WO2018173278A1

WO2018173278A1 - Manipulator joint structure

Info

Publication number: WO2018173278A1
Application number: PCT/JP2017/012114
Authority: WO
Inventors: 裕行高山; 紀明山中
Original assignee: オリンパス株式会社
Priority date: 2017-03-24
Filing date: 2017-03-24
Publication date: 2018-09-27

Abstract

In order to ensure a large swing angle while suppressing changes in the path length of a wire for driving a mechanism on the tip side, this joint structure (1) comprises: a first member (2) that is provided with a first rolling part (21); a second member (3) that is provided with a second rolling part; n mutually parallel shafts (51, 52, 53) that constitutes n bending joint units between the second member and the first member, and n-1 link members (61, 62) that are disposed between the shafts so as to be able to swing and are provided with respective rolling parts (61a, 62a) on at least one end; and a pulley that is rotatably supported by the shafts and over which a wire passes. The first rolling part is disposed so as to be in rolling contact with the rolling part of the second link member, the second rolling part is disposed so as to be in rolling contact with the rolling part of the (n-2)th link member, and the rolling part of the (m)th link member is disposed so as to be in rolling contact with the rolling part of the (m+2)th link member.

Description

Manipulator joint structure

The present invention relates to a joint structure of a manipulator.

The first member and the second member that swings relative to the first member are brought into rolling contact with the gears fixed to the two members, and the two axes of the two gears are connected to each other by a link. A joint structure of a manipulator is known in which a pulley is arranged between the pulleys so as to meander a wire for driving the tip side mechanism (see, for example, Patent Document 1). ).

Japanese Patent No. 3912251

However, although the joint structure of Patent Document 1 can suppress a change in the path length of the wire due to the swing of the second member relative to the first member, the rolling angle range of the two gears is the swing angle of the second member relative to the first member. Therefore, there is an inconvenience that it is difficult to ensure a large swing angle due to interference between the first member and the second member.
The present invention has been made in view of the above-described circumstances, and provides a joint structure for a manipulator that can secure a large swing angle while suppressing a change in path length of a wire for driving a distal end side mechanism. The purpose is that.

One embodiment of the present invention includes a first member provided with a first rolling portion, a second member provided with a second rolling portion, and n pieces between the second member and the first member. First to n-th n parallel shafts in order from the side of the first member constituting the (n ≧ 3) bending joint portion, and at least one end portion disposed so as to be swingable between the shafts. The first to (n-1) th n-1 link members in order from the side of the first member provided with rolling portions, and pulleys that are rotatably supported by the shafts and over which the wires are passed. The first rolling part is disposed so as to be in rolling contact with the rolling part of the second link member, and the second rolling part is the rolling of the (n-2) th link member. Before the m-th (1 ≦ m <n−3) link member. Rolling unit, the m + 2 of the link member and the rolling portion and the rolling contact is so arranged by being Manipyure of - a joint structure of data.

According to this aspect, when the second member is swung in one direction with respect to the first member, the first to n−1th link members disposed between the first member and the second member are The rolling portions provided in the link members are swung while being in rolling contact with the rolling portions of the adjacent link members, the first rolling portion, or the second rolling portion. That is, when the second member is swung by a predetermined angle with respect to the first member, it is sufficient that the link member between them is swung by a smaller angle, so that the relative link between adjacent link members is sufficient. The swing angle is kept small and does not interfere with each other.

Conversely, by increasing the relative swing angle of adjacent link members within a range that does not interfere with each other, the second member can be swung with a large swing angle with respect to the first member. A large swing angle can be secured while suppressing a change in the path length of the wire by meandering the wire around the pulley provided on each shaft.

In the above aspect, the following conditional expression may be satisfied.

Here, Rkj (k = 1, 2, j = 1, 2,..., N) is the k-th rolling portion and the rolling portions of the group of the link members that are sequentially in rolling contact with the k-th rolling portion. , Ri (i = 1, 2,..., N) of the rolling portion arranged around the j-th shaft is a radius of each of the pulleys provided on the i-th shaft. .
By doing so, it is possible to prevent a change in the path length of the wire spanned over the pulley.

