JP2013085579A - Electrically operated artificial arm - Google Patents

Abstract

An electric prosthesis capable of reducing the weight while reducing the operation noise and improving the quietness is provided.
A driving source for rotating a first finger part 35 and a second finger part 42 supported by a prosthetic hand body 10 is formed of a polymer material, elastically deforms in response to voltage application, and stops voltage application. Accordingly, the polymer actuator 50 that reciprocates linearly by restoring the original shape is used. A power transmission unit 60 is provided for converting the linear reciprocating motion into a rotational motion and transmitting it to the finger portions 35 and 42. A link mechanism 70 having a plurality of levers including both finger portions 35 and 42 is provided in a power transmission path from the polymer actuator 50 to the both finger portions 35 and 42 via the power transmission portion 60. At least one of these levers functions by having a fulcrum, a force point and an action point. Then, the displacement input to the lever through the force point is amplified and output from the action point.
[Selection] Figure 1

Description

  The present invention relates to an electric prosthetic hand that is configured to open and close a plurality of fingers using a drive source that operates by energization.

  As electric prostheses, various electric prostheses have been developed in which a plurality of fingers that are rotatably supported by the prosthetic hand main body are opened and closed by a driving source. As a drive source, one that operates by energization is common. For example, Patent Document 1 describes an example in which a small electric motor is used as a drive source. Patent Document 2 describes an example in which an electromagnetic actuator is used as a drive source.

JP 2003-305069 A Japanese Patent Laid-Open No. 11-56885

  However, in Patent Document 1 using an electric motor as a drive source, since a plurality of gears are used for deceleration, an abnormal noise is generated at the meshing portion between the gears as the electric motor rotates, which is quiet. There is room for improvement.

  In Patent Documents 1 and 2, since most of both the electric motor and the electromagnetic actuator are made of metal, the ratio of the weight of the drive source to the total weight of the electric prosthesis is large. This is an impediment to reducing the weight of electric prostheses.

  This invention is made | formed in view of such a situation, The objective is to provide the electric prosthesis which can achieve weight reduction, reducing an operating noise and improving silence.

  In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that a plurality of finger portions each comprising a lever rotatably supported on a prosthetic hand main body and a polymer material are attached to the prosthetic hand main body. A polymer actuator that is elastically deformed in response to voltage application and linearly reciprocates by restoring to its original shape in response to voltage application stop, and is provided between the polymer actuator and each finger, The linear reciprocating motion of the polymer actuator is converted into a rotational motion and transmitted to each of the finger portions, and a power transmission portion for rotating the finger portion is provided, from the polymer actuator through the power transmission portion, A link mechanism having a plurality of levers including the fingers is provided in the power transmission path to each finger, and at least one of the levers of the link mechanism includes a fulcrum, a force point, Constitute a lever having a use point, said linkage amplifies the displacement amount input to the lever through the point of force, and summarized in that those outputs from the action point.

  According to the above configuration, the polymer actuator made of a polymer material is elastically deformed in response to voltage application, and reciprocates linearly by restoring to its original shape in response to the stop of voltage application. This linear reciprocating motion is converted into a rotational motion by the power transmission unit. At the time of conversion of the movement form, at least one of the levers functions as a “lever” in the link mechanism. That is, in the link mechanism, the amount of displacement input to the lever through the power point is amplified and output from the action point. As a result, even if the displacement amount due to the linear reciprocation of the polymer actuator is smaller than the displacement amount due to the opening and closing of the finger portion, each finger portion is opened and closed by amplification by the link mechanism, Opening takes place.

  By the way, since the polymer actuator used as a drive source for rotationally driving each finger is made of a polymer material, it is lighter than a drive source made of metal, for example, an electric motor or an electromagnetic actuator. is there. For this reason, the entire electric prosthesis is also lightweight.

  Further, when an electric motor is used as a drive source, a plurality of gears are required to decelerate the rotation of the electric motor and transmit it to each finger part. In the first aspect of the present invention, a polymer actuator that reciprocates linearly is used as a driving source, and a link mechanism is used to convert the linear reciprocating motion into a rotational motion. No gear is required. When multiple gears are used, sound is generated at the meshing part of the gears. However, since there is no such meshing in the case of a link mechanism, no sound is generated due to meshing. .

The gist of the invention according to claim 2 is that, in the invention according to claim 1, the link mechanism has a plurality of the levers constituting the lever.
According to said structure, the some lever of a link mechanism functions as a "lever". In the lever constituting the lever, the displacement amount input through the force point is amplified and output from the action point. By inputting and outputting the displacement amount a plurality of times, the amplification factor is increased and the displacement amount is amplified more.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the polymer actuator includes a dielectric layer formed of an insulating polymer material having elasticity, and a conductive polymer having elasticity. A pair of electrodes formed of a material and sandwiching the dielectric layer from both sides, and in response to voltage application between the electrodes, the dielectric layer is extended in a direction along the surface to stop the voltage application Accordingly, the gist of the present invention is to reciprocate linearly by contracting the dielectric layer to restore the original shape.

  According to the above configuration, when a voltage is applied between the pair of electrodes, one electrode has a positive charge and the other electrode has a negative charge. Here, current flows until a predetermined amount of electric charge is accumulated in each electrode, but current hardly flows when a predetermined amount of electric charge is accumulated. Therefore, less power is consumed for linear reciprocation of the polymer actuator.

  When both electrodes are charged as described above, a force (Coulomb force) in which positive charges and negative charges attract each other acts on both electrodes, and the dielectric layer is pressed from both sides by both electrodes. Since the dielectric layer is formed of an insulating polymer material having elasticity, when pressed from both sides by both electrodes as described above, the dielectric layer extends in a direction along its surface. Since the electrode is also formed of a conductive polymer material having elasticity, it extends following the dielectric layer.

  When the voltage application between the two electrodes is stopped, the charge accumulated in each electrode is released (discharged). Due to this discharge, the charge carried on each electrode is reduced, and the Coulomb force is reduced. As a result, the dielectric layer contracts in the direction along the surface of the dielectric layer by its own elastic restoring force. The elastic electrode also contracts following the dielectric layer.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, in the actuator main body constituting the main part of the polymer actuator, the dielectric layer and the two electrodes are spirally wound around a central axis. Thus, it is formed in a cylindrical shape, expands along the central axis according to the voltage application between the electrodes, and contracts along the central axis when the voltage application is stopped to restore the original shape. The main point is that

  According to said structure, a polymer actuator becomes a compact form (cylindrical shape) by winding a dielectric material layer and the electrode of the both sides spirally, and the mounting property to an artificial hand main body improves.

