JPS6198164A - Pressure generator - Google Patents

Abstract

PURPOSE:To facilitate the generation of a very low pressure, the control thereof and to reduce the size and the weight of a pressure generator by using gel of organic polymer which shrinks and expands in response to an applied voltage as a pressure generator medium, and controlling the voltage applied directly to the medium. CONSTITUTION:A variable volume vessel 15 made of a semispherical rubber elastic material is hermeticallysecured to an electric insulating base 13 by providing a holding wall 16 on the outer periphery. Gel 11 of polyacrylic amide is impregnated with aqueous 30%-acetone solution, and contained in the vessel, a pair of electrodes 12 for forming an electric field therein are disposed fixedly to the base 13 to construct a pressure generator. Thus, when the gel 11 is expanded, a voltage is applied to the electrodes 12 while a load is applied, thereby gradually increasing. Then, the gel 11 and the vessel 15 are shrinked. When the applied voltage is, on the contrary, decreased, it is gradually expanded. The generated pressure can be finely controlled by controlling the applied voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a pressure generating device capable of controlling the minute pressure generated, and in particular to a pressure generating device that is attached to the tip of a robot's hand or finger and generates a minute pressing force to control the pressure generated by an object. Conventional configuration of pressure generating device suitable for grasping and its problems Currently, when an object is grasped by a robot's hand or fingers, the object to be grasped is limited to an object that has a certain degree of mechanical strength. The reason for this is that the object is grasped by determining the position of the robot's hand or fingers when grasping the object, so variations in the position determination of the hand or fingers cannot be avoided, and this variation is within the allowable range. This is because the object must have the mechanical strength to withstand the stress even when it is grasped. Generally, measures are taken to prevent damage due to mechanical stress by interposing a flexible or elastic material such as rubber between the robot's hand or fingers and the object. However, it was difficult to grasp objects with low mechanical strength such as glass containers, or objects with different shapes without damaging them one after another.

Therefore, when grasping an object with a robot's hand or fingers, the position of the hand or fingers is fixed at the position immediately before touching the object, and then a small pressing force is generated at the tip of the hand or fingers. Preferably, the object is grasped by the generator forcing the hand or fingers against the object. Hydraulic pump type pressure generating devices are generally well known as conventional pressure generating devices, but such devices are difficult to miniaturize and reduce in weight, and are only capable of gripping and holding easily breakable objects such as glass containers. It is difficult to generate such a minute pressure, and it is also extremely difficult to control the generation of that minute pressure.

Purpose of the Invention The present invention uses an organic polymer gel that contracts or expands in response to applied voltage as a pressure-generating medium.
It is an object of the present invention to provide a pressure generating device that can easily generate and control minute pressure by controlling the voltage directly applied to the pressure generating medium, and can be made smaller and lighter.

Another object of the present invention is to provide a pressure generating device that can be attached to the tip of a robot's hand or finger and can safely and reliably grasp even objects with relatively low mechanical strength, such as glass containers.

Composition of the Invention The pressure generating device of the present invention includes an electrically insulating base, a variable volume container sealed on the electrically insulating base, and a solvent-impregnated container that contracts in response to an applied voltage. or a pressure generating device comprising a gel body of an organic polymer that expands, and having at least one pair of electrodes extending into the gel body and for forming an electric field within the gel body. An example of an organic polymer gel that contracts or expands depending on the applied voltage is a polyacrylamide gel. When such a gel body is sufficiently impregnated with an acetone aqueous solution, its volume gradually shrinks as the acetone concentration in the acetone aqueous solution changes, and reaches a minimum at a constant concentration, for example, 42% acetone aqueous solution.
Thereafter, the volume tends to increase as the acetone concentration increases. Furthermore, when a polyacrylamide gel body is impregnated with an aqueous solution of a certain concentration of acetone, it maintains a volume corresponding to the concentration, but when an electrode is inserted into this gel body and a voltage is applied, an electric field is created inside the gel body. The volume decreases as the voltage increases, and the volume becomes the minimum at about 2V. For this reason, the volume of the polyacrylamide gel can be freely controlled by impregnating an aqueous solution with a fixed acetone concentration and changing the strength of the electric field formed within the gel, that is, the applied voltage. The insulating substrate used in the present invention can be made of any material, such as a synthetic resin plate, by skillfully utilizing the gel properties of polyacrylamide.

