WO2023171113A1

WO2023171113A1 - Robot hand

Info

Publication number: WO2023171113A1
Application number: PCT/JP2023/000330
Authority: WO
Inventors: 勝也坂本; 春樹美濃島
Original assignee: 株式会社ブリヂストン
Priority date: 2022-03-08
Filing date: 2023-01-10
Publication date: 2023-09-14
Also published as: JP2023131052A

Abstract

A robot hand according to the present invention comprises: a fluid pressure actuator which is variable in a direction orthogonal to the axial direction; and a mounting base to which the fluid pressure actuator is mounted. In a state where the pressure of fluid is not applied, the fluid pressure actuator is fixed by the mounting base in such a manner as to be inclined outward in the direction of curvature of the fluid pressure actuator.

Description

robot hand

The present invention relates to a robot hand, particularly a robot hand equipped with a fluid pressure actuator.

It has been proposed to use a fluid pressure actuator (also called a "McKibben-type fluid pressure actuator") in the field of robots that can realize a desired motion by expanding and contracting a tube covered with a sleeve (for example, patents (See Reference 1). In Patent Document 1, a fluid pressure actuator is used not only as a lift part (robot arm) for lifting an object, but also as a grip part (finger robot hand) for realizing the behavior of a human finger.

Japanese Patent Application Publication No. 2021-088999

However, the above-mentioned robot hand has a problem in that it becomes difficult to grasp the object because it draws a trajectory in which the tip part rises when bending. There was also the problem that it was difficult to grasp large objects.

Therefore, an object of the present invention is to provide a robot hand with improved ability to grasp objects.

The gist of the present invention is as follows.
a fluid pressure actuator variable in a direction perpendicular to the axial direction;
A robot hand comprising: a mounting base to which the fluid pressure actuator is mounted;
The robot hand is characterized in that, in a state in which the fluid pressure is not applied, the fluid pressure actuator is fixed at the mounting base so as to be tilted outward in a curved direction of the fluid pressure actuator.

According to the present invention, it is possible to provide a robot hand with improved ability to grasp objects.

It is a side view of a fluid pressure actuator. FIG. 2 is a partially exploded perspective view of the fluid pressure actuator. FIG. 2 is a partial cross-sectional view along the axial direction DAX of a fluid pressure actuator including a sealing mechanism. FIG. 3 is a cross-sectional view of the actuator main body along the radial direction DR. It is an explanatory view of behavior of a fluid pressure actuator. FIG. 2 is a diagram showing an example of the configuration of a robot hand using a fluid pressure actuator. FIG. 2 is a diagram schematically showing the operation of a conventional robot hand. FIG. 3 is a diagram schematically showing the operation of the robot hand of this embodiment. FIG. 3 is a diagram schematically showing the trajectory of the tip of a fluid pressure actuator in a conventional robot hand. FIG. 3 is a diagram schematically showing the trajectory of the tip of the fluid pressure actuator in the robot hand of the present embodiment.

Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings.

<Fluid pressure actuator>
<<Overall schematic configuration of fluid pressure actuator>>
FIG. 1 is a side view of a fluid pressure actuator 10 according to this embodiment. As shown in FIG. 1, the fluid pressure actuator 10 includes an actuator main body 100, a sealing mechanism 200, and a sealing mechanism 300. Furthermore, connecting portions 20 are provided at both ends of the fluid pressure actuator 10, respectively.

The actuator main body 100 is composed of a tube 110 and a sleeve 120. Fluid flows into the actuator main body 100 through the connection port 211a.

As a basic characteristic, the actuator main body 100 contracts in the axial direction DAX and expands in the radial direction DR due to the inflow of fluid into the tube 110. Further, the actuator main body 100 expands in the axial direction DAX and contracts in the radial direction DR due to fluid flowing out from the tube 110. Due to such a shape change of the actuator main body 100, the fluid pressure actuator 10 exhibits its function as an actuator.

