Bionic fishtail structure and underwater bionic robot

Abstract

The invention relates to the technical field of bionic fishtail structures, and provides a bionic fishtail structure and an underwater bionic robot. The two ends of a fishbone structure are connected with a driving adapter and a tail fin structure correspondingly, the end, away from the fishbone structure, of the driving adapter is used for being connected with a driving device, and the fishbone structure is driven by the driving device to do reciprocating swing motion; the gradient variable stiffness structure covers the fishbone structure; the hyperelastic memory alloy wire penetrates through the fishbone structure, and the two ends of the hyperelastic memory alloy wire are connected with the driving adapter and the tail fin structure respectively. The driving adapter, the fishbone structure, the tail fin structure, the gradient variable stiffness structure and the hyperelastic memory alloy wire are matched with one another, elastic reset of the hyperelastic memory alloy wire can assist the driving device to enable the fishbone structure to passively swing, underwater stress changes are adapted, the simulation performance of the fishtail structure is improved, and the service life of the fishbone structure is prolonged. A fish body-tail fin propelling mode is simulated, the excellent flexible maneuvering performance is achieved, the noise level is lowered, and the concealment is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bionic robots, and more particularly, to a bionic fish tail structure and an underwater bionic robot. Background Art

[0002] With the continuous development of marine resources and the increasing attention paid to the marine environment, underwater robots are increasingly widely used in the fields of marine exploration, resource development, environmental monitoring, and military reconnaissance.

[0003] Existing underwater robots generally adopt traditional propeller propulsion and some conventional mechanical drive methods. Although these propulsion methods have simple structures, they have problems such as high noise, poor maneuverability, and high energy consumption, which limit their application effects in specific environments. Summary of the Invention

[0004] The present invention aims to solve at least one of the above technical problems.

[0005] To solve the above problems, the present invention provides a bionic fish tail structure and an underwater bionic robot.

[0006] In a first aspect, the present invention provides a bionic fish tail structure, including a drive adapter, a fishbone structure, a tail fin structure, a gradient variable stiffness structure, and a superelastic shape memory alloy wire; both ends of the fishbone structure are respectively connected to the drive adapter and the tail fin structure, and one end of the drive adapter away from the fishbone structure is used to be connected to a drive device, and the drive device drives the fishbone structure to perform a reciprocating swinging motion; the gradient variable stiffness structure is coated on the fishbone structure; the superelastic shape memory alloy wire penetrates through the fishbone structure, and both ends of the superelastic shape memory alloy wire are respectively connected to the drive adapter and the tail fin structure.

[0007] Optionally, the fishbone structure includes a plurality of main bone segments connected to each other, and any two adjacent main bone segments are respectively rotationally connected by a joint ball; each main bone segment and each joint ball are respectively provided with through holes, and the superelastic shape memory alloy wire penetrates through the corresponding through holes on each main bone segment and each joint ball.

[0008] Optionally, spherical grooves are respectively formed at both ends of each main bone segment, and the joint ball is rotationally connected between the spherical grooves of any two adjacent main bone segments.

[0009] Optionally, the fishbone structure further includes ribs, and two ribs are symmetrically arranged on each main bone segment.

[0010] Optionally, the gradient variable stiffness structure includes a gradient variable stiffness body and an outer skin. The gradient variable stiffness body covers the fishbone structure. A plurality of hexagonal honeycomb structures are spaced apart on the gradient variable stiffness body. The outer skin covers the gradient variable stiffness body.

[0011] Optionally, the outer skin forms a plurality of independent cavities with the plurality of hexagonal honeycomb structures, and air holes communicating the two cavities are formed between any two adjacent hexagonal honeycomb structures.

[0012] Optionally, the tail fin structure includes a tail fin body and a tail bone. One end of the tail bone is connected to the tail fin body, and the other end is connected to the end of the fishbone structure away from the drive adapter.

