Cross-medium unmanned aerial vehicle based on active torque buffer device

Abstract

The invention discloses a cross-medium unmanned aerial vehicle based on an active torque buffer device. The unmanned aerial vehicle adopts a power system integrated active torque buffering scheme, has the characteristics of simple system topology and low power consumption, and can effectively improve the load efficiency and energy efficiency of the whole vehicle. By adjusting the electromagnetic state in the active torque buffer device, the stiffness characteristic of the power system is dynamically changed through the magneto-rheological effect, and cross-medium whole-process power connection is achieved. Compared with a configuration equipped with an independent underwater propulsion unit or buoyancy adjusting mechanism, the scheme has the advantages that mode adjustment or mechanical mode switching is not needed when the unmanned aerial vehicle passes through the water-air interface, and continuity and dynamic response of task execution are ensured. Meanwhile, an active torque buffering mechanism can effectively absorb transient impact loads generated by medium sudden change, a driving motor and a fuselage structure are protected against damage, and the operation reliability and control robustness of the unmanned aerial vehicle in the complex fluid environment are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of cross-medium unmanned aerial vehicles (UAVs) and their accessories, and more specifically to a cross-medium UAV based on an active torque buffer device. Background Technology

[0002] Cross-medium unmanned aerial vehicles (UAVs) are aircraft capable of moving between air and water, and are used in underwater exploration, environmental monitoring, and other fields. Due to the significant differences in density, viscosity, and fluid drag characteristics between air and water, the rotor faces complex dynamic processes when crossing the air-liquid interface, including abrupt changes in flow field, rapid changes in added mass, and the superposition of fluid adhesion effects. Especially at the moment the rotor enters or exits the water, the counter-torque and drag experienced by the propeller change abruptly, causing rapid fluctuations in the motor's output torque, which in turn leads to attitude disturbances and control instability. Existing cross-medium UAVs generally mitigate these problems by configuring water-air separation propulsion systems, but in actual operation, it is still difficult to effectively suppress the transient impact caused by torque abrupt changes, resulting in discontinuous operation.

[0003] For example, patent application number 202010537869.5 discloses a cross-medium amphibious unmanned aerial vehicle (UAV) whose power system employs two independent power schemes: an aerial quadcopter and an underwater thruster. This scheme requires switching between aerial and underwater power for cross-medium transitions, resulting in a discontinuous and inefficient process. Furthermore, this scheme does not optimize for the high-speed water entry of the aerial power system. With a rigid connection, the fluid impact encountered by the propeller cannot be buffered, easily leading to damage to the power system and severely limiting the overall entry speed and structural reliability of the UAV. Patent application number 202411499209.7 discloses a marine exploration amphibious UAV that adds a buoyancy adjustment mechanism to the existing aerial quadcopter and underwater thruster. This buoyancy adjustment mechanism adjusts the air chamber volume by actively drawing in or expelling water, primarily used to assist the UAV in attitude adjustments on the water surface and slow underwater descent and ascent, or to achieve underwater hovering. However, its cross-medium transition requires first stabilizing on the water surface, failing to address the dynamic impact problem during the cross-medium process.

[0004] A buffer structure can be used to address the impact issues encountered by UAVs during high-speed water entry and exit. However, traditional mechanical buffer structures often employ rubber damping or spring supports, which have fixed damping characteristics and cannot be adjusted in real time according to the dynamic requirements of different media environments, easily leading to energy loss or response lag. During the rotor's entry and exit from the water, due to sudden changes in fluid load, the system is susceptible to overshoot and oscillation risks, adversely affecting flight stability and control accuracy. Summary of the Invention

[0005] To address the aforementioned technical issues, this application designs a cross-medium unmanned aerial vehicle (UAV) based on an active torque buffering device, which functions using an electro-controlled magnetorheological damping system. This cross-medium UAV actively controls the stiffness of its propulsion system to complete high-speed cross-medium tasks by adjusting the magnetic field strength of the coils within the torque buffering device, thereby driving a sudden viscosity change in the magnetorheological material. This design, through dynamic adjustment of the magnetic field, allows the propulsion system to switch bidirectionally between a high-stiffness state and an energy-dissipation state, ensuring the active absorption and release of the enormous torque impact caused by changes in propeller rotation state during high-speed cross-medium operations, thus guaranteeing structural safety. Furthermore, the modular design facilitates integration of the buffering device with the UAV frame and motors, possessing strong reliability and application value, and meeting the requirements of cross-medium operations.

