JP2005058351A - Artificial muscle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact artificial muscle having a large amount of extension and contraction, excellent responsiveness and operation stability and a high degree of action freedom. <P>SOLUTION: This artificial muscle is composed of a linear motor for which flexibility is imparted to both of its two elements performing relative linear motions. Since the two elements perform the relative linear motion by the drive of the linear motor, expansion and contraction motions equivalent to those of the muscle fiber of an organism are obtained in the entire motor, and further, an extremely large stroke and high responsiveness and operation stability are obtained. Since the flexibility is provided in both of the two elements, the degree of freedom of actions is improved and natural motions close to the action of a human being, or the like, are realized with a single mechanism. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an artificial muscle using a linear motor.

  Artificial muscles are required to have a mechanism for performing expansion and contraction mainly based on external signals. As an example, Japanese Patent Laid-Open No. 11-215793 discloses an artificial muscle that uses attraction or repulsion between magnets for expansion and contraction (see Patent Document 1).

  The artificial muscle includes a plurality of electromagnets arranged apart from each other, and an expansion / contraction pad made of silicon rubber or the like interposed between the plurality of electromagnets. , Generating attraction or repulsion between the electromagnets and contracting or extending between the fulcrum provided at one end in the arrangement direction of the electromagnet and the stretchable pad and the action point provided at the other end It is.

  However, in this mechanism, since the amount of muscle expansion and contraction depends on the distance between the opposing magnets, there is a limit to the increase in the amount of expansion and contraction. Further, since the expansion / contraction operation is performed by elastic deformation of the expansion / contraction pad, there is a concern about responsiveness, and the rigidity may change due to external factors such as a use temperature and a use period, and the operation stability may be lowered.

  On the other hand, Japanese Patent Application Laid-Open No. 2002-144274 discloses a joint drive device using a linear motor (see Patent Document 2). Since this device is provided with a drive unit made of a linear motor and a deformed part made of an elastic body such as rubber or a spring, it is necessary to secure an installation space for the drive unit in addition to the deformed part. Space efficiency is poor. In addition, this drive device is ultimately equivalent to a joint structure using an actuator such as a hydraulic cylinder, and the obtained operation is limited to a mechanical device such as an arm of a power shovel. Accordingly, the degree of freedom of movement is low, and even if this is used as an artificial muscle, it is difficult to obtain a human-like smooth movement.

JP-A-11-215793 (page 4, FIGS. 1 to 4)

JP 2002-144274 A (page 3 to page 4, FIG. 1)

  Accordingly, an object of the present invention is to provide an artificial muscle which has a large amount of expansion and contraction, is excellent in responsiveness and motion stability, and is compact and has a high degree of freedom of motion.

  In order to solve the above-mentioned problem, the artificial muscle according to the present invention is characterized by comprising a linear motor in which both of two elements that perform relative linear motion have flexibility (claim 1). Here, the “linear motor” is a drive device that applies a force for causing a subject to perform a linear motion, and basically has a structure in which a cylindrical rotary motor is linearly developed.

  According to the above configuration, since the two elements perform relative linear motion by driving the linear motor, an expansion / contraction motion equivalent to that of a living muscle fiber can be obtained from the whole motor. Accordingly, by fixing the two elements to the two members, relative motion can be obtained between the two members. In this case, from the characteristics of the linear motor, a very large stroke, high responsiveness and operational stability can be obtained, and stroke adjustment is also possible. In addition, since the linear motor itself functions as a stretchable muscle fiber, it is advantageous in terms of space efficiency as compared with a case where the drive unit and the deformation unit are configured separately.

  In addition, since both of the two elements are flexible, the artificial muscle can be installed in a state of being deformed into an arbitrary non-linear shape. In this case, it can be installed in an arbitrary shape not only on a two-dimensional plane but also in a three-dimensional space, and a variety of operations that can be realized is possible. Therefore, it is possible to increase the degree of freedom of movement and realize a natural movement close to the movement of a human or the like with a single mechanism (claim 1).

