KR102304559B1 - Soft gripper having active three dimensional structure, and manufacturing method thereof - Google Patents

Abstract

A pneumatically controlled pneumatic gripper is disclosed. The gripper includes: a chamber part having a negative pressure action space that is opened in a downward direction; a sucker extending radially from a lower portion of the chamber; It protrudes from the upper surface of the negative pressure action space, is located in the negative pressure action space, is provided as a gas bag, has elasticity that can expand and contract, expands to form a negative pressure in the negative pressure action space, and contracts to form a negative pressure in the negative pressure action space ridges to be removed; and a gas inlet and outlet penetrating through the gas bag of the ridge from the upper end of the chamber, allowing fluid to be injected into the gas bag so that the ridge expands, and sucking the fluid in the gas bag to contract the ridge. characterized in that

Description

Active three-dimensional adhesive structure and manufacturing method of soft gripper including same {SOFT GRIPPER HAVING ACTIVE THREE DIMENSIONAL STRUCTURE, AND MANUFACTURING METHOD THEREOF}

The present invention relates to a pneumatically controlled soft gripper, a method for manufacturing the same, and a method for transferring an article using the soft gripper, and more particularly, to a pneumatically controlled soft gripper capable of adhering to various surfaces, a method for manufacturing the same, and a method for transferring an article using the soft gripper it's about

Adsorption systems for transporting articles are widely used in various fields, such as semiconductor equipment, home appliance production, and medical supplies production.

In the adsorption system, a technique for generating adhesive force by inducing a negative pressure at the interface between the adsorption port of an elastic material and the object is used.

However, in most conventional adsorption systems, the method of inducing the negative pressure between the adsorption port and the object is a structure in which the adhesion between the adsorption port and the surface is made by applying a vertical pressure in the direction of the surface of the object from the top of the adsorption port to induce negative pressure, or It has a structure in which the adhesion between the adsorption sphere and the surface is made by forming a negative pressure in a manner that sucks the fluid from the inside of the sphere.

In such a conventional adsorption system, in the case of a method of forming a negative pressure by applying a vertical pressure, the negative pressure between the adsorption port and the surface is not sufficiently exerted, so the adhesive force is easily released during the transfer of the object, and there is a problem that the transfer of the object becomes difficult. , especially in a humid environment or in an underwater environment, when the negative pressure is formed, the liquid flows in and interferes with the negative pressure, so that the sucker chamber based on the negative pressure in a humid or underwater environment has a problem in that the adhesive force is significantly lowered.

In order to solve this problem, the present inventor has Korean Patent No. 10-1745803, and this Korean patent has improved the adhesion by the sucker by forming a ridge in the sucker that mimics the sucker of an octopus, and especially in a humid environment. . Although this registered patent also shows very good adhesion, vertical pressure from top to bottom was required to induce adhesion of the chorion to the inner wall of the sucker chamber and to induce decompression in the sucker chamber. There were restrictions on the shape and size of the sucker and the limited size of the chorion to ensure the contact of the ridges. This could act as a limitation of adhesion by the sucker chamber.

In addition, in the case of sucker chamber adhesion, detachment is not easy. For detachment, the pressure in the sucker chamber must be increased by twisting the sucker or lifting the contact surface of the sucker. Alternatively, a strong pulling force is applied between the sucker and the adherend, and the sucker is detached by applying more force than the maximum that the sucker can be attached to due to the pressure difference. However, these operations have a disadvantage in that the contact surface is damaged or a complex and difficult configuration is required for its operation.

That is, the conventional adsorption system has a limited adhesion target, it is difficult to exert sufficient negative pressure for stable adhesion, so it is difficult to transport a stable object, and it is difficult to use in various environments such as a dry environment and an underwater environment. There was a problem that it was difficult to use for pressure-sensitive products.

The present invention provides a new pneumatic controlled negative pressure adsorption method that can easily exhibit adhesion even in water, and can provide easy adsorption according to an easy negative pressure provision and easy desorption according to an easy negative pressure removal method.

SUMMARY OF THE INVENTION An object of the present invention is to provide a soft gripper capable of exhibiting and maintaining sufficient adhesion to various surfaces, and easily controlling attachment and detachment, a method for manufacturing the same, and a method for transferring an article using the soft gripper.

Another object of the present invention is to provide a soft gripper capable of exhibiting and maintaining sufficient adhesion in various environments, a method for manufacturing the same, and a method for transferring an article using the soft gripper.

Another object of the present invention is to provide a soft gripper capable of easily adhering to various surfaces and pressure-sensitive materials, a method for manufacturing the same, and a method for transporting articles using the soft gripper.

As one aspect, the present invention provides a chamber portion having a negative pressure action space 114 including an opening; a sucker portion having an annular contact surface extending radially outward from the opening of the chamber portion; protruding from the upper surface facing the opening of the negative pressure action space, located in the negative pressure action space, having a gas bag therein, and expandable and contractible fusion protrusions 130; It provides a pneumatic-controlled negative pressure gripper, characterized in that it includes a gas inlet and outlet which is a path through which gas flows into and out of the gas bag through the gas bag of the ridge from the outer surface of the chamber part.

The chamber has a ridge in the negative pressure action space, and the ridge is configured to be expandable and contracted by the gas injected from the outside, so that negative pressure and positive pressure inside the negative pressure action space can be formed, and the negative pressure is actively absorbed by pneumatic pressure. Adhesion and detachment are possible.

The inner wall between the sucker part and the ridge protrusion is characterized in that it has a curved shape in the inner direction of the negative pressure action space.

The ridge presses the curved forming part of the inner wall during expansion and lifts the chamber upward to increase the volume formed by the ridge, the inner wall, and the contact surface, thereby further increasing the pressure drop to negative pressure, thereby providing a strong adsorption force. to provide Conversely, when the ridges contract, the pressure of the inner wall is released and the chamber part is returned to the bottom to remove the negative pressure in the negative pressure action space so that the suction port can be detached.

In particular, the pneumatic control type negative pressure gripper of the present invention can provide a strong absorption force in water, unlike a conventional negative pressure suction port. In an underwater environment, the suction port is filled with water and it is difficult to form a negative pressure. Having an inner wall, when the ridge expands, it presses the curved forming portion of the inner wall and lifts the chamber up to form a vacuum space in the water-filled space formed by the ridge, the inner wall, and the contact surface. Strong negative pressure adsorption can be provided in water.

