A vector tilt coaxial twin-rotor UAV

Abstract

A vector tilting coaxial twin-rotor UAV is provided, which is composed of a fuselage (101), a power device (102) and a vector tilting device (103), wherein the power devices (102) and the vector tilting devices (103) on the left and right sides of the UAV are symmetrical and have completely the same structure. The problem of the rearward blade stalling caused by the high-speed forward flight of the UAV can be solved by the characteristics that the upper and lower rotors rotate at opposite speeds and the rearward blades are symmetrically located relative to the body; the roll moment generated by one rotor is balanced by the roll moment of the other rotor.

Description

Technical Field

[0001] The present invention relates to a coaxial dual-rotor UAV capable of vertical take-off and landing, and in particular to the technical field of a vector-tilt quad-rotor UAV. Background Art

[0002] In recent years, drone technology has continued to develop and improve, and has been widely used in both commercial and military fields. Most traditional coaxial twin-rotor drones use two or more motors connected to reducers and other mechanisms. The two output shafts of the reducer with opposite directions are connected to the upper and lower rotors respectively to achieve reverse rotation of the upper and lower rotors, so that the reaction of the two rotors cancels each other out. However, in the existing technology, the diameter and shape of the upper and lower rotors of traditional coaxial twin-rotor drones are exactly the same, resulting in low flight efficiency, a very complex mechanical structure, and low safety. Summary of the invention

[0003] In view of the defects of the prior art, the present invention proposes a vector tilt coaxial twin-rotor UAV, which can effectively solve some difficulties in safety design such as the complex mechanical structure and large number of parts of the current traditional coaxial twin-rotor power assembly.

[0004] The vector tilting coaxial dual-rotor UAV of the present invention is composed of a fuselage 101, a power device 102 and a vector tilting device 103. The power devices 102 and vector tilting devices 103 on the left and right sides of the UAV are symmetrical and have the same structure; it is characterized by

[0005] The fuselage 101 is divided into a fuselage shell, an upper part of the fuselage, an inner part of the fuselage, a lower part of the fuselage, a left arm sleeve 201 and a right arm sleeve 207; wherein the fuselage shell is a rectangular parallelepiped structure, including a fuselage upper plate 202 located at the upper part of the fuselage shell, a fuselage bottom plate 219, a left side wall 218 and a right side wall 220; the left side wall 218 is fastened to the fuselage upper plate 202 and the fuselage bottom plate 219 by a first fixing connection device; the fuselage upper plate 202 is fastened to the left side wall 218 and the right side wall 220 by a second fixing connection device; similarly, the right side wall 220 is fixed in the same manner as the fuselage bottom plate 219;

[0006] In the upper part of the fuselage, a GPS navigation receiving antenna base 222 is installed on the fuselage upper plate 202. When viewed from the front, the antenna base 222 is in an inverted "T" shape, which is a conventional antenna base shape. It is fastened to the fuselage upper plate 202 by a third fixing connection device; an antenna rod 223 is connected to the antenna base 222. The antenna rod 223 has threads at both ends, the lower end is connected to the antenna base 222, and the upper end is connected to the horizontal disk 204; the antenna rod 223 is coaxial with the base 222 and the horizontal disk 204, and cannot rotate; the GPS is fixed on the upper surface of the horizontal disk 204;

[0007] A small rotor is installed on the upper plate 202 of the fuselage. The small rotor is composed of a rotor mounting cap 205, rotor blades 203 and a brushless DC motor 206 from top to bottom. The brushless DC motor 206 is fastened to the upper plate 202 of the fuselage of the UAV through a fourth fixed connection device. The rotor mounting cap 205, the rotor blades 203 and the brushless DC motor 206 are connected to each other in a conventional manner.

