Variable stiffness amphibious drive system based on magneto-fluidic seal and pneumatic biomimicry

Abstract

The application provides a variable stiffness amphibious driving system based on magnetic fluid sealing and pneumatic bionics, and belongs to the technical field of amphibious driving, and comprises a magnetic fluid sealing joint, a pneumatic muscle joint and a tail joint, the magnetic fluid sealing joint and the pneumatic muscle joint constitute a connecting mechanism, one end of the tail joint is connected with a wheel hub through the connecting mechanism, one end of the wheel hub is provided with a power joint, the wheel hub is fixedly connected with the power joint, one end of the power joint is connected with a wheel hub rotor through the connecting mechanism, one end of the wheel hub rotor is provided with an encapsulation joint, the wheel hub rotor is fixedly connected with the encapsulation joint, and the encapsulation joint is connected with a front joint through the connecting mechanism. The variable stiffness amphibious driving system based on magnetic fluid sealing and pneumatic bionics is adopted, and efficient driving and reliable sealing of the amphibious system under multiple working conditions are realized.

Description

Technical Field

[0001] This invention relates to the field of amphibious drive technology, and in particular to a variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic biomimicry. Background Technology

[0002] The key to developing amphibious biomimetic propulsion systems lies in balancing the complex relationship between the actuation flexibility of multi-degree-of-freedom joints, dynamic sealing reliability, and cross-environment adaptability. Traditional systems often struggle to simultaneously meet these three core requirements during design, resulting in limited performance in practical applications and failing to fully realize the potential advantages of amphibious devices.

[0003] In existing technologies, some systems employ a three-degree-of-freedom joint combined with gear-servo drive and a modular structure to improve system flexibility and maintainability. Traditional servos rely on gear transmission, which, while providing precise control, suffers from high energy consumption and low flexibility, making it difficult to adapt to changing environmental demands. Meanwhile, while dielectric elastomer flexible drive technology offers high energy efficiency and controllable deformation characteristics, it lacks an effective variable stiffness mechanism, failing to achieve dynamic switching between joint rigidity and flexibility, thus limiting the system's adaptability to different environments.

[0004] Regarding the sealing of underwater joints, static flange seals or waterproof sleeves are currently commonly used. However, these sealing methods are prone to leakage due to wear or deformation under dynamic multi-axis motion, severely affecting the reliability and durability of the system. Most existing biomimetic propulsion systems are designed for single operating conditions, such as dedicated underwater thrusters or land-based crawling structures. Their sealing and propulsion solutions often fail to meet the different requirements of both aquatic and terrestrial environments simultaneously. In particular, during the transition between water and land, significant changes in loads such as fluid resistance and terrain friction can lead to a substantial decrease in system motion efficiency and stability.

[0005] Therefore, developing an innovative solution that integrates magnetohydrodynamic sealing technology, variable stiffness bionic joint modules, and cross-environment motion control systems is of great significance for achieving efficient drive and reliable sealing of amphibious systems under multiple operating conditions. Summary of the Invention

[0006] The purpose of this invention is to provide a variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic biomimetic technology, which breaks through the limitations of traditional technology and meets the requirements of efficient, reliable and multifunctional amphibious crawling system design, realizing efficient drive and reliable sealing of amphibious system under multiple working conditions.

[0007] To achieve the above objectives, the present invention provides a variable stiffness amphibious drive system based on magnetohydrodynamic sealing and pneumatic bionics, including a magnetohydrodynamic sealing joint, a pneumatic muscle joint, and a tail joint. The magnetohydrodynamic sealing joint and the pneumatic muscle joint form a connecting mechanism. One end of the tail joint is connected to the wheel through the connecting mechanism. One end of the wheel is provided with a power joint. The wheel is fixedly connected to the power joint. One end of the power joint is connected to the wheel rotor through the connecting mechanism. One end of the wheel rotor is provided with an encapsulation joint. The wheel rotor is fixedly connected to the encapsulation joint. The encapsulation joint is connected to the front joint through the connecting mechanism.

[0008] Preferably, the magnetic fluid sealing joint includes an annular permanent magnet and an electromagnet shaft, the electromagnet shaft passing through the interior of the annular permanent magnet, the space between the electromagnet shaft and the annular permanent magnet being filled with magnetic fluid, and a resonant coil being disposed inside the electromagnet shaft.

[0009] Preferably, the annular permanent magnet includes an N-pole shoe, a permanent magnet, and an S-pole shoe, with the permanent magnet recessed inward and an N-pole shoe and an S-pole shoe respectively provided at both ends of the permanent magnet.