[0013] Optionally, the drive adapter includes a connecting rod and a connecting disk connected to each other. The connecting rod is used to connect to the drive device. The superelastic memory alloy wire is connected to the connecting disk, and the connecting disk abuts against the end of the gradient variable stiffness structure away from the tail fin structure.

[0014] Optionally, the gradient variable stiffness body and the tail fin body are made of a soft rubber material with a hardness of 30.

[0015] In a second aspect, the present invention provides an underwater bionic robot, including the bionic fish tail structure as described above.

[0016] The beneficial effects of the bionic fish tail structure and the underwater bionic robot of the present invention are as follows: A fish bone structure and a tail fin structure are connected, and a gradient variable stiffness structure is coated on the fish bone structure to form a bionic fish tail structure, simulating the shape of the tail of a fish swimming freely underwater, reducing the running resistance of the underwater robot in water. The driving adapter is used to connect with the driving device to drive the fish bone structure to make reciprocating swinging movements. During operation, the fish bone structure provides a basic swinging framework for the swinging of the fish tail, and the tail fin structure generates a certain propulsive force with the swinging movement, providing power for the forward movement of the bionic fish tail structure. The gradient variable stiffness structure is coated on the fish bone structure to simulate the flexibility of the tail of a real fish, improving the underwater maneuverability. While protecting the fish bone structure, it can also reduce the vibration and noise generated during the swinging of the fish bone structure, improving the concealment. A super-elastic memory alloy wire penetrates through the fish bone structure, and its two ends are respectively connected to the driving adapter and the tail fin structure, which can assist the driving device in precisely controlling the fish bone structure and the tail fin structure. The fish bone structure is driven to swing passively under the drive of the super-elastic memory alloy wire, better adapting to the underwater stress and offsetting a certain amount of underwater resistance for the swinging of the bionic fish tail structure, reducing the energy consumption of the driving device. For the bionic fish tail structure of the present invention, the driving adapter, the fish bone structure, the tail fin structure, the gradient variable stiffness structure, and the super-elastic memory alloy wire cooperate with each other. By the driving device and stress changes, it simulates the fish body-tail fin propulsion mode, enabling the underwater robot to quickly turn, accelerate, and decelerate in water, having excellent flexible maneuverability, good stability, high reliability, and strong adaptability. Compared with the propeller propulsion structure of traditional underwater robots, it has a bionic structure closer to the natural movement of fish, reducing the noise level and improving the concealment, while having a lower manufacturing cost and being easy to process and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of the bionic fish tail structure according to an embodiment of the present invention Figure 1 ;

[0018] Figure 2 is a schematic structural diagram of the fish bone structure and the tail fin structure according to an embodiment of the present invention;

[0019] Figure 3 is a schematic structural diagram of the fish bone structure according to an embodiment of the present invention;

[0020] Figure 4 is a schematic structural diagram of the gradient variable stiffness structure according to an embodiment of the present invention;

[0021] Figure 5 is a schematic structural diagram of the driving adapter according to an embodiment of the present invention;

[0022] Figure 6 is a schematic structural diagram of the tail bone according to an embodiment of the present invention;

[0023] Figure 7Schematic structural diagram of the caudal fin body according to an embodiment of the present invention.

[0024] Description of reference numerals:

[0025] 1 - Driving adapter; 11 - Adapter rod; 12 - Adapter disc;

[0026] 2 - Fishbone structure; 21 - Main bone segment; 211 - Spherical groove; 22 - Joint ball; 23 - Through hole; 24 - Rib;

[0027] 3 - Caudal fin structure; 31 - Caudal fin body; 32 - Caudal bone;

[0028] 4 - Gradient variable stiffness structure; 41 - Gradient variable stiffness body; 411 - Air hole. Detailed implementation manners

[0029] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following describes the specific embodiments of the present invention in detail with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments described herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.

