JP7553000B2 - Gripping device and gripping method using the same - Google Patents

Description

The present invention relates to a gripping device that can stably grip (clamp) objects of various masses, sizes, and shapes without being affected by gravity, and a gripping method using the same.

Remote operation is essential in places that are out of reach, narrow spaces, underwater, in outer space, and in high radiation environments.
In such remote work, it was necessary to prepare a dedicated gripping device that matches the shape of the work tool, and multiple dedicated gripping devices that match the size and shape of the target object. This not only increased the cost of preparing the dedicated gripping devices, but also led to increased preparation time and replacement time during work.
In order to eliminate the need to prepare a gripping device suited to a work object, a gripping device has been proposed as described in Patent Literature 1. This gripping device grips an object using a bag containing powder or granular material, and stably grips the object by deforming the bag to match the shape of the object.

JP 2013-220492 A

However, the gripping device described in Patent Document 1 grips the object using only the frictional force between the bag body (flexible membrane) and the object, so if the object has a large mass or if the object is larger than the bag body and the contact area with the bag body cannot be increased, there is a risk that the object will not be gripped stably and will fall.
Furthermore, in this gripping device, since the powder accumulates on the lower side (tip side) of the bag, an object placed below the bag can be gripped. However, when gripping an object placed above the bag, for example, the powder moves to the lower side (base side) inside the bag due to the effect of gravity, so there is a risk that the object cannot be gripped.

The present invention was made in consideration of these circumstances, and aims to provide a gripping device and a gripping method using the same that can stably grip objects of various masses, sizes, and shapes without being affected by gravity.

A gripping device according to the present invention that meets the above-mentioned objective is a gripping device that is provided on a base portion and grips an object with a plurality of fingers, each of which has a deformable bag-like body filled with a liquid fluid and a powder or granular material, the gripping device comprising:
a hardening/softening means for discharging the liquid fluid from the bag-like body and supplying the liquid fluid to the bag-like body to make the bag-like body in a hardened state or a softened state is provided;
The powder or granular material is composed of two or more types of granular materials having different specific gravities.

In the gripping device according to the present invention, it is preferable that the powder or granular material has at least the granular material having a larger specific gravity than the liquid fluid and the granular material having a smaller specific gravity than the liquid fluid.

In the gripping device according to the present invention, the hardening means preferably includes a pump that discharges the liquid fluid from the bag-like body and supplies the liquid fluid to the bag-like body through a fluid transport tubing attached to the bag-like body, and a filter that is provided in the area where the fluid transport tubing is attached to the bag-like body and allows only the liquid fluid to pass through.

In the gripping device of the present invention, it is preferable that each finger portion further includes a reinforcing member on which the bag-shaped bodies are provided, and that the reinforcing member is tiltably provided on the base portion so that the bag-shaped bodies are moved closer to or farther away from each other by a driving means.
Here, the reinforcing member is preferably an elastic body.
The reinforcing member may be provided on the outside or inside of the bag-shaped body.

A gripping method according to a first aspect of the present invention that meets the above-mentioned objective is a gripping method using a gripping device according to the present invention,
a preparation step of gripping an object with the plurality of finger portions and bringing each of the bag-shaped bodies in a softened state into contact with the object;
a hardening step of discharging the liquid fluid from each of the bag-shaped bodies by the hardening/softening means and hardening each of the bag-shaped bodies;
During the process of discharging the liquid fluid from each bag-like body in the hardening step, the reinforcing member made of the elastic material causes the bag-like bodies on each finger portion to approach each other as the volume of each bag-like body decreases, thereby completing the gripping of the object.

