CN113697075B - Controllable robot based on photosensitive intelligent composite material - Google Patents

Abstract

The invention discloses a controllable robot based on a photosensitive intelligent composite material, which comprises a bionic fish main body and an illuminating device arranged on the bionic fish main body; the bionic fish body comprises a trunk, a pair of main fins with the same structure, a pair of auxiliary fins with the same structure and a tail fin connected with the rear end of the trunk, wherein the main fins and the auxiliary fins are symmetrically arranged on two sides of the trunk from front to back; the main fin and the auxiliary fin are of plate-type structures and are in airfoil shapes; the lighting device is used for providing lighting for the two main fins and the two auxiliary fins; the material used for the trunk is non-hydrophilic material; the main fin, the auxiliary fin and the tail fin are made of asymmetric double-layer composite materials consisting of hydrogel photosensitive materials and thermal expansion materials, and the hydrogel photosensitive materials face the light source of the lighting device. This controllable robot based on photosensitive intelligent combined material is higher to the illumination responsivity, can rely on natural light or artificial light source, realizes directional drive and the turn at the surface of water to can regard as the actuating mechanism of environmental monitoring under water, load devices such as camera and realize environmental monitoring under water.

Description

Controllable robot based on photosensitive smart composite material

technical field

The invention belongs to the field of robots and relates to a controllable robot driven by a photosensitive intelligent material.

Background technique

Bionic robotic fish is a type of robot that imitates fish in structure and movement, and is mainly used to monitor the underwater environment. In recent years, the research results of new bionic robot fish have been emerging, and based on different driving methods, the tail fins are driven to swing according to predetermined rules, so as to swim in the water. These drive methods include motor drive, hydraulic or pneumatic drive, shape memory alloy (SMA) drive, dielectric elastomer (DEs) drive and ion polymer metal composite (IPMC) drive, etc.

However, there are certain problems in the driving methods given above. For example, the bionic robot fish driven by the motor generally adopts a rigid structure with multi-joint transmission, which is complicated in structure, and the noise and vibration are relatively large; It is difficult to realize unrestrained swimming; new materials such as SMA have defects such as small deformation and insufficient driving force, it is difficult to accurately simulate fish movement, and there are problems such as insufficient driving force and driving speed.

Contents of the invention

The purpose of the present invention is to provide a controllable robot driven by photosensitive materials, which has a deep-sea short-nosed lionfish structure, for the problems of complex driving structure, difficulty in simulating fish shape and motion, and insufficient driving force in traditional bionic robotic fish. It can work in natural still water environment.

In order to achieve the above object, the present invention adopts the following technical solutions to achieve.

The inventive idea of the present invention is that, based on the bionic structure of fish, the asymmetrical bimorph electric driver is produced by combining the hydrogel photosensitive material with photosensitive properties and the thermal expansion material with a large thermal expansion coefficient, which produces a large The macroscopic deformation provides greater driving speed.

The controllable robot based on photosensitive intelligent composite materials provided by the present invention includes a bionic fish main body and an illuminating device arranged on the bionic fish main body; A pair of main fins with the same structure, a pair of auxiliary fins with the same structure, and a tail fin connected to the rear end of the trunk; the main fins and the auxiliary fins are plate-shaped structures, which are airfoils; The main fin and two auxiliary fins provide illumination; the material used for the torso is a non-hydrophilic material; the material used for the main fin, auxiliary fins, and tail fins is an asymmetric double-layered hydrogel photosensitive material and thermal expansion material. layer composite material, and the hydrogel photosensitive material faces the light source of the lighting device.

