A rigid-flexible coupled bionic robotic fish that mimics fish snorkeling

Abstract

The present invention discloses a rigid-flexible coupling bionic robotic fish that mimics fish swim bladder snorkeling, relating to the field of bionic technology. The invention comprises an SMA flexible tail fin, an electromagnetically driven pectoral fin, a fish swim bladder mimicking mechanism, a MOS transistor, and a power supply. The SMA flexible tail fin is used to achieve variable stiffness of the bionic robotic fish's tail fin; the fish swim bladder mimicking mechanism is used to enable the bionic robotic fish to snorkel; the electromagnetically driven pectoral fin is used to enable the bionic robotic fish to move straight and turn; the MOS transistor is used as an electronic switch to control the on and off of each branch circuit; and the power supply is used to supply energy to the bionic robotic fish. The present invention can effectively achieve variable stiffness and flexible swinging of the bionic robotic fish's tail fin, effectively solving the problem of slow cooling of SMA wire. The electromagnetically driven pectoral fin improves the maneuverability of the BCF robotic fish while also reducing the complexity of the mechanism. The fish swim bladder mimicking snorkeling mechanism has the advantages of small size and light weight compared to the center of gravity adjustment mechanism. In summary, the bionic robotic fish has good motion performance.

Description

Technical Field

[0001] The present invention relates to the fields of underwater robot technology, bionic technology, and in particular to a rigid-flexible coupling bionic robotic fish that imitates fish bladder snorkeling. Background Art

[0002] With the rapid development of disciplines such as mechanics, electronics, and bionics, soft robots are demonstrating advantages over traditional rigid robots in applications such as confined working spaces, harsh deep-sea environments, grasping soft objects, human-machine interaction, and wearable devices. Bionic robotic fish, as underwater soft robots, combine the swimming mechanics of bionic fish with robotic technology. They are gradually replacing traditional propeller-propelled underwater vehicles in areas such as marine resource exploration, seafloor topography mapping, and military missions.

[0003] Based on their propulsion system, fish in nature are categorized as either body and / or caudal fin (BCF) or median and / or paired fin (MPF). While MPF robotic fish prioritize maneuverability, BCF robotic fish prioritize speed and endurance, relying primarily on the body and caudal fin to propel them forward. Currently, the caudal fins of most BCF robotic fish are either single-rod or multi-link structures driven by a motor, while their pectoral fins are often fixed. This makes the robotic fish rigid and consumes a lot of power, making them less adaptable to complex and changing underwater environments.

[0004] The snorkeling movement of bionic robotic fish is mostly achieved by using the water storage tank method, pectoral fin method, center of gravity change method and shape change method. Among them, the snorkeling movement achieved by the water storage tank method is slow, the snorkeling movement achieved by the pectoral fin method is not obvious, the center of gravity change method will cause the weight of the entire robotic fish to increase and energy consumption to increase, and the shape change method is currently mostly achieved by traditional mechanical mechanisms.

[0005] The invention patent with application number 202211112075.X and application name is "A multi-drive high-strength flexible bionic robot fish". It mentions a bionic robot fish that uses a flexible pull rope and a tail joint to achieve tail fin swinging. Compared with the rigid connecting rod tail fin, the driving performance is improved, but its flexibility still needs to be improved. At the same time, it uses a servo to drive the pectoral fin to achieve steering, which increases flexibility, but the overall weight of the robot fish increases and energy consumption increases.

[0006] The utility model patent with application number 202222653683.3 and application name is "An electronic swim bladder device for a robotic fish". The bionic robotic fish mentioned uses a variable-volume airtight cavity composed of a gear set, a worm gear, a motor, a drive shaft and a rigid plate as a swim bladder snorkeling mechanism. Compared with the center of gravity adjustment mechanism, it reduces the overall weight of the robotic fish, but due to the use of more rigid mechanical mechanisms, its flexibility is insufficient.

[0007] With the development of intelligent soft materials and bionic technologies, it has become a trend to introduce intelligent soft materials into the driving mechanism of bionic robotic fish, use their passive deformation performance of "small stimulation, large response" to simulate the swimming of natural fish, and imitate the swim bladder mechanism to realize the snorkeling of robotic fish. Summary of the Invention

[0008] In response to the shortcomings of the existing technology, the present invention provides a rigid-flexible coupling bionic robotic fish that imitates fish bladder snorkeling. It adopts SMA flexible tail fin, electromagnetically driven pectoral fins and a fish bladder snorkeling mechanism, thereby narrowing the performance gap between robotic fish and biological systems and demonstrating relatively excellent motion performance.

[0009] The present invention achieves the above-mentioned purpose through the following technical solutions.

[0010] A rigid-flexible coupling bionic robotic fish capable of snorkeling by imitating a fish's swim bladder comprises an SMA flexible tail fin, an electromagnetically driven pectoral fin, a fish's swim bladder-mimicking mechanism, an outer shell covering, a MOS transistor, and a power supply. The SMA flexible tail fin is used to achieve variable stiffness of the bionic robotic fish's tail fin; the electromagnetically driven pectoral fin is used to enable the bionic robotic fish to move straight and / or turn; the fish's swim bladder-mimicking mechanism is used to enable the bionic robotic fish to snorkel; the outer shell covering is used to achieve water-tightness for the entire robotic fish; the MOS transistor is used as an electronic switch to control the on / off of each branch circuit; and the power supply is used to supply energy to the bionic robotic fish.

