JP7686541B2 - membrane bag complex - Google Patents

Description

Article 30, paragraph 2 of the Patent Act applies (1) Website address: https://www.sice-si.org/conf/si2020/index.html Date posted: December 15, 2020 (2) Website address: https://www.sice-si.org/conf/si2020/online_pass/proceedings.html Date posted: December 15, 2020 (3) Name of the meeting: Robotics and Mechatronics Symposium 2021 in Osaka Date held: June 6, 2021

This disclosure relates to a membrane bag complex.

The environment surrounding factories in Japan is extremely tough due to labor shortages caused by the declining population. As a result, the automation of manufacturing processes is progressing, but assembling the diversified parts that have become more common due to the recent trend of high-mix, low-volume production using a common tool is a challenging task. In an assembly tool, a device that grips or manipulates parts is, for example, an end effector. In order to grip a variety of workpieces with the same end effector, a method has been proposed in which a mechanism that can change the rigidity is installed in the end effector.

One example of a variable stiffness mechanism is a bag gripper device, which is a type of soft gripper mechanism. The bag gripper device has a configuration in which contents whose stiffness can be changed are sealed in the internal space of a bag body. The bag gripper device presses the bag body in a soft state against the workpiece, so that it conforms to the shape of the workpiece, and then switches the inside of the bag body to a hard state to maintain the shape of the bag body, thereby gripping the workpiece. As a method for achieving switching of the stiffness of the bag body, a method has been proposed in which a magnetorheological or electrorheological fluid is sealed in the bag body and a magnetic field or electric field is applied to increase the viscosity of the fluid in the bag body (see, for example, Patent Documents 1 and 2).

The bag gripper device described in Patent Document 1 is a bag gripper device that uses a magnetorheological fluid. This bag gripper device uses a mechanism that can change the distance between a permanent magnet and the bag body as a means for increasing or decreasing the magnetic field, and generates a strong magnetic field with a smaller mechanism than when an electromagnet is used as a means for increasing or decreasing the magnetic field.

The bag gripper device described in Patent Document 2 has a configuration in which a magnetorheological fluid or an electrorheological fluid is sealed inside the bag, and the viscosity of the fluid inside the bag can be controlled using an electromagnet or a high-voltage electrode. In this bag gripper device, a pressure sensor is provided inside the bag, and the internal pressure of the bag is adjusted by a fluid supply and discharge mechanism, thereby changing the mechanical compliance of the bag, thereby improving the gripping ability.

Patent No. 6385014 JP 2004-154909 A

However, the hardening of magnetic or dielectric fluids or powders only occurs within the range of the magnetic field or electric field. For this reason, in configurations such as those in Patent Documents 1 and 2, as the size of the gripper (bag) increases, there is a risk that the hardening of the fluid or powder at the tip of the gripper will be insufficient, or that the fluid or powder will not harden at all.

The present disclosure aims to provide a membrane bag composite that can grip a variety of workpieces.

The membrane bag composite of the present disclosure comprises a flexible bag having an opening, the bag being filled with a hardenable medium made of a fluid or powder, a base member arranged to close the opening of the bag, the base member having a communication hole connecting the inside and outside of the bag, and a hardening part inserted into the communication hole so as to be movable in the central axial direction of the communication hole, the hardening part holding the bag in any shape by hardening the hardenable medium.

The membrane bag composite of the present disclosure can grip a variety of workpieces.

FIG. 1 is a schematic side view of a bag gripper according to a first embodiment; FIG. 1 is a schematic side view showing a state in which a bag gripper grips a workpiece in the first embodiment; FIG. 1 is a schematic vertical cross-sectional view of a bag gripper according to a first embodiment; FIG. 1 is a schematic vertical cross-sectional view showing a state in which a bag gripper in a first embodiment grips a workpiece; FIG. 5 is a schematic cross-sectional view of the bag gripper according to the first embodiment taken along line A-A in FIG. FIG. 1 is a schematic side view of a gripping system according to a first embodiment; FIG. 11 is a schematic side view of another example of the gripping system according to the first embodiment; FIG. 1 is a schematic side view of a jig system according to a first embodiment; FIG. 1 is a schematic side view of a legged robot system according to a first embodiment; FIG. 13 is a schematic vertical cross-sectional view of a bag gripper according to a second embodiment; FIG. 13 is a schematic vertical cross-sectional view of a bag gripper according to a third embodiment; FIG. 12 is a schematic cross-sectional view of the bag gripper according to the third embodiment taken along line BB in FIG. FIG. 13 is a schematic vertical cross-sectional view of a bag gripper according to a fourth embodiment; FIG. 13 is a schematic vertical cross-sectional view of a bag gripper according to a fifth embodiment; FIG. 13 is a schematic vertical cross-sectional view of a bag gripper according to a sixth embodiment;

[Embodiment]
An embodiment of the present disclosure will be described.

First Embodiment
Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. In the first embodiment, a bag gripper will be described as an example of a membrane bag composite of the present disclosure. However, the membrane bag composite of the present disclosure is not limited to a bag gripper, and can be widely used in a gripping device, a jig, a robot arm, and the like.

Figure 1 is a schematic side view of a bag gripper 1 in the first embodiment. As shown in Figure 1, the bag gripper 1 includes a bag body 2 and a housing 3.

The bag body 2 is formed of a flexible material, such as silicone rubber, into a semi-elliptical sphere with one opening. The shape of the bag body 2 is not limited to a semi-elliptical sphere, and may be, for example, a semi-spherical or cylindrical shape. The bag body 2 can flexibly conform to the workpiece. The inside of the bag body 2 is filled with a magnetorheological fluid. The magnetorheological fluid is an example of a hardenable medium of the present disclosure.

The bag gripper 1 is connected to the control device 4 via a connection member 5. The connection member 5 is made of an electric wire.

The control device 4 applies a first electrical signal to the bag gripper 1 via the connection member 5 after the bag body 2 is pressed against the workpiece and closely wraps around the workpiece. Application of this first electrical signal increases the viscosity of the magnetorheological fluid, causing the bag body 2 to harden while wrapping around the workpiece, and as a result, the bag gripper 1 can grip the workpiece. In the first embodiment, the control device 4 is installed outside the bag gripper 1, but if the control device 4 is installed inside the bag gripper 1, the connection member 5 does not need to be installed.

Figure 2 is a schematic side view showing the bag gripper 1 in the first embodiment gripping a workpiece.

The bag gripper 1 grips the workpiece 6 when a first electrical signal is applied by the control device 4, and releases the grip of the workpiece 6 when a second electrical signal is applied. There is no particular limitation on the shape of the workpiece 6 to be gripped by the bag gripper 1. It is preferable that the workpiece 6 does not damage the bag body 2. An example of a workpiece 6 that may damage the bag body 2 is an object coated with a chemical that dissolves the bag body 2, or an object that may pierce or wear the bag body 2, creating a hole in the bag body 2 and causing the bag body 2 to lose its airtightness.

