JP7023174B2 - Joint mechanism and multi-joint mechanism - Google Patents

Description

The present invention relates to a joint mechanism capable of stretching, flexing and extending, and a multi-joint mechanism configured by connecting a plurality of the joint mechanisms.

In mobile robots and the like, a multi-joint mechanism that realizes flexion and extension movements by connecting a plurality of joint mechanisms is known (see, for example, Patent Document 1).

Further, there is a prior art technique in which a plurality of connected joint mechanisms capable of flexion and extension are housed inside a robot body in order to realize not only flexion and extension but also expansion and contraction movements (see, for example, Patent Document 2). .. In Patent Document 2, the extension operation is realized by pushing the joint mechanism to the outside of the robot body as needed.

Further, as another means for realizing the expansion and contraction of the joint mechanism, a technique for realizing the expansion and contraction operation by separately providing a joint mechanism dedicated to expansion and contraction between the joint mechanisms capable of flexion and extension is also known (). For example, see Patent Document 3).

Japanese Unexamined Patent Publication No. 6-114785 Japanese Unexamined Patent Publication No. 2016-132053 Japanese Unexamined Patent Publication No. 2014-188607

The joint mechanism described in Patent Document 1 can flex and extend, but cannot expand and contract. Therefore, there is a limit to the movement that can be performed as a mobile robot.

In the joint mechanism of Patent Document 2, in addition to flexion and extension, expansion and contraction movements are also possible. However, since the joint mechanism is housed inside the robot body, the size of the robot body becomes large.

The joint mechanism described in Patent Document 3 can also expand and contract in addition to flexion and extension. However, it is necessary to separately provide a joint mechanism dedicated to expansion and contraction between the joint mechanisms capable of flexion and extension. Therefore, the joint mechanism described in Patent Document 3 cannot perform the required operation with high accuracy. In addition, the entire joint mechanism becomes large.

The present invention is intended to solve the above-mentioned problems, and to provide a joint mechanism and an articulated mechanism capable of performing expansion / contraction, flexion and extension movements with high accuracy and miniaturization. The purpose.

The joint mechanism according to the present invention is slidable and central along a central axis connecting the first and second joint ends between the first and second joint ends and the first and second joint ends. A universal joint rotatably arranged around the axis, a first and second elastic body provided between the first and second joint ends and the end of the universal joint, respectively, and a first joint end. It is provided with a string-like member that is connected to at least three points parallel to the central axis and penetrates the second joint end parallel to the central axis at at least three points, and the first and second joint ends are provided with. First and second guide portions are provided to accommodate the first and second elastic bodies and to receive the ends of the universal joints, respectively, and the outer peripheral surface of the universal joint and the first and second guide portions are provided. A helical spline shape is formed on the inner peripheral surface .

In the joint mechanism and the multi-joint mechanism according to the present invention, a universal joint slidable along the central axis and rotatable around the central axis is arranged between the first and second joint ends, and the first and second joint mechanisms are arranged. An elastic body is provided between the end of the two joints and the end of the universal joint, and a string-shaped member that contracts between the first and second joint ends is provided. As a result, the expansion / contraction, bending, and extension operations can be performed with high accuracy, and the size can be reduced.

It is a perspective view which shows the whole structure of the mobile robot provided with the joint mechanism which concerns on Embodiment 1 of this invention. It is an exploded perspective view of the joint mechanism which concerns on Embodiment 1 of this invention. It is sectional drawing of the joint mechanism which concerns on Embodiment 1 of this invention. It is sectional drawing when the joint mechanism which concerns on Embodiment 1 of this invention is contracted. It is sectional drawing when the joint mechanism which concerns on Embodiment 1 of this invention is extended. It is sectional drawing when the joint mechanism which concerns on Embodiment 1 of this invention is bent. It is an exploded perspective view of the joint mechanism which concerns on the modification of Embodiment 1 of this invention. It is sectional drawing when the joint mechanism which concerns on the modification of Embodiment 1 of this invention is contracted. It is a perspective view when the joint mechanism which concerns on the modification of Embodiment 1 of this invention is contracted. It is a perspective view which shows the whole structure of the mobile robot provided with the joint mechanism which concerns on Embodiment 2 of this invention. It is an exploded perspective view of the joint mechanism which concerns on Embodiment 2 of this invention. It is sectional drawing of the joint mechanism which concerns on Embodiment 2 of this invention.