The ridges may be provided to form a hemispherical shape.

The negative pressure gripper may be made of a polymer material, and the polymer material may include a material selected from the group consisting of polydimethylsiloxane, polyurethane acrylate, polystyrene, polyvinyl alcohol, polyurethane, polyethylene glycol, and combinations thereof. can

The soft gripper may further include a protrusion on the surface of the sucker.

The highly soft protrusions can be densely printed on the surface of the sucker portion of the soft gripper to improve adhesion to highly rough and curved objects through better adsorption-based adhesion and sealing in water.

These structures can further establish a pressure difference on the bonding interface, as well as improve the sucker portion and the friction between the sucker portion and the surface of the object to be adhered. The hierarchical structure of the protrusions can improve the attachment of the soft gripper to rough and curved surfaces, because of their many adsorption interactions and improved capillary-assisted sealing.

As another aspect, the present invention provides a method for manufacturing a pneumatically controlled negative pressure gripper, a first polymer injection groove having a three-dimensional shape corresponding to the external shape of a chamber part and a sucker part, and a first polymer injection groove located above the middle of the first polymer injection groove 2 preparing a first mold having a polymer injection groove; A second including a cover plate portion, a columnar gas inlet portion forming portion extending from the center of the cover plate portion, and a ridge forming portion provided at the end of the columnar shape and having a shape corresponding to the inner surface of the second polymer injection groove preparing the mold; injecting a polymer material into the first polymer injection groove and the second polymer injection groove; covering the second mold on top of the first mold so that the ridge forming part is inserted into the second polymer injection groove; curing the first mold in a high-temperature environment for a certain period of time; separating the second mold; and withdrawing the soft gripper molded in the first mold from the first mold.

After preparing the second mold, the method may further include surface-treating the first mold and the second mold.

The surface treatment of the first mold and the second mold may include: immersing the first mold and the second mold in a self-assembled monolayer (SAM) solution for 50 to 70 minutes; and withdrawing the first mold and the second mold from the solution and curing the first mold and the second mold in an oven at 50 to 70° C. or higher for 11 to 13 hours.

The polymer material may include a material selected from the group consisting of polydimethylsiloxane, polyurethane acrylate, polystyrene, polyvinyl alcohol, polyurethane, polyethylene glycol, and combinations thereof.

In another aspect, the present invention provides a method for transferring an article using a pneumatically controlled negative pressure gripper, the method comprising the steps of using the soft gripper and adhering a sucker to the surface of an object to be transferred; forming a negative pressure in the negative pressure action space by supplying a fluid in the direction of the negative pressure action space of the chamber; transferring the transfer target object; and removing the negative pressure in the negative pressure action space by sucking the fluid outward of the negative pressure action space.

In one embodiment, the step of forming a negative pressure in the negative pressure action space comprises injecting a fluid into the hollow of the ridges located in the negative pressure working space to expand the ridges, and removing the negative pressure in the negative pressure working space. The step may suck the fluid from the inside of the hollow of the ridge protrusion to the outside of the gas bag.

The soft gripper according to the present invention has the advantage that it can exert and maintain sufficient adhesion to various surfaces by controlling the vacuum phenomenon in the chamber part through the expansion and contraction of the ridges, and that the attachment and detachment can be easily controlled.

In addition, there is an advantage of being able to exhibit and maintain sufficient adhesion in a dry environment as well as in an aquatic environment.

In addition, since sufficient adhesive force can be exhibited through expansion and contraction of the ridge without external pressure, there is an advantage in that it can be easily adhered to various surfaces and pressure-sensitive materials.

1 is a cross-sectional view showing the configuration of a soft gripper according to an embodiment of the present invention.
FIG. 2 is an external perspective view of the soft gripper shown in FIG. 1 .
FIG. 3 is a view illustrating a process in which the soft gripper shown in FIG. 1 is adsorbed to the surface of an object submerged in water.
4 is a flowchart illustrating a process sequence of a method for manufacturing a soft gripper according to an embodiment of the present invention.
5 is a view showing a process state of a method for manufacturing a soft gripper according to an embodiment of the present invention.
6 is a graph showing the results of measurement of adhesive force according to environmental conditions of the soft gripper according to an embodiment of the present invention.
7 is a graph showing the measurement result of the adhesive force according to the presence or absence of the ridge of the soft gripper according to an embodiment of the present invention.
8 is a graph showing the results of measuring the adhesive force according to the presence or absence of expansion of the ridges of the soft gripper according to an embodiment of the present invention.
9A is a graph showing the measurement result of adhesive force according to elasticity of the soft gripper according to an embodiment of the present invention in a dry environment.
9B is a graph showing the measurement result of the adhesive force according to the elasticity of the soft gripper according to an embodiment of the present invention in an underwater environment.
10A is a graph showing the measurement results of adhesive force according to time and pneumatic pressure of the soft gripper according to an embodiment of the present invention in a dry environment.
10B is a graph showing the measurement results of adhesive force according to time and pneumatic pressure of the soft gripper according to an embodiment of the present invention in an underwater environment.
11A is an FEM simulation image of a soft gripper according to an embodiment of the present invention during negative pressure adsorption.
11B is a graph showing predicted values and experimental values of the interfacial area and chamber height of the soft gripper according to an embodiment of the present invention with respect to the input pressure.
11C is a graph showing predicted values and experimental values of the volume of the soft gripper according to an embodiment of the present invention with respect to input pressure, and FEM simulation images.
11D is a graph showing predicted values and experimental values of the pressure difference of the soft gripper according to an embodiment of the present invention in dry and underwater conditions with respect to input pressure.
12A is a graph showing predicted values and experimental values of the adhesive strength of the soft gripper according to an embodiment of the present invention in dry and underwater conditions with respect to input pressure.
12B shows the adhesive strength of a soft gripper according to an embodiment of the present invention in dry and underwater conditions, versus time; input pressure; and a graph showing the FEM simulation image.
12C is a graph showing the adhesive strength of a soft gripper according to an embodiment of the present invention in dry and underwater conditions, versus the number of actuation/inactivation (on/off).
13A is a soft gripper according to an embodiment of the present invention having protrusions against the roughness of the surface; Soft and flat coated soft gripper according to an embodiment of the present invention; and a graph showing the adhesive strength of the soft gripper without further improvement.
13B is a graph showing adhesive strength in dry and underwater conditions versus the ratio of soft gripper to surface curvature according to an embodiment of the present invention.
14 is a diagram illustrating a state in which an object is adsorbed and transported in water using a soft gripper according to an embodiment of the present invention.
15 shows an octopus arm-derived soft actuator and three soft grippers according to an embodiment of the present invention integrated;