[0011] In the above scheme, the SMA flexible tail fin includes SMA wire, elastomer, passive tail fin, outer shell skin, water cooling device, tail air chamber, MOS transistor and power supply. The SMA wire connected to the wire is placed on the outside of the elastomer and is arranged in an offset manner. The SMA wire is in contact with the outer shell skin; the tail air chamber is installed between the two elastomers and is connected to the air chamber in the fish body by an air pump and an electromagnetic valve; after the passive tail fin is assembled on the SMA flexible module, it is the tail end of the bionic robotic fish.

[0012] In the above scheme, the SMA wire is folded into an "M" shape after pre-stretching, its closed end is cast with polydimethylsiloxane and glued to the elastomer, and the open end is connected to two wires. The "M"-shaped SMA wires are symmetrically arranged on both sides of the two elastomers.

[0013] In the above solution, the water cooling device is an "S"-shaped water pipe; the installation process of the water cooling device is: sticking the "S"-shaped water pipe water cooling device on the SMA wire, and then covering the water cooling device with an outer shell skin.

[0014] In the above scheme, a tail air chamber is installed between the two elastomers in the SMA wire flexible tail fin. The air chamber is connected to the air chamber inside the fish body. The gas flow between the air chamber inside the fish body and the tail air chamber is regulated by an air pump and a solenoid valve, thereby controlling the air pressure in the tail air chamber and achieving the flexibility of the flexible tail fin adjusted together with the SMA wire.

[0015] In the above scheme, the electromagnetically driven pectoral fins are installed symmetrically on the left and right, including electromagnets, pectoral fins, rigid frames, coils, rotating shafts, MOS transistors and power supplies; the rigid frame is a V-shaped structure symmetrical with the pectoral fins as the central axis, connected to the pectoral fins through a rotating shaft, and the coils are installed on the pectoral fins; the two electromagnets are connected to the wires and are respectively installed on the inner sides of the V-shaped rigid frame, and the movement of the pectoral fins is controlled by turning the power on or off the electromagnets.

[0016] In the above scheme, the rigid frame includes a first rigid frame and a second rigid frame; the electromagnet includes a first electromagnet, a second electromagnet, a third electromagnet and a fourth electromagnet; the pectoral fin includes a left pectoral fin and a right pectoral fin; the coil includes a first coil and a second coil; the left pectoral fin is provided with a first rigid frame through a rotating shaft; the right pectoral fin is provided with a second rigid frame through a rotating shaft, and the axis of the rotating shaft is parallel to the forward direction of the bionic robotic fish, thereby realizing the up and down swinging of the pectoral fin; the first electromagnet and the second electromagnet are symmetrically installed on the first rigid frame, and the third electromagnet and the fourth electromagnet are symmetrically installed on the second rigid frame, and the distance between the axis of the rotating shaft and the axis of the coil and the distance between the rotating sub-axis and the axis of the electromagnet are ensured to be equal, so that the coil on the pectoral fin can just contact the electromagnet when the pectoral fin swings up and down.

[0017] In the above scheme, a left turn can be achieved by energizing the first electromagnet and the fourth electromagnet; a right turn can be achieved by energizing the second electromagnet and the third electromagnet; and straight travel can be achieved by energizing the first electromagnet, the second electromagnet, the third electromagnet and the fourth electromagnet.

[0018] In the above scheme, the fish bladder imitation mechanism includes an air pump, a cylinder, a push rod and a push plate, a solenoid valve, an air circuit, an air storage chamber, a MOS transistor and a power supply; the air storage chamber is connected to the air pump, and there are two air pumps, which are arranged symmetrically in the upper and lower parts, wherein the upper air pump is connected to the cylinder through an air circuit, and one end of the push rod and the push plate is equipped in the cylinder, and the other end of the push rod and the push plate is in direct contact with the outer skin of the shell; the air pump can allow gas to enter or flow out of the cylinder through two air circuits, and two solenoid valves are provided on both air circuits, and the two solenoid valves are placed on both sides of the cylinder; the upper and lower ends of the cylinder are provided with inlets and outlets, and the inlets and outlets are both connected to the air circuit.

[0019] In the above scheme, the snorkeling of the bionic robotic fish is achieved by controlling the on and off of the solenoid valve to realize the movement of the push rod and push plate in the cylinder, thereby driving the expansion and contraction of the outer shell skin.

[0020] In the above scheme, the solenoid valves include a first solenoid valve b, a second solenoid valve c, a third solenoid valve f and a fourth solenoid valve g, and the push rod and the push plate divide the cylinder into a cylinder front chamber e and a cylinder rear chamber i.

[0021] In the above solution, the swim bladder-mimicking mechanism can realize the snorkeling movement of the robotic fish, namely the floating mode and the diving mode:

[0022] (1) Floating mode: The air pump sucks gas out of the air storage chamber, connects the second solenoid valve c and the third solenoid valve f to the circuit, turns on the second solenoid valve c and the third solenoid valve f, and turns off the first solenoid valve b and the fourth solenoid valve g. The gas enters the air chamber i after entering the cylinder, pushing the push rod and the push plate to move outward, thereby pushing the outer skin of the shell to expand. At this time, the volume of the bionic robot fish increases, and the buoyancy increases. After it is greater than the gravity of the bionic robot fish, it can float up;

[0023] (2) Diving mode: The first solenoid valve b and the fourth solenoid valve g are connected to the circuit, the first solenoid valve b and the fourth solenoid valve g are turned on, the second solenoid valve c and the third solenoid valve f are turned off, and the gas flows from the gas storage chamber through the first solenoid valve b into the front chamber e of the cylinder, driving the push rod and the push plate to move inward, and the gas in the rear chamber i of the cylinder is pressed back into the gas storage chamber through the fourth solenoid valve g, so that the outer skin of the shell shrinks inward. At this time, the volume of the bionic robot fish decreases, the buoyancy decreases, and it can dive after it is less than gravity.