Such a fluid pressure actuator 10 is a so-called McKibben type, and can be used not only for artificial muscles but also for robot limbs (upper limbs, lower limbs, etc.) that require higher capacity (contractile force). It can be suitably used. The connecting portion 20 is connected to members constituting the limb.

In this embodiment, a McKibben-type fluid pressure actuator having such basic characteristics is used, and a restraining member 150 (FIG. 1 (not shown, see FIGS. 2, 3, etc.), it is possible to curve (curl) in the orthogonal direction perpendicular to the axial direction DAX, that is, in the radial direction DR.

The fluid used to drive the fluid pressure actuator 10 may be either a gas such as air or a liquid such as water or mineral oil, but the fluid pressure actuator 10 is particularly suitable for hydraulic drive where high pressure is applied to the actuator body 100. It has high durability that can withstand even

The sealing mechanism 200 and the sealing mechanism 300 seal both ends of the actuator main body 100 in the axial direction DAX. Specifically, the sealing mechanism 200 includes a sealing member 210 and a caulking member 230. The sealing member 210 seals the end of the actuator main body 100 in the axial direction DAX. Further, the caulking member 230 caulks the actuator main body portion 100 together with the sealing member 210. An indentation 231 is formed on the outer peripheral surface of the caulking member 230, which is a trace of the caulking member 230 being caulked with a jig.

The difference between the sealing mechanism 200 and the sealing mechanism 300 is whether or not a connection port 211a is provided.

The connection port 211a is attached with a hose (pipe line) connected to a driving pressure source of the fluid pressure actuator 10, specifically, a compressor for gas or liquid. (not shown) and flows into the inside of the actuator main body 100, specifically, into the inside of the tube 110.

FIG. 2 is a partially exploded perspective view of the fluid pressure actuator 10. As shown in FIG. 2, the fluid pressure actuator 10 includes an actuator main body 100 and a sealing mechanism 200.

The actuator main body 100 is composed of the tube 110 and the sleeve 120, as described above.

The tube 110 is a cylindrical body that expands and contracts depending on the pressure of the fluid. The tube 110 is made of an elastic material such as butyl rubber because it repeatedly contracts and expands with fluid. In addition, when the fluid pressure actuator 10 is hydraulically driven, it should be made of NBR (nitrile rubber), which has high oil resistance, or at least one selected from the group consisting of hydrogenated NBR, chloroprene rubber, and epichlorohydrin rubber. is preferred.

The sleeve 120 has a cylindrical shape and covers the outer peripheral surface of the tube 110. The sleeve 120 is a stretchable structure in which fiber cords oriented in a predetermined direction are woven together, and the oriented cords intersect to form a repeated diamond shape. By having such a shape, the sleeve 120 deforms in a pantograph and follows the contraction and expansion of the tube 110 while regulating it.

As the cord constituting the sleeve 120, it is preferable to use a fiber cord of aromatic polyamide (aramid fiber) or polyethylene terephthalate (PET). However, the cord is not limited to these types of fiber cords, and for example, cords of high-strength fibers such as PBO fibers (polyparaphenylenebenzobisoxazole) may be used.

Furthermore, in this embodiment, a restraining member 150 is provided between the tube 110 and the sleeve 120.

The restraint member 150 is not compressed in the axial direction DAX, but can be deformed only along the radial direction DR (which may also be referred to as the deflection direction). That is, the restraint member 150 resists compression along the axial direction DAX, and is deformable in the orthogonal direction (radial direction DR) perpendicular to the axial direction DAX.

In other words, the restraining member 150 has a characteristic that it is difficult to deform along the axial direction DAX and is flexible along the radial direction DR. Note that "deformable" may also mean "curvable" or "curlable".

The restraint member 150 also has a function of restraining (regulating) the expansion of the tube 110 (and sleeve 120) outward in the radial direction DR at a position on the outer circumference of the tube 110 where the restraint member 150 is provided. There is.

In the present embodiment, the restraint member 150 is provided inside the sleeve 120, specifically, in the space inside the sleeve 120 in the radial direction, from one end side to the other end side in the axial direction DAX. Further, in this embodiment, the restraint member 150 is formed using a leaf spring.