Hereinafter, a soft gripper, a manufacturing method thereof, and an article transport method using the soft gripper according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. Since the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the text. However, this is not intended to limit the present invention to the specific disclosed form, it should be understood to include all modifications, equivalents and substitutes included in the spirit and scope of the present invention. In describing each figure, like reference numerals have been used for like elements. In the accompanying drawings, the dimensions of the structures are enlarged than the actual size for clarity of the present invention.

Terms such as first, second, etc. may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as “comprise” or “have” are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It is to be understood that it does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

The gripping ability of the soft gripper of the present invention is governed by the expansion and contraction of the chorion 130 inside the soft gripper, which is consistent with the muscle mechanics of the biologically corresponding sucker.

The soft gripper has remarkable adhesion performance in both dry (~26 N) and underwater (~45 N) conditions caused by the pressure difference within the chamber part 110 , as well as without external physical elements. It exhibits high repeatability and responsiveness to the on/off switch of negative pressure adsorption.

1 is a cross-sectional view showing the configuration of a gripper (adsorption port) according to an embodiment of the present invention, and FIG. 2 is an external perspective view of the gripper shown in FIG. 1 .

1 and 2 , the soft gripper according to an embodiment of the present invention may include a chamber part 110 , a sucker part 120 , a ridge protrusion 130 , and a gas inlet part 140 . .

The chamber part 110 may have a negative pressure action space 114 that is opened downwardly therein. The shape of the chamber part 110 is not particularly limited, and for example, the chamber part 110 includes a planar part 111 , a side part 112 extending from the planar part 111 to form a spherical shape, and the flat surface. It may include a bottom portion 113 facing the portion 111 and positioned below the side portion 112 .

The negative pressure action space 114 may provide a space where the negative pressure acts when the soft gripper absorbs an object. The inner wall 114a of the negative pressure action space 114 may be formed by being curved in the inner direction of the negative pressure action space 114 . Accordingly, the negative pressure action space 114 may be formed in a shape that narrows from the top of the negative pressure action space 114 downward and then widens again.

The sucker part 120 is a part adsorbed to the surface of an object in the soft gripper. The sucker part 120 may extend radially from the lower part of the chamber part 110 . For example, the sucker part 120 may extend radially from the center of the bottom part 113 of the chamber part 110 . The inside of the sucker part 120 may communicate with the negative pressure action space 114 , and thus air and water may be introduced into the negative pressure action space 114 through the sucker part 120 .

The ridges 130 may protrude from the upper surface of the negative pressure action space 114 and be located in the negative pressure action space 114 , and may be configured so that negative pressure acts in the negative pressure action space 114 . To this end, the ridges 130 have elasticity that can expand and contract, expand to form a negative pressure in the negative pressure action space 114 , and contract to remove the negative pressure in the negative pressure action space 114 . As an example, the ridge 130 may have a hemispherical shape. When the hemispherical ridge 130 is expanded, it may expand to a size in close contact with the curved inner wall 114a of the negative pressure action space 114 .

The gas inlet 140 may penetrate the gas bag of the ridge protrusion 130 from the upper end of the chamber unit 110 , that is, the flat portion 111 of the chamber unit 110 . The gas inlet 140 may allow gas to be injected into the gas bag so that the ridge 130 expands, and the gas in the gas bag may be sucked so that the ridge 130 contracts.

The soft gripper according to an embodiment of the present invention may be made of any one of a silicone plastic compound and a rubber-based polymer precursor. For example, the soft gripper may include polydimethylsiloxane (PDMS), polyurethane acrylate (PUA), polystyrene (polystylene, PS), polyvinyl alcohol (PVA), polyurethane (polyurethane), polyethylene glycol. (polyethylene glycol, PEG), and a material selected from the group consisting of combinations thereof may be included.

The ridges 130 of the soft gripper expand during operation, and the expanding ridges 130 come into contact with the inner wall 114a, leading to a structural change of the chamber part 110 . Two main factors govern the adhesion of the soft gripper: (1) increased interfacial area and surface conformability and (2) volume expansion causing a decrease in the internal pressure of the soft gripper chamber part 110 .

FIG. 3 is a view for explaining a process in which the gripper of the present invention shown in FIG. 1 is adsorbed to the surface of an object in a dry environment and an underwater environment.

In the example of a dry surface, the first picture shows the gripper seated on the contact surface. The second picture is a state in which the ridge expands through the gas inlet and contacts the curved part of the inner wall. And the third picture shows the shape of the gripper going up by further expanding the chorion to further push the curved part of the inner wall outward. In the second figure, the volume is larger than the volume formed by the ridges, the inner wall, and the contact surface, and in the third figure, a more reduced negative pressure is formed to provide strong adhesion.

An example of another environment in a wet surface environment is in the diagram below in FIG. 3 . The first picture of the wet surface environment shows the gripper sitting on the contact surface in an aquatic environment. The second picture is a state in which the ridge expands through the gas inlet and contacts the curved part of the inner wall. And the third picture shows the shape of the gripper going up by further expanding the chorion to further push the curved part of the inner wall outward. In the second figure, the volume formed by the ridge, the inner wall, and the contact surface is filled with water, so it is difficult to form a negative pressure in an aquatic environment and to exert an adhesive force. However, in the third figure of the present invention, the volume becomes larger and a vacuum is formed to form a very strong negative pressure, thereby providing a very strong adhesion even in an underwater environment.

When the gripper of the present invention is to be detached from the adhesive surface, when gas is sucked outward from the gas bag of the ridge 130, the force pressing the curved inner wall as the ridge 130 contracts is lost and becomes narrow again. The raised gripper is lowered and the volume formed by the increased ridge, inner wall, and contact surface becomes smaller, and the negative pressure is lost and detachment occurs.

