Multi-stage self-adaptive rigidity adjusting system for line-driven bionic fish

Abstract

The invention provides a multistage self-adaptive rigidity adjusting system for a line-driven bionic fish, and belongs to the technical field of ocean robots, the multistage self-adaptive rigidity adjusting system comprises a fish body, a power mechanism of a fishtail propelling device is arranged in the fish body, the power mechanism comprises a steering engine, and a winch is controlled by the steering engine to rotate so as to drive a stay wire and a fishtail to swing, so that a propelling function is realized; the multi-stage variable rigidity adjusting device is mounted in the fish body, is sequentially connected with each section of the fish tail through a mooring rope and a spring, and is used for adjusting the initial tension of each section of the fish tail so as to realize the rigidity change of different sections; the microcontroller is installed in the fish body and used for controlling the working states of the fishtail propelling device and the multi-stage variable rigidity adjusting device and dynamically adjusting the swing amplitude and frequency of the fishtail and rigidity distribution of all the sections. Segmented flexible response of all the segments of the fishtail is achieved under the action of cable traction and springs, independent rigidity adjustment can be achieved, and therefore the motion adaptability and the propelling efficiency of the fishtail in the multi-working-condition environment are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of marine robots, and particularly relates to a multi-stage adaptive stiffness adjustment system for a cable-driven bionic fish. Background Art

[0002] As an important branch in the field of marine robots, bionic fish have received extensive attention in recent years in applications such as marine exploration, underwater inspection, and environmental monitoring due to their excellent fluid adaptability, low-noise propulsion characteristics, and high maneuverability. Most existing bionic fish propulsion systems adopt methods such as cable drive, servo actuator drive, or flexible drive to achieve the left and right swing of the fish tail, simulating the natural swimming process. However, most existing cable-driven bionic fish only simulate fish movement in terms of the propulsion method, with a single and fixed stiffness of the fish tail structure, making it difficult to flexibly change according to the swimming state, resulting in low propulsion efficiency and limited control performance, and it is difficult to adapt to complex underwater environmental changes.

[0003] In nature, the fish tail shows a gradually changing stiffness characteristic of being rigid near the body, moderate in the middle section, and compliant at the end. This multi-stage stiffness distribution enables it to have good propulsion efficiency during high-speed swimming and excellent flexibility during low-speed or turning. Limited by traditional mechanical structures and control methods, there is currently a lack of a structural design and control strategy that can achieve zonal adjustment of the fish tail stiffness and dynamically optimize the stiffness distribution according to the swimming state.

[0004] In addition, the existing methods for adjusting the swing amplitude and frequency of the fish tail are relatively single, lacking the ability to dynamically adjust the tail stiffness, and unable to achieve the coordinated optimization of propulsion performance and energy consumption efficiency. Therefore, there is an urgent need for a cable-driven bionic fish system with multi-stage adaptive stiffness adjustment ability to more realistically restore the movement mechanism of fish and improve the propulsion efficiency and control ability of bionic fish under various working conditions. Summary of the Invention

[0005] The purpose of the present invention is to provide a multi-stage adaptive stiffness adjustment system for a cable-driven bionic fish, realizing the dynamic adjustment of the stiffness of each segment of the fish tail, thereby optimizing the propulsion performance and control ability of the bionic fish.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A multi-stage adaptive stiffness adjustment system for a cable-driven bionic fish, comprising: a fish body, a cable-driven fish tail propulsion device, a multi-stage variable stiffness adjustment device, and a microcontroller;

[0008] The power mechanism of the fish tail propulsion device is arranged inside the fish body. The power mechanism includes a servo motor, and the winch is controlled by the servo motor to rotate to drive the cable, driving the fish tail to swing, thereby realizing the propulsion function;

[0009] The multi-stage variable stiffness adjustment device is installed inside the fish body and is connected to each segment of the fish tail in sequence through a cable and a spring, and is used to adjust the initial tension of each segment of the fish tail to achieve the stiffness change of different segments;

[0010] The microcontroller is installed inside the fish body and is used to control the working states of the fish tail propulsion device and the multi-stage variable stiffness adjustment device, and dynamically adjust the swing amplitude, frequency and stiffness distribution of each segment of the fish tail.

