Coaxial dual-rotor unmanned aerial vehicle and water access control method thereof

Abstract

The invention belongs to the technical field of dual-rotor unmanned aerial vehicles, and discloses a coaxial dual-rotor unmanned aerial vehicle and a water access control method thereof. The coaxial dual-rotor unmanned aerial vehicle comprises a structural platform, a power system, an upper rotor, a lower rotor and a solar power generation system, the solar power generation system comprises a solar thin film battery, a collector ring electric energy transmission device, a controller, an illumination sensor and a storage battery; wherein the illumination sensor is used for acquiring the illumination intensity of sunlight and inputting the illumination intensity into the controller; the solar thin-film batteries are fixedly arranged on the upper surfaces of the blades of the upper rotor wing and the lower rotor wing, the solar thin-film batteries are connected with the collector ring electric energy transmission device through connecting wires, and the connecting wires are led out from the roots of the blades; one side of the controller is connected with the collector ring electric energy transmission device, and the other side of the controller is connected with the storage battery; the storage battery is used for supplying power to the power system. According to the technical scheme, the long-endurance flight requirement of the coaxial dual-rotor unmanned aerial vehicle can be effectively met.

Description

Technical Field

[0001] The invention belongs to the technical field of dual-rotor UAVs, and in particular relates to a coaxial dual-rotor UAV and a water entry and exit control method thereof. Background Art

[0002] Coaxial twin-rotor UAVs refer to helicopters with upper and lower rotors on the same rotor shaft. They have the advantages of compact structure, strong maneuverability, and high hovering efficiency. They are widely used in emergency rescue, power inspection, maritime reconnaissance, etc. In recent years, as the application of UAVs continues to be explored and the application scenarios continue to expand, the market demand for long-flight, multi-functional and miniaturized UAVs has become more and more urgent.

[0003] At present, in view of the application requirements of long flight time, drones usually use hydrogen fuel cells, but hydrogen fuel cells have the characteristic of large volume density, which limits the miniaturization development of drones; further, NASA (National Aeronautics and Space Administration) proposed a "Ingenuity" Mars coaxial drone, which uses solar cells to power the drone to meet the long flight time, but the solar cell sails and rotor blades of this configuration of drone are separated and independent from each other. The solar cell sails block the rotor blades, affecting the upper dynamic inflow of the rotor blades located below, greatly reducing the aerodynamic pull of the rotor, and thus inhibiting the overall performance of the drone; in summary, it is urgent to develop a new type of coaxial twin-rotor drone. Summary of the invention

[0004] The purpose of the present invention is to provide a coaxial twin-rotor UAV and a water entry and exit control method thereof to solve one or more of the above-mentioned technical problems. The present invention specifically proposes a technical solution combining rotor blades with solar thin-film cells, which can effectively support the long-flight requirements of the coaxial twin-rotor UAV without increasing the volume of the coaxial twin-rotor UAV or weakening the overall performance of the coaxial twin-rotor UAV.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a coaxial dual-rotor UAV, comprising: a structural platform, a power system, an upper rotor, a lower rotor and a solar power generation system; wherein: The power system is fixedly arranged on the structural platform; the upper rotor and the lower rotor are arranged on the structural platform through the same rotor shaft; a transmission component is arranged between the power system and the upper rotor and the lower rotor; The upper rotor and the lower rotor both include blades and a hub, the blades are mounted on the hub, and the hub is used to be arranged at the center of the rotor to support the blades to rotate and change pitch; wherein the directions of the rotational movements of the upper rotor and the lower rotor are opposite; the rotation speed of the upper rotor is adjustable, and the rotation speed of the lower rotor is adjustable and can change the total pitch and cyclic pitch; The solar power generation system is installed on the structural platform, and the solar power generation system includes a solar thin-film battery, a collector ring power transmission device, a controller, a light sensor and a battery; wherein the light sensor is used to obtain the light intensity of sunlight and input it into the controller; the solar thin-film battery is fixedly arranged on the upper surface of the blades of the upper rotor and the lower rotor, and the solar thin-film battery is connected to the collector ring power transmission device through a connecting line, and the connecting line is led out from the root of the blade; one side of the controller is connected to the collector ring power transmission device, and the other side is connected to the battery, which is used to control the opening and closing of the solar thin-film battery according to the light intensity; the battery is used to supply power to the power system.

