JP2019195864A - Joint mechanism and multiple-joint mechanism - Google Patents

Abstract

To provide a joint mechanism that can act to extend and contract, bend, and expand with high precision and also can be made compact.SOLUTION: A joint mechanism 30 comprises: joint ends 20, 21; a universal joint 304 which is arranged between them slidably along a center axis Z and rotatably around the center axis Z; coil springs 301a, 301b which are provided between the joint ends 20, 21 and the universal joint 304 respectively; and wires 201a-201c which are connected to the joint end 20 at three points in parallel with the center axis Z, and penetrate the joint end 21 at three points in parallel with the center axis Z.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a joint mechanism capable of expansion, contraction, and extension, and a multi-joint mechanism configured by connecting a plurality of the joint mechanisms.

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

  In addition, there is a conventional technique in which a plurality of joint mechanisms capable of bending and extending are accommodated inside a robot body in order to realize not only bending and extension but also expansion and contraction (see, for example, Patent Document 2). . This Patent Document 2 realizes the extension operation by pushing out the joint mechanism to the outside of the robot body as necessary.

  Further, as another means for realizing expansion / contraction of the joint mechanism, a technique for realizing expansion / contraction operation by separately providing a joint mechanism dedicated for expansion / contraction between joint mechanisms capable of bending and extending (see FIG. For example, see Patent Document 3).

JP-A-6-114785 JP 2016-133203 A JP 2014-188607 A

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

  In the joint mechanism of Patent Document 2, in addition to bending and extending, an expansion and contraction operation is also possible. However, since the joint mechanism is housed inside the robot body, the robot body is increased in size.

  The joint mechanism described in Patent Document 3 can also be expanded and contracted in addition to bending and extending. However, it is necessary to separately provide a joint mechanism dedicated for expansion and contraction between joint mechanisms capable of bending and extending. Therefore, the joint mechanism described in Patent Document 3 cannot perform necessary operations with high accuracy. Moreover, the whole joint mechanism will be enlarged.

  The present invention is intended to solve the above-described problems, and provides a joint mechanism and a multi-joint mechanism that can perform expansion / contraction, bending, and extension operations with high accuracy and can be miniaturized. Objective.

  The joint mechanism according to the present invention is slidable along the central axis connecting the first and second joint ends between the first and second joint ends and the first and second joint ends and is centered. A universal joint rotatably disposed around an axis; first and second elastic bodies provided between the first and second joint ends and the end of the universal joint; and a first joint end And a string-like member penetrating the second joint end at at least three points in parallel with the central axis.

  In the joint mechanism and the multi-joint mechanism according to the present invention, a universal joint that is slidable along the central axis and rotatable about the central axis is disposed between the first and second joint ends. An elastic body is provided between each of the two joint ends and the end of the universal joint, and a string-like member that contracts between the first and second joint ends is provided. As a result, the expansion, contraction, 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 a disassembled 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 at the time of shrinking the joint mechanism which concerns on Embodiment 1 of this invention. It is sectional drawing at the time of extending the joint mechanism which concerns on Embodiment 1 of this invention. It is sectional drawing at the time of bending the joint mechanism which concerns on Embodiment 1 of this invention. It is a disassembled perspective view of the joint mechanism which concerns on the modification of Embodiment 1 of this invention. It is sectional drawing at the time of contracting the joint mechanism which concerns on the modification of Embodiment 1 of this invention. It is a perspective view at the time of contracting the joint mechanism which concerns on the modification of Embodiment 1 of this invention. 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 a disassembled 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, an embodiment of a joint mechanism disclosed in the present application will be described in detail with reference to the accompanying drawings. However, the following embodiments are merely examples, and the present invention is not limited to these embodiments.

Embodiment 1 FIG.
FIG. 1 is a perspective view showing an overall configuration of a mobile robot 100 including a joint mechanism according to Embodiment 1 of the present invention.

  The mobile robot 100 is configured by connecting a plurality of joint mechanisms 30, 31, 32, 33, and 34 that can be expanded, contracted, and extended. 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, and 34 are formed.

  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 of the components of FIG. 2 in an assembled state. Hereinafter, the central axis Z is defined so as to penetrate the centers of the disk-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-like members are joined at the joint portion 304a, and the angle at which the two shaft-like 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 end portions of the universal joint 304 are accommodated, 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. The universal joint 304 is sandwiched between the coil spring 301a and the coil spring 301b. The joint 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.