  The cylindrical actuator body extends in the direction along the central axis CL (the length direction of the actuator body) among the directions along the surface of the dielectric layer in response to voltage application between both electrodes. The actuator body is restored to its original shape by contracting in the direction (length direction) along the central axis CL in response to the stop of the voltage application between the electrodes.

  According to a fifth aspect of the present invention, in the invention according to the fourth aspect, the prosthetic hand main body is provided with a movable member coupled to the link mechanism so as to be movable along the direction of expansion and contraction of the actuator main body. Further, the gist of the invention is that one end of the actuator body in the direction along the central axis is fixed to the prosthetic hand body as a fixed end so as not to move, and the other end is attached to the movable member as a movable end.

  According to the above configuration, when a voltage is applied between the two electrodes, the actuator body extends from the fixed end that is one end in the direction along the central axis such that the movable end that is the other end is away from it. Along with this, the movable member attached to the movable end moves to the front side in the extending direction of the actuator body (the side where the movable end moves away from the fixed end). The displacement of the movable member at this time is transmitted to the link mechanism.

  When the voltage application is stopped, the actuator body contracts so that the movable end approaches the fixed end. Along with this, the movable member moves to the front side in the contraction direction of the actuator main body (the side where the movable end approaches the fixed end). The displacement of the movable member at this time is transmitted to the link mechanism.

  The invention according to claim 6 is the invention according to claim 5, wherein a plurality of the actuator bodies are used and arranged in a state in which the expansion and contraction directions are aligned, and the movable end for each actuator body is common. The gist is that it is attached to the movable member.

  According to said structure, if the force output from each actuator main body is small, the force added to a movable member will be small. However, according to the invention described in claim 6, since a plurality of actuator bodies are arranged in a state in which the expansion and contraction directions are aligned and each movable end is attached to a common movable member, a large force is applied to the movable member. Is added. As a result, a large force is transmitted to the link mechanism through the movable member, and the grasped object is grasped by the finger portion with a strong force.

  According to a seventh aspect of the present invention, in the invention according to the fifth or sixth aspect, the prosthetic hand main body is provided with a guide portion that guides the movable member to move in the telescopic direction of the actuator main body. It is a summary.

  According to said structure, when an actuator main body expands / contracts, a movable member will move with it. At this time, the movable member is guided by the guide portion to move in the expansion / contraction direction of the actuator body. Therefore, the expansion and contraction (linear reciprocation) of the actuator body is transmitted to the link mechanism through the movable member that moves as described above with little loss.

  The invention according to claim 8 is the invention according to any one of claims 5 to 7, wherein the link mechanism is disposed between the lever and the movable member constituting the lever, and The gist is to include a drive lever that is displaced in the expansion and contraction direction as the actuator body expands and contracts.

  According to the above configuration, when the actuator body expands and contracts, the movable member is displaced accordingly, and the displacement is transmitted to the link mechanism. In the link mechanism, the drive lever disposed between the lever constituting the lever and the movable member is displaced in the expansion / contraction direction of the actuator body. Therefore, the expansion / contraction (linear reciprocation) of the actuator body is transmitted to the link mechanism with little loss through the drive lever that is displaced as described above.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the prosthetic hand main body, each finger part and the power transmission part are each formed of a polymer material. Is the gist.

  According to said structure, the prosthetic hand main body, each finger part, and power transmission part which were each formed with the polymeric material are lightweight. Therefore, the electric prosthetic hand having the prosthetic hand main body, each finger part, and the power transmission part as constituent members is lighter than those in which at least one of the constituent members is made of metal.

  According to the electric prosthesis of the present invention, using a polymer actuator that undergoes linear reciprocation by elastically deforming in response to voltage application and restoring its original shape in response to the stop of voltage application, displacement associated with the linear reciprocation Since the amount is amplified and transmitted to a plurality of finger portions, and the finger portions are rotated (opened / closed), it is possible to reduce the weight while reducing the operating noise and improving the quietness.

The perspective view which shows the whole structure of the electric prosthesis in one Embodiment which actualized this invention. The perspective view which shows the state from which the polymer actuator was removed from the electric prosthesis of FIG. It is a figure which shows the polymer actuator in the electric prosthesis of one Embodiment, (A) is sectional drawing which shows notionally the cross-section of the polymer actuator contracted according to the stop of voltage application, (B) is according to voltage application Sectional drawing which shows notionally the cross-sectional structure of the extended | stretched polymer actuator, (C) is a perspective view which shows notionally the structure of the polymer actuator of the expanded state. The cross-sectional view of the electric prosthetic hand in one embodiment. The bottom sectional view of the electric prosthesis in one embodiment. The schematic diagram which shows schematic structure of an adjustment board part and power transmission part when both fingers are opened in the electric prosthesis of one embodiment. The schematic diagram which shows schematic structure of an adjustment board part and power transmission part when both finger parts are closed in the electric prosthetic hand of one Embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the electric prosthetic hand of the present embodiment mainly includes a prosthetic hand body 10, a plurality of fingers, a polymer actuator 50, and a power transmission unit 60. Of the above-described members constituting the electric prosthetic hand, the prosthetic hand body 10, each finger part, and the power transmission part 60 are each made of a high-strength synthetic resin such as a polymer material, for example, engineering plastic.

Next, each component of the electric prosthesis will be described.
<Prosthetic hand body 10>
The prosthetic hand main body 10 forms a skeleton portion of the electric prosthetic hand. Here, in the electric prosthetic hand, when the direction toward the portion corresponding to the person's wrist is “rear” and the direction toward the portion corresponding to the fingertip is “front”, the prosthetic body 10 has an elongated shape in the front-rear direction. Yes. The prosthetic hand main body 10 has an accommodating portion 11 whose rear surface is open. The open part of the rear surface of the accommodating part 11 is blocked by a rear wall part 12 which is a part corresponding to a wrist of a human hand. The rear wall portion 12 has a plate shape and is orthogonal to the front-rear direction. The rear wall portion 12 is fastened to a plurality of locations at the rear portion of the prosthetic hand main body 10 by bolts 13 and nuts 14. A shaft support hole 15 is penetrated forward and backward at a plurality of locations (9 locations in the present embodiment) of the rear wall portion 12.