  The flexibility of the linear motor can be provided by various methods. For example, flexibility of at least one of two elements is provided by a flexible material intermittently arranged in the relative movement direction of the two elements, or flexibility in which at least one flexibility is continuously arranged in the relative movement direction of the two elements. It is conceivable that it is provided by a sex material (claims 2 and 3). The former is suitable as a technique for imparting flexibility when a rigid body such as a permanent magnet is used as the field means, and the latter is used when a soft body such as a coil (coil) is used. Typical examples of the flexible material are resin and rubber.

  In general, linear motors are roughly classified into a planar type and a cylindrical type according to their shape. In the present invention, basically any type can be used. However, considering the ease of ensuring flexibility or the space efficiency when using multiple bundles as muscle bundles, either one of the two elements is used. It is preferable to use a cylindrical linear motor having a rod shape and a tube shape with the other arranged outside thereof. In addition to this, the cylindrical linear motor has the advantage that any element can be manufactured efficiently and at low cost by a known continuous molding method such as extrusion or drawing by using a resin or the like as a constituent material. Have.

  When this cylindrical linear motor is used, the outer element can be composed of, for example, a flexible cylindrical member and a coil arranged coaxially therewith (Claim 5). In this case, the outer element is used as the primary side (power supply side) of the linear motor, so that it is possible to prevent the wiring from the power source from interfering with the inner element that relatively slides. In addition, the coil can be arranged on the inner circumference as well as on the outer circumference of the cylindrical member, and can also be arranged so as to be embedded in the meat part of the cylindrical member.

  Further, the inner element can be constituted by, for example, a plurality of magnets and a flexible member interposed between the magnets. Here, “magnet” refers to one having a field pole, and not only permanent magnets but also electromagnets are included in “magnets”. However, when an electromagnet is used, it is preferable to use a permanent magnet in the sense that this measure is unnecessary because there is a possibility that the power supply wiring to the electromagnet may interfere with an outer element due to relative sliding movement.

  Since the linear motor is basically non-contact drive, contact friction does not occur between the two elements during relative movement of the two elements. However, when it is used as an artificial muscle as in the present invention, it may be required that the diameter dimension of each linear motor be a very small size (several tens of micrometers to several millimeters). There is a possibility of sliding friction between the two elements due to an expansion difference or the like. Even when the size is not small, if the artificial muscle is used in a bent or bent state, there is a possibility that the two elements come into contact with each other particularly at a portion having a large curvature. From this point of view, it is desirable to interpose a solid lubricating film between the two elements to reduce the contact friction between them. As the solid lubricating coating, any inorganic type such as molybdenum disulfide and organic type such as PTFE can be used.

  Considering each of the above linear motors as a single muscle fiber, and bundling these linear motors to form an artificial muscle bundle, it will be possible to obtain a greater stretch force, contributing to the expansion of the use of artificial muscles. Can do. In this case, the stretching force of the artificial muscle bundle can be easily controlled by adjusting the number of bundles.

  As described above, according to the artificial muscle according to the present invention, it is possible to provide a compact artificial muscle having a high speed response and a large amount of expansion and contraction and having a high degree of freedom of movement.

  Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 1 shows an example of an artificial muscle 1 according to the present invention, and illustrates a case where a cylindrical linear motor is used as a linear motor. This linear motor is mainly composed of a long tube-shaped first element 9 arranged on the outside and a long rod-shaped second element 10 inserted into the inner periphery of the first element 9. In a normal linear motor, one of the elements is formed extremely shorter than the other, but in the present invention, both elements 9 and 10 are formed to have substantially the same length.