[0006] A further improvement of the coaxial twin-rotor UAV of the present invention is that: The power system includes a motor system and a steering gear system; Among them, the motor system includes a first motor and a second motor respectively used to provide rotational power to the upper rotor and the lower rotor; the servo system is used to adjust the thrust direction of the rotor discs of the upper rotor and the lower rotor.

[0007] A further improvement of the coaxial twin-rotor UAV of the present invention is that: The slip ring power transmission device is installed at the hub center of the upper rotor and the lower rotor; The collector ring power transmission device comprises an outer collector ring, an inner collector ring and a cable assembly.

[0008] A further improvement of the coaxial twin-rotor UAV of the present invention is that: In the controller, when the sunlight intensity is greater than or equal to 200 W / m² to 300 W / m² and the battery energy is not full, the solar thin-film battery is turned on to charge the battery; otherwise, the solar thin-film battery is turned off.

[0009] A further improvement of the coaxial twin-rotor UAV of the present invention is that: The upper surface of the solar thin-film cell is provided with a transparent protective layer.

[0010] A further improvement of the coaxial dual-rotor UAV of the present invention is that it also includes: A vibration energy collection device is installed on the structural platform and is used to convert the vibration energy of water into electrical energy and store it in a battery when the coaxial twin-rotor UAV is in water.

[0011] A further improvement of the coaxial dual-rotor UAV of the present invention is that it also includes: An offshore floating system is installed on the structural platform and is used to realize the floating or diving of the coaxial twin-rotor UAV when the coaxial twin-rotor UAV is in water.

[0012] A second aspect of the present invention provides a method for controlling entry and exit of a coaxial dual-rotor UAV, comprising: When entering the water from the air, the coaxial twin-rotor drone descends obliquely at a first preset angle when it is above the preset height above the water surface; after reaching the preset height above the water surface, the coaxial twin-rotor drone descends vertically and continuously reduces the rotation speeds of the upper rotor and the lower rotor; after touching the water surface, the rotation speed of the upper rotor drops to zero, and the lower rotor rotates at a first preset constant low speed; When entering the air from the water, the lower rotor of the coaxial twin-rotor UAV adopts a second preset constant low speed and realizes upward movement by controlling the variable collective pitch and cyclic pitch; when reaching the preset underwater depth, the upper rotor of the coaxial twin-rotor UAV begins to rotate and gradually increases the speed, and the lower rotor also gradually increases the speed, and breaks through the water obliquely at a second preset angle through the variable collective pitch and cyclic pitch of the lower rotor; after breaking through the water, the coaxial twin-rotor UAV flies obliquely to a certain height, and the upper rotor and the lower rotor respectively balance the torque at a constant high speed, and maintains posture stability through the variable speed of the upper rotor and the variable collective pitch and cyclic pitch of the lower rotor.

[0013] A further improvement of the water inlet and outlet control method of the present invention is that the value range of the first preset angle is 30° to 60°.

[0014] A further improvement of the water inlet and outlet control method of the present invention is that the value range of the second preset angle is 15° to 30°.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a coaxial twin-rotor UAV, which describes a scheme of conformal integration of rotor blades and solar thin-film cells, aiming to achieve ultra-long flight time capability, while ensuring that its comprehensive performance is maintained without increasing the overall volume of the UAV. The core of the technical solution of the present invention is to cleverly integrate the rotor blades and solar thin-film cells into a conformal structure. This conformal structure not only undertakes the key function of generating lift, but also innovatively integrates the power generation function, achieving dual optimization of structure and function; further specifically explanatory, the conformal structure enables the rotor blades to effectively cut the air during rotation to generate the lift required to lift the UAV, and the solar thin-film cells covered on the surface can capture sunlight and convert it into electrical energy to supply the UAV system, thereby significantly extending the flight time. This innovation avoids the problems of volume increase and performance drag that may be caused by traditional external solar panels, improves energy utilization efficiency, and ensures that the maneuverability and stability of the UAV are not affected.