The dimensions of the leaf spring are not particularly limited, and may be selected depending on the size of the fluid pressure actuator 10 and the required force to be generated. Furthermore, the material of the leaf spring is not particularly limited, but typically any material that is easy to bend and strong against compression, such as metal such as stainless steel, may be used. For example, the restraint member 150 may be formed of a thin plate of carbon fiber reinforced plastic (CFRP). Since CFRP is less susceptible to plastic deformation than metal, the fluid pressure actuator 10 easily returns to its original straight state after being bent.

The sealing mechanism 200 seals the end of the actuator main body 100 in the axial direction DAX. The sealing mechanism 200 includes a sealing member 210, a locking ring 220, and a caulking member 230.

The sealing member 210 is inserted into the tubular actuator main body 100. Specifically, the sealing member 210 has a head portion 211 and a body portion 212, and the body portion 212 is inserted into the tube 110.

As the sealing member 210, a metal such as stainless steel can be suitably used, but the sealing member 210 is not limited to such a metal, and a hard plastic material or the like may also be used.

The locking ring 220 locks the sleeve 120 to the sealing member 210. Specifically, the sleeve 120 is folded back outward in the radial direction DR via the locking ring 220 (not shown in FIG. 2, see FIG. 3).

The locking ring 220 has a notch 221 that is partially cut out so that it can be engaged with the sealing member 210. As the locking ring 220, the same materials as the sealing member 210, such as metals and hard plastic materials, natural fibers (natural fiber threads), rubber (for example, O-rings), and other materials can be used.

The caulking member 230 caulks the actuator main body 100 together with the sealing member 210. Specifically, the caulking member 230 is provided on the outer peripheral surface of the portion of the actuator body 100 into which the sealing member 210 is inserted, and caulks the actuator body 100 to the sealing member 210 .

As the caulking member 230, metals such as aluminum alloy, brass, and iron can be used. When the caulking member 230 is caulked by the caulking jig, an indentation 231 as shown in FIG. 1 is formed on the caulking member 230.

<<Configuration of sealing mechanism 200>>
FIG. 3 is a partial cross-sectional view of the fluid pressure actuator 10 including the sealing mechanism 200 along the axial direction DAX.

As shown in FIG. 3, the tube 110 is inserted into the body portion 212. Further, the sleeve 120 is folded back to the outside in the radial direction DR via the locking ring 220.

A restraint member 150 is provided inside the sleeve 120 in the radial direction DR. Specifically, restraining member 150 is provided between tube 110 and sleeve 120.

Further, the restraining member 150 is provided in a part of the actuator main body 100 in the circumferential direction. That is, the restraint member 150 is provided only in a portion of the tube 110 (and sleeve 120) in the circumferential direction.

The restraint member 150 is provided from one end side to the other end side in the axial direction DAX of the actuator main body 100 (that is, the tube 110 and the sleeve 120). Specifically, the restraining member 150 may be provided from the sealing mechanism 200 to the sealing mechanism 300.

However, the restraining member 150 does not necessarily have to be provided completely from the sealing mechanism 200 to the sealing mechanism 300, and the restraining member 150 does not necessarily have to be provided completely over the sealing mechanism 200 and the sealing mechanism 300 (especially when the free end is bent). The restraining member 150 does not need to extend to the sealing mechanism 300 side (where there is a high possibility of this).

The caulking member 230 is larger than the outer diameter of the body portion 212 of the sealing member 210, and is inserted into the body portion 212 and caulked with a jig. The caulking member 230 caulks the actuator main body 100 together with the sealing member 210 .

Specifically, the caulking member 230 caulks the tube 110 inserted into the body portion 212 and the sleeve 120 located outside the tube 110 in the radial direction DR. That is, the caulking member 230 caulks the tube 110 and the sleeve 120 together with the sealing member 210.

