Bionic hairtail robot and method based on double-coupled motion of dorsal fin and fish body

Abstract

A bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body, belonging to the field of robot technology applications. The multi-joint bionic hairtail robot includes five major parts: a hairtail head, N body units, a hairtail tail, a torsion spring, and a dorsal fin. Among them, there is a center-of-gravity adjustment mechanism inside the hairtail head, which can realize the attitude adjustment of pitching up and down. It can move forward through the independent undulation of the dorsal fin and the reaction force generated by the swinging of each body unit, greatly simulating the real movement mode of hairtail in reality. While studying the realization of mobility and stability, the propulsion efficiency is improved. It has important research significance and application value in the fields of underwater pipeline quality inspection, water quality inspection, etc.

Description

Technical Field

[0001] The invention belongs to the field of robot technology applications, and specifically relates to the mechanical structure and motion mode of a multi-joint bionic hairtail robot that moves based on the coupling of body BCF propulsion and dorsal fin sinusoidal motion. The invention can meet the functions of water quality and leakage point detection in underwater pipelines, and can also be applied to observe the activities of wild organisms in the natural water environment. Background Art

[0002] Bionic robotic fish imitate the shape and motion patterns of fish in order to achieve the characteristics of efficient and fast fish motion, getting rid of the disadvantages of traditional propeller-driven underwater robots such as high noise, low efficiency, and high energy consumption. It has been a hot topic in the research of underwater thrusters in recent years. It is estimated that 85% of fish use the Body and / or caudal fin propulsion (BCF) mode as the conventional propulsion mode. The BCF mode of swimming is continuous, fast, and efficient. BCF propulsion forms thrust through the telescopic undulation of the trunk and the swinging of the caudal fin, with fast swimming speed, high efficiency, and high quick-start performance, being suitable for long-time, long-distance high-speed swimming or occasions that require instantaneous acceleration or turning. The BCF mode is further divided into the anguilliform mode, the carangiform mode, the thunniform mode, the ostraciiform mode, and the balistiform mode, and these five modes gradually transition from undulation to swinging. Currently, the research on bionic fish in the anguilliform mode mainly focuses on eels, and there is relatively little research on bionic hairtail robots. Compared with eels, eels swim only by the undulation of the body, while hairtail adds the undulation of the dorsal fin on the basis of body undulation.

[0003] Compared with some robots with similar motion structures, the "Underwater Multi-Degree-of-Freedom Eel Robot" developed by Feng Yikun (CN201510700641.2) designed a cross structure. Inside the upper and lower frames of a single cross structure, a servo motor is installed respectively. The two servo motors cooperate with each other to drive the three-dimensional rotation of the cross structure. A single cross structure serves as a joint of the robot and forms the body of the robot. The servo motors drive the rotation of each joint through gears to achieve the movement of the robot, solving the problems of complex structure, low degree of freedom, and high cost of similar robots; the "Multi-Segment Underactuated Bionic Eel Robot" developed by South China University of Technology (CN202210243311.5) studied the problems of low energy conversion efficiency in multi-motor control and too long length of the soft body used in similar robots, and limited control of the eel body movement by the driving section, making it difficult to simulate the waveform transmission during eel swimming. It invented a new type of bionic eel robot, including at least two traction sections and at least two follower sections. The traction sections include a first traction section and a second traction section, and the follower sections include a middle follower section and a tail follower section. The first traction section, the middle follower section, the second traction section, and the tail follower section are connected in sequence. Through the multi-segment underactuated structure of two traction sections plus two follower sections, it can better simulate the waveform transmission and swimming gait of real eels; the "Underwater Multi-Degree-of-Freedom Eel Robot" developed by Chen Jiang (CN201922376598.5) aimed at the problem that adjacent joints of existing eel simulation robots are mostly connected by wires, and the wires are easily worn after long-term twisting, and it is easy to leak electricity and short-circuit when moving underwater, causing damage. It designed a new type of underwater multi-degree-of-freedom eel robot, which sequentially includes a head-end module, a first node module, a second node module, and a tail-end module. The first node module and the second node module are arranged between the head-end module and the tail-end module. The first node module is hinged on the head-end module and the second node module, the second node module is hinged on the first node module, and the tail-end module is hinged on the first node module, but it is propelled by a propeller; the "High-Speed Soft Bionic Hairtail Robot Driven by Chemical Exothermic Reaction" developed by Zhejiang University (CN202010589341.2) developed a soft robot in view of the disadvantages of traditional rigid robots such as large volume, high weight, high noise, and poor environmental adaptability. It includes a fish head module, a fish body module, and a fish tail module. The fish head module includes a fish head shell, and a rigid exothermic reaction chamber, a combustible agent storage unit, an oxidizer storage unit, and an exothermic reaction excitation device are arranged inside the fish head shell. A rigid push plate is slidably fitted inside the rigid exothermic reaction chamber. The fish body module includes a flexible fishbone, a constraint component, and a flexible fish skin. The fish tail module includes a fish tail fixing block. Through the combined action of the transient velocity phenomenon and the post-buckling phenomenon of the plate material, the rapid driving of the soft robot can be realized.

