Frog-like soft robot based on gas-liquid phase change

Abstract

This invention provides a frog-like soft robot based on gas-liquid phase change, belonging to the field of soft robot technology. It includes: a frog-like shell, legs, and a bistable gripper. The frog-like shell is connected to the legs via bionic joints. Rolled bionic webbed feet are installed on the outer side of the legs. The shell contains a control module, an electromagnetic heating device, and buoyancy foam. A bionic swim bladder is located on top of the shell. The bistable gripper is connected to the bottom of the frog-like shell. The bionic joints utilize the vaporization of a low-temperature phase change material to increase the pressure of a flexible sealed air bladder, overcoming the resistance of the elastic sheet and enabling the legs to extend and paddle. The rolled bionic webbed feet consist of an elastic rolled steel sheet and a sealed plastic film. Heating the low-temperature phase change material vaporizes and fills the sealed plastic film, causing the elastic rolled steel sheet to unfold. The bionic swim bladder utilizes a copper-based graphene sheet to absorb laser heat, causing the low-temperature phase change material to vaporize and fill the sealed plastic air bladder, achieving buoyancy. This soft robot is small in size, capable of long-term low-voltage, rapid response operation, and can undergo a wide range of deformation.

Description

Technical Field

[0001] This invention relates to the field of soft robot technology, and in particular to a frog-like soft robot based on gas-liquid phase change. Background Technology

[0002] The ocean and other aquatic environments are rich in resources and diverse in life, but due to the complexity of the environment and the sensitivity and vulnerability of organisms, traditional high-noise, large-volume rigid robots cannot meet the needs. Therefore, researchers have developed soft biomimetic swimming robots, whose excellent adaptability, safety, and camouflage effects better meet the needs of seabed exploration, reconnaissance in sensitive waters, biological monitoring, and capture.

[0003] Among amphibians, frogs not only possess excellent jumping abilities but can also swim rapidly in water. Frogs propel themselves by coordinating the extension of their legs and the backward paddling of their large webbed feet. This gives frogs better stability, maneuverability, and swimming efficiency than fish. Therefore, many researchers have conducted in-depth studies on frog-inspired swimming robots.

[0004] In the emerging field of robotics research, soft robots have become a key research focus due to their outstanding environmental adaptability and safe human-robot interaction. Existing frog-like soft robots mainly employ actuation methods such as shape memory alloys, dielectric elastomers, pneumatic muscles, and magnetic actuators. However, pneumatic and magnetic actuation require complex and bulky external equipment, making independent long-term operation impossible. Dielectric elastomers require high voltage to achieve small-range deformation and pose a risk of electrical leakage. Shape memory alloy actuators have slow response times and low efficiency.

[0005] In view of the above reasons, the present invention proposes a frog-like soft robot based on gas-liquid phase change to solve the above technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a frog-like soft robot based on gas-liquid phase change. This soft robot is small in size, can achieve long-term low-voltage rapid response operation, and can undergo a wide range of deformation.

[0007] This invention provides a frog-like soft robot based on gas-liquid phase change, comprising: a frog shell, legs, and a bistable gripper. The two sides of the frog shell are movably connected to the legs via bionic joints. The outer sides of the legs are fitted with rolled bionic webs. The frog shell contains a control module, an electromagnetic heating device, and buoyancy foam. The top of the frog shell has multiple bionic swim bladders. The bistable gripper is fixedly connected to the bottom of the frog shell.

[0008] The bionic joint includes an elastic sheet integrally connected to the leg. A flexible sealing airbag is attached to one side of the elastic sheet. The flexible sealing airbag contains a porous composite material with iron powder attached and filled with a low-temperature phase change material. The iron powder can generate eddy currents and release heat under the action of the high-frequency alternating magnetic field generated by the electromagnetic heating device. The low-temperature phase change material vaporizes, causing the air pressure of the flexible sealing airbag to increase, overcome the resistance of the elastic sheet, and unfold, so as to realize the extension and paddling of the leg.