Moreover, in the said aspect, you may satisfy the following conditional expressions.
When n is an even number, R11 ≧ R12, R13 ≧ R14,..., R1 (m−1) ≧ R1m, R1n ≧ R1 (n−1), R1 (n−2) ≧ R1 (n−3),. R1 (m + 2) ≧ R1 (m + 1), R23 ≧ R24,..., R2 (m−1) ≧ R2m, R2 (n−2) ≧ R2 (n-3),..., R2 (m + 2) ≧ R2 (m + 1) , N is an odd number, R11 ≧ R12, R13 ≧ R14,..., R1 (m−1) ≧ R1m, R1 (n−2) ≧ R1 (n-3),..., R1 (m + 2) ≧ R1 (m + 1) , R23 ≧ R24,..., R2 (m−1) ≧ R2m, R2 (n) ≧ R2 (n−1),..., R2 (m + 2) ≧ R2 (m + 1).
Here, Rkj (k = 1, 2, j = 1, 2,..., N) is the k-th rolling portion and the rolling portions of the group of the link members that are sequentially in rolling contact with the k-th rolling portion. Is the radius of the rolling part arranged around the j-th shaft, and m is an integer that minimizes the following function f (m).

In this way, the second member can be swung so as to be disposed at a position close to the first member without making a large turn with respect to the first member.

Moreover, in the said aspect, you may satisfy the following conditional expressions.
When n is an even number, R11≥R13≥R15≥ ... ≥R1 (n-1), R12≥R14≥R16≥ ... ≥R1n, R23≥R25≥R27≥ ... ≥R2 (n-1), R22≥R24≥ R26≥ ... ≥R2 (n-2), when n is an odd number, R11≥R13≥R15≥ ... ≥R1 (n-2), R12≥R14≥R16≥ ... ≥R1 (n-1), R23≥R25 ≥R27≥ ... ≥R2n, R22≥R24≥R26≥ ... ≥R2 (n-1).
Here, Rkj (k = 1, 2, j = 1, 2,..., N) is the k-th rolling portion and the rolling portions of the group of the link members that are sequentially in rolling contact with the k-th rolling portion. The radius of the rolling portion arranged around the j-th shaft.
By doing in this way, the diameter of the second member can be reduced with respect to the first member.

Moreover, in the said aspect, the said rolling part may be a gear part and Rkj may be a pitch circle radius.
In the above aspect, n = 3, R11: R12: R22: R23 = 2: 1: 1: 2, and r1 = r2 = r3.
In this way, three bending joints are formed between the first member and the second member, and the length of the wire routed so as to meander to the adjacent pulley extends the joint structure. It is possible to prevent a change between the bent state and the curved state.

According to the present invention, it is possible to secure a large swing angle while suppressing a change in the path length of the wire for driving the distal end side mechanism.

1 is a partial front view of a manipulator including a joint structure according to a first embodiment of the present invention. It is a disassembled perspective view explaining the component of the joint structure of FIG. It is a front view which shows the joint structure of FIG. FIG. 4 is a cross-sectional view taken along line AA in FIG. 3 showing a longitudinal section of the joint structure in FIG. 3. FIG. 5 is a sectional view taken along the line CC of FIG. 4 of the joint structure of FIG. FIG. 5 is a cross-sectional view taken along the line BB in FIG. 4 of the joint structure of FIG. 3. FIG. 6 is a DD cross-sectional view of the joint structure of FIG. 3 in FIG. FIG. 5 is a sectional view taken along the line CC in FIG. 4 showing a state in which the joint structure of FIG. 3 is curved. FIG. 5 is a cross-sectional view taken along the line BB in FIG. 4 showing a state in which the joint structure of FIG. 3 is curved. FIG. 6 is a DD cross-sectional view in FIG. 4 showing a state in which the joint structure of FIG. 3 is curved. FIG. 2 is a diagram showing a first group of the joint structure of FIG. 1 having n bent joints. It is a figure which shows the 2nd group of the joint structure of FIG. 1 which has n bending | flexion joint parts. FIG. 12 is a view showing a state in which wires are meandered and stretched over pulleys provided on each shaft of the joint structure of FIG. 11. It is a figure which shows the bending state of the joint structure of FIG. 1 which has five bending joint parts. It is a reference figure which shows the case where the pitch circle radius of all the gear parts is the same. It is a figure which shows the 1st group of the joint structure which concerns on the 2nd Embodiment of this invention. It is a figure which shows the 2nd group of the joint structure of FIG.