  The tube-shaped first element 9 includes a cylindrical member 2 made of a flexible material such as resin or rubber, and a coil 3 formed coaxially with a constant pitch δ1 at a plurality of axial positions on the outer periphery thereof. Each coil 3 is connected by a connection wiring 6 and further connected to a power source 8 such as a three-phase alternating current via a control device 7. The first element 9 is formed, for example, by forming a cylindrical member 2 by continuous molding such as extrusion or drawing using the flexible material as a raw material, and forming the cylindrical member by a coil winding machine disposed at the outlet of the molding machine. The coil 3 and the connection wiring 6 are arranged on the outer periphery of the wire 2 and are further embedded in a cylindrical member 2 with a flexible thermoplastic resin and then cut into an appropriate length.

  The rod-shaped second element 10 includes a plurality of solid cylindrical permanent magnets 4 and a flexible member 5 which is also a solid cylindrical shape and is made of a flexible material such as resin. The permanent magnets 4 are arranged at an equal pitch δ2 in the axial direction with the magnetic poles aligned, and a flexible member 5 is interposed between the adjacent magnets 4. The second element 10 can be continuously formed, for example, by extruding or drawing a resin material constituting the flexible member 5. The magnet 4 and the flexible member 5 are firmly adhered and fixed so as not to be separated by a shearing force acting when the second element 10 is deformed, and preferably the entire magnet 4 and the flexible member 5 are flexible thermoplastic. They are integrated by means such as embedding with resin.

  When a current is supplied from the power supply 8, a moving magnetic field is generated on the first element 9 side by the action of each coil 3. A relative thrust is generated by the electromagnetic force generated between the moving magnetic field and the field pole of the second element 10, and the elements 9 and 10 slide relative to each other in the axial direction. As a result, the linear motor as a whole expands and contracts. . At this time, the control device 7 performs voltage / current control and frequency control based on the input signal to control the expansion / contraction speed, and further detects a relative position between the first element 9 and the second element 10 (illustrated). The relative positions of both elements 9 and 10 are managed based on the position information from (omitted).

  From the above configuration, if the opposite end portions 9a, 10a of both elements 9, 10 are attached to different members, both members can be moved relative to each other, and can be used as artificial muscles. In this case, from the characteristics of the linear motor, a large expansion / contraction stroke, high responsiveness / operation stability can be obtained, and stroke adjustment is also possible. In addition, since the linear motor itself functions as a muscle fiber, the entire configuration can be made compact and restrictions on the installation location can be reduced as compared with the case where the drive unit and the deforming unit have different structures.

  Further, since the linear motor is flexible, it can be used in a state of being deformed into an arbitrary non-linear shape. In this case, it can be installed in an arbitrary shape not only on a two-dimensional plane but also in a three-dimensional space, and a variety of realizable operations is possible. Accordingly, the degree of freedom of movement is increased, and a natural movement close to the movement of a human or the like can be realized with a single mechanism.

  In this configuration, the stretching force as the artificial muscle can be adjusted by changing the number of turns of the coil 3, the magnetic flux density of the magnet 4, or by changing the arrangement pitch δ 1 or δ 2 of the coil 3 or magnet 4. . Further, the arrangement pitches δ1 and δ2 are not necessarily equal pitches, and by setting them different in the axial direction, a non-linear relationship can be given between the stretching force and the power supply voltage (current). it can.

  Further, when the artificial muscle 1 needs to be greatly deformed and used, it is necessary to increase the flexibility of the linear motor. This is because the flexible material used in the first and second elements 9 and 10 is more flexible. This can be dealt with by changing to a soft one or by increasing the inter-coil pitch δ1 and the inter-magnet pitch δ2.

  The two elements 9 and 10 of the linear motor are basically in non-contact, but there are cases in which both elements 9 and 10 come into contact with each other at a greatly deformed portion or the like to cause contact friction. In order to reduce the contact friction at that time, it is desirable to interpose a solid lubricating film such as PTFE between the inner peripheral surface of the first element 9 and the outer peripheral surface of the second element 10. This film may be formed on both the inner peripheral surface of the first element 9 and the outer peripheral surface of the second element 10, or may be formed only on one of the surfaces.