In the pressure generating device of the present invention, in order to form an electric field within the gel body by applying a voltage, at least one pair of wi poles fixed to the insulating base and extending inside the gel body are provided.

As described above, the pressure generating device of the present invention encloses an organic polymer gel body that contracts or expands in response to applied voltage in a container whose volume can be changed in accordance with the contraction or expansion. Such a variable volume container may be formed by forming a membrane of a rubber-like elastic material into a bag shape, sealingly provided on an electrically insulating base, and enclosing the gel body therein. Further, the variable volume container can also be composed of a cylinder portion hermetically fixed on an electrically insulating base, and a piston portion having an outer end that slides airtight with the cylinder portion.

At this time, it is preferable to configure the closed outer end of the piston portion with an elastic membrane, since this can alleviate the impact on the object when the pressure generating device of the present invention is used to press or grip the object. - When the entire variable volume container is formed into a bag shape using the above-mentioned elastic film, the direction of the elastic film that contracts or expands in accordance with the contraction or expansion of the gel body in response to voltage application is kept as constant as possible; That is, it is preferable to provide a container holder on the outer periphery of the container in order to contract or expand the container in a direction perpendicular to the electrically insulating base.Description of Embodiments FIG. 1 shows an example of the pressure generating device of the present invention.

FIG. 1(a) is a vertical sectional view in a state where no voltage is applied, and FIG. 1(b) is a vertical sectional view in a state when the polyacrylamide gel body is contracted by voltage application. 0) is a perspective view of FIG. 1(a).

In FIGS. 1(A) to (e), 11 is a polyacrylamide gel body impregnated with a 30% acetone aqueous solution, and 12 is a pair of electrodes for forming an electric field within the gel body 11. This electrode is fixed to a disc-shaped electrically insulating base 13 made of phenolic resin, and is covered with a gel body.
extends inward. The electrode 12 is connected to an external connection terminal 14, and this connection is, of course, sealed. 15
is a variable volume container made of a substantially hemispherical rubber elastic body, for example, a film of ethylene-propylene rubber, and a retaining wall 16 is provided on the outer periphery of the container. The peripheral edge of the variable volume container made of the hemispherical rubber elastic membrane and the retaining wall 16 are tightly fixed to the electrically insulating base 13.

In the pressure generator of this example, the inner diameter of the retaining wall 16 was 10 m. When the gel body 11 is in an expanded state without applying the voltage shown in FIG. When the gel body 11 is in an expanded state as shown in FIG. When the applied voltage increases, the container 15 consisting of the gel body 11 and the elastic membrane surrounding it increases.
shrinks to the state shown in FIG. 1(b).

Conversely, when the applied voltage is decreased, the gel body 11 and container 15 gradually expand to the state shown in FIG. 1(a).

Therefore, the pressure generating device described above can minutely control the generated pressure by controlling the applied voltage.

Next, an example of use of the above pressure generating device will be described. First, when applying pressure to an external object, a voltage is applied to the pressure generating device, and the gel body 11 as shown in FIG.
and leave the container 15 in a deflated state. Next, the outer surface of the container 15 of the pressure generator in this state is brought close to the surface of a fixed external object to be pressed, and the pressure generator is fixed at that position. Then gradually reduce the voltage or bring it to zero. In this way, the pressure generating device enters the expanded state shown in Fig. 1 (-), presses the external object,
The magnitude of the pressing force at this time, when the pressure is applied, can be controlled by controlling the applied voltage to be reduced.

As can be seen from the above, if the pressure generating device of the present invention is attached to the tip of a finger of a robot hand, for example, and the applied voltage is controlled by electronic control, an object with low mechanical strength can be grasped completely and reliably. be able to.

Next, FIG. 2 shows another example of the pressure generating device of the present invention. FIG. 2(-) is a vertical sectional view in a state where no voltage is applied, and FIG. 2(b) is a vertical sectional view in a state when the polyacrylamide gel body is contracted by voltage application. This example is an example of a pressure generating device in which the variable volume container is composed of the aforementioned cylinder section and piston section, and the closed outer end is composed of an elastic membrane.