[0008] The fixed antenna base 222 and the brushless DC motor 206 are both located on the longitudinal center axis of the upper plate 202 of the drone fuselage;

[0009] The internal part of the fuselage is equipped with a flight controller 212, a data transmitter 221, four electronic speed regulators 208, 209, 216, 217, steering gears 211, 213 and a battery 214; the flight controller 212 is the control center of the UAV, which is installed inside the fuselage. After receiving the command, it controls the brushless DC motor 206 to make corresponding actions according to the corresponding requirements to change the flight attitude of the UAV; the data transmitter 221 is installed inside the fuselage; the electronic speed regulators 208, 209, 216, 217 use brushless electric regulation, which controls the motor speed after receiving the start, stop and brake signals. The placement of the four electronic speed regulators should take into account the weight of the fuselage; the installation position of the battery 214 is determined by the weight balance of the UAV; the steering gears 211, 213 are installed on both sides of the flight controller, and are fixed on the bottom plate of the fuselage according to the weight, driving the transmission shaft to rotate, thereby realizing the tilting of the power unit and changing the flight attitude of the UAV;

[0010] The lower part of the fuselage has two carbon fiber tripods 210 and 215, which are symmetrically installed under the fuselage bottom plate along the flight direction. The upper parts of the carbon fiber tripods 210 and 215 are arched. The arched tops of the arched carbon fiber tripods 210 and 215 are fastened to the fuselage bottom plate through a fifth fixing connection device or an adhesive. A horizontal carbon fiber tube passes through both ends of the arched carbon fiber tube.

[0011] The left arm sleeve 201 and the right arm sleeve 207 are both hollow long cylindrical rods, fixedly connected to the side wall of the drone as a whole, and symmetrical on both sides; the right end of the left arm sleeve 201 is fixedly connected to the left side wall 218 of the body as a whole, and the left end of the left arm sleeve 201 is connected to the left vector tilt device 103;

[0012] The vector tilt device 103 includes a set on the left and right sides, and the two sets have the same structure and are symmetrically placed; the right vector tilt device 103 generally includes: a tilt mechanism transmission shaft 303, a first bearing 302, a right arm sleeve 207, a right side wall 220, a second bearing 301, and a steering gear 213 from right to left;

[0013] The transmission shaft 303 of the tilt mechanism is a bearing structure. The left and right ends of the right arm sleeve 207 are respectively embedded in the second and first bearings 301 and 302. The transmission shaft 303 of the tilt mechanism is sleeved in the right arm sleeve 207 through the two bearings to reduce the resistance of the transmission shaft to drive the power unit to rotate. The axis of the tilt mechanism transmission shaft 303 coincides with the axis of the two bearings; the right end of the tilt mechanism transmission shaft 303 has a protruding connection part, which is connected to the power unit 102 through the protruding connection part; the left end of the tilt mechanism transmission shaft 303 is rotatably connected to the steering gear 213 inside the UAV fuselage, and the steering gear 213 is connected to the transmission shaft 303 through a rotatable connection; the steering gear 213 drives the transmission shaft 303 to rotate, thereby controlling the right power unit to achieve tilting; the tilt mechanism transmission shaft 303 and the arm sleeve 207 are both hollow structures;

[0014] The power devices on the left and right sides of the drone have the same structure and are arranged symmetrically. The left power device 102 is composed of an upper rotor blade locking mechanism 402, an upper rotor blade 401, an upper motor 403, an upper motor seat gasket 405, a motor bracket 404, a lower motor seat gasket 406, a lower motor 407, a lower rotor blade 408, and a lower rotor blade locking mechanism 409 from top to bottom.

[0015] The upper motor 403 is fixedly connected to the motor seat gasket 405 through the sixth fixed connection device, and the upper motor 403 is located above the upper motor seat gasket 405; the upper rotor blade 401 is fixed to the upper end of the rotor of the upper motor 403, and the rotation of the rotor drives the rotor to rotate and generate lift; the upper rotor blade locking mechanism 402 is installed on the rotor of the upper motor 403, and is used to lock the blade to prevent it from loosening; the lower motor 407 is fixedly connected to the lower motor seat gasket 406, and the lower motor 407 is located below the lower motor seat gasket 406; the lower rotor blade 408 is fixed to the rotor of the lower motor 407, and the rotation of the rotor drives the rotor Rotate to generate lift; the shape and function of the lower rotor blade locking mechanism 409 are the same as those of the upper rotor blade locking mechanism 402, and are installed on the rotor of the lower motor 407; the right ends of the upper and lower motor seat gaskets 405 and 406 are respectively fixedly connected to the tilt mechanism transmission shaft 410 on the left side through the seventh fixed connection device; the left ends of the upper and lower motor seat gaskets 405 and 406 are fixedly connected to the motor bracket 304 through the eighth fixed connection device, and the motor bracket 404 makes the upper and lower motors more securely fixed; and the axis of the upper motor 403 coincides with the axis of the lower motor 407 to ensure that the lift generated by the rotor is maximized.

