Imitation eel robotic fish based on dielectric elastomer

Abstract

The invention relates to the technical field of soft robots, and particularly discloses an eel-imitating robotic fish based on dielectric elastomers, which comprises five connected pipe joint type dielectric elastomer drivers, a head, a tail handle and a tail fin, the head part is connected with one end of the pipe joint type dielectric elastomer driver, the tail handle is connected with the other end of the pipe joint type dielectric elastomer driver, and the tail fin is connected with the tail handle; the pipe joint type dielectric elastomer driver is composed of circular frames, a central elastic plate, dielectric elastomers and electrodes, the circular frames are divided into a first circular frame and a second circular frame and are of a male and female structure, and the central elastic plate is used for connecting the first circular frame and the second circular frame and is connected with the dielectric elastomers. And the dielectric elastomer is wound on the circular frame I and the circular frame II. The eel-imitating robotic fish based on the dielectric elastomer shows remarkable advantages in the aspects of propelling performance, flexibility, noise control and the like, and is suitable for various application scenes such as seabed detection, maintenance inspection and the like.

Description

Technical Field

[0001] The invention relates to the technical field of soft robots, in particular to an eel-like robotic fish based on a dielectric elastomer. Background Art

[0002] The demand for underwater robots is increasing in the fields of marine biological ecological surveys, seabed exploration, maintenance and inspection of water equipment, etc. With the advancement of science and technology, underwater robots have become a research field that attracts great attention from researchers. However, most existing underwater robots use rigid structures and motor drives, which brings a series of challenges and limitations:

[0003] High noise problem:

[0004] Traditional underwater robots mostly use propeller propulsion systems driven by electric motors. This propulsion method inevitably generates mechanical noise, which affects biological activities in the underwater environment and may interfere with the accuracy of scientific research.

[0005] Large structure and low efficiency:

[0006] Due to its fixed mechanical structure, the rigid robot fish has poor flexibility in the complex and changeable underwater environment. In addition, when the screw is exposed in the water and rotates, it is easy to be entangled by marine organisms, resulting in low propulsion efficiency and the risk of environmental damage.

[0007] Difficulty reproducing natural movements:

[0008] Most fish-like robots reproduce the swimming movements of fish through motors and cranks, but these robots have high body rigidity and are difficult to imitate the soft and flexible movements of real fish. Therefore, they cannot fully exert the original propulsion performance of organisms, limiting their effectiveness in practical applications.

[0009] Poor environmental adaptability:

[0010] Traditional rigid robots show poor adaptability when facing complex underwater terrain and water flow changes. However, soft robots have higher flexibility and environmental adaptability due to their material properties and design principles.

[0011] In order to solve the above problems, researchers have begun to try to develop soft robots using flexible materials in recent years. Such robots are driven by intelligent materials (such as dielectric elastomers) and have the advantages of silent drive, simplified body structure, high flexibility and high environmental adaptability. In particular, dielectric elastomers, as a new type of intelligent soft material, have the following characteristics:

[0012] Low elastic modulus: allows the material to deform more under lower stress.

[0013] Large deformation range: It can achieve significant deformation under high voltage and provide greater driving force.

[0014] High energy density: The energy that can be stored and released per unit volume is high, which improves driving efficiency.

[0015] Fast response speed: The deformation process can be completed in a short time, which improves the control accuracy and response speed.

[0016] Although dielectric elastomer actuators have many advantages, the research on their application in underwater robots is still in the development stage. Currently, how to optimize the design of dielectric elastomer actuators and their integration in soft robots is one of the research hotspots in this field.

[0017] Based on the above background, the present invention proposes a design of a bionic eel robot fish based on dielectric elastomer, aiming to overcome the problems of high noise, low efficiency, rigid structure, etc. in the prior art, and provide an efficient, flexible and environmentally friendly underwater robot solution. Summary of the invention

[0018] The purpose of the present invention is to propose an eel-like robotic fish based on a dielectric elastomer. Through a bionic design scheme based on an eel, the problems of high noise, low efficiency, rigid structure, etc. existing in the prior art are overcome, and an efficient, flexible, and environmentally friendly underwater robot solution is provided.

[0019] To achieve the above-mentioned purpose, the present invention proposes an eel-like robotic fish based on dielectric elastomer, comprising 5 connected tube-segment dielectric elastomer drivers, a head, a caudal stalk and a caudal fin, characterized in that the head is connected to one end of the tube-segment dielectric elastomer driver, the caudal stalk is connected to the other end of the tube-segment dielectric elastomer driver, and the caudal fin is connected to the caudal stalk; the tube-segment dielectric elastomer driver is composed of a circular frame, a central elastic plate, a dielectric elastomer and an electrode, the circular frame is divided into circular frame one and circular frame two, and the circular frame one and the circular frame two are male and female structures.