[0004] Compared with the above cases, on each body unit of the present invention, a servo motor is used to drive the dorsal fin fixed on the torsion spring to swing, and another servo motor is used to drive the fish body to achieve sinusoidal fluctuations, finally realizing the fabrication of a bionic hairtail robot based on the dual-coupled movement of the dorsal fin and the fish body. With a relatively low cost, a clever structural design, and reasonable and effective waterproof measures, it achieves the experimental results of the same project. Such a multi-joint bionic hairtail robot and method have not been specifically studied in China. Summary of the Invention

[0005] The purpose of the present invention is to utilize the shape characteristics and swimming characteristics of the hairtail, through processes such as modeling and simulation, 3D printing, single-chip microcomputer control, and underwater testing, to realize the fabrication of a multi-joint bionic hairtail robot that can meet functions such as underwater pipeline quality inspection and target recognition, and at the same time has the dual-coupled movement of the dorsal fin and the fish body, greatly simulating the real movement mode of the hairtail in reality, and finally effectively reducing the need for manual underwater operations.

[0006] A bionic hairtail robot based on the dual-coupled movement of the dorsal fin and the fish body, characterized in that:

[0007] It includes a hairtail head, N body units, and a hairtail tail;

[0008] The above-mentioned hairtail head is composed of an upper head shell, a lower head shell, and a system board, a model airplane battery, a visual recognition module, and a center-of-gravity adjustment mechanism installed in the lower head shell; the center-of-gravity adjustment mechanism is composed of a fish-head built-in motor, a fish-head moving configuration block, a guide rod, and a screw rod; wherein the screw rod is installed on the output shaft of the fish-head built-in motor, and the fish-head built-in motor and the guide rod are fixed in the head shell; the fish-head moving configuration block is installed on the screw rod and the guide rod, and the threaded hole of the fish-head moving configuration block is screwed with the screw rod;

[0009] The above-mentioned body unit includes a left housing of the body unit and a right housing of the body unit; it also includes a first servo of the body unit, a first steering wheel of the body unit servo, a first output shaft of the body unit, a first bearing of the body unit, a second servo of the body unit, a second steering wheel of the body unit servo, a second output shaft of the body unit, a second bearing of the body unit, a large gear of the body unit, and a small gear of the body unit, which are installed inside the right housing of the body unit; among them, after the first output shaft of the body unit is fitted with the first bearing of the body unit, it is fixed to the output rotating shaft of the first servo of the body unit through the steering wheel of the first servo of the body unit, and the first servo of the body unit is fixed at the rear inside of the right housing of the body unit; the large gear of the body unit is spaced from the first bearing of the body unit and is fitted with the first output shaft and fixed in the middle of the right housing of the body unit, and meshes with the small gear of the body unit, and the small gear of the body unit extends out of the body unit; after the second output shaft of the body unit is fitted with the second bearing of the body unit, it is fixed to the output rotating shaft of the second servo of the body unit through the steering wheel of the second servo of the body unit, and the second servo of the body unit is fixed at the front inside of the right housing of the body unit; the end of the second output shaft of the body unit extends out of the housing of the body unit;