[0009] The coiled bionic flippers include an elastic coiled steel sheet and a sealed plastic film bonded to it. The sealed plastic film is filled with a low-temperature phase change material and is provided with ceramic heating plates arranged at intervals. The ceramic heating plates can heat the low-temperature phase change material to vaporize and fill the sealed plastic film, so that it and the elastic coiled steel sheet can unfold together.

[0010] The biomimetic swim bladder includes multiple layers of sealed plastic airbags, forming multiple chambers. The top and bottom chambers are filled with low-temperature phase change material, and a copper-based graphene sheet is disposed in the middle of the low-temperature phase change material. The copper-based graphene sheet can absorb laser heat to vaporize the low-temperature phase change material and fill the sealed plastic airbags, thereby increasing its volume and enabling it to float.

[0011] Preferably, the low-temperature phase change material is hexafluorobutene.

[0012] Preferably, an adjusting block is provided inside the frog's outer shell, and an adjusting screw passes through the adjusting block and is threadedly connected to it. The two ends of the adjusting screw are fixedly connected to the inner wall of the frog's outer shell.

[0013] Preferably, the cavity porous composite material is further provided with nano-peroxygenated graphene material, and the iron powder and the nano-peroxygenated graphene material are uniformly attached to the cavity porous composite material, wherein the iron powder is in the millimeter scale.

[0014] Preferably, the head of the frog's body shell is equipped with an underwater camera, an ultrasonic detector, and a GPS locator.

[0015] Preferably, the leg is integrally connected to the elastic sheet, and both the leg and the elastic sheet are sheet structures made of PLA material by 3D printing.

[0016] Preferably, the biomimetic swim bladder comprises three sealed plastic air bladders, with a first chamber formed between the upper and middle layers, and a second chamber formed between the middle and lower layers. The copper-based graphene sheet is disposed in the middle of the first and second chambers. Both the first and second chambers are filled with low-temperature phase change material, and a temperature sensor is placed inside the low-temperature phase change material. The temperature sensor is electrically connected to the control module. Biomimetic swim bladders of different sizes are provided with borders of different colors.

[0017] Preferably, the system also includes a shore-based control system, which includes a PID controller, a servo gimbal, a laser emitter, a camera, and a PC. The camera can identify the border color of the biomimetic swim bladder and locate the position of the copper-based graphene sheet. The camera transmits the color and position information data to the PID controller in real time via the PC, thereby controlling the rotation of the servo gimbal so that the camera and the laser emitter are aligned with the biomimetic swim bladder. This heats the copper-based graphene sheet on the biomimetic swim bladder, generating the required buoyancy.

[0018] Preferably, the bistable gripper includes a bistable spring, a silicone tube, a miniature electromagnet, a corrugated flexible actuator, and a ceramic heating plate. The bistable spring comprises three sets, each fixedly connected to the bottom of the frog's outer shell via a rod. The corrugated flexible actuator is installed on the inner and outer sides of each set of bistable springs. The corrugated flexible actuator contains a low-temperature phase change liquid and the ceramic heating plate. The silicone tube is filled with a mixed liquid metal. Initially, the bistable spring is in a stable, outward-opening state. Heating the low-temperature phase change liquid within the outer corrugated flexible actuator by the ceramic heating plate increases the internal pressure, causing the bistable spring to deform inward and transform into an inward-facing stable state, thus closing the bistable gripper. The miniature electromagnet, when energized, generates a magnetic field that solidifies the mixed liquid metal within the silicone tube, thereby locking the bistable gripper.