[0020] Preferably, the circular frame has a diameter of 30 mm, a thickness of 3 mm, and a pre-stretching ratio of 4 times in the axial direction and 3 times in the circumferential direction.

[0021] Preferably, the central elastic plate is used to connect the circular frame one and the circular frame two, and the dielectric elastomer is wound around the circular frame one and the circular frame two.

[0022] Preferably, the central elastic plate has a length of 30 mm, a width of 10 mm and a thickness of 0.2 mm.

[0023] Preferably, the electrode is made of carbon powder and is coated on the inner side of the dielectric elastomer.

[0024] Preferably, the circular frame is made of carbon fiber reinforced plastic (CFRP) material, and the central elastic plate is made of polyethylene terephthalate (PET) material.

[0025] Preferably, the head, the caudal peduncle and the caudal fin are designed as smooth structures, and the caudal fin imitates the shape of the caudal fin of an eel and is made of 0.2 mm thick CFRP material.

[0026] Preferably, the operating voltage of the dielectric elastomer driver is 4.5 kV sinusoidal alternating current, the frequency range is 0.1 Hz to 10.0 Hz, and the optimal driving frequency is 1.5 Hz.

[0027] Preferably, the eel robot fish has a total length of 273 mm, a height of 35.3 mm, and a total weight of 26.83 g.

[0028] Preferably, it also includes a central pattern generator CPG control system, and the CPG control system is used for self-excitation to generate rhythmic control signals, distributed control and dynamic system parameter adjustment mechanism.

[0029] Therefore, the present invention proposes an eel-like robotic fish based on a dielectric elastomer, and its beneficial effects are as follows:

[0030] (1) Low-noise operation: Since dielectric elastomer is used as the driving material, the driving function is achieved through deformation under high voltage, avoiding the mechanical noise problem caused by traditional motor drive. This enables the robot fish of the present invention to operate silently in an underwater environment, and is particularly suitable for marine biological ecological surveys and scientific research that require a quiet environment.

[0031] (2) High flexibility and adaptability: Dielectric elastomer actuators have the advantages of large deformation range, high energy density, and fast response speed, which endow the robot fish with high flexibility and agility. This feature enables the robot fish to imitate the movements of real fish and improve its maneuverability and adaptability in complex underwater environments.

[0032] (3) Simplified structural design: Compared with the traditional rigid structure robot fish, the present invention adopts a lightweight tube-type dielectric elastomer driver and a detachable connection mechanism, which simplifies the overall structural design, reduces weight and volume, and thus reduces manufacturing costs and maintenance difficulties; at the same time, when a module fails, it can be easily replaced and repaired separately, improving the reliability and maintenance efficiency of the system.

[0033] (4) Optimized fluid dynamics design: The head and tail fin of the robot fish have been carefully designed to mimic the natural shape of the eel, reducing unnecessary fluid resistance and further improving swimming efficiency. In particular, the design of the tail fin is based on the actual shape of the eel, which helps to improve propulsion and stability.

[0034] (5) Intelligent control mechanism: The central pattern generator (CPG) control system is introduced to realize the self-excitation generation of rhythmic control signals, distributed control and dynamic system parameter adjustment mechanism. It does not require complex kinematics and inverse kinematics calculations, simplifies the control process and improves the response speed and accuracy of the system.

[0035] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the overall structure of an eel-like robotic fish based on a dielectric elastomer according to the present invention;

[0037] Figure 2 It is a schematic structural diagram of a tube-segment dielectric elastomer actuator in a dielectric eel-like robotic fish based on a dielectric elastomer according to the present invention;

[0038] Figure 3 This is a schematic diagram of the circular frame series structure in the present invention;

[0039] Figure 4 This is a schematic diagram of the size parameters of the central elastic plate and circular frame of the tube-type dielectric elastomer driver of the present invention; wherein, Figure 4 a in the figure is a schematic diagram of the size parameters of the central elastic plate. Figure 4 b in the figure is a schematic diagram of the circular frame size parameters;

[0040] Figure 5 This is a schematic diagram of the structure of an eel-like robotic fish head based on a dielectric elastomer according to the present invention;

[0041] Figure 6 This is a schematic diagram of the structure of a mechanical fish tail handle and tail fin of an eel imitating based on a dielectric elastomer according to the present invention;

[0042] Figure 7 is the swimming speed of the robotic fish at each frequency in the embodiment of the present invention;

[0043] Figure 8 This is the swimming mode of the robot fish at a frequency of 1.5 Hz in an embodiment of the present invention;

[0044] Fig. 9 Schematic diagram of displacement measurement points of the robot fish in an embodiment of the present invention;

[0045] Fig.10is the displacement of each measurement point of the robot fish relative to time in the embodiment of the present invention.