[0024] Beneficial effects:

[0025] (1) The present invention adopts electromagnetically driven pectoral fins, which are controlled by turning on and off the electromagnet circuit to control the up and down swing of the pectoral fins to assist the bionic robot fish in turning and snorkeling, thereby enhancing its maneuverability to a certain extent while also reducing the complexity of its structure.

[0026] (2) The present invention uses shape memory alloy SMA wire among smart soft materials to form its tail fin, which greatly increases its flexibility. In addition, the SMA wire is offset on the elastomer, thereby providing a larger bending moment for the elastomer. Given that the thickness of the elastomer and the skin are relatively small, the maximum bending angle of the flexible tail fin is increased.

[0027] (3) The present invention adopts a water cooling device, and a very thin skin is separated from the SMA wire, so the water cooling effect is better. In addition, the water pipe of the water cooling device is designed in an "S" shape, so that the external water stays at the SMA wire of its flexible tail fin for a longer time during the movement of the bionic robot fish, causing the external water to take away more heat from the SMA wire, which to a certain extent reduces the defects of slow cooling and slow response of the SMA.

[0028] (4) The present invention adopts a tail air chamber to enhance the flexibility of its tail, and the tail air chamber is connected to the air chamber in the fish body, so that the gas content in the tail air chamber can be adjusted in real time during the underwater movement to control the change of the air pressure in the tail air chamber, and together with the SMA wire, realize the variable stiffness of the flexible tail fin.

[0029] (5) The present invention uses a pneumatic mechanism that mimics a fish bladder, and controls an electromagnetic on-off valve to achieve the snorkeling motion of the robotic fish. Compared with the center of gravity adjustment method, this method reduces the total weight of the robotic fish and lowers energy consumption. Compared with traditional mechanical mechanisms that mimic fish bladders to achieve snorkeling, this method has a faster response speed, less friction, and less energy consumption.

[0030] (6) The present invention can effectively achieve variable stiffness and flexible swinging of the tail fin, effectively solving the problem of slow cooling of SMA wire. The electromagnetically driven pectoral fins improve the maneuverability of the BCF robotic fish while also reducing the complexity of the mechanism. The swim bladder-like snorkeling mechanism has the advantages of being smaller and lighter than the center of gravity adjustment mechanism. In summary, the bionic robotic fish has good movement performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A side view of a rigid-flexible coupled bionic robotic fish that mimics fish snorkeling with a swim bladder according to an embodiment of the present invention;

[0032] Figure 2 for Figure 1 Schematic diagram of the left side;

[0033] Figure 3 for Figure 1 Schematic diagram of the right side;

[0034] Figure 4 Schematic diagram of the fish bladder-imitation mechanism.

[0035] The reference numerals are as follows:

[0036] 1-air pump; 2-cylinder; 3-push rod and push plate; 4-solenoid valve; 5-air path; 6-outer skin of the shell; 7-air chamber in the fish body; 8-SMA wire; 9-elastomer; 10-passive tail fin; 11-water cooling device; 12-flexible tail fin; 13-tail air chamber; 14-air chamber of the swim bladder mechanism; 15-electromagnet; 15a-first electromagnet; 15b-second electromagnet; 15c-third electromagnet; 15d-fourth electromagnet; 16-pectoral fin; 17-rigid frame; 17a-first rigid frame; 17b-second rigid frame; 18-coil; 18a-first coil; 18b-second coil; 19-rotating shaft; first solenoid valve b; second solenoid valve c; third solenoid valve f; fourth solenoid valve g; e front air chamber of cylinder; i rear air chamber of cylinder. DETAILED DESCRIPTION

[0037] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0038] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "axial", "radial", "vertical", "horizontal", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0039] In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "connect," "fixed," etc. should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0040] A rigid-flexible coupling bionic robotic fish capable of snorkeling by imitating a fish's swim bladder comprises an SMA flexible tail fin, an electromagnetically driven pectoral fin, a fish's swim bladder-mimicking mechanism, an outer shell covering, a MOS transistor, and a power supply. The SMA flexible tail fin is used to achieve variable stiffness of the bionic robotic fish's tail fin; the electromagnetically driven pectoral fin is used to enable the bionic robotic fish to move straight and turn; the fish's swim bladder-mimicking mechanism is used to enable the bionic robotic fish to snorkel; the outer shell covering is used to achieve water-tightness for the entire robotic fish; the MOS transistor is used as an electronic switch to control the on / off of each branch circuit; and the power supply is used to supply energy to the bionic robotic fish.

[0041] In the above scheme, the SMA flexible tail fin includes an SMA wire 8, an elastomer 9, a passive tail fin 10, an outer shell covering skin 6, a water cooling device 11, a tail air chamber 13, a MOS transistor 20 and a power supply 21. The SMA wire 8 connected to the wire is placed on the outside of the elastomer 9, and an offset arrangement is adopted. The water cooling device 11 is covered on the surface of the SMA wire 8 and then the outer shell covering skin 6 is applied. The tail air chamber 13 is installed between the two elastomers 9 and is connected to the air chamber 7 in the fish body by an air pump and an electromagnetic valve; after the passive tail fin 10 is assembled on the SMA flexible module, it is the tail end of the bionic robotic fish.

