Transformation mechanism and prosthetic arm using the same

Abstract

To provide a low-cost, simple deformation mechanism and a prosthetic hand using the same. [Solution] The deformation mechanism comprises an elastically deformable support portion extending from a base end, a plurality of links connected in series, adjacent links being rotatably connected around a rotation axis intersecting the direction of the link arrangement, and an articulated portion arranged along the support portion, a holding portion that holds the articulated portion relative to the support portion, and an actuator that changes the length of the articulated portion from the base end in the extending direction.

Description

Technical Field

[0001] The present invention relates to a deformation mechanism and a prosthetic hand using the same.

Background Art

[0002] For those with a congenital or acquired defect or hypoplasia in the palm due to congenital reasons or accidents, etc., a prosthetic hand equipped with a hand tip device that restores the shape and function of the hand is worn.

[0003] For example, in Patent Document 1, a finger drive unit of an electric prosthetic hand is disclosed, which includes a piston that moves forward and backward by a feed screw that rotates through a reduction gear by the rotation of a motor, a middle joint member that is connected to a base joint member that rotates in response to the movement of the piston, and a distal joint member that is connected to the middle joint member. When the base joint member rotates, the first sliding contact portion of the base joint member can bend a first wire provided between the middle joint member and the main body into a U shape.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The prosthetic hand of Patent Document 1 has a relatively large structure and can be used, for example, as a prosthetic hand for adults. In contrast, the size of an infant's finger is thinner and shorter than that of an adult's finger, and the shape is also very diverse. Therefore, a prosthetic hand for infants is likely to be a custom-made product, and it is difficult to use a prosthetic hand for adults such as that in Patent Document 1. Furthermore, there is also a situation where the cost involved in manufacturing the prosthetic hand is restricted in order to suppress the burden on caregivers and the like.

[0006] Therefore, there is a need for a mechanism that can perform flexion and extension movements while keeping costs down, for example, by sizing it to match the size of an infant's hand, and ensuring mechanical strength. In particular, since infants grow rapidly, the mechanism needs to be updated as they grow, but there is also a demand to reduce costs by reusing existing elements.

[0007] This invention has been made in view of the problems of the prior art, and aims to provide a deformation mechanism that is low-cost and has a simple structure, and a prosthetic hand using the same. [Means for solving the problem]

[0008] To achieve the above objective, one representative conversion mechanism of the present invention is: An elastically deformable support portion extending from the base end, It has multiple sprockets connected in series, adjacent sprockets are rotatably connected around a rotation axis that intersects the direction in which the sprockets are arranged, and a connecting section is arranged along the support section, A holding part that holds the connecting part relative to the support part, This is achieved by having an actuator that changes the length of the connecting portion from the base end in the extending direction. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a deformation mechanism that is low-cost and has a simple structure, and a prosthetic hand using the same. Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram showing an exploded view of the deformation mechanism according to the first embodiment. [Figure 2] Figure 2 is a side view of the deformation mechanism of the first embodiment, shown in its assembled state. [Figure 3]Figure 3 is a schematic diagram showing an exploded view of the deformation mechanism according to the second embodiment. [Figure 4] Figure 4 is a side view of the deformation mechanism of the second embodiment, shown in its assembled state. [Modes for carrying out the invention]

[0011] A roller chain, used for power transmission in machinery and other devices, consists of multiple joint elements (links) rotatably linked together. Each joint element has a degree of freedom of movement only in the rotational direction, while maintaining strong rigidity in other directions. Therefore, the operation of a roller chain can be said to be similar to, for example, the flexion movement of a prosthetic finger.

[0012] On the other hand, roller chains are inherently designed for power transmission and therefore have sufficient durability against rotational motion. While they are strong against tensile loads, they are weak against compressive loads, and are generally considered unsuitable for applications where roller chains are used as support members.

[0013] In response to this, the inventors, through diligent research, have realized a deformation mechanism that ensures rigidity in the compression direction while simultaneously enabling bending in the rotational direction by combining a roller chain with other components. Specifically, since the roller chain has a structure in which many joint elements are arranged in series, by attaching a spring material to the back side of the roller chain and integrating it with a periosteal member, it is possible to construct multiple joints that bend in one direction but have high rigidity in the other direction, making it possible to construct a deformation mechanism that mimics a finger skeleton of any length having any number of joints (generally 3 joints). The spring material can support the movement of the finger in the extension direction. The deformation mechanism of the present invention will be described below with reference to the drawings, but in the following embodiment, a specific part of the roller chain becomes a finger joint.