[0006] This application adopts the following technical solution: A cross-medium unmanned aerial vehicle (UAV) based on an active torque buffering device improves its control robustness in complex fluid environments by adjusting the damping characteristics of the actuator to suppress transient load impacts at the medium transition interface. This UAV employs an integrated active torque buffering scheme, characterized by a simple system topology and low power consumption. It effectively reduces structural redundancy and added weight of the cross-medium platform, improving the overall load performance and energy efficiency. By adjusting the electromagnetic state within the active torque buffering device, the stiffness characteristics of the power system are dynamically altered using magnetorheological effects, achieving seamless power transition throughout the cross-medium process. Compared to configurations equipped with independent underwater propulsion units or buoyancy adjustment mechanisms, this scheme eliminates the need for mode adjustments or mechanical mode switching when the UAV traverses the water-air interface, ensuring continuous mission execution and dynamic response. Simultaneously, the active torque buffering mechanism effectively absorbs transient impact loads generated by sudden changes in the medium, protecting the drive motor and fuselage structure from damage, significantly enhancing the UAV's operational reliability and control robustness in complex fluid environments.

[0007] The cross-medium UAV based on an active torque buffer device includes a frame, a drive motor, a sealed control compartment, a connector, a propeller, and an active torque buffer device. The sealed control compartment is located at the center of the frame, and the active torque buffer device is located at the end of the frame. The propeller is fixed to the top of the drive motor, and the drive motor is mounted on the upper end of the active torque buffer device via the connector.

[0008] The active torque buffer device includes a rotor, an upper end cover, an upper rolling bearing, a sealing ring, a stator, a magnetorheological material, an electromagnetic coil, a lower rolling bearing, a shaft end retaining ring, and a lower end cover. The stator serves as the outer shell and is fixed to the end of the frame. The rotor is located inside the stator and is supported by the upper and lower rolling bearings, ensuring its smooth rotation relative to the stator. The connecting piece is fixed to the rotor and then fixedly connected to the drive motor. The upper and lower end covers are located at both ends of the stator, and together with the stator, they fix the upper and lower rolling bearings, thereby restricting their positions.

[0009] The rotor has a step and a shaft groove at its lower end. The step is fixed in position to the upper end of the lower rolling bearing, and the shaft groove is used to install a shaft end retaining ring. The shaft end retaining ring protrudes from the rotor surface and is fixed in position to the lower end of the lower rolling bearing. The rotor step, the lower rolling bearing, and the shaft end retaining ring together restrict the axial position of the rotor.

[0010] The stator has a groove on its inner wall. The electromagnetic coil is wound in the groove on the inner wall of the stator, and the electromagnetic coil is directly opposite the region where the magnetorheological material is located. The rotor is designed as a cylindrical structure with small diameters at both ends and a large diameter in the middle. The outer circumferential surface of the large diameter section of the rotor is coaxially opposite to the inner circumferential surface of the stator, forming an annular shear gap with a very small radial width between them, which is filled with magnetorheological material. The sealing ring is provided on the inner side (i.e., the side facing the magnetorheological material) of both the upper and lower rolling bearings to isolate the upper and lower rolling bearings from the magnetorheological material.

[0011] The working method of the above-mentioned cross-medium UAV based on the active torque buffer device is as follows: During aerial or underwater cruising, the active torque buffer operates at high stiffness. The UAV's sealed control cabin sends control signals to an electromagnetic coil, which then carries a corresponding current. This current generates a strong magnetic field, causing the magnetorheological material to thicken dramatically, transforming it into a high-strength semi-solid. This semi-solid magnetorheological material locks the rotor to the stator, creating a rigid connection between the drive motor and the active torque buffer to ensure rapid control response.

[0012] When the UAV is traveling at high speed across a medium, the active torque buffer device operates in a flexible buffer state. The UAV's sealed control cabin dynamically adjusts the current in the electromagnetic coils. The magnetorheological material reverts to a low-viscosity liquid state. When the torque load on the propeller contacts the cross-medium surface abruptly, the drive motor and rotor can rotate slightly relative to the stator, dissipating the impact energy as heat by shearing the low-viscosity magnetorheological material. This provides real-time response to the impact, protects the drive motor from damage, and improves cross-medium performance.

[0013] The beneficial effects of this invention are as follows: 1. Dynamic cross-medium UAV conversion scheme: Unlike the separate power system scheme, the cross-medium UAV based on the active torque buffer device does not require mechanical action switching or mode adjustment at the cross-medium interface. During the crossing process, the power system energy can be dissipated, realizing the continuity of the cross-medium process. This ensures the dynamic connection of the entire mission and the real-time continuity of power output, and is suitable for emergency search and rescue, rapid deployment and other scenarios.