A joint structure 1 of a manipulator 100 according to a first embodiment of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, the joint structure 1 according to the present embodiment is disposed at a middle position in the longitudinal direction of a long manipulator 100 having a treatment portion 101 at the distal end, and is a first member on the proximal end side. 2, the second member 3 on the distal end side is bent about an axis perpendicular to the longitudinal axis of the manipulator 100.

As shown in FIG. 2, the joint structure 1 includes a first member 2, a second member 3, and n parallel bending axes (shafts) constituting n bending joint portions 4 therebetween. 5, n−1 link members 6, and a pulley 7 rotatably attached to each bending shaft 5. As shown in FIG. 4, reference numeral 8 is a collar for rotatably attaching the pulley 7 to each bending shaft 5, and reference numeral 9 is a cap fixed to both ends of the bending shaft 5.

In the present embodiment, the case where n = 3 will be described as an example. Hereinafter, the numbers of the bending shaft 5, the link member 6 and the pulley 7 are assigned so as to increase in order from the first member 2 to the second member 3 as shown in FIGS. 3 and 4. And

As shown in FIG. 5, the first member 2 has a first gear portion (first rolling portion) formed in a part of the circumferential direction around the first bending shaft (shaft) 51 disposed at one end. 21 is provided.
As shown in FIG. 6, the second member 3 is a second gear portion (second rolling portion) formed in a part of the circumferential direction around the third bending shaft (shaft) 53 disposed at one end. 31 is provided.

As shown in FIG. 6, the first link member (link member) 61 is rotatably attached around the first bending shaft 51 and the second bending shaft (shaft) 52, and the second member. A gear portion (rolling portion) 61a that meshes with the third second gear portion 31 is provided at one end.
As shown in FIG. 5, the second link member (link member) 62 is rotatably attached around the second bending shaft 52 and the third bending shaft 53, and A gear portion (rolling portion) 62a that meshes with one gear portion 21 is provided at one end.

When the first gear portion 21 provided on the first member 2 and the gear portion 62a meshing with the first gear portion 21 are used as the first group, the first group 2 is rotated around the first bending axis 51 of the first group. The pitch circle radius of the arranged first gear portion 21 is R11, and the pitch circle radius of the gear portion 62a (of the second link member 62) provided around the second bending shaft 52 of the first group is R12. Call it. Further, when the second gear portion 31 provided on the second member 3 and the gear portion 61a meshing with the second gear portion 31 are used as the second group, the second bending shaft 52 of the second group is used. The pitch circle radius of the gear portion 61a (of the first link member 61) provided around is R22, and the pitch circle radius of the second gear portion 31 disposed around the third bending axis 53 of the second group Is called R23.

At this time, the following conditional expression (1) is satisfied.
R11: R12: R22: R23 = 2: 1: 1: 2 (1)
Further, assuming that the radius r1 of the first pulley (Puri) 71, the radius r2 of the second pulley (Puri) 72, and the radius r3 of the third pulley (Puri) 73 are r1. , R2 and r3 satisfy the following conditional expression (2).
r1 = r2 = r3 (2)

As shown in FIGS. 3 and 4, each of the

pulleys

71, 72, 73 has a circumferential groove around which

wires

10 a, 10 b for driving a mechanism disposed on the distal end side from the joint structure 1 are spanned. 11 is provided. The number of the circumferential grooves 11 varies depending on the number of mechanisms arranged on the tip side. In the example shown in FIG. 7, one wire 10a is stretched so as to meander alternately in one of the circumferential grooves 11 of the three

pulleys

71, 72, 73, and the other wire 10b is made of three wires. -The other circumferential grooves 11 of the

wires

71, 72, 73 are suspended so as to meander alternately in the opposite direction to the one wire 10a.