[0014] (First Embodiment) FIG. 1 is a schematic diagram showing the deformation mechanism 10 according to the first embodiment in an exploded view. FIG. 2 is a side view of the deformation mechanism 10 shown in an assembled state, where (a) shows the upright state and (b) shows the bent state. In FIG. 2(a), an artificial skin 30 used by covering the deformation mechanism 10 is shown by a dotted line, but is omitted in FIG. 2(b).

[0015] In FIG. 1, the deformation mechanism 10 includes an elastically deformable elongated leaf spring 11, a periosteal member 12, a tendon sheath member 13, a roller chain 14, and an axial actuator 15.

[0016] The leaf spring 11, which is a support part, can be bent in the left - right direction in FIG. 1, but has high rigidity in the direction perpendicular to the paper surface. The lower end of the leaf spring 11 is fixed to a base end part (not shown). When the deformation mechanism 10 is used as an artificial finger of a prosthetic hand, the base end part serves as a base attached to the back of the hand of the wearer who wears the prosthetic hand, for example.

[0017] The roller chain 14, which is a link part, includes a plurality of oval - plate - shaped sprockets 14a and a plurality of pins 14b. Pins 14b are implanted at both ends of the sprocket 14a, and adjacent sprockets 14a are connected in series to be rotatable with respect to each other via the pins 14b. Its rotation axis extends parallel to the direction (direction perpendicular to the paper surface) that intersects the arrangement direction of the sprockets 14a (vertical direction in the figure).

[0018] The roller chain 14 is arranged in FIG. 1 so as to go from below to above, be folded back, and then go downward again. The side of the roller chain 14 closer to the leaf spring 14 is defined as the first chain part (first part)​​​The tendon sheath member 13 has a flexible cylindrical shape formed of, for example, a silicon tube or a rubber tube. Here, it is assumed to be made of a transparent material, but it may be colored. The tendon sheath member 13 has cutouts 13a at predetermined intervals on the side away from the leaf spring 11 (the right side in FIG. 1). In the present embodiment, the tendon sheath member 13 and the periosteum member 12 constitute a holding portion. Further, the periosteum member 12 constitutes a fixing portion for fixing a part of the roller chain 14 to the leaf spring 11, and the tendon sheath member 13 integrally wraps the leaf spring 11 and the roller chain 14 and constitutes a cylindrical portion in which a plurality of cutouts 13a are formed at a plurality of locations of the portion facing the second chain portion 14B.

[0020] As shown in FIG. 2(a), the leaf spring 11 is disposed on the side (left side) of the tendon sheath member 13 where there is no cutout 13a, the roller chain 14 is disposed on the side where there is the cutout 13a, and the leaf spring 11 is disposed between the periosteum member 12 and the roller chain 14. Each component is disposed so as to abut against the inner circumference of the tendon sheath member 13, and there is substantially no gap. The periosteum member 12 is, for example, a gel-like member and functions so as to closely adhere to the leaf spring 11 and the first chain portion 14A facing the same, but it is not necessarily required to be provided.

[0021] When the axial actuator 15 is in a non-operating state, since no driving force is transmitted to the roller chain 14, the leaf spring 11 is in a free state where no external force is applied, and thus it is in an upright state as shown in FIG. 2(a). Also, along with the leaf spring 11, the tendon sheath member 13 is caused to be in an upright state, and the periosteum member 12 and the roller chain 14 held by the tendon sheath member 13 are also in an upright state. FIG. 2(a) corresponds to a state where the prosthetic finger is extended.

[0022] In contrast, when the axial actuator 15 operates and exerts a driving force to pull the lower end 14c of the second chain portion 14B downward, a portion of the second chain portion 14B moves downward within the tendon sheath member 13, but the first chain portion 14A does not move. As a result, the length of the leaf spring 11 of the second chain portion 14B corresponding to the first chain portion 14A along the direction of extension within the tendon sheath member 13 becomes shorter. In other words, by operating the axial actuator 15, the length of the roller chain 14 from the base end in the extension direction (vertical direction) can be changed.

