Bionic earthworm soft robot based on flexible actuator

Abstract

The present invention relates to a soft robot. The purpose is to provide a bionic earthworm soft robot based on a flexible actuator, which should be able to achieve continuous movement in different deformation postures through different phase angle voltage stimulation directions, and has the characteristics of being small in size and applicable in smaller environments. The technical solution is a bionic earthworm soft robot based on a flexible actuator, characterized in that: the robot includes at least three soft driving joints connected in series, each soft driving joint includes three sheet-like flexible ionic actuators, two thin sheets connected to both ends of the three flexible ionic actuators, and a conductive electrode connected between one end of each flexible ionic actuator and the thin sheet; the three flexible ionic actuators are arranged perpendicular to the thin sheets and are respectively connected to the drive controller through wires; the periphery of the thin sheet is also provided with a one-way friction surface that is conducive to the robot crawling forward.

Description

Technical Field

[0001] The invention relates to a soft robot, in particular to a bionic earthworm soft robot based on a flexible ionic drive. Background Art

[0002] Soft robots have attracted widespread attention due to their continuous deformation achieved by variable-stiffness soft matter materials, integrated drive and execution, silent operation, and safe human-machine and environmental interaction. Inspired by the way earthworms in nature use their segmented muscles to drive displacement and achieve different postures, soft robots that imitate earthworms have been introduced. Chinese patent application CN108891496B discloses a pneumatic earthworm-like soft robot, which includes at least three single-segment structures bonded in sequence, the single-segment structure including an axial drive, an elastic outer cavity sleeved on the axial drive, and an air tube; the axial drive is a cylindrical multi-cavity structure, the outer portion of the cylinder is a corrugated structure, each corrugation is provided with a cavity, and the cavities are connected by air paths, the elastic outer cavity is an ellipsoidal cavity structure, and an air tube is provided between the axial drive and the elastic outer cavity. This soft robot is driven by gas and can crawl not only on a flat surface but also in narrow spaces such as pipes. Chinese patent application CN114918909A discloses a soft robot that mimics earthworm crawling, comprising a head component, a tail component, and a trunk component. The head component comprises an outer shell and an elastic capsule. The trunk component is an actuator formed by stacking four fiber-reinforced soft tubes. The tail component comprises an outer shell and an elastic capsule. The head component and the tail component are connected to the trunk component through their respective outer shells. Each fiber-reinforced soft tube and the elastic capsule are connected by an air hole, which can be controlled independently. The friction between the head component and the tail component and the ground is changed by switching the elastic capsule between high-pressure and low-pressure states. The common drawback of the above earthworm-like soft robots is that they are large in size and use a pneumatic source, making them inapplicable in smaller environments. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned background technology and provide a bionic earthworm soft robot based on a flexible drive. The robot should be able to achieve continuous movement in different deformation postures through different phase angle voltage stimulation directions, and has the characteristics of being small in size and can be used in smaller environments.

[0004] The technical solution of the present invention is:

[0005] A bionic earthworm soft robot based on a flexible actuator includes a drive controller connected to a power supply; the robot is characterized in that: the robot includes at least three soft drive joints connected in series, each soft drive joint includes three sheet-like flexible ionic actuators, two thin sheets connected to both ends of the three flexible ionic actuators, and a conductive electrode connected between one end of each flexible ionic actuator and the thin sheet; the three flexible ionic actuators are arranged perpendicular to the thin sheets and are respectively connected to the drive controller through wires; the periphery of the thin sheet is also provided with a one-way friction surface that is conducive to the robot crawling forward.

[0006] Among the three flexible ion-type actuators, the angles between the planes of two adjacent flexible ion-type actuators are acute angles.

[0007] The one-way friction surface is composed of a plurality of burrs with the same extending direction, and the extending direction is opposite to the forward direction of the robot.

[0008] The angle between the extending direction of the burr and the axis of the forward direction of the robot is less than 50 degrees.

[0009] Each flexible ionic actuator consists of an intermediate layer and a PEDOT:PSS electrode layer connected to the two surfaces of the intermediate layer. Each conductive electrode includes two mutually insulated electrodes, and these two electrodes are respectively connected to the two electrode layers to connect to different voltages. The intermediate layer is an artificial muscle composed of carboxylated cellulose nanowhiskers, ionic liquid EMT and graphene. It has strong mechanical properties, and the Young's modulus in the test can reach 65Mpa.

[0010] The acute angle is 60 degrees.

[0011] The sheets are thin glass fiber discs.