[0016] The impact effect encountered by sea-air cross-domain aircraft when entering and exiting water not only significantly weakens the overall energy reserve of the aircraft, resulting in a double decrease in navigation speed and flight efficiency, but also poses a severe challenge to structural integrity; this impact, at the least, slows down the flight speed, and at the worst, directly causes irreversible damage to the key mechanical and electrical components of the drone, such as the rupture of the conformal structure of the blades and solar thin-film cells, which seriously affects the stable operation and mission execution capabilities of the aircraft. The water entry and exit method disclosed in the present invention can not only effectively buffer the impact energy generated by the drone during the water entry and exit process, significantly reduce the physical damage caused thereby, but also greatly improve the adaptability and practicality of the drone in different operating environments. Specifically, the method of the present invention is applied to a coaxial twin-rotor drone, and through a carefully designed control strategy, a unique operating mode of the drone entering the water steadily at a vertical angle and exiting the water efficiently at an oblique angle is realized. Compared with the traditional method, this innovative way of entering and exiting the water can greatly reduce the energy loss of the drone when crossing the water-land interface, and at the same time effectively reduce the potential damage to the drone body, especially its key components, caused by the impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below; obviously, the drawings described below are some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 1 is a schematic structural diagram of a coaxial twin-rotor UAV in an embodiment of the present invention; Figure 2 yes Figure 1A schematic top view of the illustrated embodiment; The explanations of the reference numerals in the figures are as follows: 1. Upper rotor; 2. Lower rotor; 3. Controller; 4. Battery; 5. Structural platform; 6. Light sensor; 7. Collector ring power transmission device; 8. Solar thin-film battery; 9. Connecting wire; 10. Collector outer ring. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments and technical solutions are only part of the embodiments of the present invention, not all of the embodiments.

[0020] All other embodiments obtained by those of ordinary skill in the art without creative work based on the technical solutions disclosed in the embodiments of the present invention belong to the scope of protection of the present invention. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device including a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0021] See also Figure 1 and Figure 2 , an embodiment of the present invention provides a coaxial dual-rotor UAV, which specifically includes: a structural platform 5, a power system, an upper rotor 1, a lower rotor 2 and a solar power generation system; The power system is fixedly arranged on the structural platform 5, and the upper rotor 1 and the lower rotor 2 are arranged on the structural platform 5 through the same rotor shaft; a transmission component is arranged between the power system and the upper rotor 1 and the lower rotor 2, and the transmission component is used to transmit the motor torque and output power in the power system; the upper rotor 1 and the lower rotor 2 both include blades and a hub, and the blades are mounted on the hub, and the hub is used to be arranged at the center of the rotor to support the blades to rotate and change pitch; The solar power generation system is installed on the structural platform 5, and the solar power generation system includes a solar thin film battery 8, a collector ring power transmission device 7, a controller 3, a light sensor 6 and a battery 4; wherein the light sensor 6 is used to obtain the light intensity of sunlight and input it into the controller 3; the solar thin film battery 8 is fixedly arranged on the upper surface of the blades of the upper rotor 1 and the lower rotor 2 to convert solar energy into electrical energy; the solar thin film battery 8 is connected to the collector ring power transmission device 7 through a connecting line 9, and the connecting line 9 is led out from the root of the blade; one side of the controller 3 is connected to the collector ring power transmission device 7, and the other side is connected to the battery 4 to regulate the current or voltage generated by the solar thin film battery 8 and stably charge the battery 4; one side of the battery 4 is used to receive power from the solar thin film battery 8 and stably charge it, and the other side is connected to the power system and airborne equipment to shunt and supply power to the power system and airborne equipment.

[0022] The technical solution provided by the embodiment of the present invention is specifically a technical solution of rotor blades conforming to solar thin film cells, which can support the coaxial twin-rotor UAV to fly for a long flight time without increasing the volume of the UAV and weakening the overall performance of the UAV; wherein, the conformal structure of the rotor blades and the solar thin film cells is both a lift component of the UAV and a power generation component of the UAV. The technical solution of the embodiment of the present invention can improve the application effect of such aircraft, expand its application scenarios, and improve its practicality. The technical solution of the embodiment of the present invention can not only promote the in-depth application of coaxial twin-rotor UAVs in the fields of remote monitoring, environmental monitoring, disaster assessment, etc., but also because of its unique energy self-sufficiency characteristics, it provides the possibility of exploring operations in longer distances and more complex environments, greatly expanding the application scenarios of UAVs, and improving their practical value and market competitiveness. In summary, the embodiment of the present invention brings revolutionary performance improvement to coaxial twin-rotor UAVs through the conformal design of rotor blades and solar thin film cells, which not only promotes the progress of long-flight flight technology, but also opens up a new path for the sustainable development of the UAV industry.