Hereinafter, embodiments of the joint mechanism disclosed in the present application will be described in detail with reference to the accompanying drawings. However, the embodiments shown below are examples, and the present invention is not limited to these embodiments.

Embodiment 1.
FIG. 1 is a perspective view showing the overall configuration of the mobile robot 100 provided with the joint mechanism according to the first embodiment of the present invention.

The mobile robot 100 is configured by connecting a plurality of joint mechanisms 30, 31, 32, 33, 34 capable of expansion / contraction, flexion, and extension. Specifically, the mobile robot 100 includes a robot body 10 and a plurality of disc-shaped joint ends 20, 21, 22, 23, 24, 25, and a plurality of joint mechanisms 30 between the joint ends. , 31, 32, 33, 34, respectively.

FIG. 2 is an exploded perspective view of one joint mechanism 30 formed between the joint ends 20 and 21. FIG. 3 is a cross-sectional view in a state where each component of FIG. 2 is assembled. From this point onward, the central axis Z is defined so as to penetrate the centers of the disc-shaped joint ends 20 and 21.

The joint mechanism 30 includes a universal joint 304. The universal joint 304 has a well-known structure in which two shaft-shaped members are joined at the joint portion 304a, and the angle at which the two shaft-shaped members are joined can be freely changed.

Guide portions 302a and 302b for holding the universal joint 304 are attached to the joint ends 20 and 21, respectively. Inside the guide portions 302a and 302b, coil springs 301a and 301b for receiving the end portions of the universal joint 304 are housed, respectively.

Both ends of the universal joint 304 are inserted into the guide portions 302a and 302b of the joint ends 20 and 21, respectively, and the universal joint 304 is sandwiched between the coil spring 301a and the coil spring 301b. The joint portion 304a of the universal joint 304 is held at an intermediate position between the joint end 20 and the joint end 21 by the elastic force of the coil springs 301a and 301b.

Both ends of the universal joint 304 are not joined to the guide portions 302a and 302b of the joint ends 20 and 21, but are only inserted. Therefore, the universal joint 304 can slide along the central axis Z with respect to the joint ends 20 and 21, and can freely rotate 360 degrees around the central axis Z.

Further, the joint mechanism 30 includes a coil spring 303 that surrounds the universal joint 304 in parallel with the central axis Z. Guide portions 20e and 21e for holding the coil spring 303 are formed at the joint ends 20 and 21, respectively. Both ends of the coil spring 303 are inserted into the guide portions 20e and 21e of the joint ends 20 and 21, respectively.

The joint end 20 and the joint end 21 are in a state of being stretched by the elastic force of the coil spring 303. Therefore, when the joint end 20 and the joint end 21 rotate relative to each other around the central axis Z, this rotational state is maintained by the elastic force of the coil spring 303. That is, the joint mechanism 30 is provided with rigidity due to the elastic force of the coil spring 303.

Further, the joint mechanism 30 includes wires 201a to 201c parallel to the central axis Z. Holding members 20a to 20c are attached to the joint ends 20, and the tips of the wires 201a to 201c are fixed to the joint ends 20 by the holding members 20a to 20c. That is, the wires 201a to 201c are connected to the joint end 20 in parallel with the central axis Z.

On the other hand, guide members 21a to 21c are attached to the joint ends 21. Through holes are formed in the guide members 21a to 21c, and the wires 201a to 201c penetrate the through holes. That is, the wires 201a to 201c penetrate the joint end 21 in parallel with the central axis Z.

In FIG. 1, the wires 201a to 201c penetrate the joint ends 22, 23, 24, and 25 in parallel with the central axis Z, and their roots are connected to a motor (not shown) inside the robot body 10. .. When the wires 201a to 201c are wound by the motor, the joint end 20 to which the tips of the wires 201a to 201c are connected is pulled in the direction of the robot body 10.

At this time, at the joint ends 21 to 25, since the wires 201a to 201c penetrate the guide member, the joint ends 21 to 25 are not pulled in the direction of the robot body 10. That is, the relative position between the robot body 10 and the joint ends 21 to 25 does not change, and the distance between the joint end 20 and the joint end 21 becomes short.

FIG. 4A is a cross-sectional view of the joint mechanism 30 when the wires 201a to 201c are wound inside the robot main body 10 and the space between the joint ends 20 and the joint ends 21 is contracted. Further, FIG. 4B is a cross-sectional view of the joint mechanism 30 when the wires 201a to 201c are pulled out from the inside of the robot main body 10 and extended between the joint ends 20 and the joint ends 21.

