Foldable cross-media coaxial rotorcraft with paddles and control method thereof

Abstract

This invention provides a cross-medium coaxial dual-rotor UAV with foldable propellers and its control method. The UAV includes a main body module, a vector motor mount module, a coaxial propeller power module, a foldable propeller module, a waterproof sealing module, and electronic equipment. The cross-medium power system of this invention reduces the effective area of ​​the propeller by using foldable propellers, fundamentally reducing the impact of different working media on propeller efficiency, lowering power loss, and extending endurance. Secondly, a combined coaxial propeller power system is designed, reducing the number of actuators, eliminating complex gear structures, lowering the weight of the UAV, and improving its reliability. Finally, control code suitable for cross-medium coaxial dual-rotor UAVs is designed, realizing automatic motor speed control and propeller folding under different working media, making power distribution more rational in cross-medium missions.

Description

Technical Field

[0001] This invention relates to the fields of underwater propulsion technology and aviation technology, specifically to a cross-medium coaxial dual-rotor unmanned aerial vehicle with foldable propellers and its control method. Background Technology

[0002] In recent years, with the continuous development of UAV technology, scholars at home and abroad have become enthusiastic about the research of cross-medium UAVs. After a period of research and development, the research on amphibious UAVs and submarine-launched UAVs has become relatively mature. Because cross-medium aircraft combine airborne flight capabilities and underwater navigation capabilities, they have better maneuverability and stealth, thus possessing a wider operating range and the ability to acquire more airborne and underwater enemy and friendly information. However, cross-medium UAVs suffer from drawbacks such as high energy consumption and limited operating space, which can no longer meet the needs of people performing cross-medium operations in complex environments. Therefore, it is necessary to develop new types of cross-medium UAVs. Cross-medium UAVs can be classified into fixed-wing aircraft and rotary-wing aircraft according to their wing type. They can also be classified into amphibious UAVs, submarine-launched UAVs, and submersible UAVs according to their navigation methods in water bodies.

[0003] The defining characteristic of unmanned aerial vehicles (UAVs) is the presence of buoys or other buoyancy-providing devices on their underside, allowing them to anchor or glide on the water's surface. They can operate independently, with propellers or rotors providing lift or thrust for takeoff or gliding. For example, the Soviet LPL program featured a large buoy at the bottom, enabling the UAV to float on the water. A propeller generated thrust, while the fixed wings provided lift, allowing for takeoff, landing, and gliding on the water. Another example is the GULL36 developed by Warrior Sea & Air Technologies Ltd. in the UK. This high-wing configuration lacks buoyancy-providing devices at the bottom, but its cylindrical fuselage itself acts as a large buoy. The high-wing configuration allows the power unit to be positioned on the water's surface, providing thrust for takeoff, landing, and gliding. However, a summary and analysis of existing UAVs reveals that they cannot achieve true cross-medium navigation; at best, they can only float on the water's surface, and are not, in essence, fully cross-medium UAVs.

[0004] Submarine-launched unmanned aerial vehicles (UAVs) are characterized by their simple structure, relying solely on propellers or rotors to provide the necessary power for underwater and aerial operations. However, they cannot operate independently and generally need to be carried on a submarine, launched when required.

[0005] Therefore, they only possess single-use cross-medium capabilities and cannot navigate underwater for extended periods. For example, the Cormorant UAV developed by Lockheed Martin, after being launched from a submarine, relies on its own buoyancy to surface and then takes off again via its rotor, achieving a single cross-medium operation. However, since it lacks underwater mobility, it requires an underwater robot for retrieval, which impacts the submarine's stealth and safety. Another example is the Switchblade UAV proposed by the United States. The Switchblade uses a launch tube for catapult launch; upon launch, its folded wings unfold, and its motor-driven propellers begin propulsion. During missions, the launch tube is ejected, the launch device surfaces, and the launch command is executed—a land-based launch method. It also lacks underwater navigation capabilities. Analysis of existing submarine-launched UAVs reveals that while they can achieve single-use cross-medium flight, they suffer from drawbacks such as cumbersome retrieval, poor maneuverability, and limited stealth.

[0006] The defining characteristic of underwater drones is their ability to operate across multiple media simultaneously and independently. For fixed-wing underwater drones, propulsion in both the air and underwater relies on rotors, employing a combined propulsion system. This results in lighter weight and simpler structure, but because water resistance is far greater than air resistance, energy consumption is significant. Furthermore, the wings generate even more water resistance underwater, leading to even higher energy consumption. Therefore, fixed-wing underwater drones often employ complex variable-sweep configurations. For example, the Dipper drone developed by ETH Zurich uses a fixed-wing configuration. In the air, its wings deploy to provide lift, while underwater, the wing sweep angle is increased to reduce water resistance. However, this variable-sweep mechanism also contributes to the drone's weight and structural complexity. Some multi-rotor underwater drones possess both air and underwater propulsion systems. Air propulsion powers the drone during flight, while underwater propulsion powers it. While this balances energy consumption in the air and underwater, it significantly increases the drone's weight and structural complexity. For example, the Loon Copter uses four different propellers in air and underwater media. Its depth control system consists of a depth sensor and a variable-flow buoyancy device. During surfacing, the aircraft first floats on the surface and then takes off like a seaplane by adjusting the depth control system. During re-entry, the aircraft first lands and floats on the surface, then sinks by adjusting the depth control system. Because two separate power systems result in heavy weight and poor endurance, multi-rotor underwater drones often use a combined propulsion system, sharing a single power system for both air and water. This offers advantages such as light weight, simple structure, and high maneuverability, but it also results in significant water resistance for the rotors underwater and a heavy load on the motors. For example, the Naviator, jointly developed by Rutgers University and the Office of Naval Research, is a quadcopter underwater drone using a combined propulsion system. The quadcopter employs the same control strategy in both air and water, relying on increased throttle during surfacing to take off from underwater. However, this navigation method still results in high water resistance for the rotors underwater, thus exposing problems of energy loss and reduced endurance.

[0007] In summary, existing cross-medium aircraft mainly suffer from the following shortcomings that urgently need improvement:

[0008] When navigating underwater, the power efficiency is low, the energy consumption is high, and the endurance is poor.