  The prosthetic hand main body 10 has a pair of opposing wall portions 16 and 17 on the side of the housing portion 11. The opposing wall portion 16 on one side (each right side in FIGS. 1 and 2) is a portion corresponding to the back of a person's hand (the surface from the wrist to the base of the finger that is outside when the hand is grasped). The other (left side in FIG. 2) opposing wall portion 17 is a portion corresponding to the palm (the surface from the wrist to the base of the finger that is inside when the hand is grasped).

  The prosthetic hand body 10 has a front wall portion 18 in front of the housing portion 11. In the front wall portion 18, shaft support holes (not shown) are passed through the front and rear at a plurality of locations in front of the shaft support hole 15. The front wall portion 18 has a plate shape and is orthogonal to the front-rear direction. A lid portion 19 is disposed on the front side of the front wall portion 18 and in the vicinity of the front wall portion 18, and the shaft support hole of the front wall portion 18 is covered with the lid portion 19. . The lid portion 19 is fastened to a plurality of locations on the front wall portion 18 with bolts 21 and nuts (not shown).

The prosthetic hand main body 10 has a pair of support wall portions 23 at locations close to the front wall portion 18. Both supporting wall portions 23 are separated from each other with a certain gap.
In the accommodating part 11, the movable member 24 connected with the link mechanism 70 mentioned later is arrange | positioned so that a movement in the front-back direction is possible. The movable member 24 includes a slide plate portion 25 extending in the front-rear direction, a movable wall portion 26 extending from the rear end of the slide plate portion 25 in a direction perpendicular to the slide plate portion 25 (upward in FIGS. 1 and 2), And an adjusting plate portion 28 that extends in the direction and that can be adjusted in the longitudinal direction with respect to the slide plate portion 25. The movable wall portion 26 is located at a location close to the front of the rear wall portion 12. In the movable wall portion 26, attachment holes 27 having a diameter larger than that of the shaft support hole 15 are penetrated in front and rear at a plurality of positions corresponding to the shaft support holes 15 of the front wall portion 18 and the rear wall portion 12. .

  Guide walls 29 having guide grooves 29A extending in the front-rear direction are formed in the opposing wall portions 16, 17, and both side portions of the slide plate portion 25 can be slid in the front-rear direction in the guide grooves 29A. Is engaged.

  As shown in FIGS. 2 and 5, the adjustment plate portion 28 is formed with a pair of adjustment holes 31 that extend in the front-rear direction. Then, the adjustment plate portion 28 is inserted into the slide plate portion 25 so as to be immovable, and is inserted through the adjustment holes 31 so as to be movable, and the nut 33 screwed into the bolt 32 is connected to the adjustment plate portion 28. It is concluded to. By adjusting the front / rear position of the bolt 32 in each adjustment hole 31, the front / rear position of the adjustment plate part 28 with respect to the slide plate part 25 can be adjusted.

<Finger>
As shown in FIGS. 4 and 5, the plurality of finger parts are composed of a first finger part 35 and a second finger part 42 in the present embodiment. The first finger portion 35 corresponds to an index finger, a middle finger, or the like of a human hand, and a front end thereof constitutes a fingertip 36. The first finger portion 35 is rotatably supported by a rotation center shaft 37 provided between the support wall portions 23 and near the opposing wall portion 16. In the first finger portion 35, a long hole 38 extending at an angle with respect to the front-rear direction is formed on the rear side of the rotation center shaft 37 so as to approach the second finger portion 42 toward the rear portion (see FIG. 4). ). In the first finger portion 35, a connecting shaft 39 is provided in front of the rotation center shaft 37 and on the second finger portion 42 side.

  The second finger portion 42 corresponds to the thumb of a human hand, and the front end thereof constitutes the fingertip 43. The second finger portion 42 is rotatably supported by a rotation center shaft 44 provided between the support wall portions 23 and near the opposing wall portion 17. In the second finger portion 42, a connecting shaft 45 is provided on the rear side of the rotation center shaft 44 and on the first finger portion 35 side.

<Polymer actuator 50>
The polymer actuator 50 is an actuator that is made of a polymer material, elastically deforms in response to voltage application, and reciprocates linearly by restoring to its original shape in response to the stop of voltage application. It is equivalent to muscle.

  The polymer actuator 50 includes a so-called dielectric system and an ion system. In this embodiment, a dielectric polymer actuator is employed in terms of displacement, generating force, and the like.

  FIG. 3C shows the dielectric polymer actuator 50 in a state of being developed in a planar shape. As shown in FIG. 3C, the polymer actuator 50 includes a dielectric layer 51 formed of an insulating insulating polymer material having elasticity, and a dielectric layer formed of an elastic conductive polymer material. And a pair of electrodes 52 and 53 sandwiching 51 from both sides.

The dielectric layer 51 is made of a polymer compound (polymer gel or the like) whose crosslink point moves, for example, polyrotaxane.
Both electrodes 52 and 53 are made of general-purpose rubber or the like. One electrode 52 is connected to the positive pole of the power source 54, and the other electrode 53 is connected to the negative pole of the power source 54 via the switch 55.

  The polymer actuator 50 extends the dielectric layer 51 in the direction along the surface in response to the voltage application between the electrodes 52 and 53, and contracts the dielectric layer 51 in response to the stop of the voltage application. A linear reciprocating motion is performed by restoring the shape.

  As shown in FIGS. 3A and 3B, the actuator main body 56 constituting the main part of the polymer actuator 50 has a dielectric layer 51 and electrodes 52 and 53 on both sides spirally around the central axis CL. Is formed into a cylindrical shape having both ends opened. As described above, the actuator main body 56 has a compact form and has good mountability to the prosthetic hand main body 10.

  In addition, as shown in FIG. 3B, the actuator body 56 is applied in the direction along the central axis CL (the actuator body 56 among the directions along the surface of the dielectric layer 51 by applying a voltage between the electrodes 52 and 53. As shown in FIG. 3A, when the voltage application is stopped, the original shape is restored by contracting in the direction along the central axis CL (length direction).

  The displacement amount of the polymer actuator 50 accompanying expansion / contraction of the actuator body 56 is smaller than the displacement amount accompanying opening / closing of both finger portions 35, 42, but in FIGS. 3 (A) and 3 (B), for convenience of explanation. The state of expansion and contraction of the actuator body 56 is exaggerated.

