Underwater docking method of bionic robotic fish based on pectoral fin submersible structure

Abstract

A method for underwater docking of a bionic robotic fish based on a pectoral fin lifting and diving structure controls the vertical ascent or descent of the bionic robotic fish by leveraging the resistance differential perpendicular to the pectoral fin surface generated during the upward and downward swinging of the pectoral fins. During docking, the bionic robotic fish is controlled to rise vertically to the bottom of an underwater vehicle and further generate a preload force. This ensures that the bionic robotic fish's vacuum suction cup fully contacts the bottom of the underwater vehicle, after which the water within the vacuum suction cup is expelled to achieve underwater docking. During detachment, water is injected into the vacuum suction cup to eliminate the internal and external pressure differential, and the bionic robotic fish is controlled to descend vertically, achieving detachment from the underwater vehicle. This method offers simple control, low energy consumption, and strong adaptability.

Description

Technical Field

[0001] The present invention relates to a technology in the field of bionic mechanical control, in particular to an underwater docking method for a bionic robotic fish based on a pectoral fin lifting and diving structure. Background Art

[0002] Existing underwater recovery methods primarily rely on docking, which can be categorized as capture-type docking, using ropes and rods as docking targets; containment-type docking, using conical guide hoods and cages as docking targets; and seated-type docking, using underwater platforms as docking targets. These three docking methods are designed for underwater unmanned vehicles and have low adaptability to bionic robotic fish. This is primarily due to the following: while these underwater docking methods can achieve docking with bionic robotic fish, they all suffer from the disadvantages of being easily affected by ocean currents, having complex equipment, and requiring significant modifications to the bionic robotic fish. The existing technology lacks a specific underwater docking method specifically designed for bionic robotic fish. Summary of the Invention

[0003] In response to the shortcomings of existing technologies that cannot achieve vertical ascent and descent and cannot provide sufficient pre-tightening force for adsorption, the present invention proposes a bionic robotic fish underwater docking method based on the pectoral fin ascent and descent structure. This method has simple control, low energy consumption and strong adaptability.

[0004] The present invention is achieved through the following technical solutions:

[0005] The present invention relates to an underwater docking method for a bionic robotic fish based on a pectoral fin lifting and diving structure. The method controls the vertical ascent or descent of the bionic robotic fish by utilizing the resistance difference perpendicular to the pectoral fin surface generated during the up and down swinging of the pectoral fin. During docking, the bionic robotic fish is controlled to vertically ascend to the bottom of an underwater vehicle and further generate a pre-tightening force, so that after the vacuum suction cup of the bionic robotic fish fully contacts the bottom of the underwater vehicle, the water in the vacuum suction cup is discharged to achieve underwater docking. During detachment, water is injected into the vacuum suction cup to eliminate the internal and external pressure difference and the bionic robotic fish is controlled to vertically descend, thereby achieving detachment of the bionic robotic fish from the underwater vehicle.

[0006] The bionic robotic fish is provided with: an adsorption device for providing suction and a pectoral fin lifting and diving device for providing vertical lifting potential, wherein: the adsorption device and the pectoral fin lifting and diving structure are distributed up and down, and the two cooperate to achieve the adsorption and detachment of the bionic robotic fish.

[0007] The drag differential perpendicular to the pectoral fin surface refers to the following: when the pectoral fin's upward swing (upstroke) and downward swing (downstroke) have different speeds, the forces perpendicular to the pectoral fin surface generated during the upstroke and downstroke are decomposed into vertical and horizontal forces. The horizontal forces cancel each other out, and the vertical force acts as the lift potential. Specifically, when the downstroke speed is greater than the upstroke speed, the resultant force of the pectoral fins in a cycle is the upward buoyancy force, achieving vertical ascent; when the downstroke speed is less than the upstroke speed, the resultant force of the pectoral fins in a cycle is the downward force, achieving vertical descent.