[0010] The tail of the hairtail consists of a left housing of the fish tail, a right housing of the fish tail, a first servo of the fish tail, a first steering wheel of the fish tail servo, a first output shaft of the fish tail, a first bearing of the fish tail, a second servo of the fish tail, a second steering wheel of the fish tail servo, a second output shaft of the fish tail, a second bearing of the fish tail, a large gear of the fish tail, a small gear of the fish tail, and a thin sheet at the end of the fish tail; among them, after the first output shaft of the fish tail is fitted with the first bearing of the fish tail, it is fixed to the output rotating shaft of the first servo of the fish tail through the steering wheel of the first servo of the fish tail, and the first servo of the fish tail is fixed at the rear inside of the right housing of the fish tail; the large gear of the body unit is spaced from the first bearing of the fish tail and is fitted with the first output shaft and fixed in the middle of the right housing of the fish tail, and meshes with the small gear of the fish tail, and the small gear of the fish tail extends out of the tail of the hairtail; after the second output shaft of the fish tail is fitted with the second bearing of the fish tail, it is fixed to the output rotating shaft of the second servo of the fish tail through the steering wheel of the second servo of the fish tail, and the second servo of the fish tail is fixed at the front inside of the right housing of the fish tail; the end of the second output shaft of the fish tail extends out of the housing of the fish tail;

[0011] The lower housing of the above-mentioned head is connected to the second output shaft of the first adjacent body unit. After the left housing of the body unit and the right housing of the body unit are buckled together, they are jointly connected to the second output shaft of the adjacent body unit behind them; the body unit close to the tail of the hairtail is connected to the second output shaft of the fish tail; the multi-joint bionic hairtail robot also includes a torsion spring and a dorsal fin; the torsion spring sequentially passes through the through holes of the body unit, and the above-mentioned small gear of the body unit and the small gear of the fish tail are sequentially sleeved on the torsion spring and fixedly connected to the torsion spring; the dorsal fin is fixedly connected to the torsion spring and twists with it to achieve undulation.

[0012] The motion method of the above-mentioned bionic hairtail robot based on the dual-coupled motion of the dorsal fin and the fish body is characterized by including the following processes:

[0013] First, the symmetry line of the vertical symmetry plane of the body of the multi-joint bionic hairtail robot is called the body center line. When the body center line is in the horizontal plane, the posture in which the dorsal fin (Q1) of the multi-joint bionic hairtail robot is directly above the horizontal plane is called the vertical posture. The angle between each body unit and the adjacent body unit in the direction close to the head of the hairtail is called the forward offset angle, and the angle between the adjacent body unit in the direction away from the head of the hairtail is called the backward offset angle. It is positive when it is left-offset relative to the forward direction and negative when it is right-offset relative to the moving direction. Among them, the positive direction of the body center line is from the tail (W1) of the hairtail to the head (T1) of the hairtail. When the head (T1) of the hairtail deviates above the horizontal plane, the angle between the positive direction of the body center line and the horizontal plane is called the elevation angle. When the head (T1) of the hairtail deviates below the horizontal plane, the angle between the positive direction of the body center line and the horizontal plane is called the depression angle.

[0014] Overall vertical forward swimming: All body units are driven by the first servo of the subsequent body unit and the first servo of the fish tail. Their swing frequencies and swing amplitudes are exactly the same, but there are fixed and equal phase differences, so as to achieve a standard sine wave-like motion.

[0015] A flexible dorsal fin is adopted. When all body units swing left and right, the first servo of all body units and the first servo of the fish tail jointly drive the small gear of the body unit and the small gear of the fish tail through the large gear of the body unit and the large gear of the fish tail, driving the torsion spring to perform torsion with the same frequency and amplitude but with a phase difference, so as to drive the dorsal fin to achieve an independent sine wave fluctuation relative to the body unit.

[0016] The vertical cross-section of each body unit and the flexible surface of the dorsal fin simultaneously generate a backward acting force on the water, and the water generates a forward thrust on the multi-joint bionic hairtail robot, realizing the overall forward movement.

[0017] Overall vertical turning swimming to the left or right: Several body units close to the head of the hairtail remain relatively stationary and have a fixed forward offset angle at the same time; the swing frequencies of several body units close to the tail of the hairtail are exactly the same, but there is a linearly increasing relationship in the swing amplitude, and there is also a fixed phase difference at the same time.

[0018] A flexible dorsal fin is adopted. When all body units swing left and right, the first servo of all body units and the first servo of the fish tail jointly drive the small gear of the body unit and the small gear of the fish tail through the large gear of the body unit and the large gear of the fish tail, driving the torsion spring to perform torsion with the same frequency and amplitude but with a phase difference, so as to drive the dorsal fin to achieve an independent sine wave fluctuation relative to the body unit.