A gripping method according to a second aspect of the present invention that meets the above-mentioned objective is a gripping method using a gripping device according to the present invention, comprising:
a preparation step of gripping an object with the plurality of finger portions and bringing each of the bag-shaped bodies in a softened state into contact with the object;
a hardening step of discharging the liquid fluid from each of the bags by the hardening/softening means to harden each of the bags;
a contact step of supplying the liquid fluid to each of the bag-shaped bodies by the hardening/softening means, softening each of the bag-shaped bodies, and contacting the bag-shaped bodies with the object,
After completion of the contact step, the hardener/softener means is used to discharge the liquid fluid from each of the bag-like bodies, and the contact step is performed until the bag-like bodies in the non-contact state come into contact with the object, provided that when each of the bag-like bodies is hardened, one or more of the bag-like bodies are in a non-contact state with the object.

The gripping device and gripping method using the same of the present invention have a plurality of fingers, each of which has a deformable bag-like body filled with liquid fluid and powdered material inside, and are provided with a hardening/softening means for discharging and supplying the liquid fluid from and to the bag-like body to harden and soften the bag-like body, so that when an object is gripped with the gripping device, each bag-like body deforms to fit (follow) the shape of the object.
Here, the powder and granular material inside the bag-shaped body is composed of two or more types of granular material with different specific gravities, so that, for example, when an object placed below or above the bag-shaped body is to be grasped with a gripping device, it is possible to suppress or even prevent all of the powder and granular material from moving only to the bottom or top of the bag-shaped body due to the influence of gravity, and therefore the object can be gripped stably.
Therefore, objects of various masses, sizes, and shapes can be stably grasped without being affected by gravity.

1 is a partial perspective view of a gripping device according to an embodiment of the present invention; FIG. 2 is an explanatory diagram showing a partial side view of the gripping device. FIG. 4 is an explanatory diagram showing an internal structure of a bag-shaped body of the gripping device. FIG. 1A and 1B are explanatory views showing the gripping device in a state before gripping an object and in a state after gripping the object, respectively. FIG. 2 is a perspective view of an entire gripping system using the gripping device. 4 is a flowchart showing the operation of the gripping device. 10 is a flowchart showing the operation of a gripping device according to a modified example.

Next, with reference to the attached drawings, an embodiment of the present invention will be described for understanding the present invention.
As shown in Figures 1 to 5 (A) and (B), a gripping device 10 according to one embodiment of the present invention is used, for example, as an end effector of an industrial robot (an end effector (gripping mechanism) used to grip an object, i.e., a gripper), and is a device that can stably grip (clamp) objects 11 of various masses, sizes, and shapes without being affected by gravity. Note that the object 11 to be gripped is not particularly limited, and may be, for example, various types of equipment, parts, food, etc., and has various masses, sizes, and shapes (for example, rod-shaped, plate-shaped, or spherical). A detailed explanation will be given below.

As shown in Figures 1 to 3, the gripping device 10 has a base portion 12, a plurality of finger portions 13 arranged in front of the base portion 12, a driving means (opening/closing mechanism) 14 arranged behind the base portion 12, and a hardening means (hardening mechanism) 15.
The number of fingers 13 provided on the base portion 12 is three here, but is not particularly limited as long as it is the number that is capable of grasping (clamping) and holding the object 11. Depending on the mass, size, shape, etc. of the object, the number may be, for example, two, or four or more (the upper limit is, for example, about ten).

As shown in FIGS. 1, 2, 5A and 5B, the finger portion 13 includes a plate-like reinforcing member 16 and a bag-like body 17 attached to one side of the reinforcing member 16.
An attachment portion 18 is provided at the base of the plate-shaped reinforcing member 16, and this attachment portion 18 is attached to the base portion 12 via a rotation shaft 19, making the reinforcing member 16 tiltable with respect to the base portion 12. Specifically, each reinforcing member 16 is disposed on the base portion 12 with one side of the reinforcing member 16 of each finger portion 13 facing each other with a gap therebetween so that the multiple finger portions 13 can grasp and hold the object 11.

This reinforcing member 16 is in the shape of a rectangular plate (strip) with its tip bent toward another reinforcing member 16; however, as long as the shape allows multiple fingers to grasp an object, it is not particularly limited; for example, the reinforcing member may be bent in multiple stages from the base to the tip toward the other reinforcing member, or the reinforcing member may be curved in an arc toward the other reinforcing member.
Furthermore, depending on the object to be grasped, the tip of the reinforcing member can be made wider or narrower than the remaining parts, and the reinforcing member can be rod-shaped (single or multiple) or net-shaped.