Figure 3 is a schematic vertical cross-sectional view of the bag gripper 1 in the first embodiment. The bag gripper 1 further includes a base member 7, a magnetorheological fluid 8, a cylindrical member 9, a seal member 10, a magnet 11, a magnet fixing member 12, a linear actuator 13, a cylindrical member side elastic element 14, a magnet side elastic element 15, and a guide mechanism 16.

A linear actuator 13 is fixed to the other end side (the upper end side in FIG. 3) of the housing 3. The linear actuator 13 comprises a main body 13A fixed to the housing 3 and a moving element 13B that moves relative to the main body 13A. The linear actuator 13 is configured such that when a first electrical signal is applied by the control device 4, the moving element 13B moves in a direction away from the main body 13A, and when a second electrical signal is applied, the moving element 13B moves in a direction approaching the main body 13A.

A base member 7 is fixed to one end of the housing 3 (the lower end in FIG. 3). A guide mechanism 16 is fixed to the other end side of the housing 3 from the base member 7.

The bag body 2 is fixed to the base member 7, for example, by adhesive. The opening of the bag body 2 is blocked by the base member 7 so that the bag body 2 is watertight. The inside of the bag body 2 is filled with a magnetorheological fluid 8. The base member 7 has the same number of communication holes as the number of cylindrical members 9 (12). Each communication hole of the base member 7 is formed so as to communicate the inside and outside of the bag body 2. Each communication hole of the base member 7 has a cylindrical member 9 inserted therein. The communication holes of the base member 7 and the cylindrical member 9 are sealed by a seal member 10 so that the communication holes are watertight. The elasticity of the seal member 10 allows the cylindrical member 9 to tilt slightly while maintaining watertightness. In this way, the base member 7 is configured so that the cylindrical member 9 can move within the communication hole while maintaining the watertightness of the bag body 2.

The cylindrical member 9 has a cylindrical structure with a closed end on the bag body 2 side (hereinafter, sometimes referred to as the "tip end"). The cylindrical member 9 is guided by a guide mechanism 16 so that it can move in a direction along the central axis of the communication hole of the base member 7. A protrusion is formed on the end of the cylindrical member 9 on the linear actuator 13 side (hereinafter, sometimes referred to as the "base end"). This protrusion prevents the cylindrical member 9 from falling out of the base member 7 toward the bag body 2 side. The cylindrical member 9 is fixed to the guide mechanism 16 via a cylindrical member side elastic element 14. The cylindrical member 9 is given an elastic force toward the bag body 2 side by the cylindrical member side elastic element 14. The guide mechanism 16 has a function of preventing the cylindrical member 9 from falling out toward the linear actuator 13 side.

The hardening portion of the first embodiment includes a cylindrical member 9 and a magnet 11. The magnet 11 is formed in a rod shape. The magnet 11 moves toward the bag body 2 together with the cylindrical member 9 through the hole of the guide mechanism 16 and the communication hole of the base member 7, thereby applying a magnetic force to the magnetorheological fluid 8 and hardening the magnetorheological fluid 8.

The end of the magnet 11 opposite the bag body 2 is fixed to the magnet fixing member 12, for example, by adhesive. The magnet fixing member 12 is fixed to the moving element 13B of the linear actuator 13 via the magnet side elastic element 15. The magnet 11 can move in a direction along the central axis of the hole of the guide mechanism 16. The tubular member side elastic element 14 and the guide mechanism 16 function as a guide for the linear movement of the magnet 11. The magnet fixing member 12 is made of a material such as hard resin. The magnet 11 has a diameter smaller than the inner diameter of the tubular member 9, and is configured to be insertable into the interior of the tubular member 9.

The cylindrical member side elastic element 14 is composed of a spring. It is desirable to set the initial load and spring constant of the cylindrical member side elastic element 14 so that the cylindrical member 9 does not move toward the linear actuator 13 under its own weight, regardless of the position of the bag gripper 1 relative to the direction of gravity.

The magnet side elastic element 15 is composed of a spring. It is desirable to set the spring constant of the magnet side elastic element 15 so that the magnet 11 does not move significantly under its own weight, regardless of the position of the bag gripper 1 relative to the direction of gravity. The larger the spring constant of the magnet side elastic element 15, the faster the return speed of the magnet 11. However, if the spring constant of the magnet side elastic element 15 is large, the reaction force from the workpiece 6 required to deform the bag body 2 becomes large, which is disadvantageous in gripping flexible or fragile workpieces.

In order to allow the bag body 2 to harden all the way to the tip, it is desirable that the tip of the magnet 11 reach the tip of the tubular member 9 when the linear actuator 13 is fully extended without gripping a workpiece (when the moving element 13B is furthest from the main body 13A). It is desirable to design the bag gripper 1 so that when the linear actuator 13 is fully retracted without gripping a workpiece (when the moving element 13B is closest to the main body 13A), the entire magnet 11 completely comes out of the tubular member 9, and the magnetic force of the magnet 11 acts as little as possible on the magnetorheological fluid 8.

The shape of the tubular member 9 is not limited to a cylindrical shape, and may be, for example, a hexagonal cylindrical shape. The smaller the interval between adjacent tubular members 9, the higher the viscosity of the magnetorheological fluid 8 can be. The shape of the tip of the tubular member 9 is not limited to a straight cylinder, and by making the shape cylindrical with an inner diameter that increases toward the base end, the magnet 11 can be inserted more easily, but the amount of tilt allowed for the tubular member 9 may be more limited.

The material of the cylindrical member 9 is preferably a substance with low coercivity and high magnetic permeability. An example of a material with low coercivity and high magnetic permeability is soft iron. However, if the magnetic force of the magnet 11 is large and the magnet 11 does not move even when the linear actuator 13 is extended due to friction caused by the magnet 11 attracting the cylindrical member 9, the material of the cylindrical member 9 is preferably a non-magnetic material. For example, the cylindrical member 9 is preferably made of a resin material. In this case, it is preferable that the thickness of the cylindrical member 9 is thin so that the magnetic lines can easily pass through.

The number of cylindrical members 9 is not limited to 12, and may be any number as long as the magnetic field lines are arranged to sufficiently penetrate the magnetorheological fluid 8.

Although the tubular member 9 is configured from a single cylindrical member, it may have a telescopic structure. The telescopic structure in this disclosure is a structure that has a maximum length in an unloaded state and has elasticity such that an elastic force acts in the direction of extension when an external force is applied to contract it. By making the tubular member 9 a telescopic structure, the length in the axial direction of the bag gripper 1 of the guide mechanism 16 (the direction in which the linear actuator 13 extends) can be shortened. As a result, the axial length of the bag gripper 1 can be shortened. However, in the case of a structure in which the diameter of the part of the tubular member 9 that contacts the sealing member 10 changes as the telescopic structure of the tubular member 9 expands and contracts, it is required that the watertightness or airtightness of the inside of the bag body 2 provided by the sealing member 10 is not lost regardless of the expansion and contraction of the telescopic structure.

The number of linear actuators 13 is not limited to one, and multiple actuators may be provided. For example, the same number of actuators may be provided as the number of magnets 11, and each linear actuator 13 may move each magnet 11 independently.