The specific gripping mechanism of the soft gripper

To elucidate the specific gripping mechanism of the soft gripper of the present invention, we first investigated the change in the geometry of the soft gripper during adsorption. The increase in the soft gripper interface area and chamber height as shown in FIG. 3 is measured corresponding to the change in the input pneumatic pressure; Finite element method for the phases of the non-actuated state (0 kPa), the initial contact of the swollen ridge 130 with the inner wall 114a of the chamber portion 110 (20 kPa), and the full activation of the soft gripper (80 kPa) The analysis results obtained using (FEM) simulations were compared, and are shown in FIG. 11A . Based on existing papers, what and what (Paper 37. S. Licht, E. Collins, D. Ballat-Durand, M. Lopes-Mendes, Universal jamming grippers for deep-sea manipulation, in OCEANS 2016 MTS/IEEE Monterey (IEEE) , 2016), pp. 1-5., and 38. ZE Teoh, BT Phillips, KP Becker, G. Whittredge, JC Weaver, C. Hoberman, DF Gruber, RJ Wood, Rotary-actuated folding polyhedrons for midwater investigation of delicate marine organisms. Sci. Robot. 3 , eaat5276 (2018)), the total attraction force (F _s) of a soft underwater gripper can be expressed as F _s = -PA, where P is the pressure in the chamber (110) is the pressure difference between (P _v ) and atmospheric pressure (P ₀ to 101.3 kPa), and A is the interfacial region of the adsorption effect. Based on FIG. 3 , A=πD _v2 /4, where D _v is the diameter of the interface region when a vacuum is established inside the chamber part 110 .

First, the soft gripper approaches and makes contact with a specific surface. In dry conditions, the pressure difference inside and outside the soft gripper is defined by the volume change inside its chamber part 110 as follows:

F _{s, dry} = πD _v ² /4 * P ₀ (1 - V ₀ /V _v ) (1)

Here, V ₀ is the volume of the lower chamber portion 110 when the inner wall 114a and the ridge 130 during the initial stage of negative pressure adsorption are in contact; Vv is the volume of the lower chamber part 110 in a vacuum state.

However, in water conditions, the pressure difference is induced in a different way than in dry conditions. As shown in FIG. 3, the residual air is mostly completely discharged from the inside of the chamber part 110 during the initial stage of negative pressure adsorption, which induces an extremely low pressure inside and forms an almost vacuum state even through a minimal volume change. . As P _v ~ 0 , the pressure difference between the inside and outside of the soft gripper is maximized and can be expressed as _{ΔP max} = -P _{0 .} For this reason, the adsorption force ( σ _s,UW ) of the soft gripper in water conditions is expressed as:

F _s,UW = -ΔP _max ( _{πD v} ² /4) (2)

11B reveals the predicted and experimental values of the interfacial area and chamber height during application of pneumatic pressure, measured using a miniature laser displacement measuring sensor (CD22-15VM12; Fastus, Japan) and a caliper (Vernier scale). The increase in the interfacial area and chamber height is measured to understand the expansion of the soft gripper chamber part 110 volume, which causes a decrease in its internal pressure. During operation, the interfacial area changes negligibly (<20 kPa) for low inputs of pneumatic pressure. For higher pressure input (>20 kPa), the swollen ridge 130 contacts the inner wall 114a of the soft gripper chamber portion 110; This expands the interfacial area of the sucker portion 120 and forms a curve that aids in adaptation against a round surface. Similarly, the height of the soft gripper decreases slightly during the onset of inflation, but increases steadily as the soft gripper moves away from the base. Since the behavior of the interface region and the height of the chamber part 110 for the experimental observation and the FEM simulation coincide with each other, the theoretical and experimental changes of the volume according to the varying input of the pneumatic pressure were calculated. It is assumed that the inside of the chamber part 110 is in the form of a cone with a cut end, and the volume change (V=V ₀ -V _v ) of the chamber part 110 before and after negative pressure adsorption can be expressed as follows and

ΔV = π/12 * [h ₀ (d ₀ ² +d ₀ D ₀ +D ₀ ² )-h _v (d _v ² +d _v D _v +D _v ² )] (3)

where d ₀ is the diameter of the upper portion inside the chamber portion 110 _{during the initial contact, D 0} is the diameter of the interface region of the soft gripper chamber portion 110 during the initial contact _{, and h 0 is the diameter during the initial contact} The height of the chamber part 110 . Furthermore, d _v is the diameter of the upper part inside the chamber part 110 _{in a vacuum state, D v} is the diameter of the interface region in a vacuum state, and h _v is the height of the chamber part 110 in a vacuum state. As shown in FIG. 11C , the predicted value and the experimental value of the volume of the soft gripper chamber part 110 are equal to each other; From the negative pressure adsorption of 20 kPa or more, the expansion of the soft gripper bonding the interface and the height of the chamber part 110 causes a steady increase in its internal volume. As the input pressure increases up to 80 kPa, the interfacial area and chamber height of the soft gripper chamber part 110 stop increasing, and thus the volume of the soft gripper is maximized. The predicted value of the volume change is then used to calculate the pressure difference between the inside and outside of the soft gripper. A customized device was used to measure the pressure in the chamber part 110 of the soft gripper, and the calculated result was compared with the experimental value of the measured pressure difference. As shown in FIG. 11D , the theoretical result of the pressure difference inside the soft gripper chamber part 110 with respect to the change of the input pressure is in good agreement with the experimental result.

