A sailfish-like robot propelled by coordinated dorsal and caudal fins and its coupled motion method

Abstract

This invention relates to a sailfish-inspired robot with coordinated dorsal and caudal fin propulsion and its coupled motion method, belonging to the field of underwater robotics. It consists of a front section, a dorsal fin propulsion structure, and a caudal fin propulsion structure. The front section mainly includes an upper and lower anterior cavity, a center of gravity adjustment device, a gyroscope, an infrared obstacle avoidance sensor, a camera, and lighting equipment. The dorsal fin propulsion structure mainly includes a dorsal fin, a roller cover, a roller body, an unfolding and folding structure, and a waterproof servo motor on the back. The caudal fin propulsion structure has M joints, each including an upper and lower joint cavity and a waterproof servo motor. The robot's coordinated movement of the dorsal and caudal fins, and the coupled movement of the dorsal and caudal fins, improves the robot's swimming speed and maneuverability. It can be used as an underwater platform for ecological observation, underwater exploration, reconnaissance, and other fields.

Description

Technical Field

[0001] This invention belongs to the field of underwater robot application technology, specifically relating to a sailfish-inspired robot with coordinated dorsal and caudal fin propulsion and its coupled motion method. It can be used as an underwater platform in fields such as ecological observation, underwater exploration, and reconnaissance, and has broad application prospects. Technical Background

[0002] In ocean exploration, human diving is limited by factors such as water current speed, depth, and water quality, and the underwater environment is relatively harsh. Therefore, underwater robots are gradually replacing humans to perform many high-risk or inhuman underwater tasks. Aquatic organisms, which live underwater for extended periods, possess natural advantages such as high propulsion efficiency, high speed, and strong maneuverability. Fish are a prime example, making the design of robotic fish as underwater platforms of significant importance.

[0003] In terms of swimming performance, sailfish rank among the top fish. Therefore, this invention uses the sailfish as a biomimetic model to create a robotic fish with high swimming performance, providing a more effective platform for exploring and developing marine resources. During observations of sailfish swimming, we discovered that the coordinated operation of the sailfish's dorsal and caudal fins is one of the secrets to its high swimming performance. Therefore, designing a sailfish-inspired robot with coordinated dorsal and caudal fin propulsion has significant research and engineering value.

[0004] Zhang Runfeng proposed a multi-mode driven bionic robotic fish (patent application number: 202020967060.1), which features a sail-driven mode. In this mode, only the dorsal fin functions as a sail, without coordination with the tail fin's movement, resulting in suboptimal motion. Furthermore, the invention's structure limits the size of the dorsal fin, further restricting its function. The Institute of Automation, Chinese Academy of Sciences, proposed a bionic robotic fish for environmental monitoring (patent applications: 201921369826.X, 201910774961.0), mentioning a dorsal fin. However, the dorsal fin has no degrees of freedom, its function being solely to provide mounting positions for GPS and wireless communication antennas, exhibiting significant limitations. The Institute of Automation, Chinese Academy of Sciences, proposed a multi-control surface robotic fish with embedded vision (patent application number: 201110139019.0), mentioning the use of the dorsal fin and other fins for balance to ensure head stability. However, the dorsal fin has only one degree of freedom and cannot fold into the robotic fish's body, increasing drag during swimming, increasing energy consumption, and reducing swimming speed. Shenzhen Bermuda Industrial Co., Ltd. has proposed a biomimetic fish-tail underwater robot (patent application number: 202011123154.1). However, its dorsal fin only has one degree of freedom for oscillation, exhibiting the shortcomings of the aforementioned patent. In summary, the collaborative propulsion of the dorsal and caudal fins in robotic fish has not yet been effectively studied. Summary of the Invention

[0005] The purpose of this invention is to provide an underwater exploration platform with high swimming performance and strong environmental adaptability. Using the sailfish as a biomimetic model, a sailfish-inspired robot with coordinated dorsal and caudal fin propulsion is designed. High swimming performance is achieved through the coordinated propulsion of the dorsal and caudal fins, and a method for coupling the dorsal and caudal fins' motion is provided.

[0006] The aforementioned sailfish-like robot, which uses a coordinated propulsion system of dorsal and caudal fins, is characterized by comprising a fish-shaped front section, a dorsal fin propulsion structure, and a caudal fin propulsion structure.

[0007] The aforementioned front part of the fish mainly includes the lower front cavity and the upper front cavity, the front cover, and the conical beak that reduces water resistance; it also includes a lithium battery, control board, and center of gravity adjustment device installed between the lower front cavity and the upper front cavity; it also includes a gyroscope, infrared obstacle avoidance sensor, camera, and lighting equipment installed between the lower front cavity and the front cover, which together form the robot's sensor part; the front part mainly houses the control components and sensors, playing a role in control and perception; the overall front part of the fish has a streamlined shape, which effectively reduces water resistance, increases swimming speed, and reduces energy consumption.

[0008] The aforementioned dorsal fin propulsion structure mainly includes a dorsal fin, a roller cover, a roller body, an unfolding and folding structure, a waterproof dorsal servo, transmission components, and a servo disc. The roller body is installed in the upper front cavity of the fish and engages with it via front and rear bearings. The unfolding and folding structure is fixed to the side of the roller body with screws, and the roller cover is fixed to the roller body with screws, providing a groove for the dorsal fin and unfolding and folding structure to unfold. The dorsal fin is installed on the unfolding and folding structure using a combination of screws, nuts, and washers. The waterproof dorsal servo is fixed in the upper front cavity of the fish, and the roller body engages with it via a transmission component. The moving parts and servo disk are connected to the output shaft of the waterproof servo on the back. The waterproof servo on the back drives the roller to swing back and forth, so that the roller and the structure fixed to it have different swing amplitudes, and finally drive the dorsal fin to swing back and forth. The dorsal fin propulsion structure has two degrees of freedom and they do not interfere with each other. The first degree of freedom is the rotational degree of freedom, that is, the reciprocating swing of the roller and the structure fixed to it; the second degree of freedom is the unfolding and folding degree of freedom, that is, the full unfolding and folding of the unfolding and folding structure. This provides the dorsal fin with two independent degrees of freedom, enabling it to move flexibly and effectively improving the flexibility of the sailfish-like robot.