[0016] In a specific embodiment of the present invention, four electronic speed regulators are fixed at four corner positions of the machine body bottom plate.

[0017] In one embodiment of the present invention, the left end of the tilt mechanism transmission shaft 303 is rotatably connected to the steering gear 213 inside the UAV fuselage by means of a rotational connection, a threaded connection or a pivot connection.

[0018] In a specific embodiment of the present invention, the transmission shaft 303 is made of carbon fiber; the fuselage material is selected from aluminum alloy or carbon fiber; and the rotor blades are all made of carbon fiber blades.

[0019] In a specific embodiment of the present invention, the upper motor 403 and the lower motor 407 are symmetrically installed up and down to form a dual-rotor mechanism.

[0020] In one embodiment of the present invention, the motor model is selected as 2212, 3508 or 4010.

[0021] In a specific embodiment of the present invention, the motor model is selected 3508.

[0022] A method for analyzing the weight of the above-mentioned coaxial dual-rotor UAV is also provided: the total take-off weight of the UAV can be expressed as: Where M is the total weight of the aircraft, M d is the battery weight, M p is the power system weight, M e Electronic equipment weight, M l is the load weight, X sis the structural weight factor; for small, low-speed tilt-rotor UAVs, X s The value is between 0.4-0.5.

[0023] A design method for the above-mentioned coaxial twin-rotor UAV rotor type is provided: the upper rotor blade 401 and the lower rotor blade 408 are both double-bladed arc-shaped long thin sheets with a certain twist rate; the rotor disk load is an important parameter of the rotor, which can be expressed as: M is the total weight of the aircraft, S y is the effective area of ​​the rotor disc; the coaxial twin-rotor structure will produce turbulence during operation, which will reduce the effective area of ​​the disc. In order to facilitate the calculation of the effective area of ​​the coaxial twin-rotor disc, a correction factor λ is introduced. Therefore, the effective area of ​​the rotor is expressed as: S y =Kλπ(R1 2 +R2 2 ), where R1 is the rotation radius of the upper rotor blade 401, R2 is the rotation radius of the lower rotor blade 408, and K is the effective coefficient of the rotor disc area; the conditions that must be met for the drone to take off are: Among them, η0 is the hovering effectiveness coefficient, D is the diameter of the effective area of ​​the double rotor; the upper rotor blade 401 and the lower rotor blade 408 have different radii. By increasing the lower rotor blade 408, the upper and lower rotors rotate at the same speed and in opposite directions to generate the same force, thereby ensuring the stability of the drone.

[0024] In a specific embodiment of the present invention, the rotor disc correction coefficient is 0.75, the effective coefficient is 0.95, η0=0.75; the radius of the lower rotor blade 408 is 0.16m, the radius of the upper rotor blade 401 is 0.12m; the effective area S of the rotor disc y 0.38m 2 The fuselage is made of a composite material of AS4 and PEEK. The fuselage of the drone is a hollow rectangular structure with parameters of: 25cm long, 20cm wide and 15cm high.

[0025] The present invention improves the power system and has a unique appearance design of the UAV. Two brushless DC motors are symmetrically installed on the upper and lower sides of the left and right sides of the UAV, and rotate in opposite directions to realize a dual-rotor mechanism, which greatly simplifies the traditional complex mechanical coaxial dual-rotor mechanism. The upper and lower rotors are of different sizes, which ensures that the upper and lower rotors rotate in opposite directions at the same speed, so that the UAV can fly stably and improve flight efficiency. At the same time, compared with the symmetry of the traditional tilt-rotor arranged left and right and reversed, the symmetry of the reversed coaxial dual rotors can also effectively solve the following two problems: 1. The stall problem of the rearward blade caused by the high-speed forward flight of the UAV can be solved by the opposite rotation speed of the upper and lower rotors and the symmetric position of the rearward blades relative to the body; 2. The roll torque generated by one rotor is balanced by the roll torque of the other rotor. Therefore, the vector-tilting quad-rotor UAV designed by the present invention has the advantages of high hovering efficiency, the ability to maintain self-rotation and glide, a simple tilting mechanism, and high safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is the overall structure diagram of the vector tilt-rotating quad-rotor UAV of the present invention;