In FIG. 4A, when the wires 201a to 201c are wound around the inside of the robot body 10 by the same amount, the attachment points of the holding members 20a to 20c of the joint end 20 are attached to the robot body by the same magnitude of force. It is pulled in the direction of 10.

As a result, the elastic force of the coil spring 303 between the joint end 20 and the joint end 21 keeps the parallel relationship between the joint end 20 and the joint end 21 maintained, and the distance between the joint end 20 and the joint end 21 is maintained. Shrinks. At this time, since the coil springs 301a and 301b that receive both ends of the universal joint 304 are also compressed with the same force, the joint portion 304a of the universal joint 304 continues to be located at the intermediate point between the joint end 20 and the joint end 21.

When the wires 201a to 201c are further wound, both ends of the universal joint 304 come into contact with the stopper portions 20d and 21d formed at the joint ends 20 and 21, respectively. In this state, the distance between the joint end 20 and the joint end 21 is the shortest, that is, the joint mechanism 30 is the shortest.

On the other hand, in FIG. 4B, when the wires 201a to 201c are pulled out from the inside of the robot body 10 by the same amount, the attachment points of the holding members 20a to 20c of the joint end 20 are caused by the elastic force of the coil springs 301a and 301b. It is pushed out in the opposite direction to the robot body 10 by the force of the same magnitude.

As a result, the distance between the joint end 20 and the joint end 21 is increased while maintaining the parallel relationship between the joint end 20 and the joint end 21. At this time, the joint portion 304a of the universal joint 304 continues to be located at the intermediate point between the joint end 20 and the joint end 21 due to the equal elastic force of the coil springs 301a and 301b that receive both ends of the universal joint 304.

When the wires 201a to 201c are further pulled out, both ends of the universal joint 304 are pulled out to the maximum positions that can be held by the guide portions 302a and 302b of the joint ends 20 and 21. This state is the state in which the distance between the joint end 20 and the joint end 21 is the most extended, that is, the state in which the joint mechanism 30 is the most extended.

Next, consider a case where the parallel relationship between the joint ends 20 and 21 is changed and the joint mechanism 30 is flexed or extended by providing a difference in the winding amount or the drawing amount of the three wires 201a to 201c.

In FIG. 5, the wires 201a to 201c are wound inside the robot body 10 by the same amount, and both ends of the universal joint 304 are brought into contact with the stoppers 20d and 21d of the joint ends 20 and 21, respectively, and then the wires 201b are further drawn. It is sectional drawing of the joint mechanism 30 when only the wire is taken up.

In FIG. 5, by winding only the wire 201b, the universal joint 304 is bent at the joint portion 304a, and the relative angle between the joint end 20 and the joint end 21 which had been in a parallel state until then changes. As a result, the flexion of the joint mechanism 30 is realized.

Further, when the joint mechanism 30 is bent, the coil spring 303 is bent. Therefore, when the wire 201b is pulled out again and the winding amounts of the three wires 201a to 201c are returned to the same state, the bending of the coil spring 303 is eliminated and the bending of the joint portion 304a of the universal joint 304 is also restored. As a result, the joint end 20 and the joint end 21 are brought into a parallel state again, and the extension of the joint mechanism 30 is realized.

As shown in FIG. 1, by connecting the same structures as the joint mechanism 30 in series, the joint mechanisms 31, 32, 33, and 34 also realize expansion and contraction, flexion, and extension as in the joint mechanism 30. can do.

Specifically, in the joint mechanism 31, three wires different from the wires 201a to 201c of the joint mechanism 30 are provided, which are connected to the joint end 21 and penetrate the joint end 22. Each wire penetrates the joint ends 23, 24, 25 in parallel with the central axis Z, and their roots are connected to a motor (not shown) inside the robot body 10.

Similarly, in the joint mechanism 32, three wires different from the joint mechanisms 30 and 31 are provided, which are connected to the joint end 22 and penetrate the joint end 23. Each wire penetrates the joint ends 24 and 25 in parallel with the central axis Z, and their roots are connected to a motor (not shown) inside the robot body 10.