[0008] Technical Effects

[0009] The present invention adopts a pectoral fin lifting and diving structure based on flapping wing theory and a vacuum suction cup adsorption method. The control is simple, and the underwater docking of the bionic robotic fish can be achieved by controlling only a water pump and two servo motors; only a small power is required to drive the water pump to maintain the adsorption action, and the bionic robotic fish is adsorbed on the docking platform and follows the movement of the platform, which can greatly reduce the energy consumption of the bionic robotic fish during underwater work, so that the bionic robotic fish can cooperate with the ocean vehicle to better complete the corresponding work tasks; the adaptability is strong, and the device can be applied to most bionic robotic fish without the need for major modifications to the bionic robotic fish. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of a bionic robotic fish according to an embodiment;

[0011] Figure 2 This is a schematic diagram of the pectoral fin diving device;

[0012] Figure 3 A schematic diagram of a vertical dive in an embodiment;

[0013] Figure 4 A schematic diagram of vertical floating in an embodiment;

[0014] Figure 5 Schematic diagram of the adsorption device;

[0015] Figure 6 Schematic diagram of underwater docking method according to an embodiment;

[0016] Among them: 1 vacuum suction cup, 2 suction cup connecting pipe, 3 water pump, 4 pectoral fin servo bracket, 5 pectoral fin servo, 6 left pectoral fin, 7 pectoral fin connector, 8 right pectoral fin, 9 bionic remora, 10 adsorption device, 11 pectoral fin lifting and diving structure. DETAILED DESCRIPTION

[0017] This embodiment relates to a method for underwater docking of a bionic robotic fish based on a pectoral fin lifting and diving structure. The bionic robotic fish is controlled to rise or fall vertically by using the resistance difference perpendicular to the pectoral fin surface generated during the up and down swinging of the pectoral fin. During docking, the bionic robotic fish is controlled to rise vertically to the bottom of the underwater vehicle and further generate a pre-tightening force. After the vacuum suction cup of the bionic robotic fish fully contacts the bottom of the underwater vehicle, the water in the vacuum suction cup is discharged to achieve underwater docking. During detachment, water is injected into the vacuum suction cup to eliminate the internal and external pressure difference and the bionic robotic fish is controlled to descend vertically, thereby achieving detachment of the bionic robotic fish from the underwater vehicle.

[0018] like Figure 1 As shown, the bionic robotic fish 9 is provided with: an adsorption device 10 and a pectoral fin lifting and diving device 11, wherein: the adsorption device 10 and the pectoral fin lifting and diving structure 11 are distributed up and down, the pectoral fin lifting and diving structure 11 can realize the vertical lifting and diving of the bionic robotic fish, and the adsorption device provides suction, and the two cooperate to realize the adsorption and detachment of the bionic robotic fish.

[0019] like Figure 3 , Figure 4 As shown, the resistance difference perpendicular to the pectoral fin surface means that: when the pectoral fin swings upward, that is, the upstroke, and swings downward, that is, the speed of the downstroke, are different, the forces of different sizes perpendicular to the pectoral fin surface generated in the upstroke and downstroke are mechanically decomposed to obtain the vertical force. Specifically: when the speed of the downstroke is greater than the upstroke, the resultant force of the pectoral fin in one cycle is the buoyancy force, realizing vertical ascent; when the speed of the downstroke is less than the upstroke, the resultant force of the pectoral fin in one cycle is the descending force, realizing vertical descent.

[0020] like Figure 2 As shown, the pectoral fin diving device 11 includes: a pectoral fin servo gear bracket 4 provided in the bionic robotic fish 9 and a pair of pectoral fin servos 5 fixed thereon, wherein the pectoral fin servos 5 are respectively connected to the left and right pectoral fins 6 and 8 through corresponding pectoral fin connectors 7. The motion law of the pectoral fin servos 5 in one cycle satisfies:

[0021] When descending, the pectoral fin servo angle

[0022] When ascending, the pectoral fin servo angle

[0023] Among them: A max is the maximum amplitude of the pectoral fin swing, ω fast is the faster angular velocity of the pectoral fin, ω slow is the slower angular velocity of the pectoral fin, t up is the time of the pectoral fin upstroke in one swing cycle, t down is the time of the pectoral fin downstroke in one swing cycle, t total The time for one oscillation cycle of the pectoral fin.

