Soft actuator system

Abstract

To provide a soft actuator system capable of converting local telescopic motion of a fluid pressure type soft actuator including a pneumatic pressure type, into non-linear motion.SOLUTION: A soft actuator system comprises: a soft actuator 110 having a fluid chamber 112 capable of storing working fluid therein and expanding and contracting due to the pressure of the working fluid; a connection adjustment member 120 attached to the soft actuator 110 and made of a material having higher rigidity than the soft actuator 110; and a restriction member 160 that connects the connection adjustment members 120 of the soft actuator 110 having a plurality of connection adjustment members 120 together, and restricts mutual movement of the connected connection adjustment members 120.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a pneumatic soft actuator system used in robot fingers, robot arms, rehabilitation equipment, etc., and more particularly to a soft actuator system that converts the expansion and contraction motion of a soft actuator into non-linear motion. [Background technology]

[0002] Pneumatic soft actuators are made of flexible materials such as silicone, and perform movements such as stretching and bending when air pressure is applied. Structures and mechanisms have been devised to realize any movement (stretching, bending, twisting, etc.) of pneumatic soft actuators, and these structures and mechanisms are major factors that determine the movement of pneumatic soft actuators.

[0003] Conventional pneumatic soft actuators have been reported that are made of flexible materials (such as silicone) and have a structure and mechanism for fulfilling the actuator's operating functions. For example, (1) a structure that uses a sheet and wire (see Patent Document 1), (2) a structure that uses a non-stretchable sheet such as paper (see Patent Document 2), (3) a structure that uses a wire (see Patent Document 3), and (4) a structure that uses a wire (see Patent Document 4).

[0004] Furthermore, a technology has been disclosed for an air-containing fluid actuator that has a plurality of chambers made of a flexible material and has an internal gas chamber, a conductive structure that connects one end of each chamber to conduct gas to the connecting part, and a plurality of hinge structures that use the gas conductive part between the chambers as a fulcrum to relatively displace the orientation of adjacent chambers that are in contact with each other as each chamber expands and contracts, thereby bending the overall shape of the structure made up of the plurality of chambers, and that bends and extends as the gas pressure increases and decreases (see Patent Documents 5, 6, and 7). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US2016 / 0252110A1 [Patent Document 2] US2015 / 0266186A1 [Patent Document 3] JP 2009-121658 A [Patent Document 4] JP 2019-503278 A [Patent Document 5] Special Publication No. 2018-512304 [Patent Document 6] JP 2014-020462 A [Patent Document 7] JP 2003-184819 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the techniques disclosed in Patent Documents 1 to 4, a structure or mechanism that determines the initial shape and motion direction of the pneumatic soft actuator is built into the pneumatic soft actuator, which makes it difficult to significantly adjust the pneumatic soft actuator, and may limit the room for customization and applications.

[0007] Moreover, the techniques disclosed in Patent Documents 5 to 7 bend the entire shape of a long soft actuator, making it difficult to locally bend or expand or contract a part of the actuator.

[0008] The purpose of using actuators in robot fingers, robot arms, and rehabilitation equipment is to freely control the force, speed, angle, etc. applied when moving at a specified location. However, the technologies disclosed in Patent Documents 1 to 7 require complex mechanisms and fluid pressure actuators including multiple pneumatic methods in order to achieve these required movements, which increases the possibility of failure and may increase the complexity of manufacturing, assembly, and adjustment work.

[0009] The present invention has been made in consideration of the above-mentioned circumstances, and provides a soft actuator system that converts the localized expansion and contraction motion of a fluid pressure soft actuator, including a pneumatic type, into non-linear motion without incorporating any mechanism from the beginning. The present invention can provide a structure that makes it possible to adjust the initial shape, operating direction, and bending point of the soft actuator. [Means for solving the problem]

[0010] One aspect of the present invention is a soft actuator system comprising: a soft actuator having a fluid chamber capable of storing a working fluid therein and expanding and contracting due to the pressure of the working fluid; a connection adjustment member attached to the soft actuator and made of a material having higher rigidity than the soft actuator; and a regulating member that connects the connection adjustment members of the soft actuator having multiple connection adjustment members and regulates the mutual movement of the connected connection adjustment members.

[0011] According to this configuration, by connecting the soft actuators with multiple connection adjustment members and providing a restricting member that restricts the mutual movement of the connected connection adjustment members, it is possible to realize the intended initial shape without incorporating mechanisms from the beginning. Furthermore, the restricting member that connects the multiple connection adjustment members can restrict the movement direction when the soft actuator expands and contracts due to fluid pressure, and adjust the amount of movement.

