Frog tongue-like soft actuator

Abstract

The application discloses a frog tongue-imitating soft actuator and belongs to the field of soft robots, comprising a paper folding module, a connecting piece one and a movable block; two ends of the connecting piece one are fixedly connected with one movable block; the connecting piece one and the movable block are internally provided with a cavity one in communication; an electrostatic adsorption unit, comprising a positive electrode and a negative electrode; wherein the connecting piece one is fixedly installed with the electrostatic adsorption unit on one side close to each other; two electrostatic adsorption units are fixedly connected; compared with the prior art, the application utilizes the excellent unfolding / contraction ratio of double paper folding, the actuator body can realize larger unfolding movement under the premise of compact and light small volume, which is helpful for imitating the contraction and expansion activities of the chameleon tongue during the hunting process, and the front end of the actuator has the ability to operate / grasp fragile, light and planar objects through slight contact through the electrostatic adsorption structure.

Description

Technical Field

[0001] This invention relates to the field of soft robots, and more specifically to a frog-tongue-inspired soft actuator. Background Technology

[0002] Origami involves repeatedly bending thin paper without stretching or tearing it, transforming a flat sheet into a two- or three-dimensional geometric shape. A single fold can create a fixed, stable hinge structure, allowing it to be folded into a compact shape when not in use and to move freely when deployed. Electrostatic adsorption technology, on the other hand, embeds separating electrodes within an insulating medium and applies a kilovolt-level high voltage. It utilizes the adsorption force generated by polarization on the dielectric surface to adsorb a target material, offering irreplaceable advantages in grasping flat objects and handling extremely fragile objects such as cigarette ash.

[0003] Woongbae Kim et al. (Woongbae Kim, Jaemin Eom, and Kyu-Jin Cho. A Dual-Origami Design that Enables the Quasi-Quaternary Deployment and Bending Motion of Soft Robots and Grippers. Adv. Intell. Syst. 2022, 4, 2100176.) based on the double origami actuator, by adding a folded strain-limiting layer structure on the inner side of the actuator's bending, the motion behavior of the actuator is restricted to bending motion, which greatly improves the gripping ability of the double origami actuator. However, (1) the limiting layer is designed to be printed together with the actuator, which sacrifices the original extension ability of the double origami actuator; (2) the output force at the end of the actuator is low and cannot operate fragile and flat objects; (3) when the limiting layer is unfolded, it presents two large-angle intersecting curved surfaces with a certain curvature, while the fluid-driven actuator itself presents an expanded spherical curved surface after input pressure, which cannot provide a flat surface for the installation of electrostatic adsorption pads. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a frog-tongue-like soft actuator. Based on a bio-inspired dual-mode deformation double origami structure, it utilizes fluid-driven stimulation to induce quasi-sequential stretching and bending behaviors caused by the asymmetric unfolding of inextensible origami components. By rationally setting the components, the motion behavior of the origami structure is designed. Electrostatic adsorption is introduced to enhance the planar manipulation and fragile item handling capabilities lacking in the original double origami structure. The components are manufactured using low-cost fused deposition modeling 3D printing and silicone molding, ultimately realizing a biomimetic soft actuator with a chameleon tongue-like working mode and function on the double origami structure.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A frog-tongue-inspired soft actuator, comprising:

[0007] The origami module includes a connector and a movable block; each end of the connector is fixedly connected to a movable block; the connector and the movable block have a communicating cavity inside them.

[0008] An electrostatic adsorption unit, which includes a positive electrode and a negative electrode;

[0009] The electrostatic adsorption units are fixedly installed on one side of each connector that is close to each other; the two electrostatic adsorption units are fixedly connected.

[0010] In some embodiments, at least one origami module is provided; adjacent origami modules are connected by a second connector; the second connector is provided with a cavity communicating with the first cavity; the second connector is located on the side of the origami module away from the first connector.

[0011] In some embodiments, the electrostatic adsorption unit is fixedly installed on the side of one of the origami modules away from the other origami modules; the electrostatic adsorption unit is fixedly installed on the side of the two connectors of the remaining origami modules that are close to each other, and the two electrostatic adsorption units are fixedly connected.

[0012] In some embodiments, the origami module, which is equipped with two of the electrostatic adsorption units, is fixedly mounted with a flexible film; the flexible film is provided with creases; and the electrostatic adsorption units are fixedly mounted on both sides of the creases of the flexible film.

[0013] In some embodiments, the positive electrode includes a first positive electrode strip and a second positive electrode strip; the second positive electrode strips are linearly and evenly distributed on the first positive electrode strip; the negative electrode includes a first negative electrode strip and a second negative electrode strip; the first negative electrode strip is linearly and evenly distributed on the second negative electrode strip; a second negative electrode strip is disposed between two adjacent second positive electrode strips; a second positive electrode strip is disposed between two adjacent second negative electrode strips.