[0012] The drive controller includes an STM32 single-chip microcomputer, a 5V regulated power supply, a voltage stabilization module, a power amplifier module and a control switch.

[0013] The working principle of the present invention is: in the initial state, the three driving joints are normally unfolded, and the one-way friction surfaces around the three thin sheets are in a ground-contacting state; in the working state, after power is turned on, the three driving joints contract perpendicular to the plane direction of the thin sheet 1 (i.e., the moving direction), and under the action of the one-way friction surface around the thin sheet and the ground, each driving joint together with the thin sheet at the rear end (the left end in the figure) (this is the moving end) contracts a certain distance toward the thin sheet at the front end (the right end in the figure) (this is the fixed end); then, the three driving joints are powered off and restored to their original shape, that is, each driving joint begins to expand, and under the action of the one-way friction surface around the thin sheet and the ground, the thin glass fiber circular plate at the front end becomes the moving end and extends forward, while the thin glass fiber circular plate at the rear end serves as the fixed end and does not move, and a movement cycle ends; repeating this cycle can realize continuous displacement of the soft robot in the horizontal direction. In addition, by controlling the voltage input direction of electrodes at different positions within each joint, continuous deflection of different actuators along specific directions can be achieved, such as left or right deflection of the joint, head tilt, and other action effects, thereby realizing the description of different postures in three-dimensional space.

[0014] Compared with existing soft robots, the robot has the following advantages:

[0015] 1. The soft robot material uses ionic artificial muscle, which is light, environmentally friendly, and safe for human-computer interaction.

[0016] 2. Simple structure, low driving voltage and low cost.

[0017] 3. It is small in size and can work in dangerous and narrow environments (such as testing in small pipes) after adding sensors, so it has practical value.

[0018] 4. Achieve horizontal movement while utilizing the continuous deformation feature to achieve changes in different postures, broadening its application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of the three-dimensional structure of an embodiment of the present invention.

[0020] Figure 2 Schematic diagram of the cross-sectional structure of the sheet in an embodiment of the present invention.

[0021] Figure 3 yes Figure 2 Schematic diagram of the enlarged structure of part A (showing the one-way friction surface structure).

[0022] Figure 4 Schematic diagram of the electrically driven deformation of a single driven joint in an embodiment of the present invention.

[0023] Figure 5Schematic diagram of the forward motion principle of the bionic earthworm soft robot in an embodiment of the present invention (top view); the numbers I, II, III, and IV in the figure are position marks of the various slices in the robot.

[0024] Figure 6 Schematic diagram of different postures of each flexible ionic actuator when the bionic earthworm soft robot in an embodiment of the present invention twists left and right.

[0025] Numbers in the figure: 1, thin sheet; 2, flexible ionic actuator; 3, conductive electrode; 4, burr. DETAILED DESCRIPTION

[0026] The following further describes the embodiments of the present invention in conjunction with the accompanying drawings. In particular, the following examples will help professionals in the field better understand the present invention, but they do not limit the scope of protection of the present invention.

[0027] like Figure 1 The bionic earthworm soft robot based on a flexible actuator is shown; this embodiment consists of three cylindrical soft-actuated joints connected in series. In the non-working state, the three soft-actuated joints are normally unfolded. A single soft-actuated joint consists of three sheet-shaped flexible ionic actuators (abbreviated as ionic actuators, the same below) connected to conductive electrodes 3 and two thin sheets 1 (preferably thin glass fiber discs) installed (preferably glued) at both ends of the ionic actuators. The planes of the two ionic actuators are fixed on the thin sheets at a 60-degree phase angle. Adjacent soft-actuated joints can be glued together (the two thin sheets are glued together) to form an earthworm-shaped soft robot body.

[0028] Furthermore, the two thin sheets bonded with glue between adjacent soft-body drive joints can be simplified into one thin sheet; at this time, the front and back planes of the thin sheet are respectively connected to one end of the three ionic drives, and the planes of the three ionic drives connected to each plane are arranged at a 60-degree phase angle.

[0029] Each ionic actuator (see CN113462032A) is composed of an intermediate layer and a PEDOT:PSS electrode layer connected to the two surfaces of the intermediate layer; the intermediate layer is an artificial muscle composed of carboxylated cellulose nanowhiskers, ionic liquid EMT and graphene. The deformation caused by the ionic actuator being energized becomes the crawling power of the bionic earthworm soft robot. The deformation caused by the energization is the bending caused by the ionic actuator being energized (the two electrode layers of each ionic actuator are connected to different voltages, the outer electrode layer connected to the positive voltage expands, and the inner electrode layer connected to the negative voltage contracts, thereby causing the ionic actuator to bend). When the ionic actuator is energized, the three ionic actuators on each soft-drive joint simultaneously bend and protrude in the outer diameter direction (such as Figure 4(As shown in Figure B), the length of the soft-actuated joint is shortened; when the ionic drive is powered off, the bending deformation disappears and the length of the soft-actuated joint is restored.