[0011] Further, the multi-stage variable stiffness adjustment device includes a stiffness adjustment servo, a multi-layer winch, a set of fish tail end cables, a set of winch end cables, a set of stiffness adjustment springs, a cable guide frame, a cable guide shaft and a mounting plate frame assembly;

[0012] The cable guide frame is located between the multi-layer winch and the fish tail;

[0013] One end of the fish tail end cable is connected to the fish tail, the other end of the fish tail end cable is connected to the winch end cable through the stiffness adjustment spring, and the winch end cable is connected to the multi-layer winch;

[0014] The stiffness adjustment servo drives the multi-layer winch to rotate synchronously, thereby driving the winch end cable to move, stretching or releasing the stiffness adjustment spring to change its initial tension and adjust the swing stiffness of the connected fish tail segment.

[0015] Further, the multi-stage variable stiffness adjustment device has 7 fish tail end cables, which are respectively connected to the fish tail segment structures of the fish tail. The left and right ends of the first 3 fish tail segment structures of the fish tail are respectively connected to 2 fish tail end cables, and the last fish tail segment structure of the fish tail is connected to 1 fish tail end cable. The fish tail end cables provide restoring forces for each segment of the fish tail through springs, and cooperate to provide the swing stiffness of the overall fish tail.

[0016] Further, the 7 fish tail end cables are guided by the cable guide frame and are respectively connected to 4 of the stiffness adjustment springs. Each of the stiffness adjustment springs independently adjusts the stiffness of one segment of the fish tail; the 4 stiffness adjustment springs are connected to the multi-layer winch through 4 cables connecting the winch ends through the cable guide shaft. The multi-layer winch has 4 layers of structures, and each layer rotates synchronously to achieve the stiffness adjustment of multiple fish tail segments.

[0017] Further, the cable guide frame includes a main body fixing frame, and 3 groups of guide short shafts and 1 guide long shaft are installed on the main body fixing frame; the 3 groups of guide short shafts are respectively located at the upper rear, lower rear and upper front of the main body fixing frame, and each group of guide short shafts includes 3 guide short shafts.

[0018] Further, three guiding short shafts located above and below the rear of the main body fixing frame are respectively butted with three tail fin end cables at the upper part and three tail fin end cables at the lower part, playing a guiding role, so as to realize the convergence and grouping of the first six cables, forming three strands of cables. The three strands of cables are guided by a guiding long shaft and are respectively connected to three stiffness adjustment springs.

[0019] Further, the seventh tail fin end cable in the middle is connected to the end segment of the tail fin, guided by a guiding long shaft, and connected to the fourth stiffness adjustment spring;

[0020] The guiding long shaft is used to guide the four strands of cables to be finally connected to a multi-layer winch, realizing the unified arrangement of the cable paths.

[0021] Further, the tail fin includes four tail fin segment structures, and the tail fin segment structures are connected by a central rotating shaft;

[0022] Under the combined action of the traction force of the tail fin end cable and the restoring force of the stiffness adjustment spring, the first three tail fin segment structures can realize the tail wagging movement in the left and right directions to simulate the tail fluctuation mode in the real fish swimming process;

[0023] The seventh tail fin end cable is fixed at the connection point of the fourth tail fin segment structure and sequentially passes through the first to third tail fin segment structures, and is used to adjust the stiffness of the overall tail fin swing.

[0024] Further, the multi-layer winch adopts a modular winch, and the length of the rotating arm of the winch can be flexibly adjusted by replacing drums with different diameters.

[0025] Further, it further includes a power cable. One end of the main cable of the power cable is fixed at the connection point of the fourth tail fin segment structure, and the other end is connected to the winch, and is used to provide the driving force required for the overall tail fin swing.