[0010] Preferably, the pneumatic muscle joint includes an externally covered tough film with a built-in micro pressure sensor and an internal air bladder. Four air pumps are arranged in the center of the air bladder, and magnetic fluid sealing couplings are arranged between the air pumps on opposite sides. The air pumps on opposite sides are fixedly connected by the magnetic fluid sealing couplings, and magnetic fluid sealing filling grooves are provided on the magnetic fluid sealing couplings.

[0011] Preferably, the tail joint includes an internally integrated micro motor and power module, and a magnetohydrodynamic (MHD) sealed joint is connected to the front end of the tail joint. The internally integrated micro motor and power module drive the electromagnet shaft, and the resonant coil inside the MHD sealed joint generates a correlated magnetic field with the resonant coil of the next MHD sealed joint to transfer energy.

[0012] Preferably, the power joint includes an electromagnetic clutch and a shape memory alloy drive element;

[0013] The shape memory alloy driving element includes a motor, with a front output shaft and a rear output shaft respectively at both ends of the motor. The motor is connected to a second sun gear through the front output shaft and to a first sun gear through the rear output shaft. The second sun gear is meshed with a first gear ring, and the first sun gear is meshed with the second gear ring. A large outer gear ring and planetary gears are provided on the outside of the first sun gear, and the first sun gear is meshed with the large outer gear ring through the planetary gears.

[0014] The electromagnetic clutch is mounted on the planetary gear, the second ring gear, and the first sun gear.

[0015] Preferably, a shape memory alloy with a built-in resistance wire is provided on the outer side of the first gear ring, and the shape memory alloy is fixedly connected to the first gear ring through a fixed shaft.

[0016] Therefore, the present invention employs the aforementioned variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic biomimicry, and the technical effects are as follows:

[0017] 1. Significantly improves dynamic sealing reliability: By introducing a magnetohydrodynamic sealing device into the joint rotating shaft system to replace the traditional O-ring or contact mechanical seal, the wear and aging problems under high-speed rotation conditions are effectively overcome, enabling the system to work stably in a high-pressure underwater environment for a long time, greatly extending the seal life and reducing maintenance requirements.

[0018] 2. Achieving adaptive stiffness adjustment and enhanced environmental adaptability: The biomimetic steering joint is constructed using pneumatic muscle components. By utilizing its inherent aerodynamic variable stiffness characteristics and combining multi-sensor information feedback and closed-loop control algorithms, the joint can adjust its stiffness in real time according to the load changes of the external water or land environment, thus possessing both driving flexibility and anti-disturbance capabilities.

[0019] 3. Achieving Multimodal Drive and Rapid Environmental Switching: A mode-switching differential mechanism, composed of shape memory alloy (SMA) drive elements and an electromagnetic clutch, enables active and controllable switching between land and water drive modes. The displacement of the drive elements under thermal actuation coordinates with the clutch action, ensuring the reliability and response speed of the mode switching process.

[0020] 4. High integration and system simplification: The wireless integrated power joint design integrates the drive motor, reduction mechanism and sensing unit into a sealed joint housing, and realizes non-contact transmission of energy and signals based on electromagnetic induction wireless transmission technology, which simplifies the overall system structure and improves modularity and watertight reliability. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall structure of the variable stiffness amphibious drive system of the present invention;

[0022] Figure 2 This is a schematic diagram of the magnetohydrodynamic sealing joint structure of the present invention;

[0023] Figure 3 This is a schematic diagram of the pneumatic muscle joint structure of the present invention;

[0024] Figure 4 This is a schematic diagram of the tail joint structure of the present invention;

[0025] Figure 5 This is a schematic diagram of the full cross-sectional structure of the encapsulated joint of the present invention;

[0026] Figure 6 This is an isometric view of the joint after the gear ring has been removed in this invention.