[0009] The aforementioned unfolding and folding structure mainly includes a motor, a motor drive rod, a nut slider, a fixed rod, a follower rod, and N parallel connecting rods, where N is a natural number from 4 to 8. The fixed rod is fixed to the roller body by a combination of screws, nuts, and washers, remaining stationary. All N connecting rods are connected to the fixed rod and follower rod by screws, forming a single-degree-of-freedom multi-link mechanism. One end of the motor drive rod is connected to the nut slider, and the other end is connected to one of the N parallel connecting rods. The motor has a threaded rod that engages with the nut in the nut slider. When the motor rotates, it drives the nut slider forward and backward, which in turn drives the motor drive rod, controlling the unfolding and folding of the structure to achieve different degrees of unfolding and folding. The unfolding and folding structure provides one degree of freedom for the dorsal fin propulsion structure, namely, the degree of freedom for unfolding and folding.

[0010] The aforementioned tail fin propulsion structure has a total of M joints, where M is a natural number from 3 to 5. Each joint includes an upper joint cavity, a lower joint cavity, and a waterproof servo motor. The waterproof servo motor is fixed in the lower joint cavity, and the upper and lower joint cavities are fixed together with screws. The bottom of the lower joint cavity is connected to the lower joint cavity of the previous joint or the robot structure in front of it via a bearing. The servo motor disk of the waterproof servo motor is connected to the top of the upper joint cavity of the previous joint or the robot structure in front of it. The tail fin is connected to the last joint via screws. The tail fin propulsion structure has multiple joints, which resemble the joints of a fish skeleton, making its movement more similar to that of a real fish and effectively improving the flexibility of the sailfish-like robot.

[0011] The aforementioned center of gravity adjustment device mainly includes a center of gravity adjustment motor, a slider, a nut, a linear bearing, a light shaft, a lead screw, and a counterweight box;

[0012] The nut and linear bearing are installed in the slider; the slider is mounted on the optical shaft via the linear bearing; the lead screw is connected to the output shaft of the center of gravity adjustment motor, and the lead screw and the nut in the slider form a lead screw-nut pair; the counterweight box is fixed on the slider; a lead weight is placed in the counterweight box and fixed to the slider with 3M adhesive; using the lead screw-nut pair, when the center of gravity adjustment motor rotates, it will drive the slider to move, which in turn drives the counterweight box and the lead weight to move, ultimately achieving the adjustment of the center of gravity; two optical shafts and one lead screw pass through the slider and are fixed inside the fish body to prevent the slider and counterweight box from moving left, right, up, or down, thus improving the stability of the center of gravity adjustment device; the center of gravity adjustment device has a simple structure, is easy to install, and has high reliability in center of gravity adjustment;

[0013] The aforementioned robot sensor components are characterized by: a lithium battery and counterweight installed at the bottom of the lower front cavity of the fish to lower its center of gravity; a gyroscope fixed to the control board to obtain the robot fish's posture during swimming; an infrared obstacle avoidance sensor installed in the front area of ​​the lower front cavity to measure the distance to obstacles in real time; a camera installed in the front chamber of the lower front cavity, with two lighting devices on either side to provide illumination for the robot fish; when the gyroscope detects abnormalities such as yaw, tilt, drooping, or pitching during robot movement, it coordinates the tail fin, dorsal fin, and center of gravity adjustment device to restore the robot to a normal posture; the infrared obstacle avoidance sensor enables the robot fish to take timely obstacle avoidance actions when encountering obstacles; the camera captures underwater images in real time and transmits the images, while the two lighting devices ensure shooting quality in dark environments. The integration of multiple sensors on the robot effectively improves its task performance capabilities and increases its practicality as an underwater exploration platform.

[0014] Both the dorsal fin propulsion structure and the caudal fin propulsion structure have female waterproof aviation connectors, while the front part of the fish has two male waterproof aviation connectors, corresponding to the two mentioned above. The waterproof aviation connectors ensure the independence of each component and the waterproofness of the control line connection. Since each part is a separate module, it can be tested independently or quickly replaced when damaged, which facilitates robot maintenance, improves efficiency, and makes it more suitable as an underwater research platform.

[0015] The method for coupled movement of the dorsal fin and caudal fin according to the present invention is characterized by comprising the following processes:

[0016] (I) Dorsal fin unfolding and folding motion process: When the motor rotates, the nut slider moves forward or backward, causing the unfolding and folding structure to unfold or fold.

[0017] (II) The coordinated movement of the dorsal and caudal fins:

[0018] The first motion mode is rapid forward movement. In this motion mode, the unfolded folding structure is completely folded inside the robot's body, causing the dorsal fin to fold up, and the tail fin propulsion structure provides thrust. Because the dorsal fin is folded up, the drag when the robot moves forward is reduced. Combined with the robot's streamlined shape, the robot can achieve a high propulsion speed.

[0019] The second movement mode is a high-mobility movement mode. In this mode, the folding structure unfolds, and the dorsal and caudal fins coordinate with each other. The coordination between the dorsal and caudal fins during dorsal fin deployment involves the following two movement methods:

[0020] Movement Mode 2-1: When the sailfish-like robot turns left, its dorsal fin swings to the left side of its body and remains stationary, while its tail fin swings back and forth from side to side or slightly to the right. When the sailfish-like robot turns right, its dorsal fin swings to the right side of its body and remains stationary, while its tail fin swings back and forth from side to side or slightly to the left. In both cases, the tail fin provides propulsion, and the dorsal fin acts like a rudder, making turning faster and the turning radius smaller. The waterproof servo on the back drives the swing of the dorsal fin, and the amplitude of the swing is adjusted by the waterproof servo on the back. Therefore, when the dorsal fin swings to the left or right side of the body and remains stationary, the dorsal fin has multiple different amplitudes corresponding to different stationary positions. The unfolding and folding structure adjusts the degree of unfolding and folding of the dorsal fin, so when the dorsal fin is unfolded, it has multiple different degrees of unfolding and folding. This coordinates with the tail fin, and by combining the two parameters of the stationary position of the dorsal fin and the degree of unfolding and folding, more specific movement modes can be formed. Here, the left or right reciprocating swing refers to the position of the central axis being slightly to the left or right during the reciprocating swing.