In the example of FIG. 3, an electric cylinder is shown as an example of the linear actuator 13, but a pneumatic cylinder may also be used. When a pneumatic cylinder is used, for example, the following configuration may be applied. That is, a pneumatic control device is used as the control device 4, and an air tube is used as the connection member 5. A piston rod is used as the magnet fixing member 12, and a cylinder tube is used as the guide mechanism 16, and a pneumatic cylinder structure is arranged in which a piston packing is provided on the piston rod to make the space between the piston rod and the cylinder tube airtight. Furthermore, a pneumatic linear actuator is arranged to linearly move the piston rod of the pneumatic cylinder structure. In this case, each pneumatic linear actuator may apply air pressure to the extension side or contraction side all at once, rather than being driven independently, and the magnet side elastic element 15 can be omitted because the pneumatic cylinder functions as an air spring.

3, the moving element 13B of the linear actuator 13 is directly fixed to one end of the magnet side elastic element 15, but the present invention is not limited to this, and the moving element 13B of the linear actuator 13 may be connected to one end of the magnet side elastic element 15 via a power transmission mechanism such as a wire mechanism, a link mechanism, or a fluid pressure tube. For example, the linear actuator 13 is disposed outside the housing 3, and the power of the linear actuator 13 is transmitted to the magnet side elastic element 15 by the power transmission mechanism, thereby reducing the axial size of the bag gripper 1. If the power transmission mechanism has elasticity and can achieve the same function as the magnet side elastic element 15, one end of the power transmission mechanism may be directly fixed to one end of the magnet fixing member 12 without providing the magnet side elastic element 15. The linear actuator 13 is not limited to a linear actuator, and may be, for example, a rotary actuator, as long as it is a mechanism that linearly moves the magnet side elastic element 15 via the power transmission mechanism.

Figure 4 is a schematic vertical cross-sectional view showing the bag gripper 1 gripping the workpiece 6 in the first embodiment. When the workpiece 6 is pushed into the bag body 2, the bag body 2 is deformed and the tubular member 9 is pushed up towards the linear actuator 13. The linear actuator 13 is then extended by applying a first electrical signal from the control device 4, and when the magnet 11 moves to the tip of the inside of the tubular member 9, magnetic field lines pass through the magnetorheological fluid 8. When the magnetic field lines pass through the magnetorheological fluid 8, the viscosity of the magnetorheological fluid 8 increases and the bag gripper 1 grips the workpiece 6.

The magnets 11 attract each other due to magnetic field lines. Because the sealing member 10 arranged between the base member 7 and the cylindrical member 9 has elasticity, a force acts on the cylindrical member 9 in the direction toward the central axis of the bag body 2 due to the force of the magnets 11 attracting each other. This force acting in the direction toward the central axis of the bag body 2 has the effect of preferentially hardening the magnetorheological fluid 8 in the vicinity of the workpiece 6 gripped near the central axis of the bag body 2, and also acts as a gripping force for the workpiece 6. In addition, because there is a guide mechanism 16 between the magnets 11 on the linear actuator 13 side of the base member 7, the magnets 11 are attracted to each other due to magnetic field lines, and the magnets 11 do not become stuck even if the linear actuator 13 is extended due to frictional force generated by the magnetic force.

The sealing member 10 is highly elastic and allows for a slight tilt relative to the tubular member 9, but even if the sealing member 10 is configured to not allow tilt relative to the tubular member 9, the bag gripper 1 still has gripping capabilities.

On the other hand, when the linear actuator 13 is retracted by applying a second electrical signal by the control device 4, the magnet 11 comes out of the tubular member 9 and the magnetic field lines no longer pass through the magnetorheological fluid 8. When the magnetic field lines no longer pass through the magnetorheological fluid 8, the viscosity of the magnetorheological fluid 8 decreases, and the grip of the workpiece 6 by the bag gripper 1 is released. As the grip of the workpiece 6 is released, the tubular member 9 is pushed back toward the bag body 2 by the tubular member side elastic element 14.

Figure 5 is a schematic cross-sectional view of the bag gripper 1 in the first embodiment taken along line A-A in Figure 4. In Figure 5, 11a is the north pole of the magnet 11, 11b is the south pole of the magnet 11, and 17 is a magnetic field line. The magnetic field line 17 penetrates the magnetorheological fluid 8, thereby increasing the viscosity of the magnetorheological fluid 8.

In the example of magnet 11 in FIG. 5, in the entire area in the central axis direction, the area on one side of a plane that includes the central axis and is parallel to the central axis is a north pole 11a, and the area on the other side is a south pole 11b. Multiple such magnets 11 are arranged so that the north poles 11a and the south poles 11b are alternately positioned on a concentric circle centered on the central axis of the bag body 2. Note that, for example, multiple magnets 11 with the north pole 11a on one end side in the central axis direction and the south pole 11b on the other end side may be arranged on a concentric circle centered on the central axis of the bag body 2, and so that the north poles 11a and the south poles 11b are alternately positioned on the concentric circle.

Next, the gripping system according to the first embodiment will be described. FIG. 6 is a schematic side view of the gripping system. In the gripping system, the bag gripper 1 is attached to the hand portion 19 of a robot arm 18. The robot arm 18 can move three-dimensionally within a predetermined movable range and can assume any posture.

In the example of FIG. 6, the robot arm 18 is fixed to the upper surface of the robot support stand 20, but it may be fixed directly to the floor surface. In the example of FIG. 6, the robot arm 18 is a vertical multi-joint robot, but is not limited to this and may be, for example, a horizontal multi-joint robot or a parallel link robot. In the example of FIG. 6, the workpiece 6 is placed directly on the floor surface, but is not limited to this and may be, for example, in a container.

The bag gripper 1 can stably grip the workpiece 6 even if the orientation of the workpiece 6 is not constant, as the bag body 2 follows the shape of the workpiece 6. When the workpieces 6 are close to each other, it is desirable to control the robot arm 18 so that the bag gripper 1 does not grip another workpiece 6 adjacent to the workpiece 6 to be gripped at the same time.

The connection member 5 is, for example, a shielded multi-core electric wire. It is desirable that the connection member 5 is flexible enough not to interfere with the movement of the robot arm 18.

The control device 4 is connected to the bag gripper 1 by a connection member 5, and after pressing the bag gripper 1 against the workpiece 6 with the robot arm 18, applies a first electrical signal to the bag gripper 1 to increase the viscosity of the magnetorheological fluid 8 in the bag body 2, thereby hardening the bag body 2. This hardening of the bag body 2 causes the bag gripper 1 to grip the workpiece 6. The control device 4 also applies a second electrical signal to the bag gripper 1 to reduce (return to original) the viscosity of the magnetorheological fluid 8 in the bag body 2, thereby softening the bag body 2. This softening of the bag body 2 causes the bag gripper 1 to release its grip on the workpiece 6.

In the example of FIG. 6, the control device 4 is installed on the floor, but it may be installed in another location as long as the above-mentioned functions of the bag gripper 1 are not impaired. For example, the control device 4 may be fixed to the robot arm 18.

Figure 7 is a schematic side view of another example of the gripping system in the first embodiment. In this example of the gripping system, the bag gripper 1 described above is disposed on each of the claws 22 of the two-finger gripper 21.