[0027] Figure Labels

[0028] 1. Magnetohydrodynamic (MHD) sealed joint; 2. Encapsulated joint; 3. Meyer wheel rotor; 4. Pneumatic muscle joint; 5. Power joint; 6. Meyer wheel; 7. Tail joint; 8. Small propeller; 11. N pole shoe; 12. Permanent magnet; 13. S pole shoe; 14. Electromagnetic shaft; 15. Magnetohydrodynamic (MHD); 16. Resonant coil; 211. First gear ring; 212. Second gear ring; 231. Rear output shaft; 232. Front output shaft; 241. First sun gear; 242. Second sun gear; 25. Motor; 26. Shape memory alloy; 27. Fixed shaft; 28. Resistance wire; 221. Peripheral large gear ring; 222. Planetary gear; 41. Tough thin film with built-in micro pressure sensor; 42. Magnetohydrodynamic (MHD) sealed coupling; 421. Magnetohydrodynamic (MHD) sealed filling groove; 43. Air pump; 44. Airbag; 71. Integrated micro motor and power module. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0031] Example 1

[0032] like Figure 1 As shown, this invention provides a variable stiffness amphibious drive system based on magnetohydrodynamic sealing and pneumatic bionics, including a magnetohydrodynamic sealing joint 1, a pneumatic muscle joint 4, and a tail joint 7. The magnetohydrodynamic sealing joint 1 and the pneumatic muscle joint 4 form a connecting mechanism. One end of the tail joint 7 is connected to a wheel 6 through the connecting mechanism. One end of the wheel 6 is provided with a power joint 5. The wheel 6 and the power joint 5 are fixedly connected. One end of the power joint 5 is connected to a wheel rotor 3 through the connecting mechanism. One end of the wheel rotor 3 is provided with an encapsulation joint 2. The wheel rotor 3 and the encapsulation joint 2 are fixedly connected. The encapsulation joint 2 is connected to the front joint through the connecting mechanism.

[0033] like Figure 2As shown, the magnetofluid sealing joint 1 includes an annular permanent magnet 12 and an electromagnet shaft 14. The annular permanent magnet 12 is set at the joint connection. The annular permanent magnet 12 includes an N pole shoe 11, a permanent magnet 12, and an S pole shoe 13. The permanent magnet 12 is recessed inward, and the N pole shoe 11 and S pole shoe 13 are respectively set at both ends of the permanent magnet 12. The electromagnet shaft 14 passes through the interior of the annular permanent magnet 12. Magnetofluid 15 is filled between the electromagnet shaft 14 and the annular permanent magnet 12. Under normal circumstances, the magnetic field generated by the external annular permanent magnet 12 is used to completely fill the gap with magnetofluid 15 to seal it. When encountering high pressure or collision that causes changes in the internal gap, the control magnetic field generated by energizing the electromagnet shaft 14 changes the compression state of the magnetofluid 15, thereby changing the thickness of the magnetofluid 15. Under high pressure, a positive current is passed to activate the magnetic field enhancement mode, and the magnetofluid 15 is tightly bound, making the sealing ring "thin" and concentrated. Under low pressure, a reverse current is passed to activate the magnetic field weakening mode, and the magnetic fluid 15's adsorption force weakens, making the sealing ring "wider" and diffused.

[0034] Magnetofluidic sealing technology is integrated at the joint's rotating shaft location, replacing traditional O-rings or mechanical seals. By adjusting the thickness of the magnetofluidic sealing layer 15 using a magnetic field, effective sealing can be maintained under high-speed rotation and high-pressure underwater conditions, significantly reducing friction loss and improving sealing reliability. The magnetofluidic sealed joint 1 utilizes the sealing characteristics of the magnetofluid 15 under the action of a magnetic field to achieve dynamic sealing of the rotating shaft, preventing liquid or gas leakage.

[0035] like Figure 3 As shown, a pneumatic muscle joint is used instead of a servo motor as the steering actuator. The pneumatic muscle joint 4 includes an externally covered, resilient diaphragm 41 with a built-in micro pressure sensor and an internally divided, cross-shaped four air bladders 44. Four air pumps 43 are arranged in the center, and the joint flexibility and angle are controlled by adjusting the air pressure. A magnetic fluid sealing coupling 42 is provided between the air pumps 43 on opposite sides, and the air pumps 43 on opposite sides are fixedly connected by the magnetic fluid sealing coupling 42. The magnetic fluid sealing coupling 42 is provided with a magnetic fluid sealing filling groove 421 to improve the sealing reliability.

[0036] For variable stiffness adjustment, a flexible diaphragm 41 with a built-in micro-pressure sensor collects ambient pressure values ​​in real time and feeds them back to the control center. The control center receives these values ​​in real time and adjusts the pressure inside the airbag 44 by controlling the output of the corresponding air pump 43, thus dynamically adjusting its stiffness. For steering design, for example, when turning left, the upper and lower airbags 44 remain unchanged, while the air pressure of the right airbag 44 is reduced and the air pressure of the left airbag 44 is increased, creating a pressure difference that drives the joint to bend to the left. The opposite is true for reverse steering.