[0009] The fuselage structure has poor impact resistance when crossing media;

[0010] Coaxial junction mechanisms are complex to design and have low safety and reliability.

[0011] The actuators are numerous, the mechanical structure is complex, the weight is large, and the flexibility and reliability are low. Summary of the Invention

[0012] To address the problems of existing technologies, this invention provides a cross-medium coaxial dual-rotor UAV with foldable propellers and its control method. This reduces the impact of different working media on propeller efficiency, lowers power loss, and extends endurance. It can be applied to mission scenarios such as maritime patrol, underwater reconnaissance, communication relay, water quality monitoring, marine resource exploration, biological observation, and hydro-meteorological measurement, and has significant meaning and value for the future.

[0013] This invention provides a cross-medium coaxial dual-rotor UAV with foldable propellers, characterized in that: it includes a main body module and a coaxial propeller power module, the main body module has a vector motor mount module and a foldable propeller module fixed inside, and the coaxial propeller power module is fixedly connected to the main body module through the vector motor mount module;

[0014] The vector motor mount module includes a motor mount, a universal joint, a reinforcing frame, a servo motor mounting component, a servo motor, and a pipe clamp. The reinforcing frame is fixedly connected to the main body module via the pipe clamp. The top of the reinforcing frame is connected to the motor mount via a universal joint, and the bottom is fixedly connected to the servo motor mounting component. The servo motor is connected to the servo motor mounting component. The servo motor is connected to the motor mount via a ball joint and controls the motor mount to perform pitch or roll movements.

[0015] The coaxial propeller power module includes a reverse-rotor motor stator, a reverse-rotor motor rotor, a forward-rotor motor stator, a forward-rotor motor rotor, a motor bracket, a reverse-rotor motor output shaft, a forward-rotor propeller, a reverse-rotor propeller, a forward-rotor motor rotor connector, a forward-rotor propeller fixing component, a reverse-rotor motor output shaft connector, a reverse-rotor propeller fixing component, a propeller clamp, and a set screw. The motor bracket is fixedly connected to the vector motor mount module. The reverse-rotor motor stator is connected to the lower part of the motor bracket via an interference fit, and the forward-rotor motor stator is connected to the upper part of the motor bracket via an interference fit. One end of the reverse-rotor motor output shaft passes through the forward-rotor motor stator, the forward-rotor motor rotor, and the reverse-rotor motor. The stator of the motor is fixed to the rotor of the reverse motor via set screws. The other end of the output shaft of the reverse motor is connected to the output shaft connector of the reverse motor via a propeller clamp. The output shaft connector of the reverse motor is connected to a reverse propeller fixing component via a cylindrical pin. The reverse propeller fixing component is connected to a reverse propeller. The rotor of the reverse motor drives the output shaft of the reverse motor to rotate, thereby driving the reverse propeller to rotate. The rotor of the forward motor is connected to a rotor connector of the forward motor. The rotor connector of the forward motor is fixed to a rotor connector of the forward motor via a cylindrical pin. The rotor connector of the forward motor is connected to the forward propeller. The rotation of the rotor of the forward motor drives the forward propeller to rotate.

[0016] The folding propeller module includes a push rod fixing component, a push rod, a tension stator, a tension rotor, a reverse tension rotor, a forward tension rotor, a tie rod structure, a Kevlar rope, a pipe clamp, a cylindrical pin, a spring pin, and a hook. The push rod fixing component is fixedly connected to the main body module via the pipe clamp, and the push rod is connected to the push rod fixing component via the cylindrical pin. One end of the tension stator is connected to the motor mount via the spring pin, and the other end is connected to the push rod via the Kevlar rope and the hook. The push rod's up-and-down movement drives the tension stator's up-and-down movement. The tension rotor is connected to the tension stator via a bearing, and the tension rotor rotates around the tension stator. The outer ring of the forward tension rotor... The forward-rotating stretching rotor is fixed to the reverse-rotating motor output shaft via an interference fit using a tie rod structure. The inner ring is fixed to the reverse-rotating motor output shaft via a clearance fit using a bearing. The forward-rotating stretching rotor rotates and moves up and down around the reverse-rotating motor output shaft. The forward-rotating stretching rotor is connected to the forward-rotating propeller fixing component via a tie rod structure. The up-and-down movement of the forward-rotating stretching rotor causes the forward-rotating propeller to fold. The reverse-rotating stretching rotor is connected to the forward-rotating stretching rotor via a deep groove ball bearing. The reverse-rotating stretching rotor rotates around the forward-rotating stretching rotor but cannot move relative to it. The reverse-rotating stretching rotor is connected to the reverse-rotating propeller fixing component via a tie rod structure. The up-and-down movement of the reverse-rotating stretching rotor causes the reverse-rotating propeller to fold.

[0017] Further improvements include a ball joint connecting rod in the vector motor mount module, which consists of a ball joint and a carbon rod. The two ends of the carbon rod are respectively connected to ball joints through interference fit, forming a ball joint connecting rod structure with ball joints at both ends. One end of the ball joint is connected to the motor mount, and the other end of the ball joint is connected to the rudder arm. The rudder arm is connected to the servo motor through a spline.

[0018] Further improvements include a pitch servo and a roll servo, with a 90° difference in installation angle between the pitch servo and the roll servo.

[0019] Further improvements include a tie rod structure for the folding propeller module comprising a tie rod head and a carbon rod, with tie rod heads connected to both ends of the carbon rod to form a tie rod structure with tie rod heads at both ends.

[0020] Further improvements include a streamlined fuselage structure consisting of a front fuselage beam, a rear fuselage beam, a left fuselage section, a right fuselage section, and a lower fuselage section, with landing gear connected to the bottom of the fuselage structure.

[0021] Further improvements include a waterproof sealing module inside the main body module, which houses electronic equipment. The waterproof sealing module comprises a sealed cavity consisting of a sealed chamber, a sealed cover, and a sealed bottom. The sealed chamber is fixed to the main body module via an interference fit. The sealed cover is movably connected to the sealed chamber and sealed by a sealing ring. The sealed bottom is fixedly connected to the sealed chamber and sealed by a sealing ring. The electronic equipment includes a flight controller, an electronic speed controller, a battery, a receiver, a power module, a step-down module, a Wi-Fi data transmission module, and a GPS positioning module. The flight controller automatically controls the stable flight of the aircraft. The electronic speed controller powers the brushless motors and adjusts their speed. The battery powers the entire aircraft's power and control systems. The receiver receives signals from the remote controller. The power module measures the battery voltage and powers the flight controller, electronic speed controller, and step-down module. The step-down module powers the servos. The Wi-Fi data transmission module communicates with the ground station and sends and receives mission commands. The GPS positioning module receives GPS satellite information and provides positioning and navigation for the aircraft.