By analyzing the pressure difference within the soft gripper chamber part 110, it is possible to measure the adhesive strength of the soft gripper corresponding to the varying input of pneumatic pressure in the dry condition (Fig. 12a). Experiments were performed using custom equipment under ambient dry conditions. The experimental value of adhesion coincides with the predicted value, which can be explained through the coincidence of the behavior of the pressure difference in the soft gripper chamber part 110 for increasing the input of pneumatic pressure. As shown in FIG. 12A , the dry adhesive strength of the soft gripper was ∼26 N for an input pressure of 80 kPa, due to the maximized pressure difference in the interfacial region of the soft gripper chamber part 110 and the sucker part 120 . is maximized Using similar experimental setups, we also compare theoretical and experimental soft gripper adhesion strengths to flat substrates immersed in water. Likewise, as shown in FIG. 12A , the soft gripper reaches a maximum adhesive strength of ˜45 N at 80 kPa input pneumatic pressure, due to the much greater pressure differential within chamber portion 110 through the formation of a vacuum. Figures 9a and 9b show the adhesive strength of the soft gripper with respect to the elastic modulus of the soft gripper according to the actuation/non-actuation transition of the input of pneumatic pressure in a dry/aquatic environment. To prepare the soft gripper, silicone elastomers having different elastic modulus, specifically Ecoflex 10 (E ~ 10 kPa), Ecoflex 30 (E ~ 30 kPa), Ecoflex 50 (E ~ 50 kPa), and Dragonskin 10 ( E ~ 300 kPa) was used. Here, the operating state is similar to the input of pneumatic pressure (20-80 kPa), while the non-actuated state is similar to the complete air release of the soft gripper. Then, in order to understand the firmness of the attachment during the operating state, and the separation during the non-operating state, the adhesive strength was measured. For both dry and water conditions, the soft gripper shows a normal increase in adhesive strength with the modulus of elasticity. This means that the adhesive strength (F _N ), E is the elastic modulus of the adhesive interface, C ~ 1/E, while the system conformance (C) (F _N ~ √(A/C), where A is the interfacial area of the soft gripper) Because it is inversely proportional to the square root of Overall, the normal adhesion of soft grippers increases with stiffness in both dry and underwater conditions; Soft grippers made of silicone with a larger E cannot be fabricated using the replication method of the present invention. Conversely, for the non-operational state, the volume of the soft gripper chamber part 110 is returned to the initial state, and the contact part of the sucker part 120 is restored by restoring the elastic force of the silicone material. This ruptures the seal between the soft gripper and the mating substrate and yields a relatively negligible soft gripper, in particular the adhesive strength of the soft gripper of greater rigidity due to the greater recovery behavior of silicone. 12B summarizes the general attachment and detachment behavior of the soft gripper. The expansion of the volume of the soft gripper chamber part 110 initiates adhesion through the adsorption effect, while the expansion of the interfacial region enables the overall adhesion to increase corresponding to the input of pneumatic pressure in the range of 20 to 80 kPa. Because of the vacuum in the chamber portion 110 , as opposed to bonding in dry conditions, the soft gripper establishes a greater pressure differential in water conditions and obtains a much greater bonding strength. When the ridge 130 is vented, the stress is broken at the contact portion, so that the soft gripper is separated. In FIG. 12b , the soft gripper firmly attaches to a weight of 1 kg in water (pneumatic pressure of ˜30 kPa), transports and most immediately detaches upon evacuation of its internal ridges 130 . Thus, the soft gripper achieves maximum normal adhesion in dry (~26 N) and underwater (~45 N) conditions and detaches most immediately upon venting. The soft gripper's ability to attach and detach is easily controlled using pneumatic pressure, making it highly suitable for gripping operations in dry and aquatic environments. After the negative pressure adsorption of the soft gripper, the body is raised during its bonding process and firmly adheres to the mating substrate. When the ridge 130 is evacuated, the seal of the soft gripper on the surface is removed, so that most of it is immediately separated. To test the durability of its gripping ability, periodic dry/water adhesion measurements of the soft gripper were tested with an actuated/non-actuated switch, as shown in FIG. 12C . Soft grippers exhibit hard, stable, and long-term adhesion of up to 10000 times during operating conditions in both dry and aquatic environments, as well as high reactivity with immediate detachment during non-operating conditions.

Additionally, we arrange highly soft, protrusions on the surface of the soft gripper sucker portion 120 to improve adhesive compliance for gripping on irregularly shaped objects. The protrusions are fabricated via a simple engraving method using a much softer derivative of a silicone elastomer (Ecoflex 10) and a polymer master with a reverse structure. The projections are densely distributed on the soft gripper sucker part 120 having high structural fidelity and integrity. For maximized adhesion properties, the hierarchical structure of the asperity is designed with a diameter of 30 μm and a spacing ratio of ˜1, as well as the geometry of the biological projections (the spacing ratio is the distance between each structure divided by the width) . We then describe a soft gripper with highly smooth protrusions in water (soft gripper-sm), defined by the root-mean-square (RMS) roughness expressed as _{R RMS} =√(1/n∑ _i=1 ⁿ *y _i ^{2 ).} Measure the adhesive strength to a substrate with varying roughness of R _RMS is however used to ensure consistency of data, while the substrate of the R _RMS ~ 100 ㎛ of the R _Max of ~ 160 ㎛, R board of the _RMS ~ 30 ㎛ has a maximum roughness (R _Max) in ~ 80 ㎛. These measurements are measured upon complete negative pressure adsorption at 80 kPa pressure input and are compared to a coated soft gripper sample with a smooth and flat surface (soft gripper-sf) and a soft gripper sample without further enhancement. On flat substrates, the soft gripper-sm reveals a slight increase in normal adhesion, due to the many interactions of the asperities. Specifically, the very small scale structure induces adsorption against the mating surfaces by the expansion of the inner wall 114a for improved adhesion interface and vacuum of the negative pressure action space 114 . Moreover, a capillary bridge is formed between the protrusion and the engaging surface, which improves the sealing of the soft gripper sucker portion 120 and contributes to the overall adhesion of the protrusion. The hierarchical structure of the protrusions, especially for surfaces with varying roughness, demonstrates the influence of the protrusions on improved surface adaptability. Irregularity prevents contact and sealing between the mating substrate and the soft gripper without further enhancement, and thus weakens the adhesive performance of the soft gripper without further enhancement. However, as shown in Fig. 13a, the soft gripper-sm shows a highly firm normal adhesion to surfaces with _{R RMS} of 30 μm and 100 μm, due to the coincident contact of the highly soft protrusions. These performances contradict that of the soft gripper- sm and that of the soft gripper without further enhancement, revealing a substantial decrease in their adhesive properties with increasing roughness ( FIG. 13A ). Thus, instead of adhering to rough surfaces in dry conditions, the soft gripper-sm has a remarkable gripping ability on surfaces with rough features, due to enhanced adsorption and interaction of the hierarchical structure of the asperities with capillary forces. reveals

In addition, the adhesive strength of the soft gripper-sm in dry and aquatic environments to substrates with varying curvatures, as defined as the soft gripper-to-surface curvature ratio (r/R), as shown in FIG. 13b , was measured. Said soft gripper-sm achieves adaptation to the geometry and obtains a firm adsorption, due to the change of the attaching interface with the increasing operation of the soft gripper. First, pneumatic pressure is applied so that the soft gripper-sm sucker part 120 and the protrusion coincide with the curved surface of the bonding object. Then, an additional input of pressure establishes a pressure differential within its chamber portion 110 interior, resulting in adsorption-based adhesion. Upon transitioning to a non-operating state in both dry and submerged conditions, the soft gripper-sm immediately separates from its mating substrate, since rupture of its seal is easily obtained by curvature.