[0037] The pneumatic muscle joint 4 generates driving force through the expansion and contraction of the air bladder 44, driving the system to move. Combined with built-in micro pressure sensors and feedback control algorithms, it dynamically adjusts the stiffness of the joint to adapt to different environmental loads.

[0038] like Figure 4 As shown, the tail joint 7 includes an internally integrated micro motor and power module 71. A magnetohydrodynamic (MHD) sealed joint 1 is connected to the front end of the tail joint 7. The internally integrated micro motor and power module 71 drive the electromagnet shaft 14. The resonant coil 16 inside the MHD sealed joint 1 generates a correlated magnetic field with the resonant coil 16 of the next MHD sealed joint 1 to transfer energy. Wireless power supply is achieved using the principle of electromagnetic conversion, and the energy is then transferred to the next section.

[0039] like Figures 5-6 As shown, the power joint 5 includes an electromagnetic clutch and a shape memory alloy drive element. The power joint 5 generates thrust by rotating to drive the system forward or turn. The shape memory alloy (SMA) drive element, combined with the electromagnetic clutch, enables the system to seamlessly switch between water and land modes.

[0040] The shape memory alloy driving element includes a motor 25, with a front output shaft 232 and a rear output shaft 231 at both ends. The motor 25 is connected to a second sun gear 242 via the front output shaft 232 and to a first sun gear 241 via the rear output shaft 231. The second sun gear 242 is meshed with a first gear ring 211, and the first sun gear 241 is meshed with the second gear ring 212. A peripheral large gear ring 221 and a planetary gear 222 are provided on the outside of the first sun gear 241, and the first sun gear 241 is meshed with the peripheral large gear ring 221 via the planetary gear 222. A shape memory alloy (SMA) 26 with an internal resistance wire 28 is provided on the outside of the first gear ring 211, and the shape memory alloy (SMA) 26 is fixedly connected to the first gear ring 211 via a fixed shaft 27.

[0041] The electromagnetic clutch is mounted on the planetary gear 222, the second ring gear 212, and the first sun gear 241.

[0042] The design incorporates a differential gear set with an electromagnetic clutch and a shape memory alloy drive element to achieve multi-mode switching for amphibious use. In land mode, the front output shaft 232 moves backward, the first sun gear 241 meshes and locks with the planetary gear set 222, while the second sun gear 242 fixed on the shaft disengages. The motor 25 drives the wheel 6 to achieve high-torque wheel drive. The resistance wire 28 heats the shape memory alloy (SMA) 26 to rotate and contract around the fixed shaft 27 to form a joint support. In underwater mode, the current of the electromagnetic clutch reverses, the first sun gear 241 and the planetary gear 222 are decoupled and attracted and engaged by the second gear ring 212. The rear output shaft 231 moves forward and drives the front output shaft 232, so that the second sun gear 242 is engaged with the first gear ring 211. The motor 25 simultaneously drives the McLaren rotor 3 and the power joint (large propeller) 5. The resistance wire 28 cools and causes the shape memory alloy (SMA) 26 to rotate around the fixed shaft 27, recover and extend to form the power joint (large propeller) 5 to provide the main force. At the same time, the McLaren rotor 3 decouples and pops out to form the small propeller 8, realizing the fine control of direction and speed.

[0043] The workflow of this amphibious drive system is as follows:

[0044] Initially launched on land, the robot's joints are sealed using magnetohydrodynamics 15. Shape memory alloy (SMA) 26 outside the joints senses ambient temperature and contracts to form joint support. Simultaneously, integrated micro-motors and power modules 71 within the front and tail joints 7 operate, driving the electromagnet shaft 14 within the magnetohydrodynamically sealed joint 1 at the connection point. Wireless power is supplied using the associated magnetic field and electromagnetic induction principle of the resonant coils 16 between the joints. Next, the flexible thin film 41 of the built-in micro-pressure sensor in the pneumatic muscle joint 4 senses external pressure and feeds it back to the control center. The control center analyzes the data, heats the resistance wire 28 built into the shape memory alloy (SMA) 26 to cause it to contract and form joint support, and controls the pneumatic muscle joint 4 to inflate until it is balanced with the external environment. Simultaneously, the front output shaft 232 and rear output shaft 231 within the power joint 5 move backward and mesh with the planetary gear 222. The motor 25 drives the wheel 6, using the pressure difference between the various air bladders 44 within the pneumatic muscle joint 4 for steering.