[0030] Since the bionic earthworm soft robot crawls on the ground, the plane of the sheet is basically perpendicular to the bottom surface during crawling; in order to enable the bionic earthworm soft robot to move forward, the present invention arranges a one-way friction surface around the edge of each sheet, and the one-way friction surface is composed of a plurality of burrs or bevel teeth with the same extension direction, and the extension direction is facing away from the forward direction of the robot (the one-way friction surface can also be a plurality of tentacles evenly arranged on the circumferential edge of the sheet, and the ground-contacting side of each tentacle is provided with a plurality of burrs with the same extension direction); thereby, when the robot crawls on the ground, the one-way friction surface can directly press against the ground; at the same time, it is important that the burrs on the one-way friction surfaces of all sheets are in the same direction, all facing backward ( Figure 2 、 Figure 3 As shown, it is tilted toward the left side) and maintains an acute angle with the axis (HR) of the sheet (i.e., the angle B between the rear end surface of the burr and the axis of the sheet; preferably less than 50 degrees), so that the friction generated when the sheet slides against the ground in the front and back directions (front end, the right end of the sheet; rear end, the left end of the sheet) is different (the friction generated when the sheet moves backward against the ground is large; the friction generated when the sheet slides along the ground when it moves forward is small); in this way, when the ionic drive is repeatedly powered on and off to produce a deformation cycle, the robot can gradually crawl forward (to the right end) on the ground.

[0031] Electrically driven deformation of soft-body driven joints Figure 4As shown in the figure (the "+" and "-" symbols in the figure represent voltage polarity); taking a single soft-actuated joint as an example, a single joint contains three ionic actuators. In the initial state A, no power is applied, and the three flexible ionic actuators (hereinafter referred to as actuators) unfold normally; in the intermediate state B, the outer electrode layers of the three ionic actuators are connected to a positive voltage and the inner electrode layers are connected to a negative voltage, and the three ionic actuators are deformed respectively, and the planes of the three ionic actuators are bent toward the outer diameter (drum-shaped protrusion), which shortens the length of the single joint (the length of the horizontal plane projection is shortened); because the friction between the unidirectional friction surfaces of the thin plates at both ends of the single joint and the ground is different, the rear end thin plate (the fixed unidirectional friction surface on it moves along the ground with low friction) becomes the moving end, and the front end thin plate (the fixed unidirectional friction surface on it moves against the ground with high friction) cannot move and becomes the fixed end. At this point, the displacement of the moving end of a single ionic actuator on the ground is Δx. At the end of state C, the three ionic actuators deform again due to power outage and begin to return to their original state (extended). The moving ends at the front and rear ends become fixed ends, while the fixed end at the front ends becomes the moving end. The displacement of the moving ends perpendicular to the circular glass plate is Δx. Clearly, the distance advanced by a single joint in the previous cycle is Δx. The distance advanced by the entire bionic earthworm soft robot is the product of Δx and the number of joints. By contracting or expanding the joints, the robot can simulate the earthworm's forward motion, achieving different postures and horizontal displacements. By controlling the voltage, charge and discharge frequency, and the power-on sequence of the three ionic actuators (for example, the first joint on the left end is energized to contract; then the second joint is energized to contract, while the first joint on the left end is de-energized to return to its original state; then the third joint is energized to contract, while the second joint is de-energized to return to its original state; finally, the third joint is de-energized to return to its original state; and so on, the forward movement distance is Δx, completing a crawling cycle). The robot's movement speed can be effectively controlled.