For the above-mentioned controllable robot based on photosensitive intelligent composite materials, the main body shape of the bionic fish is preferably a bionic structure of a deep-sea shortnose lionfish. As shown in Figure 3, the deep-sea short-nosed lionfish has the following two characteristics: (1) thin bones, easy to bend, flexible muscle tissue, and fine fiber tissue; Pressure balance, strong resistance to pressure. Based on the above analysis, in the present invention, the designed bionic fish body also has a fish-like body shape. Wherein, the torso is made of non-hydrophilic material, and the non-hydrophilic material has a certain strength and is not easily deformed, and ABS plastic, PLA plastic, plexiglass, etc. can be used. The main fin, auxiliary fin and tail fin are made of soft asymmetric double-layer composite material, which is mainly used as the driving part of the entire controllable robot. Here, the asymmetric double-layer composite material is composed of hydrogel photosensitive material and thermal expansion material. of. The hydrogel photosensitive material is preferably an IPTS-modified Mxene film (Ying Hu et al, Self-Lovomotive Soft Actuator Bsaed on Asymmetric Microstructural Ti ₃ C ₂ T _x MXeneFilmDriven by Natural Sunlight Fluctuation, ACS Nano 2021, 15, 5294-5306) In the present invention, the Mxene thin film characteristic of IPTS modification is that the interlayer spacing of the top is larger, and hydrophilicity is better, and the bottom interlayer spacing is smaller, and hydrophilicity is poor, and when in water, due to the adsorption of water molecule The effect is not equal, the expansion rate of the top is higher than that of the bottom, and the overall structure will produce a downward bending force on a macroscopic level. The thermal expansion material has a large thermal expansion coefficient, preferably PE film, PE film is a commercially used polymer material with a large thermal expansion coefficient (about 500×10 ^-6 /°C), and the IPTS modified Mxene film is attached to the on PE film. In water, due to its own hydrophilicity, the IPTS-modified Mxene film absorbs water and bends downward. When irradiated by a light source with a certain intensity, the light energy absorbed by the IPTS-modified Mxene film is converted into heat energy. The IPTS-modified MXene film The water molecules adsorbed on the top and bottom of the top lose rapidly, and the shrinkage of the top is greater than that of the bottom. At the same time, the heat energy is further transferred to the PE film, and the PE film undergoes thermal expansion, which maximizes the bending deformation of the overall structure and makes the asymmetric double layer composite recovery. In this way, the tiny solid structure is bonded to the "muscle" at the bottom of the main body of the bionic robot, and light energy can be converted into mechanical energy for movement through light-to-heat conversion. When the bionic robot is irradiated by a controllable light source, the muscles will relax and contract and deform, which will drive the main fin, accessory fin and tail fin to beat and drive the bionic deep-sea short-nosed lionfish robot.

In the above-mentioned controllable robot based on photosensitive intelligent composite materials, the torso mainly plays two roles: one is to support the whole bionic robot; the other is to connect the main fin, auxiliary fin and tail fin. The section of the torso along the length direction is an inverted trapezoidal structure, and a fish head in a triangular structure extends from the front end.

In the above-mentioned controllable robot based on photosensitive smart composite materials, the main function of the main fin is to provide the main driving force through bending and returning motion. The main function of the auxiliary fin includes two aspects: one is to provide a certain driving force through bending and restoring; the other is to turn the robot through bending and restoring.

The upper and lower end faces of the main fin are parallel to the end face of the trunk, and it is composed of three sides connected together along the circumferential direction, one of which is attached to the side of the trunk, and the two adjacent sides are opposite arc surfaces; define the main fin The side of the fin near the head of the fish is the upper arc, and the opposite side is the lower arc. In this way, the main fin deviates at a certain angle relative to the central axis of the torso, so that the main fin is generally bent rearward. Further, the two ends of the upper arc surface of the main fin are located on the extension line of one side of the fish head, and the angle of the extension line away from the central axis of the trunk (that is, the angle at which the main fin deviates from the central axis of the trunk) is 40°-50°.

The bending mechanism of the auxiliary fin is the same as that of the main fin when it moves, so the structure of the auxiliary fin is similar to that of the main fin. The upper and lower end faces of the auxiliary fin are parallel to the end face of the trunk. The side is fitted with the side of the trunk, and the two adjacent sides are opposite arc surfaces; the side that defines the accessory fin close to the fish head is the upper arc surface, and the other opposite side is the lower arc surface. Further, the two ends of the arc surface of the accessory fin are located on a parallel line parallel to one side of the fish head, and the angle of the parallel line away from the central axis of the trunk (that is, the angle at which the accessory fin deviates from the central axis of the trunk) is 40° to 50°. °.

In this way, the main fin can provide better power for driving the robot. When the angle of the main fin deviating from the central axis of the trunk is less than 40° (for example, 30°), the backward component force of the main fin is small; The fin and caudal fin will be closer together, and when the auxiliary fin deviates from a larger angle, if the volume of the auxiliary fin is designed to be small, it may not be enough to provide the power to realize the turning of the whole bionic fish robot on the water surface.