A commercial robotic manipulator (OpenMANIPULATOR-X RM-X52-TNM, ROBOTIS) to demonstrate the gripping and transport of objects with varying geometries and shapes in water with the enhanced attachment ability of the soft gripper with its highly smooth protrusions. The practical application of the soft gripper according to an embodiment of the present invention is demonstrated by integrating the soft gripper with Using the soft gripper-sm, an easy attachment against a flat, brittle silicon wafer upon negative pressure adsorption is shown. The manipulator can easily handle the wafer in various motions and twists, and then move the wafer to a glass Petri dish, and no surface contamination or damage of the wafer was observed during separation. As the soft gripper-sm swells, the sucker portion 120 deforms to follow the curvature of the adhered object and make it possible for the projection to establish contact with the rough surface. In addition, the gripping ability of the soft gripper-sm against a relatively soft bonding object in a humid condition can easily establish adhesion to a curved surface, and the soft gripper-sm adheres to the bonding object by negative pressure adsorption and It can be separated almost immediately when the air is released after hatching.

Such a soft gripper according to an embodiment of the present invention may be manufactured through a molding mold. The forming mold may include a first mold 210 and a second mold 220 . A first mold 210 and a second mold 220 are shown in FIG. 5 .

The first mold 210 may include a first polymer injection groove 211 and a second polymer injection groove 212 . The first polymer injection groove 211 may have a three-dimensional shape corresponding to the external shapes of the chamber part 110 and the sucker part 120 of the soft gripper. The second polymer injection groove 212 may be located above the center of the first polymer injection groove 211 . The second polymer injection groove 212 may have a hemispherical shape.

The second mold 220 may include a cover plate part 221 , a gas inlet molding part 222 , and a ridge molding part 223 . The cover plate part 221 may have a rectangular plate shape having a size to cover the first mold 210 . The gas inlet forming part 222 may be formed to extend in a column shape from the bottom surface of the cover plate part 221 . The ridge forming part 223 is provided at the end of the column shape of the gas inlet forming part 222 and may have a shape corresponding to the inner surface of the second polymer injection groove 212 .

The first mold 210 and the second mold 220 may be manufactured through 3D printing or photo lithography.

The 3D-printed first mold 210 and second mold 220 may be designed using 3D computer-aided design (CAD) software (Autodesk Fusion 360, Autodesk Inc., CA, USA). have.

Parafilm was used to firmly fix the two molds to each other.

4 is a flowchart illustrating a process sequence of a method for manufacturing a soft gripper according to an embodiment of the present invention, and FIG. 5 is a diagram illustrating a process state of a method for manufacturing a soft gripper according to an embodiment of the present invention.

4 and 5 , a method for manufacturing a soft gripper according to an embodiment of the present invention includes the steps of preparing the first mold 210 ( S110 ); preparing the second mold 220 (S120); surface-treating the first mold 210 and the second mold 220 (S130); injecting a polymer material into the first polymer injection groove 211 and the second polymer injection groove 212 (S140); covering the second mold 220 on the first mold 210 so that the ridge forming part 223 is inserted into the second polymer injection groove 212 (S150); curing the first mold 210 in a high temperature environment for a predetermined time (S160); separating the second mold 220 (S170); and withdrawing the soft gripper molded in the first mold 210 from the first mold 210 ( S180 ).

Specifically, to prepare the soft, inflatable part of the soft gripper, a silicone elastomer prepolymer (Dragon Skin 10, Smooth-On Inc.) was produced by mixing with a curing agent (Dragon Skin 10: curing agent = 1:1) and , the prepolymer mixture was degassed in a vacuum chamber for 10 min. After degassing, the prepolymer mixture was deposited into a base mold to deposit the silicone precursor DragonSkin10. Then, the upper 3D-printed mold was assembled to create the ridges 130 . The prepolymer was cured at room temperature for 4 hours and demolded from the assembly.

The soft gripper was then completed by attaching the soft inflatable part to the 3D-printed substrate using a silicone adhesive (Sil-Poxy, Smooth-On Inc.).

5, (a) shows the state of the step S110 and the step S120, (b) shows the state of the step S130, and (c) shows the state of the step S140.

On the other hand, the step of surface-treating the first mold and the second mold (S130) is a self-assembled monolayer (SAM) solution diluted by 1% in hexane with the first mold and the second mold ( trichloro(octadecyl)silane (ODTS); and withdrawing the first mold and the second mold from the solution and curing the first mold and the second mold in an oven at 50 to 70° C. or higher for 11 to 13 hours.

For example, the polymer is polydimethylsiloxane (PDMS), polyurethane acrylate (PUA), polystyrene (polystylene, PS), polyvinyl alcohol (PVA), polyurethane (polyurethane), polyethylene glycol (polyethylene glycol, PEG), and combinations thereof.

The engraving of the protrusion may be performed on the surface of the sucker part 120 of the soft gripper manufactured as described above.

A SAM-treated PDMS master was first attached to the glass substrate. A highly soft silicone elastomer prepolymer (Ecoflex 10, Smooth-On Inc.) was deposited on a PDMS master followed by spin-coating at 200 rpm for 1 minute. The soft gripper was then carefully transferred onto the spin-coated PDMS master so that the sucker portion 120 was only in contact with a very small pattern. After curing at room temperature for 4 hours, the soft gripper was removed from the PDMS master and the protrusion was implanted on the soft gripper sucker 120 .