[0027] Figure 2 The vector tilt quad-rotor UAV fuselage structure of the present invention is Figure 2 (a) shows a front view;

[0028] Figure 2 (b) shows a left side view, Figure 2 (c) shows a top view;

[0029] Figure 3 This is a structural diagram of a power device of a vector tilt-rotating quad-rotor UAV of the present invention;

[0030] Figure 4 It is a structural diagram of a vector tilt device of a vector tilt quad-rotor UAV of the present invention;

[0031] Figure 5 It is a schematic diagram of a rotor blade of the present invention. DETAILED DESCRIPTION

[0032] In order to make the concept, specific structure and beneficial effects of the present invention more clear, the features and effects of the present invention are fully described in conjunction with the following embodiments and drawings. It should be understood that the specific embodiments described herein are only used to describe the present invention, and are not used to limit the present invention.

[0033] like Figure 1 As shown, the vector tilt coaxial twin-rotor UAV is composed of a fuselage 101, a power unit 102 and a vector tilt device 103. The power unit 102 and the vector tilt device 103 on the left and right sides of the UAV are symmetrical and completely the same.

[0034] like Figure 2 As shown, the fuselage 101 is mainly divided into a fuselage shell, an upper fuselage part, an internal fuselage part, a lower fuselage part, a left arm sleeve 201 and a right arm sleeve 207 .

[0035] The fuselage shell is a hollow shell structure, and the shell itself can be a rectangular parallelepiped structure, a shell-like sphere or other polygonal structures with a symmetrical structure. The fuselage shell includes a body upper plate 202 located at the upper part of the fuselage shell, a body bottom plate 219, a left side wall 218, and a right side wall 220. In one embodiment of the present invention, the fuselage shell is a rectangular parallelepiped structure, such as Figure 2 As shown in (b), four screw holes are opened on the left side wall 218, and the left side wall 218 is fastened to the upper plate 202 and the bottom plate 219 of the machine body by screws; Figure 2 (c) As shown in the top view, six screw holes are opened on the upper plate 202 of the fuselage, and screws are used to fasten the upper plate 202 of the fuselage with the left side wall 218 and the right side wall 220. Similarly, the right side wall 220 and the fuselage bottom plate 219 are fixed in the same way to ensure the reliability of the entire fuselage of the drone.

[0036] In the upper part of the fuselage, about the middle and rear of the upper fuselage shell, a GPS navigation receiving antenna base 222 is installed on the upper plate 202 of the fuselage. When viewed from the front, the antenna base 222 is in an inverted "T" shape, which is a conventional antenna base shape. For example, four screws are used to fasten it to the upper plate 202 of the fuselage. An antenna rod 223 is connected to the antenna base 222. The upper and lower ends of the antenna rod 223 are engraved with threads. The lower end is connected to the antenna base 222, and the upper end is connected to a horizontal disk 204. The antenna rod 223 is coaxial with the base 222 and the horizontal disk 204, and cannot rotate. It has a simple structure, reliable connection, and convenient disassembly and assembly. The GPS is installed on the upper surface of the horizontal disk 204. In practice, the two are usually bonded by an adhesive such as 3M glue.

[0037] A small rotor is installed on the upper plate 202 of the fuselage approximately in the middle and front above the fuselage shell. The small rotor is composed of a rotor mounting cap 205, rotor blades 203 and a brushless DC motor 206 from top to bottom. The brushless DC motor 206 is fastened to the upper plate 202 of the fuselage of the drone, for example, by four screws. Its function is to ensure the balance of the fuselage during the flight of the drone and to achieve the change of the pitch attitude of the drone. The connection between the rotor mounting cap 205, the rotor blades 203 and the brushless DC motor 206 is a conventional connection, which is well known to those skilled in the art.

[0038] The fixed antenna base 222 and the brushless DC motor 206 are both roughly located on the longitudinal (flight direction) center axis of the upper panel 202 of the drone fuselage.