[0023] In the technical solution of the embodiment of the present invention, the upper rotor 1 and the lower rotor 2 rotate in opposite directions, and the lift is generated by the rotational motion and the surrounding air; wherein, the speed of the upper rotor 1 is adjustable, and the speed of the lower rotor 2 is adjustable and can change the total pitch and cyclic pitch. Explanatory, the existing coaxial twin-rotor UAV adopts two rotor systems, and the upper rotor and the lower rotor rotate in opposite directions. When the upper rotor and the lower rotor perform cyclic pitch change, there is a problem that the upper blade and the lower blade are easy to collide and break. When the above problem is solved by increasing the spacing between the upper rotor and the lower rotor, the outer size of the UAV will increase, the rigidity of the rotating shaft will decrease, and the cross-sectional size needs to be increased to compensate for the defects of the rigidity design of the rotor shaft; the technical solution disclosed in the embodiment of the present invention adopts the technical means of combining upper speed change with lower pitch change, which can effectively solve the problem of collision and breakage of the upper and lower rotors without introducing new defects.

[0024] In one embodiment of the present invention, the power system includes a motor system and a servo system; wherein the motor system includes a first motor and a second motor for providing rotational power to the upper rotor 1 and the lower rotor 2 respectively; the servo system is used to adjust the thrust direction of the rotor discs of the upper rotor 1 and the lower rotor 2.

[0025] In one embodiment of the present invention, the collector ring power transmission device 7 includes a collector outer ring 10, a collector inner ring and a cable assembly. The collector ring power transmission device 7 can be installed at the hub center of the upper rotor 1 and the lower rotor 2 respectively; by way of example, at the upper rotor 1, the collector outer ring 10 and the rotor shaft are fitted with an interference fit, and the leads on both sides of the collector outer ring 10 are connected to the connecting wires 9 led out of the solar thin-film battery 8, and the collector inner ring leads are connected to the controller 3 leads through a sleeve bundle for transmitting solar power generation.

[0026] In one embodiment of the present invention, the coaxial twin-rotor UAV may also include a perception system, a control system, and a communication system, etc., to maintain the integrity of the UAV system functions. Among them, the perception system includes a preset type of sensor module, which is used to perceive information and feed it back to the control system or output through the communication system; the preset type of sensor module includes one or more of an attitude sensor, a position sensor, an orientation sensor, an image sensor, and a temperature sensor; wherein the attitude sensor is used to measure the angular velocity and angular acceleration attitude of the coaxial twin-rotor UAV in three directions; the position sensor is used to measure the position information of the UAV; the orientation sensor is used to measure the head direction of the UAV; the image sensor is used to perceive and record the environment around the coaxial twin-rotor UAV; the temperature sensor is used to perceive the temperature of the environment around the coaxial twin-rotor UAV.

[0027] In one embodiment of the present invention, the light sensor 6 is arranged on the upper side of the center of the hub of the upper rotor 1; when the light intensity of sunlight is greater than or equal to 200 W / m² to 300 W / m² and the battery 4 is not full, the solar film battery 8 is turned on to charge the battery 4; conversely, when the light intensity of sunlight is less than 200 W / m² to 300 W / m², the solar film battery 8 is turned off to avoid damage to the battery 4 due to unstable charging.

[0028] In one embodiment of the present invention, the solar thin-film cell 8 is laid on the upper surface of the blade, with a distance of 2mm to 3mm from the edge of the blade, and a transparent protective layer is laid on the upper surface of the solar thin-film cell 8, which can both transmit light and protect the solar thin-film cell 8 from damage by foreign objects such as rain, snow, wind and sand, thereby improving reliability and service life.

[0029] In one embodiment of the present invention, the coaxial twin-rotor UAV is also provided with a vibration energy collection device; wherein, the vibration energy collection device is used to convert the vibration energy of water into electrical energy and store it in the battery 4 when the coaxial twin-rotor UAV is in water; further, the coaxial twin-rotor UAV is also provided with an offshore floating system, and the offshore floating system is used to realize the floating or diving of the coaxial twin-rotor UAV in water.