[Example 1]

After preparing the first mold 210 and the second mold 220, the first mold 210 and the second mold 220 are immersed in a self-assembled monolayer (SAM) solution for 60 minutes. The surface is treated by curing in an oven at 60° C. for 12 hours, and polyurethane acrylic liquid as a UV-curable polymer material is formed in the first polymer injection groove 211 and the second polymer injection groove 212 of the first mold 210 . Rate (PUA) (or UV-curable polymer material is PDMS) is injected, and the second mold 220 is inserted into the second polymer injection groove 212 so that the ridge forming part 223 is inserted into the first mold 210 upper part. After covering with UV light, curing was performed for 2 hours. Then, after the second mold 220 was separated from the first mold 210 , the soft gripper formed by curing the polymer material was withdrawn from the first mold 210 .

How to measure the geometry of the soft gripper

In order to measure the change in height of the soft gripper chamber part 110, a small laser displacement sensor (CD22-15VM12, Fastus, Japan) attached to the raised platform was utilized. A 3D printed model was used to position the laser into the soft gripper in the middle of the chorion 130 . Pneumatic pressure was applied to the ridge 130 chamber from 0 kPa to 80 kPa in increments of 10 kPa, using an electrical pressure calibrator (719Pro, Fluke Inc.), and the change in displacement was measured. _{Measurements of the inner (D i} ) and outer (D _o ) diameters of the soft gripper sucker part 120 , as well as the diameter of the swollen ridges 130 ( d ) were performed using a caliper (Vernier scale).

Soft gripper chamber part 110 pressure measurement

The soft gripper sample was placed into a 3D-printed stand, allowing both measurement of the operation of the soft gripper from the top and measurement of the pressure within the soft gripper chamber portion 110 from the bottom. The bottom was connected to a pressure sensor (40PC001B1A Honeywell Inc.) with dosing tube, applying pneumatic pressure using an electric pressure calibrator. Pneumatic pressure was applied to the ridge 130 in the chamber 110 from 0 kPa to 80 kPa in a unit increment of 10 kPa, and the change in pressure in the chamber 110 was observed using an oscilloscope through the difference in voltage output. did.

Determination of adhesion of soft grippers

^{Flat, rough, and curved s-PUA substrates (area ~5 × 5 cm 2} ) in dry (~50% relative humidity) and underwater conditions under ambient conditions using custom equipment (Adhesion tester, Neo-Plus, Korea) All normal adhesion tests were performed for To run the measurements in water conditions, the s-PUA substrates were immersed in distilled water. Then, the soft gripper sample was fixed on a jig and connected to an electric pressure calibrator through a tube. An electric pressure calibrator was utilized to ensure the operation of the soft gripper according to a specific value of the input pressure. The soft gripper first made contact with the substrate with a negligible preload. When a certain pneumatic pressure was inserted into the ridge 130, the soft gripper experienced adhesion until the sample was completely separated from the substrate. The lowest peak of the normal adhesion profile determined the adhesion strength of the soft gripper. Adhesion performance against PUA substrates was mostly similar to that against glass or silicon substrates. All measurements were repeated at least 10 times, and the average value was indicated.

Adhesion measurement according to environmental conditions

6 is a graph showing the results of measurement of adhesive force according to environmental conditions of the soft gripper according to an embodiment of the present invention.

Adhesion was measured by attaching the soft gripper of Example 1 on a silicon substrate, and the adhesive force of Example 1 was measured in each of the dry state and the water state. As a result, as shown in FIG. 6 , it was confirmed that the adhesion in the water state was about twice or more higher than that in the dry state.

[Comparative example]

As a comparative example of the soft gripper according to Example 1, a soft gripper in which the ridges 130 were omitted was manufactured.

Adhesive force measurement according to the presence or absence of ridges

7 is a graph showing the results of measuring the adhesive force according to the presence or absence of the ridges 130 of the soft gripper according to an embodiment of the present invention.

The soft gripper according to Example 1 and the soft gripper according to Comparative Example were attached on a silicon substrate in water, and the respective adhesive strengths were measured. As a result, as shown in FIG. 7 , it was confirmed that the adhesive strength of Example 1 (a) was significantly higher than that of Comparative Example (b).

Adhesive force measurement according to the presence or absence of ridge expansion

8 is a graph showing the results of measuring the adhesive force according to the presence or absence of expansion of the ridges 130 of the soft gripper according to an embodiment of the present invention.

Attaching the soft gripper according to Example 1 on a silicon substrate in water, when pneumatic pressure is injected into the ridge 130 to expand and adhere (a), and only by vertical pressure without injection of pneumatic pressure Adhesive strength according to each case (b) was measured. As a result, as shown in FIG. 8 , it was confirmed that the adhesive force was higher in the case of (a).

Adhesive force measurement according to elasticity of soft gripper

9A is a graph showing the measurement result of adhesion according to the elasticity of the soft gripper according to an embodiment of the present invention in a dry environment, and FIG. It is a graph showing the adhesive force measurement result.

A soft gripper was manufactured according to Example 1, but the adhesive force was measured for each of the four soft grippers having different elastic modulus. The four soft grippers each had an elastic modulus of 10 kPa, 30 kPa, 50 kPa, and 70 kPa, and for each of these soft grippers, the adhesive force was measured by attaching it on a silicon substrate, and the adhesive force was measured in a dry environment and an underwater environment, respectively. As a result, as shown in FIGS. 9A and 9B , it was confirmed that the higher the elastic modulus, the greater the adhesive force.

Determination of adhesion over time and pneumatics

10A is a graph showing the measurement results of adhesive force according to time and pneumatic pressure of the soft gripper according to an embodiment of the present invention in a dry environment, and FIG. 10B is a time of the soft gripper according to an embodiment of the present invention in an underwater environment. And it is a graph showing the measurement result of the adhesive force according to the pneumatic pressure.

After attaching the soft gripper according to Example 1 on the silicon substrate, the adhesive force was measured while gradually increasing the time and air pressure, and the adhesive force was measured in a dry environment and an underwater environment, respectively. As a result, as shown in FIGS. 10A and 10B , it was confirmed that the adhesive force increased as time and air pressure increased.