[0021] Movement mode 2-2: When the sailfish-like robot turns left, the dorsal fin swings back and forth to the left, and the tail fin swings back and forth to the left or to the right; when the sailfish-like robot turns right, the dorsal fin swings back and forth to the right, and the tail fin swings back and forth to the left or to the right; in both cases, the tail fin provides the main propulsion, and the dorsal fin provides a small amount of propulsion and also has a certain rudder-like function, making the turning faster and the turning radius smaller; the waterproof back servo (11) drives the swing of the dorsal fin, and the swing amplitude of the dorsal fin is adjusted by the waterproof back servo (11), and the dorsal fin has a variety of different swing amplitudes; the unfolding and folding structure (6) adjusts the unfolding and folding degree of the dorsal fin, so when the dorsal fin is unfolded, the dorsal fin has a variety of different unfolding and folding degrees; when there is a difference between the phase of the dorsal fin swing and the phase of the tail fin swing, different phase differences are formed; the dorsal fin and the tail fin coordinate with each other, and the three parameters of the dorsal fin swing amplitude, unfolding and folding degree and phase difference are arranged and combined to form more specific movement modes;

[0022] These two movement modes are designed for different underwater environments. Movement mode one, which is fast forward movement, gives the sailfish-like robot a high swimming speed, making it suitable for environments with relatively calm water flow and few obstacles, and enabling it to complete tasks quickly. Movement mode two, which is high-mobility movement, gives the sailfish-like robot high flexibility, making it suitable for environments with relatively rapid water flow and many obstacles, thus improving its survivability.

[0023] (III) The process of diving and surfacing:

[0024] In this movement mode, the tail fin propulsion structure is combined with the center of gravity adjustment device, which has the advantage of high reliability and has the following two movement modes:

[0025] Movement Mode 3-1: Inclined Diving and Ascending Movement. In this movement mode, for the diving movement, the center of gravity adjustment motor rotates to move the counterweight box forward, which in turn causes the head of the robotic fish to droop. Then, the tail fin swings back and forth to make the robot swim forward and downward, finally completing the diving movement. For the ascending movement, the center of gravity adjustment motor rotates to move the counterweight box backward, which in turn causes the head of the robotic fish to tilt upward. Then, the tail fin swings back and forth to make the robot swim forward and upward, finally completing the ascending and descending movement.

[0026] Motion Mode 3-2: Spiral Descent and Ascent Motion. In this mode, for the descent motion, the center of gravity adjustment motor rotates, causing the counterweight box to move forward, which in turn causes the robotic fish's head to droop continuously. At the same time, the tail fin swings back and forth to the right or left, causing the robot to turn and ultimately complete the descent motion. The tail fin swinging back and forth to the right is a counterclockwise spiral descent motion; the tail fin swinging back and forth to the left is a clockwise spiral descent motion. For the ascent motion, the center of gravity adjustment motor rotates, causing the counterweight box to move backward, which in turn causes the robotic fish's head to tilt upward. At the same time, the tail fin swings back and forth to the right or left, causing the robot to turn and ultimately complete the ascent motion. The tail fin swinging back and forth to the right is a counterclockwise spiral ascent motion; the tail fin swinging back and forth to the left is a clockwise spiral ascent motion.

[0027] The method for coupled movement of the dorsal fin and caudal fin according to the present invention is characterized by comprising the following processes:

[0028] For the second motion mode of the coordinated movement of the dorsal and caudal fins, namely high-mobility motion, after a large number of experiments, the following parameters make the design and control of the sailfish-like robot more convenient and achieve a good control effect; if the angle of the swing of the roller (5) around its own axis is denoted as the swing amplitude angle, and α is used, the value range of α is as follows: α = 0, 0 < α < 30°, α = 30°, 30° < α < 60° and α = 60°, which correspond to the swing amplitude of the dorsal fin as stationary, small swing, medium swing and large swing respectively. Swinging and full swinging; if the angle formed by the foremost link among the N parallel links of the unfolded folding structure (6) and the central axis of the sailfish-like robot is used as the standard, it is denoted as the unfolding folding angle, and represented by β. The value range of β is as follows: β = 0, 0 < β < 30°, β = 30°, 30° < β < 60° and β = 60°, which correspond to the degree of unfolding of the dorsal fin (1) as fully folded, partially unfolded, half-unfolded, mostly unfolded and fully unfolded; the phase difference that exists when the dorsal fin and tail fin swing is represented by express, n = 0, 1, 2, ..., k-1, k ≥ 1 and l is divisible by 360°;

[0029] Regarding movement mode 2-1, when the dorsal fin is swung to the left or right side of the body and remains stationary, the dorsal fin has four different amplitudes corresponding to stationary positions: 0 < α < 30°, α = 30°, 30° < α < 60°, and α = 60°. When the dorsal fin is spread out, it has four different degrees of spread and folding: 0 < β < 30°, β = 30°, 30° < β < 60°, and β = 60°, which are partially spread, half-spread, mostly spread, and fully spread, respectively. These are coordinated with the caudal fin. Combining the two parameters of the stationary position of the dorsal fin and the degree of spread and folding, there are a total of 4 × 4 = 16 specific movement modes.

[0030] Regarding movement mode 2-2, when the dorsal fin swings, it has four different amplitudes: 0 < α < 30°, α = 30°, 30° < α < 60°, and α = 60°, corresponding to the swing amplitudes of stationary, small-amplitude, medium-amplitude, large-amplitude, and fully swinging, respectively. When the dorsal fin is spread, it has four different degrees of spread and folding: 0 < β < 30°, β = 30°, 30° < β < 60°, and β = 60°, corresponding to partial spread, half-spread, mostly spread, and fully spread, respectively. There are k different phase differences between the dorsal fin swing and the caudal fin swing. By coordinating the dorsal and caudal fins and combining the three parameters of swing amplitude, spread and folding degree, and phase difference, there are a total of 4 × 4 × k = 16·k specific movement modes. If l = 30°, then k = 12, meaning there are 4 × 4 × 12 = 192 specific movement modes.

[0031] Compared with the prior art, the present invention has the following advantages:

[0032] 1. This invention enables the coordinated movement of the dorsal and caudal fins of a sailfish-like robot, and effectively improves the swimming speed and maneuverability of the sailfish-like robot through the coupled movement of the dorsal and caudal fins.

[0033] 2. In this invention, not only does the tail fin have multiple joints, but the dorsal fin also has two degrees of freedom, effectively simulating the movement of a fish and providing the robot platform with a wide variety of movement modes, enabling it to cope with different underwater environments and improving the survivability and environmental adaptability of the sailfish-like robot.