  Cylindrical pipes 57 are respectively inserted and fixed in both openings in the direction along the central axis CL of the actuator body 56. In the actuator body 56, a coil spring 58 is disposed between the pipes 57 in a compressed state. The coil spring 58 urges both the pipes 57 in directions away from each other (left and right directions in FIGS. 3A and 3B). The biasing force of the coil spring 58 is transmitted to the actuator body 56 through both pipes 57. Therefore, the actuator body 56 is biased so as to extend in the direction along the central axis CL. Such a configuration is adopted because when the dielectric layer 51 is extended in the direction along the surface, the extension of the dielectric layer 51 in the direction along the vortex centered on the central axis CL is suppressed as much as possible. This is because the amount of displacement of the actuator main body 56 in the direction along the line is made as large as possible.

  As shown in FIG. 1, in this embodiment, a plurality of polymer actuators 50 having the above-described configuration are used. The actuator main bodies 56 of these polymer actuators 50 are arranged in a state where the expansion and contraction directions are aligned in the front-rear direction. That is, in this embodiment, the expansion / contraction direction of the actuator body 56 for each polymer actuator 50 matches the front-rear direction.

  As shown in FIGS. 1 and 3, a shaft 59 extending in the front-rear direction is inserted through the actuator body 56 for each polymer actuator 50, the pipe 57 for each actuator body 56, and the coil spring 58 for each actuator body 56. ing. The front end portion of each shaft 59 is exposed forward from the front pipe 57 and is inserted and fixed in the shaft support hole of the front wall portion 18. A rear end portion of each shaft 59 is exposed rearward from the rear pipe 57 and is inserted and fixed in the shaft support hole 15 of the rear wall portion 12. The front end of each actuator body 56 is fixed to the front wall portion 18 as a fixed end 56 </ b> A and cannot move relative to the prosthetic hand body 10. A rear end portion of each actuator body 56 is attached to the movable wall portion 26 as a movable end 56B.

<Power transmission unit 60>
The power transmission unit 60 is provided between each actuator body 56 (movable member 24) and each finger portion 35, 42 (rotation center shafts 37, 44), and performs linear reciprocation of each actuator body 56 (movable member 24). This is converted into a rotational motion and transmitted to the finger portions 35 and 42 to rotate (open and close) the finger portions 35 and 42.

  FIG. 6 shows a schematic configuration of the adjustment plate portion 28 and the power transmission portion 60 of the movable member 24 when the finger portions 35 and 42 are opened. FIG. 7 shows a schematic configuration of the adjustment plate portion 28 and the power transmission portion 60 of the movable member 24 when the finger portions 35 and 42 are closed. As shown in FIGS. 6 and 7, the power transmission unit 60 includes a plurality of levers. The plurality of levers includes a single drive lever 61 and a pair of front and rear driven levers 62 and 63.

  The rear driven lever 63 is disposed in an inclined state with respect to the front-rear direction so as to approach the second finger portion 42 toward the rear side. The rear driven lever 63 is rotatably supported by the bottom wall portion 20 of the prosthesis body 10 by a rotation center shaft 64 provided at the rear end portion. A shaft 65 is provided at the front end portion of the rear driven lever 63, and this shaft 65 is movably engaged with the elongated hole 38 of the first finger portion 35 in the extending direction of the elongated hole 38. Are combined.

  A connecting shaft 30 is provided at the front end of the adjusting plate 28 (see FIG. 2). Further, in the rear driven lever 63, a connecting shaft 66 is provided at a position in front of the connecting shaft 30 (between the shaft 65 and the rotation center shaft 64). A driving lever 61 extending in the front-rear direction is connected to the adjusting plate portion 28 and the rear driven lever 63 at the connecting shafts 30 and 66.

  The front driven lever 62 is arranged in an inclined state so as to approach the second finger portion 42 toward the rear side. The front end portion of the front driven lever 62 is connected to the connecting shaft 39 of the first finger portion 35, and the rear end portion is connected to the connecting shaft 45 of the second finger portion 42.

  The link mechanism 70 is configured by adding the first finger 35 and the second finger 42 described above as levers to the plurality of levers (the drive lever 61 and the driven levers 62 and 63) in the power transmission unit 60. Yes. The link mechanism 70 having a plurality of levers including both finger portions 35 and 42 is provided in a power transmission path from the polymer actuator 50 to the both finger portions 35 and 42 via the power transmission portion 60.

  As shown in FIG. 6, the rear driven lever 63 constitutes a “lever” that uses the connecting shaft 66 as a force point, the rotation center shaft 64 as a fulcrum, and the shaft 65 as an action point. In this rear driven lever 63, the length L1 between the force point (connection shaft 66) and the fulcrum (rotation center shaft 64) is greater than the length L2 between the force point (connection shaft 66) and the action point (shaft 65). Is also set short.

  The first finger portion 35 functioning as a lever constitutes a “lever” having the shaft 65 as a force point, the rotation center shaft 37 as a fulcrum, and the fingertip 36 as an action point. In the first finger portion 35, the length L3 between the force point (shaft 65) and the fulcrum (rotation center axis 37) is longer than the length L4 between the fulcrum (rotation center axis 37) and the action point (fingertip 36). Is also set short.

  Accordingly, the expansion / contraction (displacement) of the polymer actuator 50 constitutes a lever (insulator) between the time when it is input to the drive lever 61 via the movable member 24 and is output from the fingertip 36 of the first finger portion 35. The two levers (the driven lever 63 and the first finger portion 35) are passed through.

  The second finger portion 42 functioning as a lever constitutes a “lever” having the connecting shaft 45 as a force point, the rotation center shaft 44 as a fulcrum, and the fingertip 43 as an action point. In the second finger portion 42, the length L5 between the force point (connection shaft 45) and the fulcrum (rotation center axis 44) is the length L6 between the fulcrum (rotation center axis 44) and the action point (fingertip 43). Is set shorter.

  Therefore, the expansion / contraction (displacement) of the polymer actuator 50 constitutes a lever (insulator) between the time when it is input to the drive lever 61 via the movable member 24 and is output from the fingertip 43 of the second finger portion 42. The two levers (the driven lever 63 and the second finger portion 42) are passed through.