[0026] The beneficial effects of the present invention are as follows:

[0027] Through a multi-stage variable stiffness adjustment system, the present invention enables different segments of the tail fin to have a differential stiffness distribution, simulating the characteristics of near-body rigidity, moderate mid-section elasticity, and compliant end of real fish, improving the propulsion efficiency and maneuverability of the bionic fish; a microcontroller is used to realize the dynamic adjustment of the tail fin stiffness, enabling the bionic fish to adaptively optimize the stiffness distribution according to the swimming state, and enhancing the support ability during high-speed straight propulsion and the flexibility during low-speed turning.

[0028] By integrating seven tail fin end cables into four strands and respectively connecting them to four independent springs, the present invention realizes the independent control of the stiffness of each segment of the tail fin, with a compact structure and high transmission efficiency.

[0029] The multi-layer winch structure of the present invention is compactly designed, capable of synchronously controlling the spring tension adjustment of multiple segments, simplifying the system layout, and improving the adjustment accuracy. The cable guide frame is reasonably arranged. Through the combined design of a short shaft and a long shaft, the cable path is effectively optimized, reducing the risks of friction and entanglement, and enhancing the system reliability.

[0030] The multi-stage adaptive stiffness adjustment method proposed by the present invention can significantly improve the motion performance of the bionic fish in complex underwater environments, and expand the application prospects of the bionic fish in fields such as ocean exploration and environmental monitoring.

[0031] The multi-stage variable stiffness adjustment device of the present invention is connected to each segment of the fish tail through springs respectively. By adjusting the initial tension of the springs, the fish tail shows different swing stiffnesses in different segments, thereby realizing the multi-stage stiffness distribution of the fish tail with a rigid near-body part, a moderately elastic middle part, and a compliant end part, simulating the muscle characteristics of real fish. The stiffness of the fish tail can be dynamically optimized regionally according to the swimming frequency and load state to improve the energy utilization efficiency. For example, when swimming straight at high speed, the near-body stiffness is enhanced to provide effective support, and when swimming at low speed or turning, the tail end is softened to enhance flexibility. Brief Description of the Drawings

[0032] Attached Figure 1 is a schematic structural diagram of the present invention.

[0033] Attached Figure 2 is a schematic internal structural diagram of the present invention.

[0034] Attached Figure 3 is a schematic structural diagram of the multi-stage variable stiffness adjustment device of the present invention.

[0035] Attached Figure 4 is a schematic structural diagram of the guide frame of the present invention.

[0036] Attached Figure 5 is a schematic structural diagram of the fish tail of the present invention.

[0037] Attached Figure 6 is Attached Figure 2 's front view.

[0038] In the drawings: 1. Fish body; 2. Fish tail propulsion device; 3. Multi-stage variable stiffness adjustment device; 4. Microcontroller; 5. Power cable; 6. Winch; 201. Fish tail; 301. Stiffness adjustment servo; 302. Multi-layer winch; 303. Fish tail end cable; 304. Winch end cable; 305. Stiffness adjustment spring; 306. Cable guide frame; 3061. Guide short shaft; 3062. Guide long shaft; 3063. Main body fixing frame; 307. Cable guide shaft; 308. Mounting plate frame assembly. Detailed Embodiments

[0039] The present invention will be further described below with reference to the drawings.

[0040] The present invention provides a multi - level adaptive stiffness adjustment system for a cable - driven bionic fish. As shown in the appendix Figure 1-2 it includes: a fish body 1, a cable - driven fish - tail propulsion device 2, a multi - level variable stiffness adjustment device 3, and a micro - controller 4;

[0041] The power mechanism of the fish - tail propulsion device 2 is arranged inside the fish body 1. The power mechanism includes a servo - motor, which controls the winch to rotate to drive the cable, and drives the fish - tail to swing, so as to achieve the propulsion function;

[0042] The multi - level variable stiffness adjustment device 3 is installed inside the fish body 1, and the segments of the fish - tail 201 are sequentially connected by cables and springs, which is used to adjust the initial tension of each segment of the fish - tail to achieve the stiffness change of different segments;

[0043] The micro - controller 4 is installed inside the fish body 1, which is used to control the working states of the fish - tail propulsion device 2 and the multi - level variable stiffness adjustment device 3, and dynamically adjust the swing amplitude, frequency and the stiffness distribution of each segment of the fish - tail 201.