[0019] Preferably, the mixed liquid metal is a gallium-iron alloy.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The frog-like soft robot is equipped with bionic joints, a bionic swim bladder, bionic flippers, and a bistable gripper. The bionic joints utilize a high-frequency alternating magnetic field generated by an electromagnetic heating device to induce eddy currents in iron powder and release heat. This causes a low-temperature phase change material to vaporize from a liquid state, increasing the pressure in a flexible, sealed airbag. This pressure overcomes the resistance of the elastic sheet, allowing the airbag to expand and extend, enabling the legs to extend and propel the robot. The bionic swim bladder controls swimming depth. Laser heating of the low-temperature phase change material increases the volume of the sealed plastic airbag, thereby increasing buoyancy and allowing the robot to float. After heating stops, the natural cooling effect of water allows for rapid sinking; the bionic flippers use ceramic heating elements to heat a low-temperature phase change material, causing it to vaporize and fill a sealing plastic film, which then unfolds together with an elastic rolled steel sheet. After heating stops, the elastic rolled steel sheet can be wound up and retracted through natural cooling of water, simulating the opening and closing process of frog flippers in nature, thus improving the overall efficiency of the frog-like soft robot's forward movement; the bistable gripper can switch between two steady states under the action of the low-temperature phase change material, enabling the gripper to close and open.

[0022] 2. This frog-like soft robot features miniaturization, low pressure, rapid response, and biocompatibility. It simplifies the connection process and helps reduce the size, cost, and weight of the actuator. It can generate large deformations in a short time from a low-voltage source without complex external equipment or any external cables or wires. It can work multiple times and has good biocompatibility.

[0023] 3. By directly triggering phase change using a low-voltage device, it is easy to control, low in cost, and can generate large motion or transformation within a limited time. Compared with other driving methods, it simplifies the connection steps, paving the way for the manufacture of fast-response modular robot systems, which are lighter and more compact. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the overall structure of the frog-inspired soft robot of the present invention;

[0026] Figure 2 This is a schematic diagram of the internal structure of the frog's outer shell in this invention;

[0027] Figure 3 This is a schematic diagram of the unfolded and rolled-up states of the bionic flipper in this invention;

[0028] Figure 4 This is a schematic diagram showing the planar connection of the bionic joint, leg, and coiled bionic webbed feet in this invention.

[0029] Figure 5 This is a planar schematic diagram of the biomimetic swim bladder in this invention;

[0030] Figure 6 This is a three-dimensional schematic diagram of the biomimetic swim bladder in this invention;

[0031] Figure 7 This is a top view of the bistable gripper in this invention;

[0032] Figure 8 This is a schematic diagram of the operation of the bistable gripper in this invention;

[0033] Figure 9 This is a control principle diagram of the biomimetic swim bladder and onshore control system in this invention;

[0034] Explanation of reference numerals in the attached figures:

[0035] 1: Leg; 2: Balance weight; 3: Adjusting screw; 4: Coil-shaped bionic fin; 5: Control module; 6: Ultrasonic detector; 7: Underwater camera; 8: Electromagnetic heating device; 9: Bionic joint; 10: Bionic swim bladder; 11: Buoyancy foam; 12: Bistable gripper; 13: Power module; 14: Ceramic heating element; 15: Plastic film airbag; 16: Elastic coiled steel sheet; 17: Wire; 18: Bionic fin in retracted state; 19: Hollow porous composite material; 20: First chamber; 21: Sealed plastic airbag; 22: Second chamber; 23: Copper-based graphene sheet; 24: Colored border; 25: Silicone hose; 26: Bistable spring; 27: Inner pleated flexible actuator; 28: Outer pleated flexible actuator. Detailed Implementation

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0039] like Figure 1-9 As shown, the present invention provides a frog-like soft robot based on gas-liquid phase change, comprising: a frog shell, legs 1 and a bistable gripper 12. The two sides of the frog shell are movably connected to the legs 1 through bionic joints 9. The outer side of the legs 1 is equipped with rolled bionic webs 4. The inside of the frog shell is provided with a control module 5, an electromagnetic heating device 8 and buoyancy foam 11. The top of the frog shell is provided with multiple bionic swim bladders 10. The bistable gripper 12 is fixedly connected to the bottom of the frog shell.