[0030] The term "including" and its variants used herein are open-ended, that is, "including but not limited to"; the term "based on" is "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiment". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts such as "first" and "second" mentioned in the present invention are only used to distinguish different devices, modules, or units, and are not used to limit the order or interdependence relationship of the functions performed by these devices, modules, or units.

[0031] It should be noted that the modifications of "one" and "multiple" mentioned in the present invention are illustrative rather than restrictive. Those skilled in the art should understand that unless otherwise clearly specified in the context, it should be understood as "one or more".

[0032] As Figures 1 to 7 shown, a bionic fish tail structure provided by an embodiment of the present invention includes a driving adapter 1, a fishbone structure 2, a caudal fin structure 3, a gradient variable stiffness structure 4, and a superelastic memory alloy wire;

[0033] Both ends of the fishbone structure 2 are respectively connected to the driving adapter 1 and the caudal fin structure 3. One end of the driving adapter 1 away from the fishbone structure 2 is used to connect to a driving device, and the driving device drives the fishbone structure 2 to perform a reciprocating swinging motion; the gradient variable stiffness structure 4 is coated on the fishbone structure 2; the superelastic memory alloy wire penetrates through the fishbone structure 2, and both ends of the superelastic memory alloy wire are respectively connected to the driving adapter 1 and the caudal fin structure 3.

[0034] Specifically, the fishbone structure 2 is used to provide a movable framework. As Figure 2 shown, the fishbone structure 2 is based on a fishbone prototype, and its shape is the same as the fishbone shape at the fish tail. One end has a wider width, and its width gradually decreases along the length direction (i.e., from one end to the other end). And the main bone segments 21 of each section of the fishbone structure 2 are movably connected to perform a reciprocating swinging motion. One end of the driving adapter 1 is connected to the driving device. The driving device can be a steering gear or a motor with a crank-rocker structure, etc. The wider end of the fishbone structure 2 is connected to the other end of the driving adapter 1. When the driving device operates, the driving adapter 1 transfers the force generated by the driving device to the fishbone structure 2 to drive the fishbone structure 2 to perform a reciprocating swinging motion to imitate the fish tail motion during the fish's forward movement. The end of the fishbone structure 2 away from the driving adapter 1 is connected to the caudal fin structure 3. As Figure 1 , Figure 2 and Figure 7 shown, the caudal fin structure 3 is based on a fish tail fin prototype, and its shape is the same as the tail fin shape. And the caudal fin structure 3 is symmetrically distributed along the central axis. When the driving adapter 1 drives the fishbone structure 2 to perform a left-right reciprocating swinging motion through the driving device, it drives the caudal fin structure 3 to also perform a left-right swinging motion to provide propulsion and direction control for the bionic robot, thereby realizing steering and attitude adjustment.

[0035] It should be noted that the driving adapter 1 and the fishbone structure 2 are made of hard resin or other rigid materials with the same hardness and properties to ensure support and transmission.

[0036] As Figure 1 and Figure 4As shown, the gradient variable stiffness structure 4 is wrapped around the fishbone structure 2. Its horizontal cross-sectional shape matches that of the fishbone structure 2. Moreover, the gradient variable stiffness structure 4 is provided with structures of a preset shape (such as circular, rectangular, etc.), and the size gradually decreases from the end close to the driving device to the end close to the tail fin structure 3. As a result, the stiffness of the end of the gradient variable stiffness structure 4 close to the driving device is smaller, and the stiffness of the end of the gradient variable stiffness structure 4 close to the tail fin structure 3 is larger. Thus, it more realistically simulates the stiffness distribution of the fish tail muscle, enables the swing wave to naturally amplify when propagating from the driving end to the tail fin end, and is closer to the kinematic characteristics of biological swimming. When the driving device drives the fishbone structure 2 to swing reciprocally, the gradient variable stiffness structure 4 attached to the fishbone structure 2 is passively stressed. One side is stressed and compressed while the other side is stressed and stretched. The end of the gradient variable stiffness structure 4 close to the driving device has a smaller stiffness and can deform better, effectively absorbing the energy of the motor. The end of the gradient variable stiffness structure 4 close to the tail fin structure 3 has a larger stiffness, enhancing the thrust transfer efficiency and reducing energy loss. At the same time, it maintains morphological stability under fluid resistance and avoids thrust dispersion caused by excessive deformation. By simulating the fish body-tail fin propulsion mode through the driving device and stress changes, it can better adapt to different water flow and attitude adjustment requirements and has excellent underwater maneuverability.

