CN116619346B

CN116619346B - A negative pressure pneumatic artificial muscle actuator with built-in prestrain

Info

Publication number: CN116619346B
Application number: CN202310591544.9A
Authority: CN
Inventors: 王韬; 付国强; 王熙; 鲁彩江
Original assignee: Southwest Jiaotong University
Current assignee: Southwest Jiaotong University
Priority date: 2023-05-24
Filing date: 2023-05-24
Publication date: 2025-08-05
Anticipated expiration: 2043-05-24
Also published as: CN116619346A

Abstract

The present invention discloses a negative pressure pneumatic artificial muscle actuator with built-in prestrain, comprising an elongated and deformable flexible cavity and a wire cage-type support structure disposed within the prestretched flexible cavity. The support structure comprises at least three support plates with identical contours arranged in parallel from top to bottom, with adjacent support plates vertically connected by a plurality of inextensible flexible wires. The flexible wires are evenly distributed along the edges of the support plates to form a flexible wire group, forming a wire cage-type support structure. An air hole is provided in the center of the top support plate for negative pressure drive, and holes are provided in the middle of all intermediate support plates except the top and bottom support plates. The flexible cavity is cylindrical, and after the flexible cavity is prestretched circumferentially to an inner diameter equal to the outer diameter of the support structure, the support structure is placed within the flexible cavity, and the flexible cavity is then sealed to obtain the artificial muscle actuator. The present invention solves the problems of uncertainty and poor controllability in the output characteristics of negative pressure pneumatic artificial muscle actuators.

Description

Negative pressure pneumatic artificial muscle driver with built-in pre-strain

Technical Field

The invention relates to the technical field of artificial muscle driving, in particular to a negative pressure pneumatic artificial muscle driver with built-in pre-strain.

Background

The artificial muscle is a driver which can simulate the deformation characteristic of biological muscle and has flexibility, and has important application value in the fields of flexible/soft robots, wearable equipment, medical equipment, rehabilitation equipment and the like. At present, the negative pressure pneumatic artificial muscle has great development potential due to the advantages of high power density, large output strain, good safety, compact structure, environmental friendliness and the like. Currently, negative pressure pneumatic artificial muscle drivers are mainly composed of two parts, namely a supporting structure (such as a spring, a paper folding structure, a rubber beam and the like) and a non-extensible flexible cavity (such as a plastic bag, a plastic cavity, a fabric bag and the like). Under the action of negative air pressure, the soft cavity is contracted inwards, and a proper supporting structure is designed in the soft cavity, so that the deformation mode of the soft cavity can be guided, and the driving function of the contraction deformation simulation muscle is realized. Different negative pressure pneumatic drives can be obtained by different support structures and flexible cavity designs. However, under the action of negative air pressure, the flexible cavity is contracted inwards, meanwhile, the artificial muscle is contracted along the axial direction, in the process, the inextensible flexible cavity is wrinkled and buckled, the randomness of the wrinkled and buckled deformation causes certain uncertainty of deformation and output force of the artificial muscle driver, and the artificial muscle driver cannot be applied to practical scenes with high accuracy requirements.

In order to weaken uncertainty of skin fold deformation in the contraction process of the artificial muscle driver, one method is to carry out paper folding structural design on the skin, and carry out paper folding design on corners of the skin, so that the skin is orderly deformed according to folds in the contraction process of the artificial muscle, thereby weakening uncertainty of fold deformation, and obtaining the negative pressure pneumatic artificial muscle driver with high deformation accuracy and good controllability. The artificial muscle can simulate the contraction deformation of the muscle, but because the flexible cavity is dependent on the inextensible flexible cavity material, the flexible cavity randomly generates folds and buckling deformation in the contraction deformation process, the accuracy and the controllability of the deformation of the driver are reduced, and the practical application is limited. In addition, in the deformation process of the artificial muscle driver under the action of negative pressure, the generation of wrinkles weakens the integral flexibility of the driver to a certain extent. In addition, through the paper folding design, the flexible cavity can be enabled to realize orderly deformation along with the shrinkage deformation of the artificial muscle driver, but the method cannot be suitable for a driver with a circular section, and meanwhile, the design complexity is brought.

Disclosure of Invention

In order to solve the problems of uncertainty and poor controllability of output characteristics of the negative pressure pneumatic artificial muscle driver, the invention provides a negative pressure pneumatic artificial muscle driver with built-in pre-strain.

The invention provides a built-in pre-strained negative pressure pneumatic artificial muscle driver, which comprises an extendably deformable flexible cavity and a wire cage type supporting structure arranged in the pre-stretched flexible cavity.

The supporting structure comprises at least three supporting plates which are arranged in parallel from top to bottom and have the same outline, and two adjacent supporting plates are vertically connected through a plurality of inextensible flexible lines. All flexible wires are equal in length and equal in distance between two support plates, and the flexible wires are uniformly distributed along the edges of the support plates at equal distance to form a flexible wire group to form a wire cage type support structure. The center of the supporting plate positioned at the top of the supporting structure is provided with an air hole for negative pressure driving, and the middle part of all middle supporting plates except the top supporting plate and the bottom supporting plate are provided with holes. The shape of the support plate may be one of a circle, a semicircle, or a polygon. Preferably, the support plates are circular, and all intermediate support plates except the top support plate and the bottom support plate are circular with circular holes in the middle.

