Fin-paddle composite multi-motion-mode bionic robotic fish

Abstract

The invention discloses a fin-paddle composite multi-motion-mode bionic robotic fish, and relates to the technical field of bionic fish structures. The problems that an existing bionic robotic fish is poor in maneuverability and cannot adapt to complex underwater tasks due to the single motion mode are solved. The fish comprises a streamline fish body composed of a fish head, a fish body and a fish tail. A tail swing propulsion system and a pair of multi-mode pectoral fin assemblies are integrated. The tail system adopts a driving motor to drive a cylindrical cam, rotary motion is converted into reciprocating swing of a fishtail through a transmission mechanism, and efficient main propulsive force is provided. According to the multi-mode pectoral fin assembly, the propeller unit is integrated on the pectoral fin body with the adjustable pitch angle, and fusion of pectoral fin gliding and propeller maneuvering is achieved. Through cooperative control of the electric control system, flexible switching of cruising, gliding, maneuvering and composite motion modes of cruising, gliding, maneuvering and the composite motion modes is achieved, and the comprehensive maneuverability, environmental adaptability and task execution capacity of the bionic robotic fish are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of biomimetic fish structure technology, specifically to a multi-motion biomimetic robotic fish with a composite fin and propeller. Background Technology

[0002] With the ocean's strategic importance constantly increasing and the demand for underwater operations growing, underwater robotics has become a key area of ​​global technological competition, demonstrating significant value in areas such as marine resource exploration, intelligence gathering, and underwater search and rescue. Bionic robotic fish are underwater fish-like mobility systems that propel themselves forward by mimicking the swimming movements of real fish. They offer advantages such as higher efficiency, lower noise, and more flexible movement, providing a superior solution for complex underwater tasks.

[0003] Currently, various biomimetic robotic fish with body and / or caudal fin (BCF) propulsion modes have been developed, but their maneuverability still lags significantly behind that of real fish. Real fish can flexibly change their swimming direction and rise and fall, achieving efficient swimming in complex environments through the coordinated action of their muscles and organs. Bionic robotic fish, limited by their mechanical structure and single actuation mechanism, cannot perform these movements as effectively as real fish. Therefore, it is necessary to add multiple movement modes to biomimetic fish to compensate for their poor maneuverability. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that existing bionic robotic fish have poor maneuverability and cannot adapt to complex underwater tasks due to their single movement mode, and to provide a bionic robotic fish with multiple movement modes of fin-propeller combination.

[0005] The technical solution of this invention is:

[0006] A biomimetic robotic fish with a multi-motion mode combining fins and propellers includes a streamlined fish body structure. The fish body structure comprises a head 2, a body 24, and a tail 20 connected in sequence. A skin 3 is attached to the outer side of the fish body structure, and a tail fin 5 is connected to the end of the tail 20. It also includes:

[0007] The tail-swing propulsion system includes a drive motor 25 disposed within the fish body 24, a reducer 26 connected to the output end of the drive motor 25, a cylindrical cam 18 driven by the reducer 26, a cam follower 29 that mates with a groove in the cylindrical cam 18, and a transmission mechanism connecting the cam follower 29 and the fish tail 20; the transmission mechanism is configured to convert the rotational motion of the cylindrical cam 18 into the reciprocating swing of the fish tail 20 to provide the main propulsion force;

[0008] A pair of multi-mode pectoral fin assemblies are symmetrically arranged on both sides of the fish head 2; each multi-mode pectoral fin assembly includes a pectoral fin body 6 and a propeller unit integrated on the pectoral fin body 6, the propeller unit includes a propeller motor 7 and a propeller 11 driven by the propeller motor 7; the pectoral fin body 6 is hinged to the fish head 2, and the pitch angle of the pectoral fin body 6 can be independently adjusted in a controlled manner.

[0009] Furthermore, the transmission mechanism includes:

[0010] A sliding member fixedly connected to the cam follower 29 is constrained to reciprocate linearly along a guide rail 21 fixed inside the fish body;

[0011] At least one elastic beam 19, one end of which is connected to the sliding member, and the other end of which is connected to the fish tail 20.

[0012] Furthermore, each of the multi-mode pectoral fin assemblies also includes a pectoral fin servo 9, which is fixed inside the fish head 2. The output shaft of the pectoral fin servo 9 is connected to the pectoral fin body 6 via a servo disk 8, and is used to drive and control the pitch angle of the pectoral fin body 6. In addition, the pectoral fin body 6 has a through hole at its center, and the propeller motor 7 is fixedly installed inside the through hole. The output shaft of the propeller motor 7 is connected to the propeller 11.

