A high-mobility manta ray type bionic fish based on buoyancy and gravity center joint adjustment and a diving and floating and obstacle avoidance control method thereof

Abstract

The application discloses a high-mobility manta ray type bionic fish based on joint adjustment of buoyancy and gravity center and a diving and floating and obstacle avoidance control method thereof. The base body of the manta ray type bionic fish comprises a bionic shell, a center cabin and power supply cabins symmetrically arranged on both sides of the center cabin. The center cabin is a sealed structure, and a gravity center adjustment auxiliary device of the center cabin is slidingly arranged close to the head of the bionic fish. The power supply cabin sealing flange, the cabin body and the buoyancy gravity center adjustment device form a sealed structure, the buoyancy gravity center adjustment device is slidingly arranged close to the tail of the bionic fish, the displacement of the buoyancy gravity center adjustment device and the drainage flange on one side is changed, and the buoyancy and the gravity center position of the power supply cabin are controlled. The buoyancy gravity center adjustment device of the left and right power supply cabins and the gravity center adjustment auxiliary device of the center cabin are integrated, the accurate control of the overall buoyancy and gravity center of the bionic fish is effectively realized, the lithium battery pack is used as the counterweight, the counterweight block is not additionally increased, and the mobility and the endurance of the bionic fish are improved.

Description

Technical Field

[0001] This invention relates to the field of biomimetic robots, and more particularly to a highly maneuverable manta ray-like biomimetic fish based on the combined adjustment of buoyancy and center of gravity, and its diving, buoyancy, and obstacle avoidance control method. Background Technology

[0002] Compared to conventional underwater robots, biomimetic robotic fish offer advantages such as high efficiency, high maneuverability, and high stealth, making them suitable for various complex scenarios. Currently, the industry has invented various manta ray-like biomimetic robotic fish. For example, Chinese invention CN202210995754.X discloses a manta ray-like biomimetic fish and its buoyancy adjustment method, which includes a base component and pectoral fins. The pectoral fins are symmetrically arranged on both sides of the base component via variable-volume transition components. The transition components are closed cavity structures composed of transition plates and flexible skin, filled with oil and equipped with a drive mechanism to control the movement of the pectoral fins. A control system and a buoyancy adjustment mechanism are installed on the middle partition of the base component. The buoyancy adjustment mechanism changes the volume of the flexible skin in the transition component by controlling the amount of oil in the transition component, thereby changing the buoyancy of the biomimetic fish. Chinese invention CN202311227974.9 discloses a manta ray-inspired soft-bodied underwater vehicle that utilizes pectoral and caudal fin flapping, gravity gliding, and propeller propulsion. Based on the shape and function of a manta ray, it adds gravity buoyancy adjustment and propeller propulsion to the existing pectoral and caudal fin flapping capabilities. The vehicle uses the flapping of its left and right pectoral fins to achieve forward swimming and turning movements; it uses gravity buoyancy adjustment to achieve gliding movements; and during flapping and gliding movements, it uses the interaction between its caudal fin and water flow to adjust its pitch attitude. Chinese invention CN202310513000.0 discloses a composite buoyancy adjustment device, an autonomous underwater vehicle, and its control method. This composite buoyancy adjustment device installs a buoyancy adjustment mechanism and a pitch adjustment mechanism in a sealed chamber, using piston movement to adjust the overall buoyancy, while simultaneously adjusting an additional counterweight to achieve pitch adjustment. However, the above inventions have the following shortcomings: The first invention, while achieving the buoyancy and descent of the bionic fish by adjusting the oil on both sides, suffers from the problem of not being able to precisely control the balance of oil on both sides, causing the bionic fish's center of gravity to shift during buoyancy adjustment. The second invention's pectoral fins utilize a flapping motion combining spanwise and chordal waves, resulting in relatively low thrust. Although adding a propeller propulsion device improves propulsion efficiency, it suffers from the same problem of high noise levels as traditional underwater robots. The third invention, while using a piston-type buoyancy adjustment mechanism to adjust buoyancy, requires additional counterweights for pitch adjustment, resulting in a large space requirement.

[0003] Compared to the highly maneuverable tail-fin-propelled bionic fish, the manta ray-like bionic fish proposed in existing patents primarily uses pectoral fins as a propulsion mechanism. While it offers strong stability during swimming, its maneuverability is relatively poor. Furthermore, the manta ray-like bionic fish is relatively large, making it difficult to avoid obstacles by relying solely on pectoral fin flapping for turning in place, especially during high-speed, straight-line navigation missions requiring emergency obstacle avoidance. In addition, while controlling buoyancy alone can adjust depth with low energy consumption, the adjustment speed is slow for large-scale depth adjustments. Moreover, the operation of the buoyancy adjustment device causes a shift in the overall center of gravity, making it impossible to adjust depth at a specified pitch posture. While using pectoral fin flapping combined with tail fin oscillation for depth adjustment is faster, it is difficult to stably maintain the manta ray-like bionic fish at a fixed depth, and this adjustment method is energy-intensive. Moreover, when manta ray-like bionic fish are needed for underwater operations, they are prone to structural damage when colliding with the surrounding environment during the flapping of their pectoral or caudal fins to land or take off safely underwater. Summary of the Invention

[0004] Objectives of this invention: Firstly, this invention aims to provide a highly maneuverable manta ray-like bionic fish that can jointly adjust buoyancy, center of gravity, and pectoral fins. Secondly, this invention provides a method for controlling the buoyancy and diving of a manta ray-like bionic fish that achieves rapid and accurate depth adjustment while reducing energy consumption during depth adjustment tasks, and enables soft landing and safe start-up on the seabed, effectively improving the safety of underwater operations and retrieval. Thirdly, this invention provides a highly maneuverable obstacle avoidance and steering control method when encountering obstacles and needing emergency obstacle avoidance.

[0005] Technical Solution: The highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity described in this invention includes a base and pectoral fins. The base includes a bionic shell, a central chamber, and power supply chambers symmetrically arranged on both sides of the central chamber. The central chamber is a sealed structure. The center of gravity adjustment auxiliary device of the central chamber is slidably arranged near the head of the bionic fish to change the center of gravity position of the central chamber, thereby controlling the pitch angle of the head. The power supply chamber includes a sealing flange, a chamber body, a buoyancy and center of gravity adjustment device, and an inlet / drainage flange. The sealing flange, chamber body, and buoyancy and center of gravity adjustment device form a sealed structure. The buoyancy and center of gravity adjustment device is slidably arranged near the tail of the bionic fish to change the drainage volume on the side of the buoyancy and center of gravity adjustment device and the inlet / drainage flange, thereby controlling the buoyancy and center of gravity position of the power supply chamber. The bionic shell is provided with inlet / drainage ports.

[0006] Furthermore, the center of gravity adjustment auxiliary device includes a sealed chamber flange, a linear servo, and a counterweight unit. The counterweight unit is located inside the sealed chamber flange, and the linear servo is installed on the outside of the sealed chamber flange through a connecting plate and a bracket. The telescopic rod of the linear servo is connected to the counterweight unit to control the position of the counterweight unit.

[0007] Furthermore, the counterweight unit includes a first lithium battery pack, a fixed support, and a mounting plate. The fixed support and the mounting plate are connected by a connecting rod, and the first lithium battery pack is mounted on the fixed support.

[0008] Furthermore, the central module also includes a control system, a central module intermediate body, a central module rear sealing flange, and a central module rear end cover.

[0009] Furthermore, the buoyancy center of gravity adjustment device includes a linear servo, a second lithium battery pack, a piston, and a piston seal.

[0010] Furthermore, digital servos are installed at both ends of the power supply compartment, and the pectoral fins are connected to the digital servos via fin rays and connecting brackets; each digital servo is equipped with a CPG control unit.

[0011] The buoyancy control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity, as described in this invention, includes the following steps:

[0012] The initial state of the manta ray-like bionic fish is assumed to be a suspended state. In this state, the piston positions of the buoyancy and center of gravity adjustment devices in the left and right power supply compartments are x and x, respectively. l0 and x r0 The position corresponding to the middle of the piston stroke is defined as the positive direction when the piston pushes outward, and the maximum stroke positions are x and x. l0 +x max and x r0 +x max The minimum positions of the travel distances are x l0 -x max and x r0 -x max The lithium battery pack of the center of gravity adjustment auxiliary device is located at position x. a0 x a0 Corresponding to the middle position of the first lithium battery pack's travel distance, the forward movement of the lithium battery pack is defined as the positive direction, and the maximum travel position is x. a0 +x amax The minimum position of the journey is x a0 -x amax The flexible pectoral fins are in their initial horizontal position, and the current buoyancy f of the manta ray-like bionic fish is... 浮 Equal to the current gravity G;

[0013] The pectoral fins are controlled by two CPG control units; the CPG model is...

[0014]

[0015] Among them, a i b i and x i Let A represent the amplitude, offset, and phase of the i-th oscillator; i = 1, 2, 3, 4 are the phase oscillators corresponding to the left rear, left front, right rear, and right front servo motors of the manta ray bionic fish, respectively; i With B i These represent the expected amplitude and expected offset of the i-th oscillator, respectively; α i With β i These are the convergence coefficients for amplitude and offset, respectively; f i The oscillation frequency is μ. ij x is the coupling coefficient between the i-th oscillator and the j-th oscillator; j The current phase of the j-th oscillator; θ represents the phase difference between the i-th oscillator and the j-th oscillator. i Let be the servo angle output by the i-th phase oscillator;

[0016] Define distance-to-target depth thresholds ε1, ε2, and ε3, where ε1 is the distance-to-target depth threshold when the manta ray bionic fish switches from a rapid descent phase to a slow gliding descent phase or from a rapid ascent phase to a slow gliding ascent phase when performing a dive or ascent mission; ε2 is the distance-to-target depth threshold when the manta ray bionic fish switches from a slow gliding descent phase to a near-target fine-tuning descent phase or from a slow gliding ascent phase to a near-target fine-tuning ascent phase; and ε3 is the distance-to-target depth threshold when the manta ray bionic fish switches from a near-target fine-tuning descent phase or a near-target fine-tuning ascent phase to the target depth.