[0014] In some embodiments, the gap between the second positive electrode strip and the second negative electrode strip is between 0.5 mm and 1 mm.

[0015] In some embodiments, the electrostatic adsorption unit further includes a silicone layer; the positive and negative electrodes are disposed within the silicone layer.

[0016] In some embodiments, the origami module and connector 2 are formed by fused deposition modeling 3D printing.

[0017] In some embodiments, the system further includes a micro pump, a pneumatic pressure regulating valve, a high-voltage DC regulated switching power supply, and an adjustable DC regulated power supply; wherein the micro pump and the pneumatic pressure regulating valve are connected to the origami module via a hose to form an air circuit; the high-voltage DC regulated switching power supply is connected to the positive and negative terminals of the electrostatic adsorption unit via aluminum foil wires; the adjustable DC regulated power supply is connected to the pneumatic pressure regulating valve; and the adjustable DC regulated power supply is connected to the micro pump.

[0018] In some embodiments, the flexible membrane is a PI membrane.

[0019] The beneficial effects of this invention are:

[0020] Utilizing the excellent unfolding / contraction ratio of double origami, the actuator body achieves significant unfolding motion within a compact and lightweight volume, facilitating the mimicry of the contraction and extension movements of a chameleon's tongue during predation. The double origami structure of the actuator body is driven by expansion upon fluid input into a fluid network chamber embedded within the folded body. This primarily extensional motion characteristic within a certain range is highly beneficial for mimicking the working mechanism of a chameleon's tongue. Subsequently, the actuator's motion is mainly bending. The motion characteristics of the double origami actuator can be guided by designing the size and structure of the limiting layer to achieve the ideal unfolding mode and working range.

[0021] By introducing an electrostatic adsorption structure, the actuator's front end gains the ability to manipulate / grasp fragile, lightweight, and planar objects with only slight contact, similar to a chameleon's tongue capturing an insect—a capability that is difficult to achieve effectively with actuators based on other principles. Furthermore, a precisely designed, non-stretchable electrostatic adsorption layer replaces the original constraint layer structure. By designing the new dimensions of the electrostatic adsorption constraint layer, the actuator can achieve better bending characteristics, expanding its application in soft robot grippers and helping this type of double-folding paper gripper to obtain greater grasping force during object manipulation.

[0022] The components are manufactured using simple fused deposition modeling 3D printing technology and silicone molding process. With the advantage of low cost, it does not involve complex manufacturing processes. The pneumatic and electrical connections for controlling the actuator are simplified by using effective components, but room for improvement in future expansion of functions and application scope is reserved. Attached Figure Description

[0023] The invention will now be further described with reference to the accompanying drawings.

[0024] Figure 1 This is a schematic diagram of the actuator composed of the electrostatic adsorption unit and the double folding structure of this application.

[0025] Figure 2This application describes the actuator top electrostatic adsorption unit structure and the confinement layer structure with electrostatic adsorption function;

[0026] Figure 3 This is a structural schematic diagram of the double origami module of this application;

[0027] Figure 4 This is a schematic diagram of the actuator of this application deforming under positive pressure. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] In the description of this invention, it should be understood that the terms "opening", "upper", "lower", "thickness", "top", "middle", "length", "inner", "around", etc., which indicate orientation or positional relationship, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the components or elements referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting this invention.

[0030] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0031] A frog-tongue-inspired soft actuator, comprising:

[0032] The origami module includes a connector and a movable block; each end of the connector is fixedly connected to a movable block; the connector and the movable block have a communicating cavity inside them.

[0033] An electrostatic adsorption unit, which includes a positive electrode and a negative electrode;

[0034] The electrostatic adsorption units are fixedly installed on one side of each connector that is close to each other; the two electrostatic adsorption units are fixedly connected.

[0035] In some embodiments, at least one origami module is provided; adjacent origami modules are connected by a second connector; the second connector is provided with a cavity communicating with the first cavity; the second connector is located on the side of the origami module away from the first connector.

[0036] In some embodiments, the electrostatic adsorption unit is fixedly installed on the side of one of the origami modules away from the other origami modules; the electrostatic adsorption unit is fixedly installed on the side of the two connectors of the remaining origami modules that are close to each other, and the two electrostatic adsorption units are fixedly connected.

[0037] In some embodiments, the origami module, which is equipped with two of the electrostatic adsorption units, is fixedly mounted with a flexible film; the flexible film is provided with creases; and the electrostatic adsorption units are fixedly mounted on both sides of the creases of the flexible film.