[0013] Furthermore, the transmission mechanism includes two independent sliding components, which are symmetrically arranged on both sides of the inside of the fish body with the cylindrical cam 18 as the center.

[0014] Each of the sliding components includes an elastic beam mount 23, a movable slider 22 fixed to the elastic beam mount 23 and slidably engaged with the guide rail 21, and two elastic beams 19.

[0015] One end of each of the two elastic beams 19 is fixed to both sides of the elastic beam mounting component 23 along the height direction of the robotic fish, and the other end of each of the two elastic beams 19 is connected to the corresponding position of the fish tail 20.

[0016] The cam follower 29 is a bearing, which is nested in the groove of the cylindrical cam 18 and is fastened to the corresponding elastic beam mounting member 23 by a nut 28 and a spring washer 27.

[0017] Furthermore, the end of the fish tail 20 is connected to the tail fin 5 via an elastic tail stalk 4.

[0018] Furthermore, it also includes an electronic control system, said electronic control system comprising:

[0019] A power supply module for supplying power to the drive motor 25, the pectoral fin servo motor 9 and the propeller motor 7;

[0020] Receiver 15 for receiving read commands;

[0021] Gyroscope 14 is used to sense the overall position and attitude of the robotic fish;

[0022] And an electronic speed controller 16 for independently or collaboratively controlling the drive motor 25, pectoral fin servo 9 and propeller motor 7 based on the read instructions and the overall position and attitude information of the robotic fish, so as to achieve switching and coordination of multiple motion modes.

[0023] Furthermore, the multiple motion modes include a cruise mode powered by tail swaying, a gliding mode achieved by pectoral fin pitch angle adjustment, a maneuver mode powered by propeller unit thrust, and a composite motion mode formed by at least two of the above modes.

[0024] Furthermore, the cruise mode is implemented in the following way:

[0025] The electronic control system controls the tail swing propulsion system to work, so that the drive motor 25 drives the cylindrical cam 18 to rotate continuously, and then drives the fish tail 20 and tail fin 5 to swing periodically through the transmission mechanism, generating forward propulsion force.

[0026] At the same time, the pectoral fin servo 9 in the multi-mode pectoral fin assembly is controlled to keep the pectoral fin bodies 6 on both sides parallel to the central axis of the robotic fish's body.

[0027] Furthermore, the gliding mode is achieved in the following way:

[0028] The electronic control system controls the tail swing propulsion system to provide forward propulsion.

[0029] Simultaneously, the pectoral fin servo 9 in the multi-mode pectoral fin assembly is controlled to cause the pectoral fin bodies 6 on both sides to deflect synchronously, forming a positive or negative angle of attack with the horizontal plane, thereby using the water flow to generate lift during forward movement, enabling the entire robotic fish to float or dive and glide.

[0030] Furthermore, the maneuvering mode is implemented in the following way:

[0031] The electronic control system controls the operation of the multi-mode pectoral fin assembly on at least one side, and starts the propeller motor 7 in the propeller unit on that side to drive the propeller 11 to generate thrust;

[0032] By independently controlling the output torque and / or steering of the propeller units on both sides, and / or coordinating the pitch angle of the pectoral fin body 6 to change the thrust direction, the robotic fish can achieve rapid turning, stationary rotation, lateral movement, or emergency braking.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] 1. The biomimetic robotic fish of this invention integrates and coordinates multiple motion modes, significantly improving overall maneuverability. This invention integrates a highly efficient BCF (body / tail fin) propulsion mode (tail sway), an energy-saving and stable MPF (central fin / paired fin) propulsion mode (pectoral fin gliding), and a highly responsive propeller propulsion mode into one unit. Through the coordinated control of the electronic control system, flexible and rapid switching between the three basic modes and multiple composite modes can be achieved, enabling the robotic fish to cruise efficiently for long durations, perform precise and stable control, and achieve highly maneuverable actions such as rapid turns and emergency braking. This fundamentally solves the bottleneck problem of insufficient maneuverability in robotic fish with a single propulsion mode.

[0035] 2. The biomimetic robotic fish of this invention features a compact structure and optimized space and weight distribution. The tail propulsion system employs a compact design of "single motor + cylindrical cam," replacing the traditional multi-joint, multi-motor drive scheme. This significantly simplifies the transmission chain, saves valuable internal space, and reduces overall weight. Simultaneously, the propeller motor is cleverly integrated into the through-hole of the pectoral fin, achieving reuse of functional components and efficient space utilization, making it possible to carry more mission equipment.