[0037] In a preferred embodiment, the gradient variable stiffness structure 4 is made of soft rubber with a hardness of 30 to simulate the flexibility of the tail of a real fish, protect the internal fishbone structure, reduce damage caused by collisions or friction, and at the same time be able to absorb impact force, improve the stability and durability of the robot in a complex water environment, effectively increase the propulsion efficiency and service life of the bionic robot, adapt to different water flow conditions, improve adaptability, and the flexibility of the soft rubber can reduce the vibration and noise generated during swinging, increasing underwater environmental protection and concealment. In other embodiments, the gradient variable stiffness structure 4 can also be made of other flexible materials with the same hardness and properties, and the effects are the same as those of the soft rubber with a hardness of 30.

[0038] Specifically, the swing amplitude and frequency of the fishbone structure 2 and the tail fin structure 3 are controlled by the driving device, and since the underwater resistance will produce a certain resistance to the swing of the fishbone structure 2 and the tail fin structure 3, the starting device needs to apply a larger driving force, which results in larger losses and larger vibrations and noises. In order to more accurately control the swing amplitude and frequency of the fishbone structure 2 and the tail fin structure 3, and to reduce the operating force of the driving device, a superelastic memory alloy wire is arranged throughout the fishbone structure 2, and the two ends of the superelastic memory alloy wire are respectively fixedly connected to the driving adapter 1 and the tail fin structure 3. The superelastic memory alloy wire has superelasticity and can restore to its original state after a large deformation, and is suitable for the underwater fishtail swinging motion of the present application. For example, after the driving device drives the fishbone structure 2 and the tail fin structure 3 to swing to the left through the driving adapter 1, the superelastic memory alloy wire can quickly drive the fishbone structure 2 and the tail fin structure 3 to return to a horizontal position or assist the driving device in driving the fishbone structure 2 and the tail fin structure 3 to swing to the right through the driving adapter 1.

[0039] It should be noted that since the shape memory performance stability and fatigue resistance of memory titanium alloy are better than those of iron alloy, and the phase change temperature adjustability and corrosion resistance are better than those of copper alloy, and considering the cost and process maturity, the memory alloy wire is preferably made of room temperature superelastic nickel-titanium alloy to produce better elasticity and durability, better simulate the smooth movement of biological skeletal structure, and reduce maintenance costs.

