Joint mechanism

Abstract

To avoid interference between wire ropes even when a second joint part is rotated relative to a first joint part at an angle more than a prescribed angle.SOLUTION: A joint mechanism comprises: a first joint part; a second joint part which is connected with the first joint part through a connection member in which the second joint part is relatively rotatable around an axis line of the connection member; a plurality of wires which are linearly arrayed at one end side, extended from the first joint part to the second joint part, and stretchedly attached to the second joint part in a circumferential shape at the other side; and an off-set member which is arranged between the first joint part and the second joint part, offsets wires linearly arrayed at the one end by each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a joint mechanism for a robot or the like. [Background technology]

[0002] A joint mechanism is known which includes a first joint portion, a second joint portion connected to the first joint portion via a connecting member so as to be rotatable relative to the first joint portion around the axis of the connecting member, and a plurality of wires, one end of which is aligned in a straight line and extends from the first joint portion to the second joint portion and the other end of which is fixed circumferentially to the second joint portion and is pulled (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6545768 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above joint mechanism, when the second joint portion rotates relatively to the first joint portion by a certain angle or more, there is a risk that the wires may interfere with each other.

[0005] The present invention has been made in consideration of these problems, and its main object is to provide a joint mechanism that can avoid interference between wires even if the second joint portion rotates relative to the first joint portion by more than a certain angle. [Means for solving the problem]

[0006] In order to achieve the above object, one aspect of the present invention is to A first joint portion; a second joint portion connected to the first joint portion via a connecting member so as to be relatively rotatable around an axis of the connecting member; A plurality of wires, one end of which is arranged in a straight line and extends from the first joint portion to the second joint portion, and the other end of which is circumferentially attached to the second joint portion and is pulled; An offset member provided between the first joint portion and the second joint portion, through which the wire passes, offsetting one end sides of the wires arranged in a straight line from each other; A joint mechanism having It is. In this embodiment, The offset member may circumferentially offset one end side of the linearly arranged wires. In this embodiment, The offset member may offset one end side of the linearly arranged wires in a concentric circle with the circle formed when the other end side of the wires is fixed circumferentially. In this embodiment, The first joint may be an elbow joint of a robot, and the second joint may be a wrist joint of a robot. Effect of the Invention

[0007] According to the present invention, it is possible to provide a joint mechanism capable of preventing interference between wires even when the second joint portion rotates relatively to the first joint portion by a certain angle or more. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of a joint mechanism according to the present embodiment. [Diagram 2] FIG. 13 is a diagram showing wire interference. [Diagram 3] FIG. 13 is a top view of the wire from the elbow joint side to the wrist joint side. [Figure 4] FIG. 13 is a diagram showing a state in which four wires are offset by an offset member. [Diagram 5] 13A and 13B are diagrams illustrating simulation results of interference of wires according to the embodiment. [Figure 6]13A and 13B are diagrams illustrating simulation results of interference of wires according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A joint mechanism according to this embodiment is provided in, for example, a robot arm. Fig. 1 is a perspective view showing a schematic configuration of the joint mechanism according to this embodiment.

[0010] The joint mechanism 1 in this embodiment includes, for example, an elbow joint section 2, a wrist joint section 3 connected to the elbow joint section 2 via a connecting member (not shown) so as to be rotatable relative to the elbow joint section 2 around the axis of the connecting member, and a plurality of wires 4 extending from the elbow joint section 2 toward the wrist joint section 3 and being pulled.

[0011] The elbow joint 2 is a specific example of a first joint. The wrist joint 3 is a specific example of a second joint. The connecting member is formed of, for example, a link or a frame. The wrist joint 3 is configured to be rotatable relative to the elbow joint 2 around the axis of the connecting member, i.e., around the yaw axis.

[0012] For example, four wires 4 are provided from the elbow joint 2 to the wrist joint 3. Note that in this embodiment, four wires 4 are provided, but the present invention is not limited to this, and any number of wires 4 may be provided.