[0012] This configuration can realize the same functions as mechanical actuators using servo motors, etc., in terms of the initial shape, direction of movement, and amount of movement required for an actuator in a robot finger, robot arm, or rehabilitation device. This configuration also makes it possible to enjoy the advantages of soft actuators, such as shape adaptability, flexibility, stretchability, light weight, low cost, easy availability of materials, stability even in the atmosphere, and no operating noise. Furthermore, it is possible to realize stable operation that prevents sudden load increases and runaway due to electrical problems, etc.

[0013] Furthermore, with this configuration, in the past, in order to make a robot finger or the like perform complex and precise movements, it was necessary to arrange a considerable number of soft actuators such as artificial muscles, or to push and pull a considerable number of wires, etc., but with this configuration, the number of actuators to be arranged can be reduced and the amount of control can also be reduced, resulting in an inexpensive control system with improved reliability.

[0014] The soft actuator of the present invention may be made of an elastomer material such as rubber, or a plastic material arranged in an accordion-like structure, or a relatively soft material, which expands, contracts, and bends under pressure, or a so-called artificial muscle. There are no particular limitations on the method for manufacturing the soft actuator, and for example, an elastomer material may be molded. The fluid for applying pressure to the soft actuator may be selected from gases such as air and liquids such as water, depending on the application.

[0015] In the above configuration, the fluid chambers of adjacent soft actuators can be configured to communicate with each other.

[0016] In this configuration, by communicating the fluid chambers, it is possible to control the actuators that are connected to each other so as to simultaneously pressurize and energize them, thereby making it possible to reduce the amount of control.

[0017] With this configuration, depending on the size and operating form of the parts required to control the soft actuator system, for example, a soft actuator with an accordion-like structure having multiple pressure chambers that are connected to each other, or artificial muscles can be used in a state connected in series or parallel.

[0018] In the above configuration, the regulating member can be formed with a plurality of holes aligned along the connection direction, and the connection adjustment member can be formed with pins that are inserted into the holes, and the pins can be rotated within the holes to regulate the rotational direction of the connection adjustment member.

[0019] In this configuration, the pin inserted into the hole formed in the restricting member allows the connection adjustment member to rotate in any direction relative to the restricting member. Here, the hole may be a circular hole, an elliptical hole, or a rectangular hole, and may be selected so as to restrict the rotation of the connection adjustment member according to the design. In addition, the drilling direction of the hole may be an oblique hole formed with respect to the soft actuator, or the soft actuator may be initially twisted, in order to realize the intended initial state of the soft actuator system.

[0020] In the above-mentioned configuration, a predetermined gap may be formed between the pin inserted into the hole and the inner edge of the hole.

[0021] According to this configuration, a predetermined gap is provided between the pin and the inner edge of the hole, allowing the connection adjustment member to move freely relative to the regulating member, thereby enabling the range of motion of, for example, a robot finger to be expanded as desired.

[0022] In the above-mentioned configuration, the regulating member may be made of an elastic material having a higher rigidity than the soft actuator.

[0023] According to this configuration, the elasticity of the restricting member itself makes it easy for the soft actuator system to return to its initial state after performing an action such as bending. Effect of the Invention

[0024] The present invention provides a soft actuator system that converts the localized expansion and contraction motion of a fluid pressure soft actuator, including a pneumatic type, into a non-linear motion. The present invention also provides a structure that allows adjustment of the initial shape, operating direction, and bending point of the soft actuator without incorporating any mechanism from the beginning. [Brief description of the drawings]

[0025] [Figure 1] 1 shows a component that is a fundamental technology relating to a first embodiment of the present invention. [Diagram 2] 1A to 1C are diagrams illustrating the structure and function of a soft actuator system according to a first embodiment of the present invention. [Diagram 3] FIG. 11 is an overall schematic diagram of a soft actuator system according to a second embodiment of the present invention. [Figure 4] 13 is an operation example of the soft actuator system according to the second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] <Description of the First Embodiment> A first embodiment of the present invention will be described below with reference to FIGS. Fig. 1 shows components that are elemental technologies according to the first embodiment of the present invention, and Fig. 2 is a diagram illustrating the structure and function of the soft actuator system according to the first embodiment of the present invention. In the following description, configurations denoted with the same reference numerals in different drawings are assumed to be similar, and descriptions thereof may be omitted.