[0019] When the forward offset angle is positive, the thrust of the water on the right side is greater than that on the left side, and it is subjected to an unbalanced force, that is, a left-turn torque, realizing a left turn.

[0020] When the forward offset angle is negative, the thrust of water on the left side is greater than that on the right side, and it is subjected to an unbalanced force, that is, a right-turning torque, to achieve a right turn.

[0021] Overall vertical up-and-down pitching conversion: A center-of-gravity adjustment mechanism is configured at the head of the hairtail; four configuration blocks are configured inside each of the subsequent N body units and the hairtail. The four configuration blocks are divided into two each in the up-and-down and left-right directions and are symmetrically arranged. When installing, by adjusting the positions of the configuration blocks, the center of gravity and the center of buoyancy of each body unit or the hairtail are made to coincide with each other; after ensuring that the partial centers of gravity and the centers of buoyancy of the N body units and the hairtail coincide, the pitching conversion is achieved through the relevant movement of the center-of-gravity adjustment mechanism at the head of the hairtail.

[0022] The motion method of the bionic hairtail robot based on the double-coupled motion of the dorsal fin and the fish body is characterized by including the following process:

[0023] The pitching conversion is achieved through the relevant movement of the center-of-gravity adjustment mechanism at the head of the hairtail, and the specific implementation is as follows:

[0024] In the initial state, the fish head moving configuration block is located at the middle position of the guide rod; when the upward-looking posture is to be achieved, the built-in motor of the fish head drives the fish head moving configuration block to move forward or backward through the rotation of the screw; during the entire movement process of the fish head moving configuration block, the center of gravity of the fish head gradually moves forward or backward, and a torque is formed between gravity and buoyancy. When the target upward-looking posture is reached, the degree of this upward look, that is, the magnitude of the elevation angle, is proportional to the magnitude of the forward or backward displacement of the fish head moving configuration block.

[0025] The present invention has the following advantages compared with the prior art:

[0026] 1. Compared with the previous bionic fish with fewer joints, the production of a multi-joint bionic hairtail robot is realized.

[0027] 2. Two servos are provided for each body unit to realize the double-coupled motion of the dorsal fin and the fish body of a multi-joint bionic hairtail robot.

[0028] 3. The structure of the present invention is simple, the design is ingenious, the motion principle is clear, and it is convenient to implement.

[0029] 4. The present invention more realistically realizes the swimming process of the hairtail in the deep sea, can realize swimming with high maneuverability in water, and has the characteristics of high efficiency, low energy consumption, and strong environmental concealment.

[0030] 5. A center-of-gravity adjustment mechanism is installed inside the fish head, which can realize the conversion of postures including up-and-down pitching, and realize the high-maneuverability swimming and posture adjustment of the multi-joint bionic hairtail robot in water.

[0031] The described multi-joint bionic hairtail robot is characterized in that it mainly consists of a hairtail head, N identical body units and a hairtail tail. The main body is composed of multiple similar body units; plus a torsion spring and a flexible dorsal fin to assist in movement. Its structure is simple, the design is ingenious, and the movement principle is clear, which is beneficial to the movement stability of the robot. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the overall oblique view of the bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body according to the present invention;

[0033] Figure 2 is the schematic diagram of the module decomposition of the bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body according to the present invention;

[0034] Figure 3 is the schematic diagram of the structural decomposition of the hairtail head of the bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body according to the present invention;

[0035] Figure 4 is the schematic diagram of the structural decomposition of the body unit of the bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body according to the present invention;

[0036] Figure 5 is the schematic diagram of the structural decomposition of the hairtail tail of the bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body according to the present invention;

[0037] Figure 6 is the schematic diagram of the movement of the bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body swimming vertically in water;

[0038] Figure 7 is the schematic diagram of the movement of the bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body achieving up and down pitching in water;

[0039] Figure 8 is the schematic diagram of the movement of the bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body turning in an underwater pipeline and identifying a target object;