[0036] 3. The biomimetic robotic fish of this invention exhibits high biomimetic performance and propulsion efficiency. The streamlined, modular fish body shape effectively reduces swimming resistance. The tail drive, based on a cam-elastic beam mechanism, generates a more coherent and smooth oscillation waveform similar to that of real fish, resulting in high propulsion efficiency and low noise. The composite design of the pectoral fins and propeller allows the propeller's thrust direction to change with the pectoral fin's pitch angle, achieving vector propulsion and further enhancing the biomimetic maneuverability.

[0037] 4. Chinese invention patent CN118833371A, published on October 25, 2024, discloses a biomimetic fish structure that combines foldability and variable stiffness adjustment. This existing biomimetic fish structure differs from the biomimetic robotic fish of this invention in at least the following ways:

[0038] (1) The core transmission of the existing bionic fish structure is the friction transmission of "wheel disc-omnidirectional wheel". There is energy loss due to sliding friction, and it is easy to slip when the contact is poor, making the transmission unreliable.

[0039] The biomimetic robotic fish of this invention employs a closed-loop forced transmission using a cylindrical cam. This eliminates energy loss caused by friction and slippage, improving power utilization. The meshing relationship between the cam groove and the driven component (bearing) ensures stable and slip-free power transmission, adapting to complex underwater environments.

[0040] (2) The fish's body sway is ultimately driven by the spring's restoring force, which is a passive response. The sway amplitude and waveform are greatly affected by the spring's performance and water flow resistance, making them difficult to control precisely. Furthermore, long-term use will lead to performance degradation due to spring fatigue.

[0041] The biomimetic robotic fish of this invention features a tail whose swaying is directly and actively driven by a cam profile curve. This allows for the achievement of a preset optimal swaying waveform, resulting in stable and consistent swimming posture. It eliminates excessive reliance on the performance of elastic elements, and the swimming performance does not significantly degrade over time or under varying operating conditions.

[0042] 5. The biomimetic robotic fish tail-swing propulsion system of the present invention includes a drive motor disposed in the fish body, a reducer connected to the output end of the drive motor, a cylindrical cam driven by the reducer, a cam follower cooperating with the groove of the cylindrical cam, and a transmission mechanism connected between the cam follower and the fish tail; the transmission mechanism is configured to convert the rotational motion of the cylindrical cam into the reciprocating swing of the fish tail to provide the main propulsion force;

[0043] The groove profile of the cylindrical cam determines the oscillation pattern of the fish tail. By designing different groove profiles, different oscillation waveforms can be achieved to adapt to different swimming requirements. For example:

[0044] (1) The sinusoidal groove can make the fish tail swing smoothly and harmoniously, and swim stably.

[0045] (2) Using triangular or trapezoidal grooves can make the fish tail have a quick return characteristic at the swinging end, or produce more complex dynamic effects to obtain greater instantaneous thrust. Attached Figure Description

[0046] Figure 1 This is a schematic diagram of the overall structure of the multi-motion-mode bionic robotic fish with fin-propeller composite described in this invention.

[0047] Figure 2 This is a schematic diagram of the multi-mode pectoral fin assembly structure in the biomimetic robotic fish described in this invention;

[0048] Figure 3 This is a schematic diagram of the electronic control system structure in the biomimetic robotic fish described in this invention;

[0049] Figure 4 This is a schematic diagram of the drive system structure in the biomimetic robotic fish described in this invention;

[0050] Figure 5 This is an isometric view of the drive system in the biomimetic robotic fish described in this invention;

[0051] Figure 6 This is a cross-sectional view of the drive system in the biomimetic robotic fish described in this invention.

[0052] In the diagram: 1-End cap; 2-Fish head; 3-Skin; 4-Elastic tail fin; 5-Caudal fin; 6-Pectoral fin body; 7-Propeller motor; 8-Servo disc; 9-Pectoral fin servo; 10-Mounting bracket; 11-Propeller; 12-Battery I; 13-Battery II; 14-Gyroscope; 15-Receiver; 16-Electronic speed controller; 17-Battery III; 18-Cylindrical cam; 19-Elastic beam; 20-Fish tail; 21-Guide rail; 22-Moving slider; 23-Elastic beam mounting component; 24-Fish body; 25-Drive motor; 26-Reducer; 27-Spring washer; 28-Nut; 29-Cam follower. Detailed Implementation

[0053] This invention provides a biomimetic robotic fish with multiple motion modes actuated by an elastic beam integrating a propeller 11 on the pectoral fin 6. Multiple motion modes are achieved through gliding of the pectoral fin 6, maneuvering of the propeller 11, and swaying of the tail of the fish. This enables the biomimetic robotic fish to float and dive, turn, and swim in a straight line at high speed. It solves the problem of insufficient maneuverability caused by the single drive mode of existing biomimetic robotic fish under the BCF propulsion mechanism, and increases the reliability and responsiveness of the biomimetic fish in emergency obstacle avoidance and maneuvering.