[0023] However, since the second chain section 14B and the first chain section 14A remain held within the tendon sheath member 13, when the second chain section 14B is pulled downward, the adjacent links 14a rotate relative to each other, and as shown in Figure 2(b), the second chain section 14B bends together with the first chain section 14A as if bowing, with its tip 14C pointing downward. At this time, since the tendon sheath member 13 is provided with a notch 13a, it does not hinder the bending of the roller chain 14.

[0024] When the first chain portion 14A bends, the periosteal member 12 and the leaf spring 11 also bend in the same direction, and the leaf spring 11 undergoes elastic deformation due to the bending.

[0025] Subsequently, when the driving force of the axial actuator 15 is lost, the elastic force of the leaf spring 11 causes the second chain section 14B to return to its original position, thereby causing the periosteal member 12 and the roller chain 14 to become upright, returning to the state shown in Figure 2(a).

[0026] According to this embodiment, by combining the inexpensive yet relatively compact roller chain 14 with a leaf spring 11, etc., a deformation mechanism capable of both upright and flexible movement can be realized, making it suitable for use, for example, as a prosthetic finger for infants. Furthermore, even when the infant grows, the prosthetic can be adapted simply by changing the artificial skin 30, leaf spring 11, and periosteal member 12, and the running costs of the prosthetic hand can be reduced by reusing the roller chain 14 and axial actuator 15.

[0027] (Second Embodiment) Figure 3 is a schematic diagram showing the deformation mechanism 20 according to the second embodiment in an exploded state. Figure 4 is a side view of the deformation mechanism 20 in its assembled state, with (a) showing it in an upright state and (b) showing it in a bent state. In Figure 4(a), the artificial skin 30 used to cover the deformation mechanism 20 is shown by a dotted line, but it is omitted in Figure 4(b).

[0028] In Figure 3, the deformation mechanism 20 includes an elastically deformable elongated leaf spring 11, a periosteal member 12, a tendon sheath member 13, a cam mechanism 16, a roller chain 14, and a rotational actuator 17.

[0029] The leaf spring 11, periosteal member 12, tendon sheath member 13, and roller chain 14 are the same as in the first embodiment, so redundant explanations are omitted. However, the lower end of the roller chain 14 is fixed together with the leaf spring 11 to a base end (not shown).

[0030] The cam mechanism 16 has a flexible shaft 16a connected to a rotational actuator 17, and a plurality of cams 16b formed on the shaft 16a at predetermined intervals. The shaft 16a is arranged longitudinally between the first chain section 14A and the second chain section 14B. Each cam 16b protrudes in one direction relative to the shaft 16a, and the direction of protrusion changes according to the rotational position of the shaft 16a. For example, in Figure 3, the cam 16b protrudes to the right.

[0031] When the rotational actuator 17 is inactive, the cam 16b of the cam mechanism 16 is oriented in a direction along the space between the first chain portion 14A and the second chain portion 14B (perpendicular to the plane of the paper). As a result, the lengths of the first chain portion 14A and the second chain portion 14B become equal within the tendon sheath member 13, and the deformation mechanism 20 becomes upright as shown in Figure 4(a). Figure 4(a) corresponds to the state in which the prosthetic finger is extended.

[0032] In contrast, when the rotational actuator 17 operates, the shaft 16a of the cam mechanism 16 rotates, pushing the corresponding link 14a of the second chain section 14B away from the first chain section 14A. As a result, within the tendon sheath member 13, the length of the leaf spring 11 of the second chain section 14B along the direction in which it extends becomes shorter relative to the first chain section 14A.

[0033] However, since the second chain section 14B and the first chain section 14A remain held within the tendon sheath member 13, as shown in Figure 4(b), the shortening of the second chain section 14B causes the adjacent links 14a to rotate relative to each other, bending together with the first chain section 14A in a bowing motion. At this time, the notch 13a is provided in the tendon sheath member 13, so it does not hinder the bending of the roller chain 14. Preferably, the notch 13a is formed to correspond to the link 14a pushed out by the cam 16b.

[0034] Subsequently, when the rotational actuator 17 rotates the shaft 16a back to its original position, the elastic force of the leaf spring 11 causes the periosteal member 12 and the roller chain 14 to stand upright, and the link 14a, which was pushed out by the cam 16b, returns to its original position, returning to the state shown in Figure 4(a).

[0035] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail for the purpose of explaining the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add configurations from other embodiments to the configuration of one embodiment. In addition, it is possible to add, delete, or replace parts of the configuration of each embodiment with other configurations.