For the above-mentioned controllable robot based on photosensitive intelligent composite materials, the main functions of the tail fin include two aspects: on the one hand, it is used to adjust the balance of the left and right sides of the bionic fish robot; on the other hand, it is used to provide a certain driving force through bending and restoration. The plane shape of the main body of the caudal fin is similar to the torso, and its section along the length direction is an inverted trapezoidal structure, and the area of the front end surface is not larger than the area of the rear end surface of the torso. As the controllable robot moves, the tail fin curves toward the bottom of the biomimetic fish (i.e., downward).

For the above-mentioned controllable robot based on photosensitive intelligent composite materials, in order to make the controllable robot have a good driving effect in water, the main body size of the bionic fish needs to meet certain requirements. In the present invention, the length of the trunk, the length of the main fin (the length of the line connecting the two points on the arc surface of the main fin), the length of the secondary fin (the length of the line connecting the two points on the surface of the secondary fin) and the length ratio of the tail fin are (3～ 5): (3~5): 1:1. The curvature of the arc surfaces on both sides of the main fin and the auxiliary fin is (1/7*10 ^-2 ~1/8*10 ^-2 )m ^-1 . Especially when the controllable robot is applied (in natural still water or environment without power source), the thickness of the torso, main fin, auxiliary fin and caudal fin is the same or different, and is 4-8mm. The thickness of the heat-expandable material (such as PE film) in the double-layer material is 3.8-7.4mm, and the thickness of the hydrogel photosensitive material (such as IPTS-modified Mxene film) is 0.2-0.6mm.

In the above-mentioned controllable robot based on photosensitive intelligent composite materials, the lighting device includes a first light source assembly and a second light source assembly, the first light source assembly is used to illuminate the two main fins, and the second light source assembly is used to illuminate the two auxiliary fins; In this way, separate lighting control for the two main fins and the two auxiliary fins is realized. Each light source assembly includes a bracket fixed on the trunk, and two light sources extending from the end of the bracket respectively face the main fins or auxiliary fins on both sides of the trunk. Each bracket is provided with a controller for controlling the two light sources respectively.

Compared with the prior art, the controllable robot based on the photosensitive intelligent composite material provided by the present invention has the following outstanding advantages and beneficial technical effects:

1. The controllable robot provided by the present invention is equipped with a bionic fish main body, and the main fins, auxiliary fins and tail fins of the bionic fish main body are all drivers composed of hydrogel photosensitive materials and thermal expansion materials, which have high responsiveness to light. It can rely on natural light or artificial light source to realize directional driving and turning on the water surface, so it can be used as a driving mechanism for underwater environment monitoring, equipped with cameras and other devices to realize underwater environment monitoring.

2. The material used for the main fin, auxiliary fin and tail fin of the controllable robot bionic fish main body provided by the present invention includes an IPTS modified Mxene film, the top hydrophilicity is better, and the bottom hydrophilicity is poor, so that the upper and lower end surfaces The adsorption effect is not equal, the expansion rate of the top is higher than that of the bottom, and the overall structure produces obvious shape deformation on the macroscopic level, which in turn provides a greater driving speed in the process of light restoration.

3. The controllable robot provided by the present invention has low requirements on the environment due to its high photometric response, and has good stability. It does not need a high-power drive device and can be used normally in a weak light source environment.

4. The controllable robot provided by the present invention adopts the deep sea shortnose lionfish structure, so it can be used in natural still water and without power source environment.

Description of drawings

Figure 1 is a schematic diagram of the structure of a controllable robot based on photosensitive smart composite materials;

In the figure, 1-bionic fish main body, 11-trunk, 12-main fin, 13-secondary fin, 14-tail fin, 2-lighting device, 21-first light source component, 22-second light source component, 211, 221- Bracket, 212, 222 - light source.

Fig. 2 is a schematic diagram of the main structure of the controllable robot bionic fish.

Figure 3 is a schematic diagram illustrating the functions of each part of the deep-sea shortnose lionfish.

Fig. 4 is a schematic diagram of the structure and function of each part of the main body of the controllable robot bionic fish.

Fig. 5 is a schematic diagram of the material composition of each part of the main body of the controllable robot bionic fish.