[0017] Through the target depth d tar With current depth d t The difference in magnitude |d tar -d t | Compare with the target depth thresholds ε1, ε2, and ε3, and then switch to different surfacing or descent phases.

[0018] Furthermore, when (d tar -d t When ) > 0, execute the dive mission;

[0019] When |d tar -d t When |≥ε1, the rapid descent phase begins. The piston moves linearly from the initial middle position to the minimum stroke position, the displacement decreases to its minimum value, and the buoyancy of the manta ray-like bionic fish is adjusted from neutral buoyancy to minimum buoyancy. At this time, the buoyancy f 浮When the gravitational force is less than G, the center of gravity shifts forward, and the manta ray-like biomimetic fish adjusts from a horizontal posture to a head-pointing-to-bottom posture, and dives towards the bottom in this posture, with the pectoral fins maintaining a fixed phase difference forward and backward. Fixed amplitude A i1 Fixed frequency f i1 Amplitude bias B with sum to zero i The flapping motion provides a vertical downward thrust along the direction the manta ray-like bionic fish is pointing, enabling it to dive rapidly until ε1 > |d. tar -d t |≥ε2;

[0020] When ε1>|d tar -d t When |≥ε2, the system enters a slow gliding descent phase. The CPG controller adjusts the pectoral fins to their initial positions, and the lithium battery pack of the center capsule's center of gravity adjustment auxiliary device is positioned at x. adown for

[0021]

[0022] The center of gravity of the manta ray-like biomimetic fish gradually shifts backward, and when |d tar -d t When |=ε2, the position of the lithium battery pack of the center of gravity adjustment auxiliary device is adjusted to the minimum stroke position x. a0 -x amax The manta ray-like bionic fish's center of gravity returns to its initial central position. During this process, the manta ray-like bionic fish's pitch attitude changes from vertical downwards and upwards, eventually reaching a horizontal attitude. Maintaining minimal buoyancy, the manta ray-like bionic fish continues to descend. In the slow gliding descent phase, it decelerates downwards and gradually descends to a horizontal attitude until ε2 > |d. tar -d t |≥ε1;

[0023] When ε2>|d tar -d t When |≥ε3, the target fine-tuning descent phase begins. The pectoral fins maintain their initial horizontal position, and the pistons move linearly from their minimum stroke position to a position close to their minimum stroke position. The stroke position; simultaneously, the position of the lithium battery pack of the center of gravity adjustment assist device is linearly moved to the position closest to the minimum stroke position. During the flight, the manta ray-like bionic fish maintains its center of gravity in the initial position and slowly descends in a horizontal posture until |d tar -d t |<ε3;

[0024] When |d tar -d tWhen | < ε3, the target depth stage begins. The piston moves to the middle position, and the lithium battery pack of the center of gravity adjustment auxiliary device moves linearly to the middle position. The manta ray-like bionic fish hovers at the target depth in a horizontal posture or achieves a soft landing on the seabed, and the mission is completed.

[0025] Furthermore, immediately (d tar -d t When ) < 0, determine the current distance D of the manta ray-like bionic fish from the bottom of the water. t Is the safe distance from the bottom of the water exceeded?

[0026] If D t If ξ < ξ, then the manta ray-like bionic fish maintains the initial position of its pectoral fins, and the piston moves linearly to near its maximum stroke position. The stroke position linearly moves the position of the lithium battery pack of the center of gravity adjustment assist device to near the maximum stroke position. At the destination, the manta ray-like bionic fish slowly rises horizontally until it reaches position D. t >ξ;

[0027] When D t When the distance exceeds ξ, the manta ray-like bionic fish has exceeded the safe distance from the bottom of the water and is about to rise to the surface.

[0028] When |d tar -d t When |≥ε1, the rapid ascent phase begins, and the piston moves linearly from the middle position to the maximum stroke position. The buoyancy of the manta ray-like bionic fish is adjusted from neutral buoyancy to maximum buoyancy, at which point the buoyancy f 浮 When the force exceeds gravity G, the center of gravity shifts backward, and the manta ray-like bionic fish adjusts from a horizontal posture to a head-up, water-facing posture, and floats towards the surface. At this point, the manta ray-like bionic fish utilizes a designed CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i1 Fixed frequency f i1 Amplitude bias B with sum to zero i The flapping motion provides the manta ray-like bionic fish with a vertical upward thrust along the direction its head is pointing, enabling the manta ray-like bionic fish to rise rapidly until ε1 > |d. tar -d t |≥ε2;

[0029] When ε1>|d tar -d t When |≥ε2, enter the slow gliding ascent phase, pectoral fins are adjusted to their initial positions, and the position of the lithium battery pack of the center capsule's center of gravity adjustment auxiliary device is x. aup for

[0030]

[0031] During this process, the center of gravity of the manta ray-like bionic fish gradually shifts forward, and when |d tar -d t When |=ε2, the position of the lithium battery pack of the center of gravity adjustment auxiliary device is adjusted to the maximum stroke position x. a0 +x amax The manta ray-like bionic fish's center of gravity returns to its initial central position. During this process, the manta ray-like bionic fish's pitch attitude gradually changes from vertical upward to downward and finally reaches a horizontal attitude. Meanwhile, the manta ray-like bionic fish maintains maximum buoyancy and continues to rise, decelerating upward and gliding until it gradually rises to a horizontal attitude, until ε2>|d tar -d t |≥ε1;

[0032] When ε2>|d tar -d t When |≥ε1, the system enters the fine-tuning and upward movement phase close to the target. The pectoral fins maintain their initial horizontal position, and the piston moves linearly from its maximum stroke position to a position close to its maximum stroke position. Simultaneously, the position of the lithium battery pack of the center of gravity adjustment assist device is linearly moved to near the maximum stroke position. During its journey, the manta ray-like bionic fish maintains its center of gravity in the initial position and slowly rises horizontally until |d tar -d t |<ε3;

[0033] When |d tar -d t When | < ε3, the target depth stage begins. The piston moves linearly to the middle position, the lithium battery pack of the center of gravity adjustment auxiliary device moves linearly to the middle position, and the manta ray-like bionic fish hovers at the target depth in a horizontal posture, completing the mission.

[0034] The obstacle avoidance and steering control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity, as described in this invention, includes the following steps:

[0035] The preset distances between the manta ray-shaped bionic fish's left and right front sides and the obstacle are D respectively. lt and D rt The manta ray-like bionic fish is currently swimming forward at a linear speed of v. t The speed threshold for the manta ray bionic fish to perform high-maneuverability obstacle avoidance and turning tasks is v1; the distance threshold for the manta ray bionic fish to enter the high-maneuverability large-angle turning mode is dis1; and the distance threshold for the manta ray bionic fish to enter the high-maneuverability small-angle turning mode is dis2.

[0036] The CPG controller is preset to have a fixed phase difference in parameters during high-maneuverability obstacle avoidance and steering missions. Fixed amplitude Ai2 Fixed frequency f i2 Dynamically adjust amplitude bias B i The preset maximum amplitude offset is B. imax Amplitude bias B i >0;

[0037] When the swimming speed v t ≥v1 and the minimum distance to the obstacle min(D) lt D rt When )≤dis1, the manta ray-like bionic fish autonomously performs highly maneuverable obstacle avoidance and turning tasks;

[0038] When v t ≥v1 and dis1≥min(D) lt D rt When )≥dis2, if D lt >D rt Entering a high-maneuverability, small-angle left-turn mode, the first piston in the left power supply compartment moves linearly from the middle position to the minimum stroke position, while the second piston in the right power supply compartment moves linearly from the middle position to the maximum stroke position. The manta ray-like bionic fish maintains balance in the forward and backward directions, while the center of buoyancy shifts to the right in the left and right directions. The manta ray-like bionic fish rolls 90° to the left, presenting an attitude where the left and right pectoral fins are in the vertical direction with the right pectoral fin pointing upwards. The buoyancy of the manta ray-like bionic fish equals its weight. At this time, the manta ray-like bionic fish uses a CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i2 Fixed frequency f i2 Sum of values The amplitude offset flapping motion provides the manta ray-like bionic fish with a torque to turn left, enabling it to perform highly maneuverable small-angle left turns in three-dimensional space and avoid obstacles on the right; when the current distance between the manta ray-like bionic fish and the obstacle is D... obst The distance is greater than the safe distance threshold from the obstacle. safe And the current lateral distance deviating from the initial heading is D. latt The lateral safety distance threshold greater than the deviation from the initial heading is dis latsafe At this time, the first and second pistons are adjusted to the initial middle position, the pectoral fins are adjusted to the initial zero position, the buoyancy center of the manta ray-like bionic fish returns to the center position in the left and right directions, the manta ray-like bionic fish rolls to the right and turns to a horizontal attitude, the high-maneuverability obstacle avoidance mission is completed, and the cruise mission continues.