  Note that 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 merely 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 a 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 stretched by the elastic force of the coil spring 303. Therefore, when the joint end 20 and the joint end 21 rotate relatively around the central axis Z, this rotational state is held by the elastic force of the coil spring 303. That is, the joint mechanism 30 is provided with rigidity resulting from the elastic force of the coil spring 303.

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

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

  In FIG. 1, the wires 201 a to 201 c 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 201 a to 201 c penetrate the guide member, the joint ends 21 to 25 are not pulled toward 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 is shortened.

  FIG. 4A is a cross-sectional view of the joint mechanism 30 when the wires 201a to 201c are wound inside the robot body 10 and the joint end 20 and the joint end 21 are contracted. 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 body 10 and extended between the joint end 20 and the joint end 21.

  In FIG. 4A, when the wires 201a to 201c are wound up in the robot body 10 by the same amount, the attachment points of the holding members 20a to 20c at the joint ends 20 are respectively attached to the robot body by the same magnitude of force. Pulled in 10 directions.

  Accordingly, the distance between the joint end 20 and the joint end 21 while the parallel relationship between the joint end 20 and the joint end 21 is maintained by the elastic force of the coil spring 303 between the joint end 20 and the joint end 21. Will shrink. At this time, since the coil springs 301 a and 301 b that receive both ends of the universal joint 304 are also compressed with the same force, the joint 304 a of the universal joint 304 continues to be positioned at an 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 stopper portions 20d and 21d formed at the joint ends 20 and 21, respectively. This state is a state where the distance between the joint end 20 and the joint end 21 is the shortest, that is, the joint mechanism 30 is the most contracted state.

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

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

  When the wires 201 a to 201 c 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 302 a and 302 b of the joint ends 20 and 21. This state is a state where the distance between the joint end 20 and the joint end 21 is the longest, that is, the joint mechanism 30 is the most extended state.

  Next, a case is considered in which the parallel relationship between the joint ends 20 and 21 is changed and the joint mechanism 30 is bent or extended by providing a difference in the amount of the three wires 201a to 201c wound up or pulled out.

  FIG. 5 shows that after winding the wires 201a to 201c in the robot body 10 by the same amount, both ends of the universal joint 304 are brought into contact with the stopper portions 20d and 21d of the joint ends 20 and 21, respectively, and then the wire 201b is further wound. It is sectional drawing of the joint mechanism 30 at the time of winding only.

  In FIG. 5, only the wire 201b is wound, whereby the universal joint 304 is bent at the joint 304a, and the relative angle between the joint end 20 and the joint end 21 that have been in a parallel state is changed. Thereby, the bending of the joint mechanism 30 is realized.

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

  As shown in FIG. 1, by connecting the same structure as the joint mechanism 30 in series, the joint mechanisms 31, 32, 33, and 34 can be expanded, contracted, and extended similarly to 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 that are connected to the joint end 21 and penetrate the joint end 22 are provided. Each wire passes through the joint ends 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.

  Similarly, in the joint mechanism 32, three wires different from the joint mechanisms 30 and 31, which are connected to the joint end 22 and penetrate the joint end 23, are provided. Each wire passes through 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 that are connected to the joint end 23 and penetrate the joint end 24, which are different from the joint mechanisms 30, 31, and 32, are provided. Each wire passes through 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 that are connected to the joint end 24 and penetrate the joint end 25 are provided, which are different from the joint mechanisms 30, 31, 32, and 33. The base 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 is contracted and the coil spring 303 of the portion is compressed, and the force directed toward the robot body 10 due to the elastic force of the coil spring 303 is the fundamental side. The joint mechanisms 31, 32, 33, and 34 are added.

  As a result, when the joint mechanism 30 is contracted, the joint mechanisms 31, 32, 33, and 34 are slightly contracted in conjunction with the joint mechanism 30, and the amount of contraction is larger as the joint mechanism is closer to the robot body 10. Therefore, when it is desired to equalize the amount of contraction of each joint mechanism, the amount of winding of the wire is preferably reduced as the joint mechanism is closer to the robot body 10.