[0032] Figure 5This is another schematic diagram of a forward motion cycle in this embodiment. In the figure, I, II, III, and IV represent the starting positions of the four thin slices. In each cycle, the three soft-actuated joints are energized and contracted simultaneously, and then de-energized and restored simultaneously. The soft robot crawls horizontally for a distance of 3Δx. Horizontal motion is achieved by controlling the voltage sequence of the ionic actuators and the driven joints. The three motion states of the bionic earthworm soft robot are shown in the figure: in the starting state A, the three soft-driven joints of the robot are normally unfolded; in the intermediate state B, the three soft-driven joints receive the electrical stimulation signal of the power-on sequence one and begin to bend and deform respectively. At this time, the right end of each soft-driven joint is the fixed end, and the left end is the moving end. The flexible ion drive contracts perpendicular to the glass fiber cross-section (i.e., the moving direction), so that each drive joint moves a distance Δx toward the fixed end; in the ending state C, the three soft-driven joints receive the electrical stimulation signal of the power-on sequence two, and the drive begins to restore its original shape after the power is cut off. The left end of each soft-driven joint is the fixed end, and the right end is the moving end, that is, the three drive joints expand toward the right end, and the total expansion displacement is 3Δx, which is the horizontal displacement of the robot. In this way, the robot completes a cycle of work.

[0033] Figure 6 This is a schematic diagram of the robot's different spatial postures (the "+" and "-" symbols in the figure indicate voltage polarity). By controlling the voltage direction, the three drivers in each joint are energized in different directions or at different voltages, causing the joint to deviate left or right, thereby causing different driven joints to contract or expand in different postures. Figure 6 The left deviation in the figure L is the combined result of the fact that the sheet 2B is bent in the outer diameter direction, while the sheets 2A and 2C are bent in the inner diameter direction. Figure 6 The R figure in the figure is right-biased, a result of the combined effect of sheet 2B curving inward, while sheets 2A and 2C curvature outward. This allows the robot to achieve different postures while simulating the earthworm's forward motion.

[0034] The drive controller (existing technology) includes an STM32 single-chip microcomputer, a 5V regulated power supply, a voltage stabilizing module, a power amplifier module and a control switch.

[0035] When the control switch is closed, the 5V power supply starts to supply power for system operation, generating an adjustable voltage periodic AC signal in the STM32. With the help of the voltage stabilization module and the power amplifier module, it is converted into a usable positive and negative 1.5V driving voltage. This voltage provides electrical stimulation to the flexible actuator, and the stimulated flexible driving material will deform in different directions. Through the above-mentioned structural design, the joints will contract or expand, so that the robot can simulate the movement of the earthworm and achieve different postures and horizontal displacements.

[0036] An embodiment of the present invention is described above. In particular, relevant professionals can make deformation or modifications within the scope of rights, which should also be within the scope of protection of the present invention.

Claims

1. A bionic earthworm soft robot based on a flexible actuator, comprising a drive controller connected to a power supply; characterized in that: The robot comprises at least three soft drive joints connected in series, each soft drive joint comprising three sheet-like flexible ionic actuators (2), two thin sheets (1) and three conductive electrodes (3); the two thin sheets are connected to the two ends of the three sheet-like flexible ionic actuators, and the three conductive electrodes are respectively connected between the left ends of the three flexible ionic actuators and the thin sheets; the two thin sheets of adjacent soft drive joints are connected as a whole; the three flexible ionic actuators are arranged perpendicular to the thin sheets and are respectively connected to the drive controller via wires; and a one-way friction surface is also provided around the thin sheets to facilitate the robot's crawling forward.

2. The bionic earthworm soft robot based on a flexible actuator according to claim 1, characterized in that: The two thin sheets of adjacent soft-body driven joints are simplified into one thin sheet.

3. The bionic earthworm soft robot based on a flexible actuator according to claim 2, characterized in that: Among the three flexible ion-type actuators, the angles between the planes of two adjacent flexible ion-type actuators are acute angles.

4. The bionic earthworm soft robot based on a flexible actuator according to claim 3, characterized in that: The one-way friction surface is composed of a plurality of burrs (4) with the same extension direction, and the extension direction faces away from the forward direction of the robot.

5. The bionic earthworm soft robot based on a flexible actuator according to claim 4, characterized in that: The angle between the extending direction of the burr and the axis of the forward direction of the robot is less than 50 degrees.

6. The bionic earthworm soft robot based on a flexible actuator according to claim 5, characterized in that: Each flexible ionic actuator consists of an intermediate layer and a PEDOT:PSS electrode layer connected to the two surfaces of the intermediate layer. Each conductive electrode includes two mutually insulated electrodes, and these two electrodes are respectively connected to the two electrode layers to connect to different voltages. The intermediate layer is an artificial muscle composed of carboxylated cellulose nanowhiskers, ionic liquid EMT and graphene.

7. The bionic earthworm soft robot based on a flexible actuator according to claim 6, characterized in that: The acute angle is 60 degrees.

8. The flexible actuator-based bionic earthworm soft robot according to claim 7, characterized in that: The sheets are thin glass fiber discs.

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