[0046] Reference numerals

[0047] 1. Head; 2. Tubular-segment dielectric elastomer driver; 21. Dielectric elastomer; 22. Electrode; 23. Central elastic plate; 24. Circular frame; 241. Circular frame one; 242. Circular frame two; 3. Caudal stalk; 4. Caudal fin. DETAILED DESCRIPTION

[0048] In order to make the technical solutions, advantages and purposes of the present invention clearer, the technical solutions of the embodiments of the present invention are clearly and completely described below. The described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of this application.

[0049] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0050] Embodiment 1

[0051] like Figure 1 As shown, the present invention provides an eel-like robotic fish based on dielectric elastomer, comprising five connected tube-segment dielectric elastomer actuators 2, a head 1, a caudal peduncle 3 and a caudal fin 4, wherein the head 1 is connected to one end of the tube-segment dielectric elastomer actuator 2, the caudal peduncle 3 is connected to the other end of the tube-segment dielectric elastomer actuator 2, and the caudal fin 4 is connected to the caudal peduncle 3.

[0052] like Figure 2-3As shown, the tube-segment dielectric elastomer driver 2 is composed of a circular frame 24, a central elastic plate 23, a dielectric elastomer 21 and an electrode 22. The circular frame 24 is divided into a circular frame 1 241 and a circular frame 242. The circular frame 1 241 and the circular frame 242 are male-female structures, which are convenient for the installation and removal of the circular frame 24. When damage occurs, the damaged part can be easily replaced. The dielectric elastomer 21 is wound on the circular frame 1 241 and the circular frame 242, and the circular frame 1 241 and the circular frame 242 are connected by the central elastic plate 23; the electrode 22 is composed of carbon powder and is applied to the inner side of the dielectric elastomer 21. The manufacturing method is to coat the electrode with carbon powder on the prestressed dielectric elastomer 21, and then wind the electrode on the circular frame 24. The central elastic plate 23 is made of polyethylene terephthalate PET material, which has the rigidity to maintain compressive stress and the flexibility to increase left and right bending; the circular frame 24 is made of carbon fiber reinforced plastic CFRP material, which has good mechanical properties, high tensile strength, good rigidity, and excellent impact resistance.

[0053] From the perspective of biomimicry, the diameter of the circular frame 24 is 30 mm, which is equal to the diameter of an ordinary electric eel, and the thickness is 3 mm, which is sufficient to adhere the dielectric elastomer 21. Figure 4 As shown, the dimension parameters of the dielectric elastomer 21 and the dimension parameters of the circular frame 24 are shown in Table 1, and the tube-segment type dielectric elastomer driver 2 is finally completed.

[0054] Table 1 Dimensions of tube-type dielectric elastomer actuators

[0055] Axial pre-tensioning Circumferential pre-stretching l(mm) w(mm) t(mm) d(mm) s(mm) Elongation ratio 4 Elongation ratio 3 30 10 0.2 30 3

[0056] Wherein, l represents the length of the central elastic plate 23 , w represents the width of the central elastic plate 23 , t represents the thickness of the central elastic plate 23 , d represents the diameter of the circular frame 24 , and s represents the thickness of the circular frame 24 .

[0057] like Figure 5-6 As shown, the head 1, caudal peduncle 3 and caudal fin 4 of the robotic fish are designed as smooth structures, which will not produce unnecessary fluid resistance; as for the caudal fin 4, it is made of 0.2mm thick CFRP with reference to the shape of the caudal fin of an eel.

[0058] The eel robotic fish of the present invention is composed of 5 connected tube-segment dielectric elastomer actuators 2, a head 1, a caudal peduncle 3 and a caudal fin 4, and the specific dimensions are shown in Table 2.

[0059] Table 2 Dimensions of eel robot fish

[0060] Body length (mm) Body height (mm) Weight(g) 273 35.3 26.83

[0061] like Figure 7-8As shown, a mark is set at the front end of the head of the robot fish, and a 4.5kV sinusoidal alternating current is applied to the left and right of the connected drive module with a phase difference of 180 degrees. The frequencies are: 0.1Hz, 0.3Hz, 0.5Hz, 1.0Hz, 1.2Hz, 1.5Hz, 2.0Hz, 3.0Hz, 4.0Hz, 5.0Hz, 6.0Hz, 7.0Hz; 8.0Hz, 9.0Hz, 10.0Hz. Comparing the propulsion speeds of each frequency, the highest propulsion speed at a frequency of 1.5Hz is 43.7mm / s. The highest propulsion speed of the prototype robot fish calculated by the body length ratio is 0.16BL / s.