The thickness and material of the reinforcing member 16 are not particularly limited as long as the multiple finger portions 13 have the strength to grasp and hold the object 11. Depending on the mass, size, shape, etc. of the object to be grasped, the reinforcing member 16 can be made of, for example, a plastic or metal plate material (thin plate material), and it is preferable that the reinforcing member 16 be an elastic body.
As the elastic body, for example, a leaf spring (thin leaf spring, laminated leaf spring, etc.) or reinforced plastic can be used, and when a leaf spring is used, the type of leaf spring (spring constant) can be changed depending on the object to be grasped.

The bag-like body 17 is a hollow, deformable (flexible) body made of an elastic material such as NBR (acrylonitrile butadiene rubber) or silicone, and has a thickness sufficient to avoid being damaged by the liquid fluid 20 or powder/granular material 21 filled therein, or the object 11 with which it comes into contact.
The bag-like body 17 is provided from the base to the tip on one side of the reinforcing member 16 (one side of the opposing side of each reinforcing member 16). As a result, the bag-like bodies 17 attached to the multiple finger portions 13 face each other, and when the target object 11 is gripped by the multiple finger portions 13, each bag-like body 17 comes into contact with the surface of the target object 11.

In this way, the bag-like body 17 is attached to one side of the reinforcing member 16 (the reinforcing member 16 is on the outside of the bag-like body 17), but the bag-like body can also be placed over the reinforcing member from its tip to its base (the reinforcing member is inside the bag-like body), and multiple bag-like bodies can also be attached with intervals between them from the tip to the base of the reinforcing member.
The outer surface of the bag-shaped body 17 is untreated (the material of the bag-shaped body 17 remains), but for example, the outer surface of the bag-shaped body can be textured or an anti-slip material or the like can be attached in order to increase the frictional force with the object.

As shown in FIGS. 3 and 4, the inside of the bag-shaped body 17 is filled with a liquid fluid 20 and powder or granular material 21.
The liquid fluid 20 may be, for example, water, oil, or other liquid.
The powder 21 is, for example, a granular material (particle size, for example, about 1 to 5 mm) having an uneven shape, and is composed of two types (two kinds) of granular material (granular material A) 22 and granular material (granular material B) 23 having different specific gravities. In this case, it is preferable that the specific gravity of one of the granular materials 22 is made larger than the specific gravity of the liquid fluid 20 (for example, larger than 1 when the liquid fluid is water), and the specific gravity of the other granular material 23 is made smaller than the specific gravity of the liquid fluid 20 (for example, smaller than 1 when the liquid fluid is water). Note that the specific gravity of either one of the granular materials 22, 23 may be made the same as the specific gravity of the liquid fluid 20. The powdered or granular material 21 (granular materials 22, 23) may be, for example, coffee beans, silicon beads (beads), buckwheat husks, plastic granules, ceramic granules, glass granules, metal granules, etc., but it is also possible to artificially produce materials with different specific gravities (materials with intended specific gravities) using one or more of plastic, ceramic, glass, and metal.

The reason why the powder 21 is composed of two types of granular material 22, 23 having different specific gravities is that, depending on the position of the object 11 to be grasped, the powder in the bag-like body may be biased toward only the lower or upper side of the bag-like body due to the influence of gravity (for example, when the powder is not evenly distributed throughout the bag-like body, a jamming transition phenomenon described below occurs), making it impossible to grasp the object.
For example, if an object is placed above a bag-shaped body and the bag-shaped body that is trying to grasp the object is placed in a vertical direction, if the powder and granular material are composed only of granular material with a specific gravity greater than that of the liquid fluid, the powder and granular material will gather on the lower side of the bag-shaped body due to the influence of gravity, causing a jamming transfer phenomenon, and the object cannot be grasped. Also, if an object is placed below a bag-shaped body and the bag-shaped body that is trying to grasp the object is placed in a vertical direction, if the powder and granular material are composed only of granular material with a specific gravity smaller than that of the liquid fluid, the powder and granular material will gather on the upper side of the bag-shaped body due to the influence of gravity, causing a jamming transfer phenomenon, and the object cannot be grasped (see Figure 5 (A)).