[0054] This invention proposes a multi-mode configuration for a biomimetic robotic fish. A propeller 11 is integrated on the pectoral fin 6 of the biomimetic robotic fish, realizing a multi-mode design of tail swing propulsion, pectoral fin gliding, and propeller maneuvering, which greatly improves the maneuverability of the biomimetic robotic fish.

[0055] This invention adopts a modular design with a streamlined shape similar to a tuna, dividing the fish body into parts such as the head 2, body 24, and tail 20, reducing the resistance encountered by the robotic fish during swimming and facilitating assembly and disassembly.

[0056] This invention uses a single motor + reducer structure to drive the cylindrical cam 18 to rotate, converting the rotation of the cylindrical cam 18 into the reciprocating pull of the elastic beam 19. This abandons the traditional multi-joint multi-motor robotic fish design mode, simplifies the internal space of the fish, reduces the weight of the whole fish, and makes it possible to install equipment inside the fish in the future.

[0057] Specific implementation method one: Combining Figures 1 to 6This embodiment describes a biomimetic robotic fish with a multi-motion mode combining fins and propellers, comprising a streamlined fish body structure. The fish body structure includes a head 2, a body 24, and a tail 20 connected in sequence. A skin 3 is attached to the outer side of the fish body structure, and a tail fin 5 is connected to the end of the tail 20. It also includes:

[0058] The tail-swing propulsion system includes a drive motor 25 disposed within the fish body 24, a reducer 26 connected to the output end of the drive motor 25, a cylindrical cam 18 driven by the reducer 26, a cam follower 29 that mates with a groove in the cylindrical cam 18, and a transmission mechanism connecting the cam follower 29 and the fish tail 20; the transmission mechanism is configured to convert the rotational motion of the cylindrical cam 18 into the reciprocating swing of the fish tail 20 to provide the main propulsion force;

[0059] A pair of multi-mode pectoral fin assemblies are symmetrically arranged on both sides of the fish head 2; each multi-mode pectoral fin assembly includes a pectoral fin body 6 and a propeller unit integrated on the pectoral fin body 6, the propeller unit includes a propeller motor 7 and a propeller 11 driven by the propeller motor 7; the pectoral fin body 6 is hinged to the fish head 2, and the pitch angle of the pectoral fin body 6 can be independently adjusted in a controlled manner.

[0060] The fish head 2 has a conical end cap 1 at its front end, which makes the overall structure of the fish streamlined and effectively reduces swimming resistance. The rear end of the fish head 2 is connected to the mounting bracket 10, and the other end of the mounting bracket 10 is connected to the fish body 24. The drive motor 25 is equipped with a motor protective shell, which is connected to the mounting bracket 10. The drive motor 25 is fixed on the mounting bracket 10. The output shaft of the tail swing propulsion motor 25 is connected to the reducer 26. The end of the reducer 26 with the output shaft is connected to the mounting bracket 10 and fixed with bolts. The output shaft of the reducer 26 passes through the through hole in the center of the mounting bracket 10 and is connected to the cylindrical cam 18.

[0061] Specific Implementation Method Two: Combining Figures 1 to 6 This embodiment describes a transmission mechanism comprising:

[0062] A sliding member fixedly connected to the cam follower 29 is constrained to reciprocate linearly along a guide rail 21 fixed inside the fish body;

[0063] At least one elastic beam 19, one end of which is connected to the sliding member, and the other end of which is connected to the fish tail 20.

[0064] This configuration, with the guide rail and sliding component working together, provides precise linear guidance for the transmission, ensuring stable and reliable power transmission. The use of the elastic beam, on the one hand, realizes the conversion from rotational motion to oscillation; on the other hand, its own elastic deformation can store and release energy, making the fishtail oscillation more efficient and gentle, with a better biomimetic effect. Other components and connections are the same as in Specific Implementation Method One.