The electric prosthesis of the present embodiment is configured as described above. Next, the operation of this electric prosthetic hand will be described.
1, FIG. 3 (A), (C) and FIG. 6 show the case where the switch 55 (FIG. 3 (C)) is opened and voltage application between the electrodes 52 and 53 of the actuator body 56 is stopped. The state of the electric prosthetic hand is shown. In this state, in the polymer actuator 50, electric charges are not accumulated in the electrodes 52 and 53 due to discharge (discharge of electric charges), and the actuator main body 56 is contracted (FIG. 3A). Since the front end of the actuator body 56 is fixed to the front wall portion 18 of the prosthetic hand body 10 as a fixed end 56A, the front-rear position thereof is not changed. On the other hand, the rear end of the actuator body 56 is a movable end 56 </ b> B, which is only attached to the movable wall portion 26 and is not fixed to the prosthetic hand body 10. The rear end of the actuator main body 56 is located at the foremost position in the movable range. The movable member 24 attached to the movable end 56B (rear end) of the actuator body 56 and allowed to move in the front-rear direction is located at the foremost position in the movable range. A connecting shaft 66 that connects the drive lever 61 and the rear driven lever 63 is located in front of the rotation center shaft 64. The rear driven lever 63 is inclined at a relatively small angle with respect to the front-rear direction. The shaft 65 is located at the front end of the long hole 38. The fingertip 36 of the first finger portion 35 is located at a position farthest from the fingertip 43 of the second finger portion 42. Along with this, the connecting shaft 39 of the first finger portion 35 is located at the foremost location in the movable range. The connecting shaft 45 of the second finger portion 42 is located at the foremost location in the movable range. The fingertip 43 of the second finger portion 42 is located at a position farthest from the fingertip 36 of the first finger portion 35. As a result, the fingertips 36 and 43 of both finger portions 35 and 42 are greatly separated from each other.

  When the object to be grasped (not shown) is gripped by the electric prosthetic hand from the above state, the switch 55 (FIG. 3C) is closed. A voltage is applied between the electrodes 52 and 53 of the actuator body 56. One electrode 52 has a positive charge, and the other electrode 53 has a negative charge.

  Here, a current flows until a predetermined amount of electric charge is accumulated in each of the electrodes 52 and 53. However, when a predetermined amount of electric charge is accumulated, the electric current hardly flows. The fact that almost no current flows means that a discharge is generated after a certain amount of electrification is accumulated, so that a current flows to make up for the reduced charge due to the discharge.

  When both electrodes 52 and 53 are charged as described above, a force (Coulomb force) that attracts positive and negative charges to each other acts on both electrodes 52 and 53, and dielectric layer 51 is pressed from both sides. And extend in a direction along the surface. Since the electrodes 52 and 53 are also made of a conductive polymer material having elasticity, they extend following the dielectric layer 51.

  The actuator body 56 formed in a cylindrical shape by winding the dielectric layer 51 and the electrodes 52 and 53 on both sides of the dielectric layer 51 around the central axis CL in the direction along the surface of the dielectric layer 51 is the central axis. It extends in the direction (length direction) along CL.

  In this extension, the fixed end 56A (front end) of the actuator body 56 is fixed to the front wall portion 18 of the prosthetic hand body 10, while the movable end 56B is not fixed to the prosthetic hand body 10. Therefore, the actuator body 56 extends rearward, which is a direction in which the movable end 56B moves away from the fixed end 56A. Accordingly, the movable member 24 to which the movable end 56B is attached moves in the extending direction (backward) of the actuator body 56.

  At this time, the slide plate portion 25 of the movable member 24 is guided by the guide portion 29 to move in the extending direction (backward) of the actuator body 56 (see FIG. 2). Through the movable member 24 that moves as described above, the displacement amount associated with the extension of the polymer actuator 50 is transmitted to the link mechanism 70 with little loss.

  Further, with the above movement of the movable member 24 (adjustment plate portion 28), the drive lever 61 is pulled backward while maintaining the posture of extending in the front-rear direction (extension direction of the actuator body 56). The pulling force at this time is transmitted to the rear driven lever 63 through the connecting shaft 66, so that the driven lever 63 rotates counterclockwise in FIG. This rotation increases the angle formed with respect to the front-rear direction of the rear driven lever 63. The shaft 65 moves to the side away from the second finger portion 42 behind the rotation center shaft 37. At this time, the shaft 65 moves to the rear end of the long hole 38 along the direction in which the long hole 38 extends, so that the drive lever 61 maintains a posture extending in the front-rear direction.

  The rotation of the rear driven lever 63 is transmitted to the first finger portion 35 through the shaft 65, and the first finger portion 35 rotates in the clockwise direction in FIG. By this rotation, as shown in FIG. 7, the fingertip 36 of the first finger portion 35 approaches the fingertip 43 of the second finger portion 42. Further, the connecting shaft 39 moves to the second finger portion 42 side by the rotation of the first finger portion 35, and the front driven lever 62 connected to the connecting shaft 39 moves to the second finger portion 42 side. The movement of the front driven lever 62 is transmitted to the rear end of the second finger portion 42 via the connecting shaft 45, and the second finger portion 42 rotates counterclockwise in FIG. To turn. By this rotation, as shown in FIG. 7, the fingertip 43 of the second finger portion 42 approaches the fingertip 36 of the first finger portion 35, and the object to be grasped is gripped between the fingertips 43 and 36.

  On the other hand, when the switch 55 (FIG. 3C) is opened again from the above state, the voltage application between the electrodes 52 and 53 of the actuator body 56 is stopped. By this stop, the electric charge accumulated in both electrodes 52 and 53 is discharged (discharged). Due to this discharge, the electric charges carried on the electrodes 52 and 53 are reduced, and the Coulomb force is reduced. As a result, the dielectric layer 51 contracts in the direction along the surface of the dielectric layer 51 by its own elastic restoring force.

  The actuator body 56 formed in a cylindrical shape by winding the dielectric layer 51 and the electrodes 52 and 53 in a spiral shape is along the central axis CL of the actuator body 56 in the direction along the surface of the dielectric layer 51. It shrinks in the direction (length direction) (FIG. 3A).

The electrodes 52 and 53 formed of a conductive polymer material having elasticity contracts in the direction along the central axis CL following the dielectric layer 51.
During this contraction, the actuator body 56 contracts forward, which is the direction in which the movable end 56B approaches the fixed end 56A. Accordingly, the movable member 24 moves in the contraction direction (forward) of the actuator body 56.

  At this time, the slide plate portion 25 of the movable member 24 is guided by the guide portion 29 to move in the contraction direction (forward) of the actuator body 56. Through the movable member 24 that moves as described above, the amount of displacement accompanying the contraction of the polymer actuator 50 is transmitted to the link mechanism 70 with little loss.