[0027] The soft actuator system of the present invention may be of any configuration as long as it comprises a soft actuator having a fluid chamber capable of storing a working fluid therein and expanding and contracting due to the pressure of the working fluid, a connection adjustment member attached to the soft actuator and made of a material with higher rigidity than the soft actuator, and a regulating member that connects the connection adjustment members of a soft actuator having multiple connection adjustment members and regulates the mutual movement of the connected connection adjustment members.

[0028] FIG. 1 shows elemental technologies constituting the soft actuator system according to this embodiment, and FIG. 2 shows the overall configuration and operation of the soft actuator system assembled from these elemental technologies.

[0029] Fig. 1(A) shows a conceptual diagram of a typical soft actuator. A soft actuator is a material, element, or device that functions as an actuator by deformation of a lightweight, flexible material. Soft actuator 110 has fluid chamber 112 capable of storing working fluid Air inside container 114 made of an elastic material, and expands and contracts in the direction of the arrow due to the pressure of the working fluid Air.

[0030] 1(A), container 114 expands and contracts in the direction of the arrow by injecting and discharging air, which is a working fluid, from the top of fluid chamber 112. The direction of expansion and contraction can be set by changing the thickness of the wall of container 114 or by wrapping a highly rigid material in a direction perpendicular to the expansion and contraction direction, as with McKibben artificial muscle.

[0031] The material of the container 114 can be selected appropriately according to the application from an elastomer material such as rubber, a plastic material arranged in an accordion-like structure or a so-called artificial muscle that expands, contracts, and bends under pressure, or a relatively soft material. There is no particular limitation on the method of manufacturing the soft actuator, and for example, an elastomer material can be molded. The fluid for applying pressure to the soft actuator can be selected appropriately from a gas such as air, or a liquid such as water.

[0032] FIG. 1(B) shows an example of the connection adjustment member 120, which is attached to the soft actuator 110 as shown in FIG. 2. The attachment may be mechanical attachment or adhesion, and is not particularly limited. The connection adjustment member 120 in this embodiment is applied with a form similar to a hinge. That is, one hinge tube 124 is formed at approximately the center of one side (left side of FIG. 1(B)) of a plate-like mounting plate 128 having higher rigidity than the soft actuator 110, and hinge tubes 126, 126 are formed on the upper end side and the lower end side of the other side (right side of FIG. 1(B)). The hinge tubes 126, 126 are arranged so that the hinge tube 124 fits between the upper and lower hinge tubes 126, 126. The hinge tubes 124, 126 are formed in a tubular shape with a hole 122 in the center, and the pin 150 of FIG. 1(C) is inserted through the hinge tubes 124, 126.

[0033] The material of the connection adjustment member 120 is not particularly limited as long as it has a higher rigidity than the soft actuator 110, and can be selected from metals, resins, and the like.

[0034] 2, the soft actuator 110, the connection adjustment members 120 attached to the soft actuator 110, and the hinge tubes 124 and 126 of adjacent connection adjustment members 120 are fitted into each other so as to communicate with their respective holes 122. A pin 150 is inserted into this hole 122 and positioned so that an end of the pin 150 protrudes, connecting the connection adjustment members 120 (120a, 120b, 120c, 120d) of the soft actuators 110 (110a, 110b, 110c, 110d) to each other.

[0035] The restricting members 160, 170 in this embodiment are long thin plates, and are formed with a plurality of holes 162, 164, 172, 174 aligned in the connecting direction of the connection adjustment member 120, and the pins 150 are inserted through these holes 162, 164, 172, 174. In this manner, the soft actuator system 100 is constructed by assembling the soft actuator 110, the connection adjustment member 120, the pin 150, and the regulating members 160 and 170, which are elemental technologies.

[0036] The functions of the regulating members 160 and 170 will be described below in order. Here, as an example, hole 162 of restriction member 160 is a circular hole, hole 164 is an elongated hole, and hole 172 of restriction member 179 is an elongated hole, and hole 174 is a circular hole, but the shapes of the holes are not limited to these. For example, if the opening of the hole is set large relative to the pin, soft actuator system 100 can increase the range of oscillation relative to the linear state and can also suppress stress concentration on soft actuator 110.