Fig. 6 is a schematic diagram of the structure of an asymmetric double-layer composite material.

Fig. 7 is a schematic diagram of the driving principle of the main body of the controllable robot bionic fish.

Figure 8 is a schematic diagram of the state of the controllable robot bionic fish in different environments (viewed from the front of the bionic fish); where (a) is a schematic diagram of the state of the bionic fish under initial conditions; (b) is the bionic fish when the water absorption reaches saturation Schematic diagram of the main body state; (c) Schematic diagram of the restored state of the bionic fish in state (b) under light conditions.

Detailed ways

The embodiments of the present invention will be given below in conjunction with the accompanying drawings, and the technical solutions of the present invention will be further clearly and completely described through the embodiments. Apparently, the embodiments described are only some of the embodiments of the present invention, but not all of them. Based on the content of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts fall within the protection scope of the present invention.

Example

The controllable robot based on photosensitive intelligent composite material provided in this embodiment, as shown in FIG. 1 , includes a bionic fish main body 1 and an illumination device 2 arranged on the bionic fish main body. The main body 1 of the bionic fish adopts the bionic structure of the deep-sea short-nosed lionfish, which includes a trunk 11, a pair of main fins 12 with the same structure and a pair of auxiliary fins 13 with the same structure that are symmetrically arranged on both sides of the trunk 11 from front to back, and The caudal fin 14 that is connected with the trunk rear end. The lighting device 2 is used to provide lighting for the two main fins and the two auxiliary fins.

As shown in FIG. 1 , the section of the torso 11 along the length direction is an inverted trapezoidal structure, and a triangular fish head extends from the front end thereof. The plane shape of the tail fin 14 is similar to the trunk, and its section along the length direction is an inverted trapezoidal structure, and its front end surface area is not greater than the trunk rear end surface area. Both the main fin and the auxiliary fin are plate-shaped structures, and the structures are similar, and both are airfoil-shaped. The upper and lower end faces of the main fin 12 are parallel to the end face of the trunk, and it is composed of three sides connected together in the circumferential direction, one of which is attached to the side of the trunk, and the two adjacent sides are opposite arc surfaces; defining the main fin The side near the fish head is the upper arc, and the opposite side is the lower arc. The two ends of the upper arc surface of the main fin are located on the side extension line of the fish head, and the angle θ ₁ of the delay line from the central axis of the trunk is 45° (as shown in Figure 2). The upper and lower end faces of the auxiliary fin 13 are parallel to the end face of the trunk, and it is composed of three sides connected together along the circumferential direction, one of which is attached to the side of the trunk, and the two adjacent sides are opposite arc surfaces; defining the auxiliary fin The side near the fish head is the upper arc, and the opposite side is the lower arc. The two ends of the upper arc surface of the accessory fin are located on a parallel line parallel to one side of the fish head, and the angle θ ₂ of this parallel line departing from the central axis of the trunk is 45° (as shown in Figure 2).

As shown in Figure 4, the main functions of each part of the main body of the bionic fish are as follows:

(1) The torso mainly plays two roles: one is to support the whole bionic robot; the other is to connect the main fin, auxiliary fin and tail fin;

(2) The main function of the main fin is to provide the main driving force through bending and return motion;

(3) The main function of the auxiliary fin includes two aspects: one is to provide a certain driving force through bending and restoration; the other is to turn the robot through the bending and restoration.

(4) The main functions of the caudal fin include two aspects: one is used to adjust the balance of the left and right sides of the bionic fish robot; the other is used to provide a certain driving force through bending and restoration.

In this embodiment, the angle at which the main fin/auxiliary fin deviates from the central axis of the torso is 45°, which can provide a larger backward component force for the main body of the bionic fish.

As shown in Figure 5, the material composition of each part of the main body of the bionic fish in this embodiment is as follows:

(1) The material used for the torso is ABS plastic; the torso can be 3D printed using ABS plastic with a density of 1.1g/cm ³ to form a honeycomb structure with a thickness of about 6mm, which is to facilitate its floating on the water. The 3D printing parameters are: the thickness of a single layer is 0.1-0.3mm; the filling density is 20-30%; the printing speed is 50mm/s-60mm/s; the temperature of the printing nozzle is 230°C; the temperature of the hot bed is set to 70°C.