The operation of the joint structure 1 of the manipulator 100 according to this embodiment configured as described above will be described below.
According to the joint structure 1 according to the present embodiment, when the second member 3 is swung with respect to the first member 2, the first member 2 is moved from the first member 2 side by one of two operation wires (not shown). By pulling the two members 3, the second member 3 can be swung in two directions.

In this case, since the gear portion 62a of the second link member 62 that meshes with the first gear portion 21 provided in the first member 2 rolls around the first bending shaft 51, as shown in FIG. The position of the second bending shaft 52 moves around the first bending shaft 51, and the second link member 62 rotates around the second bending shaft 52. Accordingly, as shown in FIG. 9, the first link member 61 that is swingably attached to the first bending shaft 51 and the second bending shaft 52 swings around the first bending shaft 51. At the same time, the position of the third bending shaft 53 also moves around the second bending shaft 52 by the swing of the second link member 62 around the second bending shaft 52. 9, since the second gear portion 31 of the second member 3 is engaged with the gear portion 61a of the first link member 61, the second gear portion 31 is formed as shown in FIG. By rolling around the second bending shaft 52, the second member 3 is swung with respect to the second link member 62.

That is, the second member 3 has a swing angle of the first link member 61 with respect to the first member 2 and a swing angle of the second link member 62 with respect to the first link member 61 with respect to the first member 2. The second member 3 is swung by an angle obtained by adding up the swinging angle of the second member 3 with respect to the second link member 62.
As a result, even if the swing angle of each

link member

61, 62 is small, the second member 3 can be swung with respect to the first member 2 at a large swing angle. That is, the second member 3 is largely swung with respect to the first member 2 while suppressing the swing angle between the adjacent first member 2, the

link members

61, 62 or the second member 3 to avoid interference. There is an advantage that you can.

Further, according to the joint structure 1 according to the present embodiment, since the conditional expressions (1) and (2) are satisfied, the wires meandering around the

pulleys

71, 72, and 73 There is an advantage that the path lengths of 10a and 10b need not be changed regardless of the swing angle of the second member 3 with respect to the first member 2.

Here, conditions that do not require changing the path length of the

wires

10a and 10b regardless of the swing angle of the second member 3 with respect to the first member 2 will be described in detail.
As shown in FIG. 11 and FIG. 12, when n bent joints 4 are provided between the first member 2 and the second member 3, the swing angle θn of each link member 6 and the gears The relationship between the part (rolling part) 6a and the pitch circle radius Rkj (k = 1, 2, j = 1, 2,..., N) is as follows.

R11 × θ1 = R12 × θ2
R13 × θ3 = R14 × θ4
...
R1 (n−2) × θn−2 = R1 (n−1) × θn−1
R22 × θ2 = R23 × θ3
R24 × θ4 = R25 × θ5
...
R2 (n−1) × θn−1 = R2n × θn (3)

From the above formula (A),
θ2 / θ1 = (R11 / R12)
θ3 / θ1 = (R22 / R23) × (R11 / R12)
θ4 / θ1 = (R13 / R14) × (R22 / R23) × (R11 / R12)
...
θn / θ1 = (R2 (n−1) / R2n) ×... × (R11 / R12) (4)
It becomes.

As shown in FIG. 13, when the second member 3 swings in one direction with respect to the first member 2, the wires 10 that are meandered alternately around the pulley 7 are passed over the first member 2. On the other hand, the winding length is increased by r1 × θ1 in the first pulley 7 as compared to the state in which the second member 3 is not swinging, while r2 × in the next adjacent pulley 7. The relationship in which the winding length decreases by θ2 is successively continued. In FIG. 13, portions where the path length in the wire 10 increases, decreases, and changes are shown.
Here, ri (i = 1, 2,..., N) is a radius of the pulley 7 provided on the i-th bending shaft 5.

Therefore, the condition for not changing the path length of the wire 10 regardless of the swing is:
r1 × θ1−r2 × θ2 + r3 × θ3... + (− 1) ^{n + 1} r (n−1) × θn−1 = 0
(5)
It is.

By dividing the above equation (5) by θ1 and substituting equation (4),
r1-r2 × (R11 / R12) +
+ (− 1) ^{n + 1} r (n−1) × (R2 (n−1) / R2n) ×... × (R11 / R12) = 0
That is,

It becomes.