The two-finger gripper 21 clamps the workpiece 6 with the bag gripper 1 provided on each of the claws 22. The control device 4 then applies a first electrical signal to the bag gripper 1 to harden the bag body 2. As the bag body 2 hardens, the two bag grippers 1 grip the workpiece 6. The control device 4 also applies a second electrical signal to the bag gripper 1 to soften the bag body 2, and then the two-finger gripper 21 opens the claws 22. As the bag body 2 softens and the claws 22 open, the two bag grippers 1 release their grip on the workpiece 6. According to the example of FIG. 7, not only is the gripping force of the two-finger gripper 21 and the gripping force of the bag gripper 1 simply matched, but the bag body 2 is configured to follow the shape of the workpiece 6, so that the bag gripper 1 is not disposed on the claws 22 and the claws 22 directly grip the workpiece 6. This allows for more stable gripping of the workpiece 6 compared to when the bag gripper 1 is not disposed on the claws 22 and the claws 22 directly grip the workpiece 6.

In the example of Figure 7, when releasing the grip, the bag body 2 is softened and then the claws 22 are opened, but this is not limited thereto, and if the gripping force of the bag gripper 1 alone is not sufficient to grip the workpiece 6, the claws 22 may be opened first and then the bag body 2 may be softened. In the example of Figure 7, the bag gripper 1 is attached to a two-fingered gripper 21, but this is not limited thereto, and the bag gripper 1 may be attached to a multi-fingered hand with three or more fingers. In addition to positions corresponding to the fingertips of the gripper, the bag gripper 1 may also be positioned, for example, at a position corresponding to the palm, so that the shape of the entire gripper can be made to conform to the workpiece 6.

Next, the fixture system according to the first embodiment will be described. FIG. 8 is a schematic side view of the fixture system. In the fixture system, the bag gripper 1 is attached to a hand portion 19 of a robot arm 18, which can move up and down and rotate freely. In the example of FIG. 8, the workpiece 6 is a screw part with a slot in the head, and is attached to a female threaded hole in a work-in-progress 23.

The control device 4 is connected to the bag gripper 1 by the connection member 5. After the bag gripper 1 is pressed against the workpiece 6 by the drive of the robot arm 18, the control device 4 applies a first electric signal to the bag gripper 1 to increase the viscosity of the magnetorheological fluid 8 in the bag body 2, thereby hardening the bag body 2. As a result, the bag gripper 1 hardens to imitate the shape of the head of the workpiece 6, grips the workpiece 6, and plays the role of a flathead screwdriver. Then, the hand part 19 is rotated up or down in accordance with the screw pitch of the workpiece 6, so that the workpiece 6 can be inserted and removed from the workpiece 23. In addition, the control device 4 applies a second electric signal to the bag gripper 1 to restore the viscosity of the magnetorheological fluid 8 in the bag body 2, thereby softening the bag body 2. This softening of the bag body 2 causes the bag gripper 1 to release its grip on the workpiece 6.

Next, the legged robot system according to the first embodiment will be described. FIG. 9 is a schematic side view of the legged robot system. In the legged robot system, the bag gripper 1 is disposed at each leg tip of the legged robot 24 and transmits leg force to the ground 25. The control device 4 is attached to the body of the legged robot 24 and controls each bag gripper 1 via the connection member 5. As the legged robot system walks, the bag gripper 1 is pressed against the ground 25, and then the control device 4 applies a first electrical signal to the bag gripper 1 to harden the bag body 2. This hardening of the bag body 2 causes the bag gripper 1 to grip the ground 25. As the legged robot system walks, the bag gripper 1 leaves the ground 25, and then the control device 4 applies a second electrical signal to the bag gripper 1 to soften the bag body 2. In the example shown in FIG. 9, the bag body 2 of the bag gripper 1 hardens to conform to the shape of the ground 25 and grips the ground 25, allowing for more stable running compared to when the bag gripper 1 is not attached to the tip of the leg of the leg robot 24 and the leg robot 24 is in direct contact with the ground 25.

In the example of Figure 9, the legged robot 24 has four legs, but this is not limited to this, and the bag gripper 1 may be attached to the tip of each leg of a two-legged or six-legged robot.

Second Embodiment
Next, a second embodiment of the present disclosure will be described. Note that the same components as those in the first embodiment are given the same reference numerals, and the description will be omitted or simplified. Fig. 10 is a schematic vertical cross-sectional view of a bag gripper 26 in the second embodiment.

As shown in FIG. 10, the bag gripper 26 in the second embodiment includes a bag body 2, as in the first embodiment, and maintains the shape of the bag body 2 by magnetic force. The filling inside the bag body 2 in the second embodiment is magnetic powder 27, unlike the first embodiment. The magnetic powder 27 is an example of a hardenable medium of the present disclosure.

It is desirable that the magnetic powder 27 has high fluidity so that after the bag body 2 softens, the tubular member 9 can push aside the magnetic powder 27 by the elastic force of the tubular member side elastic element 14 and move to the tip side of the bag body 2 as far as possible. The magnetic powder 27 having such fluidity is, for example, a spherical powder. It is desirable that the magnetic powder 27 is a material with low coercivity and high magnetic permeability, for example, a soft iron ball with a diameter of 1 mm.

The shape of the tip of the tubular member 9 has a constant diameter in the example of FIG. 10, but is not limited to this, and may be, for example, a tapered shape that becomes thinner toward the tip. In this case, the tubular member 9 will be able to push aside the magnetic powder 27 more easily, but if the tubular member 9 is tapered and the magnet 11 is also tapered in a similar manner, the magnetic force at the tip of the tubular member 9 will decrease when the magnet 11 is inserted up to the tip of the tubular member 9, and the force that maintains the shape of the bag body 2 will decrease.

In the example of FIG. 10, the filling medium other than the magnetic powder 27 filled in the bag body 2 is air, but is not limited thereto. Any fluid that does not damage the bag body 2, the base member 7, the cylindrical member 9, the seal member 10, or the magnetic powder 27 may be used, for example, nitrogen gas or silicone oil. In addition, by using a fluid with an anti-rust effect such as an anti-rust oil as a filling medium other than the magnetic powder 27, oxidation of the cylindrical member 9 or the magnetic powder 27 can be suppressed. When the same fluid as the ambient environment in which the bag gripper 26 operates is used as a filling medium other than the magnetic powder 27, the sealing between the bag body 2 and the base member 7 and the sealing by the seal member 10 between the base member 7 and the cylindrical member 9 are not required to be watertight or airtight, unlike the first embodiment, and it is sufficient to ensure that the magnetic powder 27 does not leak out. On the other hand, if a fluid different from the surrounding environment in which the bag gripper 26 operates is used as a filling medium other than the magnetic powder 27, the seal between the bag body 2 and the base member 7, and the seal between the base member 7 and the cylindrical member 9 by the seal member 10 must be airtight or watertight.

Third Embodiment
Next, a third embodiment of the present disclosure will be described. Note that the same components as those in the first embodiment are given the same reference numerals, and the description will be omitted or simplified. Fig. 11 is a schematic vertical cross-sectional view of a bag gripper 28 in the third embodiment.

