JP2015113918A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator which is simple, easy and lightweight in structure, improved in maintain performance, and has contraction amount detection means.SOLUTION: In an actuator 40 in which a braid reinforcing fiber body 34 covering a pipe-shaped body as a whole is provided outside the pipe-shaped body, and the pipe-shaped body and both-end opening parts of the braid reinforcing fiber body 34 are sealed and joined to each other by a pair of end-part closing members, an annular elongation sensor 30 which detects a contraction amount corresponding to the contraction motion of the actuator is tightly arranged at the outside of the pipe-shaped body in a circumferential direction. Then, when the pipe-shaped body is expanded to a radial direction, a change of a resistance value of a sensor part 33 of the annular elongation sensor 30 which elongates following the expansion of the pipe-shaped body is derived as an output.

Description

  The present invention relates to a McKibben actuator (artificial muscle) that generates contraction by injecting a fluid, and more particularly to an actuator with a contraction amount detection function.

  The conventionally proposed McKibben artificial muscle is an artificial muscle that generates contractile force by supplying pressurized fluid (air) from its end, and is called Pneumatic Artificial Muscles (PAM). Alternatively, it is also called a pneumatic actuator (Pneumatic Actuator) because of its use as an actuator that generates contractile force by fluid injection.

  FIG. 9 schematically shows the external structure of a conventional artificial muscle actuator. 9 includes a tubular body 501, a braided reinforcing fiber body 503 disposed outside the tubular body 501, and an end closing member 505a for fixing the tubular body 501 and the braided reinforcing fiber body 503. , 505b. Rubber or rubber-like elastic material is used for the tubular body 501. In addition, various plastic materials can be used as long as they have the same elasticity as the tubular body 501 and can withstand pressure without leaking fluid to be injected. It may be replaced. The braided reinforcing fiber body 503 has a braided structure that reaches a stationary angle when the tubular body 501 has a maximum expanded diameter due to an increase in internal pressure. For example, an organic fiber such as an aromatic polyamide fiber, an ultrafine metal, or the like. Inorganic high-strength fibers such as wire strands can be used.

  The end closing members 505a and 505b hermetically seal the tubular body 501 from both sides in the axial (longitudinal) direction, and fix a braided reinforcing fiber body 503 that substantially generates tension, and a fluid injecting portion. 507 and the connection part 511a and 511b for transmitting a driving force are taken. Further, the tubular body 501 can be kept airtight, for example, a groove is formed on the outer periphery of each of the end closing members 505a and 505b, and the end of the tubular body 501 is used to press the end of the tubular body 501 using the groove. Fix in the way. The braided reinforcing fiber body 503 is fixed by the binds 509a and 509b, or fixed by means such as adhesion.

  The operation of the artificial muscle actuator shown in FIG. 9 will be briefly described. By introducing a pressurized fluid (air) into the internal cavity of the tubular body 501 from the injection part 507, the tubular body 501 expands in the diameter direction, and a braided reinforcing fiber body 503 formed around the tubular body 501 is formed. Deform in the radial direction. Since the fibers of the reinforcing fiber body of the braided reinforcing fiber body 503 arranged on the outside of the tubular body 501 are formed by knitting obliquely, the braided reinforcing fiber body 503 is deformed in the radial direction in the longitudinal direction. A large driving force is generated. Therefore, an operation for obtaining a desired force by injecting fluid by incorporating the artificial muscle into the link mechanism using the driving force at the time of contraction, for example, a wearable that is attached to a human body and assists the muscle strength. A device or the like can be realized.

  The McKibben actuator that operates with air in this way is lighter in weight compared to reciprocating actuators and servo motors using hydraulic cylinders, has no environmental pollution due to leakage of hydraulic oil, and is simple and lightweight. However, it has excellent features such as high output. On the other hand, however, there is a problem that it is difficult to grasp the amount of contraction as compared with other linear motion type cylinders and servo motors that can detect angles.

  In McKibben artificial muscles, a means to read the amount of contraction has been proposed, but when looking at the amount of contraction with fluid pressure, the point of balance of force is different between when there is no load and when there is a large load. Therefore, there is a problem that the contraction amount cannot be read correctly.

  For example, Patent Literature 1 discloses a fluid pressure actuator that includes a length sensor using a weak tension spring and a pressure sensor. Here, the length information and the pressure information are quickly fed back to the host computer by incorporating a sensor for each control board inside the actuator. In Patent Document 2, a technique for measuring the displacement of the tubular body in the longitudinal direction (the relative displacement amount of both closing members) by incorporating a light source and a light receiving element in the actuator and counting changes in the amount of light relative to the position displacement. Disclosure.