[0013] A pulley 21 is provided at the elbow joint 2. One end of each wire 4 is wound around the pulley 21. Therefore, one end of each wire 4 is aligned horizontally in a straight line at a predetermined interval, extending from the pulley 21 of the elbow joint 2 towards the wrist joint 3. Meanwhile, the other end of each wire 4 is circumferentially attached to an end of the wrist joint 3. When one end of each wire 4 is pulled, the wrist joint 3 is configured to be rotationally driven around the roll axis or pitch axis, for example.

[0014] Here, in the conventional arrangement of four wires 4 as shown in Fig. 2(a), when the wrist side is rotated largely around the yaw axis relative to the elbow side, there is a risk that the wires 4 may interfere with each other. For this reason, the range of rotation around the yaw axis is limited to a range of 180 degrees, from -90 degrees shown in Fig. 2(b) to +90 degrees shown in Fig. 1(c).

[0015] However, in an actual person, the range of rotation of the wrist joint relative to the elbow joint about the yaw axis is approximately 270 degrees, which is wider than the above range, and it is desirable to realize a wider range of rotation about the yaw axis.

[0016] In contrast, the joint mechanism 1 according to this embodiment, as shown in FIG. 1, is provided between the elbow joint portion 2 and the wrist joint portion 3, and further includes an offset member 5 through which a wire 4 passes to offset one end of the wires 4 arranged in a straight line from one another.

[0017] Between the elbow joint 2 and the wrist joint 3, the offset member 5 offsets the wires 4 so as to avoid interference between the wires 4 even if the wrist joint 3 rotates relative to the elbow joint 2 by a certain angle or more. Therefore, even if the wrist joint 3 rotates relative to the elbow joint 2 by a certain angle or more, interference between the wires 4 can be avoided.

[0018] The offset member 5 is a substantially cylindrical member, and has four through holes 51 formed circumferentially corresponding to the four wires 4. The through holes 51 extend in the yaw axis direction. Each wire 4 extending from the pulley 21 of the elbow joint 2 passes through the through holes 51 of the offset member 5, and is offset circumferentially. The circumferentially offset wires 4 extend in this state, and are attached circumferentially to the wrist joint 3.

[0019] Next, a detailed description will be given of the above-mentioned offset method of the wire 4. Fig. 3 is a top view of the wire seen from the elbow joint side to the wrist joint side.

[0020] First, for ease of understanding, assume that the two wires L1 and L2 are offset. As shown in Fig. 3(a), when the wrist joint 3 is rotated 90 degrees around the yaw axis relative to the elbow joint 2, the thickness of the wires L1 and L2 causes an overlapping area between the motion area X1 of the wire L1 and the motion area X2 of the wire L2, causing mutual interference.

[0021] On the other hand, as shown in Fig. 3(b), the ends of the wires L1 and L2 on the elbow joint side are offset from each other. In this case, there is no overlapping area between the motion area X1 of the wire L1 and the motion area X2 of the wire L2, and the wires L1 and L2 do not interfere with each other.

[0022] Next, assume that the four wires L1, L2, L3, and L4 are offset. As shown in Fig. 3(c), the ends of the wires L1, L2, L3, and L4 on the elbow joint side are offset circumferentially so as to be separated from each other. In this case, there is no overlapping area among the motion area X1 of the wire L1, the motion area X2 of the wire L2, the motion area X3 of the wire L3, and the motion area X4 of the wire L4, and the wires L1, L2, L3, and L4 do not interfere with each other.

[0023] 4 is a diagram showing a state in which four wires are offset by an offset member. The four wires L1, L2, L3, and L4 are aligned in a straight line and extend from the pulley 21 of the elbow joint 2 toward the wrist joint 3.

[0024] As described above, four through holes are formed circumferentially in the offset member 5 provided between the wrist joint 3 and the elbow joint 2, corresponding to the wires L1, L2, L3, and L4. Therefore, when the wires L1, L2, L3, and L4 extending from the pulley 21 of the elbow joint 2 pass through these through holes, the wires L1, L2, L3, and L4 are offset circumferentially and extend to the wrist joint 3 in a circumferentially offset state, with the other ends attached circumferentially to the wrist joint 3.