[0022] The present invention also provides a control method for a cross-medium coaxial dual-rotor unmanned aerial vehicle with foldable propellers, including flight mode, underwater mode and cross-medium mode;

[0023] The control methods for drones in flight modes include forward and backward movement, ascent and descent, roll, and yaw. Forward and backward movement involves a pitch vector servo controlling the coaxial propeller motors to tilt forward and backward, driving the coaxial propeller power module to generate a longitudinal horizontal force, thus moving the aircraft forward and backward. Ascent and descent involves the coaxial propeller motors synchronously increasing and decreasing power to generate acceleration in the vertical direction, achieving ascent and descent. Roll is controlled by a roll vector servo controlling the coaxial propeller motors to tilt left and right, generating a roll torque that gradually tilts the fuselage to one side, achieving roll. Roll generates a lateral horizontal force, thus moving the aircraft laterally. Yaw is controlled by the differential increase and decrease of power between the forward and reverse motors in the coaxial propeller power module, generating a yaw torque, thus achieving yaw.

[0024] The underwater mode control methods for the UAV include pitch attitude changes, yaw attitude changes, roll motion control, forward motion control, and folding propeller motion. Pitch attitude changes refer to the pitch vector servo controlling the coaxial propeller motor to tilt up and down, driving the coaxial propeller power module to generate a longitudinal horizontal force, thus producing a pitch torque and causing the UAV to pitch. Yaw attitude changes refer to the yaw vector servo controlling the coaxial propeller motor to tilt left and right, driving the coaxial propeller power module to generate a lateral horizontal force, thus producing a yaw torque and causing the UAV to yaw. The roll motion control method involves the differential increase and decrease of power between the forward and reverse motors in the coaxial propeller power module to generate a roll torque and achieve roll motion. The forward motion control method involves the synchronous increase and decrease of power by the motors in the coaxial propeller power module, causing the UAV to accelerate or decelerate in the horizontal direction. Folding propeller motion refers to the push rod driving the propeller to fold or unfold, reducing the effective area of ​​the propeller and thus reducing the drag of the propeller rotation underwater.

[0025] The drone's cross-medium mode includes switching from flight mode to underwater mode and vice versa. The control method for switching from flight mode to underwater mode involves detecting whether a remote control's water-entry command is received in flight mode. When the command is received, the propellers begin to fold, and the motor speed automatically switches to low speed mode, at which point the drone enters the water. Once the drone is fully submerged, it switches to underwater mode, and its flight attitude changes from longitudinal to lateral, completing the cross-medium process. The control method for switching from underwater mode to flight mode involves the drone receiving a cross-medium command from the remote control, changing its flight attitude from lateral to longitudinal, and the propellers begin to unfold. The motors remain in low speed mode. Once the drone is fully out of the water, the motor speed automatically switches to high speed mode, completing the cross-medium process and entering flight mode.

[0026] Further improvements include an underwater motion mode with five actuators: two tilt servos, two propeller motors, and a push rod. The tilt servos change the direction of the motor thrust to change the navigation attitude, specifically pitch and yaw. The two propeller motors provide thrust for the UAV's underwater navigation, controlling its forward and roll movements. The push rod folds the propellers to reduce underwater drag. In the aerial flight mode, there are four actuators: two tilt servos and two propeller motors. Changing the direction of the propeller motor pull achieves changes in flight attitude.

[0027] The beneficial effects of this invention are as follows:

[0028] The drone's propellers feature a foldable design, combined with low Reynolds number propellers, which minimizes underwater drag while maintaining efficiency in the air. This fundamentally reduces the impact of different working media on propeller efficiency, lowers energy loss, and extends endurance.

[0029] The spacing between the two pairs of propellers in the coaxial system was optimized, reducing the starting interference of the upper propeller on the lower propeller, further improving the propeller's propulsion efficiency and extending the endurance.

[0030] The slender cylindrical fuselage design gives the drone stronger anti-interference and impact resistance, enabling it to quickly enter and exit water.

[0031] A combined coaxial propeller power system was designed, which reduced the number of actuators, simplified the mechanical structure and control algorithm, facilitated inspection and maintenance, reduced the weight of the UAV, and improved the safety and reliability of the UAV structure.

[0032] A motor suitable for coaxial propellers was designed, eliminating the need for a complex gear transmission mechanism and improving the reliability of the drone;

[0033] Code was designed to control the motor speed of the UAV under different working media, so that the power distribution of the UAV in cross-media missions is more reasonable.

[0034] Unmanned aerial vehicles (UAVs) can be used in various mission scenarios such as maritime patrol, underwater reconnaissance, communication relay, water quality monitoring, marine resource exploration, biological observation, and hydro-meteorological measurement, and will have important significance and value in the future. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a perspective view of the overall structural shape of the cross-medium coaxial dual-rotor UAV with foldable propellers of the present invention.

[0037] Figure 2 This is a front view of the overall structural shape of the cross-medium coaxial dual-rotor UAV with foldable propellers of the present invention;

[0038] Figure 3 These are the side and top views of the cross-medium coaxial dual-rotor UAV with foldable propellers of the present invention.

[0039] Figure 4This is a partial cross-sectional view of the front view of the cross-medium coaxial dual-rotor UAV with foldable propellers of the present invention.

[0040] Figure 5 This is a structural diagram of the main body module of the cross-medium coaxial dual-rotor UAV with foldable propellers according to the present invention;

[0041] Figure 6 This is a structural diagram of the vector motor mount module of the cross-medium coaxial dual-rotor UAV with foldable propellers of the present invention;

[0042] Figure 7 This is a structural diagram of the coaxial propeller power module of the cross-medium coaxial dual-rotor UAV with foldable propeller of the present invention;

[0043] Figure 8 This is a structural diagram of the folding propeller module of the cross-medium coaxial dual-rotor UAV with foldable propellers of the present invention;

[0044] Figure 9 This is a structural diagram of the waterproof sealing module of the cross-medium coaxial dual-rotor UAV with foldable propellers of the present invention;

[0045] Figure 10 This is a schematic diagram of the electronic equipment of the cross-medium coaxial dual-rotor UAV with foldable propellers of the present invention;

[0046] Figure 11 This is a schematic diagram of the cross-medium process of the cross-medium coaxial dual-rotor UAV with foldable propellers of the present invention.