[0065] The guide rail 21 is longitudinally fixed to the mounting support 10, and its guiding direction is parallel to the central axis of the robot fish's body. It is used to precisely constrain the movable slider 22 and the elastic beam mounting component 23 connected to it to make linear reciprocating motion in the front-back direction.

[0066] Specific implementation method three: Combining Figures 1 to 6 In this embodiment, each of the multi-mode pectoral fin components further includes a pectoral fin servo motor 9, which is fixed inside the fish head 2. The output shaft of the pectoral fin servo motor 9 is connected to the pectoral fin body 6 via a servo disk 8, and is used to drive and control the pitch angle of the pectoral fin body 6. Furthermore, the pectoral fin body 6 has a through hole at its center, and the propeller motor 7 is fixedly installed inside the through hole. The output shaft of the propeller motor 7 is connected to the propeller 11.

[0067] This configuration, with independent pectoral fin servos driving the pectoral fins, enables precise and independent control of the pectoral fin pitch angle. This is fundamental for achieving gliding mode and adjusting the propeller thrust direction (vector propulsion), providing the robotic fish with crucial pitch and depth control capabilities. Embedding the propeller motor within a through-hole in the center of the pectoral fin is a highly integrated design. It not only saves space and makes the structure more compact but also ensures that the propeller thrust center coincides with or is close to the pectoral fin rotation center, reducing unnecessary torque and making control smoother and more precise when adjusting the pectoral fin angle. Other components and connections are the same as in specific implementation methods one or two.

[0068] Specific implementation method four: Combination Figures 1 to 6 This embodiment describes a transmission mechanism comprising two independent sliding components, which are symmetrically arranged on both sides of the interior of the fish with the cylindrical cam 18 as the center.

[0069] Each of the sliding components includes an elastic beam mount 23, a movable slider 22 fixed to the elastic beam mount 23 and slidably engaged with the guide rail 21, and two elastic beams 19.

[0070] One end of each of the two elastic beams 19 is fixed to both sides of the elastic beam mounting component 23 along the height direction of the robotic fish, and the other end of each of the two elastic beams 19 is connected to the corresponding position of the fish tail 20.

[0071] The cam follower 29 is a bearing, which is nested in the groove of the cylindrical cam 18 and is fastened to the corresponding elastic beam mounting member 23 by a nut 28 and a spring washer 27.

[0072] This configuration, employing two symmetrically arranged sliding components and four elastic beams, forms a balanced and robust drive frame. This symmetrical structure balances lateral forces during the drive process, improving system stability and preventing jamming. The four elastic beams drive the upper and lower parts of the fishtail more evenly, promoting a more coordinated and efficient large-amplitude "S"-shaped motion waveform, significantly improving propulsion efficiency. Other components and connections are the same as in specific implementation methods one, two, or three.

[0073] Specific Implementation Method Five: Combining Figures 1 to 6 In this embodiment, the end of the fish tail 20 is connected to the tail fin 5 via an elastic tail stalk 4.

[0074] This configuration, by placing an elastic caudal peduncle 4 between the end of the fish tail 20 and the caudal fin 5, enables a smoother, more biomimetic tail waveform transmission. Other components and connections are the same as in specific embodiments one, two, three, or four.

[0075] Specific Implementation Method Six: Combination Figures 1 to 6 This embodiment further includes an electronic control system, which includes:

[0076] A power supply module for supplying power to the drive motor 25, the pectoral fin servo motor 9 and the propeller motor 7;

[0077] Receiver 15 for receiving read commands;

[0078] Gyroscope 14 is used to sense the overall position and attitude of the robotic fish;

[0079] And an electronic speed controller 16 for independently or collaboratively controlling the drive motor 25, pectoral fin servo 9 and propeller motor 7 based on the read instructions and the overall position and attitude information of the robotic fish, so as to achieve switching and coordination of multiple motion modes.

[0080] With this configuration, the electronic control system enables multi-mode collaborative operation. Independent power modules prevent power interference between different motors; real-time attitude information provided by the gyroscope is crucial for stable control and autonomous mode switching; the controller fully utilizes the potential of the mechanical structure through independent or collaborative control of the three power systems, ultimately achieving intelligent switching and seamless integration of multiple motion modes. Other components and connections are the same as in specific implementation methods one, two, three, four, or five.

[0081] The power module includes battery I12, battery II13 and battery III17. Battery I12 is used to power the drive motor 25. Battery II13 and battery III17 are used to power the propeller motor 7 and the pectoral fin servo motor 9 of the two multi-mode pectoral fin assemblies, respectively.