[0040] Figure 1-8Name of the winning number: hairtail head T1; body unit Z1; body unit Z2; body unit Z3; body unit Z4; body unit Z5; hairtail tail W1; torsion spring N1; dorsal fin Q1; upper head shell A1; fish head moving configuration block A2; fish head built-in motor A3; fish head motor fixing box A4; model aircraft battery A5; fish head sealing ring A6; lower head shell A7; visual recognition module A8; system board A9; guide rod A10; screw A11; right body unit shell B1; body unit first servo B2; body unit first servo steering wheel B3; body unit first output shaft B4; body unit first bearing B5; body unit large gear B6; body unit left housing B7; body unit second bearing B8; body unit second output shaft B9; body unit second servo steering wheel B10; body unit second servo B11; body unit pinion B12; fishtail right housing C1; fishtail end sheet C2; fishtail first servo C3; fishtail first servo steering wheel C4; fishtail first output shaft C5; fishtail first bearing C6; fishtail large gear C7; fishtail left housing C8; fishtail second bearing C9; fishtail second output shaft C10; fishtail second servo steering wheel C11; fishtail second servo C12; fishtail pinion C13. Among them, X, Y, and Z are corresponding three-dimensional space coordinate systems. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0042] Combination Figure 1-8 The present embodiment is a bionic hairtail robot and method based on the dual coupling motion of dorsal fin and fish body, comprising a hairtail head T1; a body unit Z1; a body unit Z2; a body unit Z3; a body unit Z4; a body unit Z5; a hairtail tail W1; a torsion spring N1; a dorsal fin Q1; an upper head shell A1; a fish head moving configuration block A2; a fish head built-in motor A3; a fish head motor fixing box A4; a model aircraft battery A5; a fish head sealing ring A6; a lower head shell A7; a visual recognition module A8; a system board A9; a guide rod A10; a screw rod A11; a right body unit shell B1; a first steering gear B2 of the body unit; a steering wheel B3 of the first steering gear of the body unit; a steering wheel B4 of the first steering gear of the body unit; a steering wheel B5 of the first steering gear of the body unit; a steering wheel B6 of the first steering gear of the body unit; a steering wheel B7 of the first steering gear of the body unit; a steering wheel B8 of the first steering gear of the body unit; a steering wheel B9 of the first steering gear of the body unit; a steering wheel B1 of the first steering gear of the body unit; a steering wheel B1 of the first steering gear of the body unit; a steering wheel B2 of the first steering gear of the body unit; a steering wheel B3 ...1 of the first steering gear of the body unit; a steering wheel B1 of the first steering gear of the body unit; a steering wheel B1 of the first steering gear of the body unit; a steering wheel B1 of the first steering gear of the body unit; a steering wheel An output shaft B4; a first bearing B5 of the body unit; a large gear B6 of the body unit; a left housing B7 of the body unit; a second bearing B8 of the body unit; a second output shaft B9 of the body unit; a second servo steering wheel B10 of the body unit; a second servo B11 of the body unit; a small gear B12 of the body unit; a right housing C1 of the fishtail; a thin sheet C2 at the end of the fishtail; a first servo C3 of the fishtail; a first servo steering wheel C4 of the fishtail; a first output shaft C5 of the fishtail; a first bearing C6 of the fishtail; a large gear C7 of the fishtail; a left housing C8 of the fishtail; a second bearing C9 of the fishtail; a second output shaft C10 of the fishtail; a second servo steering wheel C11 of the fishtail; a second servo C12 of the fishtail; a small gear C13 of the fishtail.

[0043] Combined with Figures 1-5 , this embodiment is a bionic hairtail robot and method based on the dual-coupled motion of the dorsal fin and the fish body, including the hairtail head T1; the body unit Z1; the body unit Z2; the body unit Z3; the body unit Z4; the body unit Z5; the hairtail tail W1; the torsion spring N1; the dorsal fin Q1. The upper surface concave hole and the lower surface concave hole at the rear connection of the lower housing A7 of the head are respectively matched with the upper output shaft of the front end of the body unit Z1 and the convex platform at the lower connection, presenting a connection method of buckling two by two. Figure 2 Only the body units Z1-Z5 of the multi-joint bionic hairtail robot are given in [reference]. In theory, there are Z1-ZN. So far, Figure 2 the outer shapes of Z1-Z5 are exactly the same, and the connection methods between Z1-Z5 and between them and W1 are also the same as the connection method between the lower housing A7 of the head and the body unit Z1. The torsion spring N1 is fixedly connected to the body unit small gear B12 on the body units Z1-Z5 and the fish tail small gear C13 on the hairtail tail W1, and successively passes through the body units Z1-Z5 and the upper through hole of the outer shell of the hairtail tail W1. The dorsal fin Q1 is fixedly connected to the torsion spring N1. The body unit small gears B12 and the fish tail small gears C13 on the body units Z1-Z5 rotate with the same frequency and amplitude but with a phase difference, thereby driving corresponding points on the torsion spring N1 to generate a torsion with the same frequency and amplitude but with a phase difference, thereby realizing the sinusoidal fluctuation of the dorsal fin Q1.