[0044] This embodiment further includes a power cable 5. One end of the main cable of the power cable is fixed at the connection point of the 4th segment of the fish - tail 201, and the other end is connected to the winch 6, which is used to provide the driving force required for the overall swing of the fish - tail. The power cable is fixed at the connection point of the 4th segment and sequentially passes through the fish - tail segment structures of the 1st to 3rd segments, which is used to provide the driving force required for the overall swing of the fish - tail.

[0045] As shown in the appendix Figure 3 The multi - level variable stiffness adjustment device 3 includes a stiffness - adjustment servo - motor 301, a multi - layer winch 302, a group of fish - tail - end cables 303, a group of winch - end cables 304, a group of stiffness - adjustment springs 305, a cable guide frame 306, a cable guide shaft 307, and a mounting - plate frame assembly 308;

[0046] The cable guide frame 306 is located between the multi - layer winch 302 and the fish - tail 201;

[0047] One end of the fish - tail - end cable 303 is connected to the fish - tail 201, the other end of the fish - tail - end cable 303 is connected to the winch - end cable 304 through the stiffness - adjustment spring 305, and the winch - end cable 304 is connected to the multi - layer winch 302;

[0048] The stiffness - adjustment servo - motor 301 drives the multi - layer winch 302 to rotate synchronously, thereby driving the winch - end cable 304 to move, stretching or releasing the stiffness - adjustment spring 305, so as to change its initial tension and adjust the swing stiffness of the connected fish - tail segment.

[0049] The multi-layer winch 302 adopts a modular winch. By replacing the drums with different diameters, the length of the turning force arm of the winch can be flexibly adjusted, the cable is wound in layers, and the tension of each section of the fish tail is controlled separately.

[0050] In this embodiment, the multi-stage variable stiffness adjustment device 3 has 7 fish tail end cables 303, which are respectively connected to the fish tail section structures of the fish tail 201. The upper and lower ends of the first 3 fish tail section structures of the fish tail 201 are respectively connected to 2 fish tail end cables 303, and the last fish tail section structure of the fish tail 201 is connected to 1 fish tail end cable 303. The fish tail end cables 303 provide a restoring force for each section of the fish tail through springs, and cooperate to provide the swing stiffness of the overall fish tail.

[0051] The 7 fish tail end cables 303 are guided by a cable guide frame 306 and are respectively connected to 4 of the stiffness adjustment springs 305. Each of the stiffness adjustment springs 305 independently adjusts the stiffness of one section of the fish tail; the 4 stiffness adjustment springs 305 are connected to the multi-layer winch 302 through 4 cables 304 connected to the winch end through a cable guide shaft 307. The multi-layer winch has 4 layers of structures, and each layer rotates synchronously to realize the stiffness adjustment of multiple fish tail sections.

[0052] The cable guide shaft 307 further ensures a smooth cable path and prevents entanglement.

[0053] The mounting plate frame assembly 308 is used to fix the above mechanism and maintain the overall stability.

[0054] As shown in the Figure 4 accompanying drawings, the cable guide frame 306 is used to arrange and guide the cable path, and it consists of: a main body fixing frame 3063, which is used to fix the guide short shaft and long shaft and support the guiding structure. 3 groups of guide short shafts 3061 and 1 guide long shaft 3062 are installed on the main body fixing frame 3063; the 3 groups of guide short shafts 3061 are respectively located at the upper rear, lower rear and upper front of the main body fixing frame 3063, and each group of guide short shafts 3061 includes 3 guide short shafts 3061.