[0014] 2. Integrated and Simplified Power System: This cross-medium UAV achieves a high degree of unification in water-air cross-medium propulsion through a single integrated buffer module of the power chain. Compared to a "separate power system" equipped with an independent underwater drive unit, or a "buoyancy adjustment mechanism" with a water pump and air chamber, this solution greatly simplifies the hardware topology and eliminates the additional weight caused by redundant mechanisms. This design optimizes the overall structural compactness while maintaining multi-medium adaptability.

[0015] 3. Cross-medium operation stability and structural reliability: By actively adjusting the torque characteristics of the drive end, this cross-medium UAV actively absorbs and unloads the transient load peaks caused by sudden changes in fluid density on the transmission chain while maintaining the steady state of system dynamics. This effectively prevents stress damage to the motor bearings and frame structure, fundamentally improving the UAV's operational life under harsh conditions. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall unmanned aerial vehicle (UAV) system. Figure 2 This is a schematic diagram of the unmanned aerial vehicle's power system. Figure 3 This is a schematic cross-sectional view of the active torque buffer device; Figure 4 This is a schematic diagram of the rotor structure of the torque buffer device; Reference numerals: 1-Sealed control chamber; 2-Propeller; 3-Drive motor; 4-Connector; 5-Active torque buffer device; 501-Rotor; 502-Upper end cover; 503-Upper rolling bearing; 504-Sealing ring; 505-Stator; 506-Magnetorheological material; 507-Electromagnetic coil; 508-Lower rolling bearing; 509-Shaft end retaining ring; 510-Lower end cover; 6-Frame. Detailed Implementation

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 As shown, this application discloses a cross-medium unmanned aerial vehicle (UAV) based on an active torque buffer device. The UAV's sealed control compartment 1 is installed at the center of the frame 6, and the active torque buffer device 5 is installed at the end of the frame 6.

[0019] like Figure 2 As shown, the drive motor 3 is mounted on the upper end of the active torque buffer device 5 via the connector 4, and the propeller 2 is fixed on the top of the drive motor 3.

[0020] like Figure 3 As shown, the active torque buffer device 5 includes a rotor 501, an upper end cover 502, an upper rolling bearing 503, a sealing ring 504, a stator 505, a magnetorheological material 506, an electromagnetic coil 507, a lower rolling bearing 508, a shaft end retaining ring 509, and a lower end cover 510. The stator 505 serves as the outer shell and is fixedly connected to the end of the frame 6. The rotor 501 is located inside the stator 505 and is supported by the upper rolling bearing 503 and the lower rolling bearing 508, ensuring that it can rotate smoothly relative to the stator 505. The connecting piece 4 is fixed to the rotor 501 and then fixedly connected to the drive motor 3. The upper end cover 502 and the lower end cover 510 are located at both ends of the stator 505, and together with the stator 505, they fix the upper rolling bearing 503 and the lower rolling bearing 508, thereby restricting the position of the upper rolling bearing 503 and the lower rolling bearing 508.

[0021] like Figure 4 As shown, the rotor 501 has a step and a shaft groove at its lower end. The step is fixed in position to the upper end of the lower rolling bearing 508, and the shaft groove is used to install a shaft end retaining ring 509. The shaft end retaining ring 509 protrudes from the surface of the rotor 501 and is fixed in position to the lower end of the lower rolling bearing 508. The rotor 501 step, the lower rolling bearing 508, and the shaft end retaining ring 509 together restrict the axial position of the rotor 501.

[0022] The electromagnetic coil 507 is wound in a groove on the inner wall of the stator 505, with the electromagnetic coil facing the region where the magnetorheological material is located. The rotor 501 is designed as a cylindrical structure with small diameters at both ends and a large diameter in the middle. The outer circumferential surface of the large diameter section of the rotor 501 is coaxially opposite to the inner circumferential surface of the stator 505, forming an annular shear gap with a very small radial width between them, which is filled with magnetorheological material 506. The sealing ring 504 is provided on the inner side (i.e., the side facing the magnetorheological material) of both the upper rolling bearing 503 and the lower rolling bearing 508 to isolate the upper rolling bearing 503 and the lower rolling bearing 508 from the magnetorheological material 506.