[0044] Combined with Figure 6 , this embodiment is a bionic hairtail robot and method based on the dual-coupled motion of the dorsal fin and the fish body. The swinging frequencies and amplitudes of all body units are exactly the same but there are fixed and equal phase differences, so as to achieve a standard sinusoidal wave motion; a flexible dorsal fin Q1 is adopted. When all body units swing left and right, all body unit first servos and the fish tail first servo jointly drive the torsion spring to twist with a phase difference through the body unit large gear and the fish tail large gear, thereby driving the dorsal fin N1 to realize sinusoidal fluctuation. So far, the vertical cross-sections of each body unit and the flexible surface of the dorsal fin Q1 simultaneously generate a backward acting force on the water, and the water generates a forward thrust on the multi-joint bionic hairtail robot. Realize the overall forward movement.

[0045] Combined with Figure 7, this embodiment is a bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body. There is a center-of-gravity adjustment mechanism in the head of the hairtail. During vertical swimming, the motor A3 inside the fish head rotates the screw A11, and the fish head moving configuration block moves forward or backward, thereby adjusting the center of gravity to move forward or backward. Since the center of gravity and the center of buoyancy are not on the same vertical line, a deflection moment will be generated, so that the body center line of the multi-joint bionic hairtail robot forms a certain pitch angle with the horizontal plane, realizing the attitude adjustment of pitching up and down.

[0046] Combined with Figure 8 , this embodiment is a bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body. By means of the reciprocating cyclic movement of each body unit, the multi-joint bionic hairtail robot can simulate a sinusoidal wave reciprocating swing underwater. By separately changing one or simultaneously changing multiple forward offset angles of the body units to push the water flow, the movement thrust can be increased, the movement speed can be improved, the turning radius can be reduced at the same time, and the turning efficiency and movement maneuverability can be improved.

[0047] Combined with Figure 8 , this embodiment is a bionic hairtail robot and method based on the dual-coupled movement of the dorsal fin and the fish body. The angle between each body unit and the adjacent body unit in the direction close to the fish head is called the forward offset angle, and the angle between the body unit and the adjacent body unit in the direction away from the fish head is called the backward offset angle. It is positive for left offset relative to the forward direction and negative for right offset relative to the movement direction. A number of joints close to the fish head remain relatively stationary and have a fixed forward offset angle at the same time. The swing frequencies of a number of joints close to the fish tail are exactly the same, but there is a linearly increasing relationship in the swing amplitude, and there is a fixed phase difference at the same time. A flexible dorsal fin Q1 is adopted. When all body units swing left and right, the first servo motors of all body units and the first servo motor of the fish tail drive the torsion spring to twist with a phase difference through the large gears of the body units and the large gear of the fish tail, thereby driving the dorsal fin N1 to achieve sinusoidal fluctuations. The vertical cross-sections of each body unit and the flexible surface of the dorsal fin Q1 simultaneously generate a backward acting force on the water, and the water generates a forward thrust on the multi-joint bionic hairtail robot. The overall forward movement is realized. When the forward offset angle is positive, the thrust on the right side by the water is greater than that on the left side, generating an unbalanced force, that is, a left-turn torque, to realize the overall left-turn movement.