Substituting n = 3 in the present embodiment into Equation 1,
r1-r2 * R11 / R12 + r3 * R11 / R12 * R22 / R23 = 0
For example,
R11: R12: R22: R23 = 1: 1: 1: 1
r1: r2: r3 = 1: 2: 1
Or
R11: R12: R22: R23 = 2: 1: 1: 2
r1: r2: r3 = 1: 1: 1

That is, in the case of n = 3, when the conditional expression (1) and the conditional expression (2) are satisfied, the expression 1 is satisfied, and the second member 3 is swung with respect to the first member 2. However, it is not necessary to change the path length of the wire 10.

Further, according to the joint structure 1 according to the present embodiment, since the conditional expression (1) is satisfied, the position close to the first member 2 without turning the second member 3 relative to the first member 2. It can be swung so that it may be arranged.
For example, when the second member 3 is swung by 135 ° with respect to the first member 2, as shown in FIG. 9, θ1 = 33.75 °, θ2 = 67.5 °, θ3 = 33.75. The second member 3 can be swung closer to the first member 2 than when the angle θ1 to θ3 is swung evenly.

Here, conditions for swinging the second member 3 to a position close to the first member 2 will be described.
That is, as shown in FIG. 11, the plurality of arranged flexion joints 4 swing most greatly near the center of the array and swing smallest on both sides of the array, so that all the link members 6 are evenly distributed. The second member 3 can be swung to a position close to the first member 2 as compared with the case where the second member 3 is swung.

More generally, if the total of all swing angles is Φ,
θ1 + θ2 + ... + θn = Φ
f (m) = abs (Φ / 2− (θ1 + θ2 +... + θm)) (6)
Where m is the smallest integer,
θ1 ≦ θ2 ≦ θ3 ≦ ... ≦ θm
θn ≦ θn−1 ≦… ≦ θm + 1 (7)
In this case, the second member 3 can be swung so as to be closest to the first member 2.

Substituting equation (4) into equations (6) and (7),
If n is an even number,
R11 ≧ R12, R13 ≧ R14,..., R1 (m−1) ≧ R1m,
R1n ≧ R1 (n−1), R1 (n−2) ≧ R1 (n−3),..., R1 (m + 2) ≧ R1 (m + 1),
R23 ≧ R24,..., R2 (m−1) ≧ R2m,
R2 (n-2) ≧ R2 (n-3),..., R2 (m + 2) ≧ R2 (m + 1),
If n is odd,
R11 ≧ R12, R13 ≧ R14,..., R1 (m−1) ≧ R1m,
R1 (n−2) ≧ R1 (n−3),..., R1 (m + 2) ≧ R1 (m + 1),
R23 ≧ R24,..., R2 (m−1) ≧ R2m,
R2 (n) ≧ R2 (n−1),..., R2 (m + 2) ≧ R2 (m + 1) (8)
And m is an integer that minimizes the following function f (m).

In the case of n = 3 in the present embodiment, since m = 2 and the conditional expression (1) is satisfied, R11 ≧ R12 and R23 ≧ R22 are satisfied, and the conditional expression (8) is satisfied. The two members 3 can be swung so as to be closest to the first member 2.
For example, as shown in FIG. 14, in the case of the joint structure 1 having the five bent joint portions 4 satisfying the conditional expression (8), the second member 3 is swung by the same angle with respect to the first member 2. Compared with the reference example shown in FIG. 15, the distance between the first bending shaft 51 and the fifth bending shaft (shaft) 55 can be made sufficiently small, so that the second member 3 is replaced with the first member 2. It can be swung so as to be closest.

Next, a joint structure 12 according to a second embodiment of the present invention will be described below with reference to the drawings.
The joint structure 12 according to the present embodiment satisfies the following conditional expression instead of the conditional expression (1) in the joint structure 1 according to the first embodiment.