[0023] During aerial or underwater cruising, the active torque buffer device operates at high stiffness. The UAV's sealed control cabin 1 sends a control signal to the electromagnetic coil 507, causing it to receive a corresponding current. This current generates a strong magnetic field, causing the magnetorheological material 506 to increase in viscosity dramatically, transforming it into a high-strength semi-solid. This semi-solid magnetorheological material locks the rotor 501 onto the stator 505, creating a rigid connection between the drive motor 3 and the active torque buffer device 5 to ensure rapid control response.

[0024] When the UAV is traveling at high speed across a medium, the active torque buffer device is in a flexible buffer state. The UAV's sealed control cabin 1 dynamically adjusts the current of the electromagnetic coil 507. The magnetorheological material 506 returns to a low-viscosity liquid state. When the propeller 2 contacts the cross-medium surface and the torque load changes abruptly, the drive motor 3, together with the rotor 501, can rotate slightly relative to the stator 505. By shearing the low-viscosity magnetorheological material 506, the impact energy is dissipated into heat energy, thereby responding to the impact in real time, protecting the drive motor 3 from damage, and improving the cross-medium performance.

[0025] The embodiments described above are merely some preferred embodiments of the present invention, and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A cross-medium unmanned aerial vehicle (UAV) based on an active torque buffer device, characterized in that, The active torque buffer device is located at the end of the UAV frame; a drive motor is installed on the upper end of the active torque buffer device via a connector, and a propeller is fixed on the top of the drive motor. The active torque buffer device includes a rotor, an upper end cover, an upper rolling bearing, a stator, a magnetorheological material, an electromagnetic coil, a lower rolling bearing, a shaft end retaining ring, and a lower end cover. The stator serves as the outer shell and is fixedly connected to the end of the UAV frame. The rotor is located inside the stator and is supported by the upper and lower rolling bearings to ensure its smooth rotation relative to the stator. The connecting piece is fixed to the rotor and then fixedly connected to the drive motor. The upper and lower end covers are located at both ends of the stator and, together with the stator, fix the upper and lower rolling bearings, thereby limiting the position of the upper and lower rolling bearings. The magnetorheological material is disposed between the rotor and the stator; the electromagnetic coil is disposed inside the stator, directly opposite the region where the magnetorheological material is located; when current is passed through the electromagnetic coil, a magnetic field is generated, and the magnitude of the magnetic field is changed by changing the magnitude of the current, thereby changing the viscosity of the magnetorheological material; When the drone crosses the medium, the current in the control electromagnetic coil keeps the magnetorheological material in a low viscosity state, and the active torque buffer device is in a flexible buffer state. When the drone is cruising in the air or underwater, the current in the control electromagnetic coil keeps the magnetorheological material in a high-strength semi-solid state, and the active torque buffer device in a high-stiffness state.

2. The cross-medium UAV based on an active torque buffer device according to claim 1, characterized in that, The rotor has a step and a shaft groove at its lower end; the step is fixed in position to the upper end of the lower rolling bearing; a shaft end retaining ring is installed in the shaft groove, the shaft end retaining ring protrudes from the rotor surface and is fixed in position to the lower end of the lower rolling bearing; the rotor step, the lower rolling bearing, and the shaft end retaining ring together restrict the axial position of the rotor.

3. The cross-medium UAV based on an active torque buffer device according to claim 1, characterized in that, The inner wall of the stator is provided with a groove, and the electromagnetic coil is wound in the groove; the rotor is coaxially arranged with the stator, and an annular gap is formed between them, and the annular gap is filled with the magnetorheological material.

4. A cross-medium UAV based on an active torque buffer device according to claim 1, characterized in that, Both the upper and lower rolling bearings are provided with sealing rings on the side facing the magnetorheological material to isolate the upper and lower rolling bearings from the magnetorheological material.

5. A cross-medium UAV based on an active torque buffer device according to claim 1, characterized in that, The drone's frame is also equipped with a sealed control compartment, which is used to send control signals to the electromagnetic coil, thereby allowing a corresponding current to flow into the electromagnetic coil.

6. A cross-medium UAV based on an active torque buffer device according to claim 1, characterized in that, The active torque buffer device operates as follows: When the drone crosses the medium, the active torque buffer device is in a flexible buffer state; when the propeller contacts the cross-medium surface and the torque load changes suddenly, the drive motor and the rotor rotate slightly relative to the stator, dissipating the impact energy into heat energy by shearing the low-viscosity magnetorheological material, thus responding to the impact in real time. When the drone is cruising in the air or underwater, the active torque buffer device is in a high-rigidity state; the high-strength semi-solid magnetorheological material locks the rotor to the stator, making the drive motor and the active torque buffer device rigidly connected to ensure control response speed.

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