In FIGS. 2(-) and (b), 21 is a polyacrylamide gel body impregnated with a 25% acetone aqueous solution, and 9.22 is a pair of gel bodies for forming an electric field within the gel body 21. This electrode is fixed to a disc-shaped electrically insulating base 23 made of epoxy resin and extends inside the gel body 21. The electrode 22 is connected to an external connection terminal 24.
This connection is sealed.

Reference numeral 25 denotes an elastic membrane made of ethylene-propylene rubber, the peripheral edge of which is fixed to the upper part of the cylindrical piston part 26 to seal the piston part. 27 is a cylinder portion, and the piston portion 26 and cylinder portion 27 slide in an airtight manner. The lower end of the cylinder portion 27 is fixed to the insulating base 23. The piston section 26 and the cylinder section 27 are made of stainless steel.

In the pressure generating device of this example, the outer diameter of the piston portion 26 was 12+m, and the inner diameter was 8 m.

A total of 30 pressure generators shown in Fig. 2(a) were fixed close to each other in 5 rows x 6 columns on each hand of the robot hand (60 in both hands), and the pressure was applied to each of the pressure generators. Each external power supply providing the required voltage was separately computer controlled. First, the same voltage of 1.5 V was applied to all (60) pressure generators to cause the gel body 21 to contract. Then, as shown in FIG. 2(b), the piston portion 26 is slidably fitted into the cylinder portion 27 and is in a contracted state. Next, the robot hand is moved under computer control and placed in a circle (diameter 20 C1l) filled with standing water.
Place the palm of the robot hand near the side of the glass fishbowl. Next, the voltage applied to each pressure generator is gradually reduced by computer control, and the gel body 21 in each pressure generator is gradually expanded, so that the outer surface of the elastic membrane 25 of each pressure generator becomes like a fishbowl. When a suitable constant pressure is generated on the outer surface of the fishbowl,
The voltage of each pressure generator was fixed. Next, move the robot hand to another location while keeping the water surface of the fishbowl horizontal, and after leaving it stationary, increase all the voltages applied to each pressure generator to cause the gel body 21 to contract again. He released the goldfish bowl from the robot hand.

Effects of the Invention As described above, the pressure generating device according to the present invention has a simple configuration of a variable volume container in which a gel body of an organic polymer that contracts or expands according to the applied voltage is used to apply pressure to the gel body. By controlling the voltage, it is possible to delicately control the pressure acting on an external object.The pressure generator of the present invention can also be made smaller, lighter, and lower in cost, and is especially suitable for mounting on a robot hand. This has the effect of allowing objects with low mechanical strength and objects of various shapes to be grasped freely, completely and reliably.

[Brief explanation of the drawing]

FIG. 1(a) is a vertical cross-sectional view of the pressure generator of the present invention in a state where no voltage is applied, and FIG. 1(b) is a vertical cross-sectional view with a voltage applied. FIG. 2(e) is a perspective view of FIG. 1(, ), and FIG. 2(a) is a vertical sectional view of another pressure generating device of the present invention in a state where no voltage is applied. (b) is a vertical cross-sectional view with a voltage applied.0 11.21 is a gel body, 12.22 is an electrode, 13°23 is an electrically insulating base, 14.24 is an external connection terminal, 1 and 25 are elastic 16 is a holding wall, 26 is a piston portion, and 27 is a cylinder portion. Patent applicant Matsushita Electric Industrial Co., Ltd. 1-12 Figure 1 Figure 2 (b)

Claims (1)

[Scope of Claims] 1. An electrically insulating base; a variable volume container sealed on the electrically insulating base; a solvent-impregnated container sealed in the variable volume container that contracts or expands in response to applied voltage; A pressure generating device comprising a gel body of an organic polymer and comprising at least one pair of electrodes extending into the gel body and for forming an electric field within the gel body. 2. The pressure generating device according to claim 1, wherein the variable volume container is entirely made of an elastic membrane. 3. The pressure generating device according to claim 2, wherein a retaining wall is provided on the outer periphery of the variable volume container made entirely of an elastic membrane. 4. The pressure generating device according to claim 1, wherein the variable volume container comprises a cylinder part sealed and fixed on an electrically insulating base, and a piston part with a closed outer end that slides airtight with the cylinder part. 5. The pressure generating device according to claim 4, wherein the closed outer end of the piston portion is constituted by an elastic membrane. 6. The pressure generating device according to claim 1, wherein the organic polymer gel is a polyacrylamide gel.