Similarly, in the joint mechanism 33, three wires different from the joint mechanisms 30, 31, and 32 are provided, which are connected to the joint end 23 and penetrate the joint end 24. Each wire penetrates the joint end 25 in parallel with the central axis Z, and their roots are connected to a motor (not shown) inside the robot body 10.

Similarly, in the joint mechanism 34, three wires different from the joint mechanisms 30, 31, 32, and 33 are provided, which are connected to the joint end 24 and penetrate the joint end 25. The root of each wire is connected to a motor (not shown) inside the robot body 10.

For example, when the wire of the joint mechanism 30 at the tip is wound, the joint mechanism 30 contracts and the coil spring 303 at that portion is compressed, and the force toward the robot body 10 due to the elastic force of the coil spring 303 is on the root side. Joins the joint mechanisms 31, 32, 33, 34 of.

As a result, when the joint mechanism 30 is contracted, the joint mechanisms 31, 32, 33, and 34 also contract slightly in conjunction with the contraction, and the amount of contraction increases as the joint mechanism is closer to the robot body 10. Therefore, if it is desired to make the amount of contraction of each joint mechanism equal, it is preferable that the closer the joint mechanism is to the robot body 10, the smaller the amount of wire winding.

Alternatively, the joint ends may be connected by an elastic member such as a rubber tube, and a wire may be passed through the inside of the rubber tube. With this configuration, when the joint mechanism is contracted, the reaction force of the rubber tube is received, so that the influence on other joint mechanisms can be reduced.

Further, in the first embodiment, the coil spring 303 provided in the joint mechanism 30 in parallel with the central axis Z is not a little accompanied by a displacement in the rotational direction around the central axis Z when expanding and contracting.

Therefore, it is advisable to alternately change the winding direction of the coil spring in each joint mechanism. That is, it is preferable that the winding direction of the coil springs of the joint mechanisms 30, 32, and 34 is different from the winding direction of the coil springs of the joint mechanisms 31, 33.

Further, for example, as shown in FIG. 3, the coil springs 301a and 301b provided between the joint ends 20 and 21 and the universal joint 304, respectively, have their joint portions 304a formed by applying a force to the universal joint 304 from both ends. It is intended to be located at an intermediate point of the joint mechanism 30.

Therefore, it is sufficient that the rigidity of the coil springs 301a and 301b can overcome the coefficient of friction between the universal joint 304 and the guide portions 302a and 302b. Therefore, the rigidity of the coil springs 301a and 301b can be designed to be smaller than the rigidity of the coil spring 303.

By reducing the rigidity of the coil springs 301a and 301b, it is possible to reduce the torque required for the motor of the robot body 10 to wind up the wires 201a to 201c when the joint mechanism 30 is contracted and bent. As a result, the robot body 10 can be expected to be downsized.

As described above, in the joint mechanism according to the first embodiment of the present invention, it is slidable along the central axis Z between the first and second joint ends and the first and second joint ends. A universal joint rotatably arranged around the central axis Z, a first and second elastic body provided between the first and second joint ends and the end of the universal joint, respectively, and a first. It is connected to the joint end in parallel with the central axis at at least three points, and is provided with a string-like member penetrating the second joint end in parallel with the central axis at at least three points.

With such a configuration, it is possible to obtain a joint mechanism capable of performing extension, flexion and extension with high accuracy and being miniaturized. By connecting a plurality of such joint mechanisms, it becomes possible to reach a distance that cannot be reached by a conventional multi-joint mechanism having the same size. In addition, since it is possible to move only the joint mechanism in the middle without changing the position of the joint mechanism at the tip, when a light source, a sensor, etc. are attached to the joint mechanism in the middle, the joint mechanism at the tip is affected. It is possible to make fine adjustments to the positions of the light source, the sensor, and the like without the need for it.

Further, by appropriately expanding and contracting, bending and extending each joint mechanism in sequence, it becomes possible to move the robot body 10 and to grip an arbitrary object.

As a modification of the first embodiment, as shown in FIG. 6, helical spline shapes 304b and 302aa and 302ba are provided on the outer peripheral surface of the universal joint 304 and the inner peripheral surfaces of the guide portions 302a and 302b, respectively. It may be formed.

As shown in FIG. 7A, when the wires 201a to 201c are wound and controlled so as to reduce the distance between the joint end 20 and the joint end 21, the helical spline shapes 304b and 302aa and 302ba are shown in FIG. 7B. As shown, the joint end 20 and the joint end 21 contract while rotating relative to the central axis Z.