<<Configuration of actuator main body 100>>
FIG. 4 is a cross-sectional view of the actuator main body 100 along the radial direction DR. As shown in FIG. 4, the restraining member 150 is provided between the tube 110 and the sleeve 120. The restraint member 150 may be in close contact with the tube 110 and the sleeve 120, or some gap may be formed between the restraint member 150 and the tube 110 and/or the sleeve 120, and on the sides of the restraint member 150. I don't mind.

The restraining member 150 is provided in a part of the tube 110 in the circumferential direction. The width of the restraint member 150 is not particularly limited, but if it is based on the outer diameter of the tube 110, it may be approximately half the outer diameter. As an example, the outer diameter of the tube 110 may be 11 mm, the length of the contracting actuator main body 100 portion may be 185 mm, and the width of the restraining member 150 (plate spring) may be 6 mm and the thickness may be approximately 0.5 mm.

In the present embodiment, the restraint member 150 has a flat plate shape, but it may be slightly curved along the cross-sectional shapes of the tube 110 and the sleeve 120 as long as it does not affect the way it bends.

<<Behavior of fluid pressure actuator 10>>
FIG. 5 is an explanatory diagram of the behavior of the fluid pressure actuator 10. In the fluid pressure actuator 10 shown in FIG. 5, the sealing mechanism 200 side is fixed, and the sealing mechanism 300 side is freely movable. That is, the sealing mechanism 200 side is a fixed end, and the sealing mechanism 300 side is a free end.

As described above, when fluid flows into the inside of the fluid pressure actuator 10, it tries to contract in the axial direction DAX, but since the restraining member 150 is provided, the contraction along the axial direction DAX is restrained (regulated). Ru.

In other words, the restraining member 150 formed of a hard member such as a leaf spring plays a role like a backbone, and the position opposite to the position on the outer periphery of the tube 110 and sleeve 120 where the restraining member 150 is provided (FIG. By expanding outward in the radial direction DR, the dimension of the fluid pressure actuator 10 in the axial direction DAX is shortened, and the fluid pressure actuator 10 (specifically, the actuator main body 100) is expanded along the direction D1. bends. Note that the direction D1 may also be referred to as a flexible direction.

The restraint member 150 is provided between the rubber tube 110 and the sleeve 120, and is a member that resists compression in the axial direction DAX and can be deformed along the orthogonal direction (radial direction DR). , are arranged in a part of the actuator main body 100 in the circumferential direction.

In other words, when the actuator main body 100 (McKibben) attempts to contract along the axial direction DAX due to fluid inflow (pressurization) into the actuator main body 100, the restraint member 150 has high compression rigidity, so the restraint member The part where 150 is placed cannot be contracted. On the other hand, other parts of the actuator main body 100 tend to contract, so a force in a bending direction along the orthogonal direction (radial direction DR) is generated, and the parts curve with the restraining member 150 as the back surface.

<<Example of configuration of robot hand using fluid pressure actuator 10>>
FIG. 6 shows an example of the configuration of a robot hand using the fluid pressure actuator 10. Specifically, FIG. 6 is a schematic side view of the system 30 including the robot hand 80.

As shown in FIG. 6, the robot hand 80 is configured using a plurality of fluid pressure actuators 10. The system 30 includes a plurality of fluid pressure actuators 10 , a fluid pressure actuator 15 , a pedestal 35 , a support 40 , an actuator connection 50 , and an actuator connection 60 .

The fluid pressure actuator 10 is a bendable McKibben-type actuator that includes the restraining member 150 as described above.

A support section 40 is provided upright on the upper surface of the pedestal section 35. The upper end portion of the support portion 40 is folded back downward, and the actuator connection portion 50 is connected to the tip portion of the support portion 40 .

A fluid pressure actuator 15 is suspended from the actuator connection portion 50. The fluid pressure actuator 15 is not provided with a restraining member like the fluid pressure actuator 10, is a general McKibben type actuator, and contracts and expands along the axial direction (arrow direction in the figure). That is, the fluid pressure actuator 15 simply changes its length in the axial direction, and cannot curve like the fluid pressure actuator 10.

An actuator connection portion 60 is connected to the lower end of the fluid pressure actuator 15. A plurality of fluid pressure actuators 10 are suspended from the actuator connection portion 60 .