[0082] Specific implementation method seven: Combining Figures 1 to 6 This embodiment describes multiple motion modes, including a cruise mode powered by tail sway, a gliding mode achieved by adjusting the pitch angle of the pectoral fins, a maneuver mode powered by the propeller unit, and a composite motion mode formed by combining at least two of the above modes.

[0083] This configuration clearly defines the three basic movement modes and their composite modes of the biomimetic robotic fish. Compared to single-mode robotic fish, it can select the most suitable movement mode according to task requirements (such as long-distance patrolling, covert approach, and operation in confined spaces), achieving on-demand allocation of performance and greatly expanding its application scenarios. Other components and connections are the same as in specific implementation methods one, two, three, four, five, or six.

[0084] Specific implementation method eight: Combination Figures 1 to 6 This embodiment describes a cruise mode implemented in the following manner:

[0085] The electronic control system controls the tail swing propulsion system to work, so that the drive motor 25 drives the cylindrical cam 18 to rotate continuously, and then drives the fish tail 20 and tail fin 5 to swing periodically through the transmission mechanism, generating forward propulsion force.

[0086] At the same time, the pectoral fin servo 9 in the multi-mode pectoral fin assembly is controlled to keep the pectoral fin bodies 6 on both sides parallel to the central axis of the robotic fish's body.

[0087] This configuration fully leverages the advantages of biomimetic tail-wagging propulsion—high efficiency and low noise—while minimizing drag by retracting the pectoral fins into a streamlined state. This provides an optimal movement strategy for the robotic fish to perform long-range, long-endurance reconnaissance and cruising missions. Other components and connections are the same as in specific implementation methods one, two, three, four, five, six, or seven.

[0088] Specific Implementation Method Nine: Combining Figures 1 to 6 This embodiment describes a gliding mode implemented in the following manner:

[0089] The electronic control system controls the tail swing propulsion system to provide forward propulsion.

[0090] Simultaneously, the pectoral fin servo 9 in the multi-mode pectoral fin assembly is controlled to cause the pectoral fin bodies 6 on both sides to deflect synchronously, forming a positive or negative angle of attack with the horizontal plane, thereby using the water flow to generate lift during forward movement, enabling the entire robotic fish to float or dive and glide.

[0091] This configuration cleverly converts the forward thrust from the tail into vertical lift via adjustable pectoral fins, achieving depth adjustment without increasing propulsion power consumption. It is particularly suitable for missions requiring sustained depth maintenance or quiet underwater operation. Other components and connections are the same as in implementation methods one, two, three, four, five, six, seven, or eight.

[0092] Specific Implementation Method Ten: Combining Figures 1 to 6 This embodiment describes a mobility mode implemented in the following manner:

[0093] The electronic control system controls the operation of the multi-mode pectoral fin assembly on at least one side, and starts the propeller motor 7 in the propeller unit on that side to drive the propeller 11 to generate thrust;

[0094] By independently controlling the output torque and / or steering of the propeller units on both sides, and / or coordinating the pitch angle of the pectoral fin body 6 to change the thrust direction, the robotic fish can achieve rapid turning, stationary rotation, lateral movement, or emergency braking.

[0095] This configuration leverages the rapid response and adjustable thrust vector of propeller propulsion. Through differential control or vector thrust control, it endows the robotic fish with superior capabilities for emergency obstacle avoidance, precise positioning, and rapid turning in complex underwater environments, overcoming the core deficiency of insufficient maneuverability in traditional biomimetic robotic fish. Other components and connections are the same as in embodiments one, two, three, four, five, six, seven, eight, or nine.

[0096] Example 1: The bionic fish's tail 20 swings to achieve forward swimming.

[0097] The drive motor 25 of the bionic fish keeps rotating, driving the reducer 26 to rotate. The reducer 26 reduces the speed of the output shaft and increases the torque of the output shaft, causing the cylindrical cam 18 to rotate at an appropriate speed. The bearing embedded in the cam groove will reciprocate along the guide rail 21 along the cam axis. The elastic beam mounting part 23 connected to the bearing will also reciprocate accordingly. The elastic beam 19 installed above and below the elastic beam mounting part 23 is pulled to complete the push-pull action. Relying on the deformation of the elastic beam 19 and the storage and release of elasticity, the fish tail 20 swings. The elastic tail peduncle 4 and tail fin 5 of the fish tail 20 interact with the water to obtain thrust, realizing the forward swimming of the bionic fish.