[0047] In the attached diagram: 1. Main fuselage module; 2. Vector motor mount module; 3. Coaxial propeller power module; 4. Folding propeller module; 5. Waterproof sealing module; 6. Electronic equipment; 101. Right fuselage section; 102. Rear fuselage beam b; 103. M3 nut; 104. M3 screw; 105. Lower fuselage section; 106. Landing gear; 107. Rear fuselage beam a; 108. Left fuselage section; 109. Front fuselage beam a; 110. Front fuselage beam b; 201. Motor mount; 202. Universal joint; 203. Reinforced fixing frame; 204. 205. Pipe clamp; 206. Rudder arm; 207. Servo a; 208. Stud M2; 209. Screw M2; 210. Servo mounting bracket; 211. Servo b; 212. Ball joint; 213. Carbon rod; 214. Nut M2; 301. Reverse propeller; 302. First screw M4; 303. Reverse propeller mounting bracket; 304. Reverse motor output shaft connector; 305. Second screw M2; 306. Forward motor rotor connector; 307. Reverse motor output shaft; 308. Forward motor rotor; 309. Forward motor stator; 310. Third screw M3; 311. Set screw; 312. Reverse motor rotor; 313. Reverse motor stator; 314. Motor bracket; 315. Forward propeller; 316. Forward propeller fixing component; 317. First cylindrical pin; 318. Propeller clamp; 401. Pull rod head; 402. Second carbon rod; 403. Reverse tension rotor; 404. 6800V deep groove ball bearing; 405. MR63 ZZ bearing; 406. Forward tension rotor; 407. Bearing 50x62x6; 408. Tension rotor; 409. Pull... 410. Stator; 411. Spring pin; 412. Push rod; 413. Second cylindrical pin M3; 414. Push rod fixing part; 415. Second pipe clamp; 416. Second screw M2; 417. Kevlar rope; 418. Hook; 501. Third cylindrical pin M2; 502. Sealing box cover; 503. Sealing ring; 504. Sealing chamber; 505. Sealing box bottom; 506. Second nut M2; 601. Flight controller; 602. Step-down module; 603. WiFi data transmission module; 604. GPS positioning module; 605. Power module; 606. Electronic speed controller; 607. Receiver; 608. Battery. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0049] This invention provides a cross-medium coaxial dual-rotor unmanned aerial vehicle with foldable propellers, including a main body module 1, a vector motor mount module 2, a coaxial propeller power module 3, a foldable propeller module 4, a waterproof sealing module 5, and electronic equipment 6.

[0050] The main fuselage module 1 includes a front fuselage beam a109, a front fuselage beam b110, a rear fuselage beam a107, a rear fuselage beam b102, a left fuselage section 108, a right fuselage section 101, a lower fuselage section 105, landing gear 106, screws 104, nuts 103, etc. The front fuselage beam a109 is connected to the left fuselage section 108 by an interference fit, the front fuselage beam b110 is connected to the right fuselage section 101 by an interference fit, the rear fuselage beam a107 is connected to the left fuselage section 108 by an interference fit, the rear fuselage beam b102 is connected to the right fuselage section 101 by an interference fit, and the left fuselage section 108 and the right fuselage section 101 are connected by screws 104 and nuts 103. The screws 104 pass through screw holes in the left and right fuselage sections respectively, and are then fixed by nuts 103. The front fuselage beam a109, the front fuselage beam b110, the rear fuselage beam a107, and the rear fuselage beam b102 are connected to the lower fuselage section 105 via an interference fit. The lower fuselage section 105 and the left fuselage section 108 are connected by screws 104 and nuts 103, with the screws 104 passing through the screw holes of both sections. The lower fuselage section 105 and the right fuselage section 101 are also connected by screws 104 and nuts 103, with the screws 104 passing through the screw holes of both sections. This connection serves to secure the front fuselage beams a109, b110, a107, and b102. This assembly forms a complete streamlined fuselage.

[0051] The vector motor mount module 2 includes a motor mount 201, a universal joint 202, a reinforcing frame 203, a servo mount 209, servo a 206, servo b 210, a servo arm 205, a ball joint 211, a carbon rod 212, screws M2 208, studs M2 207, and a pipe clamp 204. The motor mount 201 is connected to the universal joint 202 by screws M2 208, which pass through the screw holes of both the motor mount and the universal joint. The universal joint 202 is connected to the reinforcing frame 203 by screws M2 208, which pass through the screw holes of both the universal joint 202 and the reinforcing frame 203. The reinforcing frame 203 is connected to the pipe clamp 204 by screws M2 208, which pass through the screw holes of both the reinforcing frame and the pipe clamp. The pipe clamp 204 is fixed to the front beam a, front beam b, rear beam a, and rear beam b of the fuselage via an interference fit, thereby fixing the reinforcing frame 203 to the main fuselage module. The motor mount 201 is connected to the ball joint 211 by screws M2 208, which pass through the screw holes of the motor mount and the ball joint respectively. The ball joint 211 is fixed to the carbon rod 212 via an interference fit, and the other side of the carbon rod is fixed to the ball joint 211 via an interference fit, forming a tie rod with ball joints at both ends. The ball joint 211 is connected to the servo arm 205 by screws M2 208, which pass through the screw holes of the servo arm and the ball joint respectively. The servo arm 205 is connected to the servo motor a206 via a spline. The servo motor a206 is connected to the servo motor mounting part 209 by screws M2 208. After installation, the rotation of the servo motor a can drive the motor mount to pitch. The installation method of the servo motor b210 is exactly the same as that of the servo motor a206, except that it is rotated 90° counterclockwise for installation, controlling the rolling movement of the motor mount. The servo motor mounting component 209 and the reinforcing mounting frame 203 are connected by the stud M2 207 and the screw M2 208. The servo motor mounting component 209 is screwed to the lower part of the stud M2 207, and the reinforcing mounting frame 203 is screwed to the upper part of the stud, thereby connecting the servo motor mounting component 209 and the reinforcing mounting frame 203 together. These parts are assembled together to form a vector motor mount module.