[0034] 3. This invention uses multiple sensors to coordinate the robot's movement to restore it to normal when the robot experiences abnormal problems such as yaw, tilt, droop, or pitch. In addition, it also obtains effective environmental information such as obstacle information and images, which makes it more practical. Attached Figure Description

[0035] Figure 1 This is a 3D diagram of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0036] Figure 2 This is an exploded view of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0037] Figure 3 This is a three-dimensional diagram of the dorsal fin propulsion structure of the sailfish-like robot with coordinated dorsal and caudal fin propulsion as described in this invention.

[0038] Figure 4 This is an exploded view of the dorsal fin propulsion structure of the sailfish-like robot with coordinated dorsal and caudal fin propulsion as described in this invention.

[0039] Figure 5 This is an exploded view of the unfolded and folded structure of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0040] Figure 6 This is a three-dimensional diagram of the tail fin propulsion structure of the sailfish-like robot with coordinated dorsal and caudal fin propulsion as described in this invention.

[0041] Figure 7 This is an exploded view of the tail fin propulsion structure of the sailfish-like robot with coordinated dorsal and caudal fin propulsion as described in this invention.

[0042] Figure 8 This is a three-dimensional view of the front part of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0043] Figure 9 This is an exploded view of the front part of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0044] Figure 10 This is an exploded view of the center of gravity adjustment structure of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0045] Figure 11 This is a three-dimensional diagram of the unfolded and folded structure of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0046] Figure 12 This is a folded 3D diagram of the unfolded and folded structure of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0047] Figure 13 This is a three-dimensional diagram of the folded dorsal fin of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0048] Figure 14 This is a schematic diagram of the coordinated movement mode of the dorsal and caudal fins of the sailfish-like robot described in this invention.

[0049] Figure 15This is a schematic diagram of the second coordinated movement mode of the dorsal and caudal fins of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0050] Figure 16 This is a schematic diagram of the diving motion of the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins as described in this invention.

[0051] Figure 17 This is a schematic diagram of the upward movement of the sailfish-like robot propelled by the coordinated propulsion of its dorsal and caudal fins as described in this invention.

[0052] Figure 1-17 Names of components: A. Dorsal fin propulsion structure; B. Caudal fin propulsion structure; C. Front part of the fish; 1. Dorsal fin; 2. Rear bearing; 3. Dorsal fin rear cover; 4. Roller top cover; 5. Roller body; 6. Unfolding and folding structure; 7. Dorsal fin front cover; 8. Front bearing; 9. Transmission component; 10. Servo disc; 11. Waterproof servo on the back; 12. Motor; 13. Motor transmission rod; 14. Link 1; 15. Link 2; 16. Fixed rod; 17. Link 3; 18. Link 4; 19. Follower rod; 20. Nut slider; 21. Caudal fin; 22. Upper cavity of the rear joint; 23. Middle joint 24. Upper cavity; 25. Upper cavity of the front joint; 26. Waterproof servo motor at the tail; 27. Lower cavity of the front joint; 28. Tail bearing; 29. ​​Lower cavity of the middle joint; 30. Lower cavity of the rear joint; 31. Lower cavity of the front part of the fish; 32. Lithium battery; 33. Control board; 34. Gyroscope; 35. Upper cavity of the front part of the fish; 36. Front cover of the fish; 37. Infrared obstacle avoidance sensor; 38. Center of gravity adjustment device; 39. Camera; 40. Fish beak; 41. Center of gravity adjustment motor; 42. Slider baffle; 43. Counterweight box; 44. Nut; 45. Linear bearing; 46. Slider; 47. Optical axis. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0054] Combination Figure 1-17The present invention aims to provide a sailfish-inspired robot with coordinated dorsal and caudal fin propulsion and its coupling motion method. The robot is characterized by comprising a front section C, a dorsal fin propulsion structure A, and a caudal fin propulsion structure B. The front section C and the dorsal fin propulsion structure A, as well as the front section C and the caudal fin propulsion structure B, are secured with screws. Both the dorsal fin propulsion structure A and the caudal fin propulsion structure B have female waterproof aviation connectors, while the front section C has two male waterproof aviation connectors, corresponding to the dorsal fin propulsion structure A and the caudal fin propulsion structure B respectively. The use of waterproof aviation connectors ensures the independence of each component and the waterproofness of the control cable connections. The sailfish-inspired robot adopts a modular design, with each component, including the front section C, the dorsal fin propulsion structure A, and the caudal fin propulsion structure B, being an independent module. This allows for independent experimentation or rapid replacement in case of damage, facilitating robot maintenance, improving efficiency, and making it more suitable as an underwater research platform.

[0055] Combination Figure 3-4 This embodiment is a dorsal fin propulsion structure A of a sailfish-like robot with coordinated dorsal and tail fin propulsion. It mainly includes a dorsal fin 1, a rear bearing 2, a dorsal fin rear cover 3, a roller upper cover 4, a roller body 5, an unfolding and folding structure 6, a dorsal fin front cover 7, a front bearing 8, a transmission component 9, a servo disk 10, and a waterproof servo motor on the back 11. The roller body 5 is installed in the upper cavity 34 at the front of the fish and is connected to it by the front bearing 8 and the rear bearing 2. The unfolding and folding structure 6 is fixed to the side of the roller body 5 by screws. The roller cover 4 is fixed to the roller body 5 by screws and has a groove for the dorsal fin 1 and the unfolding and folding structure 6 to unfold. The dorsal fin 1 is installed on the unfolding and folding structure 6 by a combination of screws, nuts and washers. The waterproof back servo motor 11 is fixed in the upper cavity 34 at the front of the fish. The roller body 5 is connected to the output shaft of the waterproof back servo motor 11 through the transmission component 9 and the servo motor disk 10. The waterproof back servo motor 11 drives the roller body 5 to swing back and forth, so that the roller body 5 and the structure fixed to it have different swing amplitudes, and finally drive the dorsal fin to swing back and forth.