[0040] In this embodiment, the fishbone structure 2 and the caudal fin structure 3 are connected, and the gradient variable stiffness structure 4 is coated on the fishbone structure 2 to form a bionic fish tail structure, simulating the shape of the tail of a fish moving freely underwater and reducing the running resistance of the underwater robot in water. The driving adapter 1 is used to connect with the driving device to drive the fishbone structure 2 to make a reciprocating swinging motion. During operation, the fishbone structure 2 provides a basic swinging framework for the fish tail swing. The caudal fin structure 3 generates a certain propulsive force with the swinging motion, providing power for the forward movement of the bionic fish tail structure. The gradient variable stiffness structure 4 is coated on the fishbone structure 2 to simulate the flexibility of the tail of a real fish, improve the underwater maneuverability, protect the fishbone structure 2 while also reducing the vibration and noise generated during the swinging of the fishbone structure 2, and improve the concealment. The super-elastic shape memory alloy wire penetrates through the fishbone structure, and its two ends are respectively connected to the driving adapter 1 and the caudal fin structure 3, which can assist the driving device in precisely controlling the fishbone structure 2 and the caudal fin structure 3. The fishbone structure 2 is driven to swing passively under the drive of the super-elastic shape memory alloy wire, more adapting to the underwater stress while offsetting a certain amount of underwater resistance for the swing of the bionic fish tail structure, and reducing the energy consumption of the driving device during operation. For the bionic fish tail structure of the present invention, the driving adapter 1, the fishbone structure 2, the caudal fin structure 3, the gradient variable stiffness structure 4, and the super-elastic shape memory alloy wire cooperate with each other, and simulate the fish body-caudal fin propulsion mode through the driving device and stress changes, realizing rapid turning, acceleration, and deceleration of the underwater robot in water. It has excellent flexible maneuverability, good stability, high reliability, and strong adaptability. Compared with the propeller propulsion structure of traditional underwater robots, it has a bionic structure closer to the natural movement of fish, reduces the noise level and improves the concealment, and at the same time has a lower manufacturing cost, is easy to process and maintain.

[0041] Optionally, the fishbone structure 2 includes a plurality of main bone segments 21 connected to each other, and any two adjacent main bone segments 21 are respectively rotatably connected by a joint ball 22; through holes 23 are respectively formed in each main bone segment 21 and each joint ball 22, and the super-elastic shape memory alloy wire penetrates through the corresponding through holes 23 on each main bone segment 21 and each joint ball 22.

[0042] Specifically, the fishbone structure 2 needs to ensure flexible swinging. The sequentially connected main bone segments 21 and joint balls 22 can ensure the flexibility of the fishbone structure 2 during the reciprocating swinging motion. As Figure 2 shown, the main bone segment 21 is approximately cylindrical, and the joint balls 22 are respectively rotatably connected to the two circular end faces of the main bone segment 21. The joint balls 22 can rotate freely between two adjacent main bone segments 21. When the fishbone structure 2 is stressed and moves, the joint balls 22 and the main bone segments 21 can rotate relative to each other to realize the reciprocating swinging motion of the fishbone structure 2, improving the movement flexibility of the bionic fish tail structure. In a preferred embodiment, as Figure 2As shown, the main bone segments 21 can be 10 in number, and the corresponding joint balls 22 are 9 in number.

[0043] As Figure 3 shown, through holes 23 are correspondingly formed on each main bone segment 21 and each joint ball 22. The super-elastic memory alloy wires can pass through the through holes 23 on each main bone segment 21 and each joint ball 22 to connect the fishbone structure in series, so as to realize the control of the swing angle and swing frequency of the fishbone structure 2 by the driving device. It should be noted that at least one through hole 23 is formed on each main bone segment 21 and each joint ball 22. In the present embodiment as Figure 3 shown, 4 through holes 23 are formed on each main bone segment 21 and each joint ball 22 in a centrosymmetric manner, and four super-elastic memory alloy wires are correspondingly provided to increase the connection tightness.

[0044] Optionally, spherical grooves 211 are respectively formed at both ends of each main bone segment 21, and the joint ball 22 is rotatably connected between the spherical grooves 211 of any two adjacent main bone segments 21.

[0045] Specifically, the spherical groove 211 can cooperate with the joint ball 22, which is more conducive to the flexible rotation of the joint ball 22 and the main bone segment 21 when stressed. Spherical grooves 211 are formed on the circular end faces of each main bone segment 21 in the shape of a quasi-cylindrical body. The joint ball 22 can be rotatably connected to the main bone segment 21 through the spherical groove 211, increasing the swing flexibility of the fishbone structure.

[0046] It should be noted that the shape of the spherical groove 211 can match the joint ball 22, or can be slightly larger than the size of the joint ball 22 to form a clearance fit with the joint ball 22. For example, a certain gap needs to be left between the groove surface of the spherical groove 211 and the end face of the joint ball 22, and the gap length is 1 / 20 of the diameter of the joint ball 22, so as to reduce the friction between the joint ball 22 and the spherical groove 211 on the main bone segment 21 and ensure the swing flexibility of the fishbone structure 2.