The pre-stretched flexible chamber is obtained by stretching the initial flexible chamber in the circumferential direction. The initial flexible chamber is molded from one of silicone rubber, ecoflex, hydrogel by casting or 3D printing. The initial flexible cavity is cylindrical with one end open, the initial inner diameter of the cylindrical initial flexible cavity is smaller than the outer diameter of the supporting structure, the initial flexible cavity is prestretched to the inner diameter of the initial flexible cavity along the circumferential direction to be equal to the outer diameter of the supporting structure, the supporting structure is placed in the flexible cavity to support the flexible cavity, and then the opening of the flexible cavity is sealed, so that the negative pressure pneumatic artificial muscle driver with built-in prestretching is obtained.

Preferably, the support plate is made of one of resin, plastic, metal or wood material.

Preferably, all support plates are arranged at equal intervals up and down.

Preferably, the flexible wire is one of cotton wire, hemp wire and nylon wire, and the flexible wire is connected with the supporting plate by bonding or anchoring.

The artificial muscle driver of the invention is passively elongated and deformed, the artificial muscle driver is elongated and deformed under the action of external load, the distance between the supporting structures is increased, the flexible wires are stretched, and the flexible wires are restrained to be deformed outwards until the flexible wires are completely straightened, and the initial design length is reached, and the process is the passive elongation process of the driver.

And in the active contraction process of the driver under the action of negative pressure, the flexible cavity is contracted inwards under the action of negative air pressure, so that tension is generated in the flexible wire and acts on the supporting structure, the supporting structure is contracted, and the driving force is output.

Compared with the prior art, the invention has the following advantages:

(1) The artificial muscle driver provided by the invention is connected with the supporting structure by utilizing the inextensible flexible wire group to form a wire cage type structure, and the flexible cavity is pre-stretched along the circumferential direction by utilizing the stretchable soft material as the flexible cavity and supported by the wire cage type structure, so that certain pre-strain exists in the artificial muscle driver. In the artificial muscle contraction process under the action of negative pressure, the pre-strain in the flexible cavity is gradually released along with deformation, so that the flexible cavity is ensured not to generate wrinkling or buckling deformation, and meanwhile, the advantages of large output stress, output strain and the like of the driver are maintained.

(2) The problem of uncertainty and poor controllability of the output characteristics of the negative pressure pneumatic artificial muscle driver is solved through the idea of built-in pre-strain, and the novel negative pressure pneumatic artificial muscle with accurately described and controllable driving behavior is obtained.

Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention.

Drawings

FIG. 1 is a schematic diagram of the construction of the pre-strained negative pressure pneumatic artificial muscle driver of the present invention.

Reference numerals in the drawings:

1-supporting plate, 2-flexible wire, 3-initial flexible cavity, 4-pre-stretched flexible cavity, 5-artificial muscle driver, 6-supporting structure, 7-air hole, 8-middle opening and 9-sealing cover plate.

Detailed Description

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings, it being understood that the preferred embodiments described herein are for illustration and explanation of the present invention only, and are not intended to limit the present invention.

As shown in fig. 1, the invention provides a built-in pre-strained negative pressure pneumatic artificial muscle driver, which comprises an initial flexible cavity 3 capable of elongating and deforming and a wire cage type supporting structure 6 arranged in a pre-stretched flexible cavity 4.

The supporting structure 6 comprises at least three supporting plates 1 which are arranged in parallel from top to bottom and have the same outline, and two adjacent supporting plates 1 are vertically connected through a plurality of inextensible flexible wires 2. All flexible wires 2 have equal lengths and equal intervals between the two support plates 1, the flexible wires 2 are uniformly distributed along the edges of the support plates 1 at equal intervals to form flexible wire groups, and finally the wire cage-shaped support structure 6 is formed. The center of the top support plate is provided with an air hole 7 which is used for negative pressure driving, and the middle of all middle support plates except the top support plate and the bottom support plate are provided with holes 8. The shape of the support plate may be one of a circle, a semicircle, or a polygon. Preferably, the support plate 1 is circular, all intermediate support plates except the top support plate and the bottom support plate are circular with round holes in the middle, and a plurality of intermediate support plates are arranged at equal intervals between the adjacent support plates.