[0056] Combination Figure 5This embodiment describes the unfolding and folding structure 6 of a sailfish-like robot with coordinated dorsal and caudal fin propulsion. It mainly includes a motor 12, a motor drive rod 13, connecting rods 114 and 215, a fixed rod 16, connecting rods 317 and 418, a follower rod 19, and a nut and slider 20. The fixed rod 16 is fixed to the roller body 5 by a combination of screws, nuts, and washers, remaining stationary. All N connecting rods are connected to the fixed rod 16 and follower rod 19 by screws, forming a single-degree-of-freedom multi-link mechanism. Taking a connecting rod number N of 4 as an example, connecting rods 114, 215, 317, and 418 are all connected to the fixed rod 16 and follower rod 19 by screws, forming a single-degree-of-freedom multi-link mechanism. One end of the motor drive rod 13 is connected to the nut slider 20, and the other end is connected to one of the N parallel connecting rods; the motor 12 has a threaded rod that cooperates with the nut in the nut slider 20. When the motor 12 rotates, it drives the nut slider 20 to move forward and backward, which in turn drives the motor drive rod 13 to move, controlling the unfolding and folding of the unfolding and folding structure 6, so that the unfolding and folding structure 6 has different unfolding and folding degrees.

[0057] Combination Figure 6-7 This embodiment describes the tail fin propulsion structure B of a sailfish-like robot with coordinated dorsal and caudal fin propulsion. It mainly includes a tail fin 21, a rear joint upper cavity 22, a middle joint upper cavity 23, a front joint upper cavity 24, a tail waterproof servo 25, a front joint lower cavity 26, a tail bearing 27, a middle joint lower cavity 28, and a rear joint lower cavity 29. The tail fin propulsion structure B has M joints, where M is a natural number from 3 to 5. Each joint includes an upper cavity, a lower cavity, and a waterproof servo 25. The waterproof servo 25 is fixed in the lower cavity, and the upper and lower cavities are fixed together by screws. The bottom of the lower cavity is connected to the front joint via a bearing. The lower cavity of each joint is connected to the robot structure in front; the servo disk of the waterproof servo motor 25 is connected to the top of the upper cavity of the previous joint or the robot structure in front; taking the number of joints M as 3 as an example, the 3 joints are divided into front joint, middle joint and rear joint, and each joint's lower cavity has a slot as an outlet for the servo motor control line and to facilitate joint rotation; taking the middle joint as an example, the tail waterproof servo motor 25 is inserted into the lower cavity 28 of the middle joint and fixed with screws, and the upper cavity 23 of the middle joint is also fixed to the lower cavity 28 of the middle joint with screws, and the control line of the tail waterproof servo motor 25 extends from the reserved slot in the lower cavity 28 of the middle joint. In addition, the bottom end of the lower cavity 28 of the middle joint is equipped with a bearing and connected to the lower cavity 26 of the front joint; the servo disk of the tail waterproof servo motor 25 is connected to the top of the upper cavity 24 of the front joint with screws. When the servo disk of the tail waterproof servo motor 25 rotates, it will drive the middle joint and the structure behind it to rotate. The connections of the other anterior and posterior joints are similar, so they will not be described in detail here; the caudal fin 21 is connected to the posterior joint by screws.

[0058] Combination Figure 8-9 This embodiment describes the front part C of a sailfish-like robot propelled by coordinated dorsal and caudal fins. It includes a lower front cavity 30, a lithium battery 31, a control board 32, a gyroscope 33, an upper front cavity 34, a front cover 35, an infrared obstacle avoidance sensor 36, a center of gravity adjustment device 37, a camera 38, and a beak 39. The lithium battery 31 and counterweights are installed at the bottom of the lower front cavity 30 to lower the center of gravity. The gyroscope 33 is fixed to the control board 32 to obtain the robot fish's swimming posture. The infrared obstacle avoidance sensor 36 is installed in the front area of ​​the lower front cavity 30 to measure the distance to obstacles in real time. The camera 38 is installed in the front chamber of the lower front cavity 30, and two lighting devices are located on either side to provide illumination for the robot fish to swim in the dark. The beak is located at the very front of the robot fish and is connected to the lower front cavity 30 via a cross key. Its conical shape effectively reduces water resistance.

[0059] Combination Figure 10 This embodiment describes a center-of-gravity adjustment device 37 for a sailfish-inspired robot with coordinated dorsal and caudal fin propulsion. It mainly includes a center-of-gravity adjustment motor 40, a slider baffle 41, a counterweight box 42, a nut 43, linear bearings 44, a slider 45, and an optical axis 46. The center-of-gravity adjustment motor 40 is glued to the slider baffle 41. The nut 43 and two linear bearings 44 are installed in the slider 45. The slider 45 is mounted on the optical axis 46 via the linear bearings 44. A lead screw is connected to the output shaft of the center-of-gravity adjustment motor 40, forming a lead screw and nut pair with the nut 43 in the slider 45. A lead block is placed on the counterweight box 42 and fixed to the slider 45. When the center-of-gravity adjustment motor 40 rotates, it moves the slider 45, which in turn moves the counterweight box 42 and the lead block, ultimately achieving center-of-gravity adjustment.

[0060] Combination Figure 11-17 This embodiment describes a coupled motion method for a sailfish-inspired robot that uses its dorsal and caudal fins for coordinated propulsion, comprising the following processes:

[0061] The process of the dorsal fin unfolding and folding: combined with Figure 11-13 This embodiment describes a method for the dorsal fin deployment and folding motion of a sailfish-like robot propelled by coordinated dorsal and caudal fins, comprising the following processes:

[0062] When motor 12 rotates, nut slider 20 moves forward or backward, causing unfolding and folding structure 6 to unfold or fold, finally realizing the unfolding and folding of the dorsal fin of the sailfish robot.

[0063] The coordinated movement of the dorsal and caudal fins:

[0064] Combination Figure 14This embodiment is a sailfish-like robot with coordinated dorsal and caudal fin propulsion, which is a rapid forward movement mode. In this movement mode, the unfolding folding structure 6 is completely folded inside the robot body, so that the dorsal fin is folded up and the thrust is provided by the caudal fin propulsion structure B. Since the dorsal fin is folded up, the resistance when the robot moves forward is reduced. Combined with the robot's streamlined shape, the robot can achieve a high propulsion speed.