[0047] It should be noted that the main bone segments 21 at the starting position and the ending position need to be connected to the driving adapter 1 and the tail fin structure 3. In order to ensure the connection tightness, the end faces of the corresponding main bone segments 21 facing the driving adapter 1 and the tail fin structure 3 may not be provided with spherical grooves 211 and remain in a flat structure.

[0048] Optionally, the fishbone structure 2 further includes ribs 24, and two ribs 24 are symmetrically arranged on each main bone segment 21.

[0049] Specifically, since the gradient variable stiffness structure 4 has a certain flexibility, it may cause the distortion of the fish tail shape during the swinging process, resulting in problems in the operation of the bionic fish tail robot. By providing the ribs 24, a supporting effect can be provided for the gradient variable stiffness structure 4. As Figure 3As shown, each main bone segment 21 corresponds to two ribs 24. The two ribs 24 are symmetrically arranged on the circumferential outer surface of the main bone segment 21 in the up and down direction, that is, perpendicular to the swinging direction. As Figure 1 shown, when the gradient variable stiffness structure 4 wraps the fish bone structure 2, the ribs 24 are inserted between the gradient variable stiffness structures 4 to prevent the gradient variable stiffness structure 4 from falling off or deforming, and ensure the stability of the rope-laying fish tail structure robot.

[0050] It should be noted that the thickness of the rib 24 is 1 / 10 of the maximum diameter of the main bone segment 21. In this case, the bionic fish bone structure operates in the optimal state.

[0051] Optionally, the gradient variable stiffness structure 4 includes a gradient variable stiffness body 41 and an outer skin. The gradient variable stiffness body 41 wraps the fish bone structure 2. A plurality of hexagonal honeycomb structures are spaced apart on the gradient variable stiffness body 41. The outer skin wraps the gradient variable stiffness body 41.

[0052] Specifically, the gradient variable stiffness body 41 is used to wrap the fish bone structure 2 to form a bionic fish tail structure, simulating the shape of the tail of a fish swimming freely underwater, and can deform with the reciprocating swing movement of the fish bone structure 2 to adapt to the change of underwater environmental stress, and then simulate the fish body-fin propulsion mode. The outer skin wraps the outside of the gradient variable stiffness body 41 and is a waterproof material to ensure that the use environment of each structure inside it always remains dry and increase the service life. A plurality of hexagonal honeycomb structures are spaced apart on the gradient variable stiffness body 41. The wall widths of the plurality of hexagonal honeycomb structures are the same, and from the end close to the driving adapter 1 to the end far from the driving adapter 1, the diameter of the circumcircle of the hexagon gradually increases to achieve the gradient variable stiffness of the structure. It should be noted that compared with shapes such as circular hole structures, the hexagonal structure has the advantages of high stability, uniform stress distribution, and making full use of material strength to achieve lightweight design, which is more conducive to underwater operation.

[0053] Exemplarily, as Figure 4 shown, the gradient variable stiffness body 41 includes multiple rows of hexagonal honeycomb structures. Each row of hexagonal honeycomb structures includes a plurality of hexagonal honeycomb structures spaced apart along the extension direction of the fish bone structure 2. Each hexagonal honeycomb structure can be a groove or hole that penetrates the gradient variable stiffness body 41 up and down. For example, taking the gradient variable stiffness body 41 including three rows of hexagonal honeycomb structures as an example, the middle row of hexagonal honeycomb structures can be a hole structure, and the two outer rows of hexagonal honeycomb structures can be groove structures.

[0054] Optionally, the outer skin makes the plurality of hexagonal honeycomb structures form a plurality of independent cavities, and air holes 411 communicating the two cavities are opened between any two adjacent hexagonal honeycomb structures.