  Alternatively, the joint ends may be connected by an elastic member such as a rubber tube, and a wire may be passed through 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 accompanied by a displacement in the rotational direction around the central axis Z when extending and contracting.

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

  For example, as shown in FIG. 3, coil springs 301 a and 301 b provided between the joint ends 20 and 21 and the universal joint 304 respectively apply forces to the universal joint 304 from both ends, so that the joint 304 a This is for positioning at an intermediate point of the joint mechanism 30.

  Therefore, the rigidity of the coil springs 301a and 301b only needs to overcome the friction coefficient 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 smaller than that of the coil spring 303.

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

  As described above, in the joint mechanism according to Embodiment 1 of the present invention, it is possible to slide along the central axis Z between the first and second joint ends and the first and second joint ends. A universal joint rotatably disposed around the central axis Z, first and second elastic bodies provided between the first and second joint ends and the end of the universal joint, respectively, A string-like member that is connected to the joint end at at least three points parallel to the central axis and penetrates the second joint end at at least three points parallel to the central axis.

  With such a configuration, the joint mechanism can be extended, bent, and extended with high accuracy and can be miniaturized. By connecting a plurality of such joint mechanisms, it is possible to reach a distance that could not be reached by a conventional multi-joint mechanism of the same size. In addition, since it is possible to move only the middle joint mechanism without changing the position of the joint mechanism at the front end, when a light source, a sensor, or the like is attached to the middle joint mechanism, the front end joint mechanism is affected. The position of the light source, sensor, etc. can be finely adjusted without any trouble.

  In addition, the robot main body 10 can be moved and an arbitrary object can be gripped by appropriately expanding, contracting, bending, and extending each joint mechanism sequentially.

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

  As shown in FIG. 7A, when the wires 201a to 201c are wound up and the distance between the joint end 20 and the joint end 21 is reduced, the helical spline shapes 304b, 302aa, and 302ba result in FIG. 7B. As shown, the joint end 20 and the joint end 21 contract while rotating relatively around the central axis Z.

  In the first embodiment, the wires 201a to 201c are used as members for realizing the extension, bending and extension of the joint ends 20 and 21, but, for example, a member that itself contracts like an artificial muscle. May be used.

Embodiment 2. FIG.
Next, the joint mechanism according to Embodiment 2 of the present invention will be described. In the following description, the same or similar components as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is 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. And the rotation state at the time of the joint end 20 and the joint end 21 rotating around the central axis Z was maintained by this rigidity.

  On the other hand, the second embodiment aims to reduce the number of components 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 an overall configuration of mobile robot 200 including the joint mechanism according to Embodiment 2 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, 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 therebetween. FIG. 10 is a cross-sectional view of the components shown in FIG. 9 assembled.

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

  Further, guide portions 2302a and 2302b for holding the universal joint 2304 are attached to the joint ends 20 and 21, respectively. Serrations 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 end portions of the universal joint 2304 are accommodated, respectively.

  The universal joint 2304 is 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 and 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 section, 302b, 2302b guide section, 303 coil spring (third elastic body), 304 universal joint, 201a wire, 201b wire, 201c wire.

Claims (8)

First and second joint ends;
A universal joint disposed between the first and second joint ends so as to be slidable along the central axis connecting the first and second joint ends and rotatable about the central axis;
First and second elastic bodies provided respectively between the first and second joint ends and the end of the universal joint;
A joint mechanism comprising: a string-like member connected to the first joint end at at least three points parallel to the central axis and penetrating the second joint end at at least three points parallel to the central axis .   The first and second joint ends are respectively provided with first and second guide portions that receive the first and second elastic bodies and receive the end portions of the universal joint, respectively. Item 2. The joint mechanism according to Item 1.   The joint mechanism according to claim 2, 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 3, 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 4, wherein the third elastic body is configured by a coil spring.   The joint mechanism according to any one of claims 2 to 5, wherein helical spline shapes are respectively formed on an outer peripheral surface of the universal joint and inner peripheral surfaces of the first and second guide portions.   The joint mechanism according to claim 2, wherein serration processing is performed on an outer peripheral surface of the universal joint and inner peripheral surfaces of the first and second guide portions. A multi-joint mechanism configured by connecting a plurality of joint mechanisms according to any one of claims 1 to 7,
The adjacent joint mechanisms share the first and second joint ends, and are multi-joint mechanisms.

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