Japanese Patent No. 4310438 Japanese Patent Publication No. 7-054124

  However, in order to detect the length of an actuator etc. like patent document 1, putting a control circuit unit in every actuator will raise a cost greatly. Further, in Patent Document 1, since the length measuring spring is passed in the axial direction inside the actuator, the structure becomes complicated, and the problem of adjusting and fixing the tension of the spring also arises. There is a problem that the characteristics of the McKibben type artificial muscle that cannot be used.

  On the other hand, Patent Document 2 is difficult to manufacture even if there is an advantage that the measurement accuracy is improved by incorporating a measurement member such as a light receiving element (linearly) inside the actuator, resulting in high cost. Further, the configuration of Patent Document 2 has a structure that impairs the lightness that is the greatest advantage of the air bag type actuator and the flexibility that there is no problem even if it is bent in the lateral direction. In the worst case, when the actuator is bent by receiving a lateral force when it is extended (not operating), the displacement measurement portion inside the actuator may be damaged.

  As described above, in both Patent Documents 1 and 2, since the sensor is provided inside the tubular body of the actuator, even if the measurement accuracy can be improved, it is necessary to put the sensor peripheral portion into the airtight structure during manufacturing. In addition, there are problems that the structure and process including the handling of signal lines and power supply lines are complicated, and that maintenance is not performed for exchanging and adjusting the sensors.

  In addition, as in Patent Documents 1 and 2, when the sensor is attached in a direction parallel to the axis of the actuator, the amount of injected fluid or pressure that is an input and the amount of expansion and contraction that is an output are inversely proportional. In addition, when an elastic body such as a spring is used for the sensor, the sensor always receives the maximum load even when it is not in operation, and the spring or the like is in an extended state, so that long-term stability is maintained. Problems arise from the point of view.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an actuator including a contraction amount detection unit that has a simple structure, is simple and lightweight, and has improved maintainability. .

  As a means for achieving this object and solving the above-mentioned problems, for example, the following configuration is provided. That is, the present invention provides a braided reinforcing fiber body portion of organic or inorganic high-tensile fibers covering the entire tubular body portion outside the tubular body portion made of a rubber-like elastic material, and the tubular body. And the both ends of the braided reinforcing fiber body part are sealed and bonded with a pair of closing members, and fluid is injected into the tubular body part so that the tubular body part expands in the radial direction, An actuator for generating a tensile force in the axial direction by reducing a distance between a pair of closing members, and detecting a contraction amount corresponding to a contracting operation of the actuator due to a decrease in the distance between the pair of closing members. The sensor capable of taking out the predetermined output is closely arranged in the circumferential direction outside the tubular body portion.

  For example, the sensor extracts, as the predetermined output, a change in resistivity caused by deformation according to an external force applied by expansion of the tubular body portion in the radial direction as an electrical signal. Further, for example, the sensor includes a sensor unit whose resistivity changes due to deformation according to the external force, and an electrode unit for taking out the electrical signal, and the sensor unit is arranged in the circumferential direction of the actuator. It is attached over almost the entire circumference. In addition, for example, the sensor includes a sensor unit whose resistivity changes due to deformation according to the external force, an electrode unit for extracting the electrical signal, and a non-conductive unit that couples the sensor unit and the electrode unit. And the sensor portion is attached over substantially half of the circumferential direction of the actuator. Further, for example, the sensor section is formed by cutting a member made of an elastomer in which a conductive material is dispersed into a predetermined size.

  Furthermore, for example, the sensor extracts a change in resistivity due to deformation according to an external force applied by contraction in the longitudinal direction of the tubular body portion as the predetermined output as an electrical signal. In addition, for example, the sensor includes a sensor portion whose resistance value changes according to an applied load, and an electrode portion for taking out the change in the resistance value as an electrical signal, and the sensor portion includes the tubular body. On the outer surface of the part, the actuator is sandwiched between the non-extensible belt-like member attached over the entire circumference in the circumferential direction and the tubular body part.

  According to the present invention, the sensor unit is included in comparison with the method in which the detection means is installed in the longitudinal direction in which the actuator (artificial muscle) contracts by installing the contraction detection means in the circumferential direction of the actuator (artificial muscle). The material used for the entire sensor can be reduced, and the structure can be simplified to reduce costs and weight.