Claims

1. A bionic hairtail robot based on the dual-coupled motion of the dorsal fin and the fish body, characterized in that: It includes a hairtail head, N body units, and a hairtail tail; The above-mentioned hairtail head consists of an upper head shell (A1), a lower head shell (A7), and a system board (A9), a model aircraft battery (A5), a visual recognition module (A8), and a center of gravity adjustment mechanism installed inside the lower head shell (A7); the center of gravity adjustment mechanism consists of a fish head built-in motor (A3), a fish head moving configuration block (A2), a guide rod (A10), and a screw rod (A11); among them, the screw rod (A11) is installed on the output shaft of the fish head built-in motor (A3), and the fish head built-in motor (A3) and the guide rod (A10) are fixed inside the head shell; the fish head moving configuration block (A2) is installed on the screw rod (A11) and the guide rod (A10), and the threaded hole of the fish head moving configuration block (A2) is screwed with the screw rod; The above-mentioned body unit includes a left body unit shell (B7) and a right body unit shell (B1); it also includes a first body unit servo (B2), a first body unit servo disc (B3), a first body unit output shaft (B4), a first body unit bearing (B5), a second body unit servo (B11), a second body unit servo disc (B10), a second body unit output shaft (B9), a second body unit bearing (B8), a large body unit gear (B6), and a small body unit gear (B12) installed inside the right body unit shell (B1); among them, the first body unit output shaft (B4) is fitted with the first body unit bearing (B5) and then fixed to the output rotating shaft of the first body unit servo (B2) through the first body unit servo disc (B3), and the first body unit servo (B2) is fixed at the rear inside of the right body unit shell (B1); the large body unit gear (B6) is spaced from the first body unit bearing (B5) and fitted with the first body unit output shaft (B4) and fixed in the middle of the right body unit shell (B1), and meshes with the small body unit gear (B12), and the small body unit gear (B12) extends out of the body unit; the second body unit output shaft (B9) is fitted with the second body unit bearing (B8) and then fixed to the output rotating shaft of the second body unit servo (B11) through the second body unit servo disc (B10), and the second body unit servo (B11) is fixed at the front inside of the right body unit shell (B1); the end of the second body unit output shaft (B9) extends out of the body unit shell; The tail of the hairtail consists of the left shell of the fish tail (C8), the right shell of the fish tail (C1), the first servo of the fish tail (C3), the steering wheel of the first servo of the fish tail (C4), the first output shaft of the fish tail (C5), the first bearing of the fish tail (C6), the second servo of the fish tail (C12), the steering wheel of the second servo of the fish tail (C11), the second output shaft of the fish tail (C10), the second bearing of the fish tail (C9), the large gear of the fish tail (C7), the small gear of the fish tail (C13), and the end thin sheet of the fish tail (C2). Among them, after the first output shaft of the fish tail (C5) is fitted with the first bearing of the fish tail (C6), it is fixed at the output rotating shaft of the first servo of the fish tail (C3) through the steering wheel of the first servo of the fish tail (C4), and the first servo of the fish tail (C3) is fixed at the rear inside of the right shell of the fish tail (C1). The large gear of the body unit (C7) is spaced from the first bearing of the fish tail (C6) and is fitted with the first output shaft of the fish tail (C5) and fixed in the middle of the right shell of the fish tail (C1), and meshes with the small gear of the fish tail (C13), and the small gear of the fish tail (C13) extends out of the tail of the hairtail. After the second output shaft of the fish tail (C10) is fitted with the second bearing of the fish tail (C9), it is fixed at the output rotating shaft of the second servo of the fish tail (C12) through the steering wheel of the second servo of the fish tail (C11), and the second servo of the fish tail (C12) is fixed at the front inside of the right shell of the fish tail (C1). The end of the second output shaft of the fish tail (C10) extends out of the fish tail shell. The lower shell of the above head (A7) is connected to the second output shaft (B9) of the first adjacent body unit. After the left shell of the body unit and the right shell of the body unit are buckled, they are jointly connected to the second output shaft (B9) of the adjacent body unit behind them; the body unit close to the tail of the hairtail is connected to the second output shaft (C10) of the fish tail. The multi-joint bionic hairtail robot also includes a torsion spring (N1) and a dorsal fin (Q1); the torsion spring sequentially passes through the through holes of the body units, and the above-mentioned small gears of the body units (B12) and the small gears of the fish tail (C13) are sequentially sleeved on the torsion spring and fixedly connected to the torsion spring; the dorsal fin is fixedly connected to the torsion spring and twists with it to achieve undulation.