[0098] Example 2: Gliding of a Bionic Fish

[0099] The bionic fish maintains the swinging state of the tail 20 in Embodiment 1. The pectoral fin servo motors 9 located on both sides of the fish head 2 rotate, so that the pectoral fin body 6 makes an angle with the horizontal plane. During the propulsion process of the bionic fish, it relies on the water flow to obtain upward or downward fluid force, and finally realizes the gliding action of the bionic fish.

[0100] Example 3: Paddle Propulsion of a Bionic Fish

[0101] The output shaft of the pectoral fin servo motor 9 on one side of the bionic fish rotates 90°, while the pectoral fin servo motor 9 on the other side remains stationary, so that one of the two pectoral fin bodies 6 of the bionic fish remains horizontal and the other remains vertical. The propeller motor 7 of the pectoral fin body 6 in the vertical position starts, and the bionic fish turns by relying on the thrust of the propeller 11.

[0102] Working principle

[0103] Combination Figures 1 to 6 The working principle of the multi-motion-mode biomimetic robotic fish with fin-propeller composite described in this invention is explained as follows:

[0104] The core working principle of this invention is based on a highly integrated mechanical structure, which dynamically allocates three propulsion mechanisms through intelligent decision-making by the electronic control system.

[0105] Power transmission path:

[0106] When tail thrust is required, drive motor 25 starts, and after adjusting torque and speed via reducer 26, drives cylindrical cam 18 to rotate. Cam follower 29, embedded in cam groove, converts the cam's rotational motion into its own axial reciprocating motion, driving the sliding assembly, including elastic beam mount 23 and movable slider 22, fixed to it to perform precise linear reciprocating motion along guide rail 21. The sliding assembly then pushes and pulls the fish tail 20 via elastic beam 19 connected at both ends. Utilizing the deformation and recovery of the elastic beam, the fish tail and tail fin 5 are ultimately driven to produce biomimetic oscillation, thereby obtaining forward propulsion.

[0107] Multi-mode collaborative control:

[0108] Cruise mode: The electronic control system only activates the tail swing propulsion system and controls the pectoral fin servo 9 to keep the two pectoral fins 6 in a streamlined state parallel to the body, so as to achieve low-drag, high-efficiency straight-line navigation.

[0109] Gliding mode: Based on the forward propulsion provided by the tail, the electronic control system controls the pectoral fin servo motor 9 to synchronously deflect the two pectoral fins 6 at a specific angle of attack. At this time, the water flowing over the pectoral fins generates lift, thereby enabling the robotic fish to rise or dive during forward movement. This mode has low energy consumption and low noise.

[0110] Maneuvering Mode: The electronic control system can independently control the start of one or both propeller motors 7 to generate thrust. By causing the two propellers 11 to generate differential thrust, reverse thrust, or coordinately control the pitch angle of the pectoral fins 6 to change the direction of thrust, rapid turns, stationary turns, lateral movements, or emergency braking can be achieved. This mode has a rapid response and extremely high maneuverability.

[0111] Mode Combination: The above basic modes can be combined according to the needs of complex environments. For example, while cruising with the tail swaying, a single propeller can be activated for auxiliary steering; or the propeller can be activated during gliding ascent to accelerate upward. The electronic control system receives commands through receiver 15 and transmits them to electronic speed controller 16. Combined with attitude information fed back from gyroscope 14, electronic speed controller 16 performs real-time calculations and outputs control signals to each motor and servo, ultimately achieving stable, flexible, and intelligent multi-mode swimming.

[0112] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-mode biomimetic robotic fish with a fin-propeller composite structure, comprising a streamlined fish body structure, wherein the fish body structure includes a fish head (2), a fish body (24), and a fish tail (20) connected in sequence, wherein a skin (3) is attached to the outside of the fish body structure, and a tail fin (5) is connected to the end of the fish tail (20); characterized in that, Also includes: The tail-swing propulsion system includes a drive motor (25) disposed in the fish body (24), a reducer (26) connected to the output end of the drive motor (25), a cylindrical cam (18) driven by the reducer (26), a cam follower (29) cooperating with the groove of the cylindrical cam (18), and a transmission mechanism connected between the cam follower (29) and the fish tail (20); the transmission mechanism is configured to convert the rotational motion of the cylindrical cam (18) into the reciprocating swing of the fish tail (20) to provide the main propulsion force; A pair of multi-mode pectoral fin assemblies are symmetrically arranged on both sides of the fish head (2); each multi-mode pectoral fin assembly includes a pectoral fin body (6) and a propeller unit integrated on the pectoral fin body (6), the propeller unit includes a propeller motor (7) and a propeller (11) driven by the propeller motor (7); the pectoral fin body (6) is hinged to the fish head (2), and the pitch angle of the pectoral fin body (6) can be independently adjusted in a controlled manner.