[0052] The coaxial propeller power module 3 includes a reverse-rotation motor stator 313, a reverse-rotation motor rotor 312, a forward-rotation motor stator 309, a forward-rotation motor rotor 308, a motor bracket 314, a reverse-rotation motor output shaft 307, a forward-rotation propeller 315, a reverse-rotation propeller 301, a forward-rotation motor rotor connector 306, a forward-rotation propeller fixing component 316, a reverse-rotation motor output shaft connector 304, a reverse-rotation propeller fixing component 303, a propeller clamp 318, a set screw 311, a second screw M2 305, a screw M3 310, a first screw M4 302, and a first cylindrical pin 317. The reverse-rotation motor stator 313 is connected to the motor bracket 314 by an interference fit, and the reverse-rotation motor stator 313 is connected below the motor bracket 314. The forward-rotation motor stator 309 is connected to the motor bracket 314 by an interference fit, and the forward-rotation motor stator 309 is connected above the motor bracket 314. The output shaft 307 of the reverse motor passes through the stator 309, rotor 308, and stator 313 of the forward motor, and is fixed to the rotor 312 of the reverse motor by the set screw 311, thus enabling the rotor to rotate and drive the output shaft of the reverse motor to rotate. The rotor connector 306 of the forward motor is connected to the rotor 308 of the forward motor by the second screw M2 305, which passes through the screw holes of both the rotor connector and the rotor. The propeller fixing member 316 of the forward motor is fixed to the rotor connector 306 by the first cylindrical pin 317, which passes through the cylindrical pin holes of both the propeller fixing member and the rotor connector of the forward motor by an interference fit. The forward-rotating propeller 315 and the forward-rotating propeller fixing member 316 are fixed by the first screw M4 302, which passes through the screw holes of both the forward-rotating propeller and the forward-rotating propeller fixing member, thus enabling the forward-rotating motor rotor to rotate and drive the forward-rotating propeller to rotate. The reverse-rotating motor output shaft 307 and the reverse-rotating motor output shaft connector 304 are fixed by the propeller clamp 318, thus enabling the reverse-rotating motor output shaft connector to rotate and drive the reverse-rotating motor output shaft connector to rotate. The reverse-rotating propeller fixing member 303 and the reverse-rotating motor output shaft connector 304 are fixed by the first cylindrical pin 317, which passes through the cylindrical pin holes on both the reverse-rotating propeller fixing member and the reverse-rotating motor output shaft connector through an interference fit. The reverse-rotating propeller 301 and the reverse-rotating propeller fixing member 303 are connected by the first screw M4 302, which passes through the screw holes of both the reverse-rotating propeller and the reverse-rotating propeller fixing member, thus enabling the reverse-rotating motor rotor to rotate and drive the reverse-rotating propeller to rotate. These parts are assembled together to form a coaxial propeller power module.The coaxial propeller power module is connected to the vector motor mount module via the motor bracket 314 and the third screw M3 310. The third screw M3 310 passes through the screw holes of the motor bracket and the vector motor mount module respectively for fixing.

[0053] The folding propeller module 4 includes a push rod fixing component 413, a push rod 411, a tension stator 409, a tension rotor 407, a 50x62x6 bearing 407, a 6800V deep groove ball bearing 404, an MR63.ZZ bearing 405, a reverse tension rotor 403, a forward tension rotor 406, a pull rod head 401, a second carbon rod 402, a Kevlar rope 416, a second pipe clamp 414, a second screw M2 415, a third cylindrical pin M2 418, a second cylindrical pin M3 412, a spring pin 410, and a hook 417. The push rod 411 and the push rod fixing component 413 are connected by the second cylindrical pin M3 412, which passes through the cylindrical pin holes of the push rod and the push rod fixing component and is fixed by interference fit. The push rod fixing member 413 and the second pipe clamp 414 are connected by the second screw M2 415, which passes through the screw holes of the push rod fixing member and the pipe clamp respectively. The second pipe clamp 414 is fixed to the front beam a, front beam b, rear beam a, and rear beam b of the machine body by an interference fit, thus fixing the push rod fixing member 413 and the push rod 411 to the machine body. The tension stator 409 is connected to the motor base 201 by the spring pin 410. The bottom of the spring pin 410 is connected to the motor base by an interference fit, and the head of the spring pin passes through the positioning groove of the tension stator and connects to the tension stator, thus fixing the tension stator to the motor base. The tensioning stator 409 and the push rod 411 are connected by the Kevlar rope 416 and the hook 417. One end of the Kevlar rope 416 is connected to the hook, and the hook hooks onto the hook hole at the lower end of the tensioning stator, so that one end of the Kevlar rope 416 is connected to the lower end of the tensioning stator. The other end of the Kevlar rope 416 passes around the round hole at the head of the push rod and is then glued with 502 glue, so that the Kevlar rope 416 is connected to the push rod, which plays the role of driving the tensioning stator to move up and down when the push rod moves up and down. The stretching rotor 407 and the stretching stator 409 are connected by the bearing 50x62x6 407. The outer ring of the bearing 50x62x6 407 is fixed to the stretching rotor by an interference fit, which prevents the bearing 50x62x6 407 from moving up and down relative to the stretching rotor 408. The inner ring of the bearing 50x62x6 407 is connected to the stretching stator by an interference fit, which prevents the bearing from moving up and down relative to the stretching stator. In this way, the stretching rotor 407 can rotate around the stretching stator 409, but cannot move horizontally.The forward-rotating stretching rotor 406 and the stretching rotor 408 are connected by the pull rod head 401, the second carbon rod 402, and the third cylindrical pin M2 418. The pull rod head 401 and the second carbon rod 402 are bonded together with 502 glue to form a pull rod. One end of the pull rod is connected to the forward-rotating stretching rotor through the third cylindrical pin M2 418. The third cylindrical pin M2 418 passes through the cylindrical pin holes of the pull rod head and the forward-rotating stretching rotor respectively for fixation. The other end of the pull rod is also connected to the stretching rotor through the cylindrical pin M2. The third cylindrical pin M2 418 passes through the cylindrical pin holes of the pull rod head and the stretching rotor respectively for fixation. In this way, the forward-rotating stretching rotor and the stretching rotor are fixed. The forward-rotating stretching rotor 406 is connected to the output shaft of the reverse-rotating motor via the MR63.ZZ bearing 405. The outer ring of the MR63.ZZ bearing 405 is fixed to the forward-rotating stretching rotor 406 by an interference fit, and the inner ring of the MR63.ZZ bearing 405 is fixed to the output shaft of the reverse-rotating motor by a clearance fit. This ensures that the forward-rotating stretching rotor can only rotate and move up and down around the output shaft of the reverse-rotating motor. The forward-rotating stretching rotor 406 and the forward-rotating propeller fixing component 316 are also connected by a tie rod composed of the tie rod head 401 and the second carbon rod 402. One end of the tie rod is connected to the forward-rotating stretching rotor through the third cylindrical pin M2 418. The third cylindrical pin M2 418 is fixed by passing through the cylindrical pin holes of the tie rod head and the forward-rotating stretching rotor respectively. The other end of the tie rod is connected to the forward-rotating propeller fixing component through the third cylindrical pin M2 418. The third cylindrical pin M2 418 is fixed by passing through the cylindrical pin holes of the tie rod head and the forward-rotating propeller fixing component respectively, which plays the role of driving the forward-rotating propeller to fold when the forward-rotating stretching rotor moves up and down. The reverse stretching rotor 403 and the forward stretching rotor 406 are connected by the 6800V deep groove ball bearing 404. The outer ring of the 6800V deep groove ball bearing 404 is fixed to the reverse stretching rotor by an interference fit, and the inner ring of the 6800V deep groove ball bearing 404 is fixed to the forward stretching rotor by an interference fit. This allows the reverse stretching rotor to rotate around the forward stretching rotor but not to move relative to it. The reverse stretching rotor 403 and the reverse propeller fixing component 303 are connected by a tie rod consisting of a tie rod head 401 and the second carbon rod 402. One end of the tie rod is connected to the reverse stretching rotor through a third cylindrical pin M2 418. The third cylindrical pin M2 418 passes through the cylindrical pin hole of the tie rod head and the reverse stretching rotor, respectively, and is fixed. The other end of the tie rod is connected to the reverse propeller fixing component through a third cylindrical pin M2 418. The third cylindrical pin M2 418 passes through the reverse propeller fixing component and is fixed to the tie rod head, which plays the role of the reverse stretching rotor moving up and down to drive the reverse propeller to fold.The aforementioned components are assembled to form a folding propeller module, which drives the push rod to move up and down, thereby driving the stretching stator to move up and down, which in turn drives the stretching rotor to move up and down, thereby driving the forward and reverse stretching rotors to move up and down, thus driving the reverse and forward propellers to fold.