[0039] When v t ≥v1 and min(D) lt D rt When ) < dis2, if D lt >D rtWhen entering a high-maneuverability, large-angle left-turn mode, the first piston moves linearly from the initial middle position to the minimum stroke position, and the second piston moves linearly from the initial middle position to the maximum stroke position. The manta ray-like bionic fish maintains balance in the forward and backward directions, while the center of buoyancy shifts to the right in the left and right directions. The manta ray-like bionic fish rolls 90° to the left, presenting an attitude where the left and right pectoral fins are in the vertical direction with the right pectoral fin pointing upwards. The buoyancy of the manta ray-like bionic fish equals its weight. At this time, the manta ray-like bionic fish uses a CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i2 Fixed frequency f i2 The sum is B imax The amplitude offset flapping provides a larger torque for the manta ray-like bionic fish to turn left, enabling the manta ray-like bionic fish to make highly maneuverable large-angle left turns in three-dimensional space and avoid obstacles on the right; when D obst >dis safe And D latt >dis latsafe At this time, the first and second pistons are adjusted to the initial middle position, the pectoral fins are adjusted to the initial zero position, the buoyancy center of the manta ray-like bionic fish returns to the center position in the left and right directions, the manta ray-like bionic fish rolls to the right and turns to a horizontal attitude, the high-maneuverability obstacle avoidance mission is completed, and the cruise mission continues.

[0040] When v t ≥v1 and dis1≥min(D) lt D rt When )≥dis2, if D lt <D rt When entering a high-maneuverability, small-angle right-turn mode, the first piston moves linearly from its initial middle position to its maximum stroke, and the second piston moves linearly from its initial middle position to its minimum stroke. The manta ray-like bionic fish maintains balance in the forward and backward directions, while its center of buoyancy shifts to the left in the left and right directions. The manta ray-like bionic fish rolls 90° to the right, assuming a posture where its pectoral fins are vertical with the left pectoral fin pointing upwards. At this point, the buoyancy of the manta ray-like bionic fish equals its weight. The manta ray-like bionic fish utilizes a CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i2 Fixed frequency f i2 Sum of values The amplitude offset flapping motion provides the manta ray-like bionic fish with a torque for turning right, enabling the manta ray-like bionic fish to make highly maneuverable, small-angle right turns in three-dimensional space to avoid obstacles on the left; when D obst >dis safe And D latt >dis latsafeAt this time, the first and second pistons are adjusted to the initial middle position, the pectoral fins are adjusted to the initial zero position, the buoyancy center of the manta ray-like bionic fish returns to the center position in the left and right directions, the manta ray-like bionic fish rolls to the left to a horizontal attitude, the high-maneuverability obstacle avoidance mission is completed, and the cruise mission continues.

[0041] When v t ≥v1 and min(D) lt D rt When ) < dis2, if D lt <D rt Entering a high-maneuverability, large-angle right-turn mode, the first piston moves linearly from the initial middle position to its maximum stroke, while the second piston moves linearly from the initial middle position to its minimum stroke. The manta ray-like bionic fish maintains balance in the forward and backward directions, while its center of buoyancy shifts to the left in the left-right direction. The manta ray-like bionic fish rolls 90° to the right, assuming a posture where its pectoral fins are vertical with the left pectoral fin pointing upwards. At this point, the buoyancy of the manta ray-like bionic fish equals its weight. Simultaneously, the manta ray-like bionic fish utilizes a CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i2 Fixed frequency f i2 The sum is B imax The amplitude offset flapping provides a larger right-turning torque for the manta ray-like bionic fish, enabling it to achieve high maneuverability and large-angle right turns in three-dimensional space, avoiding obstacles on the left; when D obst >dis safe And D latt >dis latsafe At this time, the first and second pistons are adjusted to the initial middle position, the pectoral fins are adjusted to the initial zero position, the buoyancy center of the manta ray-like bionic fish returns to the center position in the left and right directions, the manta ray-like bionic fish rolls to the left to a horizontal attitude, the high-maneuverability obstacle avoidance mission is completed, and the cruise mission continues.

[0042] Beneficial Effects: Compared with existing technologies, the significant advantages of this invention are: 1. By integrating the buoyancy and center of gravity adjustment devices of the left and right power supply compartments with the center of gravity adjustment auxiliary device of the central compartment, this invention effectively achieves precise control of the overall buoyancy and center of gravity of the bionic fish. Furthermore, using a lithium battery pack as counterweight eliminates the need for additional counterweights, thus improving the bionic fish's maneuverability and endurance. 2. The diving and buoyancy control method for highly maneuverable manta ray-like bionic fish proposed in this invention, by coordinating the buoyancy and center of gravity adjustment devices with the center of gravity adjustment auxiliary device, and in conjunction with the CPG-controlled flexible pectoral fins, enables joint adjustment of buoyancy and pitch attitude during ascent and descent; allowing the bionic fish to respond quickly. To meet the needs of depth changes, it can achieve rapid and accurate depth adjustment with low energy consumption, and can perform soft landing and safe start-up underwater. It effectively avoids structural damage caused by the manta ray-like bionic fish colliding with the surrounding environment due to the complex underwater environment and the direct flapping of the flexible pectoral fins, which significantly improves the safety and stability of underwater operations; 3. The high-maneuverability obstacle avoidance and steering control method described in this invention, combined with the left and right buoyancy center of gravity adjustment device and the different amplitude offset flapping of the pectoral fins, enables the manta ray-like bionic fish to achieve flexible three-dimensional turning in high-speed swimming, quickly avoid obstacles, avoid structural damage, and effectively improve the survival ability of the manta ray-like bionic fish in complex environments. Attached Figure Description

[0043] Figure 1 A schematic diagram of the structure of a highly mobile manta ray-like bionic fish;

[0044] Figure 2 This is a structural diagram of the central module;

[0045] Figure 3 This is a schematic diagram of the center of gravity adjustment auxiliary device;

[0046] Figure 4 This is a schematic diagram of the control system.

[0047] Figure 5 A schematic diagram of the structure of the left pectoral fin and the left power supply compartment;

[0048] Figure 6 This is a schematic diagram of the first buoyancy center of gravity adjustment device.

[0049] Figure 7 This is a schematic diagram of the biomimetic shell structure;

[0050] Figure 8 This is a schematic diagram of the structure at the bottom of the biomimetic shell;

[0051] Figure 9 This is a schematic diagram of the mounting plate structure;

[0052] Figure 10 This is a structural diagram of the mounting plate bracket;

[0053] Figure 11 This is a schematic diagram of the heat dissipation module.

[0054] Figure 12 A flowchart illustrating the process of receiving submersion / surface commands;

[0055] Figure 13 A flowchart illustrating the process of performing a dive mission;

[0056] Figure 14 A flowchart illustrating the process of performing an ascent task;

[0057] Figure 15 This is a schematic diagram of the CPG model.

[0058] Figure 16 This is a diagram illustrating the various stages of the descent to the bottom of the water.

[0059] Figure 17 A schematic diagram illustrating the various stages of ascending from the seabed to the target depth;

[0060] Figure 18 A flowchart for performing a high-maneuverability obstacle avoidance and turning task. Detailed Implementation

[0061] The invention will now be further described with reference to the accompanying drawings.

[0062] like Figure 1 As shown, the highly maneuverable manta ray-shaped bionic fish based on the combined adjustment of buoyancy and center of gravity of the present invention includes a central cabin 1, a left power supply cabin 4, a right power supply cabin 5, a left pectoral fin 2, a right pectoral fin 3, and a bionic shell 6; the central cabin 1 is the main control cabin of the entire manta ray-shaped bionic fish and includes a center of gravity adjustment auxiliary device; the left power supply cabin 4 and the right power supply cabin 5 are fixed by the bionic shell 6 and symmetrically distributed on both sides of the central cabin 1; the left pectoral fin 2 and the right pectoral fin 3 are fixed to the left power supply cabin 2 and the right power supply cabin 3 and symmetrically distributed on both sides of the left power supply cabin 2 and the right power supply cabin 3.

[0063] like Figure 2 As shown, the central cabin 1 includes a center of gravity adjustment auxiliary device 11, a control system 12, a central cabin intermediate body 13, a central cabin rear sealing flange 14, and a central cabin rear end cover 15.