[0055] The 3 guide short shafts 3061 located at the upper rear and lower rear of the main body fixing frame 3063 are respectively butted against the 3 upper fish tail end cables 303 and the 3 lower fish tail end cables 303, playing a guiding role, so as to realize the convergence and grouping of the first 6 cables, forming 3 strands of cables. The 3 strands of cables are guided by the guide long shaft 3062 and are respectively connected to 3 stiffness adjustment springs 305.

[0056] The 7th fish tail end cable 303 in the middle is connected to the end section of the fish tail, and is guided by the guide long shaft 3062 and connected to the 4th stiffness adjustment spring 305.

[0057] The guiding long shaft 3062 is arranged at the end of the guiding frame and is used to guide 4 cables to be finally connected to the multi-layer winch 302, so as to realize the unified arrangement of the cable paths, avoid cable crossing and abrasion, and improve the system reliability.

[0058] Among them, 9 guiding short shafts 3061 are responsible for merging and sorting the 7 connecting cable ends 303 of each segment of the fish tail into 4 cables, and each cable is connected to one segment of the fish tail, so as to realize the independent control of the swing stiffness of a single segment of the fish tail by a single stiffness adjustment spring 305 subsequently. The guiding short shafts are arranged in a specific path to ensure that the cables are smooth and evenly stressed during the merging process.

[0059] Furthermore, 9 guiding short shafts are used to converge and group the 7 cables 303 connecting each segment of the fish tail into 4 cables. The 9 short shafts are distributed as follows: 3 in the upper rear, 3 in the lower rear, and 3 in the upper front. The 3 short shafts in the upper rear and the 3 short shafts in the lower rear are respectively docked with the upper 3 and the lower 3 of the cable ends at the fish tail end, playing a guiding role, so as to realize the effective combing and grouping of the first 6 cables.

[0060] In the order from top to bottom, the numbers of the rear short shafts are successively Rear 1, Rear 2, Rear 3 (upper) and Rear 4, Rear 5, Rear 6 (lower), and the numbers of the front short shafts are Front 1, Front 2, Front 3. The specific connection method is as follows:

[0061] The cable passing through Rear 1 and Rear 6 is connected to the first segment of the fish tail, and after being guided by Front 1, it is connected to the same spring;

[0062] The cable passing through Rear 2 and Rear 5 is connected to the second segment of the fish tail, and after being guided by Front 2, it is merged and connected to another spring;

[0063] The cable passing through Rear 3 and Rear 4 is connected to the third segment of the fish tail, and after being guided and merged by Front 3, it is finally connected to the corresponding spring.

[0064] The seventh cable in the middle is directly connected to the end segment of the fish tail, without being guided by a short shaft, but is guided by the only long shaft and finally connected to a dedicated spring.

[0065] Through the above grouping and guiding mechanism, each cable independently controls one segment of the fish tail structure, so that each segment of the fish tail can be independently adjusted in stiffness by the corresponding spring, thereby realizing the multi-segment adaptive flexible control of the fish tail.

[0066] As shown in the Figure 5 attachment, the fish tail 201 includes 4 fish tail segment structures, and the fish tail segment structures are connected by a central rotating shaft;

[0067] Under the combined action of the traction force of the cable 303 at the fish tail end and the restoring force of the stiffness adjustment spring 305 in the first three sections of the fish tail structure, the fish tail can achieve a swinging motion in the left - right direction to simulate the tail undulation mode during the swimming of real fish.

[0068] The seventh cable 303 at the fish tail end is fixed at the connection point of the fourth section of the fish tail structure and passes through the first to the third sections of the fish tail structure in sequence, for adjusting the stiffness of the overall fish tail swing.

[0069] Further, the fish tail sequentially includes the first to the fourth sections from front to back.