[0038] In some embodiments, the positive electrode includes a first positive electrode strip and a second positive electrode strip; the second positive electrode strips are linearly and evenly distributed on the first positive electrode strip; the negative electrode includes a first negative electrode strip and a second negative electrode strip; the first negative electrode strip is linearly and evenly distributed on the second negative electrode strip; a second negative electrode strip is disposed between two adjacent second positive electrode strips; a second positive electrode strip is disposed between two adjacent second negative electrode strips.

[0039] In some embodiments, the gap between the second positive electrode strip and the second negative electrode strip is between 0.5 mm and 1 mm.

[0040] In some embodiments, the electrostatic adsorption unit further includes a silicone layer; the positive and negative electrodes are disposed within the silicone layer.

[0041] The frog-tongue-inspired soft actuator provided by the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0042] See Figure 1 The three origami modules 1, connector 2 3, and base 26 of electrostatic adsorption unit 2 were integrated and printed using flexible TPU material by a 3D printer. The electrostatic adsorption unit 2 and flexible membrane 4 were made separately and then spliced ​​together.

[0043] The origami module 1 includes a connector 11 and a movable block 12; each end of the connector 11 is fixedly connected to a movable block 12; the connector 11 and the movable block 12 are provided with a communicating cavity 13; adjacent origami modules 1 are connected by a connector 2 3; the connector 2 3 is provided with a cavity 2 communicating with the cavity 13; the connector 2 3 is located on the side of the origami module 1 away from the connector 11.

[0044] like Figure 1As shown, the base 26 is mounted on the movable block 12 of one origami module 1, and the remaining origami modules 1 are fixedly mounted with flexible film 4 between two movable blocks 12; electrostatic adsorption unit 2 is mounted on the base 26, and electrostatic adsorption unit 2 is mounted on both sides of the crease 43 of the flexible film 4.

[0045] See origami structure instructions. Figure 3 During the deformation of the origami structure caused by the input positive pressure, due to the thickness difference between connector 11 and connector 3 (connector 3 being thinner), the movable blocks on both sides inflate and expand, forming contact with the outer walls and interacting earlier. This results in the actuator based on the origami structure generally biasing towards connector 3, producing limited bending. Therefore, the base 26 of the electrostatic adsorption unit 2 and the flexible membrane 4, which acts as a limiting layer, are designed on this side.

[0046] See Figure 2 The flexible membrane 4 uses a 0.050 mm thick PI film that is non-stretchable and has a non-adhesive surface. A 3D-printed mold is coated with a conductive ink that can solidify. After the mold is removed, the conductive ink solidifies on the PI film, forming an interdigitated shape to complete the electrode fabrication of electrostatic adsorption unit 2. Since the effective electrode area and the electrode edge length are important factors positively correlated with the electrostatic adsorption force, the interdigitated shape of the electrode can achieve a more ideal adsorption force under the premise of limited overall size of the electrostatic adsorption pad. The electrode plate width is designed to be about 1mm and the electrode plate gap is designed to be 0.5mm-1mm to avoid the electrode breaking down the sealing insulation layer and forming a circuit path to generate discharge due to the gap being too small, or the gap being too large to weaken the adsorption effect. After the electrode is cured, the adhesive aluminum foil wire 44 is connected to the electrode, and a liquid silicone layer 25 is covered and left to cure. After the product is cut, the electrostatic adsorption unit 2 is completed. Then, the electrostatic adsorption unit 2 is glued to the base 26 at the top of the origami module 1 with special silicone glue to complete the fabrication of the electrostatic adsorption unit 2 at the tongue tip. One side of the PI film serves as the adsorption surface dielectric layer of the electrostatic adsorption pad and is in direct contact with the target material when adsorbing the target material.

[0047] Cut the PI film and fold it three times to obtain three creases (43). See [reference needed]. Figure 2 The central V-shaped crease 43 and the two end bonding areas 41 are obtained. The two flat areas 42 in the middle are used to add electrostatic adsorption units 2. The manufacturing process is the same as that of the electrode pattern and the electrostatic adsorption unit 2 at the tip of the tongue. After the manufacturing is completed, glue is used to attach it to the corresponding part of the origami module 1.

[0048] The pneumatic and electrical connection module for the actuator includes a miniature pump (Kamoer, KVP8-KK-S type) that provides pneumatic input. It is connected to an SMC type pneumatic precision pressure regulating valve (Anker Automation, IR1020-01-A type, equipped with digital display) via a PU hose with an inner diameter of 2.5mm and an outer diameter of 4mm. The pressure regulating valve is connected to the actuator via a PU hose to complete the pneumatic connection. The electrical components include a Dongwen high-voltage DC regulated switching power supply connected to the two electrodes of the electrostatic adsorption unit, and an adjustable DC regulated power supply (Ulead, UTP1306S) that supplies power to the miniature pump and the digital display on the pressure regulating valve, respectively.