In the bag gripper 28 in the third embodiment, a fluid is sealed inside the bag body 2 while maintaining watertightness, as in the first embodiment, but the substance sealed inside the bag body 2 in the third embodiment is an electrorheological fluid 29, unlike the first embodiment. The electrorheological fluid 29 is an example of a hardening medium of the present disclosure. In addition, the configuration corresponding to the cylindrical member 9 and magnet 11 in the first embodiment is 16 high-voltage electrodes 31 in the third embodiment, and the configuration corresponding to the cylindrical member side elastic element 14 in the first embodiment is a high-voltage electrode side elastic element 32 in the third embodiment. The high-voltage electrode 31 constitutes the hardening portion of the third embodiment. The high-voltage electrode 31 is made of iron and has a cylindrical shape. No insulating film is formed on the surface of the high-voltage electrode 31. The high-voltage electrode side elastic element 32 is made of a spring, like the cylindrical member side elastic element 14.

The base end of the high-voltage electrode 31 (the end connected to the high-voltage electrode-side elastic element 32) has a protrusion similar to that of the cylindrical member 9 in the first embodiment, so that the high-voltage electrode 31 does not fall off from the base member 7 to the bag body 2 side. It is preferable that the interval between the high-voltage electrodes 31 is narrow within a range where the insulation distance can be maintained, in that a high electric field strength can be obtained with a low voltage. As in the first embodiment, the high-voltage electrode 31 is allowed to have a slight inclination due to the elasticity of the seal member 10. The base member 7 is configured so that the high-voltage electrode 31 can move within the communication hole of the base member 7 while the watertightness of the bag body 2 is maintained by the seal member 10. As in the first embodiment, a force acts on the high-voltage electrode 31 in a direction toward the central axis of the bag body 2 due to the electrostatic force generated between the high-voltage electrodes 31. This force acting in a direction toward the central axis of the bag body 2 has the effect of preferentially hardening the electrorheological fluid 29 in the vicinity of the workpiece gripped near the central axis of the bag body 2, and also acts as a gripping force for the workpiece. However, in the third embodiment, it is required that the high-voltage electrodes 31 be able to maintain a distance between each other that is equal to or greater than the insulation distance, even if the high-voltage electrodes 31 are tilted to their maximum angle.

Although the seal member 10 is permitted to be slightly inclined with respect to the high voltage electrode 31, even if the seal member 10 is configured not to be inclined with respect to the high voltage electrode 31, the bag gripper 28 has a gripping performance.

The housing 3, base member 7, seal member 10, and guide mechanism 16 are required to have high insulation resistance and dielectric strength that will not be broken down by the high voltage applied to the high voltage electrode 31. In the area on the opposite side of the bag body 2 across the base member 7, the guide mechanism 16 acts as an insulating plate to provide insulation between adjacent high voltage electrodes 31.

The connection member 5 electrically connects the control device 4 and the high-voltage electrode 31. The connection member 5 is an electric wire, as in the first embodiment, but it is preferable that it is capable of withstanding high voltages. However, if the high-voltage generating circuit of the control device 4 is installed inside the bag gripper 28, the connection member 5 does not need to be capable of withstanding high voltages. Also, if the control device 4 is installed inside the bag gripper 28, the connection member 5 does not need to be installed.

The control device 4 controls the bag gripper 28 in the same manner as in the first embodiment. However, unlike the first embodiment, the control device 4 in the third embodiment applies a high voltage to the high-voltage electrode 31 of the bag gripper 28 via the connection member 5 to harden the bag body 2 by increasing the viscosity of the electrorheological fluid 29 in the bag body 2. This hardens the bag body 2 while encasing the workpiece, and as a result, the bag gripper 28 can grip the workpiece. The control device 4 also stops applying the high voltage to the high-voltage electrode 31 to soften the bag body 2 by reducing the viscosity of the electrorheological fluid 29 in the bag body 2. This softening of the bag body 2 causes the bag gripper 28 to release the grip of the workpiece.

The number of high-voltage electrodes 31 is not limited to 16, and may be any number as long as the electric field lines sufficiently penetrate the electrorheological fluid 29. The higher the electric field strength generated between the high-voltage electrodes 31, the more the viscosity of the electrorheological fluid 29 can be increased, for example, 2 kV/mm.

Fig. 12 is a schematic cross-sectional view of bag gripper 28 in the third embodiment taken along line B-B in Fig. 11. In Fig. 12, 31a is the cathode of high-voltage electrode 31, 31b is the anode of high-voltage electrode 31, and 33 is the electric field lines generated by high-voltage electrode 31. When a high voltage is applied to high-voltage electrode 31, electric field lines 33 penetrate electrorheological fluid 29, thereby increasing the viscosity of electrorheological fluid 29.

The arrangement of the cathode 31a and the anode 31b of the high-voltage electrode 31 is not limited to the example shown in FIG. 12, and may be, for example, an arrangement in which the position of the anode 31a and the position of the cathode 31b in FIG. 12 are interchanged. The high-voltage electrode 31 is an iron bar in the example shown in FIG. 12, but is not limited to this, and may be, for example, a resin bar on which a conductive film is formed by evaporating metal on its surface. Also, a single high-voltage electrode 31 may have a plurality of conductive films formed at a distance from each other, with some of the conductive films serving as anodes and the remaining conductive films serving as cathodes. The shape of the high-voltage electrode 31 is a cylinder in the example shown in FIG. 12, but is not limited to this, and may be, for example, a hexagonal prism or a cross prism. However, the smaller the gap between the high-voltage electrodes 31, the higher the viscosity of the electrorheological fluid 29 can be. In the example of Figure 12, the high-voltage electrode 31 is an iron rod with no coating on its surface, but this is not limited to this and an insulating film may be applied to the surface. By forming the insulating film, it is possible to prevent short circuits even if the high-voltage electrodes 31 come into contact with each other.

Fourth Embodiment
Next, a fourth embodiment of the present disclosure will be described. Note that the same components as those in the third embodiment are given the same reference numerals, and the description will be omitted or simplified. Fig. 13 is a schematic vertical cross-sectional view of a bag gripper 34 in the fourth embodiment.

As shown in FIG. 13, the bag gripper 34 in the fourth embodiment includes a bag body 2, as in the third embodiment, and maintains the shape of the bag body 2 by electrostatic force. Unlike the third embodiment, the filling inside the bag body 2 in the fourth embodiment is a dielectric powder 35. The dielectric powder 35 is an example of a hardenable medium of the present disclosure.

It is desirable that the dielectric powder 35 has high fluidity so that after the bag body 2 softens, the high-voltage electrode 31 can push the dielectric powder 35 aside by the elastic force of the high-voltage electrode side elastic element 32 and move to the maximum extent toward the tip side of the bag body 2. The dielectric powder 35 having such fluidity is, for example, a spherical powder. It is desirable that the dielectric powder 35 is a material with a high dielectric constant, for example, an alumina sphere with a diameter of 1 mm.