[0070] Under the combined action of the traction force of the power cable 5 and the restoring force of the stiffness adjustment spring, the fish tail structure can achieve a swinging motion in the left - right direction to simulate the tail undulation mode during the swimming of real fish.

[0071] Further, the fish tail structure is provided with 7 stiffness cable connection points (labeled as "stiffness connection point *7"), corresponding to 7 stiffness adjustment cables 303 respectively; the cables are converged and grouped via the cable guide frame 306 and guided to be connected to the stiffness adjustment springs corresponding to each section. The connection relationship is as follows:

[0072] Connection point 1 and connection point 6: are respectively arranged on the upper and lower sides of the first section for adjusting the stiffness of the first section.

[0073] Connection point 2 and connection point 5: are respectively arranged on the upper and lower sides of the second section for adjusting the stiffness of the second section.

[0074] Connection point 3 and connection point 4: are respectively arranged on the upper and lower sides of the third section for adjusting the stiffness of the third section.

[0075] Connection point 7: is set at the position of the fish tail central axis and is connected to the stiffness adjustment spring of the fourth section.

[0076] When the present invention is installed, the guide short shaft 3061 and the guide long shaft 3062 are respectively installed on the main body fixing frame 3063. All the cables 303 first pass through the guide short shaft 3061 to form a stranded cable, and then are smoothly led out through the guide long shaft 3062 and connected to the multi - layer winch 302. The cables are further straightened and guided at the cable guide shaft 307, and finally the multi - layer winch 302 is driven by the stiffness adjustment servo 301 to rotate synchronously, realizing the dynamic adjustment of the stiffness of each section of the fish tail.

[0077] Through the above structure, each section of the fish tail of the present invention can achieve segmented flexible response under the traction of the cable and the action of the spring, and can respectively achieve independent stiffness adjustment, thereby improving the motion adaptability and propulsion efficiency of the fish tail in multi - working - condition environments.

[0078] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and variations can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A multi-level adaptive stiffness adjustment system for a cable-driven bionic fish, characterized in that, Comprising: A fish body (1), a cable-driven fish tail propulsion device (2), a multi-stage variable stiffness adjustment device (3), and a microcontroller (4); The power mechanism of the fish tail propulsion device (2) is arranged inside the fish body (1). The power mechanism includes a servo motor, which controls the winch to rotate to drive the cable, driving the fish tail to swing, thereby realizing the propulsion function; The multi-stage variable stiffness adjustment device (3) is installed inside the fish body (1), and each section of the fish tail (201) is sequentially connected through a cable and a spring, which is used to adjust the initial tension of each section of the fish tail to realize the stiffness change of different sections; The microcontroller (4) is installed inside the fish body (1), which is used to control the working states of the fish tail propulsion device (2) and the multi-stage variable stiffness adjustment device (3), and dynamically adjust the swing amplitude, frequency of the fish tail (201), and the stiffness distribution of each section.

2. The multi-level adaptive stiffness adjustment system for a cable-driven bionic fish according to claim 1, characterized in that, The multi-stage variable stiffness adjustment device (3) includes a stiffness adjustment servo motor (301), a multi-layer winch (302), a set of fish tail end cables (303), a set of winch end cables (304), a set of stiffness adjustment springs (305), a cable guide frame (306), a cable guide shaft (307), and a mounting plate frame assembly (308); The cable guide frame (306) is located between the multi-layer winch (302) and the fish tail (201); One end of the fish tail end cable (303) is connected to the fish tail (201), and the other end of the fish tail end cable (303) is connected to the winch end cable (304) through the stiffness adjustment spring (305), and the winch end cable (304) is connected to the multi-layer winch (302); The stiffness adjustment servo motor (301) drives the multi-layer winch (302) to rotate synchronously, thereby driving the winch end cable (304) to move, stretching or releasing the stiffness adjustment spring (305), so as to change its initial tension and adjust the swing stiffness of the connected fish tail section.