2. The biomimetic robotic fish according to claim 1, characterized in that, The transmission mechanism includes: A sliding member fixedly connected to the cam follower (29) is constrained to reciprocate linearly along a guide rail (21) fixed inside the fish body; At least one elastic beam (19) is provided, one end of which is connected to the sliding member and the other end of which is connected to the fish tail (20).

3. The biomimetic robotic fish according to claim 1 or 2, characterized in that, Each of the multi-mode pectoral fin assemblies also includes a pectoral fin servo (9), which is fixed inside the fish head (2). The output shaft of the pectoral fin servo (9) is connected to the pectoral fin body (6) through the servo disk (8) to drive and control the pitch angle of the pectoral fin body (6). Furthermore, the pectoral fin body (6) has a through hole at its center, and the propeller motor (7) is fixedly installed inside the through hole. The output shaft of the propeller motor (7) is connected to the propeller (11).

4. The biomimetic robotic fish according to claim 2, characterized in that, The transmission mechanism includes two independent sliding components, which are symmetrically arranged on both sides of the inside of the fish body with the cylindrical cam (18) as the center. Each of the sliding components includes an elastic beam mount (23), a movable slider (22) fixed to the elastic beam mount (23) and slidingly engaged with the guide rail (21), and two elastic beams (19). One end of each of the two elastic beams (19) is fixed to both sides of the elastic beam mounting component (23) along the height direction of the robotic fish, and the other end of each of the two elastic beams (19) is connected to the corresponding position of the fish tail (20). The cam follower (29) is a bearing, which is nested in the groove of the cylindrical cam (18) and is fastened to the corresponding elastic beam mounting part (23) by a nut (28) and a spring washer (27).

5. The biomimetic robotic fish according to claim 1, characterized in that: The end of the fish tail (20) is connected to the tail fin (5) by an elastic tail peduncle (4).

6. The biomimetic robotic fish according to claim 1, characterized in that, It also includes an electronic control system, which comprises: A power supply module for supplying power to the drive motor (25), pectoral fin servo (9) and propeller motor (7); Receiver (15) for receiving read commands; A gyroscope (14) used to sense the overall position and attitude of the robotic fish. And an electronic speed controller (16) for independently or collaboratively controlling the drive motor (25), pectoral fin servo (9) and propeller motor (7) based on the read instructions and the overall position and attitude information of the robotic fish, so as to realize the switching and coordination of multiple motion modes.

7. The biomimetic robotic fish according to claim 6, characterized in that, The various motion modes include a cruise mode powered by tail sway, a gliding mode achieved by adjusting the pitch angle of the pectoral fins, a maneuver mode powered by the propeller unit, and a composite motion mode formed by combining at least two of the above modes.

8. The biomimetic robotic fish according to claim 7, characterized in that, The cruise mode is achieved in the following way: The electronic control system controls the tail swing propulsion system to work, so that the drive motor (25) drives the cylindrical cam (18) to rotate continuously, and then drives the fish tail (20) and tail fin (5) to swing periodically through the transmission mechanism, generating forward propulsion force; At the same time, the pectoral fin servo (9) in the multi-mode pectoral fin assembly is controlled so that the pectoral fin bodies (6) on both sides are kept in a posture parallel to the central axis of the robot fish's body.

9. The biomimetic robotic fish according to claim 7, characterized in that, The gliding mode is achieved in the following way: The electronic control system controls the tail swing propulsion system to provide forward propulsion. At the same time, the pectoral fin servo (9) in the multi-mode pectoral fin assembly is controlled to make the pectoral fin bodies (6) on both sides deflect synchronously, forming a positive angle of attack or a negative angle of attack with the horizontal plane, thereby using the water flow to generate lift during the forward movement, so as to realize the overall floating or diving gliding of the robot fish.

10. The biomimetic robotic fish according to claim 7, characterized in that, The maneuver mode is achieved in the following way: The electronic control system controls the operation of at least one of the multi-mode pectoral fin assemblies, and starts the propeller motor (7) in the propeller unit on that side to drive the propeller (11) to generate thrust; By independently controlling the output torque and / or steering of the propeller units on both sides, and / or coordinating the pitch angle of the pectoral fin body (6) to change the thrust direction, the robotic fish can achieve rapid turning, stationary turning, lateral movement or emergency braking.

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