[0042] In the above scheme, the SMA wire 8 is folded into an "M" shape after pre-stretching. The closed end of the SMA wire 8 is cast and glued to the elastomer 9 by polydimethylsiloxane, and the open end is connected to two wires. The "M"-shaped SMA wire 8 is symmetrically arranged on both sides of the two elastomers 9.

[0043] In the above scheme, the water cooling device 11 is an "S"-shaped water pipe; the installation process of the water cooling device 11 is: sticking the "S"-shaped water pipe water cooling device 11 on the SMA wire 8, and then covering the outer shell skin 6 on the water cooling device 11.

[0044] In the above scheme, a tail air chamber is installed between the two elastomers in the SMA wire flexible tail fin. The air chamber is connected to the air chamber inside the fish body. The gas flow between the air chamber inside the fish body and the tail air chamber is regulated by an air pump and a solenoid valve, thereby controlling the air pressure in the tail air chamber and achieving the flexibility of the flexible tail fin adjusted together with the SMA wire.

[0045] In the above scheme, the SMA wire used in the flexible tail fin is selected to have a smaller diameter to maximize deformation during heating and cooling, thus increasing the fin's flexibility. The SMA wire is pre-stretched to allow for a certain degree of plastic deformation. It is folded into an "M" shape to cover a larger area of ​​the tail fin and better control its reciprocating motion. The closed end of the SMA wire is cast and bonded to the elastomer using polydimethylsiloxane to prevent relative displacement of the wire on the tail fin. The open end is connected to two wires for accessing an electrical circuit, which controls the wire's deformation by switching the circuit on and off. The "M"-shaped SMA wires are symmetrically arranged on either side of the elastomer. Furthermore, the SMA wires are offset from the elastomer to provide a larger bending moment. Given the relatively small thickness of the elastomer and the skin, this increases the maximum bending angle of the flexible tail fin. A passive tail fin installed at the rear end of the flexible tail fin unit can increase the effective propulsion of the flexible tail fin to a certain extent.

[0046] In the above scheme, given that the SMA wire heats up much faster than it cools down, resulting in a slow cooling and sluggish response, an S-shaped water cooling device with direct water pipes in contact with the SMA wire is designed to achieve a better cooling effect. The S-shaped water pipes in this water cooling device prolong the time that water remains near the SMA wire in the bionic robotic fish's flexible tail fin during movement, increasing the amount of heat removed from the wire and mitigating the inherent drawbacks of the SMA wire. Because the water cooling device weighs more than the SMA wire, a skin is used to secure it.

[0047] In the above scheme, the electromagnetically driven pectoral fins are installed symmetrically on the left and right, including an electromagnet 15, a pectoral fin 16, a rigid frame 17, a coil 18, a rotating shaft 19, a MOS transistor 20 and a power supply 21; the rigid frame 17 is a V-shaped structure symmetrical with the pectoral fin 16 as the central axis, connected to the pectoral fin 16 through the rotating shaft 19, and the coil 18 is installed on the pectoral fin 16; the two electromagnets 15 are connected to the wires and are respectively installed on the inner sides of the V-shaped rigid frame 17, and the movement of the pectoral fin 16 is controlled by turning on or off the power to the electromagnet 15.

[0048] In the above scheme, the rigid frame includes a first rigid frame 17a and a second rigid frame 17b; the electromagnet 15 includes a first electromagnet 15a, a second electromagnet 15b, a third electromagnet 15c and a fourth electromagnet 15d; the pectoral fin 16 includes a left pectoral fin 16a and a right pectoral fin 16b; the coil 18 includes a first coil 18a and a second coil 18b; the left pectoral fin 16a is provided with a first rigid frame 17a via a rotating shaft 19; the right pectoral fin 16b is provided with a second rigid frame 17b via a rotating shaft 19 The axis of the rotating shaft 19 is parallel to the forward direction of the bionic robotic fish, thereby realizing the up and down swinging of the pectoral fin 16; the first electromagnet 15a and the second electromagnet 15b are symmetrically installed on the first rigid frame 17a, and the third electromagnet 15c and the fourth electromagnet 15d are symmetrically installed on the second rigid frame 17b, and the distance between the axis of the rotating shaft 19 and the axis of the coil 18 is equal to the distance between the axis of the rotating pair 19 and the axis of the electromagnet 15, so that the coil 18 on it can just contact the electromagnet 15 when the pectoral fin swings up and down.

[0049] In the above scheme, a left turn can be achieved by energizing the first electromagnet 15a and the fourth electromagnet 15d; a right turn can be achieved by energizing the second electromagnet 15b and the third electromagnet 15c; and straight travel can be achieved by energizing the first electromagnet 15a, the second electromagnet 15b, the third electromagnet 15c and the fourth electromagnet 15d.

[0050] In the above scheme, the fish bladder imitation mechanism includes an air pump 1, a cylinder 2, a push rod and a push plate 3, an electromagnetic valve 4, an air circuit 5, an air storage chamber 14, a MOS transistor 20 and a power supply 21; the air storage chamber 14 is connected to the air pump 1, and there are two air pumps 1, which are symmetrically arranged in an upper and lower manner, wherein the upper air pump 1 is connected to the cylinder 2 through the air circuit 5, and one end of the push rod and the push plate 3 is equipped in the cylinder 2, and the other end of the push rod and the push plate 3 is in direct contact with the outer covering skin 6 of the shell; the air pump 1 can make the gas in the air storage chamber 14 enter or flow out of the cylinder 2 through two air circuits 5, and two electromagnetic valves 4 are provided on the two air circuits 5, and the two electromagnetic valves 4 are placed on both sides of the cylinder 2; the upper and lower ends of the cylinder 2 are provided with an inlet and an outlet, and the inlet and outlet are both connected to the air circuit 5.