[0055] Specifically, after the outer skin wraps the gradient variable stiffness body 41, multiple hexagonal honeycomb structures are formed inside the gradient variable stiffness body 41 to form multiple independent cavities. When the fishbone structure 2 is subjected to reciprocating swinging motion, the gradient variable stiffness body 41 deforms under force, and the cavities also deform. The deformation inside the cavities causes the internal air pressure to change, increasing the movement resistance, affecting the coordination of the tail fin swing, and consuming energy at the same time, resulting in an increase in the energy consumption of the robot and a decrease in the serial number ability. In addition, the compression and expansion of air may also generate noise, affecting the underwater concealment of the bionic robot. Therefore, air holes 411 connecting the two cavities are provided between any two adjacent hexagonal honeycomb structures to ensure the gas flow exchange between the cavities, so that the gradient variable stiffness body 41 deforms well and uniformly when subjected to force, and the bionic fish tail structure swings more coordinately.

[0056] Optionally, the tail fin structure 3 includes a tail fin body 31 and a tail bone 32. One end of the tail bone 32 is connected to the tail fin body 31, and the other end is connected to the end of the fishbone structure 2 away from the drive adapter 1.

[0057] Specifically, as Figure 7 shown, the tail fin body 31 is symmetrically distributed along the central axis and is made of a soft rubber material with a hardness of 30, which helps the tail fin body 31 to swing more naturally with the swinging motion of the fishbone structure 2, realize more complex motion modes, improve the propulsion efficiency and maneuverability, and reduce the vibration and noise during operation at the same time.

[0058] As Figure 6 shown, the tail bone 32 is a stress transition area from the fishbone structure 2 to the tail fin body 31, which is arranged between the tail fin body 31 and the fishbone structure 2. Its shape imitates the mutated part at the end of the tuna fishbone. The end face of the tail bone 32 connected to the fishbone structure 2 is a circle matching the circular end face of the main bone segment 21. The end face of the tail bone 32 connected to the tail fin body 31 is a cross-shaped circular shape with a smooth curve transition that is proportional to the major and minor axes of the circular end face of the tail fin body 31 facing the tail bone. The setting of the tail bone 32 is beneficial to the uniform distribution of stress, driving the follow-up movement of the flexible tail fin body 31, and finally realizing the swing of the bionic fish tail structure corresponding to the fish body envelope. Through holes 23 can be provided on the end face of the tail bone 32 facing the fishbone structure 2, corresponding to the through holes 23 on the main bone segment 21 and the joint ball 22. The superelastic memory alloy wire can be glued at the through holes 23 on the tail bone 32, or the superelastic memory alloy wire can also be directly glued on the end face of the tail bone 32 facing the fishbone structure 2.

[0059] Optionally, the driving adapter 1 includes an adapter rod 11 and an adapter plate 12 which are connected to each other. The adapter rod 11 is used to connect to the driving device, the super-elastic memory alloy wire is connected to the adapter plate 12, and the adapter plate 12 abuts against one end of the gradient variable stiffness structure 4 away from the tail fin structure 3.

[0060] Specifically, as Figure 5 shown, the adapter rod 11 is used to connect to the driving device, and the adapter plate 12 is used to connect to the fishbone structure 2 to transmit the power of the driving device to the fishbone structure 2. The adapter rod 11 is inserted into the adapter plate 12. A connection groove and / or connection hole adapted to the swing amplitude of the fishbone-like structure are provided at one end of the adapter rod 11 away from the adapter plate 12 to facilitate connection to the driving device. To ensure connection stability, the connection groove is at least twice the length of the matching driving device, and the angle of the tangent line formed by the circle with the center of the connection hole being the driving point of the driving device and the radius being the length of the matching driving part should be 1 / 2 of the maximum swing angle of the selected bionic fish body tail.