In the third embodiment, the inside of the bag body 2 is filled with the electrorheological fluid 29, so that the electrorheological fluid 29 functions as an insulating oil for the high-voltage electrode 31 inside the bag body 2. However, in the fourth embodiment, unlike the third embodiment, the filling medium other than the dielectric powder 35 filled in the bag body 2 is air, so that the inside of the bag body 2 is air-insulated from the high-voltage electrode 31, and the insulating property tends to be lower than that of the third embodiment. Therefore, the maximum allowable value of the electric field strength that can be applied between the high-voltage electrodes 31 tends to be more limited than that of the third embodiment. When the voltage applied to the high-voltage electrode 31 is particularly high, it is desirable that there be no protrusions on the surface of the high-voltage electrode 31 in order to prevent the occurrence of corona discharge. The shape of the tip end (the end opposite the base end) of the high-voltage electrode 31 has a constant diameter in the example of FIG. 13, but is not limited to this, and may be a tapered shape that becomes thinner toward the tip, for example. In this case, the high-voltage electrode 31 is more likely to push aside the dielectric powder 35, but the electrostatic force at the tip end when a high voltage is applied to the high-voltage electrode 31 is reduced, and the force that maintains the shape of the bag body 2 is reduced.

As in the third embodiment, in the area on the opposite side of the bag body 2 across the base member 7, the guide mechanism 16 acts as an insulating plate to provide insulation between adjacent high-voltage electrodes 31.

In the example of FIG. 13, the filling medium other than the dielectric powder 35 filled in the bag body 2 is air, but is not limited thereto, and may be any insulating fluid that does not damage the bag body 2, the base member 7, the seal member 10, the high-voltage electrode 31, or the dielectric powder 35, for example, nitrogen gas or silicone oil. When the same fluid as the surrounding environment in which the bag gripper 34 operates is used as a filling medium other than the dielectric powder 35, unlike the third embodiment, the sealing between the bag body 2 and the base member 7 and the sealing by the seal member 10 between the base member 7 and the high-voltage electrode 31 do not require watertightness or airtightness, and it is sufficient to ensure that the dielectric powder 35 does not leak. However, in a dusty environment, a high humidity environment, or an surrounding environment containing salt or harmful gases, sufficient watertightness or airtightness is required because there is a risk of the insulation property being reduced. In addition, even if the dielectric powder 35 is a hygroscopic substance, sufficient watertightness or airtightness is required. On the other hand, when a fluid different from the surrounding environment in which the bag gripper 34 operates is used as a filling medium other than the dielectric powder 35, the seal between the bag body 2 and the base member 7, and the seal by the seal member 10 between the base member 7 and the high-voltage electrode 31 must be airtight or watertight. By using a highly insulating fluid as a filling medium other than the dielectric powder 35, a higher voltage can be applied to the high-voltage electrode 31. In addition, by using a fluid with anti-rust properties such as anti-rust oil as a filling medium other than the dielectric powder 35, oxidation of the high-voltage electrode 31 or the dielectric powder 35 can be suppressed.

Fifth Embodiment
Next, a fifth embodiment of the present disclosure will be described. Note that the same components as those in the first embodiment are given the same reference numerals, and the description will be omitted or simplified. Fig. 14 is a schematic vertical cross-sectional view of a bag gripper 36 in the fifth embodiment.

As shown in FIG. 14, the bag gripper 36 in the fifth embodiment has a magnetorheological fluid 8 sealed inside the bag body 2, similar to the first embodiment, but unlike the first embodiment, the actuator that moves the magnet 11 is not a single linear actuator 13, but multiple rotary actuators 37. The rotary actuators 37 are provided for each magnet 11 and fixed to the housing 3.

The bag gripper 36 does not have a magnet fixing member 12 or magnet-side elastic element 15, and the magnet 11 is fixed directly to the wire 38 of the rotary actuator 37, for example, by adhesive or heat shrink tubing. The magnet fixing member 12 may be disposed between the magnet 11 and the wire 38, but in this case, when the magnet 11 moves to the maximum extent toward the tip of the tubular member 9, the tip of the magnet 11 moves away from the tip of the tubular member 9 by the length of the magnet fixing member 12, which tends to make it difficult for the magnetic field lines to pass to the tip side of the bag body 2.

The wire 38 is formed in a linear shape. The wire 38 is looped around a driving pulley 39 fixed to the driving shaft of the rotary actuator 37 and a driven pulley 40 fixed to the inside of the closed end of the cylindrical member 9. When the axial distance between the driving pulley 39 and the driven pulley 40 changes as a result of the cylindrical member 9 being pushed in by the workpiece, the wire 38 loosens to absorb the change. It is desirable to design the length of the wire 38 so that the cylindrical member 9 is not subjected to a magnetic force as much as possible even if the cylindrical member 9 is pushed in to the rotary actuator 37 by the workpiece when the magnet 11 moves to the rotary actuator 37 side to the maximum extent. In the example of FIG. 14, a linear wire 38 is used, but a belt may be used instead of the wire 38.

The driving pulley 39 rotates when driven by the rotary actuator 37. The driven pulley 40 rotates passively due to the movement of the wire 38 accompanying the rotation of the driving pulley 39. When the rotary actuator 37 is driven, the magnet 11 moves linearly via the wire 38. A smaller diameter of the driven pulley 40 allows the magnet 11 to move linearly further to the tip of the bag body 2, but a smaller diameter of the driven pulley 40 tends to increase the frictional force when the wire 38 moves. Note that in the example of FIG. 14, a rotating driven pulley 40 is used, but this is not limited to this, and a hook mechanism, for example, may be used instead of the driven pulley 40.

The rotary actuator wiring 41 electrically connects the connection member 5 and the rotary actuator 37. The control device 4 drives each rotary actuator 37 via the connection member 5 and the rotary actuator wiring 41. Note that if the control device 4 is installed inside the bag gripper 36, the connection member 5 does not need to be installed.

When the magnetorheological fluid 8 is made highly viscous to grip the workpiece with the bag gripper 36, the control device 4 applies a first electrical signal to the rotary actuator 37 to rotate the drive pulley 39 in a first direction to move the wire 38. When the magnet 11 reaches the closed end inside the cylindrical member 9, the control device 4 stops the drive pulley 39. When the magnet 11 reaches the closed end inside the cylindrical member 9, the viscosity of the magnetorheological fluid 8 increases, and the bag gripper 36 grips the workpiece 6.

On the other hand, when the viscosity of the magnetorheological fluid 8 is to be reduced to release the workpiece, the control device 4 applies a second electrical signal to the rotary actuator 37 to rotate the drive pulley 39 in a second direction opposite to the first direction, thereby moving the wire 38. When the magnet 11 is completely removed from the cylindrical member 9, the control device 4 stops the drive pulley 39. When the magnet 11 is removed from the cylindrical member 9, the viscosity of the magnetorheological fluid 8 is reduced, and the grip on the workpiece 6 is released.

Sixth Embodiment
Next, a sixth embodiment of the present disclosure will be described. Note that the same reference numerals are used for the same configurations as those in the first embodiment, and the description will be omitted or simplified. Fig. 15 is a schematic vertical cross-sectional view of a bag gripper 42 in the sixth embodiment.