The pre-stretched flexible chamber 4 is obtained after stretching the initial flexible chamber 3 in the circumferential direction. The initial flexible chamber 3 is formed from one of silicone rubber, ecoflex, hydrogel by casting or 3D printing. The initial flexible chamber 3 is cylindrical with one end open. The initial inner diameter of the initial flexible cavity 3 is smaller than the outer diameter of the support structure 6, the initial flexible cavity 3 is prestretched along the circumferential direction to obtain a prestretched flexible cavity 4, a certain strain is prestretched inside the material along the circumferential direction, the inner diameter of the prestretched flexible cavity 4 is the same as the diameter of the support structure 6, the support structure 6 is placed in the prestretched flexible cavity 4, the prestretched flexible cavity 4 is supported, and then the prestretched flexible cavity 4 is sealed by a sealing cover plate 9, so that the built-in prestretched negative pressure pneumatic artificial muscle driver 5 is obtained. In the initial state, the artificial muscle driver will contract due to the presence of the pre-strain of the flexible cavity, such that the flexible cavity height and the support structure height are the same. The sealing cover plate 9 is made of the same material as the flexible cavity, and is made of flexible materials such as silicone rubber, ecoflex, hydrogel and the like. The sealing cover plate 9 and the pre-tensioned flexible chamber 4 may be fixedly sealed by means of an adhesive, but is not limited to this form of fixation.

The design of the wire cage structure can restrict the deformation of the flexible cavity in the passive extension or active contraction deformation process of the driver, namely the flexible wire group is always attached to the flexible cavity, the non-extension characteristic of the flexible wire converts the deformation of the flexible cavity into tensile force to act on the supporting structure, and the advantages of large output force, output deformation and the like of the driver are ensured.

The pre-stretching is carried out on the initial flexible cavity, so that the pre-strain exists in the initial flexible cavity in advance, and in the shrinkage deformation of the initial flexible cavity, the internal strain is gradually released but is not zero all the time, so that the wall surface of the flexible cavity is ensured not to be wrinkled or buckled and deformed, and stable, accurate and controllable deformation behavior is realized.

In a word, the invention utilizes the wire cage type structure to combine the stretchable deformation flexible cavity, solves the problems of uncertainty and poor controllability of the output characteristics of the negative pressure pneumatic artificial muscle driver through the idea of built-in pre-strain, obtains the novel negative pressure pneumatic artificial muscle with accurately described and controllable driving behavior, simultaneously gives consideration to the passive extension and active contraction deformation of the negative pressure pneumatic artificial muscle driver, and keeps the large output stress and output strain characteristics of the driver. The driver has compact structure and low manufacturing cost, and is beneficial to practical application of production and life.

The present invention is not limited to the preferred embodiments, and the present invention is described above in any way, but is not limited to the preferred embodiments, and any person skilled in the art will appreciate that the present invention is not limited to the embodiments described above, while the above disclosure is directed to various equivalent embodiments, which are capable of being modified or varied in several ways, it is apparent to those skilled in the art that many modifications, variations and adaptations of the embodiments described above are possible in light of the above teachings.

Claims

1. A negative pressure pneumatic artificial muscle actuator with built-in pre-strain, characterized by comprising a flexible cavity that can be stretched and deformed and a wire cage support structure disposed within the pre-stretched flexible cavity;

The support structure includes at least three support plates with the same outer contour arranged in parallel from top to bottom, and two adjacent support plates are vertically connected by a plurality of inextensible flexible wires, the lengths of all flexible wires being equal to the distance between the two support plates, and the flexible wires being evenly distributed along the edges of the support plates at equal intervals to form a flexible wire group, forming a wire cage-type support structure; an air hole is provided in the center of the support plate at the top of the support structure for use in negative pressure drive, the middle portions of all middle support plates are provided with holes, and the bottom support plate is not provided with holes;

The pre-stretched flexible cavity is obtained by stretching the initial flexible cavity along the circumferential direction; the initial flexible cavity is a cylinder with an open end, and the initial inner diameter of the cylinder is smaller than the outer diameter of the supporting structure. After the initial flexible cavity is pre-stretched along the circumferential direction until its inner diameter is equal to the outer diameter of the supporting structure, the supporting structure is placed in the flexible cavity to support the flexible cavity, and then the opening of the flexible cavity is sealed to obtain a negative pressure pneumatic artificial muscle actuator with built-in prestrain.

2. The negative pressure pneumatic artificial muscle actuator with built-in prestrain according to claim 1, wherein the support plate is one of circular, semicircular or polygonal.

3. The negative pressure pneumatic artificial muscle actuator with built-in prestrain according to claim 2, wherein the support plate is made of one of resin, plastic, metal or wood.

4. The negative pressure pneumatic artificial muscle actuator with built-in prestrain according to claim 1, wherein all the support plates are arranged at equal intervals in the upper and lower parts.

5. The negative pressure pneumatic artificial muscle actuator with built-in prestrain according to claim 1, wherein the flexible wire is selected from one of cotton thread, hemp thread and nylon thread.

6 . The negative pressure pneumatic artificial muscle actuator with built-in prestrain according to claim 5 , wherein the flexible wire is connected to the support plate by bonding or anchoring.

7. The negative pressure pneumatic artificial muscle actuator with built-in prestrain according to claim 1, wherein the initial flexible cavity is formed from silicone rubber by casting or 3D printing.

8. The negative pressure pneumatic artificial muscle actuator with built-in prestrain according to claim 1, wherein the initial flexible cavity is formed by Ecoflex through casting or 3D printing.

9. The negative pressure pneumatic artificial muscle actuator with built-in prestrain according to claim 1, wherein the initial flexible cavity is formed by hydrogel by casting or 3D printing.