[0051] In the above scheme, the snorkeling of the bionic robotic fish is achieved by controlling the on-off of the electromagnetic valve 4 to realize the movement of the push rod and the push plate 3 in the cylinder 2, thereby driving the outer covering skin 6 of the shell to expand and contract.

[0052] In the above scheme, the solenoid valve 4 includes a first solenoid valve b, a second solenoid valve c, a third solenoid valve f and a fourth solenoid valve g, and the push rod and the push plate 3 divide the cylinder 2 into a cylinder front chamber e and a cylinder rear chamber i.

[0053] In the above solution, the swim bladder-mimicking mechanism can realize the snorkeling movement of the robotic fish, namely the floating mode and the diving mode:

[0054] (1) Floating mode: The air pump 1 sucks gas out of the air storage chamber 14, connects the second solenoid valve c and the third solenoid valve f to the circuit, turns on the second solenoid valve c and the third solenoid valve f, and turns off the first solenoid valve b and the fourth solenoid valve g. The gas enters the air chamber i after entering the cylinder, pushing the push rod and the push plate 3 to move outward, thereby pushing the outer skin 6 of the shell to expand. At this time, the volume of the bionic robot fish increases, and the buoyancy increases. After it is greater than the gravity of the bionic robot fish, it can float up;

[0055] (2) Diving mode: The first solenoid valve b and the fourth solenoid valve g are connected to the circuit, the first solenoid valve b and the fourth solenoid valve g are turned on, and the second solenoid valve c and the third solenoid valve f are turned off. The gas flows from the gas storage chamber 14 through the first solenoid valve b into the front air chamber e of the cylinder, driving the push rod and the push plate 3 to move inward. The gas in the rear air chamber i of the cylinder is pressed back into the gas storage chamber 14 through the fourth solenoid valve g, so that the outer covering skin 6 of the shell shrinks inward. At this time, the volume of the bionic robot fish decreases, the buoyancy decreases, and it can dive after it is less than the gravity.

[0056] Example:

[0057] Combined with attachment Figure 1-4 A rigid-flexible coupling bionic robotic fish that imitates the swim bladder snorkeling, including an air pump 1, an air cylinder 2, a push rod and a push plate 3, an electromagnetic valve 4, an air path 5, an outer skin of the shell 6, an air chamber 7 in the fish body, an SMA wire 8, an elastic body 9, a passive tail fin 10, a water cooling device 11, an SMA wire flexible tail fin 12, a tail air chamber 13, an air chamber of the swim bladder mechanism 14, an electromagnet 15, an electromagnetically driven pectoral fin 16, a rigid frame 17, a coil 18, a rotating shaft 19, a MOS transistor 20 and a power supply 21. The component modules include S MA flexible tail fin, electromagnetically driven pectoral fin, imitation fish bladder mechanism, outer shell covering skin, MOS transistor and power supply; the SMA flexible tail fin is used to achieve variable stiffness of the tail fin of the bionic robotic fish; the electromagnetically driven pectoral fin is used to enable the bionic robotic fish to move straight and turn; the imitation fish bladder mechanism is used to enable the bionic robotic fish to snorkel; the outer shell covering skin is used to achieve water tightness of the entire robotic fish; the MOS transistor is used as an electronic switch to control the on and off of each branch circuit; the power supply is used to supply energy to the bionic robotic fish.

[0058] The SMA flexible tail fin includes an SMA wire 8, an elastomer 9, a passive tail fin 10, a water cooling device 11, a tail air chamber 13, an outer shell covering skin 6, a MOS transistor 20 and a power supply 21. An SMA wire 8 connected to a wire is placed on the outside of the elastomer 9, and an offset arrangement is adopted. The water cooling device 11 is covered on the surface of the SMA wire 8 and then the outer shell covering skin 6 is adopted. The tail air chamber 13 is installed between two elastomers 9 and is connected to the air chamber 7 in the fish body by an air pump and an electromagnetic valve; after the passive tail fin 10 is assembled on the SMA flexible module, it is the tail end of the bionic robotic fish.

[0059] The SMA wire 8 of the flexible tail fin is designed with a diameter of 0.2 mm to maximize deformation during heating and cooling, thus enhancing the fin's flexibility. The SMA wire 8 is pre-stretched to allow for a certain degree of plastic deformation. It is folded into an "M" shape to cover a larger area of ​​the tail fin and better control its reciprocating motion. The closed end of the SMA wire 8 is cast and bonded to the elastomer 9 using polydimethylsiloxane to prevent relative displacement of the wire. The open end is connected to two wires for accessing an electrical circuit, which controls the deformation of the wire 8 by switching the circuit on and off. The "M"-shaped SMA wires 8 are symmetrically arranged on either side of the elastomer 9. Furthermore, the SMA wires 8 are offset from the elastomer 9, imparting a greater bending moment to the elastomer. Given the relatively small thickness of the elastomer 9 and the outer skin 6, this increases the maximum bending angle of the flexible tail fin. A passive tail fin 10, installed at the rear end of the flexible tail fin unit, contributes to the effective propulsion of the flexible tail fin.