  In addition, when mounting the sensor in the circumferential direction of the actuator, the mounting position is not limited to the central portion of the actuator, for example, by selecting and mounting a portion close to the fixed portion (tube end portion) of the tubular body, Sensors with little displacement can also be used. Furthermore, the amount to be displaced can be adjusted by the mounting position.

It is a figure which shows the external appearance of the actuator (artificial muscle) which concerns on the embodiment of this invention. It is a figure which shows an example of the sensor which detects the amount of contraction corresponding to the contraction operation | movement of the actuator which concerns on this Example. It is a figure for demonstrating the detection operation | movement of the contraction amount in the actuator which concerns on Example 1 of this embodiment. It is a figure which shows the relationship between the contraction rate of the actuator in Example 1, and the resistance value of a cyclic | annular elongation sensor. It is a figure which shows the relationship between the contraction rate of the actuator in Example 1, and resistance value change of a cyclic | annular elongation sensor. It is a figure for demonstrating the detection operation | movement of the contraction amount in the actuator which concerns on Example 3 of this embodiment. It is a figure for demonstrating the contraction amount detection operation | movement of the actuator which concerns on Example 4 of this embodiment. It is a figure for demonstrating the contraction amount detection operation | movement of the actuator which concerns on Example 6 of this embodiment. It is a figure which shows typically the external appearance structure of the conventional artificial muscle actuator.

  Hereinafter, an embodiment according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows the appearance of an actuator (artificial muscle) according to this embodiment, and FIG. 2 shows an example of a sensor for detecting a contraction amount corresponding to the contraction operation of the actuator of FIG. Here, as will be described in detail in each of the following embodiments, the sensor 21 shown in FIG. 2 is brought into close contact with the outer circumference of the tubular body 1 of the actuator 10 shown in FIG. To detect the amount of contraction. More specifically, the sensor 21 that extracts an output corresponding to the contraction operation of the actuator 10 is disposed in close contact with the surface of the braided reinforcing fiber body 4 disposed outside the tubular body 1 of the actuator 10.

  As shown in FIG. 1, an actuator 10 according to this embodiment includes a braided reinforcing fiber body 3 that covers the entire tubular body 1 and hermetically seals and substantially generates tension, and a braided reinforcing fiber. A pair of end closing members 5a and 5b for fixing the body 3 are provided. Each of the end closing members 5a and 5b is provided with connecting portions 11a and 11b for transmitting a driving force to the outside, and a fluid injecting portion 18 is disposed on one end closing member.

  For the tubular body 1, for example, rubber or rubber-like elastic material is used, and various plastic materials can be used as long as they have the same elasticity and can withstand pressure without leaking fluid to be injected. What can be replaced is similar to the conventional actuator. The braided reinforcing fiber body 3 has a braided structure that reaches a stationary angle when the tubular body 1 has a maximum expansion diameter due to an increase in internal pressure. For example, an organic fiber such as an aromatic polyamide fiber or an ultrafine metal wire is used. Inorganic high-strength fibers such as stranded wires can be used.

  In the actuator according to the present embodiment, a method for fixing the end of the tubular body 1 to the end closing members 5a and 5b while maintaining the airtightness of the tubular body 1, and fixing the braided reinforcing fiber body 3 and the like. Since the method to do is the same as that of the conventional actuator, the description is omitted here.

  The sensor 21 shown in FIG. 2 is an elongation sensor that functions as a means for detecting a displacement amount corresponding to the contraction amount of the actuator. The sensor 21 is a sensor unit 23 formed by cutting a conductive rubber sheet (for example, conductive silicone rubber manufactured by Kyowa Kogyo Co., Ltd.) kneaded into rubber-like elastomer into a predetermined length and a predetermined width. And electrode portions 25a and 25b attached at opposite positions on both ends of the sensor portion 23. The width and length of the sensor unit 23 can be appropriately determined depending on the specific resistance of the conductive rubber sheet to be used, the output to be taken out, the position to be used, and the like.

Next, various examples of the actuator according to the embodiment of the present invention will be specifically described.
<Example 1>
FIG. 3 is a diagram for explaining a contraction amount detection operation in the actuator (artificial muscle) according to Example 1 of the present embodiment. FIG. 3A shows a state where the sensor (annular elongation sensor) 30 used in the first embodiment is attached when the actuator 40 is not contracted. Here, as shown in FIG. 3A, the annular stretch sensor 30 is attached over the entire circumference of the actuator 40 in the circumferential direction.