[0025] The offset member 5 preferably offsets one end of the wires L1, L2, L3, and L4 arranged in a straight line so as to be concentric with the circle formed when the other end of the wires L1, L2, L3, and L4 is circumferentially fixed to the wrist joint 3. This makes it possible to avoid interference between the wires L1, L2, L3, and L4 even if the wrist joint 3 rotates relative to the elbow joint 2 by a certain angle or more.

[0026] The offset member 5 is fixed to, for example, a link. Therefore, when the wrist joint 3 is rotated relative to the elbow joint 2 around the yaw axis, the section Y of the wires L1, L2, L3, and L4 from the pulley 21 of the elbow joint 2 to the offset member 5 does not move as shown in Figure 4, so there is no mutual interference.

[0027] On the other hand, the portions of the wires L1, L2, L3, and L4 from the offset member 5 to the wrist joint 3 move within the range of the motion area. However, as described above, because they are circumferentially offset by the offset member 5, the motion area X1 of the wire L1, the motion area X2 of the wire L2, the motion area X3 of the wire L3, and the motion area X4 of the wire L4 do not overlap as shown in Fig. 4, and the wires L1, L2, L3, and L4 do not interfere with each other.

[0028] Figures 5 and 6 are diagrams showing the results of a simulation of wire interference according to this embodiment. In Figures 5 and 6, the left side of the arrows shows the initial state of the wires L1, L2, L3, and L4, and the right side of the arrows shows the state of the wires L1, L2, L3, and L4 after they are moved. Figure 5 shows the wires L1, L2, L3, and L4 rotated counterclockwise, and Figure 6 shows the wires L1, L2, L3, and L4 rotated clockwise.

[0029] As shown in FIG. 5, even if the wrist joint 3 is rotated relative to the elbow joint 2 around the yaw axis from the initial state and each of the wires L1, L2, L3, and L4 is rotated counterclockwise by −135 deg, it can be seen that interference between the wires L1, L2, L3, and L4 can be avoided.

[0030] 6, even if the wrist joint 3 is rotated around the yaw axis relative to the elbow joint 2 from the initial state and the wires L1, L2, L3, and L4 are rotated clockwise by +180 degrees, it can be seen that interference between the wires L1, L2, L3, and L4 can be avoided. In this way, by offsetting the wires L1, L2, L3, and L4 circumferentially using the offset member 5 according to this embodiment, interference between the wires L1, L2, L3, and L4 can be avoided even if the wrist joint 3 is rotated around the yaw axis relative to the elbow joint 2 within a wide range of -135 degrees to +180 degrees (angle range 315 degrees).

[0031] As described above, the joint mechanism 1 according to this embodiment further includes an offset member 5 that is provided between the elbow joint portion 2 and the wrist joint portion 3 and through which the wire 4 passes to offset one end of the wires 4 arranged in a straight line from each other. This makes it possible to avoid interference between the wires 4 even if the wrist joint portion 3 rotates relatively to the elbow joint portion 2 by a certain angle or more.

[0032] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0033] 1 joint mechanism, 2 elbow joint, 3 wrist joint, 4 wire, 5 offset member, 21 pulley, 51 through hole

Claims

1. A first joint portion; a second joint portion connected to the first joint portion via a connecting member so as to be relatively rotatable around an axis of the connecting member; a plurality of wires, one end of each of which is arranged in a straight line and extends from the first joint portion to the second joint portion, and the other end of each of which is circumferentially attached to the second joint portion and is pulled; an offset member provided between the first joint portion and the second joint portion, through which the wire passes to offset one end sides of the wires arranged in a straight line from each other; Equipped with The offset member is The ends of the wires arranged in a straight line are offset circumferentially away from each other; One end side of the wires arranged in a straight line is offset concentrically with the circle formed when the other end side of the wires is fixed in a circumferential shape. Joint mechanism.

2. The joint mechanism according to claim 1, The first joint portion is an elbow joint portion of a robot, and the second joint portion is a wrist joint portion of a robot. Joint mechanism.

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