In the bag gripper 42 in the sixth embodiment, as in the first embodiment, a fluid is sealed inside the bag body 2 while maintaining watertightness, but unlike the first embodiment, the substance sealed inside the bag body 2 in the sixth embodiment is an aqueous sodium acetate solution 43. The aqueous sodium acetate solution 43 is an example of a hardenable medium of the present disclosure. In addition, the configuration corresponding to the cylindrical member 9 and magnet 11 in the first embodiment is 16 heat pipes 44 in the sixth embodiment, and the configuration corresponding to the cylindrical member side elastic element 14 in the first embodiment is a heat pipe side elastic element 45 in the sixth embodiment. The heat pipe side elastic element 45 is composed of a spring like the cylindrical member side elastic element 14, and connects the guide mechanism 16 and the heat pipe 44.

The heat pipe 44 is made of iron and is cylindrical. The heat pipe 44 is inserted into a communication hole in the base member 7. The space between the base member 7 and the heat pipe 44 is sealed with a seal member 10 so that the communication hole is watertight. Inside the heat pipe 44, there are a hot fluid flow path 48 through which hot fluid 46 flows, and a cold fluid flow path 49 through which cold fluid 47 flows. The hot fluid flow path 48 and the cold fluid flow path 49 are each formed in a U-shape.

One end of a hot fluid supply pipe 50 is connected to the inlet end of the hot fluid flow path 48, and one end of a hot fluid discharge pipe 51 is connected to the outlet end. One end of a cold fluid supply pipe 52 is connected to the inlet end of the cold fluid flow path 49, and one end of a cold fluid discharge pipe 53 is connected to the outlet end. The hot fluid 46 is stored in a hot fluid tank 54 and is heated by a heater 56 attached to the hot fluid tank 54. The hot fluid 46 is maintained at a temperature equal to or higher than the melting point of the sodium acetate aqueous solution 43, for example, 90°C. The cold fluid 47 is stored in a cold fluid tank 55 and is cooled by a cooler 57 attached to the cold fluid tank 55. The cold fluid 47 is maintained at a temperature equal to or lower than the melting point of the sodium acetate aqueous solution 43, for example, 20°C. The heater 56 is, for example, an electric heater. The cooler 57 is, for example, a cold water chiller.

The other end of the hot fluid supply pipe 50 is connected to the bottom of the hot fluid tank 54 via a hot fluid valve 58 and a hot fluid pump 60. The other end of the cold fluid supply pipe 52 is connected to the bottom of the cold fluid tank 55 via a cold fluid valve 59 and a cold fluid pump 61. The other end of the hot fluid discharge pipe 51 is connected to the top of the hot fluid tank 54. The other end of the cold fluid discharge pipe 53 is connected to the top of the cold fluid tank 55. When the hot fluid valve 58 is opened while the cold fluid valve 59 is closed and the hot fluid pump 60 is driven, the hot fluid 46 circulates and the heat pipe 44 is heated. When the hot fluid valve 58 is closed while the cold fluid valve 59 is opened and the cold fluid pump 61 is driven, the cold fluid 47 circulates and the heat pipe 44 is cooled.

The hardening trigger mechanism 65 is composed of a hardening trigger driver 62 and a hardening trigger plate 63. The hardening trigger driver 62 is attached to the housing 3. The hardening trigger driver 62 is, for example, a solenoid, an electric or pneumatic linear actuator, or a rotary actuator having a cam mechanism on the output shaft. The hardening trigger plate 63 is supported by a hardening trigger plate support member 64 attached to the base member 7. The hardening trigger plate 63 is a metal plate supported by the hardening trigger plate support member 64 in a deflected state. When the hardening trigger driver 62 is driven via the connection member 5 under the control of the control device 4, the hardening trigger plate 63 undergoes snap buckling.

By controlling the control device 4, the hot fluid valve 58 and the hot fluid pump 60 are driven via the connection member 5, and the hot fluid 46 is caused to flow through the hot fluid flow path 48, so that the temperature of the sodium acetate solution 43 becomes equal to or higher than the melting point and becomes liquid. Then, by controlling the control device 4, the hot fluid valve 58 and the hot fluid pump 60 are stopped to stop the flow of the hot fluid 46, while the cold fluid valve 59 and the cold fluid pump 61 are driven to cause the cold fluid 47 to flow through the cold fluid flow path 49, so that the sodium acetate solution 43 is cooled to below the freezing point, and then the cold fluid valve 59 and the cold fluid pump 61 are stopped to stop the flow of the cold fluid 47. At this time, the sodium acetate solution 43 remains liquid due to the supercooling phenomenon. In this state, the bag body 2 is pressed against the workpiece, so that the workpiece is wrapped in the bag body 2.

Next, under the control of the control device 4, the hardening trigger driver 62 is driven via the connection member 5, causing the hardening trigger plate 63 to jump and buckle, thereby applying an impact to the sodium acetate aqueous solution 43. The hot ice phenomenon caused by this impact rapidly hardens the sodium acetate aqueous solution 43, hardening the bag body 2. As a result, the bag body 2 hardens while encasing the workpiece, and as a result, the bag gripper 42 can grip the workpiece. In other words, the heat pipe 44 and the hardening trigger mechanism 65 constitute the hardening section of the sixth embodiment. Note that the impact applied when the bag body 2 is pressed against the workpiece is kept to a level that does not cause the sodium acetate aqueous solution 43 to cause the hot ice phenomenon.

By controlling the control device 4, the hot fluid valve 58 and the hot fluid pump 60 are driven and the hot fluid 46 is caused to flow through the hot fluid flow path 48, causing the temperature of the sodium acetate aqueous solution 43 to rise above its melting point, softening the bag body 2 and releasing the workpiece.

Here, the sodium acetate aqueous solution 43 is prepared so that the mass ratio is, for example, 10 parts sodium acetate trihydrate and 1 part pure water. In order to shorten the time required for the bag body 2 to harden, the sodium acetate aqueous solution 43, which is prone to supercooling, is used as the hardening medium to be sealed inside the bag body 2. The hardening medium is not limited to sodium acetate trihydrate, and any fluid that is prone to supercooling can be used. An example of a fluid that is prone to supercooling is sodium thiosulfate pentahydrate. The temperatures of the hot fluid 46 and the cold fluid 47 are set according to the melting point of the hardening medium and the heat resistance temperature of the workpiece. If the application does not require a long time for the bag body 2 to harden, the hardening medium may be a fluid that is unlikely to cause supercooling, such as pure water or liquid metal. In this case, the hardening trigger mechanism 65 does not need to be provided.