In addition, when the powder 21 is composed of two types of granular materials 22, 23 having different specific gravities, the mixing ratio of the granular materials 22, 23 is preferably, for example, 40 to 60 volume % of one of the granular materials 22 (the mixing ratio of the other granular material 23 is, for example, 60 to 40 volume %), with the volume of the powder 21 (the entire granular materials 22, 23) being 100 volume %.
The powdered material may also be composed of three types of granular materials with different specific gravities. In this case, the powdered material may be composed of, for example, granular material a with a larger specific gravity than the liquid fluid, granular material b with a smaller specific gravity than the liquid fluid, and granular material c with the same specific gravity as the liquid fluid. Furthermore, when the powdered material is composed of four or more types of granular materials with different specific gravities (the upper limit is, for example, about 10 types), it is preferable to further add granular materials with specific gravities between the above-mentioned granular materials a and c, or between the above-mentioned granular materials b and c. It is also possible that all of the two or more types of granular materials with different specific gravities are larger or smaller than the liquid fluid.

The amount (volume) of powder or granular material 21 filled inside this bag-like body 17 is not particularly limited as long as the bag-like body 17 can deform to follow the surface shape of the object 11 when it comes into contact with the object 11, but it is preferable that the amount be, for example, 60 to 80%, with the internal volume of the bag-like body 17 in an expanded state being 100%.
Here, if the volume of the powder or granules is less than 60% of the internal volume of the bag-shaped body, the amount of powder or granules filled will be too small to accommodate the surface shape of the target object, while if the volume of the powder or granules exceeds 80% of the internal volume of the bag-shaped body, the amount of powder or granules filled will be too much, and the powder or granules will not move even when they come into contact with the target object, making it difficult for the bag-shaped body to deform.

As shown in Figs. 2 and 3, the driving means 14 is provided for each finger portion 13 (that is, one driving means 14 is provided for each finger portion 13).
The driving means 14 has a connecting rod 24, one end of which is attached to the mounting portion 18 on which the finger portions 13 are provided, and an actuator (cylinder (hydraulic or pneumatic, etc.)) 25, the tip of which is attached to the other end of the connecting rod 24. A pump 27 is connected to the actuator 25 via a tube 26, and the actuator 25 reciprocates when the pump 27 is operated. As a result, as shown in Figures 5(A) and (B) , a force acts on the reinforcing member 16 of the finger portions 13, and the multiple finger portions 13 tilt around the pivot shaft 19 relative to the base portion 12 in response to the movement of the actuator 25, and the opposing finger portions 13 open and close (the bag-like bodies 17 move closer to or farther away from each other).

As shown in Figs. 3 and 4, the hardness/softness means 15 is provided for each finger portion 13 (that is, one hardness/softness means 15 is provided for each finger portion 13).
The hardness/softness means 15 has an electric pump (an example of a pump) 28, a receiving tank 29, a tube (an example of a fluid conveying tubing) 30 connecting the electric pump 28, the receiving tank 29, and the bag-shaped body 17, and a filter 31 provided between the bag-shaped body 17 and the tube 30. The electric pump 28 discharges the liquid fluid 20 from the bag-shaped body 17 and supplies it to the bag-shaped body 17 via the tube 30, and the filter 31 allows only the liquid fluid 20 to pass between the bag-shaped body 17 and the tube 30 (it does not allow the powdered or granular material 21 to pass).