[0030] The further preferred technical solution of the embodiment of the present invention is applicable to the sea and air fields. It can perform long-duration flights on the sea surface and float for a long time in the sea water, which expands the application scenarios and improves practicality.

[0031] Sea-air cross-domain aircraft have both the functions of sea navigation and sky flight, and are widely used in the fields of maritime reconnaissance, underwater detection, sea-skimming search and rescue. In recent years, with the continuous deepening of the application of sea-air cross-domain aircraft, the impact effect they are subjected to during the process of entering and exiting the water has attracted much attention, which to a certain extent inhibits the full performance of the aircraft. The impact effect of water is inevitable when cross-domain aircraft enter and exit the water. On the one hand, it will greatly weaken the overall energy of the drone and reduce the navigation or flight speed of the drone. On the other hand, it will greatly impact the body parts of the drone, which may seriously cause damage to mechanical / electrical components (such as damage to the conformal structure of blades and solar thin-film cells), affecting the normal operation of the drone function.

[0032] In an embodiment of the present invention, a method for controlling water entry and exit of a coaxial dual-rotor UAV is disclosed, which specifically includes the following four processes: When entering the water from the air, when it is above a preset height above the water surface (such as 2 meters above the water surface), the coaxial twin-rotor drone descends obliquely at an angle of 30° to 60°; after reaching the preset height above the water surface, the coaxial twin-rotor drone descends vertically and continuously reduces the rotation speed of the upper rotor 1 and the lower rotor 2; after touching the water surface, the rotation speed of the upper rotor 1 drops to zero, and the lower rotor 2 rotates at a first preset constant low speed; When in water, the coaxial twin-rotor drone moves by adjusting the collective pitch and cyclic pitch of the lower rotor 2; When entering the air from the water, the lower rotor 2 of the coaxial twin-rotor drone adopts a second preset constant low speed, and moves upward by controlling the variable collective pitch and cyclic variable pitch of the lower rotor 2. When reaching the preset underwater depth, the upper rotor 1 of the coaxial twin-rotor drone starts to rotate and gradually increases the speed, and the lower rotor 2 also gradually increases the speed, and breaks through the water obliquely at an angle of 15° to 30° through the variable collective pitch and cyclic variable pitch of the lower rotor 2; after breaking through the water, the coaxial twin-rotor drone flies obliquely to a certain height, and the upper rotor 1 and the lower rotor 2 are respectively at a constant high speed to balance the torque, and the upper rotor 1 changes the speed and the lower rotor 2 changes the collective pitch and cyclic variable pitch to maintain a stable posture; When in the air, the coaxial twin-rotor drone controls its yaw / fixed-point rotation by adjusting the rotor speed, controls its vertical take-off and landing by adjusting the rotor collective pitch, and controls its pitch or roll motion by adjusting the rotor cyclic pitch.

[0033] The coaxial UAV water entry and exit control method disclosed in the embodiment of the present invention is applicable to sea-air cross-domain aircraft, which can not only buffer the impact energy of the UAV entering and exiting the water, but also reduce the impact damage of the UAV entering and exiting the water. Among them, the coaxial twin-rotor UAV enters the water at a vertical angle and exits the water at an oblique angle. This technical means reduces the energy loss and impact damage of the UAV, expands the application scenarios, and improves practicality.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A coaxial twin-rotor UAV, characterized in that: include: A structural platform (5), a power system, an upper rotor (1), a lower rotor (2) and a solar power generation system; wherein: The power system is fixedly arranged on the structural platform (5); the upper rotor (1) and the lower rotor (2) are arranged on the structural platform (5) via the same rotor shaft; and a transmission component is arranged between the power system and the upper rotor (1) and the lower rotor (2); The upper rotor (1) and the lower rotor (2) both comprise blades and a hub, the blades being mounted on the hub, and the hub being arranged at the center of the rotor to support the blades for rotation and pitch change; wherein the directions of the rotational movements of the upper rotor (1) and the lower rotor (2) are opposite; the rotation speed of the upper rotor (1) is adjustable, and the rotation speed of the lower rotor (2) is adjustable and capable of variable total pitch and cyclic pitch change; The solar power generation system is installed on the structural platform (5), and comprises a solar thin-film battery (8), a collector ring power transmission device (7), a controller (3), a light sensor (6) and a storage battery (4); wherein the light sensor (6) is used to obtain the light intensity of sunlight and input it into the controller (3); the solar thin-film battery (8) is fixedly arranged on the upper surfaces of the blades of the upper rotor (1) and the lower rotor (2); the solar thin-film battery (8) is connected to the collector ring power transmission device (7) via a connecting line (9), and the connecting line (9) is led out from the root of the blade; one side of the controller (3) is connected to the collector ring power transmission device (7), and the other side is connected to the storage battery (4), and is used to control the opening and closing of the solar thin-film battery (8) according to the light intensity; the storage battery (4) is used to supply power to the power system.