[0037] When pin 150 is inserted through holes 162 and 164 of regulating member 160, the positional relationship between connection adjustment members 120a, 120b, and 120c is fixed. When working fluid is injected into fluid chambers 112 of soft actuators 110a, 110b, and 110c and the pressure in fluid chambers 112 rises, soft actuators 110a, 110b, and 110c attempt to extend in the direction of arrow L. However, their movement is restricted by connection adjustment members 120a, 120b, and 120c to which regulating member 160 is attached.

[0038] Soft actuator 110a rotates and bends towards the front in FIG. 2 due to pin 150 connection with connection adjustment members 120a, 120b. Soft actuator 110b cannot rotate and bend like soft actuator 110a due to restrictions imposed by pin 150 connection with connection adjustment members 120a, 120b and connection adjustment members 120b, 120c, and by regulating member 160. However, soft actuator 110b can extend in the direction of arrow L by the length of hole 164, which is an elongated hole extending in the extension / contraction direction. Soft actuator 110c operates in the same manner as soft actuator 110b.

[0039] Next, when the pin 150 is inserted through the holes 172 and 174 of the restricting member 170, the positional relationship between the connection adjustment members 120b, 120c, and 120d is fixed. Unlike the restricting member 160, the restricting member 170 has a bent shape centered on the hole 174 formed in the center, which determines the initial state. When the working fluid is injected into the fluid chamber 112 of the soft actuators 110b, 110c, and 110d and the pressure in the fluid chamber 112 rises, the soft actuators 110b and 110c try to extend in the direction of the arrow L, and the soft actuator 110d tries to extend in the direction of the arrow S. However, their movements are restricted by the connection adjustment members 120b, 120c, and 120d to which the restricting member 160 is attached.

[0040] Soft actuator 110b rotates and bends toward the front in FIG. 2 due to pin 150 connection with connection adjustment members 120b, 120c. Soft actuator 110c cannot bend like soft actuator 110b due to restrictions imposed by regulating member 170 and pin 150 connection with connection adjustment members 120b, 120c and connection adjustment members 120c, 120d. However, soft actuator 110c extends in the direction of arrow L by the length of hole 172, which is an elongated hole extending in the extension / contraction direction. Soft actuator 110d extends linearly in the direction of arrow S of bent regulating member 170.

[0041] In this manner, by rotating the connection adjustment member 120 and the pin 150 inserted into the holes 122, 162, 164, 172, 174 of the regulating members 160, 170, the rotation direction and operating direction of the connection adjustment member 120 can be regulated and the initial state of the soft actuator system 100 can be determined.

[0042] In this embodiment, a circular hole and an elongated hole are described as examples of the shape of the hole, but the shape is not limited to these. In addition, by providing a predetermined gap between the pin inserted into the hole and the inner edge of the hole, the connection adjustment member can move freely relative to the restricting member, and the movable range of, for example, a robot finger can be arbitrarily expanded.

[0043] Furthermore, by using a restricting member formed in a predetermined shape, such as a bent shape, like the restricting member 170, it is possible to give the soft actuator system 100 an arbitrary initial shape. Furthermore, it is also possible to change the allowable amount of expansion and contraction movement of soft actuator 110 by appropriately selecting the materials of connection adjustment member 120 and regulating members 160 and 170. For example, by using an elastic material for regulating member 170, when soft actuator 110 is pressurized, the bent portion in the direction of arrow S will stretch in the linear direction in the direction of arrow L, but when pressure is reduced, it is also possible to easily return soft actuator 110 to its initial state by the elastic displacement of regulating member 170.

[0044] <Description of Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS. Fig. 3 is an overall schematic diagram of a soft actuator system according to a second embodiment of the present invention, and Fig. 4 is a photograph showing an example of operation of the soft actuator system according to the second embodiment of the present invention.

[0045] 3 shows an accordion-shaped soft actuator system 200 according to a second embodiment of the present invention. As disclosed in Patent Document 7, the accordion-shaped soft actuator is a flexible actuator that includes a long movable part that performs a bending motion when liquid moves to a main liquid chamber, a reservoir chamber where liquid moves between the reservoir chamber and the main liquid chamber, a pump part that moves fluid between the reservoir chamber and the main liquid chamber, and a pump drive part that controls the drive of the pump part.

[0046] The soft actuator 210 shown in FIG. 3(B) has multiple connected fluid chambers 212 formed in an outer shell 214 that serves as a container. When a gas such as air or a fluid such as liquid is injected into the fluid chambers, the pressure in the fluid chambers 212 increases, and as the pressure increases, the soft actuator 210 extends from a curved state into a straight line.