  Further, the drive lever 61 is pressed forward with the displacement of the movable member 24 (adjustment plate portion 28). The pressing force at this time is transmitted to the rear driven lever 63 through the connecting shaft 66, so that the driven lever 63 rotates in the clockwise direction in FIG. By this rotation, the angle formed with respect to the front-rear direction of the rear driven lever 63 is reduced. The shaft 65 moves to the side closer to the second finger portion 42 behind the rotation center shaft 37. At this time, the shaft 65 moves to the front end along the direction in which the long hole 38 extends, so that the posture in which the drive lever 61 extends in the front-rear direction is maintained.

  The rotation of the rear follower lever 63 is transmitted to the first finger portion 35 through the shaft 65, and the first finger portion 35 rotates counterclockwise in FIG. . By this rotation, as shown in FIG. 6, the fingertip 36 of the first finger portion 35 moves away from the fingertip 43 of the second finger portion 42. Further, the rotation of the first finger 35 moves the connecting shaft 39 away from the second finger 42, and the front driven lever 62 connected to the connecting shaft 39 moves toward the first finger 35. Moving. The movement of the front driven lever 62 is transmitted to the rear end of the second finger portion 42 via the connecting shaft 45, and the second finger portion 42 rotates in the clockwise direction in FIG. Rotate. By this rotation, as shown in FIG. 6, the fingertip 43 of the second finger portion 42 moves away from the fingertip 36 of the first finger portion 35, and the gripping of the gripping object between the fingertips 43, 36 is released ( The gripping object is released).

  As described above, the expansion and contraction (linear reciprocating motion) of the actuator body 56 is converted into a rotational motion by the power transmission unit 60 and transmitted to the first finger unit 35 and the second finger unit 42. At the time of conversion and transmission of power by the power transmission unit 60, the link mechanism 70 includes a rear driven lever 63, a first finger portion 35 as a lever, and a second finger portion 42 as a lever.梃 子) ”.

  That is, as shown in FIG. 6, in a lever (insulator) constituted by the rear driven lever 63, the connecting shaft 66 is a force point, the rotation center shaft 64 is a fulcrum, and the shaft 65 is an action point. The In the rear driven lever 63, the length L1 between the force point (connection shaft 66) and the fulcrum (rotation center shaft 64) is longer than the length L2 between the force point (connection shaft 66) and the action point (shaft 65). Also short. Therefore, in the link mechanism 70, the displacement amount of the drive lever 61 input to the rear driven lever 63 through the force point (connection shaft 66) is amplified by (L2 / L1) times, and the action point (shaft 65). Is output from.

  Moreover, in the lever (insulator) comprised by the 1st finger part 35, the axis | shaft 65 is made into a power point, the rotation center axis | shaft 37 is made into a fulcrum, and the fingertip 36 is made into an action point. In the first finger portion 35, the length L3 between the force point (shaft 65) and the fulcrum (turning center axis 37) is longer than the length L4 between the fulcrum (turning center axis 37) and the action point (fingertip 36). Also short. From this, in the link mechanism 70, the displacement amount of the driven lever 63 input to the first finger portion 35 (lever) through the force point (shaft 65) is amplified by (L4 / L3) times, and the action point (fingertip 36). ) Is output.

  Accordingly, the expansion / contraction (linear reciprocation) of the polymer actuator 50 is input to the link mechanism 70 (drive lever 61) via the movable member 24 and output from the action point (fingertip 36) of the first finger portion 35. In the meantime, the amount of displacement accompanying the expansion / contraction (linear reciprocation) is amplified twice. In this case, the displacement amount is amplified by (L2 / L1) · (L4 / L3) times.

  Further, in the lever (insulator) constituted by the second finger portion 42, the connecting shaft 45 is a force point, the rotation center shaft 44 is a fulcrum, and the fingertip 43 is an action point. In this second finger portion 42, the length L5 between the force point (connection shaft 45) and the fulcrum (rotation center axis 44) is the length L6 between the fulcrum (rotation center axis 44) and the action point (fingertip 43). Shorter than. From this, in the link mechanism 70, the displacement amount of the front driven lever 62 (the connecting shaft 39 accompanying the rotation of the first finger portion 35) input to the second finger portion 42 (lever) through the force point (the connecting shaft 45). Is equal to (L6 / L5) times and output from the point of action (fingertip 43).

  Accordingly, the expansion / contraction (linear reciprocation) of the polymer actuator 50 is input to the link mechanism 70 (drive lever 61) via the movable member 24 and output from the action point (fingertip 43) of the second finger portion 42. In the meantime, the amount of displacement accompanying the expansion / contraction (linear reciprocation) is amplified twice. In this case, the displacement amount is amplified by (L2 / L1) · (L6 / L5) times.

  As a result, although the amount of displacement accompanying expansion and contraction of the actuator body 56 is smaller than the amount of displacement accompanying opening and closing of both finger portions 35 and 42, amplification is performed by the link mechanism 70, whereby each finger portion 35 and 42. Is pivoted (opened and closed), and the object to be grasped is preferably grasped and released.

  Here, if the force generated when each actuator body 56 extends is small, the force applied to the movable member 24 is small. However, in this embodiment, a plurality of polymer actuators 50 are used, and the actuator main bodies 56 are arranged in a state where the expansion and contraction directions are aligned, and the movable end 56B (rear end) for each actuator main body 56 is common. Since it is attached to the movable member 24 (movable wall portion 26), a large force is applied to the movable member 24 via the movable wall portion 26. The force applied to the first finger part 35 and the second finger part 42 via the link mechanism 70 increases, and the object to be grasped is grasped with a large force.

  By the way, the polymer actuator 50 used as a driving source for rotationally driving the first finger part 35 and the second finger part 42 is a polymer material (dielectric layer 51: insulating polymer material, electrodes 52, 53: Since it is made of a conductive polymer material), it is lighter than a drive source made of metal, for example, an electric motor or an electromagnetic actuator. For this reason, the entire electric prosthesis is also lightweight.

  When an electric motor is used as a drive source, a plurality of gears are required to decelerate the rotation of the electric motor and transmit it to the finger portions 35 and 42. In this regard, in this embodiment, a polymer actuator 50 that expands and contracts (linear reciprocating motion) is used as a drive source, and a link mechanism 70 is used to convert the expansion and contraction (linear reciprocating motion) into a rotational motion. Therefore, the gear as described above is unnecessary. When a plurality of gears are used, a sound is generated at the meshing portion of the gears as the electric motor rotates. However, in the case of the link mechanism 70, there is no such meshing. The resulting sound does not occur.