[0039] The internal part of the fuselage is equipped with a flight controller 212, a data transmitter 221, four electronic speed regulators 208, 209, 216, 217, steering gears 211, 213 and a battery 214. The flight controller 212 is the control center of the UAV, which is installed at the center of gravity inside the fuselage. After receiving the command, it controls the brushless DC motor 206 to make corresponding actions according to the corresponding requirements to change the flight attitude of the UAV; the data transmitter 221 is installed in the edge area inside the fuselage to facilitate the transmission of data, pictures or videos between the UAV and the ground station or remote control equipment; the electronic speed regulators 208, 209, 216, 217 use brushless electric regulation, and after receiving the start, stop and brake signals, they realize the control of the motor speed. The placement of the four electronic speed regulators should take into account the weight of the fuselage; in one embodiment of the present invention, the four electronic speed regulators are fixed at the four corners of the fuselage bottom plate. The battery 214 is the power source of the UAV. The capacity is generally determined by the UAV load, and the installation position is determined by the weight balance of the UAV. The battery 214 usually uses a lithium battery. The servos 211 and 213 are installed on both sides of the flight controller and fixed on the bottom plate of the fuselage according to the counterweight, driving the transmission shaft to rotate, thereby realizing the tilting of the power unit and changing the flight attitude of the UAV.

[0040] The lower part of the fuselage has two carbon fiber tripods 210 and 215, which are installed symmetrically below the fuselage bottom plate along the flight direction. Figure 2 As shown in (b), the upper part of the carbon fiber tripod 210, 215 is in an arched shape, and the arched top of the arched carbon fiber tripod 210, 215 is tightly connected to the bottom plate of the fuselage; a horizontal carbon fiber tube passes through the two ends of the arched carbon fiber tube to increase the ground contact area of ​​the drone, and plays a role in supporting the drone when the drone takes off and lands to prevent the drone from tipping over. The horizontal carbon fiber tubes extend from the two ends of the arched carbon fiber tube, and a sponge sleeve is placed on each of the two extended ends of the horizontal carbon fiber tube to effectively play a shock-absorbing role. In one embodiment of the present invention, a small hole is drilled in the arched top of the arched carbon fiber tripod 210, 215, and screws are used to fasten it to the bottom plate of the drone.

[0041] UAV weight analysis is an important part of the aircraft design process. Its total weight determines the fuselage structure size, material, and motor power requirements. The total takeoff weight of the UAV can be expressed as: Where M is the total weight of the aircraft, M d is the battery weight, M p is the power system weight, M e Electronic equipment weight, M l is the load weight, X s The tilt-rotor UAV designed by the present invention is a small-sized, low-speed aircraft. According to statistics and experience, X sThe value of is about 0.4-0.5. In one embodiment of the present invention, the take-off weight of the drone is 3.5Kg, the load capacity of the drone is 0.5Kg, and X s The value is 0.45. It means that the total weight of the battery, power system and electronic equipment cannot exceed 1.4Kg, and it can be calculated that the weight of the fuselage structure does not exceed 1.5Kg. The fuselage material can be selected from aluminum alloy materials or carbon fiber, etc. In one embodiment of the present invention, preferably, a composite material of AS4 and PEEK is used, which is directly melt-cast and molded, with light weight, high strength and low cost. The fuselage of the drone is a hollow rectangular structure with parameters of: 25cm long, 20cm wide and 15cm high.

[0042] The left arm sleeve 201 and the right arm sleeve 207 are both hollow long cylindrical rods, fixedly connected to the side wall of the drone as a whole, and symmetrical. The left arm sleeve 201 is taken as an example for description. Figure 2 As shown in (b), the right end of the left arm sleeve 201 is fixedly connected to the left side wall 218 of the body as a whole, and the left end of the left arm sleeve 201 is connected to the left vector tilt device 103.

[0043] The vector tilt device 103 includes a set on the left and right sides, and the two sets have the same structure and are symmetrically placed. Figure 3 As shown, the right vector tilt device 103 is taken as an example for description. As can be seen from the figure, the right vector tilt device 103 generally includes: a tilt mechanism transmission shaft 303, a first bearing 302, a right arm sleeve 207, a right side wall 220, a second bearing 301, and a steering gear 213 from right to left.