[0062] like Figure 9-10 As shown, in order to compare the swimming shape of the prototype robotic fish with that of a living organism, the displacement of the head and each joint perpendicular to the direction of travel was measured using dynamic images taken from above with a camera. Fig.10 It can be seen that when the robot fish starts to drive, the waveform will be slightly disordered, but after 1 second, the waveform has almost no change, and it keeps swimming steadily. The data is offset by using the linear approximation of the least squares method to align the vibration center.

[0063] The present invention also includes a central pattern generator (CPG) control system. As a motion control mechanism, CPG has the following main features: (1) it can self-excite to generate rhythmic control signals; (2) it is a distributed control; and (3) it is based on a dynamic system parameter adjustment mechanism. The CPG control method incorporates the planning and control processes into a dynamic system, condenses the dynamic characteristics of the nervous system-body-environment system into the limited parameters of the dynamic system, and obtains the desired output characteristics by adjusting the parameters. It does not need to model the entire system, thus avoiding complex kinematics and inverse kinematics calculations.

[0064] Therefore, the present invention provides a dielectric eel-like robotic fish, which achieves low noise, high flexibility and efficient propulsion performance by adopting a lightweight tube-type dielectric elastomer driver and an optimized fluid mechanics design. The robotic fish not only overcomes the problems of high noise, bulky structure and poor environmental adaptability of traditional rigid robotic fish, but also its modular design is easy to maintain; at the same time, the introduction of the central pattern generator (CPG) control system further simplifies the control process and improves the response speed and accuracy, making it have significant advantages in various application scenarios such as marine biological ecological surveys and seabed exploration.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A dielectric elastomer-based eel-like robotic fish, comprising five connected tube-segment dielectric elastomer actuators, a head, a caudal peduncle and a caudal fin, characterized in that: The head is connected to one end of the tube-segment dielectric elastomer driver, the tail handle is connected to the other end of the tube-segment dielectric elastomer driver, and the tail fin is connected to the tail handle; the tube-segment dielectric elastomer driver consists of a circular frame, a central elastic plate, a dielectric elastomer and an electrode, the circular frame is divided into circular frame one and circular frame two, and the circular frame one and the circular frame two are male and female structures.

2. The eel-like robotic fish based on dielectric elastomer according to claim 1, characterized in that: The circular frame has a diameter of 30 mm and a thickness of 3 mm, and the pre-stretching ratios are 4 times in the axial direction and 3 times in the circumferential direction.

3. The eel-like robotic fish based on dielectric elastomer according to claim 1, characterized in that: The central elastic plate is used to connect the circular frame one and the circular frame two, and the dielectric elastomer is wound around the circular frame one and the circular frame two.

4. The eel-like robotic fish based on dielectric elastomer according to claim 3, characterized in that: The central elastic plate has a length of 30 mm, a width of 10 mm and a thickness of 0.2 mm.

5. The eel-like robotic fish based on dielectric elastomer according to claim 1, characterized in that: The electrode is made of carbon powder and is coated on the inner side of the dielectric elastomer.

6. The eel-like robotic fish based on dielectric elastomer according to claim 1, characterized in that: The circular frame is made of carbon fiber reinforced plastic (CFRP) material, and the central elastic plate is made of polyethylene terephthalate (PET) material.

7. The eel-like robotic fish based on dielectric elastomer according to claim 1, characterized in that: The head, the caudal peduncle and the caudal fin are designed as smooth structures. The caudal fin imitates the shape of the caudal fin of an eel and is made of 0.2 mm thick CFRP material.

8. The eel-like robotic fish based on dielectric elastomer according to claim 1, characterized in that: The dielectric elastomer actuator has an operating voltage of 4.5 kV sinusoidal alternating current, a frequency range of 0.1 Hz to 10.0 Hz, and an optimal driving frequency of 1.5 Hz.

9. The eel-like robotic fish based on dielectric elastomer according to claim 1, characterized in that: The eel robot fish has a total length of 273 mm, a height of 35.3 mm, and a total weight of 26.83 g.

10. The eel-like robotic fish based on dielectric elastomer according to claim 1, characterized in that: It also includes a central pattern generator CPG control system, which is used for self-excitation to generate rhythmic control signals, distributed control and dynamic system parameter adjustment mechanism.

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