CN108000557B

CN108000557B - Layer blocking variable stiffness structure based on electrostatic principle and preparation method thereof

Info

Publication number: CN108000557B
Application number: CN201711261561.7A
Authority: CN
Inventors: 张进华; 洪军; 王韬; 李玥
Original assignee: Xian Jiaotong University
Current assignee: Xian Jiaotong University
Priority date: 2017-12-04
Filing date: 2017-12-04
Publication date: 2020-08-18
Anticipated expiration: 2037-12-04
Also published as: CN108000557A

Abstract

The invention discloses a layer blocking variable stiffness structure based on an electrostatic principle and a preparation method thereof. The method is different from the traditional particle blocking variable stiffness method, does not need a large number of particles and a heavy pneumatic device, has obvious advantages in variable stiffness performance, is easy to integrate an electrical control system, has more obvious advantages compared with the traditional particle blocking mode at present, provides a new idea for the variable stiffness requirement of the soft robot, and has great application prospects in the field of soft robots.

Description

Layer blocking variable stiffness structure based on electrostatic principle and preparation method thereof

Technical Field

The invention belongs to the technical field of variable stiffness, relates to a novel layer blocking variable stiffness method based on an electrostatic principle, and particularly relates to a layer blocking variable stiffness structure based on the electrostatic principle and a preparation method thereof.

Background

The soft robot has strong adaptability to the environment and high interactive safety, has non-trivial application potential in various fields such as medical treatment, military, industry and the like, and has become an popular research field at present. The soft robot is generally made of super elastic material, the body is soft, and has infinite freedom, which results in that the rigidity of the robot body is not enough to meet the use requirement under the condition of resisting corresponding force, which severely limits the development of the soft robot, therefore, the rigidity change of the soft robot is controlled to be one of important technologies for breaking through the current development bottleneck. Aiming at the variable stiffness research in the field of soft robots, the blocking variable stiffness method is widely applied to the requirements of the soft robots for variable stiffness because of the advantages of simple design, low cost, no need of temperature dependence and the like.

The blocking variable stiffness method mainly comprises particle blocking and layer blocking, researchers have designed a plurality of impressive structures by utilizing a particle blocking technology, and realize functions which cannot be realized by a plurality of soft robots incapable of changing stiffness, and soft grippers based on the blocking variable stiffness can grab objects in various shapes, have the capabilities of high deformation in a fluid state and greatly increasing solid state stiffness, and cannot generate larger volume change, but the realization of the particle blocking variable stiffness needs a large amount of blocking particles, and the interference of most mechanical properties is unknown. In addition, when the soft body robot system works in a narrow working space, for example, for invasive surgical instruments with high requirements on dexterity, soft snake-shaped robot navigation and soft body rehabilitation hands, the problems of heavy weight, inaccurate control, negative pressure extraction by vacuum equipment and the like exist in the rigidity change caused by particle blockage.

The layer blocking variable stiffness technology has shown great application potential in many fields such as soft robots, limb rehabilitation, multifunctional interfaces, building structures and the like, but the pneumatic layer blocking technology also has the problem that a vacuum device is required to extract negative pressure. Compared with the prior art, the novel layer blocking variable stiffness method based on the electrostatic principle has larger advantages and is more suitable for occasions with high requirements on overall flexibility, control precision and weight.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a layer blocking variable stiffness structure based on an electrostatic principle and a preparation method thereof.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

the layer blocking variable-stiffness structure based on the electrostatic principle comprises a substrate flexible electrode, a positive electrode material layer and a negative electrode material layer which are identical in structure, wherein the flexible electrode is embedded in the positive electrode material layer and the negative electrode material layer respectively, the surfaces of the positive electrode material layer and the negative electrode material layer are in close contact, and when direct-current voltage is applied, friction can be generated between the positive electrode material layer and the negative electrode material layer through electrostatic force to resist relative movement.

The invention further improves the following steps:

the flexible electrode adopts aluminum foil.