2. The motion method of the bionic hairtail robot based on the dual-coupled motion of the dorsal fin and the fish body according to claim 1, characterized in that It includes the following processes: First, the symmetry line of the vertical symmetry plane of the body of the multi-joint bionic hairtail robot is called the body center line. When the body center line is in the horizontal plane, the posture in which the dorsal fin (Q1) of the multi-joint bionic hairtail robot is directly above the horizontal plane is called the vertical posture. The angle between each body unit and the adjacent body unit in the direction close to the head of the hairtail is called the forward offset angle, and the angle between each body unit and the adjacent body unit in the direction away from the head of the hairtail is called the backward offset angle. A left offset relative to the forward direction is positive, and a right offset relative to the moving direction is negative. Among them, the positive direction of the body center line is from the tail of the hairtail (W1) to the head of the hairtail (T1). When the head of the hairtail (T1) deviates above the horizontal plane, the angle between the positive direction of the body center line and the horizontal plane is called the elevation angle. When the head of the hairtail (T1) deviates below the horizontal plane, the angle between the positive direction of the body center line and the horizontal plane is called the depression angle. Overall vertical forward swimming: All body units are driven by the first servo of its posterior body unit and the first servo of the fish tail. Their swinging frequencies and amplitudes are exactly the same, but there is a fixed and equal phase difference, thus achieving a standard sinusoidal motion. A flexible dorsal fin is adopted. When all body units swing left and right, the first servo of all body units and the first servo of the fish tail jointly drive the small gears of the body units and the small gears of the fish tail through the large gears of the body units and the large gears of the fish tail, driving the torsion spring to perform torsion with the same frequency and amplitude but with a phase difference, thereby driving the dorsal fin to achieve an independent sinusoidal fluctuation relative to the body units. The vertical cross-sections of each body unit and the flexible surface of the dorsal fin simultaneously generate a backward acting force on the water, and the water generates a forward thrust on the multi-joint bionic hairtail robot, realizing overall forward movement. Overall vertical left or right turning swimming: Several body units near the head of the hairtail remain relatively stationary and have a fixed forward offset angle at the same time; the swinging frequencies of several body units near the tail of the hairtail are exactly the same, but there is a linearly increasing relationship in the swinging amplitudes, and there is a fixed phase difference at the same time. A flexible dorsal fin is adopted. When all body units swing left and right, the first servo of all body units and the first servo of the fish tail jointly drive the small gears of the body units and the small gears of the fish tail through the large gears of the body units and the large gears of the fish tail, driving the torsion spring to perform torsion with the same frequency and amplitude but with a phase difference, thereby driving the dorsal fin to achieve an independent sinusoidal fluctuation relative to the body units. When the forward offset angle is positive, the thrust of the water on the right side is greater than that on the left side, and it is subjected to an unbalanced force, that is, a left-turning torque, to achieve a left turn. When the forward offset angle is negative, the thrust of the water on the left side is greater than that on the right side, and it is subjected to an unbalanced force, that is, a right-turning torque, to achieve a right turn. Overall vertical pitch conversion: A center-of-gravity adjustment mechanism is configured at the head of the hairtail; four configuration blocks are configured inside the rear N body units (Z1~ZN) and the fish tail (W1). The four configuration blocks are divided into two each in the upper and lower, left and right directions, and are symmetrically arranged. When installed, by adjusting the positions of the configuration blocks, the center of gravity of each body unit or the fish tail is made to coincide with the center of buoyancy; after ensuring that the partial centers of gravity of the N body units and the fish tail coincide with the center of buoyancy, pitch conversion is achieved through the relevant movement of the center-of-gravity adjustment mechanism at the head of the hairtail.

3. The motion method of the bionic hairtail robot based on the dual-coupled motion of the dorsal fin and the fish body according to claim 2, characterized in that It includes the following processes: Pitch conversion is achieved through the relevant movement of the center-of-gravity adjustment mechanism at the head of the hairtail. The specific implementation is as follows: In the initial state, the fish head moving configuration block (A2) is located at the middle position of the guide rod (A10); when an upward-looking posture is to be achieved, the built-in motor (A3) of the fish head drives the fish head moving configuration block (A3) to move forward or backward through the screw rod (A11); during the entire movement process of the fish head moving configuration block (A3), the center of gravity of the fish head gradually moves forward or backward, and a torque is formed between gravity and buoyancy. When the target upward-looking posture is reached, the degree of this upward look, that is, the magnitude of the elevation angle, is proportional to the magnitude of the forward or backward displacement of the fish head moving configuration block (A3).

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