[0036] While a roller chain was used as an example of the connecting section, it is not limited to this; any mechanism that performs a similar operation can be used. Furthermore, this deformation mechanism can be used for purposes other than prosthetic arms.

[0037] This specification includes disclosures of the following inventions. (First aspect) An elastically deformable support portion extending from the base end, It has multiple sprockets connected in series, adjacent sprockets are rotatably connected around a rotation axis that intersects the direction in which the sprockets are arranged, and a connecting section is arranged along the support section, A holding part that holds the connecting part relative to the support part, It has an actuator that changes the length of the connecting portion from the base end in the extending direction, A deformation mechanism characterized by the following:

[0038] (Second aspect) The connecting portion is folded back along the direction of the arrangement of the frames and has a first portion facing the support portion and a second portion positioned on the opposite side of the support portion, with the first portion in between. The actuator pulls the second portion toward the base end, thereby shortening the length of the second portion relative to the length of the first portion from the base end. A deformation mechanism according to a first embodiment, characterized by the following:

[0039] (Third aspect) The aforementioned retaining part is A fixing part that fixes a portion of the connecting part to the support part, The support portion and the connecting portion are integrally enclosed, and the cylindrical portion has multiple notches formed in the part facing the second portion. A deformation mechanism of a second embodiment characterized by the following:

[0040] (Fourth aspect) The connecting portion is folded back along the direction of the arrangement of the frames and has a first portion facing the support portion and a second portion positioned on the opposite side of the support portion, with the first portion in between. The actuator pushes the second portion in a direction away from the first portion, thereby shortening the length of the second portion relative to the length of the first portion in the extending direction. A deformation mechanism according to a first embodiment, characterized by the following:

[0041] (Fifth aspect) The aforementioned retaining part is A fixing part that fixes a portion of the connecting part to the support part, The support portion and the connecting portion are integrally enclosed, and the cylindrical portion has multiple notches formed in the part facing the second portion. A fourth embodiment of a deformation mechanism characterized by the following:

[0042] (Sixth aspect) The aforementioned connecting section is a roller chain. A deformation mechanism according to any of the first to fifth embodiments, characterized by the above.

[0043] (Seventh aspect) Having a deformation mechanism according to any of the first to sixth embodiments, A prosthetic arm characterized by the following features. [Explanation of Symbols]

[0044] 10, 20 Transformation Mechanism 11. Leaf spring 12 Periosteal members 13 Tendon sheath component 14 Roller chain 14A First chain section 14B Second chain section 15 Axial Actuator 16 Cam mechanism 17 Rotational actuator

Claims

1. An elastically deformable support portion extending from the base end, It has a plurality of sprockets connected in series, adjacent sprockets are rotatably connected around a rotation axis that intersects the direction in which the sprockets are arranged, and a connecting section is arranged along the support section, A holding part that holds the connecting part relative to the support part, It has an actuator that changes the length of the connecting portion from the base end in the extending direction, A deformation mechanism characterized by the following:

2. The connecting portion is folded back along the direction of the arrangement of the frames and has a first portion facing the support portion and a second portion positioned on the opposite side of the support portion, with the first portion in between. The actuator pulls the second portion toward the base end, thereby shortening the length of the second portion relative to the length of the first portion from the base end. The deformation mechanism according to feature 1.

3. The aforementioned retaining part is A fixing part that fixes a portion of the connecting part to the support part, The support portion and the connecting portion are integrally enclosed, and the cylindrical portion has multiple notches formed in the part facing the second portion. The deformation mechanism according to feature 2.

4. The connecting portion is folded back along the direction of the arrangement of the frames and has a first portion facing the support portion and a second portion positioned on the opposite side of the support portion, with the first portion in between. The actuator pushes the second portion in a direction away from the first portion, thereby shortening the length of the second portion relative to the length of the first portion in the extending direction. The deformation mechanism according to feature 1.

5. The aforementioned retaining part is A fixing part that fixes a portion of the connecting part to the support part, The support portion and the connecting portion are integrally enclosed, and the cylindrical portion has multiple notches formed in the part facing the second portion. The deformation mechanism according to feature 4.

6. The aforementioned connecting section is a roller chain. The deformation mechanism according to feature 1.

7. Having a deformation mechanism according to any one of claims 1 to 6, A prosthetic arm characterized by the following features.

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