  FIG. 3B is a detailed enlarged view of a portion A in FIG. 3A, and shows the appearance of the annular stretch sensor 30 when not contracted. The annular stretch sensor 30 is made of, for example, a stretchable conductive silicone rubber cut out to have a length of about 10 cm and a width of about 1.5 cm to form a sensor portion 33, and electrode portions 35 a, 35b is attached, and the ends of the electrode portions 35a and 35b that are not attached with conductive rubber are connected by a non-extensible member.

  In addition, by making the outer periphery dimension of the annular stretch sensor 30 slightly smaller than the outer periphery dimension of the actuator 40 at the time of non-shrinkage, the annular stretch sensor 30 itself can be attached to the actuator 40 using the contractibility. In order to prevent displacement, the electrode portions 35a and 35b of the annular stretch sensor 30 are formed by braided reinforcing fiber bodies 34 (parts shown with a lattice pattern in FIG. 3) covering the entire tubular body of the actuator 40. ) May be fixed by bonding or the like. Furthermore, the sensor unit 33 of the annular stretch sensor 30 may be provided with a mechanism that can be attached and detached so as to be easily removed.

  When a fluid is injected into the tubular body of the actuator 40 according to the first embodiment, the tubular body expands in the diameter direction as shown in FIG. The sensor portion 33 of the annular elongation sensor 30 adhered in the outer peripheral direction of the braided reinforcing fiber body 34 shown with a lattice pattern in a) also extends following the expansion of the tubular body. The state of the annular stretch sensor 30 at that time is shown in FIG. 3D, which is a detailed enlarged view of a portion B in FIG. As shown in FIG. 3D, the resistance value changes as the sensor unit 33 extends, and the resistance value of the sensor unit 33 of the annular extension sensor 30 changes via the lead wire 37 connected to the electrode units 35a and 35b. Can be extracted as output.

  In addition, the attachment position in the circumferential direction of the annular elongation sensor 30 in the actuator 40 is not necessarily limited to the central portion of the actuator 40. For example, a portion close to the fixing portion (tube end portion) of the tubular body is selected and attached. May be. By doing so, a sensor with a small amount of displacement (that is, not stretched so much) can be used as the annular stretch sensor 30. Further, the amount of displacement at the attachment position can be adjusted.

  FIG. 4 shows the relationship between the contraction rate of the actuator and the resistance value of the annular elongation sensor in the first embodiment. As shown in FIG. 4, the relationship between the contraction rate of the actuator and the reciprocal of the resistance value (1 / resistance value) of the sensor portion 33 of the annular elongation sensor 30 is practical even if it is approximated by the first order in the range of use of the actuator. It is understood that there is no problem.

  FIG. 5 shows the relationship between the contraction rate of the actuator and the change in resistance value of the annular elongation sensor in the first embodiment. As is apparent from FIG. 5, a proportional relationship is recognized between the contraction rate in the longitudinal direction of the actuator and the resistance value change ΔR of the annular elongation sensor. From this, it can be seen that the contraction amount of the actuator can be measured by the change in the resistance value of the annular elongation sensor.

  According to FIG. 5, the contraction rate in the length direction of the actuator and the resistance value change amount of the annular elongation sensor are slightly shifted due to the difference in load, but such a deviation is caused by a balance point with the pressure. Since it is a principle of shifting, it can be corrected, and no particular problem occurs in detecting the contraction amount of the actuator. Further, when the actuator contracted and expanded several times, the repetition error was about 5%.

<Example 2>
In Example 2 of the present embodiment, the stretchable conductive silicone rubber is cut out so that, for example, the length is about 5 cm and the width is 1.5 cm, and this is used as a sensor portion, and both ends in the longitudinal direction are used. Prepare an electrode with an electrode attached. Here, although not shown in the figure, the end portions of the electrode portion not attached with the conductive rubber are connected by another non-conductive elastomer member having extensibility to create an annular stretch sensor.

  In the first embodiment, the sensor unit of the annular stretch sensor is brought into close contact with almost the entire circumference of the tubular body of the actuator. However, in the second embodiment, 1/2 of the circumferential direction of the tubular body of the actuator is used. The sensor part is closely contacted to the extent, and a stretchable elastomer is arranged in the remaining part in the circumferential direction. Thus, in Example 2, the sensor member used for a sensor can be reduced by replacing a part of electroconductive silicone rubber which comprises a sensor with the elastomer which has the same elasticity as it.