(2) The material used for the main fin, auxiliary fin and tail fin is an asymmetric double-layer composite material composed of a bottom-up PE film and an IPTS modified Mxene film (as shown in Figure 6), where the Mxene film refers to The Ti ₃ C ₂ T _x film is Ti 3 C 2 T x ; the thickness of the PE film is 4 mm, and the thickness of the IPTS modified Mxene film is 0.2 mm.

In this embodiment, the body length of the bionic fish is about 8.0 cm, the length of the body (ie the height of the inverted trapezoidal section) is about 5.0 cm, and the length of the caudal fin (ie the height of the inverted trapezoidal section) is about 2.5 cm. The length of the main fin is about 8.0cm, and the length of the auxiliary fin is about 2.5cm.

As shown in FIG. 1 , the lighting device 2 includes a first light source assembly 21 and a second light source assembly 22 . The first light source assembly 21 is used to illuminate the two main fins. The second light source assembly 22 illuminates the two auxiliary fins. Each light source assembly includes a bracket (211, 221) fixed on the torso, and two light sources (212, 222) extend from the ends of the bracket to respectively face the main fins or auxiliary fins on both sides of the torso. A controller is arranged in each bracket for controlling two light sources respectively. The controller can also communicate with the terminal server through the wireless communication module, and the terminal server sends an operation command to the controller, and the controller activates the corresponding light source according to the received operation command.

As shown in Figure 7 and Figure 8, the driving principle of the controllable robot based on the photosensitive intelligent composite material provided by this embodiment is:

(1) In the initial state, the main body of the robotic bionic fish is shown in Figure 8(a).

(2) When in water, the IPTS-modified Mxene film on the upper layer of the main fin and tail fin absorbs water and swells, and bends slowly downward (as shown in Figure 8(b)); at the same time, the IPTS-modified Mxene film on the upper layer of the auxiliary fin absorbs water and swells, Bend down slowly. This is because the IPTS-modified MXene film placed on the upper part is a hydrogel material, which has good hydrophilicity and contains a large number of hydrophilic functional groups, which can absorb water molecules through hydrogen bonds between surface groups and water molecules. , and the interaction is reversible, so once the bionic robot comes into contact with water, it will swell and absorb a large amount of water molecules at a corresponding speed. Compared with , the top has larger interlayer spacing and better hydrophilicity, so the top of the IPTS-modified MXene film can absorb more water molecules, resulting in greater swelling compared to the bottom. The main fin and auxiliary fin of the bionic fish body will slowly bend and deform at a corresponding speed to the water surface, and the tail fin will also slowly bend and deform to the water surface at a corresponding speed.

(3) Under the irradiation of natural light (sunlight) or light sources located above the main fins/auxiliary fins on both sides, the irradiated main fins/auxiliary fins restore their shape (as shown in Figure 8(c)), the main fins, auxiliary fins and tail fins There will be a backward propulsive resultant force on the water. Correspondingly, the water will give the bionic fish body a forward resultant force of the same size. This resultant force can push the bionic fish body to move forward at a corresponding speed; at the same time, adjust the irradiation The brightness change of the unilateral auxiliary fin light source can also provide the driving force for the main body of the bionic fish to turn. This is due to the fact that IPTS-modified MXene films exhibit high light absorption and excellent internal photothermal conversion capabilities (efficiency close to 100%) in a wide wavelength range (400–780 nm), when given a certain intensity of light source (natural light or artificial light source) When irradiated, the water molecules adsorbed on the top and bottom of the IPTS-modified MXene film lost rapidly, resulting in a decrease in the interlayer spacing, which caused the shrinkage deformation of the film to undergo recovery properties. Due to the asymmetry of the interlayer spacing, the shrinkage of the top The shrinkage greater than the bottom causes the entire film to undergo restorative bending deformation, and the bending direction is towards the top; at the same time, the heat energy is further transferred to the PE film, and the PE film thermally expands to maximize the bending deformation of the overall structure; at this time, the recovery Compared with the previous water absorption, the speed of bending deformation is obviously faster than that of the previous water absorption. Therefore, the main fin, auxiliary fin and tail fin of the bionic fish body will produce a backward propulsion force on the water. Correspondingly, the water There will be a resultant force of the same size forward for the main body of the bionic fish, and this resultant force will push the main body of the bionic fish to move forward rapidly at a corresponding speed.