[0064] like Figure 3As shown, the center of gravity adjustment auxiliary device 11 includes a center of gravity adjustment auxiliary device sealing chamber flange 111, a first linear servo bracket 112, a first linear servo 113, a first linear servo bracket connecting plate 114, a first lithium battery pack fixing support 115, a first lithium battery pack mounting plate 116, a first lithium battery pack connecting rod 117, and a first lithium battery pack 118. The center of gravity adjustment auxiliary device sealing chamber flange 111 is a cylindrical sealing chamber, which is dynamically sealed to the cylindrical central chamber intermediate chamber 13 by two layers of O-rings and fixedly connected by six circumferentially distributed screws. The center of gravity adjustment auxiliary device 11 is located at the front end of the central chamber 1. The inner circular end face edge of the center of gravity adjustment auxiliary device sealing chamber flange 111 has six circumferentially distributed threaded holes. The first linear servo bracket connecting plate 114 is a circular metal plate with a circular hole in the center. The edges of the first linear servo bracket connecting plate 114 and the circular hole both have six circumferentially distributed circular through holes. The first linear servo bracket connecting plate 114 is fixed to the inner end face of the sealing chamber flange 111 of the center of gravity adjustment auxiliary device by six circumferentially distributed screws. The first linear servo 113 is placed in the square groove of the first linear servo bracket 112 and fixed to the first linear servo bracket 112 by bolts and nuts. The base of the first linear servo bracket 112 is a circular plate with square holes and six circumferentially distributed through holes on its edge. The first linear servo bracket 112 and the first linear servo bracket connecting plate 114 are connected by six circumferentially distributed bolts. The first lithium battery pack fixing support 115 consists of a circular plate with 12 grooves for placing the first lithium battery pack 118 and a cylindrical guide rod. The cylindrical guide rod has external threads near its outer end face for threaded connection with the first linear servo 113 and is locked by a lock nut. The first lithium battery pack mounting bracket 115 has six circular threaded holes on its edge, and the first lithium battery pack mounting plate 116 has six circular through holes on its edge. The first lithium battery pack mounting plate 116 has 12 grooves for fixing the first lithium battery pack. The first lithium battery pack 118 and six circumferentially distributed connecting rods 117 of the first lithium battery pack are placed between the first lithium battery pack mounting bracket 115 and the first lithium battery pack mounting plate 116. One end of the first lithium battery pack connecting rod 117 has an external thread, and the other end has an internal thread. The first lithium battery pack connecting rod 117 is threaded to the first lithium battery pack mounting bracket 115 through the external thread. The first lithium battery pack mounting plate 116 is fixed to the internal thread end of the six circumferentially distributed connecting rods 117 by six circumferentially distributed screws, thus fixing the position of the first lithium battery pack 118.The center of gravity adjustment auxiliary device 11 uses the first lithium battery pack as a counterweight. By controlling the first linear servo 113 to push and pull the first lithium battery pack 118, the center of gravity of the manta ray-like bionic fish is adjusted. When the first linear servo 113 pushes the first lithium battery pack 118, the center of gravity of the manta ray-like bionic fish moves forward, its head tilts downward, and its pitch angle decreases. When the first linear servo 113 pulls the first lithium battery pack 118, the center of gravity of the manta ray-like bionic fish moves backward, its head tilts upward, and its pitch angle increases. The center of gravity adjustment auxiliary device 11 works in conjunction with the left and right buoyancy center of gravity adjustment devices. After the left and right buoyancy center of gravity adjustment devices adjust the buoyancy, the center of gravity adjustment auxiliary device 11 plays an auxiliary role in adjusting the center of gravity so that the manta ray-like bionic fish swims or glides in the desired pitch posture.

[0065] like Figure 2 As shown, the cylindrical ends of the central cabin intermediate compartment 13 are machined with symmetrical flat surfaces, which are fixed to the central cabin intermediate compartment 13 by contact with the bionic shell 6. The central cabin rear sealing flange 14 achieves dynamic sealing with the central cabin intermediate compartment 13 through two O-rings. The edge of the central cabin rear sealing flange 14 has six circumferentially distributed circular through holes. The outer end face of the central cabin rear sealing flange 14 has a circular hole in the middle, and the edge of the circular hole has a sealing ring groove. The central cabin rear sealing flange 14 achieves static sealing with the central cabin rear end cover 15 through O-rings. The edge of the central cabin rear end cover 15 has six circumferentially distributed circular through holes. The central cabin intermediate compartment 13, the central cabin rear sealing flange 14, and the central cabin rear end cover 15 are fixedly connected by six circumferentially distributed screws. The end face of the central cabin rear end cover 15 has twelve evenly distributed circular through holes for the installation 1210 of the waterproof switch 129, the depth sensor 128, and the aviation plug.

[0066] like Figure 4As shown, the control system 12 includes a microcomputer 122, a heat sink 1211, a servo extension board 123, a LoRa module 124, an attitude sensor 125, a GPS module 126, a depth sensor calculation board 127, and a depth sensor 128, a waterproof switch 129, and an aviation connector 1210, all mounted on an internal mounting plate 121 via copper pillars. It also includes a first mounting plate bracket 1212, a second mounting plate bracket 1214, and mounting plate bracket connecting rods 1213. One end of the heat sink 1211 is attached to the chip of the microcomputer 122, and the other end is attached to the first linear servo bracket connecting plate 114 of the buoyancy adjustment device 11, thereby dissipating heat to the outside through the central cabin intermediate compartment 13. The mounting plate 121 is installed in the square grooves of the first mounting plate bracket 1212 and the second mounting plate bracket 1214, and is connected by four mounting plate bracket connecting rods 1213. The mounting plate 121 has a square slot at one end for placing the first linear servo bracket 112 of the center of gravity adjustment auxiliary device 11, thereby improving space utilization.

[0067] like Figure 5 As shown, the left pectoral fin 2 includes a front servo bracket 21, a rear servo bracket 22, a servo flange 212, a front digital servo 23, a rear digital servo 24, a front fin ray connecting support 25, a rear fin ray connecting support 26, a front lower fin ray 27, a front upper fin ray 29, a rear lower fin ray 28, a rear upper fin ray 210, and a flexible fin membrane 211. The front servo bracket 21 and the rear servo bracket 22 are mounted on the outside of the front sealing flange 41 and the rear drainage flange 42 of the power supply compartment by screws. The front digital servo 23 is connected to the front fin connecting support 25 by screws and servo flange 212. The rear digital servo 24 is connected to the rear fin connecting support 26 by screws and servo flange 212. The rotation axes of the front digital servo 23 and the rear digital servo 24 are on the same axis. The flexible fin membrane 211 is made of soft silicone and is fixed between the front lower fin 27 and the front upper fin 29, and the rear lower fin 28 and the rear upper fin 210 by screws. The front lower fin 27 and the rear lower fin 28 are respectively installed in the grooves of the front fin connecting support 25 and the rear fin connecting support 26 and are fixed by screws.

[0068] The left-side power supply compartment includes a first power supply compartment sealing flange 41, a first power supply compartment intermediate compartment 42, a first power supply compartment rear drainage flange 43, and a first buoyancy center of gravity adjustment device 44. The first power supply compartment sealing flange 41 has four threaded holes on its outer side, which are connected to the front servo bracket 21 by screws. The first power supply compartment sealing flange 41 is dynamically sealed to the first power supply compartment intermediate compartment 42 by O-rings. The edge of the first power supply compartment sealing flange 41 has six circumferentially distributed circular through holes. The first power supply compartment sealing flange 41 is connected to the first power supply compartment intermediate compartment 42 by six circumferentially distributed screws. The outer end face of the first power supply compartment sealing flange 41 has a circular through hole for power supply and signal lines to pass through. The edge of the inner end face of the first power supply compartment sealing flange 41 has six circumferentially distributed threaded holes. The cylindrical ends of the intermediate compartment 42 are machined with symmetrical flat surfaces, which are used to fix the first power supply compartment intermediate compartment 42 by contacting the bionic shell 6. The outer end face of the first power supply compartment rear drainage flange 43 is provided with four threaded holes, which are connected to the rear servo bracket 22 by screws. The edge of the first power supply compartment rear drainage flange 43 is provided with six circumferentially distributed circular through holes. The first power supply compartment rear drainage flange 43 and the first power supply compartment intermediate compartment 42 are connected by six circumferentially distributed screws. The first power supply compartment rear drainage flange 43 is provided with a waist-shaped hole in the middle, which is used by the first buoyancy center of gravity adjustment device 45 to drain the water in the first power supply compartment intermediate compartment 42.

[0069] like Figure 6As shown, the first buoyancy center of gravity adjustment device 44 includes a second linear servo bracket 441, a second linear servo 442, a first piston 443, a first piston sealing ring 444, a second lithium battery pack fixing support 445, a second lithium battery pack mounting plate 446, a second lithium battery pack 447, and a second lithium battery pack connecting rod 448. The second linear servo bracket 441 consists of a circular plate with a central hole and an L-shaped fixing plate. The circular plate of the second linear servo bracket 441 has six evenly distributed circular through holes along its edge. The second linear servo bracket 441 is connected to the first power supply compartment sealing flange 41 by six evenly distributed screws. The second linear servo 442 is mounted on the L-shaped fixing plate of the second linear servo bracket 441 and connected to the second linear servo bracket 441 by screws and nuts. The first piston 443 consists of a piston and a piston rod. The piston rod has external threads near its outer end for threaded connection with the second linear servo 442, and is locked by a lock nut. The first piston 443 achieves a dynamic seal with the intermediate compartment 42 of the first power supply compartment through a first piston sealing ring 444. The first piston 443 has six circumferentially distributed threaded holes on its inner end face, while the second lithium battery pack mounting plate 445 has a circular hole at its center for the piston rod of the first piston 443 to pass through. The second lithium battery pack mounting plate 445 has six circumferentially distributed through holes and six circumferentially distributed circular grooves for fixing the second lithium battery pack 447. The second lithium battery pack mounting plate 446 has a circular hole at its center for the piston rod of the first piston 443 to pass through. The second lithium battery pack mounting plate 446 has six circumferentially distributed through holes and six circumferentially distributed circular grooves for fixing the second lithium battery pack 447. The second lithium battery pack 447 and six circumferentially distributed connecting rods 448 of the second lithium battery pack are placed between the second lithium battery pack mounting plate 445 and the second lithium battery pack mounting plate 446. The second battery pack connecting rod 448 has an external thread at one end and an internal thread at the other end. The second lithium battery pack connecting rod 448 is connected to the second lithium battery pack fixing support 445 and the first piston 443 through the external thread. The second lithium battery pack mounting plate 446 is fixed to one end of the internal thread of the second lithium battery pack connecting rod 446 through six circumferentially distributed screws, and fixes the position of the second lithium battery pack 443.The first buoyancy and center of gravity adjustment device 44 uses the second lithium battery pack 448 and the first piston 443 as counterweights. By controlling the second linear servo 442 to push and pull the second lithium battery pack 447 and the first piston 443, the volume and center of gravity inside the left power supply compartment 4 are changed. When the second linear servo 442 pushes the second lithium battery pack 447 and the first piston 443, the internal volume of the left power supply compartment 4 increases, the displacement increases, and thus the buoyancy of the left power supply compartment 4 increases. At the same time, the center of gravity of the left power supply compartment 4 shifts backward. When the second linear servo 442 pulls the second lithium battery pack 447 and the first piston 443, the internal volume of the left power supply compartment 4 decreases, the displacement decreases, and thus the buoyancy of the left power supply compartment 4 decreases. At the same time, the center of gravity of the left power supply compartment 4 shifts forward.