[0054] The waterproof sealing module 5 includes a sealing chamber 504, a sealing cover 502, a sealing bottom 505, a third screw M2 501, a sealing ring 503, and a second nut M2 506. The sealing chamber 504 is fixed to the front beam a, front beam b, rear beam a, and rear beam b of the fuselage via an interference fit, thus securing the sealing chamber to the fuselage. The sealing cover 502 is connected to the sealing chamber 504 via the third screw M2 501 and the second nut M2 506. The third screw M2 501 passes through screw holes in both the sealing cover and the sealing chamber for fixation. The sealing ring 503 is sandwiched between the sealing cover and the sealing chamber, providing a waterproof seal. The sealed box bottom 505 and the sealed chamber 504 are connected by the third screw M2 501 and the second nut M2 506. The third screw M2 501 passes through the screw holes of the sealed box bottom and the sealed chamber respectively for fixing. The sealing ring 503 is sandwiched between the sealed chamber and the sealed box bottom, which plays a role in waterproof sealing. In this way, a complete waterproof sealing module is assembled.

[0055] The electronic equipment includes a flight controller 601, an electronic speed controller 606, a battery 608, a receiver 607, a power module 605, a step-down module 602, a Wi-Fi data transmission module 603, and a GPS positioning module 604. The flight controller 601 is used for automatically controlling the stable flight of the aircraft. The electronic speed controller 606 is used to power the brushless motor and adjust its speed. The battery 608 is used to power the entire aircraft's power system and control system. The receiver 605 is used to receive signals from the remote controller. The power module 605 is used to measure the battery voltage and power the flight controller, electronic speed controller, and step-down module. The step-down module 602 is used to power the servos. The Wi-Fi data transmission module 603 is used to communicate with the ground station and send and receive mission command information. The GPS positioning module 604 is used to receive GPS satellite information and provide positioning and navigation for the aircraft.

[0056] This invention also provides a control method for a cross-medium coaxial dual-rotor UAV with foldable propellers. The main features of the UAV described in this invention are its ability to navigate in both the air and underwater, and its capacity for multiple water entry and exit. Specifically, it can achieve rapid and stable underwater maneuvering, as well as stable flight in the air and rapid water entry and exit. In underwater mode, there are five actuators: two tilt servos, two propeller motors, and one push rod. The main function of the tilt servos is to change the direction of the motor thrust to change the flight attitude, specifically pitch and yaw. The main function of the two propeller motors is to provide thrust for the UAV's underwater navigation, controlling its forward and roll movements. The main function of the push rod is to fold the propellers to reduce underwater drag. In aerial flight mode, there are four actuators: two tilt servos and two propeller motors. Changing the direction of the propeller motor thrust achieves changes in flight attitude, specifically pitch, yaw, and roll.

[0057] In flight mode, the control method for forward and backward movement of the UAV involves the pitch vector servo controlling the coaxial propeller motors to tilt forward and backward, driving the coaxial propeller power module to generate a longitudinal horizontal force, thus moving the aircraft forward and backward. The control method for altitude movement involves the coaxial propeller motors synchronously increasing and decreasing power, causing the aircraft to accelerate in the vertical direction, thereby achieving altitude movement. The control method for roll movement involves the roll vector servo controlling the coaxial propeller motors to tilt left and right, generating a roll torque, causing the fuselage to gradually tilt to one side, achieving roll movement. Roll movement generates a lateral horizontal force, thus driving the aircraft to move laterally. The control method for yaw movement involves the forward and reverse motors in the coaxial propeller power module differentially increasing and decreasing power, generating a yaw torque, thereby achieving yaw movement.