[0040] The bionic joint 9 includes an elastic sheet integrally connected to the leg 1. A flexible sealing airbag is attached to one side of the elastic sheet. The flexible sealing airbag contains a porous composite material with a cavity. Iron powder is attached to the porous composite material and filled with a low-temperature phase change material. The iron powder can generate eddy currents and release heat under the action of the high-frequency alternating magnetic field generated by the electromagnetic heating device 8. The low-temperature phase change material vaporizes, causing the air pressure of the flexible sealing airbag to increase, overcome the resistance of the elastic sheet, and unfold, so as to realize the extension and paddling of the leg 1.

[0041] The roll-shaped bionic flipper 4 includes an elastic roll-shaped steel sheet 16 and a sealing plastic film bonded to it. The sealing plastic film is filled with a low-temperature phase change material and is provided with ceramic heating plates 14 arranged at intervals. The ceramic heating plates 14 can heat the low-temperature phase change material to vaporize it and fill the sealing plastic film, so that it and the elastic roll-shaped steel sheet 16 can be unfolded together.

[0042] The biomimetic swim bladder 10 includes a multi-layer sealed plastic airbag 21, which forms multiple chambers. The top and bottom chambers are filled with low-temperature phase change material, and a copper-based graphene sheet 23 is disposed in the middle of the low-temperature phase change material. The copper-based graphene sheet 23 can absorb laser heat to vaporize the low-temperature phase change material and fill the sealed plastic airbag 21, thereby increasing its volume and enabling it to float.

[0043] The frog's outer shell is made of 3mm thick, 20-degree silicone. Silicone is more ecologically friendly, facilitating better biomimicry and making it more suitable for sensitive environments, exhibiting excellent biocompatibility. The upper outer layer is white to prevent damage from lasers. The upper and lower parts are connected with silicone adhesive; the upper part is used to fix and connect the biomimetic swim bladder 10 and the legs 1, while the lower part is equipped with buoyancy foam 11.

[0044] An adjusting block 2 is located inside the lower part of the frog-like outer shell. An adjusting screw 3 passes through the adjusting block 2 and is threadedly connected to it. Both ends of the adjusting screw 3 are fixedly connected to the inner wall of the lower layer of the frog-like outer shell. The position of the adjusting block 2 can be adjusted relative to the adjusting screw 3. By adjusting the position of the adjusting block 2, the center of gravity of the frog-like soft robot can be changed, allowing it to maintain a horizontal state in water. Buoyancy foam 11 is fixed inside the lower layer of the frog-like outer shell, providing it with basic buoyancy. When all the bionic swim bladders 10 are not in operation, this basic buoyancy allows the frog-like soft robot to be completely submerged in water and sink. At the same time, when the smallest bionic swim bladder 10 is activated, the frog-like soft robot can be in a suspended state in the water, that is, in a state where buoyancy and gravity exactly cancel each other out. This design ensures the stability and maneuverability of the frog robot in water and expands the range of motion of the frog-like soft robot in water.

[0045] The low-temperature phase change material selected is hexafluorobutene (i.e., Opteon SF33), which has the characteristics of high latent heat of vaporization, low boiling point, good safety, stable chemical properties, and good material compatibility. Its latent heat value at boiling point (33℃) is 164KJ / kg.

[0046] In this embodiment, the flexible sealing airbag measures 200mm × 30mm. The porous cavity composite material 19 also contains nano-peroxide graphene material. Iron powder and nano-peroxide graphene material are uniformly attached within the porous cavity composite material 19, with the iron powder being millimeter-sized. When the coil of the electromagnetic heating device 8 is connected to AC power, the generated high-frequency alternating magnetic field causes eddy currents in the millimeter-sized iron powder within the porous cavity composite material 19, releasing heat. The nano-peroxide graphene material helps accelerate heat conduction. The heat causes the phase-change liquid within the porous cavity composite material 19 to vaporize, increasing the air pressure within the flexible sealing airbag. This overcomes the resistance torque of the elastic sheet, allowing the joint to unfold and enabling the leg 1 to extend and paddle. When heating stops, the joint cools naturally under the water flow and retracts under the torque of the elastic sheet, returning the leg to a bent state. By re-energizing the electromagnetic coil and repeating the above process, the leg 1 can repeatedly paddle, enabling the frog-like soft robot to simulate the swimming motion of a real frog's joints.