[0060] Given that the SMA wire 8 heats up much faster than it cools down, meaning it cools down slowly and responds slowly, an S-shaped water pipe cooling device 11 is designed to directly contact the SMA wire 8, resulting in a better water cooling effect. The S-shaped water pipe design of the water cooling device 11 prolongs the time that external water spends at the SMA wire 8 on the flexible tail fin 12 of the bionic robotic fish during its movement, increasing the amount of heat carried away by the external water from the SMA wire 8 and, to a certain extent, mitigating the drawbacks of the SMA wire's slow cooling and response. Because the water cooling device 11 weighs more than the SMA wire 8, a 0.5mm thick outer shell covering 6 is used to secure it. The water cooling device installation process involves attaching the S-shaped water pipe cooling device to the SMA wire and then covering the outer shell covering the water cooling device.

[0061] A tail air chamber 13 is installed between the two elastomers 9 in the flexible tail fin. The air chamber is connected to the air chamber 7 in the fish body. The gas flow between the air chamber 7 in the fish body and the tail air chamber 13 is regulated by an air pump and a solenoid valve, thereby controlling the air pressure in the tail air chamber 13 and achieving the flexibility of the flexible tail fin adjusted together with the SMA wire 8.

[0062] The electromagnetically driven pectoral fin is installed symmetrically on the left and right, including an electromagnet 15, a pectoral fin 16, a rigid frame 17, a coil 18, a rotating shaft 19, a MOS transistor 20 and a power supply 21; the rigid frame 17 is connected to the pectoral fin 16 through the rotating shaft 19, and the rigid frame 17 is a V-shaped structure. The rigid frame 17 is symmetrical with the pectoral fin 16 as the center axis, and the coil 18 is installed on the pectoral fin 16; the two electromagnets 15 are connected to the wires and are respectively installed on the inner sides of the V-shaped rigid frame 17, and the movement of the pectoral fin 16 is controlled by turning on or off the power to the electromagnet 15.

[0063] The rigid frame includes a first rigid frame 17a and a second rigid frame 17b; the electromagnet 15 includes a first electromagnet 15a, a second electromagnet 15b, a third electromagnet 15c and a fourth electromagnet 15d; the pectoral fin 16 includes a left pectoral fin 16a and a right pectoral fin 16b; the coil 18 includes a first coil 18a and a second coil 18b; the left pectoral fin 16a is provided with a first rigid frame 17a via a rotating shaft 19; the right pectoral fin 16b is provided with a second rigid frame 17b via a rotating shaft 19, and the rotating shaft The axis 19 is parallel to the forward direction of the bionic robotic fish, thereby realizing the up and down swinging of the pectoral fin 16; the first electromagnet 15a and the second electromagnet 15b are symmetrically mounted on the first rigid frame 17a, and the third electromagnet 15c and the fourth electromagnet 15d are symmetrically mounted on the second rigid frame 17b, and the distance between the axis of the rotating shaft 19 and the axis of the coil 18 is equal to the distance between the axis of the rotating pair 19 and the axis of the electromagnet 15, so that the coil 18 on it can just contact the electromagnet 15 when the pectoral fin swings up and down.

[0064] A left turn can be achieved by energizing the first electromagnet 15a and the fourth electromagnet 15d; a right turn can be achieved by energizing the second electromagnet 15b and the third electromagnet 15c; and straight travel can be achieved by energizing the first electromagnet 15a, the second electromagnet 15b, the third electromagnet 15c and the fourth electromagnet 15d.

[0065] The fish bladder imitation mechanism includes an air pump 1, a cylinder 2, a push rod and a push plate 3, an electromagnetic valve 4, an air circuit 5, an air storage chamber 14, a MOS transistor 20 and a power supply 21; the air storage chamber 14 is connected to the air pump 1, and there are two air pumps 1, which are symmetrically arranged in an upper and lower manner, wherein the upper air pump 1 is connected to the cylinder 2 through the air circuit 5, and one end of the push rod and the push plate 3 is equipped in the cylinder 2, and the other end of the push rod and the push plate 3 is in direct contact with the outer covering skin 6 of the shell; the air pump 1 can make the gas in the air storage chamber 14 enter or flow out of the cylinder 2 through two air circuits 5, and two electromagnetic valves 4 are provided on the two air circuits 5, and the two electromagnetic valves 4 are placed on both sides of the cylinder 2; the upper and lower ends of the cylinder 2 are provided with an inlet and an outlet, and the inlet and outlet are both connected to the air circuit 5.

[0066] The snorkeling of the bionic robotic fish is achieved by controlling the on-off state of the electromagnetic valve 4 to realize the movement of the push rod and the push plate 3 in the cylinder 2, thereby driving the outer covering skin 6 of the shell to expand and contract.

[0067] The solenoid valve 4 includes a first solenoid valve b, a second solenoid valve c, a third solenoid valve f and a fourth solenoid valve g. The push rod and the push plate 3 divide the cylinder 2 into a cylinder front chamber e and a cylinder rear chamber i.

[0068] The driving principle of the SMA flexible tail fin is as follows: SMA wire 8 on one side of the SMA flexible tail fin is electrically heated. When the temperature rises to the SMA wire's phase transition temperature, the SMA wire 8 transforms from low-temperature martensite to high-temperature austenite, causing the flexible tail fin 12 to deform and contract, generating a restoring force. After the temperature reaches the end temperature of the austenite phase transition, the power is turned off and the device is cooled. During this process, the SMA wire 8 transforms back to low-temperature martensite, reducing the recovery stress and releasing the elastic energy, thereby causing the flexible tail fin 12 to expand to its original shape. By alternating the circuits of the SMA wires 8 on both sides, bidirectional bending of the flexible tail fin 12 can be achieved.