  Also with the annular elongation sensor of Example 2 having such a configuration, the contraction rate of the actuator and the change in resistance value of the annular elongation sensor have the same relationship as in Example 1.

<Example 3>
FIG. 6 is a diagram for explaining a contraction amount detection operation in the actuator (artificial muscle) according to Example 3 of the present embodiment. FIG. 6A shows a state where the annular elongation sensor 70 used in the third embodiment is attached when the actuator 40 is not contracted. Here, the entire circumference of the actuator 40 in the circumferential direction is shown. An annular stretch sensor 70 is attached.

  FIG. 6B is a detailed enlarged view of a portion C in FIG. 6A, and shows the appearance of the annular elongation sensor 70 when not contracted. The annular elongation sensor 70 of Example 3 is obtained by cutting a stretchable conductive silicone rubber so as to have a length of about 5 cm and a width of 1.5 cm, for example, as a sensor unit 73, and electrodes on both ends in the longitudinal direction. The portions 75a and 75b are attached, and the ends of the electrode portions 75a and 75b that are not attached with conductive rubber are connected to each other by a non-extensible and non-conductive member.

  As with the annular elongation sensor according to the first embodiment, the outer circumferential dimension of the annular elongation sensor 70 according to the third embodiment is made slightly smaller than the outer circumferential dimension of the actuator 40 before the contraction, so Ensuring adhesion to braided reinforcing fiber body.

  In Example 3, when fluid is injected into the tubular body of the actuator 40, the tubular body expands in the diametrical direction as shown in FIG. At this time, the sensor part 73 of the annular stretch sensor 70 closely attached in the outer peripheral direction of the braided reinforcing fiber body arranged on the tubular body of the actuator 40 is also a detailed enlarged view of the D part in FIG. As shown in (d), the tube body expands following the expansion of the tubular body.

  However, in the annular elongation sensor 70 of the third embodiment, the portions other than the sensor portion 73 are non-extensible and non-conductive members (for example, non-conductive members) of the electrode portions 75a and 75b without the conductive rubber. Therefore, when the actuator 40 is contracted, only the sensor unit 73 is extended. As a result, at the time of detecting the contraction amount of the actuator 40, as shown in FIG. 6C, the constriction 41 is generated in the circumferential portion where the annular elongation sensor 70 of the actuator 40 is in close contact due to the expansion of the tubular body in the diameter direction. For this reason, the annular elongation sensor 70 is more firmly tightened to the tubular body, and the adhesion of the sensor can be ensured.

  As described above, the third embodiment uses the annular stretch sensor 70 having a configuration in which the sensor portion is in close contact with about 1/2 of the circumferential direction of the actuator and the remaining portion in the circumferential direction is a non-stretchable portion. . Even in this case, as in the second embodiment, the number of sensor members (conductive silicone rubber) constituting the annular elongation sensor 70 can be reduced, and the adhesion of the annular elongation sensor 70 to the tubular body can be improved.

  In the annular elongation sensor 70 according to the third embodiment, the change in the resistance value of the sensor portion 73 of the annular elongation sensor 70 is taken out as an output via the lead wire 77 connected to the electrode portions 75a and 75b. Since the relationship between the shrinkage rate and the change in resistance value of the annular elongation sensor is the same as that in the first embodiment, the description thereof is omitted.

<Example 4>
FIG. 7 is a diagram for explaining the contraction amount detection operation of the actuator (artificial muscle) according to Example 4 of the present embodiment. Here, as shown in FIG. 7, the stretch sensor 90 is attached to a part of the entire circumference of the actuator 40. Therefore, the elongation sensor 90 is obtained by cutting a stretchable conductive silicone rubber into a predetermined size as a sensor portion 93, and an electrode portion 95a is provided at one end of the sensor portion 93 and an electrode portion 95b is provided at the other end. The configuration is as follows. Then, a lead wire 97 is connected to these electrode portions 95a and 95b in order to take out a change in resistance value of the sensor portion 93 of the stretch sensor 90 as an output.