2. A coaxial twin-rotor UAV according to claim 1, characterized in that: The power system includes a motor system and a steering gear system; The motor system comprises a first motor and a second motor respectively used to provide rotational power to the upper rotor (1) and the lower rotor (2); and the steering gear system is used to adjust the pulling direction of the rotor discs of the upper rotor (1) and the lower rotor (2).

3. The coaxial twin-rotor UAV according to claim 1, characterized in that: The collector ring power transmission device (7) is installed at the hub center of the upper rotor (1) and the lower rotor (2); The collector ring power transmission device (7) comprises a collector outer ring (10), a collector inner ring and a cable assembly.

4. The coaxial twin-rotor UAV according to claim 1, characterized in that: In the controller (3), when the sunlight intensity is greater than or equal to 200 W / m² to 300 W / m² and the storage battery (4) is not fully charged, the solar thin-film battery (8) is turned on to charge the storage battery (4); otherwise, the solar thin-film battery (8) is turned off.

5. The coaxial twin-rotor UAV according to claim 1, characterized in that: The upper surface of the solar thin-film cell (8) is provided with a transparent protective layer.

6. The coaxial twin-rotor UAV according to claim 1, characterized in that: Also includes: A vibration energy collection device is installed on the structural platform (5) and is used to convert the vibration energy of water into electrical energy and store it in a storage battery (4) when the coaxial twin-rotor drone is in water.

7. The coaxial twin-rotor UAV according to claim 1, characterized in that: Also includes: An offshore floating system, the offshore floating system is installed on the structural platform (5) and is used to achieve floating or diving of the coaxial twin-rotor drone when the coaxial twin-rotor drone is in water.

8. A method for controlling water entry and exit of a coaxial twin-rotor UAV according to claim 1, characterized in that: include: When entering the water from the air, the coaxial twin-rotor drone descends obliquely at a first preset angle when it is above a preset height above the water surface; After reaching a preset height above the water surface, the coaxial twin-rotor drone descends vertically and continuously reduces the rotation speeds of the upper rotor (1) and the lower rotor (2); after touching the water surface, the rotation speed of the upper rotor (1) drops to zero, and the lower rotor (2) rotates at a first preset constant low rotation speed; When entering the air from water, the lower rotor (2) of the coaxial twin-rotor drone adopts a second preset constant low rotation speed and realizes floating movement by controlling the variable collective pitch and the cyclic variable pitch; when reaching the preset underwater depth, the upper rotor (1) of the coaxial twin-rotor drone starts to rotate and gradually increases the rotation speed, and the lower rotor (2) also gradually increases the rotation speed, and breaks through the water obliquely at a second preset angle through the variable collective pitch and the cyclic variable pitch of the lower rotor (2); after breaking through the water, the coaxial twin-rotor drone flies obliquely to a certain height, and the upper rotor (1) and the lower rotor (2) are respectively at a constant high rotation speed to balance the torque, and the posture is kept stable through the variable rotation speed of the upper rotor (1) and the variable collective pitch and the cyclic variable pitch of the lower rotor (2).

9. The method for controlling water entry and exit of a coaxial twin-rotor UAV according to claim 8, characterized in that: The first preset angle has a value range of 30° to 60°.

10. The method for controlling water entry and exit of a coaxial twin-rotor UAV according to claim 8, characterized in that: The second preset angle has a value range of 15° to 30°.

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