3. The multi-level adaptive stiffness adjustment system for a cable-driven bionic fish according to claim 1 or 2, characterized in that, The multi-stage variable stiffness adjustment device (3) has 7 fish tail end cables (303), which are respectively connected to the fish tail section structures of the fish tail (201). The left and right ends of the first 3 fish tail section structures of the fish tail (201) are respectively connected to 2 fish tail end cables (303), and the last fish tail section structure of the fish tail (201) is connected to 1 fish tail end cable (303). The fish tail end cables (303) provide a restoring force for each section of the fish tail through springs, and work together to provide the swing stiffness of the overall fish tail.

4. The multi-level adaptive stiffness adjustment system for a wire-driven bionic fish according to claim 3, wherein, The 7 fish tail end cables (303) are guided by the cable guide frame (306) and are respectively connected to 4 of the stiffness adjustment springs (305). Each of the stiffness adjustment springs (305) independently adjusts the stiffness of one section of the fish tail; the 4 stiffness adjustment springs (305) are connected to the multi-layer winch (302) through 4 cables connecting the winch ends through the cable guide shaft (307). The multi-layer winch has 4 layers of structures, and each layer rotates synchronously to realize the stiffness adjustment of multiple fish tail sections.

5. The multi-level adaptive stiffness adjustment system for the wire-driven bionic fish according to claim 4, wherein, The cable guiding frame (306) includes a main body fixing frame (3063), and three sets of guiding short shafts (3061) and one guiding long shaft (3062) are installed on the main body fixing frame (3063); the three sets of guiding short shafts (3061) are respectively located at the upper rear, lower rear and upper front of the main body fixing frame (3063), and each set of guiding short shafts (3061) includes three guiding short shafts (3061).

6. The multi-stage adaptive stiffness adjustment system for a cable-driven bionic fish according to claim 5, wherein The three guiding short shafts (3061) located at the upper rear and lower rear of the main body fixing frame (3063) are respectively docked with the three fish-tail end cables (303) at the upper part and the three fish-tail end cables (303) at the lower part, playing a guiding role, so as to realize the convergence and grouping of the first six cables, forming three strands of cables, and the three strands of cables are guided by the guiding long shaft (3062) and respectively connected to three stiffness adjustment springs (305).

7. The multi-level adaptive stiffness adjustment system for a cable-driven bionic fish according to claim 6, wherein The seventh fish-tail end cable (303) in the middle is connected to the end segment of the fish tail, guided by the guiding long shaft (3062), and connected to the fourth stiffness adjustment spring (305); The guiding long shaft is used to guide four strands of cables and finally connect them to the multi-layer winch (302) to realize the unified arrangement of the cable path.

8. The multi-stage adaptive stiffness adjustment system for a cable-driven bionic fish according to claim 2 or 7, characterized in that, The fish tail (201) includes four fish-tail segment structures, and the fish-tail segment structures are connected by a central rotating shaft; Under the combined action of the traction force of the fish-tail end cable (303) and the restoring force of the stiffness adjustment spring (305), the first three fish-tail segment structures can realize the tail-swinging motion in the left-right direction to simulate the tail fluctuation mode in the real fish swimming process; The seventh fish-tail end cable (303) is fixed at the connection point of the fourth fish-tail segment structure and sequentially passes through the first to third fish-tail segment structures, and is used to adjust the stiffness of the overall swing of the fish tail.

9. The multi-level adaptive stiffness adjustment system for the wire-driven bionic fish according to claim 2, characterized in that The multi-layer winch (302) adopts a modular winch, and the length of the rotating arm of the winch can be flexibly adjusted by replacing drums with different diameters.

10. The multi-level adaptive stiffness adjustment system for a cable-driven bionic fish according to claim 8, wherein, It further includes a power cable (5), one end of the main cable of the power cable is fixed at the connection point of the fourth fish-tail segment structure, and the other end is connected to the winch (6), and is used to provide the driving force required for the overall swing of the fish tail.

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