[0047] In nature, it can be observed that frogs' webbed feet can open and close, thereby changing the area of ​​the webbed feet and thus changing the resistance when swimming. This mechanism greatly improves their swimming efficiency. Inspired by this biological mechanism, the above-mentioned rolled bionic webbed feet 4 were proposed.

[0048] like Figure 3 , 4 As shown, a sealing plastic film is used as the outer wrapping material for the rolled bionic flippers 4. An elastic rolled steel sheet 16 is tightly adhered to the sealing plastic film to provide a rewinding force for the rolled bionic flippers 4, so that the rolled bionic flippers 4 are in a contracted state in the initial state. The bionic flippers 18 have a small area and are fixed to the outside of the leg 1 with hot melt adhesive. The sealed plastic film is filled with a low-temperature phase change material, hexafluorobutene, and 4-6 ceramic heating elements 14 are arranged at intervals. Each ceramic heating element 14 is led out by two wires 17 and connected to a switching power supply inside the frog's shell. The ceramic heating elements 14 are in direct contact with the phase change liquid and heat the low-temperature phase change material through the ceramic heating elements 14.

[0049] When the frog-like soft robot swims, the bionic joints 9 of the legs 1 extend and open, while the ceramic heating plate 14 is heated by electricity. This causes the low-temperature phase change material to vaporize rapidly, thereby extending the curled bionic flippers 4 and increasing the area that the legs 1 glide across in the water during paddling. When the bionic joints 9 retract and the legs 1 return to their bent state, the curled bionic flippers 4 retract and return to the contracted state of the bionic flippers 18, reducing the area of ​​the legs 1 and thus reducing water resistance, thereby effectively improving the swimming efficiency of the frog-like soft robot.

[0050] When the frog-like soft robot needs to turn, the control module 5 controls the energization and de-energization of the ceramic heating elements 14 in the coiled bionic flippers 4 on both sides. This creates a difference in the area of ​​the flippers on both sides, resulting in a power difference and thus achieving the purpose of turning. For example, when turning left, the control module 5 disconnects the left wire and connects the right wire; the opposite is true when turning right.

[0051] The legs 1 of the frog-like soft robot are integrally connected to the elastic sheet of the simulated joint 9. Both the legs 1 and the elastic sheet are thin sheet structures made of PLA material through 3D printing. The legs 1 not only serve as the body structure of the frog-like soft robot, but also enable the actuation and recovery of the bionic joint 9, achieving both structural compactness and functional integration.

[0052] like Figure 5 , 6 As shown, the biomimetic swim bladder 10 includes three sealed plastic air bladders 21 with a sandwich structure. A first chamber 20 is formed between the upper and middle layers, and a second chamber 22 is formed between the middle and lower layers. A copper-based graphene sheet 23 is disposed in the middle of the first chamber 20 and the second chamber 22. Both the first chamber 20 and the second chamber 22 are filled with low-temperature phase change material. A miniature temperature sensor is placed inside the low-temperature phase change material, and the temperature sensor is electrically connected to the control module 5 inside the frog's shell. Different sizes of biomimetic swim bladders 10 are equipped with different colored borders 24. The copper-based graphene sheet 23 is black and its function is to absorb laser energy and convert it into heat to heat the low-temperature phase change material. The colored borders 24 help locate the position of the biomimetic swim bladder 10. Simultaneously, different colored borders 24 represent different sizes of biomimetic swim bladders 10, corresponding to different maximum buoyancy. Specifically, the red border represents the large bionic swim bladder 10 (3x5cm, 0.8N), the green border 24 represents the medium bionic swim bladder 10 (2x3cm, 0.2N), and the blue border represents the small bionic swim bladder 10 (1x3cm, 0.1N). All bionic swim bladders 10 are fixed to the upper surface of the frog's outer shell using silicone glue.