14 is a diagram illustrating a state in which an object is adsorbed and transported in water using a soft gripper according to an embodiment of the present invention. The object shown in FIG. 14 is an object having a weight of 500 g.

14, if the soft gripper is adsorbed on the surface of the object by injecting air pressure in the water and then the object is transferred out of the water, the object is easily moved out of the water by the soft gripper. could be removed from the object.

Soft gripper for versatile gripping of complex objects and biological samples

Furthermore, in the present invention, an integrated soft gripper is assembled by integrating an octopus arm-derived soft actuator and three soft gripper-sms, which can be deformed in response to negative pressure adsorption. The integrated soft gripper is shown in FIG. 15 . This is more effective for hard, shape-fitting phages on complex polyhedra, rough objects, and delicate and/or wet biological samples (eg, porcine heart, and liver).

In addition, we design signal and pressure circuits to simultaneously regulate the operation of the soft gripper arm and soft gripper-sms. The integrated soft gripper and circuit are then connected to a commercial manipulator and controlled using a button module for further gripping verification of complex objects. We initially measure the curvature profile for pneumatic expansion and air evacuation of the soft gripper. Here, deformation is highly responsive to increases and decreases in input pressure, and specifies the ability to conform to objects of varying complexity. As shown in FIG. 15 , the soft gripper arm flexes in response to input pressure and the soft gripper-sms actuates through a separate path of pneumatic pressure. Thus, the soft gripper achieves adaptability and highly consistent gripping performance for "wet" piggy banks, as well as pig liver and heart biological samples in aquatic environments. The integrated soft gripper is effective for negative pressure adsorption and transport of wet piggy banks, pig hearts, and pig livers. This highlights the potential of the soft gripper of the present invention not only for the excellent gripping ability of the integrated soft gripper itself, but also for the medical use of the integrated soft gripper during surgery.

The description of the presented embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the scope of the invention. Thus, the present invention is not intended to be limited to the embodiments presented herein, but is to be construed in the widest scope consistent with the principles and novel features presented herein.

Claims (13)

a chamber part having a negative pressure action space including an opening;
a sucker portion having an annular contact surface extending radially outward from the opening of the chamber portion;
a fusion protrusion protruding from the upper surface facing the opening of the negative pressure action space and positioned in the negative pressure action space, having a gas bag therein, and capable of expanding and contracting;
It is characterized in that it includes a gas inlet and outlet which is a path through which gas flows into and out of the gas bag through the gas bag of the ridge from the outer surface of the chamber part,
Pneumatically controlled negative pressure gripper. According to claim 1,
The inner wall between the sucker part and the ridge protrusion is characterized in that it has a curved shape in the inner direction of the negative pressure action space,
Pneumatically controlled negative pressure gripper. 3. The method of claim 2,
The chamber part, characterized in that the jar shape,
Pneumatically controlled negative pressure gripper. According to claim 1,
The ridges are characterized in that they have a hemispherical shape,
Pneumatically controlled negative pressure gripper. According to claim 1,
Characterized in that it further comprises a protrusion on the surface of the sucker part (120),
Pneumatically controlled negative pressure gripper. 3. The method of claim 2,
wherein the pneumatically controlled negative pressure gripper can be used underwater,
Pneumatically controlled negative pressure gripper. According to claim 1,
wherein the pneumatically controlled negative pressure gripper is made of a material selected from the group consisting of polydimethylsiloxane, polyurethane acrylate, polystyrene, polyvinyl alcohol, polyurethane, polyethylene glycol, and combinations thereof,
Pneumatically controlled negative pressure gripper. A method for manufacturing the pneumatically controlled negative pressure gripper of claim 1, comprising:
preparing a first mold having a first polymer injection groove having a three-dimensional shape corresponding to the external shape of the chamber and the sucker and a second polymer injection groove positioned above the middle of the first polymer injection groove;
A second including a cover plate portion, a columnar gas inlet portion forming portion extending from the center of the cover plate portion, and a ridge forming portion provided at the end of the columnar shape and having a shape corresponding to the inner surface of the second polymer injection groove preparing the mold;
injecting a polymer material into the first polymer injection groove and the second polymer injection groove;
covering the second mold on top of the first mold so that the ridge forming part is inserted into the second polymer injection groove;
curing the first mold in a high-temperature environment for a certain period of time;
separating the second mold; and
drawing the gripper molded in the first mold from the first mold,
A method for manufacturing a pneumatically controlled negative pressure gripper. 9. The method of claim 8,
After preparing the second mold,
The method further comprising the step of surface-treating the first mold and the second mold,
A method for manufacturing a pneumatically controlled negative pressure gripper. 10. The method of claim 9,
The step of surface-treating the first mold and the second mold,
immersing the first mold and the second mold in a self-assembled monolayer (SAM) solution for 50 to 70 minutes; and
Drawing out the first mold and the second mold from the solution, characterized in that it comprises the step of curing in an oven of 50 to 70 ℃ or more for 11 to 13 hours,
A method for manufacturing a pneumatically controlled negative pressure gripper. 9. The method of claim 8,
The polymer material is characterized in that it comprises a material selected from the group consisting of polydimethylsiloxane, polyurethane acrylate, polystyrene, polyvinyl alcohol, polyurethane, polyethylene glycol, and combinations thereof,
A method for manufacturing a pneumatically controlled negative pressure gripper. The pneumatically controlled negative pressure gripper of claim 1 is used,
Adhering the sucker to the surface of the object to be transferred;
forming a negative pressure in the negative pressure action space by supplying a gas toward the negative pressure action space of the chamber;
transferring the transfer target object; and
It characterized in that it comprises the step of removing the negative pressure in the negative pressure action space by sucking the fluid outward of the negative pressure action space,
A method of transporting goods using a pneumatically controlled negative pressure gripper. 13. The method of claim 12,
In the step of forming a negative pressure in the negative pressure action space, the fluid is injected into the gas bag of the ridges located in the negative pressure operation space to expand the ridges,
The step of removing the negative pressure in the negative pressure action space is characterized in that the fluid is sucked from the inside of the gas bag of the ridge protrusion toward the outside of the gas bag,
A method of transporting goods using a pneumatically controlled negative pressure gripper.

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