[0065] Combination Figure 15 This embodiment describes the second motion mode of the dorsal and caudal fin coordinated propulsion of the sailfish-like robot, which is a highly maneuverable motion. In this motion mode, the folding structure 6 unfolds, and the dorsal and caudal fins coordinate with each other. The coordination between the dorsal and caudal fins during dorsal fin deployment has the following two motion modes:

[0066] Movement Mode 2-1: When the sailfish-like robot turns left, its dorsal fin swings to the left side of its body and remains stationary, while its tail fin swings back and forth from side to side or slightly to the right. When the sailfish-like robot turns right, its dorsal fin swings to the right side of its body and remains stationary, while its tail fin swings back and forth from side to side or slightly to the left. In both cases, the tail fin provides propulsion, and the dorsal fin acts like a rudder, making the turning faster and the turning radius smaller. The waterproof servo motor 11 on the back drives the swing of the dorsal fin. The amplitude of the dorsal fin's swing is adjusted by the waterproof servo motor 11, so when the dorsal fin swings to the left or right side of its body and remains stationary, the dorsal fin has multiple different amplitudes corresponding to its stationary position. The unfolding and folding structure 6 adjusts the degree of unfolding and folding of the dorsal fin, so when the dorsal fin is unfolded, it has multiple different degrees of unfolding and folding. This coordinates with the tail fin, combining the two parameters of the stationary position of the dorsal fin and the degree of unfolding and folding to form more specific movement modes. Here, the left or right reciprocating swing refers to the position of the central axis being slightly to the left or right during the reciprocating swing.

[0067] Movement Mode 2-2: When the sailfish-like robot turns left, its dorsal fin swings back and forth to the left, and its tail fin swings back and forth to the left or right; when the sailfish-like robot turns right, its dorsal fin swings back and forth to the right, and its tail fin swings back and forth to the left or left. In both cases, the tail fin provides the main propulsion, while the dorsal fin provides a small amount of propulsion and also acts as a rudder, making the turning faster and the turning radius smaller. The waterproof servo motor 11 on the back drives the swing of the dorsal fin, and the swing amplitude of the dorsal fin can be adjusted by the waterproof servo motor 11, resulting in multiple different swing amplitudes. The unfolding and folding structure 6 adjusts the unfolding and folding degree of the dorsal fin, so when the dorsal fin is unfolded, it has multiple different unfolding and folding degrees. When there is a difference between the phase of the dorsal fin swing and the phase of the tail fin swing, different phase differences are formed. The dorsal fin and tail fin coordinate with each other, and the three parameters of the dorsal fin swing amplitude, unfolding and folding degree, and phase difference are combined to form more specific movement modes.

[0068] The process of three dives and ascents:

[0069] Combination Figure 16-17 This embodiment describes the diving and surfacing movements of a sailfish-inspired robot propelled by the coordinated dorsal and caudal fins. In this movement mode, combining the caudal fin propulsion structure B with the center of gravity adjustment device 37 results in the following two movement patterns:

[0070] Movement Mode 3-1: Inclined Diving and Ascending Movement. In this movement mode, for the diving movement, the center of gravity adjustment motor 40 rotates to move the counterweight box 42 forward, thereby causing the head of the robotic fish to droop. Then, the tail fin swings back and forth to make the robot swim forward and downward, finally completing the diving movement. For the ascending movement, the center of gravity adjustment motor 40 rotates to move the counterweight box 42 backward, thereby causing the head of the robotic fish to tilt upward. Then, the tail fin swings back and forth to make the robot swim forward and upward, finally completing the ascending and descending movement.

[0071] Motion Mode 3-2: Spiral Descent and Ascent Motion. In this motion mode, for the descent motion, the center of gravity adjustment motor 40 rotates, causing the counterweight box 42 to move forward, which in turn causes the head of the robotic fish to droop continuously. At the same time, the tail fin swings back and forth to the right or left, causing the robot to turn and finally complete the descent motion. The tail fin swings back and forth to the right for a counterclockwise spiral descent motion; the tail fin swings back and forth to the left for a clockwise spiral descent motion. For the ascent motion, the center of gravity adjustment motor 40 rotates, causing the counterweight box 42 to move backward, which in turn causes the head of the robotic fish to tilt upward. At the same time, the tail fin swings back and forth to the right or left, causing the robot to turn and finally complete the ascent motion. The tail fin swings back and forth to the right for a counterclockwise spiral ascent motion; the tail fin swings back and forth to the left for a clockwise spiral ascent motion.

[0072] Combination Figure 14-15 This embodiment describes a coupled motion method for a sailfish-inspired robot that uses its dorsal and caudal fins for coordinated propulsion, and includes the following specific processes:

[0073] For the second motion mode of the coordinated movement of the dorsal and caudal fins, namely high-mobility motion, if the angle of the swing of the roller 5 around its own axis is denoted as the swing amplitude angle, and α is taken as follows: α = 0, 0 < α < 30°, α = 30°, 30° < α < 60° and α = 60°, corresponding to the swing amplitude of the dorsal fin as stationary, small swing, medium swing, large swing and complete swing respectively; if the angle formed by the foremost link of the N parallel links of the unfolded and folded structure 6 and the central axis of the sailfish-like robot is taken as the standard, and denoted as the unfolding and folding angle, and β is taken as follows: β = 0, 0 < β < 30°, β = 30°, 30° < β < 60° and β = 60°, corresponding to the degree of unfolding of the dorsal fin 1 as completely folded, partially unfolded, half unfolded, mostly unfolded and completely unfolded respectively; the phase difference that exists when the dorsal and caudal fins swing is denoted as express, n = 0, 1, 2, ..., k-1, k ≥ 1 and l is divisible by 360°;

[0074] Regarding movement mode 2-1, when the dorsal fin is swung to the left or right side of the body and remains stationary, the dorsal fin has four different amplitudes corresponding to stationary positions: 0 < α < 30°, α = 30°, 30° < α < 60°, and α = 60°. When the dorsal fin is spread out, it has four different degrees of spread and folding: 0 < β < 30°, β = 30°, 30° < β < 60°, and β = 60°, which are partially spread, half-spread, mostly spread, and fully spread, respectively. These are coordinated with the caudal fin. Combining the two parameters of the stationary position of the dorsal fin and the degree of spread and folding, there are a total of 4 × 4 = 16 specific movement modes.