The fluid pressure actuator 15 is larger than the fluid pressure actuator 10 and can generate a larger force. On the other hand, since the plurality of fluid pressure actuators 10 suspended from the actuator connection part 60 are curved, they can realize a behavior similar to a human finger.

The plurality of hydraulic actuators 10 can grip soft and fragile objects, such as chicken eggs, without damaging them. Further, the fluid pressure actuator 10 and the fluid pressure actuator 15 can also grip and lift an object that weighs more than a certain level, for example, a shot put shot (7.26 kg or more).

The fluid pressure actuator 10 has a large bending angle (bending 180 degrees or more), a large generated force (about 40 N), easy control of force (generated force is proportional to pressure), simple structure, and a coating on the surface. , it is also possible to directly touch the objects being handled.
Furthermore, the restraint member 150 provided in the fluid pressure actuator 10 resists compression of the actuator main body 100 (specifically, the tube 110) in the axial direction DAX, and resists compression in the radial direction DR perpendicular to the axial direction DAX. It can be transformed into.

Since the restraint member 150 is provided inside the tube 110, the size of the fluid pressure actuator 10 does not increase. Furthermore, the restraint member 150 can efficiently generate force in the bending direction.

That is, according to the fluid pressure actuator 10, it is possible to exert a larger force in the bending direction while avoiding an increase in size.

In this embodiment, the restraint member 150 is provided in a part of the tube 110 in the circumferential direction. Therefore, on the circumference of the actuator main body 100, there are parts that contract and parts that cannot contract, and when pressure is applied to the fluid pressure actuator 10, it moves in one direction (the side opposite to the side where the restraining member 150 is provided). curve. Thereby, force in the bending direction can be efficiently generated, and a larger force in the bending direction can be exerted.

In this embodiment, the restraining member 150 is provided between the tube 110 and the sleeve 120. Therefore, expansion of the tube 110 along the axial direction DAX can be effectively restrained (regulated). Thereby, force in the bending direction can be efficiently generated, and a larger force in the bending direction can be exerted.

Here, the robot hand 80 of the present embodiment includes (a) (a) a plurality of fluid pressure actuators 10 that are variable in a direction perpendicular to the axial direction, and (b) an attachment base 71 to which the fluid pressure actuator 10 is attached. A mounting portion 70 is provided.

In the illustrated example, the attachment part 70 is a plate-like member, and is installed so as to be substantially horizontal with the pedestal part 35. The attachment base 71 is disposed on the lower surface of the attachment portion 70 and has a shape in which the inner side in the curved direction of the fluid pressure actuator is thicker than the outer side in the curved direction. The attachment base 71 may be separate from the attachment portion 70, or may be formed integrally with it.

Further, in the illustrated example, four fluid pressure actuators 10 are provided at equal intervals of about 90 degrees on a plane parallel to the horizontal direction, but the number of fluid pressure actuators 10 is not limited to four, and , the intervals are not limited to equal intervals.

In this embodiment, the fluid pressure actuator 10 is fixed at the mounting base 71 so as to be inclined outward in the curve direction of the fluid pressure actuator 10 when no fluid pressure is applied. In other words, in a state where fluid pressure is not applied, the distance between the plurality of fluid pressure actuators 10 on the tip end side is larger than the distance on the attachment base 71 side.
The effects of the robot hand 80 of this embodiment will be described below.