[0024] The pectoral fin servo 5 is a waterproof digital servo, and its output angle law is a sine function, which drives the pectoral fin to perform fan-shaped motion in the vertical plane around the output axis of the pectoral fin servo 5.

[0025] One end of the pectoral fin connector 7 is circular and the other end is square, and the square end is connected to the left pectoral fin 6 and the right pectoral fin 8 respectively.

[0026] The left pectoral fin 6 and the right pectoral fin 8 are based on the pectoral fin of remora, have a larger area, and can generate greater buoyancy and downward force.

[0027] like Figure 3 As shown, the adsorption device includes: a vacuum suction cup 1, a suction cup connecting pipe 2 and a water pump 3 connected in sequence, wherein: the vacuum suction cup 1 is an elliptical double-layer flexible suction cup with two layers of cavity inside, and the inner plane of the cavity has protruding small square columns to increase the adsorption force.

[0028] The bottom of the vacuum suction cup 1 has a circular opening, which can be fixed to the top of the bionic robotic fish and connected to the suction cup connecting tube 2.

[0029] The water pump 3 is cylindrical in shape, with a cylindrical water inlet on the top and a cylindrical outlet with a slightly smaller diameter on the side of the cylinder. The internal motor works to achieve one-way drainage. The maximum flow rate can reach 2.5L / min.

[0030] The suction cup connecting pipe 2 is a flexible circular plastic hose.

[0031] The suction force generated by the vacuum suction cup 1 is related to the area and vacuum degree of the vacuum suction cup 1. The maximum vacuum degree of the vacuum suction cup 1 is P = 0.03Mpa, and the area is S = 9800mm. 2 , the maximum suction force F that the vacuum cup 1 can provide max =P×S=294N.

[0032] After specific actual experiments, in a 5m long, 2m wide and 3m deep still water pool environment, the A max =40 ° ,ω fast =2πrad / s,ω slow The above device was operated with the following parameters: πrad / s, and a pump head of 2.5 L / min. The experimental data obtained showed that the bionic robotic fish floated from the bottom of the pool to the bottom of an underwater vehicle in ten seconds. When its pectoral fins performed a downward movement, it successfully attached to the underwater vehicle, achieving underwater docking between the bionic robotic fish and the underwater vehicle. The pump then stopped, and the pectoral fins performed a downward movement, completing the detachment of the bionic robotic fish. During the docking, a tensile force gauge was used to apply a tensile force to the underwater vehicle, and the bionic robotic fish detached at 290 N.

[0033] Compared to existing technologies, the present invention utilizes a vacuum suction cup-based suction method, resulting in high suction force and simple control. A pectoral fin lift structure based on flapping wing theory generates lift force through the varying up and down swing frequencies of the pectoral fins, achieving vertical lift and providing preload for suction cup docking. This underwater docking method, combining a pectoral fin lift structure with a vacuum suction cup, not only offers high docking reliability but also strong adaptability, eliminating the need for major modifications to the bionic robotic fish and making it suitable for underwater docking with existing small and medium-sized bionic robotic fish.

[0034] The above-mentioned specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principles and purpose of the present invention. The scope of protection of the present invention shall be based on the claims and shall not be limited by the above-mentioned specific implementation. All implementation schemes within its scope shall be subject to the constraints of the present invention.