[0053] like Figure 9 As shown, a shore-based control system is also installed on the water's edge of the frog-like soft robot. This shore-based control system can communicate with the control module 5 inside the frog's shell via electromagnetic waves. The shore-based control system includes a PID controller, a servo gimbal, a laser emitter, a camera, and a PC for the user.

[0054] Both the laser emitter and the camera are fixed to a servo gimbal. Different sized bionic swim bladders 10 are equipped with colored borders 24 made of paper of corresponding colors, with each color representing the maximum buoyancy of the swim bladder 10. The onshore camera uses machine vision technology to identify the color of the swim bladder 10's border, extracting information and locating the black heating area. The camera's identification of the swim bladder 10's border color and the location information of the copper-based graphene sheet 23 can be transmitted in real-time to a PID controller via a PC to further adjust the servo gimbal's rotation, ensuring that the camera and laser emitter are aligned with the swim bladder 10. Users can use the onshore control system to emit a laser to heat the copper-based graphene sheet 23 on any of the bionic swim bladders 10 on the frog's outer shell, generating the required buoyancy.

[0055] The specific process is as follows: The PC transmits data to the PID controller. The PID controller adjusts the rotation angle of the servo gimbal based on the data and information provided by the camera and the user, thereby adjusting the pointing position of the laser emitter and sending an on or off signal to the laser emitter. When the laser is emitted, it mainly irradiates the copper-based graphene sheet 23 inside the biomimetic swim bladder 10. The copper-based graphene sheet 23 absorbs the laser energy and converts it into heat to heat the low-temperature phase change material, causing the low-temperature phase change material to vaporize rapidly. This increases the volume of the biomimetic swim bladder 10, thereby increasing the buoyancy of the frog-like soft robot. After heating stops, the biomimetic swim bladder 10 cools rapidly and shrinks in volume under the cooling effect of natural water, thereby reducing buoyancy and enabling the frog-like soft robot to sink. In addition, the temperature sensor inside the bionic swim bladder 10 collects temperature information and transmits it to the control module 5. After being processed by the microprocessor of the control module 5, the signal is transmitted back to the PID controller of the onshore control system via a radio electromagnetic wave communicator, and then fed back to the PC and the user to achieve closed-loop control, thereby achieving the purpose of fast response and precise temperature control.

[0056] like Figure 7 , 8 As shown, the bistable gripper 12 includes a bistable spring 26, a silicone hose 25, a miniature electromagnet, a corrugated flexible brake, and a ceramic heating element. The bistable spring 26 includes three sets, which are fixedly connected to the bottom of the frog's shell through a three-in-one rod. Corrugated flexible brakes are installed on the inner and outer sides of each set of bistable springs 26. The inner corrugated flexible brake 27 and the outer corrugated flexible brake 28 are filled with a low-temperature phase change liquid and a ceramic heating element. The silicone hose 25 is filled with a mixed liquid metal and a ceramic heating element for heating it.

[0057] The mixed liquid metal is a gallium-iron alloy, which has a low melting point and is filled in a silicone tubing 25. A ceramic heating element is connected to the robot's internal power module via wires, directly contacting the gallium-iron alloy. When the ceramic heating element is energized and releases heat, it keeps the gallium-iron alloy in a liquid state. The silicone tubing 25 has better biocompatibility, which can prevent harm to living organisms to some extent.