  In Example 4, the electrode portions 95a and 95b of the stretch sensor 90 are directly fixed to the braided reinforcing fiber body 94 (the portion shown with a lattice pattern in FIG. 7) on the surface of the actuator 40 by adhesion. Therefore, when a fluid is injected into the tubular body of the actuator 40 according to the fourth embodiment, as shown in FIG. 7B, the electrode bonded and fixed to the braided reinforcing fiber body 94 due to the expansion of the tubular body in the diameter direction. The parts 95a and 95b move in directions away from each other. As a result, the sensor portion 93 disposed between the electrode portions 95a and 95b extends in the circumferential direction of the tubular body of the actuator 40.

  As described above, in the fourth embodiment, the extension sensor 90 is configured as described above, so that the extension sensor 90 can be reduced in size, and thus can be attached to a part of the outer surface of the tubular body of the actuator. A relationship between the contraction rate of the actuator and the change in resistance value of the elongation sensor can be obtained with a simple configuration.

<Example 5>
In Example 5 of the present embodiment, a sensor is attached over the entire circumference of the actuator (artificial muscle) in the same manner as in Example 1 and the like, but the sensor portion of the sensor is not conductive silicone rubber. The tension sensor uses a sensor member whose resistance value changes depending on the tension. With such a configuration, even if the expansion in the circumferential direction (radial direction) of the tubular body of the actuator is somewhat hindered and the contraction amount of the actuator may be reduced, the operation of the actuator itself is not affected.

  That is, in Example 5, by using the tension sensor, an output shift in the repetitive operation of the actuator is suppressed, and highly accurate measurement is possible. In addition, the diameter of the sensor with respect to tension can be made smaller than the diameter of the actuator at the time of non-shrinkage, and it can attach using self contractibility. In addition, when a stronger fixation to the actuator is required, the electrode portion may be directly fixed to the braided reinforcing fiber body on the actuator surface by adhesion or the like.

  Even if a tension sensor using a sensor member whose resistance value changes depending on the tension as in the fifth embodiment, the same relationship as in the first embodiment is obtained with respect to the contraction rate of the actuator and the change in the resistance value of the tension sensor. It is done.

<Example 6>
FIG. 8 is a diagram for explaining the contraction amount detection operation of the actuator (artificial muscle) according to Example 6 of the present embodiment. In the sixth embodiment, a contraction sensor is used to detect the contraction amount of the actuator, and the contraction rate of the actuator is detected from a change in the resistance value of the contraction sensor. Therefore, for example, as shown in FIG. 8 (a), a stretchable conductive silicone rubber portion cut to a predetermined size is used as a sensor portion 103, and electrode portions 105a, A contraction sensor 100 to which 105b is attached is prepared. Then, the contraction sensor 100 is fixed to the lower portion of the belt 111 attached over the entire circumference of the actuator 40. That is, in Example 6, the shrinkage sensor 100 is fixed in a state of being sandwiched between the braided reinforcing fiber body 104 (portion marked with the lattice pattern in FIG. 8) on the tubular body of the actuator 40 and the belt 111. .

  When fluid is injected into the tubular body of the actuator 40 according to the sixth embodiment, the tubular body expands in the diameter direction as shown in FIG. 8B, and the braided reinforcing fiber body 104 contracts in the longitudinal direction. On the other hand, since the belt 111 is made of a non-extensible material, the tubular body of the belt 111 portion expands while forming the recess 101, and the diameter at the time of non-shrinkage is maintained in that portion.

  In Example 6, when the actuator 40 expands in the diameter direction of the tubular body, the sensor unit 103 of the contraction sensor 100 sandwiched between the tubular body (more specifically, the braided reinforcing fiber body 104) and the belt 111 is also provided. The actuator 40 contracts in the longitudinal direction. Then, a change in resistance value of the sensor unit 103 of the contraction sensor 100 is taken out as an output via the lead wire 107 connected to the electrode units 105a and 105b.

  In FIG. 8, the electrode portions 105a and 105b are taken out in the length direction of the sensor 100. However, the electrode portions are appropriately formed in the thickness direction by attaching metal foil or attaching a conductive tape. May be. Further, the sensor unit is not limited to the conductive rubber system, and is resisted by a compression pressure (load) generated between the tubular body (braided reinforcing fiber body 104) and the belt 111 due to expansion of the tubular body in the diameter direction. Piezoelectric sensors that vary in value can also be used.

  As described above, the actuator according to the present embodiment uses the extension sensor made of a flexible conductive elastomer as a sensor for detecting the contraction amount of the actuator, so that the actuator as the artificial muscle has the flexibility. There is no loss of sex. In addition, by adopting a configuration in which the sensor is attached in the peripheral direction outside the artificial muscle actuator, the sensor structure can be extremely simplified, the weight can be reduced simply and lightly, and maintenance such as replacement and adjustment is improved.