[0075] Regarding movement mode 2-2, when the dorsal fin swings, it has four different amplitudes: 0 < α < 30°, α = 30°, 30° < α < 60°, and α = 60°, corresponding to the swing amplitudes of stationary, small-amplitude, medium-amplitude, large-amplitude, and fully swinging, respectively. When the dorsal fin is spread, it has four different degrees of spread and folding: 0 < β < 30°, β = 30°, 30° < β < 60°, and β = 60°, corresponding to partial spread, half-spread, mostly spread, and fully spread, respectively. There are k different phase differences between the dorsal fin swing and the caudal fin swing. By coordinating the dorsal and caudal fins and combining the three parameters of swing amplitude, spread and folding degree, and phase difference, there are a total of 4 × 4 × k = 16·k specific movement modes. If l = 30°, then k = 12, meaning there are 4 × 4 × 12 = 192 specific movement modes.

Claims

1. A sailfish-inspired robot with coordinated propulsion via dorsal and caudal fins, characterized in that: It consists of the anterior part of the fish (C), the dorsal fin propulsion structure (A), and the caudal fin propulsion structure (B); The aforementioned front part (C) of the fish mainly includes the lower front cavity (30) and the upper front cavity (34), the front cover (35), and the beak (39) which is conical in shape and has the function of reducing water resistance; it also includes a lithium battery (31), a control board (32), and a center of gravity adjustment device (37) installed between the lower front cavity (30) and the upper front cavity (34); it also includes a gyroscope (33), an infrared obstacle avoidance sensor (36), a camera (38), and a lighting device installed between the lower front cavity (30) and the front cover (35); The aforementioned dorsal fin propulsion structure (A) mainly includes a dorsal fin (1), a roller cover (4), a roller body (5), an unfolding and folding structure (6), a dorsal waterproof servo (11), a transmission component (9), and a servo disc (10); wherein the roller body (5) is installed in the upper cavity (34) at the front of the fish and cooperates with it through the front bearing (8) and the rear bearing (2); the unfolding and folding structure (6) is fixed to the side of the roller body (5) by screws, and the roller cover (4) is fixed to the roller body (5) by screws, and has a groove for the dorsal fin. (1) The unfolded folding structure (6) unfolds; the dorsal fin (1) is installed on the unfolded folding structure (6) by a combination of screws, nuts and washers; the dorsal waterproof servo (11) is fixed in the upper cavity (34) at the front of the fish, and the roller (5) is connected to the output shaft of the dorsal waterproof servo (11) through the transmission component (9) and the servo disk (10). The dorsal waterproof servo (11) drives the roller (5) to swing back and forth, so that the roller (5) and the structure fixed thereto have different swing amplitudes, and finally drives the dorsal fin to swing back and forth. The above-mentioned unfolding and folding structure (6) mainly includes a motor (12), a motor drive rod (13), a nut slider (20), a fixed rod (16), a follower rod (19), and N parallel connecting rods, where N is a natural number from 4 to 8. The fixed rod (16) is fixed to the roller body (5) by a combination of screws, nuts and washers and remains stationary. The N connecting rods are all connected to the fixed rod (16) and the follower rod (19) by screws to form a multi-link mechanism with a single degree of freedom. One end of the motor drive rod (13) is connected to the nut slider (20), and the other end is connected to one of the N parallel connecting rods. The motor (12) has a threaded rod that cooperates with the nut in the nut slider (20). When the motor (12) rotates, it drives the nut slider (20) to move forward and backward, which in turn drives the motor drive rod (13) to move, controlling the unfolding and folding of the unfolding and folding structure (6) so that the unfolding and folding structure (6) has different degrees of unfolding and folding. The aforementioned tail fin propulsion structure (B) has a total of M joints, where M is a natural number from 3 to 5. Each joint includes an upper joint cavity, a lower joint cavity, and a waterproof joint servo (25). The waterproof joint servo (25) is fixed in the lower joint cavity, and the upper joint cavity and the lower joint cavity are fixed together by screws. The bottom end of the lower joint cavity is connected to the lower joint cavity of the previous joint or the robot structure in front of it through a bearing. The servo disk of the waterproof joint servo (25) is connected to the top of the upper joint cavity of the previous joint or the robot structure in front of it. The tail fin (21) is connected to the last joint by screws.

2. The sailfish-like robot with coordinated propulsion of the dorsal and caudal fins according to claim 1, characterized in that: The aforementioned center of gravity adjustment device (37) mainly includes a center of gravity adjustment motor (40), a slider (45), a nut (43), a linear bearing (44), an optical shaft (46), a lead screw, and a counterweight box (42). The nut (43) and linear bearing (44) are installed in the slider (45); the slider (45) is installed on the optical shaft (46) through the linear bearing (44); the lead screw is connected to the output shaft of the center of gravity adjustment motor (40), and the lead screw and the nut (43) in the slider (45) form a lead screw and nut pair; the counterweight box (42) is fixed on the slider (45).

3. The sailfish-like robot with coordinated propulsion of the dorsal and caudal fins according to claim 1, characterized in that: A lithium battery (31) and a counterweight are installed in the bottom area of ​​the lower front cavity (30) of the fish to lower the center of gravity; a gyroscope (33) is fixed on the control board (32) to obtain the posture of the robotic fish when it swims; an infrared obstacle avoidance sensor (36) is installed in the front area of ​​the lower front cavity (30) of the fish to measure the distance to obstacles in real time; a camera (38) is installed in the front side chamber of the lower front cavity (30) of the fish, and two lighting devices are located on both sides to provide illumination for the robotic fish.

4. The sailfish-like robot with coordinated propulsion of the dorsal and caudal fins according to claim 1, characterized in that: The dorsal fin propulsion structure and the caudal fin propulsion structure both have female waterproof aviation plugs, while the front part of the fish has two male waterproof aviation plugs, with the female and male plugs corresponding to each other.