The whole structure is formed by laminating a plurality of anode material layers and cathode material layers, so that when direct-current voltage is applied, friction can be generated between the anode material layers and the cathode material layers at the joint through electrostatic force.

And insulating protective layers are arranged on the surfaces of the positive electrode material layer and the negative electrode material layer.

The positive electrode material layer and the negative electrode material layer are made of carbon grease.

The insulation protective layer is a PI film adhesive tape adhered on the surface of the carbon grease.

A method for preparing a layer blocking variable stiffness structure based on an electrostatic principle comprises the following steps:

step 1: pasting an aluminum foil on one end of the paper as an access flexible electrode;

step 2: placing the cut mask on paper;

and step 3: uniformly coating carbon grease on the surface of the paper, taking down the mask after the carbon grease is coated, and adhering a PI film adhesive tape to obtain a material layer;

and 4, step 4: repeating the steps 1-3 to manufacture a plurality of material layers as required; the material layers are arranged in a laminated mode, and the material layers connected into the electrodes are arranged at intervals, so that when direct-current voltage is applied, friction can be generated between the positive electrode material layer and the negative electrode material layer at the connected positions through electrostatic force.

Compared with the prior art, the invention has the following beneficial effects:

the novel layer blocking variable stiffness method based on the electrostatic principle can adjust the stiffness change of the structure by changing the external voltage, so that the control is more convenient, and different stiffness controllable ranges can be realized by applying different insulating materials. In addition, the invention does not need to use blocking particles and an air pump to extract negative pressure, thereby further simplifying the design of the whole structure. Besides the realization of wide-range rigidity change, the novel layer blocking variable rigidity method based on the electrostatic principle has the advantages of light weight, simple structure, low manufacturing cost, short manufacturing period and the like, and provides a new solution for the rigidity change of the soft robot.

Drawings

FIG. 1 is a schematic diagram of modeling electrostatic layer blocking theory;

FIG. 2-a is a schematic view of an exemplary structure A for blocking an electrostatic layer;

FIG. 2-B is a schematic view of an exemplary electrostatic layer blocking structure B;

FIG. 2-C is a schematic view of an exemplary electrostatic layer blocking structure C;

FIG. 2-D is a schematic view of an exemplary structure D for blocking an electrostatic layer;

FIG. 3 is a theoretical graph of electrostatic force;

FIG. 4-a is a graph comparing the tensile stiffness and the bending stiffness in the initial state;

FIG. 4-b is a graph comparing the tensile stiffness and the bending stiffness for extracting the negative pressure deflection stiffness;

FIG. 4-c is a graph comparing the tensile stiffness and the bending stiffness as a function of the electrostatic principle.

Wherein: 1-a layer of negative electrode material; 2-a layer of positive electrode material; 3-a flexible electrode; f-external force; m-outer torque.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

referring to fig. 1 and 2, the layer blocking variable stiffness structure based on the electrostatic principle of the invention comprises a negative electrode material layer 1 connecting a positive electrode and a negative electrode, a positive electrode material layer 2, a flexible electrode 3 embedded in the material layer, and a direct current voltage capable of being controlled to be output. When a direct current voltage is applied, charges on the electrodes can be accumulated due to a capacitance effect, then the electrodes with different charges can attract each other according to the coulomb law, and the electrostatic force can generate friction between the two material layers to resist relative movement, and meanwhile, the aim of changing the rigidity of the whole structure is fulfilled. Fig. 2-a, fig. 2-b, fig. 2-c, fig. 2-d show the typical A, B, C, D four arrangements of electrostatic layer blocking, with the layers of material of the access electrodes arranged in positive and negative spacing.

The principle of the invention is as follows:

as shown in fig. 1, the layer blocking variable stiffness structure based on the electrostatic principle of the present invention can be used for controlling the stiffness of a soft robot, and solves the problem of insufficient stiffness of the soft robot. The invention comprises the improvement of the prior variable stiffness technology, the realization mode of the variable stiffness does not depend on the air pump to pump negative pressure, does not need to block particles, and realizes the stiffness change only by further converting the electrostatic force between the charged material layers into the friction force.