[0049] Connect the electrodes of electrostatic adsorption unit 2 to a high-voltage power supply. Connect the two wires leading from the electrodes of each electrostatic adsorption unit 2 to the positive and negative terminals of the high-voltage power supply, respectively. After connecting the micro pump, pressure regulating valve, and actuator, adjust the pressure regulating valve to adjust the air pressure output to the actuator. When positive pressure is applied, the internal cavity of the actuator is inflated, causing the cavity wall to expand and deform, similar to a balloon inflating. The actuator changes from a contracted state to an extended state. The extended state of the actuator is as follows: Figure 4 As shown. The restrictive layer formed by the flexible membrane 4 has a restraining effect on the actuator's unfolded state. If the restrictive layer is too short, it will prematurely pull the actuator into bending and deformation; if the restrictive layer is too long, it will not be able to fully unfold after the actuator reaches the target unfolded state. Therefore, the length of the restrictive layer is reasonably designed according to the magnitude of the input positive pressure to achieve the ideal unfolded state of the actuator. The electrodes are connected to a high-voltage power supply through wires and generate electrostatic adsorption force after being energized. It can capture objects with extremely small mass and volume or fragile objects such as cigarette ash and scraps of paper, just like a chameleon's tongue. It can also perform suction operations on planar objects. The existence of adsorption area 1 51, adsorption area 2 52, and adsorption area 3 53 formed by the electrostatic adsorption unit 2 enables the actuator to have adsorption capabilities in multiple parts and is conducive to further expansion as a gripper in the future.

[0050] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A frog-tongue-inspired soft actuator, characterized in that, include: The origami module (1) includes a connector (11) and a movable block (12); each end of the connector (11) is fixedly connected to a movable block (12); the connector (11) and the movable block (12) are provided with a communicating cavity (13); At least two origami modules (1) are provided; adjacent origami modules (1) are connected by connector two (3); connector two (3) is provided with a cavity two communicating with cavity one (13); connector two (3) is provided on the side of origami module (1) away from connector one (11); An electrostatic adsorption unit (2) includes a positive electrode and a negative electrode; The base (26) is mounted on the movable block (12) of one origami module (1), and the remaining origami modules (1) are fixedly mounted with flexible films (4) between the two movable blocks (12); electrostatic adsorption units (2) are mounted on the base (26), and electrostatic adsorption units (2) are mounted on both sides of the crease (43) of the flexible film (4); The flexible membrane (4) is a PI membrane. The PI membrane is cut and folded three times to obtain three creases (43), resulting in a central V-shaped crease (43) and two end bonding areas (41). The two flat areas in the middle (42) are used to add electrostatic adsorption units (2). During the process of deformation of the origami module (1) caused by the input positive pressure, due to the thickness difference between connector 1 (11) and connector 2 (3), connector 2 (3) is thinner, and the movable blocks (12) on both sides inflate and expand to form contact with the outer wall and generate interaction earlier, the actuator as a whole tends to bend to the side of connector 2 (3). Based on this, the base (26) of the electrostatic adsorption unit (2) and the flexible membrane (4) that acts as the limiting layer are designed on this side.

2. The frog-tongue-like soft actuator according to claim 1, characterized in that, The positive electrode includes a positive electrode strip one (21) and a positive electrode strip two (22); the positive electrode strip one (21) is linearly and evenly distributed with positive electrode strip two (22); the negative electrode includes a negative electrode strip one (23) and a negative electrode strip two (24); the negative electrode strip one (23) is linearly and evenly distributed with negative electrode strip two (24); a negative electrode strip two (24) is disposed between two adjacent positive electrode strip two (22); a positive electrode strip two (22) is disposed between two adjacent negative electrode strip two (24).

3. The frog-tongue-like soft actuator according to claim 2, characterized in that, The gap between the second positive electrode strip (22) and the second negative electrode strip (24) is between 0.5 mm and 1 mm.

4. The frog-tongue-like soft actuator according to claim 1, characterized in that, The electrostatic adsorption unit (2) further includes a silicone layer; the positive electrode and the negative electrode are disposed within the silicone layer.

5. The frog-tongue-inspired soft actuator according to claim 1, characterized in that, The origami module (1) and connector 2 (3) are formed by fused deposition modeling 3D printing.

6. The frog-tongue-inspired soft actuator according to claim 1, characterized in that, It also includes a micro pump, a pneumatic pressure regulating valve, a high-voltage DC regulated switching power supply and an adjustable DC regulated power supply; wherein the micro pump and the pneumatic pressure regulating valve are connected to the origami module (1) through a hose to form an air circuit; the high-voltage DC regulated switching power supply is connected to the positive and negative terminals of the electrostatic adsorption unit (2) through aluminum foil wires respectively; the adjustable DC regulated power supply is connected to the pneumatic pressure regulating valve; the adjustable DC regulated power supply is connected to the micro pump.

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