[0061] It should be noted that through holes 23 can be provided on the end face of the adapter plate 12 facing the fishbone structure 2, corresponding to the through holes 23 on the main bone segment 21 and the joint ball 22. The super-elastic memory alloy wire can be adhesively bonded at the through holes 23 on the adapter plate 12, or the super-elastic memory alloy wire can also be directly adhesively bonded on the end face of the adapter plate 12 facing the fishbone structure 2.

[0062] An underwater bionic robot provided by an embodiment of the present invention includes the bionic fish tail structure as described above.

[0063] The beneficial effects of the underwater bionic robot in this embodiment compared with the prior art are the same as those of the above bionic fish tail structure and will not be elaborated here.

[0064] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A bionic fishtail structure, characterized in that: The invention comprises a driving adapter (1), a fishbone structure (2), a tail fin structure (3), a gradient variable stiffness structure (4) and a superelastic memory alloy wire; the two ends of the fishbone structure (2) are respectively connected to the driving adapter (1) and the tail fin structure (3); the end of the driving adapter (1) away from the fishbone structure (2) is used to be connected to a driving device, and the driving device drives the fishbone structure (2) to perform reciprocating swinging motion; the gradient variable stiffness structure (4) is coated on the fishbone structure (2); the superelastic memory alloy wire runs through the fishbone structure (2), and the two ends of the superelastic memory alloy wire are respectively connected to the driving adapter (1) and the tail fin structure (3).

2. The bionic fishtail structure according to claim 1, characterized in that: The fishbone structure (2) comprises a plurality of main bone segments (21) connected to each other, and any two adjacent main bone segments (21) are rotatably connected via joint balls (22); each main bone segment (21) and each joint ball (22) are respectively provided with a through hole (23), and the superelastic memory alloy wire passes through the corresponding through hole (23) on each main bone segment (21) and each joint ball (22).

3. The bionic fishtail structure according to claim 2, characterized in that: Both ends of each main bone segment (21) are respectively provided with a spherical groove (211), and the joint ball (22) is rotatably connected between the spherical grooves (211) of any two adjacent main bone segments (21).

4. The bionic fishtail structure according to claim 2, characterized in that: The fishbone structure (2) further comprises ribs (24), and two of the ribs (24) are symmetrically arranged on each of the main bone segments (21).

5. The bionic fishtail structure according to claim 1, characterized in that: The gradient variable stiffness structure (4) comprises a gradient variable stiffness body (41) and an outer skin, wherein the gradient variable stiffness body (41) is coated on the fishbone structure (2), a plurality of hexagonal honeycomb structures are arranged at intervals on the gradient variable stiffness body (41), and the outer skin is coated on the gradient variable stiffness body (41).

6. The bionic fishtail structure according to claim 5, characterized in that: The outer skin enables the plurality of hexagonal honeycomb structures to form a plurality of independent cavities, and an air hole (411) connecting the two cavities is provided between any two adjacent hexagonal honeycomb structures.

7. The bionic fishtail structure according to claim 1, characterized in that: The tail fin structure (3) comprises a tail fin body (31) and a coccyx (32), one end of the coccyx (32) being connected to the tail fin body (31), and the other end being connected to an end of the fishbone structure (2) away from the drive adapter (1).

8. The bionic fishtail structure according to claim 1, characterized in that: The drive adapter (1) comprises an adapter rod (11) and an adapter plate (12) which are connected to each other, the adapter rod (11) being used to be connected to the drive device, the superelastic memory alloy wire being connected to the adapter plate (12), and the adapter plate (12) being in contact with an end of the gradient variable stiffness structure (4) away from the tail fin structure (3).

9. The bionic fishtail structure according to claims 5 and 7, characterized in that: The gradient variable stiffness body (41) and the tail fin body (31) are made of a soft rubber material with a hardness of 30.

10. An underwater bionic robot, characterized in that: It comprises the bionic fishtail structure as described in any one of claims 1 to 9.

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