Here, when the electric pump 28 is operated to discharge the liquid fluid 20 from the bag-like body 17 of the finger portion 13, a jamming transition phenomenon occurs and the bag-like body 17 hardens (solidifies), and when the liquid fluid 20 is supplied (injected) into the bag-like body 17 of the finger portion 13, the bag-like body 17 softens. The discharge of the liquid fluid 20 from the bag-like body 17 and the supply of the liquid fluid 20 to the bag-like body 17 are performed instantaneously (for example, within about 3 seconds or less).
The filter 31 only needs to be provided in a position where the powder 21 in the bag-shaped body 17 does not enter the tube 30 (the attachment area of the tube 30 to the bag-shaped body 17).Here, the filter 31 is provided so as to protrude from the attachment portion of the tube 30 to the bag-shaped body 17, but it can also be provided at the attachment portion of the tube inside the bag-shaped body.

The driving means 14 and hardness/softness means 15 can be operated by moving the pump 27 and the electric pump 28, respectively, using a wired or wireless control means (not shown). The operation of the driving means 14 and hardness/softness means 15 can be performed, for example, by an operator or the like operating the control means while checking the operation of the finger portion 13 of the gripping device 10, but it can also be performed automatically based on a program inputted in advance into the control means, for example.

The gripping device 10 described above can be provided with the rear side of the base unit 12 at the tip of a robot arm 33 of a gripping system 32 shown in Fig. 6, and can be moved to any position within the operating range of the robot arm 33 by a controller (control means) 34. At this time, if the object 11 to be gripped is within the operating range of the robot arm 33, it can be gripped by the gripping device 10.
In this way, when the gripping device 10 is provided in the gripping system 32, the tube 26 of the drive means 14 and the tube 30 connected to the bag-shaped body 17 of the hard/soft means 15 are housed and arranged within the robot arm 33 and are respectively connected to a pump 27 and an electric pump 28 arranged outside the robot arm 33, but the tubes 26, 30 may also be arranged outside the robot arm 33.
Also, the controller 34 of the gripping system 32 and the control means of the gripping device 10 described above can be integrated together.

Next, a gripping method according to an embodiment of the present invention will be described with reference to Fig. 6 and Fig. 7. Note that, here, a case where the reinforcing members 16 of the multiple finger portions 13 are formed of elastic bodies (leaf springs) will be described.
First, the robot arm 33 of the gripping system 32 shown in FIG. 6 is moved to bring the fingers 13 of the gripping device 10 provided on the robot arm 33 closer to the target object 11 (step 1 (ST1): see FIG. 5(A)).

(Preparation process)
The multiple driving means 14 (pumps 27) are each operated to grip the target object 11 with the multiple finger portions 13, and each bag-like body 17 in a softened state is brought into contact with the target object 11 (step 2 (ST2)).
(Curing process)
The plurality of hardening/softening means 15 (electric pumps 28) discharge the liquid fluid 20 from each bag-like body 17, respectively, to harden each bag-like body 17. In the process of discharging the liquid fluid 20 from each bag-like body 17, the reinforcing member 16 made of an elastic material causes the bag-like bodies 17 provided on each finger portion 13 to approach each other as the volume of each bag-like body 17 decreases (the finger portions 13 naturally close in response to the shape of the object 11) (step 3 (ST3)).
For this reason, in the preparation step described above, it is preferable to grip the object 11 more tightly with the multiple fingers 13 (enough to warp the reinforcing member 16) in consideration of the reduction in volume of the bag-shaped body 17 in the hardening step.
This completes the gripping operation of the target object 11 (step 4 (ST4): (see FIG. 5(B))).

When the gripping operation is completed by the above-mentioned operation, all of the bag-like bodies 17 are deformed to fit the arbitrary shape of the target object 11, and a contact friction force is generated between the target object 11 and the outer surface of the bag-like bodies 17. In addition, due to the contact friction between the powder and granular materials 21 having an uneven shape inside the bag-like bodies 17 (between the granular materials 22, 22, between the granular materials 22, 23, and between the granular materials 23, 23), the bag-like bodies 17 become hard, and the target object 11 is restrained by the reinforcing members 16.
This makes it possible to stably grasp the object 11. Note that even if the object is, for example, a long rod whose center of gravity is unstable, or even if the object is large compared to the mass of the grasping device, it can be grasped stably.