According to the embodiment described in detail above, the following effects can be obtained.
(1) As a drive source for rotating a pair of fingers (first finger 35, second finger 42) supported by the prosthetic hand body 10, it is formed of a polymer material and elastically deforms in response to voltage application. Then, a polymer actuator 50 that reciprocates linearly by restoring the original shape according to the stop of voltage application is used. A power transmission unit 60 is provided that converts the linear reciprocating motion of the polymer actuator 50 into a rotational motion and transmits it to the finger portions 35 and 42. A link mechanism 70 having a plurality of levers including both finger portions 35 and 42 is provided in a power transmission path from the polymer actuator 50 to the both finger portions 35 and 42 via the power transmission portion 60. At least one of these levers (the driven lever 63, the first finger portion 35, and the second finger portion 42) is caused to function as a lever having a fulcrum, a force point, and an action point. Then, the amount of displacement input to the lever (driven lever 63, first finger portion 35, second finger portion 42) through the power point is amplified and output from the action point (FIG. 6).

  Therefore, a reduction mechanism using a plurality of gears necessary for a conventional electric prosthesis using an electric motor as a drive source is unnecessary, and the structure can be simplified. Accordingly, maintenance of the electric prosthesis can be facilitated.

In addition, unlike the case where an electric motor is used as the drive source, it is possible to reduce the operating noise by reducing the noise caused by the meshing between the gears and to improve the quietness.
Furthermore, the use of the polymer actuator 50 made of a polymer material as a drive source can reduce the weight of the entire electric prosthesis.

(2) A plurality of levers (the driven lever 63, the first finger portion 35, and the second finger portion 42) in the link mechanism 70 are caused to function as “lever” (FIG. 6).
Therefore, for each lever (follower lever 63, first finger part 35, second finger part 42) constituting a lever (a lever), the displacement amount input through the power point is amplified and output from the action point. The displacement amount can be amplified by the amplification factor. Even if the amount of displacement accompanying expansion and contraction of the polymer actuator 50 is small, the finger portions 35 and 42 can be rotated and opened and closed.

  (3) As the polymer actuator 50, a dielectric layer 51 formed of an insulating polymer material having elasticity, and a pair of electrodes formed of an elastic conductive polymer material and sandwiching the dielectric layer 51 from both sides What is provided with 52,53 is used (FIG.3 (C)).

  Therefore, by applying a voltage between the electrodes 52 and 53, the dielectric layer 51 is expanded in the direction along the surface, and the dielectric layer 51 is contracted in the direction along the surface in response to the stop of the voltage application. Thus, the effects (1) and (2) can be obtained.

  In addition, a current flows until a predetermined amount of charge is accumulated in each electrode 52, 53. However, since a current hardly flows when a predetermined amount of charge is accumulated, it is consumed for operation (extension / contraction) of the polymer actuator 50. Less power is required. As a result, a battery having a small capacity can be used as the power source 54, and convenience is improved.

  (4) By winding the dielectric layer 51 and the electrodes 52 and 53 in a spiral around the central axis CL, an actuator body 56 that forms the main part of the polymer actuator 50 is formed in a cylindrical shape (see FIG. 3 (A), (B)).

Therefore, the actuator main body 56 can be made into a compact form (cylindrical), and the mountability to the prosthetic hand main body 10 can be improved (FIG. 1).
Further, by applying voltage, the actuator body 56 can be extended in the direction along the central axis CL (the length direction of the actuator body 56) among the directions along the surface of the dielectric layer 51 (FIG. 3B). . In response to the stop of the voltage application, the actuator body 56 can be contracted in the direction along the central axis CL (FIG. 3A).

  (5) The movable member 24 connected to the link mechanism 70 is provided so as to be movable in the expansion / contraction direction of the actuator body 56 with respect to the artificial hand body 10. One end (front end) of the actuator body 56 in the length direction is fixed to the prosthetic hand body 10 as a fixed end 56A so as not to move, and the other end (rear end) is attached to the movable member 24 (movable wall portion 26) as a movable end 56B. (FIGS. 1 and 2).

  Therefore, the actuator main body 56 is extended so that the movable end 56B (rear end) moves away from the fixed end 56A (front end), and the movable member 24 attached to the movable end 56B (rear end) of the actuator main body 56 is attached to the actuator main body 56. 56 can be moved to the front side in the extending direction (the side where the movable end 56B moves away from the fixed end 56A). The displacement of the movable member 24 at this time can be transmitted to the link mechanism 70 (drive lever 61).

  (6) A plurality of actuator bodies 56 are arranged in a state where the expansion and contraction directions are aligned, and a movable end 56B (rear end) for each actuator body 56 is attached to a common movable member 24 (movable wall portion 26) ( FIG. 1).

  Therefore, even if the force output from each polymer actuator 50 is small, a large force can be applied to the movable member 24. A large force is transmitted to the link mechanism 70 through the movable member 24, and the object to be grasped can be grasped by the finger portions 35 and 42 with a strong force.

  (7) The guide walls 29 having the guide grooves 29A are provided on the opposing wall portions 16 and 17 of the prosthetic hand body 10, respectively, and both side portions of the slide plate portion 25 of the movable member 24 are slidably engaged with the respective guide grooves 29A. (Fig. 2).

  Therefore, the guide member 29 can guide the movable member 24 to move in the expansion / contraction direction of the actuator body 56. As a result, the expansion and contraction (linear reciprocation) of the actuator body 56 can be transmitted to the link mechanism 70 through the movable member 24 that moves as described above with little loss.

  (8) A part of the link mechanism 70 is disposed between the rear driven lever 63 constituting the lever and the adjusting plate portion 28 of the movable member 24, and the actuator body 56 is expanded and contracted. The drive lever 61 is displaced in the expansion / contraction direction (FIG. 6).

  Therefore, the expansion / contraction (linear reciprocation) of the actuator main body 56 can be transmitted to the link mechanism 70 through the drive lever 61 that is displaced in the expansion / contraction direction of the actuator main body 56 with little loss.

(9) Each of the prosthetic hand body 10, each of the finger parts 35 and 42, and the power transmission part 60, which are constituent members of the electric prosthetic hand, is formed of a polymer material (high strength synthetic resin).
Therefore, it is possible to reduce the weight of each of the prosthetic hand main body 10, each finger part 35, 42 and the power transmission part 60, and to make the electric prosthetic hand lighter than those in which at least one component member is formed of metal. it can.