[0044] The transmission shaft 303 of the tilt mechanism is a bearing structure. The left and right ends of the right arm sleeve 207 are respectively embedded in the second and first bearings 301 and 302. The transmission shaft 303 of the tilt mechanism is sleeved in the right arm sleeve 207 through these two bearings to reduce the resistance of the transmission shaft to drive the power unit to rotate. The axis of the transmission shaft 303 of the tilt mechanism coincides with the axis of the two bearings. The right end of the transmission shaft 303 of the tilt mechanism has a protruding connection portion, which is connected to the power unit 102 through the protruding connection portion. The structure of the protruding connection portion of the transmission shaft 303 of the tilt mechanism and the connection method with the power unit 102 are well known to those skilled in the art and will not be repeated. The connection method between the transmission shaft 303 of the tilt mechanism, the right arm sleeve 207, the bearing 301, and the bearing 302 is also well known to those skilled in the art. Through the diagram and the above text description, those skilled in the art can easily know the connection relationship and working principle between these components and will not be repeated. The left end of the tilt mechanism transmission shaft 303 is rotatably connected to the servo 213 inside the UAV fuselage, and the connection method can be a rotation connection, a threaded connection or a pivot connection. In one embodiment of the present invention, the servo 213 is connected to the transmission shaft 303 by a threaded connection. The servo 213 drives the transmission shaft 303 to rotate, and then controls the right power device to achieve tilting, so as to achieve the purpose of controlling the posture and movement of the UAV. In the present invention, the tilt mechanism transmission shaft 303 and the arm sleeve 207 are both hollow structures, and the transmission shaft 303 material is carbon fiber to reduce the weight of the UAV itself. Electric adjustment line holes are opened on the motor seat gaskets 405, 406 (as described in detail later) and the transmission shaft 410 for the layout of the line, and it does not affect the normal operation of the vector tilt mechanism. This is well known to those skilled in the art and will not be repeated.

[0045] Figure 4 A schematic diagram of a power device 102 is shown. Since the power devices on the left and right sides of the drone have the same structure and are arranged symmetrically, the left power device 102 is used as an example for description. The left power device 102 is composed of an upper rotor mounting cap 402, an upper rotor blade 401, an upper motor 403, an upper motor seat gasket 405, a motor bracket 404, a lower motor seat gasket 406, a lower motor 407, a lower rotor blade 408, and a lower rotor mounting cap 409 from top to bottom.

[0046] The upper motor 403 and the lower motor 407 are symmetrically installed up and down to form a double rotor mechanism, which provides the lift required for the flight of the drone and various changes in posture. In one embodiment of the present invention, the motor model can be selected as 2212, 3508, and 4010, preferably, the model is selected as 3508. As shown in the figure, the upper motor 403 is fixedly connected to the motor seat gasket 405, for example, by screw fastening connection, and the upper motor 403 is located on the upper motor seat gasket 405. The upper rotor blade 401 is fixed to the upper end of the rotor of the upper motor 403, and the rotor rotates to drive the rotor to rotate and generate lift. The upper rotor mounting cap 402 is in the shape of a semi-spherical ball, the interior is hollowed out and the threads are carved inside, and it is installed on the rotor of the upper motor 403 by threads to lock the blades and prevent them from loosening. The lower motor 407 is fixedly connected to the lower motor seat gasket 406, and the lower motor 407 is located below the lower motor seat gasket 406. The lower rotor blade 408 is fixed to the rotor of the lower motor 407, and the rotation of the rotor drives the rotor to rotate, generating lift. The shape and function of the lower rotor mounting cap 409 are the same as those of the upper rotor mounting cap 402, and it is mounted on the rotor of the lower motor 407 by threads. The right ends of the upper and lower motor seat gaskets 405 and 406 are respectively fixedly connected to the left tilt mechanism transmission shaft 410, for example, the right ends of the upper and lower motor seat gaskets 405 and 406 each have a screw hole, which fits tightly with the left tilt mechanism transmission shaft 410, and is fixed by screws inserted from top to bottom; the left ends of the upper and lower motor seat gaskets 405 and 406 are fixedly connected to the motor bracket 304 by a fixing connection device such as two upper and lower screws, and the motor bracket 404 makes the upper and lower motors more securely fixed. In addition, the axis of the upper motor 403 coincides with the axis of the lower motor 407 to ensure that the lift generated by the rotor is maximized.