Claims

1. A method for underwater docking of a bionic robotic fish based on a pectoral fin submersible structure, characterized in that: The bionic robotic fish is controlled to rise or fall vertically by using the resistance difference perpendicular to the pectoral fin surface generated during the up and down swinging of the pectoral fins. During docking, the bionic robotic fish is controlled to rise vertically to the bottom of the underwater vehicle and further generate a pre-tightening force, so that the vacuum suction cup of the bionic robotic fish fully contacts the bottom of the underwater vehicle, and then the water in the vacuum suction cup is discharged to achieve underwater docking. During detachment, water is injected into the vacuum suction cup to eliminate the internal and external pressure difference and control the bionic robotic fish to descend vertically, thereby achieving detachment of the bionic robotic fish from the underwater vehicle. The drag difference perpendicular to the pectoral fin surface refers to: when the pectoral fin swings upward, that is, the upstroke, and swings downward, that is, the downstroke, at different speeds, the forces perpendicular to the pectoral fin surface generated in the upstroke and downstroke are decomposed into vertical and horizontal forces, the horizontal forces cancel each other out, and the vertical force acts as the lifting potential. When the speed of the downstroke is greater than the upstroke, the resultant force of the pectoral fin in one cycle is the buoyancy force, achieving vertical ascent; when the speed of the downstroke is less than the upstroke, the resultant force of the pectoral fin in one cycle is the descending force, achieving vertical descent. The bionic robotic fish is provided with: an adsorption device for providing suction and a pectoral fin submersible device for providing vertical lifting potential, wherein: the adsorption device and the pectoral fin submersible device are distributed vertically, and the combination of the two can realize the adsorption and detachment of the bionic robotic fish; The pectoral fin submersible device comprises: a pectoral fin servo bracket provided in the bionic robotic fish and a pair of pectoral fin servos fixed thereon, wherein the pectoral fin servos are respectively connected to the left pectoral fin and the right pectoral fin via corresponding pectoral fin connectors; The pectoral fin servo's motion pattern in one cycle satisfies: When descending, the pectoral fin servo angle ; When ascending, the pectoral fin servo angle , in: is the maximum amplitude of the pectoral fin swing, is the faster angular velocity of the pectoral fin, is the slower angular velocity of the pectoral fin, is the time of the pectoral fin upstroke in one swing cycle, is the time of the pectoral fin downstroke in one swing cycle, The time for one oscillation cycle of the pectoral fin.

2. The underwater docking method of a bionic robotic fish based on a pectoral fin submersible structure according to claim 1 is characterized in that: The pectoral fin servo is a waterproof digital servo, and its output angle law is a sine function, which drives the pectoral fin to perform fan-shaped motion in a vertical plane around the pectoral fin servo output shaft.

3. The underwater docking method of a bionic robotic fish based on a pectoral fin submersible structure according to claim 1 is characterized in that: One end of the pectoral fin connector is circular, and the other end is square, and the square end is respectively connected to the left pectoral fin and the right pectoral fin.

4. The underwater docking method of a bionic robotic fish based on a pectoral fin submersible structure according to claim 1 or 3, characterized in that: The left pectoral fin and the right pectoral fin are based on the pectoral fin of remora to generate greater buoyancy and descending force.

5. The underwater docking method of a bionic robotic fish based on a pectoral fin submersible structure according to claim 1 is characterized in that: The adsorption device includes: a vacuum suction cup, a suction cup connecting pipe and a water pump connected in sequence, wherein the vacuum suction cup is an elliptical double-layer flexible suction cup with two layers of cavity inside, and the inner plane of the cavity has protruding small square columns to increase the adsorption force.

6. The underwater docking method of a bionic robotic fish based on a pectoral fin submersible structure according to claim 5 is characterized by: The bottom of the vacuum suction cup is provided with a circular opening for being fixed to the top of the bionic robotic fish and connected to the suction cup connecting pipe.

7. The underwater docking method of a bionic robotic fish based on a pectoral fin submersible structure according to claim 5 is characterized by: The water pump is cylindrical in structure, with a cylindrical water inlet on the top and a cylindrical water outlet with a slightly smaller diameter on the side of the cylinder, and one-way drainage is achieved through the operation of an internal motor.

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