[0058] In underwater mode, the pitch attitude change refers to the pitch vector servo controlling the coaxial propeller motor to tilt up and down, driving the coaxial propeller power module to generate a longitudinal horizontal force, thereby generating a pitch torque and causing the drone to pitch. The yaw attitude change refers to the yaw vector servo controlling the coaxial propeller motor to tilt left and right, driving the coaxial propeller power module to generate a lateral horizontal force, thereby generating a yaw torque and causing the drone to yaw. The roll motion control method refers to the differential increase and decrease of power between the forward and reverse motors in the coaxial propeller power module to generate a roll torque and thus achieve roll motion. The forward motion control method refers to the synchronous increase and decrease of power by the motors in the coaxial propeller power module, causing the drone to accelerate or decelerate in the horizontal direction. The folding propeller motion refers to the push rod driving the propeller to fold or unfold, reducing the effective area of ​​the propeller and thus reducing the resistance of the propeller rotation underwater.

[0059] In cross-media mode, the drone can switch between flight mode and underwater mode, and vice versa. The control method for switching from flight mode to underwater mode involves detecting whether a water entry command is received from the remote controller while in flight mode. When the command is received, the propellers begin to fold, and the motor speed automatically switches to low speed mode, at which point the drone enters the water. Once the drone is fully submerged, it switches to underwater mode, and its flight attitude changes from longitudinal to lateral, completing the cross-media process. The control method for switching from underwater mode to flight mode involves the drone receiving a cross-media command from the remote controller, changing its flight attitude from lateral to longitudinal, and the propellers begin to deploy. The motors remain in low speed mode. Once the drone is fully out of the water, the motor speed automatically switches to high speed mode, completing the cross-media process and entering flight mode.

[0060] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. In particular, for the device embodiments, the above descriptions are merely preferred embodiments of the present invention. Since they are fundamentally similar to the method embodiments, the descriptions are relatively simple, and relevant parts can be referred to the descriptions of the method embodiments. The above descriptions are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention, without departing from the principle of the present invention, should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A cross-medium coaxial dual-rotor unmanned aerial vehicle with foldable propellers, characterized in that: It includes a main body module and a coaxial propeller power module. The main body module contains a vector motor mount module and a folding propeller module. The coaxial propeller power module is fixedly connected to the main body module through the vector motor mount module. The vector motor mount module includes a motor mount, a universal joint, a reinforcing frame, a servo motor mounting component, a servo motor, and a pipe clamp. The reinforcing frame is fixedly connected to the main body module via the pipe clamp. The top of the reinforcing frame is connected to the motor mount via a universal joint, and the bottom is fixedly connected to the servo motor mounting component. The servo motor is connected to the servo motor mounting component. The servo motor is connected to the motor mount via a ball joint and controls the motor mount to perform pitch or roll movements. The coaxial propeller power module includes a reverse-rotor motor stator, a reverse-rotor motor rotor, a forward-rotor motor stator, a forward-rotor motor rotor, a motor bracket, a reverse-rotor motor output shaft, a forward-rotor propeller, a reverse-rotor propeller, a forward-rotor motor rotor connector, a forward-rotor propeller fixing component, a reverse-rotor motor output shaft connector, a reverse-rotor propeller fixing component, a propeller clamp, and a set screw. The motor bracket is fixedly connected to the vector motor mount module. The reverse-rotor motor stator is connected to the lower part of the motor bracket via an interference fit, and the forward-rotor motor stator is connected to the upper part of the motor bracket via an interference fit. One end of the reverse-rotor motor output shaft passes through the forward-rotor motor stator, the forward-rotor motor rotor, and the reverse-rotor motor. The stator of the motor is fixed to the rotor of the reverse motor via set screws. The other end of the output shaft of the reverse motor is connected to the output shaft connector of the reverse motor via a propeller clamp. The output shaft connector of the reverse motor is connected to a reverse propeller fixing component via a cylindrical pin. The reverse propeller fixing component is connected to a reverse propeller. The rotor of the reverse motor drives the output shaft of the reverse motor to rotate, thereby driving the reverse propeller to rotate. The rotor of the forward motor is connected to a rotor connector of the forward motor. The rotor connector of the forward motor is fixed to a rotor connector of the forward motor via a cylindrical pin. The rotor connector of the forward motor is connected to the forward propeller. The rotation of the rotor of the forward motor drives the forward propeller to rotate. The folding propeller module includes a push rod fixing component, a push rod, a tension stator, a tension rotor, a reverse tension rotor, a forward tension rotor, a tie rod structure, a Kevlar rope, a pipe clamp, a cylindrical pin, a spring pin, and a hook. The push rod fixing component is fixedly connected to the main body module via the pipe clamp, and the push rod is connected to the push rod fixing component via the cylindrical pin. One end of the tension stator is connected to the motor mount via the spring pin, and the other end is connected to the push rod via the Kevlar rope and the hook. The push rod's up-and-down movement drives the tension stator's up-and-down movement. The tension rotor is connected to the tension stator via a bearing, and the tension rotor rotates around the tension stator. The outer ring of the forward tension rotor... The forward-rotating stretching rotor is fixed to the reverse-rotating motor output shaft via an interference fit using a tie rod structure. The inner ring is fixed to the reverse-rotating motor output shaft via a clearance fit using a bearing. The forward-rotating stretching rotor rotates and moves up and down around the reverse-rotating motor output shaft. The forward-rotating stretching rotor is connected to the forward-rotating propeller fixing component via a tie rod structure. The up-and-down movement of the forward-rotating stretching rotor causes the forward-rotating propeller to fold. The reverse-rotating stretching rotor is connected to the forward-rotating stretching rotor via a deep groove ball bearing. The reverse-rotating stretching rotor rotates around the forward-rotating stretching rotor but cannot move relative to it. The reverse-rotating stretching rotor is connected to the reverse-rotating propeller fixing component via a tie rod structure. The up-and-down movement of the reverse-rotating stretching rotor causes the reverse-rotating propeller to fold.