FIG. 7A is a diagram schematically showing the operation of a conventional robot hand. FIG. 7B is a diagram schematically showing the operation of the robot hand of this embodiment. As schematically shown in FIG. 7A, in the conventional robot hand, since the bending direction of the fluid pressure actuator 20 is determined, it is difficult to grasp an object O that is larger than the distance between the tips of the fluid pressure actuator 20. Met. Moreover, since the curved direction of the fluid pressure actuator 20 is determined, the shape of the fluid pressure actuator 20 tends to be bent in the curved direction, which also makes it difficult to grip a large object O. On the other hand, as schematically shown in FIG. 7B, in the robot hand of this embodiment, in a state where no fluid pressure is applied, the fluid pressure actuator 10 is moved in the bending direction of the fluid pressure actuator 10 at the mounting base 71. Since it is tilted outward and fixed, the distance between the tips of the fluid actuator 10 is large (see the above diagram) when no fluid pressure is applied, and it is possible to grip even a relatively large object O ( (center view). Furthermore, since the fluid pressure actuator 10 can control the magnitude of the curvature in the curving direction by pressurizing the fluid, increasing the pressure increases the curvature and grips even a relatively small object O. (Figure below). In this way, according to the robot hand 80 of this embodiment, it is possible to improve grip performance in that it is possible to grip objects O of various sizes.

FIG. 8A is a diagram schematically showing the trajectory of the tip of the fluid pressure actuator in a conventional robot hand. FIG. 8B is a diagram schematically showing the trajectory of the tip of the fluid pressure actuator in the robot hand of this embodiment. As schematically shown in FIG. 8A, when the fluid pressure actuator 10 curves, the conventional robot hand draws a trajectory in which the tip of the fluid pressure actuator 10 rises, so it grasps the lower side of the object O. This makes it difficult to hold the object O, and the object O must be gripped on the upper side, resulting in an unstable grip. The above-mentioned shape of the fluid pressure actuator 20 in the curved direction also became a factor that made the grip even more unstable. On the other hand, as schematically shown in FIG. 8B, in the robot hand of this embodiment, in a state where fluid pressure is not applied, the fluid pressure actuator is mounted at the mounting base. Since it is fixed and inclined outward in the curve direction of the fluid pressure actuator, vertical displacement of the tip of the fluid pressure actuator 10 can be reduced when the fluid pressure actuator 10 is curved. Thereby, it becomes possible to grasp the lower side of the object O, and it becomes possible to stably grasp the object O. Note that the gripping position is not limited to the lower side of the object O. If there is a position suitable for gripping the object O, it is sufficient to grip that position, and it is sufficient to grip the upper side of the object O. You can also do it. In this way, according to the robot hand 80 of the present embodiment, the gripping performance can be improved in that the object O can be stably gripped.

In the example shown in FIG. 6, the four fluid pressure actuators 10 have the same inclination angle at which the fluid pressure actuators 10 are fixed at the mounting base 71 so as to be inclined outward in the curved direction of the fluid pressure actuators 10. However, the plurality of fluid pressure actuators 10 may have different inclination angles as long as the fluid pressure actuators 10 are fixed at the mounting base 71 so as to be inclined outward in the curved direction of the fluid pressure actuators 10. . However, it is preferable that the inclination angles of the fluid pressure actuators 10 at opposing positions be the same.

10, 15: Fluid pressure actuator, 20: Connection section, 30: Gripping system,
35: Pedestal part, 40: Support part, 50, 60: Actuator connection part,
70: Attachment part, 71: Attachment base, 80: Robot hand,
100, 100A, 100B: actuator main body,
110: tube, 120: sleeve, 150, 150A, 150B: restraint member,
151: piano wire, 160: spacing member, 200, 200A: sealing mechanism,
210: Sealing member, 211: Head, 211a: Connection port, 212: Body part,
220: Locking ring, 221: Notch, 230: Caulking member,
231: Indentation, 300: Sealing mechanism

Claims

a fluid pressure actuator variable in a direction perpendicular to the axial direction;
A robot hand comprising: a mounting base to which the fluid pressure actuator is mounted;
The robot hand is characterized in that, in a state in which the fluid pressure is not applied, the fluid pressure actuator is fixed at the mounting base so as to be tilted outward in a curved direction of the fluid pressure actuator.
The fluid pressure actuator is
a cylindrical tube that expands and contracts depending on fluid pressure;
a sleeve that is a stretchable structure woven with fiber cords oriented in a predetermined direction and that covers the outer peripheral surface of the tube;
The robot hand according to claim 1, further comprising a sealing member that seals an end of the tube in the axial direction.