That is, the pitch circle radius Rkj (k = 1, 2, j = 1, 2,..., N) of each

gear portion

6a, 21, 31 is
If n is an even number,
R11 ≧ R13 ≧ R15 ≧ ... ≧ R1 (n−1),
R12 ≧ R14 ≧ R16 ≧ ... ≧ R1n,
R23≥R25≥R27≥ ... ≥R2 (n-1),
R22≥R24≥R26≥ ... ≥R2 (n-2),
If n is odd,
R11≥R13≥R15≥ ... ≥R1 (n-2),
R12≥R14≥R16≥ ... ≥R1 (n-1),
R23≥R25≥R27≥ ... ≥R2n,
R22≥R24≥R26≥ ... ≥R2 (n-1)
Meet the relationship.

Specifically, as shown in FIGS. 16 and 17, when n = 5,
R11 ≧ R13, R12 ≧ R14, R22 ≧ R24, R23 ≧ R25
It has become.
For example, in the example shown in FIGS.
R11 = 1.8 mm, R12 = 1.2 mm, R13 = 1.2 mm, R14 = 0.8 mm, R22 = 1 mm, R23 = 1.5 mm, R24 = 0.6 mm, R25 = 0.9 mm, the first The diameter of the second member 3 can be reduced with respect to the member 2. Thereby, it is suitable as a joint structure of the manipulator 100 to be inserted into details.

Also, in this case, by making the radius of all the pulleys 7 equal, Equation 1 is satisfied, and there is an advantage that it is not necessary to change the path length of the wire 10 regardless of the swing angle.

Here, conditions for reducing the diameter of the second member 3 relative to the first member 2 without changing the path length of the wire 10 regardless of the swing angle will be described.
In order to reduce the diameter, the pitch circle radii Rkj (k = 1, 2, j = 1, 2,..., N) of the

gear portions

6a, 21 and 31 are made closer to the second member 3 from the first member 2. Just make it smaller.

The condition for reducing the diameter when the change in the path length of the wire 10 during swinging is allowed is expressed by the following equation.
If n is an even number,
R11≥R12≥R13≥R14≥ ... ≥R1n (8)
R22≥R23≥R24≥ ... ≥R2 (n-1) (9)
If n is odd,
R11≥R12≥R13≥R14≥ ... ≥R1 (n-1) (10)
R22≥R23≥R24≥ ... ≥R2n (11)

Further, the condition that does not require changing the path length of the wire 10 at the time of swinging is expressed by the ratio of the pitch circle radii of the

gear portions

6a, 21, 31 that mesh with each other as shown in the equation (1).
That is, the relationship between the pitch circle radii of the

meshing gear portions

6a, 21 and 31 (for example, R11 and R12, R13 and R14) affects the change in the path length of the wire 10 during swinging. In consideration of the ease of design, it is desirable that conditional expression (8) to conditional expression (11) for reducing the diameter are not included.

Therefore, each of conditional expressions (8) to (11) is separated into two expressions as follows.
Thereby, it becomes possible to design freely the relationship of the pitch circle radius of each

gear part

6a, 21, 31 which meshes | engages.

That is, the pitch circle radius design for preventing the wire 10 from changing the path length during swinging and the pitch circle radius design for reducing the diameter can be separately implemented.
If n is an even number,
R11 ≧ R13 ≧ R15 ≧ ... ≧ R1 (n−1),
R12 ≧ R14 ≧ R16 ≧ ... ≧ R1n,
R23≥R25≥R27≥ ... ≥R2 (n-1),
R22≥R24≥R26≥ ... ≥R2 (n-2),
If n is odd,
R11≥R13≥R15≥ ... ≥R1 (n-2),
R12≥R14≥R16≥ ... ≥R1 (n-1),
R23≥R25≥R27≥ ... ≥R2n,
R22≥R24≥R26≥ ... ≥R2 (n-1)
Meet the relationship.

Moreover, in the said embodiment, although the gearwheel was illustrated as rolling

part

6a, 21, 31, 61a, 62a, it is not limited to this, The other rolling part which carries out rolling contact like a friction wheel is employ | adopted. May be.