5. The coupled motion method for a sailfish-like robot with coordinated propulsion of the dorsal and caudal fins according to claim 2, characterized in that... Includes the following processes: (a) Dorsal fin unfolding and folding motion process: When the motor (12) rotates, the nut slider (20) moves forward or backward, driving the unfolding and folding structure (6) to unfold or fold; (II) The coordinated movement of the dorsal and caudal fins: The first motion mode is a fast forward motion. In this motion mode, the unfolded folding structure (6) is completely folded inside the robot body, so that the dorsal fin is folded up and the tail fin propulsion structure (B) provides thrust. Since the dorsal fin is folded up, the resistance when the robot moves forward is reduced. Combined with the robot's streamlined shape, the robot can achieve a high propulsion speed. The second movement mode is a high-mobility movement. In this movement mode, the folding structure (6) unfolds, and the dorsal fin and caudal fin coordinate with each other. The coordination between the dorsal fin and caudal fin when the dorsal fin unfolds has the following two movement modes: Movement mode 2-1: When the sailfish-like robot turns left, the dorsal fin swings to the left side of the body and remains stationary, while the tail fin swings back and forth or to the right side; when the sailfish-like robot turns right, the dorsal fin swings to the right side of the body and remains stationary, while the tail fin swings back and forth or to the left side; when the sailfish-like robot turns left or right, the tail fin provides propulsion, and the dorsal fin acts like a rudder, making the turning faster and the turning radius smaller; the waterproof back servo (11) drives the swing of the dorsal fin, and the swing amplitude of the dorsal fin is adjusted by the waterproof back servo (11), so when the dorsal fin swings to the left or right side of the body and remains stationary, the dorsal fin has a variety of different amplitudes corresponding to the stationary position; the unfolding and folding structure (6) adjusts the unfolding and folding degree of the dorsal fin, so when the dorsal fin is unfolded, the dorsal fin has a variety of different unfolding and folding degrees; this is coordinated with the tail fin, and the two parameters of the stationary position of the dorsal fin and the unfolding and folding degree are combined to form more specific movement modes; here, the back-and-forth swing to the left or right refers to the position of the central axis to the left or right during the back-and-forth swing; Movement mode 2-2: When the sailfish-like robot turns left, the dorsal fin swings back and forth to the left, and the tail fin swings back and forth to the left or to the right; when the sailfish-like robot turns right, the dorsal fin swings back and forth to the right, and the tail fin swings back and forth to the left or to the left; when the sailfish-like robot turns left or right, the tail fin provides the main propulsion, and the dorsal fin provides a small amount of propulsion and also has a certain rudder-like function, making the turning faster and the turning radius smaller; the waterproof back servo (11) drives the swing of the dorsal fin, and the swing amplitude of the dorsal fin is adjusted by the waterproof back servo (11), and the dorsal fin has a variety of different swing amplitudes; the unfolding and folding structure (6) adjusts the unfolding and folding degree of the dorsal fin, so when the dorsal fin is unfolded, the dorsal fin has a variety of different unfolding and folding degrees; when there is a difference between the phase of the dorsal fin swing and the phase of the tail fin swing, different phase differences are formed; the dorsal fin and the tail fin coordinate with each other, and the three parameters of the dorsal fin swing amplitude, unfolding and folding degree and phase difference are arranged and combined to form more specific movement modes; (III) The process of diving and surfacing: In this motion mode, the combination of the caudal fin propulsion structure (B) and the center of gravity adjustment device (37) results in the following two motion modes: Movement mode 3-1: Oblique diving and surfacing movement. In this movement mode, for diving, the center of gravity adjustment motor (40) rotates to move the counterweight box (42) forward, thereby causing the head of the robot fish to droop. Then, the tail fin swings back and forth to make the robot swim forward and downward, and finally completes the diving movement. For surfacing, the center of gravity adjustment motor (40) rotates to move the counterweight box (42) backward, thereby causing the head of the robot fish to tilt upward. Then, the tail fin swings back and forth to make the robot swim forward and upward, and finally completes the diving and surfacing movement. Movement mode 3-2: Spiral diving and surfacing movement. In this movement mode, for diving, the center of gravity adjustment motor (40) rotates to move the counterweight box (42) forward, thereby causing the head of the robotic fish to droop continuously. At the same time, the tail fin swings back and forth to the right or left to turn the robot and finally complete the diving movement. The tail fin swings back and forth to the right for counterclockwise spiral diving; the tail fin swings back and forth to the left for clockwise spiral diving. For surfacing, the center of gravity adjustment motor (40) rotates to move the counterweight box (42) backward, thereby causing the head of the robotic fish to tilt upward. At the same time, the tail fin swings back and forth to the right or left to turn the robot and finally complete the surfacing movement. The tail fin swings back and forth to the right for counterclockwise spiral surfacing; the tail fin swings back and forth to the left for clockwise spiral surfacing.

6. The coupled motion method for the sailfish-like robot with coordinated propulsion of the dorsal and caudal fins according to claim 5, characterized in that... Includes the following processes: For the second motion mode of the coordinated movement of the dorsal and caudal fins, namely high-mobility motion, if the angle of the swing of the roller (5) around its own axis is denoted as the swing amplitude angle, then... express, The range of values ​​is as follows: , , , or The swing amplitudes corresponding to the dorsal fin are categorized as stationary, small swing, medium swing, large swing, and full swing; if the angle formed by the foremost link among the N parallel links of the unfolded folding structure (6) and the central axis of the sailfish-like robot is used as the standard, it is denoted as the unfolding folding angle. express, The range of values ​​is as follows: , , , or The degree of deployment of the dorsal fin (1) is divided into fully folded, partially deployed, semi-deployed, mostly deployed, and fully deployed; the phase difference between the dorsal fin and caudal fin during their swing is represented by... express, ; Regarding movement mode 2-1, when the dorsal fin swings to the left or right side of the body and remains stationary, the dorsal fin has four different amplitudes corresponding to stationary positions, namely... , , or ; When the dorsal fin is spread, it has four different degrees of folding and unfolding. , , or These are categorized as partially unfolded, half-unfolded, mostly unfolded, and fully unfolded, all coordinated with the caudal fin. These combinations are derived from the parameters of the dorsal fin's stationary position and the degree of unfolding / folding, resulting in a total of [number missing]. A specific type of exercise; Regarding movement mode 2-2, when the dorsal fin swings, it exhibits four different amplitudes, namely... , , or The amplitude of the dorsal fin's oscillation is categorized into stationary, small-amplitude, medium-amplitude, large-amplitude, and fully extended oscillation. When the dorsal fin is extended, it exhibits four different degrees of extension and folding. , , or These are represented by partially deployed, half-deployed, mostly deployed, and fully deployed, respectively; the different phase differences between the dorsal fin oscillation and the caudal fin oscillation are: There are 1; the dorsal and caudal fins coordinate with each other, and the three parameters of dorsal fin swing amplitude, unfolding and folding degree and phase difference are combined to form a total of 1. A specific type of exercise.

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