  In addition, the actuator according to the present embodiment is applied with a load according to the contraction amount of the actuator according to the structure described above, and the resistance value of the sensor unit changes accordingly. It is possible to realize the original movement of the sensor in which no load is applied during expansion (relaxation), and an output proportional to the contraction amount can be extracted from the contraction amount of the actuator and the reciprocal of the resistance value obtained from the sensor.

  Furthermore, because the sensor is placed in close contact with the outer periphery of the actuator and the sensor itself is small, it does not occupy a large volume even if the sensor is mounted outside the actuator and should be handled in the same way as an actuator without a sensor. Can do.

  In addition, since the artificial muscle is squeezed small during non-operation without fluid injection, it is assumed that the actuator bends depending on the usage, but even in that case, the sensor is placed in the circumferential direction outside the actuator and the length of the artificial muscle is Since there is no movable part that passes the shaft in the direction, it is not affected by the bending of the actuator.

  Furthermore, in flexible rubber-based sensors, it is conceivable that plastic deformation increases from elastic deformation due to repeated deformation, and the output value shifts, but in artificial muscle actuators, it is used for repeated contraction and is long at the same position. There is almost no time holding. Therefore, the shift of the output value can be avoided by performing zero point alignment (origin alignment) when there is no load. In addition, since the sensor can be attached to the outside of the artificial muscle, there is an advantage in terms of maintenance that the sensor whose numerical value is out of the reference range in the measurement under no load can be easily replaced.

DESCRIPTION OF SYMBOLS 1 Tubular body 4,34,94,104 Braided reinforcement fiber body 5a, 5b End part closing member 10,40 Actuator 11a, 11b Connection part 18 Injection | pouring part 21 Sensor 23, 33, 73, 93, 103 Sensor part 25a, 25b 35a, 35b75a, 75b, 95a, 95b, 105a, 105b Electrode part 30, 70 Annular elongation sensor 37, 77, 97, 107 Lead wire 90 Elongation sensor 100 Contraction sensor 111 Belt

Claims (7)

A braided reinforcing fiber body portion of organic or inorganic high-tensile fibers covering the entire tubular body portion is disposed outside the tubular body portion made of a rubber-like elastic material, and the tubular body portion and the braided reinforcement By sealing and joining the opening portions at both ends of the fiber body portion with a pair of closing members and injecting a fluid into the tubular body portion, the tubular body portion expands in the radial direction, and between the pair of closing members An actuator that generates a tensile force in the axial direction by reducing the distance,
A sensor capable of taking out a predetermined output for detecting a contraction amount corresponding to the contraction operation of the actuator due to a decrease in the distance between the pair of closing members is closely arranged in the circumferential direction outside the tubular body portion An actuator characterized by that. 2. The sensor according to claim 1, wherein the sensor extracts, as the predetermined output, an electrical signal as a change in resistivity caused by deformation according to an external force applied by expansion of the tubular body portion in a radial direction. The actuator described. The sensor includes a sensor portion whose resistivity changes due to deformation according to the external force, and an electrode portion for taking out the electrical signal, and the sensor portion is disposed on substantially the entire circumference of the actuator in the circumferential direction. The actuator according to claim 2, wherein the actuator is mounted across. The sensor includes a sensor unit whose resistivity changes due to deformation according to the external force, an electrode unit for extracting the electrical signal, and a non-conductive connection unit that couples the sensor unit and the electrode unit. The actuator according to claim 2, wherein the sensor unit is attached over approximately half of the circumferential direction of the actuator. The actuator according to claim 3 or 4, wherein the sensor unit is formed by cutting a member made of an elastomer in which a conductive material is dispersed into a predetermined size. 2. The sensor according to claim 1, wherein the sensor extracts, as the predetermined output, an electrical signal as a change in resistivity caused by deformation according to an external force applied by contraction in a longitudinal direction of the tubular body portion. Actuator. The sensor includes a sensor portion whose resistance value changes according to an applied load, and an electrode portion for taking out the change in the resistance value as an electrical signal, and the sensor portion is on an outer surface of the tubular body portion. 2. The actuator according to claim 1, wherein the actuator is sandwiched between a non-extensible belt-like member attached over the entire circumference of the actuator in the circumferential direction and the tubular body portion.