[0070] The right power supply compartment 3 and the left power supply compartment 4 have the same structure and are symmetrically distributed. By jointly adjusting the buoyancy and center of gravity adjustment devices of the left and right power supply compartments 4 and 3, when both pistons and lithium battery packs move forward, the overall displacement of the manta ray-shaped bionic fish decreases, and the buoyancy decreases. At the same time, due to the forward shift of the center of gravity, the head of the manta ray-shaped bionic fish tilts downward, and the pitch angle decreases. When both pistons and lithium battery packs move backward, the overall displacement of the manta ray-shaped bionic fish increases, and the buoyancy increases. At the same time, due to the backward shift of the center of gravity, the head of the manta ray-shaped bionic fish tilts upward, and the pitch angle increases. By jointly adjusting the buoyancy and center of gravity adjustment devices of the left and right power supply compartments 4 and 3, as well as the center adjustment auxiliary device 11 of the central compartment, it is possible to adjust the buoyancy and adjust the pitch angle of the manta ray-shaped bionic fish simultaneously.

[0071] like Figure 7 As shown, the bionic shell 6 includes a lower bionic shell 61 and an upper bionic shell 62, which cover and support the central cabin 1, the left power supply cabin 4, and the right power supply cabin 3. The bionic shell 6 is made of lightweight, high-strength materials to ensure durability and corrosion resistance. The upper bionic shell 62 and the lower bionic shell 61 are connected by threaded sleeves and screws. The overall cross-section of the bionic shell 6 is an airfoil-like cross-section. A three-in-one antenna 63 is installed on the upper bionic shell 62 for connecting to the LoRa module 124, GPS module 126, and microcomputer 122 in the central cabin to realize the transmission and reception of wireless signals.

[0072] like Figure 8As shown, the lower bionic housing 61 is equipped with a camera and infrared ranging sensor bracket 64, a waterproof camera 66, a first infrared ranging sensor 67, a second infrared ranging sensor 68, an ultrasonic ranging sensor bracket 65, and an ultrasonic ranging sensor 69. The waterproof camera 66, the first infrared ranging sensor 67, and the second infrared ranging sensor 68 are fixed to the camera and infrared ranging sensor bracket 64 using waterproof adhesive. The camera and infrared ranging sensor bracket 64 is fixed to the front of the lower bionic housing 61 with screws. The ultrasonic ranging sensor 69 is fixed to the ultrasonic ranging sensor bracket 65 with bolts and nuts. The ultrasonic ranging sensor bracket 65 is fixed to the middle of the lower bionic housing 61 with screws. The waterproof camera 66 is used to perform underwater monitoring tasks. The first infrared ranging sensor 67 and the second infrared ranging sensor 68 are used to measure the distance to obstacles in front. The ultrasonic ranging sensor 69 is used to measure the distance of the bionic fish from the bottom of the water.

[0073] The buoyancy control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity, as described in this invention, includes the following steps:

[0074] By combining the buoyancy and center of gravity adjustment devices of the left and right power supply compartments, the center of gravity adjustment auxiliary device of the central compartment, and the left and right flexible pectoral fins, the biomimetic fish's surfacing and diving operations are realized, thereby completing the adjustment to a specified depth, and enabling soft landing and safe start-up underwater.

[0075] The manta ray-like bionic fish uses a depth sensor and an ultrasonic ranging sensor to obtain the current depth d of the manta ray-like bionic fish in real time. t and the current distance D from the bottom of the water t ;

[0076] The initial state of the manta ray-like bionic fish is assumed to be a suspended state. In this state, the positions of the first piston of the first buoyancy center of gravity adjustment device in the left power supply compartment and the second piston of the second buoyancy center of gravity adjustment device in the right power supply compartment are x and x, respectively. l0 and x r0 These correspond to the midpoints of the strokes of the first and second pistons, respectively. The outward pushing direction of the first and second pistons is defined as positive, and the maximum stroke positions are x and x, respectively. l0 +x max and x r0 +x max The minimum positions of the travel distances are x l0 -x max and x r0 -x max The lithium battery pack of the center of gravity adjustment auxiliary device is located at position x. a0 x a0Corresponding to the middle position of the first lithium battery pack's travel distance, the forward movement of the lithium battery pack is defined as the positive direction, and the maximum travel position is x. a0 +x amax The minimum position of the journey is x a0 -x amax The flexible pectoral fins are in their initial horizontal position, and the current buoyancy f of the manta ray-like bionic fish is... 浮 Equal to the current gravity G;

[0077] The manta ray-like bionic fish uses a depth sensor and an ultrasonic ranging sensor to obtain the current depth d of the manta ray-like bionic fish in real time. t and the current distance D from the bottom of the water t The preset target depth is d. tar ;

[0078] like Figure 12 As shown, based on the difference d between the target depth and the current depth tar -d t Divided into surfacing missions and diving missions, (d tar -d t When ) < 0, the ascent task is executed. tar -d t The dive mission will be executed when the 0 value is greater than 0.

[0079] This invention divides the manta ray-like bionic fish diving control method into a rapid diving phase, a slow gliding diving phase, a target approach fine-tuning ascent phase, and a target depth arrival phase. The ascent control method is divided into a rapid ascent phase, a slow gliding ascent phase, a target approach fine-tuning ascent phase, and a target depth arrival phase. Distance thresholds ε1, ε2, and ε3 are defined, where ε1 is the distance threshold for the manta ray-like bionic fish switching from the rapid diving phase to the slow gliding diving phase or from the rapid ascent phase to the slow gliding ascent phase when performing a diving or ascent task; ε2 is the distance threshold for the manta ray-like bionic fish switching from the slow gliding diving phase to the target approach fine-tuning diving phase or from the slow gliding ascent phase to the target approach fine-tuning ascent phase; and ε3 is the distance threshold for the manta ray-like bionic fish switching from the target approach fine-tuning diving phase or the target approach fine-tuning ascent phase to the target depth arrival phase. The difference between the target depth and the current depth, |d|, is used to determine the distance. tar -d t The distance is compared with the target depth thresholds ε1, ε2, and ε3, and then different ascent or descent phases are switched, respectively, as shown by |d. tar -d t |≥ε1、ε1>|d tar -d t |≥ε2、ε2>|d tar -d t |≥ε3 and d tar -dt |<ε3.

[0080] like Figure 15 As shown, the present invention relates to a phase oscillator-based CPG controller for controlling the movement of the left and right flexible pectoral fins of a manta ray-like bionic fish; the CPG controller includes four CPG control units, two of which are located on the left pectoral fin and the other two on the right pectoral fin; the CPG model is as follows:

[0081]

[0082] Among them, a i b i and x i Let A represent the amplitude, offset, and phase of the i-th oscillator; i = 1, 2, 3, 4 are the phase oscillators corresponding to the left rear, left front, right rear, and right front servo motors of the manta ray bionic fish, respectively; i With B i These represent the expected amplitude and expected offset of the i-th oscillator, respectively; α i With β i The convergence coefficients for amplitude and offset, respectively, determine the state variable a. i and b i Convergence speed; f i The oscillation frequency is μ. ij The coupling coefficient between the i-th oscillator and the j-th oscillator determines the strength of the coupling between the corresponding oscillators. θ represents the phase difference between the i-th oscillator and the j-th oscillator. i Let θ1, θ2, θ3, and θ4 be the final output angle of the servo motor from the i-th phase oscillator. These phase oscillators in the CPG topology are coupled to each other, simplifying the coupling parameters of the model and reducing the computational complexity. θ1, θ2, θ3, and θ4, as outputs of the CPG network topology, are converted into PWM signals by a pulse width modulation (PWM) generator, causing the servo motor to swing to the specified angle.

[0083] When the difference d between the specified target depth and the current depth tar -d t When it is greater than zero, that is, (d tar -d t When ) > 0, execute the dive mission; first determine the distance |d| between the current depth and the target depth of the manta ray-like bionic fish. tar -d t Is it less than the current depth and the distance from the bottom D? t This means determining whether the target depth is within the maximum diving depth. If the target depth exceeds the maximum diving depth, i.e., |d tar -d t |>D tThen the manta ray-like bionic fish dives to the bottom and soft-lands. At this point, the target depth is equal to the depth of the bottom, i.e., d. tar =D t +d t Then, based on the difference d between the target depth and the current depth... tar -d t The comparison with the target depth thresholds ε1, ε2, and ε3 switches to the corresponding descent phase. If the target depth does not exceed the maximum descent depth, i.e., |d tar -d t |<D t It is directly based on the difference d between the target depth and the current depth. tar -d t | Compare with the target depth thresholds ε1, ε2, and ε3 to switch to the corresponding descent phase.

[0084] When |d tar -d t When |≥ε1, that is, the difference between the target depth and the current depth |d tar -d t When the distance to the target depth threshold ε1 is greater than or equal to the threshold value, the manta ray-like bionic fish enters a rapid descent phase. During this phase, the first and second pistons move linearly from their initial intermediate positions to their minimum travel positions x. l0 -x max and x r0 -x max As the overall displacement is reduced to a minimum, the buoyancy of the manta ray-shaped bionic fish is adjusted from neutral buoyancy to minimum buoyancy. At this point, the buoyancy f 浮 When the force is less than gravity G, the center of gravity shifts forward, and the manta ray-like bionic fish adjusts from a horizontal posture to a head-pointing-to-bottom posture, then dives into the water in this posture. At this time, the manta ray-like bionic fish uses a designed CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i1 Fixed frequency f i1 Amplitude bias B with sum to zero i The flapping motion provides a vertical downward thrust along the direction the manta ray-like bionic fish is pointing, enabling it to dive rapidly until ε1 > |d. tar -d t |≥ε2, the manta ray-like bionic fish enters a slow gliding and diving phase.