[0058] The bistable spring 26 is initially in a stable state with its arms outward. When the control module 5 issues a command, the ceramic heating element on the outer side of the bistable spring 26 is energized, while the ceramic heating element on the inner side is de-energized. This heats and vaporizes the low-temperature phase change liquid inside the outer pleated flexible brake 28, increasing the air pressure inside the outer pleated flexible brake 28. This generates mechanical force to overcome the spring's resistance, causing the spring to deform inward. The spring can act as an energy storage device to store elastic potential energy. When the deformation exceeds a critical value, the spring will rapidly release the elastic potential energy and deform inward, transforming into a stable state with its arms outward, causing the bistable gripper 12 to close. After the gripper closes, the control module 5 issues a command to energize the micro electromagnet to generate a magnetic field. The mixed liquid metal inside the silicone hose 25 is exposed to the magnetic field and will solidify, exhibiting the mechanical properties of a solid, thereby achieving the purpose of locking the bistable gripper 12. When the gripper is locked, the outer ceramic heating element will stop heating. Under the natural cooling effect of water, the gas inside the outer pleated flexible brake 28 will liquefy, and the air pressure will also decrease.

[0059] When the gripper needs to be released, the control module 5 will send a command to de-energize the miniature electromagnet and energize the ceramic heating element inside the bistable spring 26 to heat the low-temperature phase change material, causing the bistable spring 26 to deform outward, thereby releasing the gripper. If the gripper does not need to be released for an extended period, the control module 5 will send a command to stop the heating of the ceramic heating element inside the silicone hose 25. Under the natural cooling effect of water, the alloy temperature will drop below the melting point and solidify. After this, the electromagnet can be de-energized, achieving long-term locking of the gripper and saving energy. If the gripper needs to be released later, the alloy can be reheated and the inner ceramic heating element energized again.

[0060] like Figure 2 As shown, an underwater camera 7, an ultrasonic detector 6, and a GPS locator are installed on the head of the frog's exoskeleton. A power module 13 is located inside the exoskeleton. The underwater camera 7 captures underwater images to determine the location of underwater objects and targets. The ultrasonic detector 6 detects underwater obstacles, allowing the robot to steer and avoid them using its coiled bionic flippers 4. The GPS locator pinpoints the location of the frog-like soft robot. The power module supplies power to the ultrasonic detector 6, GPS locator, and other components.

[0061] Specifically, the ultrasonic detector 6 emits ultrasonic waves of a specific frequency when the robot moves. When these ultrasonic waves encounter an object, they are reflected and captured by a receiving device. By analyzing the time and direction of the reflected waves, the distance and direction between the object and the robot can be determined, thereby calculating the object's coordinates. This coordinate information is then sent to the control module 5, enabling precise obstacle avoidance or target object tracking.

[0062] The underwater camera 7 at the front of the frog-like soft robot transmits real-time images of its surrounding environment to the user's PC. The user can plan and control the frog-like soft robot's movement to grasp target objects and avoid obstacles.

[0063] Simultaneously, the GPS locator acquires and sends the robot's current location information to control module 5, which is then transmitted via electromagnetic waves to the onshore control system and displayed on the user's PC. When the frog-like soft robot approaches the target object at a suitable angle along the path planned by the processor, the user can issue a command to control the gripper to close or open, capturing the target object.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A frog-like soft robot based on gas-liquid phase change, characterized in that, include: The frog body shell consists of a frog shell, legs, and a bistable gripper. The two sides of the frog shell are connected to the legs via bionic joints. The outer sides of the legs are fitted with rolled bionic webs. The frog shell contains a control module, an electromagnetic heating device, and buoyancy foam. The top of the frog shell has multiple bionic swim bladders. The bistable gripper is fixedly connected to the bottom of the frog shell. The bionic joint includes an elastic sheet integrally connected to the leg. A flexible sealing airbag is attached to one side of the elastic sheet. The flexible sealing airbag contains a porous composite material with iron powder attached and filled with a low-temperature phase change material. The iron powder can generate eddy currents and release heat under the action of the high-frequency alternating magnetic field generated by the electromagnetic heating device. The low-temperature phase change material vaporizes, causing the air pressure of the flexible sealing airbag to increase, overcome the resistance of the elastic sheet, and unfold, so as to realize the extension and paddling of the leg. The coiled bionic flippers include an elastic coiled steel sheet and a sealed plastic film bonded to it. The sealed plastic film is filled with a low-temperature phase change material and is provided with ceramic heating plates arranged at intervals. The ceramic heating plates can heat the low-temperature phase change material to vaporize and fill the sealed plastic film, so that it and the elastic coiled steel sheet can unfold together. The biomimetic swim bladder includes multiple layers of sealed plastic airbags, forming multiple chambers. The top and bottom chambers are filled with low-temperature phase change material, and a copper-based graphene sheet is disposed in the middle of the low-temperature phase change material. The copper-based graphene sheet can absorb laser heat to vaporize the low-temperature phase change material and fill the sealed plastic airbags, thereby increasing its volume and enabling it to float.