  FIG. 2 shows an actual usage example of the artificial muscle 1, which is used as an assist device 12 for a person whose muscle strength has decreased. The assist device 12 is a device in which the artificial muscle 1 is disposed across a user's joint (a leg joint in the illustrated example), and the proximal end of the first element 9 is attached to the thigh 13a via a fixing member 14a. The tip of the second element 9 is attached to the shin part 13b via the fixing member 14b. When an input signal is given to the control device 7 based on a user's switch operation or a detection value of an appropriate sensor and a linear motor is driven, the leg 13 is bent and stretched at a joint portion, for example, when the user stands up from a chair or the like Alternatively, it is possible to obtain an assist effect when walking. Since this artificial muscle can be deformed three-dimensionally due to its flexibility to fit the shape of the leg 13, the user's uncomfortable feeling can be minimized. In this case, it is also possible to store the user's muscle strength data in the control device 7 in advance, calculate the optimum assist force based on this data, and drive the linear motor in accordance with the calculated value.

  In addition, by incorporating the artificial muscle into a prosthetic device such as a prosthetic limb or a prosthetic foot, it is possible to give the prosthetic device a movement according to the intention of the user. This artificial muscle can be used not only for the human body, but also for animals such as pets, and can also be used as a drive source for movable parts in robots and mannequins.

  In FIG. 2, the artificial muscle 1 is directly attached to the leg 13, but the artificial muscle 1 may be attached through clothes or by sewing into clothes.

  As described above, an example of the embodiment of the present invention has been described. For example, as shown in FIG. 3, the artificial muscle 1 shown in FIG. 1 is regarded as one muscle fiber, and a bundle of them is used as the artificial muscle bundle 1a. You can also. In this case, the resultant force of the stretching force generated in each artificial muscle 1 becomes the stretching force of the whole artificial muscle bundle 1a. Therefore, the necessary stretching force can be easily obtained by adjusting the number of bundles.

  In the above description, a case where a linear synchronous motor is used as the artificial muscle 1 is illustrated, but in addition to this, by forming the second element 10 on the secondary side with a flexible conductor, A linear induction motor that induces a current in the second element 10 with a moving magnetic field and generates a thrust between the induced current and the moving magnetic field can also be used. In addition, other linear motors such as a DC linear motor can be used. The form of the linear motor is not limited to the illustrated cylindrical type, and a planar type can also be used.

It is sectional drawing of the artificial muscle 1 concerning this invention. It is a front view of the assist apparatus 12 attached to a human leg joint. 1 is a perspective view of an artificial muscle bundle 1a formed by bundling artificial muscles 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Artificial muscle 1a Artificial muscle bundle 2 Cylindrical member 3 Coil 4 Magnet 5 Flexible member 7 Control apparatus 9 1st element 10 2nd element 12 Assist apparatus 13 Leg

Claims (8)

An artificial muscle consisting of a linear motor with both of the two elements that perform relative linear motions having flexibility. The artificial muscle according to claim 1, wherein the flexibility of at least one of the two elements is provided by a flexible material intermittently arranged in the relative movement direction of the two elements. The artificial muscle according to claim 1, wherein the flexibility of at least one of the two elements is provided by a flexible material continuously arranged in the relative movement direction of the two elements. 2. The artificial muscle according to claim 1, wherein the linear motor is a cylindrical linear motor in which one of the two elements is formed in a rod shape and the other is disposed on the outer periphery thereof. The artificial muscle according to claim 4, wherein the outer element has a flexible cylindrical member and a coil arranged coaxially therewith. The artificial muscle according to claim 4 or 5, wherein the inner element has a plurality of magnets and a flexible member interposed between the magnets. The artificial muscle according to claim 1 or 4, wherein a solid lubricating film is interposed between the two elements. An artificial muscle bundle configured by bundling a plurality of linear motors according to any one of claims 1 to 7.