Further, a gripping method according to a modified example will be described with reference to Fig. 6 and Fig. 8. Note that, here, for example, a case will be described in which the reinforcing members 16 of the multiple finger portions 13 are made of something other than an elastic body (such as a simple plate material).
First, the robot arm 33 of the gripping system 32 shown in FIG. 6 is moved to bring the fingers 13 of the gripping device 10 provided on the robot arm 33 closer to the target object 11 (step 1 (ST1): see FIG. 5(A)).

(Preparation process)
The multiple driving means 14 (pumps 27) are each operated to grip the target object 11 with the multiple finger portions 13, and each bag-like body 17 in a softened state is brought into contact with the target object 11 (step 2 (ST2)).
(Curing process)
The liquid fluid 20 is discharged from each bag-like body 17 by the plurality of hardening/softening means 15 (electric pumps 28), and each bag-like body 17 is hardened. At this time, due to the reduction in volume of each bag-like body 17, some or all (one or more) of the bag-like bodies 17 are brought into a non-contact state with the target object 11 (step 3 (ST3)).

(Contacting step)
The multiple hardening/softening means 15 supply liquid fluid 20 to each bag-like body 17, and each bag-like body 17 is softened. Then, the multiple driving means 14 are moved, the multiple finger portions 13 grasp the object 11, and each bag-like body 17 in the softened state is brought into contact with the object 11 again (step 4 (ST4)).
After the above-mentioned contact process is completed, the liquid fluid 20 is discharged from each bag-like body 17 using multiple hardener/softener means 15, and when each bag-like body 17 is hardened, it is determined whether all of the bag-like bodies 17 maintain a state of contact with the object 11, or whether some or all of the bag-like bodies 17 are in a non-contact state with the object 11.

The above-mentioned judgment can be made, for example, by visually checking a situation in which the object 11 is about to fall from the gripping device 10 when an operator moves the robot arm 33 using the controller 34. However, the judgment can also be made, for example, by detecting current fluctuations in each of the multiple driving means 14, or by attaching a pressure sensor or the like to the contact surface side of each bag-shaped body 17 with the object 11 and detecting pressure fluctuations, etc. (Step 5 (ST5)).
If it is determined that all of the bag-shaped bodies 17 and the target object 11 are maintaining contact with each other, the gripping operation is completed (step 6 (ST6): (see FIG. 5(B))).

On the other hand, if it is determined that one or more of the bag-like bodies 17 are not in contact with the object 11, the process returns to step 4, and the multiple hardening/softening means 15 supply liquid fluid 20 to each bag-like body 17, softening each bag-like body 17, and then the multiple driving means 14 are moved, the multiple finger portions 13 grasp the object 11, and each bag-like body 17 in the softened state is brought into contact with the object 11 again.
The operation of returning to step 4 described above is repeated until it is determined that all of the bag-like bodies 17 and the object 11 are maintaining a state of contact (until the bag-like bodies 17 that were in a non-contact state come into contact with the object 11).

Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the configurations described in the above embodiments, and includes other embodiments and modifications that are conceivable within the scope of the matters described in the claims. For example, the scope of the present invention also includes cases in which the gripping device and the gripping method using the same are configured by combining part or all of the above-mentioned embodiments and modifications.
In the above embodiment, a case has been described in which one finger portion is provided with one driving means and one hardness/softness means, but it is also possible to move two or more finger portions with one driving means, and it is also possible to move two or more finger portions with one hardness/softness means.
In the above embodiment, a filter that allows only liquid fluid to pass through is provided in the connection area between the bag-shaped body and the tube. However, the filter can be omitted, for example, if the inner cross-sectional area of the tube is smaller than the size (minimum width) of the powder or granular material.
Furthermore, in the above embodiment, the finger portion is provided with a reinforcing member, but depending on the object to be grasped, the reinforcing member may not be used. In this case, it is not necessary to provide a driving means for tilting the reinforcing member.