[0045] During initial underwater startup, the resistance wire 28 is not heated. The shape memory alloy (SMA) 26 outside the joint unfolds to form a large propeller. Simultaneously, the pneumatic muscle joint 4 senses changes in environmental pressure and feeds them back to the control center. After analysis, the control center adjusts the stiffness of the pneumatic muscle, controls the decoupled rotor 3 to form a small propeller 8, and controls the front output shaft 232 and rear output shaft 231 inside the power joint 5 to move forward, so that they mesh with the second gear ring 212 and the first gear ring 211 respectively. The motor 25 simultaneously drives the shape memory alloy (SMA) 26 and the rotor 3. If subjected to pressure shocks underwater, the control center receives feedback and controls the magnetohydrodynamic sealing joint 1 to change the sealing thickness of the magnetohydrodynamic 15 accordingly to ensure complete sealing.

[0046] Therefore, the present invention adopts the above-mentioned variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic bionics, integrating magnetohydrodynamic dynamic sealing technology, variable stiffness aerodynamic bionic joint, wireless integrated power joint and shape memory alloy (SMA) multi-modal switching differential mechanism, aiming to solve the contradiction between drive flexibility, sealing reliability and cross-environmental adaptability in existing amphibious systems, and has excellent environmental adaptability, drive flexibility and system reliability.

[0047] 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 preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic biomimicry, characterized in that, It includes a magnetohydrodynamic sealing joint, a pneumatic muscle joint, and a tail joint. The magnetohydrodynamic sealing joint and the pneumatic muscle joint form a connecting mechanism. One end of the tail joint is connected to the wheel through the connecting mechanism. One end of the wheel is provided with a power joint. The wheel is fixedly connected to the power joint. One end of the power joint is connected to the wheel rotor through the connecting mechanism. One end of the wheel rotor is provided with a sealing joint. The wheel rotor is fixedly connected to the sealing joint. The sealing joint is connected to the front joint through the connecting mechanism. The magnetic fluid sealed joint includes an annular permanent magnet and an electromagnet shaft. The space between the electromagnet shaft and the annular permanent magnet is filled with magnetic fluid, and a resonant coil is installed inside the electromagnet shaft. The pneumatic muscle joint includes an externally covered tough film with built-in micro pressure sensors and an internal air bladder. Four air pumps are set in the center of the air bladder, and magnetic fluid sealing couplings are set between the air pumps on opposite sides. Magnetic fluid sealing couplings are set with magnetic fluid sealing filling grooves. The tail joint includes an internally integrated micro motor and power module. The resonant coil inside the magnetohydrodynamic sealed joint and the resonant coil of the next magnetohydrodynamic sealed joint generate a correlated magnetic field to transfer energy. The power joint includes an electromagnetic clutch and a shape memory alloy drive element. The shape memory alloy drive element includes a motor, a second sun gear, a first sun gear, a first gear ring, a second gear ring, a peripheral large gear ring, and planetary gears. The electromagnetic clutch is mounted on the planetary gears, the second gear ring, and the first sun gear. The outer side of the first gear ring is provided with a shape memory alloy with built-in resistance wire.

2. The variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic biomimicry according to claim 1, characterized in that, The electromagnet shaft passes through the interior of the ring-shaped permanent magnet.

3. The variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic biomimicry according to claim 1, characterized in that, The ring-shaped permanent magnet includes an N-pole shoe, a permanent magnet, and an S-pole shoe. The permanent magnet is recessed inward, and the N-pole shoe and S-pole shoe are respectively provided at both ends of the permanent magnet.

4. The variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic biomimicry according to claim 1, characterized in that, The air pumps on opposite sides are fixedly connected via a magnetohydrodynamic sealing coupling.

5. The variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic biomimicry according to claim 1, characterized in that, The tail section has a magnetohydrodynamic sealed joint at the front end, and an integrated micro motor and power module drive the electromagnet shaft.

6. The variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic biomimicry according to claim 1, characterized in that, The motor has a front output shaft and a rear output shaft at both ends. The motor is connected to the second sun gear through the front output shaft and to the first sun gear through the rear output shaft. The second sun gear is meshed with the first ring gear, and the first sun gear is meshed with the second ring gear. A large outer ring gear and planetary gears are provided on the outside of the first sun gear. The first sun gear is meshed with the large outer ring gear through the planetary gears.

7. The variable stiffness amphibious drive system based on magnetohydrodynamic sealing and aerodynamic biomimicry according to claim 1, characterized in that, The shape memory alloy is fixedly connected to the first gear ring via a fixed shaft.

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