Further, in the first embodiment, the wires 201a to 201c are used as the members for realizing the extension, flexion and extension of the joint ends 20 and 21, but the members themselves contract, for example, artificial muscles. May be used.

Embodiment 2.
Next, the joint mechanism according to the second embodiment of the present invention will be described. In the following description, the same or similar components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the first embodiment, the joint mechanism 30 is provided with rigidity by providing the coil spring 303 between the joint ends 20 and 21. Then, due to this rigidity, the rotational state when the joint end 20 and the joint end 21 rotate around the central axis Z is maintained.

On the other hand, in the second embodiment, it is an object to reduce the number of parts by providing rigidity to the joint mechanism 30 without providing a coil spring between the joint ends 20 and 21.

FIG. 8 is a perspective view showing the overall configuration of the mobile robot 200 provided with the joint mechanism according to the second embodiment of the present invention.

The mobile robot 200 includes a robot body 10 and a plurality of disc-shaped joint ends 20, 21, 22, 23, 24, 25, and a plurality of joint mechanisms 230, 231 and 232 between the joint ends. 233 and 234 are formed, respectively.

FIG. 9 is an exploded perspective view of the joint ends 20 and 21 and the joint mechanism 230 formed between them. Further, FIG. 10 is a cross-sectional view in a state where each component of FIG. 9 is assembled.

The joint mechanism 230 includes a universal joint 2304. Serration processing 2304c is applied to the outer peripheral surface of the universal joint 2304.

Further, guide portions 2302a and 2302b for holding the universal joint 2304 are attached to the joint ends 20 and 21, respectively. Serration processing 2302ac and 2302bc are also applied to the inner peripheral surfaces of the guide portions 2302a and 2302b.

Inside the guide portions 2302a and 2302b, coil springs 2301a and 2301b for receiving the end portions of the universal joint 2304 are housed, respectively.

The universal joint 2304 can be rotated around the central axis Z by the serration processing 2304c applied to the outer peripheral surface of the universal joint 2304 and the serration processing 2302ac / 2302bc applied to the inner peripheral surface of the guide portions 2302a and 2302b. Be regulated. With such a configuration, the rigidity of the joint mechanism 230 can be ensured without providing the coil spring 303 between the joint ends 20 and 21 as in the first embodiment.

20 joint end, 21 joint end, 30,230 joint mechanism, 301a, 2301a coil spring (first elastic body), 301b, 2301b coil spring (second elastic body), 302a, 2302a guide part, 302b, 2302b guide part, 303 coil spring (third elastic body), 304 universal joint, 201a wire, 201b wire, 201c wire.

Claims (6)

The first and second joint ends and
A universal joint that is slidably and rotatably arranged around a central axis connecting the first and second joint ends between the first and second joint ends.
The first and second elastic bodies provided between the ends of the first and second joints and the ends of the universal joints, respectively.
It is provided with a string-like member connected to the first joint end in parallel with the central axis at at least three points and penetrating the second joint end in parallel with the central axis at at least three points .
The first and second joint ends are provided with first and second guide portions, respectively, for accommodating the first and second elastic bodies and receiving the ends of the universal joints, respectively.
A joint mechanism in which a helical spline shape is formed on the outer peripheral surface of the universal joint and the inner peripheral surface of the first and second guide portions, respectively . The joint mechanism according to claim 1 , wherein a third elastic body is provided between the first and second joint ends in parallel with the central axis. The joint mechanism according to claim 2 , wherein the rigidity of the third elastic body is larger than the rigidity of the first and second elastic bodies. The joint mechanism according to claim 3 , wherein the third elastic body is composed of a coil spring. A multi-joint mechanism configured by connecting a plurality of joint mechanisms according to any one of claims 1 to 4 .
An articulated mechanism in which adjacent joint mechanisms share the first and second joint ends. The first and second joint ends and
A universal joint that is slidably arranged along a central axis connecting the first and second joint ends and is rotatably arranged around the central axis between the first and second joint ends.
The first and second elastic bodies provided between the ends of the first and second joints and the ends of the universal joints, respectively.
With a string-like member fixed to the first joint end in parallel with the central axis at at least three points and penetrating the second joint end in parallel with the central axis at at least three points.
It is a multi-joint mechanism composed by connecting a plurality of joint mechanisms including.
An articulated mechanism in which adjacent joint mechanisms share the first and second joint ends.

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