As shown in fig. 3, the distance d between the electrostatic force F and the material layer is exponentially decreasing. When the distance between two electrode plates is twice that between the other two electrode plates, the relationship of the electrostatic force is one fourth, and the characteristic enables the design to be only needed to consider the action relationship of the two adjacent layers.

The working process of the invention is as follows:

as shown in fig. 4, fig. 4-a is an initial state, fig. 4-b is a drawing negative pressure variable stiffness, fig. 4-c is a variable stiffness through an electrostatic principle, and under three different conditions, the tensile stiffness and the bending stiffness of the same structure present different principles and states, fig. 4-c applies the variable stiffness soft body structure of the present invention, when a direct current voltage is applied to the flexible electrode 3, charges on the electrode will be accumulated due to a capacitance effect, then the electrodes with opposite charges will attract each other according to the coulomb law, and the electrostatic force will generate friction between the two material layers, and under the action of an external force and a bending moment, the electrostatic layer blocking structure will resist relative movement, and at the same time, the purpose of changing the stiffness of the whole structure is achieved.

The rigidity is adjustable by adopting a mode of generating friction-electrostatic layer interference between materials, in order to realize blocking variable rigidity, layers of the materials are extruded together through electrostatic force, a vacuum environment is not required to be provided, and an electronic control system is easier to integrate compared with a gas circuit control system, so that the complexity of design is reduced to a great extent, and the overall flexibility is improved.

The upper limit of the pressure that can be provided by the present invention depends on the external voltage and the dielectric constant of the insulating material as well as the structural design parameters. The flexible electrode 3 is embedded in the flexible negative electrode material layer 1 and the positive electrode material layer 2 with insulating capability; the anode material layer 1 and the cathode material layer 2 have a typical distribution form shown in fig. 2, and are expandable according to the arrangement rule. The invention can control the rigidity change of the whole structure by controlling the external voltage. The invention is not limited to the field of soft robots, and can realize rigidity change in any occasions where direct current voltage can be provided and rigidity change is needed.

The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A layer blocking variable stiffness structure based on an electrostatic principle is characterized by comprising a substrate flexible electrode (3), a positive electrode material layer (2) and a negative electrode material layer (1) which are identical in structure, wherein the flexible electrode (3) is embedded in the positive electrode material layer (2) and the negative electrode material layer (1) respectively, the surfaces of the positive electrode material layer (2) and the negative electrode material layer (1) are in close contact, and when a direct-current voltage is applied, friction can be generated between the positive electrode material layer (2) and the negative electrode material layer (1) through electrostatic force to resist relative movement;

the flexible electrode (3) adopts aluminum foil;

the whole structure is formed by laminating a plurality of anode material layers (2) and cathode material layers (1), so that when direct-current voltage is applied, friction can be generated between the anode material layers (2) and the cathode material layers (1) at the joint through electrostatic force.

2. The structure of layer blocking variable stiffness based on the electrostatic principle as claimed in claim 1, wherein the surfaces of the positive electrode material layer (2) and the negative electrode material layer (1) are further provided with an insulating protective layer.

3. The electrostatic principle based layer blocking variable stiffness structure according to claim 2, wherein the positive electrode material layer (2) and the negative electrode material layer (1) are carbon grease.

4. The structure of claim 3, wherein the insulating protective layer is a PI film adhesive tape adhered on the surface of the carbon resin.

5. A preparation method of a layer blocking variable stiffness structure based on an electrostatic principle is characterized by comprising the following steps:

step 2: placing the cut mask on paper;

and 4, step 4: repeating the steps 1-3 to manufacture a plurality of material layers as required; the material layers are arranged in a laminated mode, and the material layers connected into the electrodes are arranged at intervals, so that when direct-current voltage is applied, friction can be generated between the positive electrode material layer (2) and the negative electrode material layer (1) at the connected positions through electrostatic force.