When a hardening medium that is solid at room temperature is sealed in the bag body 2, the hot fluid valve 58 and the hot fluid pump 60 are driven under the control of the control device 4, and the hot fluid 46 is caused to flow through the hot fluid flow path 48, so that the hardening medium becomes liquid at a temperature above the melting point. After that, the workpiece is pressed against the bag body 2, and the workpiece is wrapped in the bag body 2. Next, under the control of the control device 4, the hot fluid valve 58 and the hot fluid pump 60 are stopped to stop the flow of the hot fluid 46, while the cold fluid valve 59 and the cold fluid pump 61 are driven to cause the cold fluid 47 to flow through the cold fluid flow path 49, thereby cooling the hardening medium to below the freezing point, and when the bag body 2 hardens, the cold fluid valve 59 and the cold fluid pump 61 are stopped to stop the flow of the cold fluid 47. As a result, the bag body 2 hardens in a state in which it wraps the workpiece, and the bag gripper 42 can grip the workpiece. To release the workpiece, the hot fluid valve 58 and the hot fluid pump 60 are driven under the control of the control device 4 to cause the hot fluid 46 to flow through the hot fluid flow path 48, so that the hardenable medium reaches a temperature above its melting point and becomes liquid, causing the bag gripper 42 to release the workpiece.

When sealing the hardening medium, which is liquid at room temperature, in the bag body 2, first the workpiece is pressed against the bag body 2 so that the workpiece is wrapped in the bag body 2. Then, under the control of the control device 4, the cold fluid valve 59 and the cold fluid pump 61 are driven, and the cold fluid 47 is caused to flow through the cold fluid flow path 49, thereby cooling the hardening medium to below the freezing point and hardening the bag body 2. As a result, the bag body 2 hardens while wrapping the workpiece, and as a result, the bag gripper 42 can grip the workpiece. To release the workpiece, under the control of the control device 4, the cold fluid valve 59 and the cold fluid pump 61 are stopped to stop the flow of the cold fluid 47, while the hot fluid valve 58 and the hot fluid pump 60 are driven to cause the hot fluid 46 to flow through the hot fluid flow path 48, so that the hardening medium becomes liquid at a temperature above the melting point. As a result, the bag gripper 42 releases the workpiece.

In addition, the flow paths in the heat pipe 44 are arranged for each of the hot fluid 46 and the cold fluid 47, but this is not limited to the above, and only one flow path shared by the hot fluid 46 and the cold fluid 47 may be arranged, and the fluid to be passed may be switched by a switching valve provided on the upstream side and downstream side of the heat pipe 44. The heat pipe 44 is made of iron, but is not limited to this, and may be made of, for example, aluminum or copper. A material with a high thermal conductivity is preferable because it can change the temperature of the hardenable medium more quickly. The heat pipe 44 is cylindrical, but is not limited to this, and may be, for example, a hexagonal column. The hot fluid flow path 48 and the cold fluid flow path 49 are each formed in a U-shape, but are not limited to this, and may be formed in a shape of a U-shaped tube wound in a spiral. It is preferable that the surface area of the hot fluid 46 and the cold fluid 47 in contact with the heat pipe 44 and the surface area of the heat pipe 44 in contact with the hardenable medium are as large as possible, because the temperature of the hardenable medium can be changed more quickly.

[Modification of the embodiment]
Needless to say, the present disclosure is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the present disclosure. Furthermore, the above embodiments and the modifications described below may be combined in any way as long as they function normally.

For example, the bag gripper 26 in the second embodiment, the bag gripper 28 in the third embodiment, the bag gripper 34 in the fourth embodiment, and the bag gripper 36 in the fifth embodiment can be applied to the gripping system, jig system, and legged robot system exemplified in the first embodiment.

The membrane bag composite of the present disclosure has the effect of stably gripping or manipulating a wider variety of workpieces by increasing the deformable capacity of the bag body, and can be applied to factory automation applications such as high-mix low-volume production, as well as service robots such as delivery robots. In addition, the membrane bag composite of the present disclosure can be applied to exploration robots in water or in places with thin air by increasing the watertightness or airtightness of the bag body.

1, 26, 28, 34, 36, 42 Bag gripper 2 Bag body 3 Housing 4 Control device 5 Connection member 6 Work 7 Base member 8 Magnetorheological fluid 9 Cylindrical member 10 Sealing member 11 Magnet 11a N pole 11b S pole 12 Magnet fixing member 13 Linear actuator 13A Main body 13B Moving element 14 Cylindrical member side elastic element 15 Magnet side elastic element 16 Guide mechanism 17 Magnetic field lines 18 Robot arm 19 Hand 20 Robot support base 21 Two-finger gripper 22 Two-finger gripper claw 23 Work in progress 24 Legged robot 25 Ground 27 Magnetic powder 29 Electrorheological fluid 30 High-voltage wire 31 High-voltage electrode 31a Cathode 31b anode 32 high voltage electrode side elastic element 33 electric field lines 35 dielectric powder 37 rotary actuator 38 wire 39 driving pulley 40 driven pulley 41 rotary actuator wiring 43 sodium acetate aqueous solution 44 heat pipe 45 heat pipe side elastic element 46 hot fluid 47 cold fluid 48 hot fluid flow path 49 cold fluid flow path 50 hot fluid supply pipe 51 hot fluid discharge pipe 52 cold fluid supply pipe 53 cold fluid discharge pipe 54 hot fluid tank 55 cold fluid tank 56 heater 57 cooler 58 hot fluid valve 59 cold fluid valve 60 hot fluid pump 61 cold fluid pump 62 hardening trigger driver 63 hardening trigger plate 64 hardening trigger plate support member 65 hardening trigger mechanism

Claims (11)

A flexible bag having an opening, the bag being filled with a hardenable medium made of a fluid or a powder;
a base member disposed to close the opening of the bag body, the base member having a communication hole that communicates between the inside and the outside of the bag body;
a hardened portion inserted into the communication hole so as to be movable in the direction of a central axis of the communication hole,
The hardening unit hardens the hardenable medium to hold the bag body in a desired shape.
Membrane bag complex. The bag body conforms to the shape of the workpiece by a pressing force that presses the workpiece against the bag body.
The membrane bag complex according to claim 1. The curable medium has magnetic or dielectric properties;
The hardening unit hardens the hardenable medium using magnetic or dielectric properties.
The membrane bag complex according to claim 1 or 2. The hardenable medium is magnetic;
The hardening portion includes a magnet.
The membrane bag complex according to claim 3. the hardenable medium is a magnetic fluid;
The base member is configured so that the hardening portion can move while the watertightness or airtightness of the bag body is maintained.
The membrane bag complex according to claim 4. The hardenable medium is a magnetic powder.
The membrane bag complex according to claim 4. The curable medium has dielectric properties;
The hardening portion includes an electrode.
The membrane bag complex according to claim 3. the hardenable medium is an electrorheological fluid;
The base member is configured so that the hardening portion can move while the watertightness or airtightness of the bag body is maintained.
The membrane bag complex according to claim 7. The hardenable medium is a dielectric powder.
The membrane bag complex according to claim 7. The hardenable medium is a fluid that hardens upon a decrease in temperature;
The base member is configured so that the hardening portion is movable while the watertightness or airtightness of the bag body is maintained,
The hardening unit hardens the hardenable medium by lowering the temperature of the hardenable medium.
The membrane bag complex according to claim 2. The hardening unit hardens the hardenable medium by applying an impact to the hardenable medium in a supercooled state.
The membrane bag complex according to claim 10.