(4) When the intensity of natural light received by the main fin/auxiliary fin changes or the artificial light source is turned off, the main fin and the auxiliary fin will absorb water and swell again, and bend slowly downward. This is because the MXene film modified by IPTS reabsorbs the surrounding water molecules and returns to its original shape. Compared with the process of dehydration under light, the speed of this process is relatively slow, and the impact on the displacement of the main body of the bionic fish can basically be ignored. Excluding.

Overall, the bionic deep-sea shortnose lionfish controllable robot will move quickly in a certain direction in the water like a lionfish under the control of natural or artificial light.

Those skilled in the art will appreciate that the embodiments described here are to help readers understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical revelations disclosed in the present invention without departing from the essence of the present invention, and these modifications and combinations are still within the protection scope of the present invention.

Claims (6)

1. A controllable robot based on photosensitive intelligent composite materials is characterized by comprising a bionic fish body (1) and a lighting device (2) arranged on the bionic fish body; the above-mentionedThe bionic fish body (1) comprises a trunk (11), a pair of main fins (12) with the same structure and a pair of auxiliary fins (13) with the same structure, which are symmetrically arranged on two sides of the trunk (11) from front to back in sequence, and a tail fin (14) connected with the rear end of the trunk; the main fin and the auxiliary fin are of plate-type structures and are in airfoil shapes; the upper end face and the lower end face of the auxiliary fin (13) are parallel to the end face of the trunk, the auxiliary fin is formed by three side faces which are connected together along the circumferential direction, one side face is attached to the side face of the trunk, two adjacent side faces are opposite cambered surfaces, two end points of the upper cambered surface of the auxiliary fin are positioned on a parallel line parallel to one side of the fish head, and the angle of the parallel line deviating from the central axis of the trunk is 40-50 degrees; the material used for the trunk is a non-hydrophilic material; the material used by the main fin, the auxiliary fin and the tail fin is an asymmetric double-layer composite material consisting of hydrogel photosensitive material and thermal expansion material, the hydrogel photosensitive material faces to a light source of the lighting device, wherein the hydrogel photosensitive material is an IPTS (isopropyl-tert-butyl-phenyl) modified Mxene film, and the Mxene film refers to Ti (titanium dioxide) film₃C₂T_xThe film, the thermal expansion material is PE film; the thickness of the IPTS modified Mxene film is 0.2mm, and the thickness of the PE film is 4mm; the illumination device (2) comprises a first light source assembly (21) for illuminating the two main fins and a second light source assembly (22) for illuminating the two sub-fins; the first light source assembly (21) comprises a bracket (211) fixed on the trunk, and two light sources (212) facing the main fins on the two sides of the trunk respectively extend from the tail end of the bracket; the second light source assembly (22) comprises a support (221) fixed on the trunk, and two light sources (222) respectively facing the auxiliary fins on the two sides of the trunk extend out of the tail end of the support; a controller for respectively controlling the two light sources is arranged in each bracket.

2. The controllable robot based on photosensitive intelligent composite material according to claim 1, wherein the trunk (11) has an inverted trapezoidal cross section along the length direction, and a fish head with a triangular structure extends from the front end surface.

3. The controllable robot based on photosensitive intelligent composite material according to claim 1 or 2, characterized in that the upper and lower end surfaces of the main fin (12) are parallel to the trunk end surface and are formed by three side surfaces which are connected together along the circumferential direction, wherein one side surface is attached to the trunk side surface, and two adjacent side surfaces are opposite cambered surfaces.

4. The controllable robot based on photosensitive intelligent composite material of claim 3, wherein two end points of the upper arc surface of the main fin are located on an extension line of one side of the fish head, and the angle of the extension line deviating from the central axis of the trunk is 40-50 degrees.

5. The controllable robot based on photosensitive intelligent composite material according to claim 1 or 2, characterized in that the cross section of the tail fin (14) along the length direction is in an inverted trapezoidal structure, and the area of the front end surface is not larger than that of the rear end surface of the trunk.

6. The controllable robot based on photosensitive smart composite of claim 5, wherein the ratio of the trunk length, the main fin length, the auxiliary fin length and the tail fin length is (3-5): (3-5): 1:1.

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