  (10) The polymer actuator 50 is formed of a flexible polymer material (dielectric layer 51: insulating polymer material having elasticity, electrodes 52 and 53: conductive polymer material having elasticity) (FIG. 3). (C)).

Therefore, even if a force for opening and closing these fingers 35 and 42 is applied from the outside, the force can be absorbed by expanding and contracting the actuator body 56.
Note that the present invention can be embodied in another embodiment described below.

<About the finger>
-The number of the some finger parts 35 and 42 may be changed into 3 or more.
<About polymer actuators>
In place of the dielectric polymer actuator 50 described above, an ion polymer actuator may be used.

  The ion-type polymer actuator is composed of a joined body of an ion exchange resin and an electrode. A typical example of this type of polymer actuator is that an electrode formed of a noble metal such as gold or platinum is bonded to both surfaces of a fluorine-based ion exchange resin film by electroless plating. In this polymer actuator, when a voltage of several volts is applied between the electrodes, ions move inside the ion exchange resin (the cation moves to the cathode side). A difference in swelling occurs between the front and back of the actuator, and the polymer actuator is elastically deformed. When the voltage application is stopped, the polymer actuator is restored to its original shape by the elastic restoring force. By these elastic deformation and restoration, the polymer actuator is reciprocated linearly.

<About the power transmission unit 60>
-By changing the configuration of the power transmission unit 60, contrary to the above embodiment, when the actuator body 56 of the polymer actuator 50 is extended, the first finger unit 35 and the second finger unit 42 are turned to the opening side. When the actuator main body 56 contracts, both the finger portions 35 and 42 may be rotated toward the closing side.

<About the link mechanism 70>
-The number of levers (including the first finger part 35 and the second finger part 42) constituting the link mechanism 70 that function as a lever (lion) has been changed to a number different from that of the above embodiment. Also good. The minimum value of this number is “1”. Further, the number of levers functioning as a lever may be three or more.

  In the levers constituting the lever, the displacement amount input through the force point is amplified and output from the action point. By setting the number of levers functioning as leverage to be 3 or more, the displacement amount is input and output three times or more, and the amplification factor is larger than that of the above embodiment (the displacement amount is amplified more). ) Is possible.

  However, as the number of levers constituting the lever increases, the installation space occupied by them increases. In addition, sliding resistance occurs between the levers, but as the number of levers increases, the number of places where sliding resistance occurs increases and the sliding resistance generated in the entire electric prosthesis increases. Therefore, it is desirable to set the number of levers in consideration of the advantages and disadvantages of the gain of the displacement, the installation space, and the sliding resistance.

<About the force that the first finger part 35 and the second finger part 42 close (hold the gripping object)>
• This force can be changed by adjusting the following factors:
(I) Voltage applied to the electrodes 52 and 53 for each actuator body 56. As this voltage increases, the force increases.

(Ii) Diameter of the actuator body 56. As the diameter increases, the force increases.
(Iii) The number of polymer actuators 50 that expand and contract. The force increases as the number increases.

  In this case, the number of polymer actuators 50 attached to the electric prosthesis may be changed, or the number of polymer actuators 50 to be applied with voltage may be changed by control or operation depending on the situation. Also good.

  DESCRIPTION OF SYMBOLS 10 ... Prosthetic hand main body, 24 ... Movable member, 29 ... Guide part, 35 ... 1st finger part (finger part), 42 ... 2nd finger part (finger part), 50 ... Polymer actuator, 51 ... Dielectric layer, 52 53 ... Electrode, 56 ... Actuator body, 56A ... Fixed end, 56B ... Movable end, 60 ... Power transmission part, 61 ... Drive lever, 70 ... Link mechanism, CL ... Center axis.

Claims (9)

A plurality of fingers each comprising a lever supported rotatably on the prosthetic hand body;
A polymer actuator that is formed of a polymer material and is attached to the prosthetic hand body, elastically deforms in response to voltage application, and reciprocates linearly by restoring the original shape in response to voltage application stop, and
A power transmission unit that is provided between the polymer actuator and each finger unit, converts the linear reciprocating motion of the polymer actuator into a rotational motion, transmits the rotational motion to each finger unit, and rotates the finger unit; With
A link mechanism having a plurality of levers including the fingers is provided in a power transmission path from the polymer actuator to the fingers through the power transmitter, and at least one of the link mechanisms The lever includes a lever having a fulcrum, a force point, and an action point, and the link mechanism amplifies a displacement amount input to the lever through the force point and outputs from the action point. An electric prosthesis that is characterized. The electric prosthetic hand according to claim 1, wherein the link mechanism includes a plurality of the levers constituting the lever. The polymer actuator includes a dielectric layer formed of an insulating insulating polymer material having elasticity, and a pair of electrodes formed of an elastic conductive polymer material and sandwiching the dielectric layer from both sides, In response to voltage application between the electrodes, the dielectric layer is stretched in a direction along its surface, and in response to the voltage application being stopped, the dielectric layer is contracted to restore its original shape. The electric prosthetic hand according to claim 1 or 2, which reciprocates. The actuator main body constituting the main part of the polymer actuator is formed in a cylindrical shape by winding the dielectric layer and the electrodes in a spiral shape around a central axis, and applies a voltage between the electrodes. The electric prosthetic hand according to claim 3, wherein the electric prosthetic hand extends along the central axis according to the pressure and contracts along the central axis when the voltage application is stopped to restore the original shape. A movable member connected to the link mechanism is provided in the prosthetic hand main body so as to be movable along the expansion / contraction direction of the actuator main body.
The electric prosthetic hand according to claim 4, wherein one end of the actuator body in the direction along the central axis is fixed to the prosthetic hand body as a fixed end so as not to move, and the other end is attached to the movable member as a movable end. A plurality of the actuator bodies are used, arranged in a state where the expansion and contraction directions are aligned,
The electric prosthesis according to claim 5, wherein the movable end of each actuator body is attached to a common movable member. The electric prosthetic hand according to claim 5 or 6, wherein the prosthetic hand main body is provided with a guide portion for guiding the movable member to move in the expansion / contraction direction of the actuator main body. The link mechanism includes a drive lever that is disposed between the lever constituting the lever and the movable member, and that is displaced in the expansion / contraction direction as the actuator body expands / contracts. The electric prosthetic hand according to one. The electric prosthetic hand according to any one of claims 1 to 8, wherein the prosthetic hand main body, the finger parts, and the power transmission part are each formed of a polymer material.

Images