[0069] The driving principle of the electromagnetic driven pectoral fins is to control the swing of the pectoral fins 16 by controlling the on and off of the electromagnet 15 circuit to assist the bionic robot fish in turning and snorkeling, thereby enhancing its maneuverability. Figure 3 As shown, when the second electromagnet 15b below the first rigid frame 17a on the left side of the bionic robotic fish and the third electromagnet 15c above the second rigid frame 17b on the right side are energized at the same time, the first coil 18a on the left pectoral fin 16a is subjected to a downward magnetic force, and the left pectoral fin 16a swings downward around the axis of the first rotation axis 19a, and the second coil 18b on the right pectoral fin 16b is subjected to an upward magnetic force, and the right pectoral fin 16b swings upward around the axis of the second rotation axis 19b. At this time, the robotic fish as a whole will be subjected to a leftward deflection component force, which cooperates with the swing of the tail fin 12 to assist in achieving a left turn. Similarly, when the first electromagnet 15a above the first rigid frame 17a on the left side of the bionic robotic fish and the fourth electromagnet 15d below the second rigid frame 17b on the right side are energized at the same time, the left pectoral fin 16a swings upward, and the right pectoral fin 16b swings downward, cooperating with the tail fin 12 to assist in turning right. When the first electromagnet 15a and the third electromagnet 15c above the first rigid frame 17a and the second rigid frame 17b on both sides are energized at the same time, the left pectoral fin 16a and the right pectoral fin 16b on both sides swing upward, cooperating with the swim bladder mechanism to assist in floating movement. When the second electromagnet 15b and the fourth electromagnet 15d below the first rigid frame 17a and the second rigid frame 17b on both sides are energized at the same time, the left pectoral fin 16a and the right pectoral fin 16b on both sides swing downward, cooperating with the swim bladder mechanism to assist in diving movement. The electromagnetically driven pectoral fin 16 not only improves the maneuverability and flexibility of the bionic robotic fish but also reduces the complexity of the pectoral fin mechanism.

[0070] The swim bladder mechanism can realize the snorkeling movement of the robot fish, that is, the floating mode and the diving mode. The specific driving principle is: the piston 3 of the cylinder 2 is moved by the on-off of the air pump 1 and the electromagnetic valve 4, thereby driving the outer skin 6 of the shell to expand and contract, changing the volume of the robot fish, thereby changing the buoyancy of the robot fish and realizing the snorkeling movement of the bionic robot fish. Figure 4 As shown, the air pump a draws gas from the air storage chamber h, connects the second solenoid valve c and the third solenoid valve f to the circuit, turns on the second solenoid valve c and the third solenoid valve f, and turns off the first solenoid valve b and the fourth solenoid valve g. Gas enters the rear air chamber i of the cylinder, pushing the piston outward, thereby driving the push rod and the push plate d to move outward, pushing the outer skin 6 to expand. At this time, the volume of the bionic robotic fish increases, and the buoyancy increases. After the buoyancy exceeds the weight of the robotic fish, it floats up. The first solenoid valve b and the fourth solenoid valve g are connected to the circuit, turns on the first solenoid valve b and the fourth solenoid valve g, and turns off the second solenoid valve c and the third solenoid valve f. Gas flows from the air storage chamber h through the first solenoid valve b into the front air chamber e of the cylinder, driving the piston to move inward. The gas in the rear air chamber i of the cylinder is pressed back into the air storage chamber h through the fourth solenoid valve g. At this time, the inward movement of the piston drives the push rod inward, causing the outer skin 6 to contract inward. The volume of the bionic robotic fish decreases, and the buoyancy decreases. After the buoyancy is less than the weight, it dives.

[0071] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that a specific feature, structure, material, or characteristic described in conjunction with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0072] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

[0073] The contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A rigid-flexible coupled bionic robotic fish that mimics fish snorkeling, characterized by: The invention comprises an SMA flexible tail fin, an electromagnetically driven pectoral fin, a fish bladder-like mechanism, an outer shell covering skin (6), a MOS transistor and a power supply; the SMA flexible tail fin is used to realize the tail fin stiffness change and drive of the bionic robot fish; the electromagnetically driven pectoral fin is used to realize the straight movement and / or turning of the bionic robot fish; the fish bladder-like mechanism is used to realize the snorkeling of the bionic robot fish; the outer shell covering skin (6) is used to realize the sealing of the entire robot fish; the MOS transistor is used as an electronic switch to control the on and off of each branch circuit; the power supply is used to supply energy to the bionic robot fish; the SMA flexible tail fin comprises an outer shell covering skin (6), an SMA wire (8), an elastic body (9), a passive tail fin (10), a water cooling device (11) and a tail air chamber (13); the outer side of the elastic body (9) is offset with an SMA wire (8); the water cooling device (11) and the SMA wire (8) are connected to each other. The rear shell is tightly fitted with a skin (6); the tail air chamber (13) is installed between two elastic bodies (9) and is connected to the air chamber (7) in the fish body by an air pump and an electromagnetic valve; the passive tail fin (10) is assembled on the SMA flexible module and is the tail end of the bionic robot fish; the electromagnetic driven pectoral fin is installed symmetrically on the left and right, including an electromagnet (15), a pectoral fin (16), a rigid frame (17), a coil (18) and a rotating shaft (19); the rigid frame (17) is connected to the pectoral fin (16) through the rotating shaft (19), the rigid frame (17) is a V-shaped structure, the rigid frame (17) is symmetrical with the pectoral fin (16) as the center axis, and the coil (18) is installed on the pectoral fin (16); the two electromagnets (15) are respectively arranged on the inner side of the V-shaped structure, and the movement of the pectoral fin (16) is controlled by turning on or off the power to the electromagnet (15).