[0047] As shown in Fig. 3(C) seen from the arrow X in Fig. 3(A), the connection adjustment members 220 are assembled by fitting the hinge tubes 224, 226 of adjacent connection adjustment members 220 into each other as in the first embodiment, and the pin 250 is inserted into the hole 222. Then, as shown in Fig. 3(A), the connection adjustment members 220 are attached to the soft actuator 210 via the attachment plate 228.

[0048] As shown in FIG. 3D, the restricting member 260 is a long thin plate, and has a plurality of holes 262 formed along the connecting direction of the connection adjusting member 220, through which the pins 250 are inserted.

[0049] This embodiment can be applied to a soft actuator having an accordion-like structure having multiple pressure chambers that are interconnected by appropriately positioning the regulating member 260 depending on the size and operating form of the parts required to control the soft actuator system.

[0050] Next, several examples of this accordion-like structure soft actuator system 200 will be shown. Figures 4(A), (B), and (C) all show the initial shape of the soft actuator system 200, and depending on the shape of the restricting member 260, it is possible to realize a curved state (A), a nearly straight state (B), or a warped state (C).

[0051] In Figs. 4(D) and (E), the actuator can be put into a twisted or bent state initially or when the actuator is energized.

[0052] The modified aspects of the present invention are not limited to the above description, and the following modifications are also possible, for example. (1) By changing the axial distance between the holes of the restricting member or the connection adjustment member, any initial shape can be obtained. For example, by increasing the axial distance, a warped shape is obtained, and by decreasing the axial distance, a curved shape is obtained. (2) By changing the size of the hole and the pin and providing a gap between them, the range of motion in the rotational direction can be adjusted and a twisting motion can be generated. (3) By changing the material of the restricting member or the connecting adjustment member to a material having elasticity such as rubber, the extending action becomes possible. (4) By adjusting the surface roughness of the pin, resistance can be added to the opening and closing action of the hinge. (5) By adding a spring material or a spring to the restricting member or the connecting and adjusting member, it is possible to easily maintain or restore the initial shape. (6) In the first embodiment of the present invention, a connection adjustment member having a form similar to a hinge is applied, however, there are many types of hinges, and it goes without saying that an appropriate type can be selected from commonly available types such as flat hinges, long hinges, retractable hinges, spring hinges, slide hinges, hidden hinges, torque hinges (free stop hinges), damper hinges (soft down hinges), click hinges, etc., depending on the requirements of the soft actuator system.

[0053] As described above, the present invention can provide a soft actuator system that converts the localized expansion and contraction motion of a fluid pressure soft actuator, including a pneumatic type, into non-linear motion. Furthermore, the present invention can provide a structure that allows the initial shape, operating direction, and bending point of the soft actuator to be adjusted without incorporating a mechanism or the like from the beginning. The aspects of the present disclosure are not limited to the above-described embodiments, and modifications are possible without departing from the spirit of the present disclosure. [Explanation of symbols]

[0054] 100,200···Soft actuator system 110,210 Soft actuator 112,212...fluid chamber 114...container 120,220... Connection adjustment parts 122,162,164,172,174,222,262...hole 124, 126, 224, 226... Connection adjustment parts 128,228···Installed version 160, 170, 260 Regulating member

Claims

1. a soft actuator having a fluid chamber capable of storing a working fluid therein and expanding and contracting due to the pressure of the working fluid; a connection adjustment member attached to the soft actuator and made of a material having a higher rigidity than the soft actuator; A soft actuator system comprising: a regulating member that links the connection adjustment members of the soft actuator having a plurality of the connection adjustment members and regulates the relative movement of the linked connection adjustment members.

2. 2. The soft actuator system according to claim 1, wherein the fluid chambers of adjacent soft actuators are in communication with each other.

3. The restricting member is formed with a plurality of holes aligned in a connecting direction. The connection adjustment member is formed with a pin that is inserted into the hole, 2. The soft actuator system of claim 1, wherein the pin rotates within the hole to regulate a rotational direction of the connection adjustment member.

4. 4. The soft actuator system according to claim 3, wherein a predetermined gap is formed between the pin inserted into the hole and an inner edge of the hole.

5. 2. The soft actuator system according to claim 1, wherein the regulating member is made of an elastic material having a higher rigidity than the soft actuator.

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