2. The cross-medium coaxial dual-rotor UAV with foldable propellers according to claim 1, characterized in that: The ball joint connecting rod in the vector motor mount module includes a ball joint and a carbon rod. The two ends of the carbon rod are respectively connected to ball joints by interference fit, forming a ball joint connecting rod structure with ball joints at both ends. The ball joint at one end is connected to the motor mount, and the ball joint at the other end is connected to the rudder arm. The rudder arm is connected to the servo motor by spline.

3. The cross-medium coaxial dual-rotor UAV with foldable propellers according to claim 1 or 2, characterized in that: The servo motors include a pitch servo motor and a roll servo motor, with a 90° difference in installation angle between the pitch servo motor and the roll servo motor.

4. The cross-medium coaxial dual-rotor UAV with foldable propellers according to claim 1, characterized in that: The pull rod structure of the folding propeller module includes a pull rod head and a carbon rod, with pull rod heads connected to both ends of the carbon rod to form a pull rod structure with pull rod heads at both ends.

5. The cross-medium coaxial dual-rotor UAV with foldable propellers according to claim 1, characterized in that: The main fuselage module includes a streamlined fuselage structure consisting of a front fuselage beam, a rear fuselage beam, a left fuselage section, a right fuselage section, and a lower fuselage section, with landing gear connected to the bottom of the fuselage structure.

6. The cross-medium coaxial dual-rotor UAV with foldable propellers according to claim 1, characterized in that: The main body module is equipped with a waterproof sealing module, and electronic devices are placed inside the waterproof sealing module.

7. The cross-medium coaxial dual-rotor UAV with foldable propellers according to claim 6, characterized in that: The waterproof sealing module includes a sealed cavity consisting of a sealing chamber, a sealing cover, and a sealing bottom. The sealing chamber is fixed to the main body module by an interference fit. The sealing cover is movably connected to the sealing chamber and sealed by a sealing ring. The sealing bottom is fixedly connected to the sealing chamber and sealed by a sealing ring.

8. The cross-medium coaxial dual-rotor UAV with foldable propellers according to claim 6 or 7, characterized in that: The electronic equipment includes a flight controller, an electronic speed controller, a battery, a receiver, a power module, a step-down module, a Wi-Fi data transmission module, and a GPS positioning module. The flight controller is used to automatically control the stable flight of the aircraft. The electronic speed controller is used to power the brushless motor and adjust its speed. The battery is used to power the power system and control system of the entire aircraft. The receiver is used to receive signals from the remote controller. The power module is used to measure the battery voltage and power the flight controller, electronic speed controller, and step-down module. The step-down module is used to power the servos. The Wi-Fi data transmission module is used to communicate with the ground station and send and receive mission command information. The GPS positioning module is used to receive GPS satellite information and to locate and navigate the aircraft.

9. A control method for a cross-medium coaxial dual-rotor unmanned aerial vehicle with foldable propellers as described in any one of claims 1-8, characterized in that: Includes flight mode, underwater mode, and cross-medium mode; The control methods for drones in flight modes include forward and backward movement, as well as rise and fall, roll, and yaw. The control methods for forward and backward movement are as follows: The pitch vector servo controls the coaxial propeller motors to tilt forward and backward, driving the coaxial propeller power module to generate a longitudinal horizontal force, thus moving the aircraft forward and backward. The control method for elevator movement is as follows: The coaxial propeller motors synchronously increase or decrease power, causing the aircraft to accelerate in the vertical direction, thereby achieving elevator movement. The control method for roll movement is as follows: The roll vector servo controls the coaxial propeller motors to tilt left and right, generating a roll torque, causing the fuselage to gradually tilt to one side, thus achieving roll movement. Roll movement generates a lateral horizontal force, thereby driving the aircraft to move laterally. The control method for yaw movement is as follows: The forward and reverse motors in the coaxial propeller power module differentially increase or decrease power, generating a yaw torque, thereby achieving yaw movement. The underwater mode control methods for the UAV include pitch attitude changes, yaw attitude changes, roll motion control, forward motion control, and folding propeller motion. Pitch attitude changes refer to the pitch vector servo controlling the coaxial propeller motor to tilt up and down, driving the coaxial propeller power module to generate a longitudinal horizontal force, thus producing a pitch torque and causing the UAV to pitch. Yaw attitude changes refer to the yaw vector servo controlling the coaxial propeller motor to tilt left and right, driving the coaxial propeller power module to generate a lateral horizontal force, thus producing a yaw torque and causing the UAV to yaw. The roll motion control method involves the differential increase and decrease of power between the forward and reverse motors in the coaxial propeller power module to generate a roll torque and achieve roll motion. The forward motion control method involves the synchronous increase and decrease of power by the motors in the coaxial propeller power module, causing the UAV to accelerate or decelerate in the horizontal direction. Folding propeller motion refers to the push rod driving the propeller to fold or unfold, reducing the effective area of ​​the propeller and thus reducing the drag of the propeller rotation underwater. The drone's cross-medium mode includes switching from flight mode to underwater mode and vice versa. The control method for switching from flight mode to underwater mode involves detecting whether a remote control's water-entry command is received in flight mode. When the command is received, the propellers begin to fold, and the motor speed automatically switches to low speed mode, at which point the drone enters the water. Once the drone is fully submerged, it switches to underwater mode, and its flight attitude changes from longitudinal to lateral, completing the cross-medium process. The control method for switching from underwater mode to flight mode involves the drone receiving a cross-medium command from the remote control, changing its flight attitude from lateral to longitudinal, and the propellers begin to unfold. The motors remain in low speed mode. Once the drone is fully out of the water, the motor speed automatically switches to high speed mode, completing the cross-medium process and entering flight mode.

10. The control method for a cross-medium coaxial dual-rotor UAV with foldable propellers according to claim 9, characterized in that, In the underwater mode, there are five actuators: two tilt servos, two propeller motors, and one push rod. The tilt servos change the direction of the motor thrust to change the navigation attitude, specifically pitch and yaw. The two propeller motors provide thrust for the UAV's underwater navigation, controlling its forward and roll movements. The push rod folds the propellers to reduce underwater drag. In the flight mode, there are four actuators: two tilt servos and two propeller motors. Changing the direction of the propeller motor pull changes the flight attitude.

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