2. The rigid-flexible coupled bionic robotic fish that imitates fish bladder snorkeling according to claim 1, characterized in that: The rigid frame includes a first rigid frame (17a) and a second rigid frame (17b); the electromagnet (15) includes a first electromagnet (15a), a second electromagnet (15b), a third electromagnet (15c) and a fourth electromagnet (15d); the pectoral fin (16) includes a left pectoral fin (16a) and a right pectoral fin (16b); the coil (18) includes a first coil (18a) and a second coil (18b); the left pectoral fin (16a) is provided with a first rigid frame (17a) via a rotating shaft (19); the right pectoral fin ( A second rigid frame (17b) is provided on the bionic robotic fish via a rotating shaft (19), and the axis of the rotating shaft (19) is parallel to the forward direction of the bionic robotic fish; the first electromagnet (15a) and the second electromagnet (15b) are symmetrically mounted on the first rigid frame (17a), and the third electromagnet (15c) and the fourth electromagnet (15d) are symmetrically mounted on the second rigid frame (17b), and the distance between the axis of the rotating shaft (19) and the axis of the coil (18) is equal to the distance between the axis of the rotating shaft (19) and the axis of the electromagnet (15).

3. The rigid-flexible coupled bionic robotic fish that imitates fish bladder snorkeling according to claim 1, characterized in that: By energizing the first electromagnet (15a) and the fourth electromagnet (15d), a left turn can be achieved; by energizing the second electromagnet (15b) and the third electromagnet (15c), a right turn can be achieved; and by energizing the first electromagnet (15a), the second electromagnet (15b), the third electromagnet (15c) and the fourth electromagnet (15d), straight travel can be achieved.

4. The rigid-flexible coupled bionic robotic fish that imitates fish bladder snorkeling according to claim 1, characterized in that: The fish bladder-imitation mechanism comprises an air pump (1), an air cylinder (2), a push rod and a push plate (3), an electromagnetic valve (4), an air path (5) and an air storage chamber (14); the air storage chamber (14) is connected to the air pump (1), and there are two air pumps (1) arranged symmetrically in an upper and lower manner, wherein the air pump (1) on the upper side is connected to the air cylinder (2) through the air path (5), one end of the push rod and the push plate (3) is matched in the air cylinder (2), and the other end of the push rod and the push plate (3) is in direct contact with the outer cover (6) of the shell; the air pump (1) can allow gas to enter or flow out of the air cylinder (2) through the two air paths (5), and two electromagnetic valves (4) are provided on both sides of the air cylinder (2); an inlet and an outlet are provided at the upper end and the lower end of the air cylinder (2), and the inlet and the outlet are both connected to the air path (5).

5. The rigid-flexible coupled bionic robotic fish that imitates fish bladder snorkeling according to claim 4, characterized in that: The snorkeling of the bionic robotic fish is achieved by controlling the on-off of the electromagnetic valve (4) to realize the movement of the push rod and the push plate (3) in the cylinder (2), thereby driving the expansion and contraction of the outer covering skin (6) of the shell.

6. The rigid-flexible coupled bionic robotic fish that imitates fish bladder snorkeling according to claim 4, characterized in that: The solenoid valve (4) includes a first solenoid valve b, a second solenoid valve c, a third solenoid valve f and a fourth solenoid valve g. The push rod and the push plate (3) divide the cylinder (2) into a cylinder front air chamber e and a cylinder rear air chamber i.

7. The rigid-flexible coupled bionic robotic fish that imitates fish bladder snorkeling according to claim 6, characterized in that: Including ascent mode and descent mode; Floating mode: the air pump (1) sucks gas out of the gas storage chamber (14), connects the second solenoid valve c and the third solenoid valve f to the circuit, the second solenoid valve c and the third solenoid valve f are turned on, the first solenoid valve b and the fourth solenoid valve g are turned off, and the gas enters the air chamber i after entering the cylinder, pushing the push rod and the push plate (3) to move outward, thereby pushing the outer skin (6) of the shell to expand. At this time, the volume of the bionic robot fish increases, the buoyancy increases, and the bionic robot fish floats after the volume is greater than the gravity of the bionic robot fish; Diving mode: the first solenoid valve b and the fourth solenoid valve g are connected to the circuit, the first solenoid valve b and the fourth solenoid valve g are turned on, the second solenoid valve c and the third solenoid valve f are turned off, and the gas flows from the gas storage chamber (14) through the first solenoid valve b into the front air chamber e of the cylinder, driving the push rod and the push plate (3) to move inward, and the gas in the rear air chamber i of the cylinder is pressed back into the gas storage chamber (14) through the fourth solenoid valve g, so that the outer covering skin (6) of the shell shrinks inward. At this time, the volume of the bionic robot fish decreases, the buoyancy decreases, and it can dive after being less than the gravity.

8. The rigid-flexible coupled bionic robotic fish that imitates fish bladder snorkeling according to claim 1, characterized in that: The SMA wire (8) is pre-stretched and folded into an "M" shape. The closed end of the SMA wire (8) is cast with polydimethylsiloxane and adhered to the elastomer (9). The open end is connected to two wires. The "M"-shaped SMA wires (8) are symmetrically arranged on both sides of the two elastomers (9).

9. The rigid-flexible coupled bionic robotic fish that imitates fish bladder snorkeling according to claim 1, characterized in that: The water cooling device (11) is an "S"-shaped water pipe; the installation process of the water cooling device (11) is as follows: the "S"-shaped water pipe water cooling device (11) is pasted on the SMA wire (8), and then the outer shell covering skin (6) is covered on the water cooling device (11).

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