The gripping device and gripping method using the same according to the present invention can stably grip objects of various masses, sizes, and shapes without being affected by gravity. This allows it to be effectively used, for example, as an end effector for industrial robots, facilitating remote-controlled work in places that are out of reach of humans, narrow spaces, underwater, in outer space, and in high radiation environments.

10: gripping device, 11: object, 12: base, 13: finger, 14: driving means, 15: hard/soft means, 16: reinforcing member, 17: bag-shaped body, 18: mounting part, 19: rotating shaft, 20: liquid fluid, 21: powder, 22: granular material (granular material A), 23: granular material (granular material B), 24: connecting rod, 25: actuator, 26: tube, 27: pump, 28: electric pump (pump), 29: receiving tank, 30: tube (tube material for transporting fluid), 31: filter, 32: gripping system, 33: robot arm, 34: controller

Claims (7)

A gripping device that grips an object using a plurality of fingers provided on a base and each of the fingers has a deformable bag-like body filled with a liquid fluid and a powder or granular material,
a hardening/softening means for discharging the liquid fluid from the bag-like body and supplying the liquid fluid to the bag-like body to make the bag-like body in a hardened state or a softened state is provided;
A gripping device characterized in that the powdered material is composed of two or more types of granular materials having different specific gravities, and the powdered material has at least one granular material having a larger specific gravity than the liquid fluid and one granular material having a smaller specific gravity than the liquid fluid. In the gripping device according to claim 1, the hardening means comprises a pump that discharges the liquid fluid from the bag-like body and supplies the liquid fluid to the bag-like body through a fluid conveying tube attached to the bag-like body, and a filter that is provided in the attachment area of the fluid conveying tube to the bag-like body and allows only the liquid fluid to pass through. A gripping device characterized in that the hardening means comprises a pump that discharges the liquid fluid from the bag-like body and supplies the liquid fluid to the bag-like body through a fluid conveying tube attached to the bag-like body, and a filter that is provided in the attachment area of the fluid conveying tube to the bag-like body and allows only the liquid fluid to pass through. The gripping device according to claim 1 or 2, characterized in that each finger portion further includes a reinforcing member on which the bag-shaped body is provided, and the reinforcing member is tiltably provided on the base portion so that the bag-shaped bodies are moved toward or away from each other by a driving means. The gripping device according to claim 3, characterized in that the reinforcing member is provided on the outside or inside of the bag-shaped body. The gripping device according to claim 3 or 4, characterized in that the reinforcing member is an elastic body. A gripping method using the gripping device according to claim 5,
a preparation step of gripping an object with the plurality of finger portions and bringing each of the bag-shaped bodies in a softened state into contact with the object;
a hardening step of discharging the liquid fluid from each of the bag-shaped bodies by the hardening/softening means and hardening each of the bag-shaped bodies;
a gripping method characterized in that, during the process of discharging the liquid fluid from each of the bag-like bodies in the hardening process, the reinforcing member made of the elastic material causes the bag-like bodies provided on each of the finger portions to approach each other as the volume of each of the bag-like bodies decreases, thereby completing gripping of the object. A gripping method using the gripping device according to any one of claims 1 to 5,
a preparation step of gripping an object with the plurality of finger portions and bringing each of the bag-shaped bodies in a softened state into contact with the object;
a hardening step of discharging the liquid fluid from each of the bags by the hardening/softening means to harden each of the bags;
a contact step of supplying the liquid fluid to each of the bag-shaped bodies by the hardening/softening means to soften each of the bag-shaped bodies , and then contacting each of the bag-shaped bodies with the object,
A gripping method characterized in that after the contact step is completed, the hardener/softener means discharges the liquid fluid from each of the bag-like bodies, and the contact step is performed until the bag-like bodies in a non-contact state from which the liquid fluid has been discharged come into contact with the object, provided that when each of the bag-like bodies is hardened, one or more of the bag-like bodies are in a non-contact state with the object.

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