DESCRIPTION OF

SYMBOLS

1,12 Joint structure 2 1st member 3 2nd member 4 Bending joint part 5 Bending axis (shaft)
6 Link member 6a Gear part (rolling part)
7 Pulley 21 1st gear part (1st rolling part)
31 Second gear part (second rolling part)
51 First bending axis (shaft)
52 Second bending axis (shaft)
53 Third bending axis (shaft)
55 Fifth bending axis (shaft)
61 First link member (link member)
61a, 62a Gear part (rolling part)
62 Second link member (link member)
71 First Puri (Puri)
72 Second Puri (Puri)
73 3rd Puri (Puri)

Claims

A first member provided with a first rolling part;
A second member provided with a second rolling part;
N to n-th mutually parallel shafts in order from the first member side constituting n (n ≧ 3) bent joints between the second member and the first member, and N-1 link members from the first to the (n-1) th in order from the side of the first member, which is arranged so as to be swingable between the shafts and provided with a rolling portion at at least one end;
A pulley that is rotatably supported on each of the shafts and spans a wire;
The first rolling portion is disposed so as to be in rolling contact with the rolling portion of the second link member,
The second rolling part is arranged to be in rolling contact with the rolling part of the (n-2) th link member;
A joint structure of a manipulator arranged so that the rolling portion of the m-th (1 ≦ m <n−3) link member is in rolling contact with the rolling portion of the m + 2 link member.
2. The joint structure of the manipulator according to claim 1, wherein the following conditional expression is satisfied.

here,
Rkj (k = 1, 2, j = 1, 2,..., N) is the k-th rolling part and the rolling parts of the group of link members that are in rolling contact with the k-th rolling part in sequence, A radius of the rolling portion disposed around the j-th shaft;
ri (i = 1, 2,..., n) is a radius of each of the pulleys provided on the i-th shaft.
The joint structure of the manipulator according to claim 1 or 2, wherein the following conditional expression is satisfied.
If n is an even number,
R11 ≧ R12, R13 ≧ R14,..., R1 (m−1) ≧ R1m,
R1n ≧ R1 (n−1), R1 (n−2) ≧ R1 (n−3),..., R1 (m + 2) ≧ R1 (m + 1),
R23 ≧ R24,..., R2 (m−1) ≧ R2m,
R2 (n-2) ≧ R2 (n-3),..., R2 (m + 2) ≧ R2 (m + 1),
If n is odd,
R11 ≧ R12, R13 ≧ R14,..., R1 (m−1) ≧ R1m,
R1 (n−2) ≧ R1 (n−3),..., R1 (m + 2) ≧ R1 (m + 1),
R23 ≧ R24,..., R2 (m−1) ≧ R2m,
R2 (n) ≧ R2 (n−1),..., R2 (m + 2) ≧ R2 (m + 1)
It is.
Here, Rkj (k = 1, 2, j = 1, 2,..., N) is the k-th rolling portion and the rolling portions of the group of the link members that are sequentially in rolling contact with the k-th rolling portion. The radius of the rolling portion arranged around the j-th shaft,
m is an integer that minimizes the following function f (m).
The joint structure of the manipulator according to any one of claims 1 to 3, wherein the following conditional expression is satisfied.
If n is an even number,
R11 ≧ R13 ≧ R15 ≧ ... ≧ R1 (n−1),
R12 ≧ R14 ≧ R16 ≧ ... ≧ R1n,
R23≥R25≥R27≥ ... ≥R2 (n-1),
R22≥R24≥R26≥ ... ≥R2 (n-2),
If n is odd,
R11≥R13≥R15≥ ... ≥R1 (n-2),
R12≥R14≥R16≥ ... ≥R1 (n-1),
R23≥R25≥R27≥ ... ≥R2n,
R22≥R24≥R26≥ ... ≥R2 (n-1)
It is.
Here, Rkj (k = 1, 2, j = 1, 2,..., N) is the k-th rolling portion and the rolling portions of the group of the link members that are sequentially in rolling contact with the k-th rolling portion. The radius of the rolling portion arranged around the j-th shaft.
The joint structure of the manipulator according to any one of claims 1 to 4, wherein the rolling portion is a gear portion, and Rkj is a pitch circle radius.
n = 3,
R11: R12: R22: R23 = 2: 1: 1: 2
And
r1 = r2 = r3
The joint structure of the manipulator according to claim 2, wherein