[0085] When ε1>|d tar -d tWhen |≥ε2, the manta ray-like bionic fish enters a slow gliding descent phase. During this phase, the CPG controller adjusts the flexible pectoral fins to their initial position. At this time, the position of the lithium battery pack in the center cabin's center-of-gravity adjustment auxiliary device changes from the middle position x as the descent depth increases. a0 Gradually move linearly to the position of minimum travel x a0 -x amax This process is a dynamic adjustment, and the position of the lithium battery pack of the center of gravity adjustment aid during the slow gliding descent phase is defined as x. adown ,

[0086]

[0087] During this process, as the lithium battery pack of the center of gravity adjustment auxiliary device moves backward, the center of gravity of the manta ray-like bionic fish gradually shifts backward, and when |d tar -d t When |=ε2, the position of the lithium battery pack of the center of gravity adjustment auxiliary device is adjusted to the minimum stroke position x. a0 -x amax The manta ray-like bionic fish's center of gravity returns to its initial central position. During this process, its pitch attitude gradually changes from vertical downwards to upwards and finally reaches a horizontal position. Maintaining minimal buoyancy, the manta ray continues to descend. Combining the changes in pitch attitude, the initial velocity provided during the rapid descent phase, and water resistance, the manta ray decelerates downwards and gradually descends to a horizontal position during the slow gliding descent phase, until ε2 > |d|. tar -d t |≥ε1, the manta ray-like bionic fish enters the fine-tuning descent phase as it approaches the target.

[0088] When ε2>|d tar -d t When |≥ε3, the manta ray-like bionic fish enters the target-approaching fine-tuning descent phase. During this phase, the flexible pectoral fins maintain their initial horizontal position. At this time, the first and second pistons move from their minimum stroke positions x... l0 -x max and x r0 -x max Linearly move to the position closest to the minimum travel distance. Trip Location and As the overall displacement increases from its minimum value, the buoyancy of the manta ray-shaped bionic fish also increases from its minimum buoyancy. At this point, the buoyancy f... 浮 Slightly less than the gravitational force G, while linearly moving the position of the lithium battery pack of the center of gravity adjustment assist device to near the minimum travel position. Trip Location The manta ray-like bionic fish maintains its center of gravity in the initial position and slowly descends horizontally until |d tar -d t |<ε3, the manta ray-like bionic fish enters the stage of reaching the target depth.

[0089] When |d tar -d t When | < ε3, the manta ray-like bionic fish enters the target depth stage. At this time, the first and second pistons move linearly to the intermediate position x. l0 and x r0 The position of the lithium battery pack of the center of gravity adjustment auxiliary device is linearly moved to the middle position x. a0 The manta ray-like bionic fish hovers horizontally at the target depth or achieves a soft landing on the seabed, thus completing the mission.

[0090] When the difference d between the specified target depth and the current depth tar -d t When less than zero, that is (d tar -d t When ) < 0, the ascent task is executed; since the manta ray-like bionic fish's large pectoral fins pose a risk of structural damage due to collisions with the surrounding environment when flapping underwater, the current distance D of the manta ray-like bionic fish from the bottom is first determined. t Does it exceed the safe distance ξ from the bottom of the water? If D t If ξ < ξ, then the manta ray-like bionic fish maintains the initial position of its pectoral fins, and the first and second pistons move linearly to near their maximum stroke position. Trip Location and The position of the lithium battery pack in the center of gravity adjustment assist device is linearly moved to near the maximum travel position. Trip Location The manta ray-like bionic fish slowly rises horizontally until it reaches D. t >ξ;

[0091] When D t When the distance exceeds ξ, the manta ray-like bionic fish has exceeded the safe distance from the bottom of the water, and then the difference between the target depth and the current depth is determined by |d. tar -d t |The comparison with the target depth thresholds ε1, ε2, and ε3 switches to the corresponding ascent phase.

[0092] When |d tar -d t When |≥ε1, that is, the difference between the target depth and the current depth |d tar -d tWhen the distance to the target depth threshold ε1 is greater than or equal to the threshold value, the manta ray-like bionic fish enters a rapid ascent phase. During this phase, the first and second pistons move linearly from their initial intermediate positions to their maximum travel position x. l0 +x max and x r0 +x max As the overall displacement increases to its maximum value, the buoyancy of the manta ray-shaped bionic fish is adjusted from neutral buoyancy to maximum buoyancy. At this point, the buoyancy f 浮 When the force exceeds gravity G, the center of gravity shifts backward, and the manta ray-like bionic fish adjusts from a horizontal posture to a head-up, water-facing posture, and floats towards the surface. At this point, the manta ray-like bionic fish utilizes a designed CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i1 Fixed frequency f i1 Amplitude bias B with sum to zero i The flapping motion provides the manta ray-like bionic fish with a vertical upward thrust along the direction its head is pointing, enabling the manta ray-like bionic fish to rise rapidly until ε1 > |d. tar -d t |≥ε2, the manta ray-like bionic fish enters a slow gliding and surfacing phase.

[0093] When ε1>|d tar -d t When |≥ε2, the manta ray-like bionic fish enters a slow gliding ascent phase. During this phase, the pectoral fins adjust to their initial position. At this time, the position of the lithium battery pack of the center-of-gravity adjustment auxiliary device in the central cabin changes from the middle position x as the ascent depth decreases. a0 Gradually move linearly to the position of maximum travel x a0 +x amax This process involves dynamic adjustment. The position of the lithium battery pack in the center of gravity adjustment aid during the slow gliding and ascent phase is defined as x. aup ,

[0094]

[0095] During this process, as the lithium battery pack of the center of gravity adjustment auxiliary device moves forward, the center of gravity of the manta ray-like bionic fish gradually shifts forward, and when |d tar -d t When |=ε2, the position of the lithium battery pack of the center of gravity adjustment auxiliary device is adjusted to the maximum stroke position x. a0 +x amaxThe manta ray-like bionic fish's center of gravity returns to its initial central position. During this process, its pitch attitude gradually changes from vertical upward to downward and eventually reaches a horizontal position. Maintaining maximum buoyancy, the manta ray-like bionic fish continues to rise. Combining the changes in its pitch attitude, the initial velocity provided during the rapid ascent phase, and water resistance, the manta ray-like bionic fish, in its slow gliding and diving phase, decelerates upward and gradually rises to a horizontal position until ε2 > |d|. tar -d t |≥ε3, the manta ray-like bionic fish enters the fine-tuning and surfacing phase as it approaches the target.

[0096] When ε2>|d tar -d t When |≥ε1, the manta ray-like bionic fish enters the approach-target fine-tuning ascent phase. During this phase, the pectoral fins maintain their initial horizontal position, and the first and second pistons move from their maximum stroke positions x... l0 +x max and x r0 +x max Linearly move to the position closest to the maximum travel. Trip Location and As the overall displacement decreases from its maximum value, the buoyancy of the manta ray-shaped bionic fish also decreases from its maximum buoyancy. At this point, the buoyancy f... 浮 Slightly greater than gravity G, while linearly moving the position of the lithium battery pack of the center of gravity adjustment assist device to near the maximum travel position. Trip Location The manta ray-like bionic fish maintains its center of gravity in the initial position and slowly rises horizontally until |d tar -d t |<ε3, the manta ray-like bionic fish enters the stage of reaching the target depth.

[0097] When |d tar -d t When | < ε3, the manta ray-like bionic fish enters the target depth stage. At this time, the first and second pistons move linearly to the intermediate position x. l0 and x r0 The position of the lithium battery pack of the center of gravity adjustment auxiliary device is linearly moved to the middle position x. a0 The manta ray-like bionic fish hovered horizontally at the target depth, mission accomplished.

[0098] The obstacle avoidance control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity, as described in this invention, includes the following steps:

[0099] The obstacle avoidance and steering control method of the highly maneuverable manta ray-like bionic fish is divided into a highly maneuverable large-angle steering mode and a highly maneuverable small-angle steering mode, specifically including a highly maneuverable large-angle left turn mode, a highly maneuverable small-angle left turn mode, a highly maneuverable large-angle right turn mode, and a highly maneuverable small-angle right turn mode. The preset distances to obstacles output by the infrared ranging sensors at the left and right front of the manta ray-like bionic fish are D, respectively. lt and D rt The manta ray-like bionic fish is currently swimming forward at a linear speed of v. t The speed threshold for the manta ray-like bionic fish to perform a high-maneuverability obstacle avoidance and turning task is v1. Distance thresholds dis1 and dis2 are defined, where dis1 is the distance threshold for the manta ray-like bionic fish to enter a high-maneuverability large-angle turning mode, and dis2 is the distance threshold for the manta ray-like bionic fish to enter a high-maneuverability small-angle turning mode. The minimum distance from the current obstacle to the obstacle is min(D). lt D rt The distance to the obstacle is compared with obstacle thresholds dis1 and dis2, and then different high-maneuverability steering modes are switched. The preset parameters of the CPG controller in high-maneuverability obstacle avoidance and steering tasks are a fixed phase difference. Fixed amplitude A i2 Fixed frequency f i2 Dynamically adjust amplitude bias B i The preset maximum amplitude offset is B. imax Amplitude bias B i >0;

