side table functions equally with any of the shapes, and operates similarly to when it has a triangular shape as shown in
In the first embodiment, fixed-side table 1 has a regular triangular shape in plan view, and two slide mechanisms 4 are arranged on each of the three side faces of fixed-side table 1. In the second embodiment, fixed-side table 1 has a regular hexagonal shape in plan view, and one slide mechanism 4 is arranged on each of the six side faces of fixed-side table 11. As to the arrangement of the slide mechanisms onto the fixed-side table having a polygonal shape in plan view, the number of slide mechanisms may vary from side face to side face. Slide mechanisms 4 may be arranged in any manner as long as six slide mechanisms 4 can be arranged so that each of slide mechanisms 4 can move link other end 3a within a required range. Slide mechanism 4 may also be arranged on the main surface of fixed-side table 11. An angle between the side face of fixed-side table 11 and lower main surface 11b does not need to be 90 degrees.
When slide mechanisms movable on curves are used, the fixed-side table may have a shape including a curve in plan view. Six links 3 may not have the same length. When the fixed-side table has a shape which is neither a regular triangular shape nor a regular hexagonal shape in plan view, the six links need to have different lengths in order for the movable-side table to be horizontal when lowered to the lowermost position.
The present embodiment is different in the structure of the bearing portion connecting link 3 and fixed-side table 1 or movable-side table 2 as is discussed below, and otherwise basically has a structure similar to that of parallel link device 100 in the first embodiment. Thus, the same components as those of parallel link device 100 are designated by the same reference signs and description thereof is not repeated.
Bearing portion 10 as a spherical bearing allows link 3 to rotate with three degrees of freedom. The three degrees of freedom mean allowing rotation in any direction with respect to a rotation axis 6, a rotation axis 7 and a rotation axis 8 orthogonal to one another shown in
The function and effect of the present embodiment is described. The present embodiment has the following function and effect in addition to those in the first embodiment.
As described above, one of link other end 3a and link one end 3b connected to bearing portion 10 as a spherical bearing in the present embodiment has three rotational degrees of freedom with respect to fixed-side table 1 or movable-side table 2. As a result, even when the other of link other end 3a and link one end 3b is connected by bearing portions 5 and 7 as a gimbal mechanism in the first embodiment, five rotational degrees of freedom can be attained from a combination of these link other end 3a side and the link one end 3b side. Bearing portion 6 at the central portion in the direction in which link 3 extends can thereby be omitted, thereby reducing the number of components of the bearing portions. The structure of the entire device can thereby be simplified.
As described above, the connections of link one end 3b and link other end 3a to fixed-side table 1 and movable-side table 2 may be made with two rotational degrees of freedom, or may be made with three rotational degrees of freedom.
The features of the components in each embodiment listed above may be combined as appropriate as long as no technical contradictions arise.
It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present disclosure is defined by the terms of the claims, rather than the description above, and is intended to include any modifications and omissions within the scope and meaning equivalent to the terms of the claims.
1, 11 fixed-side table; 1a, 1b, 2a, 2b, 11a, 11b, 12a, 12b main surface; 2 movable-side table; 3 link; 3a link other end; 3b link one end; 4 slide mechanism; 4a roller screw; 4b driving rail; 4c driving block; 5, 6, 7, 10 bearing portion; 8 outermost driving position; 9 innermost driving position; 100, 200 parallel link device.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/082999 | 11/25/2015 | WO |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2017/090105 | 6/1/2017 | WO | A |
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| Number | Date | Country | |
|---|---|---|---|
| 20180326587 A1 | Nov 2018 | US |