2. The frog-like soft robot based on gas-liquid phase change according to claim 1, characterized in that, The low-temperature phase change material is hexafluorobutene.

3. The frog-like soft robot based on gas-liquid phase change according to claim 1, characterized in that, An adjustment block is provided inside the frog's outer shell. An adjustment screw passes through the adjustment block and is threadedly connected to it. The two ends of the adjustment screw are fixedly connected to the inner wall of the frog's outer shell.

4. The frog-like soft robot based on gas-liquid phase change according to claim 1, characterized in that, The cavity porous composite material also contains nano-peroxygenated graphene material. The iron powder and the nano-peroxygenated graphene material are uniformly attached to the cavity porous composite material, and the iron powder is in the millimeter scale.

5. The frog-like soft robot based on gas-liquid phase change according to claim 1, characterized in that, The frog's body shell is equipped with an underwater camera, ultrasonic detector, and GPS locator on its head.

6. The frog-like soft robot based on gas-liquid phase change according to claim 1, characterized in that, The leg is integrally connected to the elastic sheet, and both the leg and the elastic sheet are sheet structures made of PLA material through 3D printing.

7. The frog-like soft robot based on gas-liquid phase change according to claim 1, characterized in that, The biomimetic swim bladder comprises three sealed plastic air bladders, with a first chamber formed between the upper and middle layers, and a second chamber formed between the middle and lower layers. The copper-based graphene sheet is disposed in the middle of the first and second chambers. Both the first and second chambers are filled with low-temperature phase change material, and a temperature sensor is placed inside the low-temperature phase change material. The temperature sensor is electrically connected to the control module. Biomimetic swim bladders of different sizes are provided with borders of different colors.

8. The frog-like soft robot based on gas-liquid phase change according to claim 7, characterized in that, It also includes a shore-based control system, which includes a PID controller, a servo gimbal, a laser emitter, a camera, and a PC. The camera can identify the border color of the bionic swim bladder and locate the position of the copper-based graphene sheet. It transmits the color and position information data to the PID controller in real time through the PC, which controls the rotation of the servo gimbal so that the camera and the laser emitter are aligned with the bionic swim bladder. This heats the copper-based graphene sheet on the bionic swim bladder to generate the required buoyancy.

9. The frog-like soft robot based on gas-liquid phase change according to claim 1, characterized in that, The bistable gripper includes a bistable spring, a silicone tube, a miniature electromagnet, a corrugated flexible actuator, and a ceramic heating plate. The bistable spring comprises three sets, each fixedly connected to the bottom of the frog's outer shell via a rod. The corrugated flexible actuator is installed on the inner and outer sides of each set of bistable springs. The corrugated flexible actuator contains a low-temperature phase-change liquid and the ceramic heating plate. The silicone tube is filled with a mixed liquid metal. Initially, the bistable spring is in a stable, outward-opening state. Heating the low-temperature phase-change liquid within the outer corrugated flexible actuator by the ceramic heating plate increases the internal pressure, causing the bistable spring to deform inward and transform into an inward-facing stable state, thus closing the bistable gripper. The miniature electromagnet, when energized, generates a magnetic field that solidifies the mixed liquid metal within the silicone tube, thereby locking the bistable gripper in place.

10. The frog-like soft robot based on gas-liquid phase change according to claim 9, characterized in that, The mixed liquid metal is a gallium-iron alloy.

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