[0100] After entering high-maneuverability steering mode, the manta ray-like bionic fish needs to use IMU data to calculate the forward distance, yaw angle, distance to obstacles, and lateral distance deviating from the initial course to determine when to end the high-maneuverability steering mode. The preset safe distance threshold to obstacles is dis. safe The lateral safety distance threshold for deviation from the initial course is dis latsafe The bionic fish enters high-maneuverability turning mode with an initial velocity of v0 and an initial distance of D from the obstacle. obs0 D obs0 =D lt Or D obs0 =D rt The acceleration of the bionic fish at the current moment is a. t Acceleration is provided by the IMU, and the bionic fish travels a distance dis from its initial position after obstacle avoidance. t The current heading angle relative to the initial heading is θ. t The heading angle is provided by the IMU, and the current distance between the bionic fish and the obstacle during the turning process is D. obst The lateral distance that the bionic fish has deviated from its initial course is D. latt ,

[0101] The current swimming speed v1 of the manta ray-like bionic fish is calculated using the following formula:

[0102]

[0103] The distance traveled by a manta ray-like biomimetic fish from its initial position after obstacle avoidance (dis) t Calculated using the following formula:

[0104]

[0105] The current distance D between the manta ray-like bionic fish and the obstacle during the turning process obst Calculated using the following formula:

[0106]

[0107] The lateral distance D of the manta ray-like bionic fish currently deviating from its initial course. latt Calculated using the following formula:

[0108] D latt =dis t sin(θ) t )

[0109] When the swimming speed v t ≥v1 and the minimum distance to the obstacle min(D) lt D rt When )≤dis1, the manta ray-like bionic fish autonomously performs highly maneuverable obstacle avoidance and turning tasks;

[0110] When v t ≥v1 and dis1≥min(D) lt D rt When )≥dis2, if D lt >D rt The manta ray-like bionic fish enters a high-maneuverability, small-angle left-turn mode. In this mode, the first piston on the left moves linearly from its initial middle position to its minimum stroke position x. l0 -x max The second piston on the right moves linearly from its initial middle position to its maximum stroke position x. r0 +x max The manta ray-shaped bionic fish maintains balance in the forward and backward direction, while its center of buoyancy shifts to the right in the left and right direction. The manta ray-shaped bionic fish then rolls 90° to the left, assuming a vertical orientation with the right pectoral fin pointing upwards. At this point, the buoyancy of the manta ray-shaped bionic fish equals its weight. Simultaneously, the manta ray-shaped bionic fish utilizes a CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i2 Fixed frequency f i2Sum of values The amplitude offset flapping provides the manta ray-like bionic fish with the torque to turn left, enabling the manta ray-like bionic fish to make a high-maneuverability small-angle left turn in three-dimensional space, thereby avoiding obstacles on the right.

[0111] When the current distance between the manta ray-like bionic fish and the obstacle is D obst The distance is greater than the safe distance threshold from the obstacle. safe And the current lateral distance deviating from the initial heading is D. latt The lateral safety distance threshold greater than the deviation from the initial heading is dis latsafe D obst >dis safe And D latt >dis latsafe At this time, the first and second pistons are adjusted to the initial middle position, the pectoral fins are adjusted to the initial zero position, the buoyancy center of the manta ray-like bionic fish returns to the center position in the left and right directions, the manta ray-like bionic fish rolls to the right to a horizontal attitude, the high-maneuverability obstacle avoidance mission is completed, and the cruise mission continues.

[0112] When v t ≥v1 and min(D) lt D rt When ) < dis2, if D lt >D rt The manta ray-like bionic fish enters a high-mobility, large-angle left-turn mode. In this mode, the first piston on the left moves linearly from its initial middle position to its minimum stroke position x. l0 -x max The second piston on the right moves linearly from its initial middle position to its maximum stroke position x. r0 +x max The manta ray-shaped bionic fish maintains balance in the forward and backward direction, while its center of buoyancy shifts to the right in the left and right direction. The manta ray-shaped bionic fish then rolls 90° to the left, assuming a vertical orientation with the right pectoral fin pointing upwards. At this point, the buoyancy of the manta ray-shaped bionic fish equals its weight. Simultaneously, the manta ray-shaped bionic fish utilizes a CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i2 Fixed frequency f i2 The sum is B imax The amplitude offset flapping provides the manta ray-like bionic fish with a larger torque for turning left, enabling it to make highly maneuverable, large-angle left turns in three-dimensional space, thus avoiding obstacles on the right; when the current distance between the manta ray-like bionic fish and the obstacle is D... obst The distance is greater than the safe distance threshold from the obstacle. safe And the current lateral distance deviating from the initial heading is D. lattThe lateral safety distance threshold greater than the deviation from the initial heading is dis latsafe D obst >dis safe And D latt >dis latsafe At this time, the first and second pistons are adjusted to the initial middle position, the pectoral fins are adjusted to the initial zero position, the buoyancy center of the manta ray-like bionic fish returns to the center position in the left and right directions, the manta ray-like bionic fish rolls to the right to a horizontal attitude, the high-maneuverability obstacle avoidance mission is completed, and the cruise mission continues.

[0113] When v t ≥v1 and dis1≥min(D) lt D rt When )≥dis2, if D lt <D rt The manta ray-like bionic fish enters a high-maneuverability, small-angle right turn mode. In this mode, the first piston on the left moves linearly from its initial middle position to its maximum stroke position x. l0 +x max The second piston on the right moves linearly from its initial middle position to its minimum stroke position x. r0 -x max The manta ray-shaped bionic fish maintains balance in the forward and backward direction, while its center of buoyancy shifts to the left in the left and right direction. The manta ray-shaped bionic fish then rolls 90° to the right, assuming a vertical orientation with the left pectoral fin pointing upwards. At this point, the buoyancy of the manta ray-shaped bionic fish equals its weight. Simultaneously, the manta ray-shaped bionic fish utilizes a CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i2 Fixed frequency f i2 Sum of values The amplitude offset flapping motion provides the manta ray-like bionic fish with a right-turning torque, enabling it to achieve highly maneuverable, small-angle right turns in three-dimensional space, thus avoiding obstacles on the left; when the current distance between the manta ray-like bionic fish and the obstacle is D... obst The distance is greater than the safe distance threshold from the obstacle. safe And the current lateral distance deviating from the initial heading is D. latt The lateral safety distance threshold greater than the deviation from the initial heading is dis latsafe D obst >dis safe And D latt >dis latsafe At this time, the first and second pistons are adjusted to the initial middle position, the pectoral fins are adjusted to the initial zero position, the buoyancy center of the manta ray-like bionic fish returns to the center position in the left and right directions, the manta ray-like bionic fish rolls to the left to a horizontal attitude, the high-maneuverability obstacle avoidance mission is completed, and the cruise mission continues.

[0114] When v t ≥v1 and min(D) lt D rt When ) < dis2, if D lt <D rt The manta ray-like bionic fish enters a high-mobility, large-angle right-turn mode. In this mode, the first piston on the left moves linearly from its initial middle position to its maximum stroke position x. l0 +x max The second piston on the right moves linearly from its initial middle position to its minimum stroke position x. r0 -x max The manta ray-shaped bionic fish maintains balance in the forward and backward direction, while its center of buoyancy shifts to the left in the left and right direction. The manta ray-shaped bionic fish then rolls 90° to the right, assuming a vertical orientation with the left pectoral fin pointing upwards. At this point, the buoyancy of the manta ray-shaped bionic fish equals its weight. Simultaneously, the manta ray-shaped bionic fish utilizes a CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i2 Fixed frequency f i2 The sum is B imax The amplitude offset flapping provides a larger right-turning torque for the manta ray-like bionic fish, enabling it to achieve high maneuverability and large-angle right turns in three-dimensional space, thus avoiding obstacles on the left; when the current distance between the manta ray-like bionic fish and the obstacle is D... obst The distance is greater than the safe distance threshold from the obstacle. safe And the current lateral distance deviating from the initial heading is D. latt The lateral safety distance threshold greater than the deviation from the initial heading is dis latsafe D obst >dis safe And D latt >dis latsafe At this time, the first and second pistons are adjusted to the initial middle position, the pectoral fins are adjusted to the initial zero position, the buoyancy center of the manta ray-like bionic fish returns to the center position in the left and right directions, the manta ray-like bionic fish rolls to the left to a horizontal attitude, the high-maneuverability obstacle avoidance mission is completed, and the cruise mission continues.

Claims

1. A method for controlling the buoyancy and dive of a highly maneuverable manta ray-like biomimetic fish based on the combined adjustment of buoyancy and center of gravity, characterized in that, The biomimetic fish includes a base and pectoral fins. The base comprises a biomimetic shell (6), a central chamber (1), and power supply chambers symmetrically arranged on both sides of the central chamber. The central chamber (1) is a sealed structure. A center of gravity adjustment auxiliary device (11) of the central chamber (1) is slidably disposed near the head of the biomimetic fish to change the center of gravity position of the central chamber and control the pitch angle of the head. The power supply chamber includes a sealing flange, a chamber body, a buoyancy center of gravity adjustment device, and an inlet / drainage flange. The sealing flange, chamber body, and buoyancy center of gravity adjustment device form a sealed structure. The buoyancy center of gravity adjustment device is slidably disposed near the tail of the biomimetic fish to change the drainage volume on one side of the buoyancy center of gravity adjustment device and the inlet / drainage flange, thereby controlling the buoyancy and center of gravity position of the power supply chamber. The biomimetic shell (6) is provided with inlet / drainage ports. The submersion control method includes the following steps: The initial state of the manta ray-like bionic fish is assumed to be a suspended state. In this state, the piston positions of the buoyancy and center of gravity adjustment devices located on the left and right sides of the central cabin are x, respectively. l0 and x r0 The position corresponding to the middle of the piston stroke is defined as the positive direction when the piston pushes outward, and the maximum stroke positions are x and x. l0 +x max and x r0 +x max The minimum positions of the travel distances are x l0 -x max and x r0 -x max The lithium battery pack of the center of gravity adjustment auxiliary device is located at position x. a0 x a0 Corresponding to the middle position of the first lithium battery pack's travel distance, the forward movement of the lithium battery pack is defined as the positive direction, and the maximum travel position is x. a0 +x amax The minimum position of the journey is x a0 -x amax The flexible pectoral fins are in their initial horizontal position, and the current buoyancy f of the manta ray-like bionic fish is... 浮 Equal to the current gravity G; The pectoral fins are controlled by two CPG control units; the CPG model is... Among them, a i b i and x i Let A represent the amplitude, offset, and phase of the i-th oscillator; i = 1, 2, 3, 4 are the phase oscillators corresponding to the left rear, left front, right rear, and right front servo motors of the manta ray bionic fish, respectively; i With B i These represent the expected amplitude and expected offset of the i-th oscillator, respectively; α i With β i These are the convergence coefficients for amplitude and offset, respectively; f i The oscillation frequency is μ. ij x is the coupling coefficient between the i-th oscillator and the j-th oscillator; j The current phase of the j-th oscillator; θ represents the phase difference between the i-th oscillator and the j-th oscillator. i Let be the servo angle output by the i-th phase oscillator; Define distance-to-target depth thresholds ε1, ε2, and ε3, where ε1 is the distance-to-target depth threshold when the manta ray bionic fish switches from a rapid descent phase to a slow gliding descent phase or from a rapid ascent phase to a slow gliding ascent phase when performing a dive or ascent mission; ε2 is the distance-to-target depth threshold when the manta ray bionic fish switches from a slow gliding descent phase to a near-target fine-tuning descent phase or from a slow gliding ascent phase to a near-target fine-tuning ascent phase; and ε3 is the distance-to-target depth threshold when the manta ray bionic fish switches from a near-target fine-tuning descent phase or a near-target fine-tuning ascent phase to the target depth. Through the target depth d tar With current depth d t The difference in magnitude |d tar -d t | Compare with the target depth thresholds ε1, ε2, and ε3, and then switch to different surfacing or descent phases.

2. The buoyancy control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity as described in claim 1, characterized in that, When (d) tar -d t When ) > 0, execute the dive mission; When |d tar -d t When |≥ε1, the rapid descent phase begins. The piston moves linearly from the initial middle position to the minimum stroke position, the displacement decreases to its minimum value, and the buoyancy of the manta ray-like bionic fish is adjusted from neutral buoyancy to minimum buoyancy. At this time, the buoyancy f 浮 When the gravitational force is less than G, the center of gravity shifts forward, and the manta ray-like biomimetic fish adjusts from a horizontal posture to a head-pointing-to-bottom posture, and dives towards the bottom in this posture, with the pectoral fins maintaining a fixed phase difference forward and backward. Fixed amplitude A i1 Fixed frequency f i1 Amplitude bias B with sum to zero i The flapping motion provides a vertical downward thrust along the direction the manta ray-like bionic fish is pointing, enabling it to dive rapidly until ε1 > |d. tar -d t |≥ε2; When ε1>|d tar -d t When |≥ε2, the system enters a slow gliding descent phase. The CPG controller adjusts the pectoral fins to their initial positions, and the lithium battery pack of the center capsule's center of gravity adjustment auxiliary device is positioned at x. adown for The center of gravity of the manta ray-like biomimetic fish gradually shifts backward, and when |d tar -d t When |=ε2, the position of the lithium battery pack of the center of gravity adjustment auxiliary device is adjusted to the minimum stroke position x. a0 -x amax The manta ray-like bionic fish's center of gravity returns to its initial central position. During this process, the manta ray-like bionic fish's pitch attitude changes from vertical downwards and upwards, eventually reaching a horizontal attitude. Maintaining minimal buoyancy, the manta ray-like bionic fish continues to descend. In the slow gliding descent phase, it decelerates downwards and gradually descends to a horizontal attitude until ε2 > |d. tar -d t |≥ε1; When ε2>|d tar -d t When |≥ε3, the target fine-tuning descent phase begins. The pectoral fins maintain their initial horizontal position, and the pistons move linearly from their minimum stroke position to a position close to their minimum stroke position. The stroke position; simultaneously, the position of the lithium battery pack of the center of gravity adjustment assist device is linearly moved to the position closest to the minimum stroke position. During the flight, the manta ray-like bionic fish maintains its center of gravity in the initial position and slowly descends in a horizontal posture until |d tar -d t |<ε3; When |d tar -d t When | < ε3, the target depth stage begins. The piston moves to the middle position, and the lithium battery pack of the center of gravity adjustment auxiliary device moves linearly to the middle position. The manta ray-like bionic fish hovers at the target depth in a horizontal posture or achieves a soft landing on the seabed, and the mission is completed.

3. The buoyancy control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity as described in claim 1, characterized in that, Immediately (d) tar -d t When ) < 0, determine the current distance D of the manta ray-like bionic fish from the bottom of the water. t Is the safe distance from the bottom of the water exceeded? If D t If ξ < ξ, then the manta ray-like bionic fish maintains the initial position of its pectoral fins, and the piston moves linearly to near its maximum stroke position. The stroke position linearly moves the position of the lithium battery pack of the center of gravity adjustment assist device to near the maximum stroke position. At the destination, the manta ray-like bionic fish slowly rises horizontally until it reaches position D. t >ξ; When D t When the distance exceeds ξ, the manta ray-like bionic fish has exceeded the safe distance from the bottom of the water and is about to rise to the surface. When |d tar -d t When |≥ε1, the rapid ascent phase begins, and the piston moves linearly from the middle position to the maximum stroke position. The buoyancy of the manta ray-like bionic fish is adjusted from neutral buoyancy to maximum buoyancy, at which point the buoyancy f 浮 When the force exceeds gravity G, the center of gravity shifts backward, and the manta ray-like bionic fish adjusts from a horizontal posture to a head-up, water-facing posture, and floats towards the surface. At this point, the manta ray-like bionic fish utilizes a designed CPG controller based on a phase oscillator to achieve a fixed phase difference between the flexible pectoral fins. Fixed amplitude A i1 Fixed frequency f i1 Amplitude bias B with sum to zero i The flapping motion provides the manta ray-like bionic fish with a vertical upward thrust along the direction its head is pointing, enabling the manta ray-like bionic fish to rise rapidly until ε1 > |d. tar -d t |≥ε2; When ε1>|d tar -d t When |≥ε2, enter the slow gliding ascent phase, pectoral fins are adjusted to their initial positions, and the position of the lithium battery pack of the center capsule's center of gravity adjustment auxiliary device is x. aup for During this process, the center of gravity of the manta ray-like bionic fish gradually shifts forward, and when |d tar -d t When |=ε2, the position of the lithium battery pack of the center of gravity adjustment auxiliary device is adjusted to the maximum stroke position x. a0 +x amax The manta ray-like bionic fish's center of gravity returns to its initial central position. During this process, the manta ray-like bionic fish's pitch attitude gradually changes from vertical upward to downward and finally reaches a horizontal attitude. Meanwhile, the manta ray-like bionic fish maintains maximum buoyancy and continues to rise, decelerating upward and gliding until it gradually rises to a horizontal attitude, until ε2>|d tar -d t |≥ε1; When ε2>|d tar -d t When |≥ε1, the system enters the fine-tuning and upward movement phase close to the target. The pectoral fins maintain their initial horizontal position, and the piston moves linearly from its maximum stroke position to a position close to its maximum stroke position. Simultaneously, the position of the lithium battery pack of the center of gravity adjustment assist device is linearly moved to near the maximum stroke position. During its journey, the manta ray-like bionic fish maintains its center of gravity in the initial position and slowly rises horizontally until |d tar -d t |<ε3; When |d tar -d t When | < ε3, the target depth stage begins. The piston moves linearly to the middle position, the lithium battery pack of the center of gravity adjustment auxiliary device moves linearly to the middle position, and the manta ray-like bionic fish hovers at the target depth in a horizontal posture, completing the mission.

4. The buoyancy control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity as described in claim 1, characterized in that, The center of gravity adjustment auxiliary device (11) includes a sealed chamber flange (111), a linear servo and a counterweight unit. The counterweight unit is located inside the sealed chamber flange (111). The linear servo is installed on the outside of the sealed chamber flange (111) through a connecting plate and a bracket. The telescopic rod of the linear servo is connected to the counterweight unit to control the position of the counterweight unit.

5. The buoyancy control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity as described in claim 4, characterized in that, The counterweight unit includes a first lithium battery pack (118), a fixed support, and a mounting plate. The fixed support and the mounting plate are connected by a connecting rod, and the first lithium battery pack (118) is mounted on the fixed support.

6. The buoyancy control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity as described in claim 1, characterized in that, The central compartment (1) also includes a control system (12), a central compartment intermediate body (13), a central compartment rear sealing flange (14), and a central compartment rear end cover (15).

7. The buoyancy control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity as described in claim 1, characterized in that, The buoyancy center of gravity adjustment device includes a linear servo, a second lithium battery pack (447), a piston, and a piston seal.

8. The buoyancy control method for a highly maneuverable manta ray-like bionic fish based on the combined adjustment of buoyancy and center of gravity as described in claim 1, characterized in that, Digital servos are installed at both ends of the power supply compartment, and the pectoral fins are connected to the digital servos via fin rays and connecting brackets; each digital servo is equipped with a CPG control unit.

Images