[0047] Figure 5 The rotor blade schematic diagram is shown. The design and selection of the type of UAV rotor is crucial to the flight aerodynamics of the entire aircraft. The rotor blades in the present invention are all made of carbon fiber blades with light weight and high hardness. The upper rotor blade 401 and the lower rotor blade 408 are both double-bladed arc-shaped long thin sheets with a certain twist rate. The propeller disk load is an important parameter of the rotor and can be expressed as: S y The present invention adopts a coaxial twin-rotor structure, which will produce turbulence during operation, reducing the effective area of ​​the rotor disc. In order to facilitate the calculation of the effective area of ​​the coaxial twin-rotor rotor disc, a correction coefficient λ is introduced, so the effective area of ​​the rotor is expressed as: S y =Kλπ(R1 2 +R2 2), where R1 is the rotation radius of the upper rotor blade 401, R2 is the rotation radius of the lower rotor blade 408, and K is the effective coefficient of the rotor disc area. In one embodiment of the present invention, the disc correction coefficient is 0.75, the effective coefficient is 0.95, and the conditions that must be met for the drone to take off are obtained from the literature: Among them, η0 is the hovering effective coefficient, here η0 = 0.75, D is the effective area diameter of the twin rotor. After calculation, it can be obtained that the diameter of the effective area of ​​the coaxial twin rotor propeller disk is D ≥ 0.65m. Here, the diameter of the effective area of ​​the coaxial twin rotor propeller disk is selected as 0.7m, and the effective area is 0.38m 2 . In the present invention, the upper rotor blade 401 and the lower rotor blade 408 have different radii. By increasing the lower rotor blade 408, the upper and lower rotors rotate in opposite directions at the same speed to generate the same force, thereby ensuring the stability of the UAV. In the present invention, the ratio of the upper and lower rotor blade radii is selected to be 3:4. Through calculation, the radius of the lower rotor blade 408 is 0.16m, and the radius of the upper rotor blade 401 is 0.12m. Therefore, when the total weight of the UAV is 3.5Kg, the load of the coaxial twin-rotor propeller is 9.1Kg / m 2 The maximum rotor load of electric rotor drone is 12Kg / m 2 Therefore, the propeller disk of the UAV designed by the present invention is more reasonable and has a certain load margin.

Claims

1. A vector tilt coaxial twin-rotor UAV, comprising a fuselage (101), a power device (102) and a vector tilt device (103), wherein the power devices (102) and the vector tilt devices (103) on the left and right sides of the UAV are symmetrical and have the same structure; characterized in that The fuselage (101) is divided into a fuselage shell, an upper fuselage portion, an inner fuselage portion, a lower fuselage portion, a left fuselage arm sleeve (201) and a right fuselage arm sleeve (207); wherein the fuselage shell is a rectangular parallelepiped structure, comprising a fuselage upper plate (202) located at the upper part of the fuselage shell, a fuselage bottom plate (219), a left side wall (218) and a right side wall (220); the left side wall (218) is fastened to the fuselage upper plate (202) and the fuselage bottom plate (219) by a first fixing connection device; the fuselage upper plate (202) is fastened to the left side wall (218) and the right side wall (220) by a second fixing connection device; similarly, the right side wall (220) and the fuselage bottom plate (219) have the same fixing method; In the upper part of the fuselage, a GPS navigation receiving antenna base (222) is installed on the fuselage upper plate (202). When viewed from the front, the antenna base (222) is in an inverted "T" shape, which is a conventional antenna base shape. It is fastened to the fuselage upper plate (202) by a third fixing connection device; an antenna rod (223) is connected to the antenna base (222), and the antenna rod (223) has threads at both the upper and lower ends. The lower end is connected to the antenna base (222), and the upper end is connected to the horizontal disk (204); the antenna rod (223) is coaxial with the antenna base (222) and the horizontal disk (204), and cannot rotate; the GPS is fixed on the upper surface of the horizontal disk (204); A small rotor is mounted on the upper body plate (202), and the small rotor is composed of a rotor mounting cap (205), rotor blades (203) and a brushless DC motor (206) from top to bottom, and the brushless DC motor (206) is fastened to the upper body plate (202) of the drone via a fourth fixed connection device; the rotor mounting cap (205), the rotor blades (203) and the brushless DC motor (206) are connected to each other in a conventional manner; The fixed antenna base (222) and the brushless DC motor (206) are both located on the longitudinal center axis of the upper plate (202) of the drone fuselage; The interior of the fuselage is provided with a flight controller (212), a data transmitter (221), four electronic speed regulators (208, 209, 216, 217), a first steering gear (211) and a second steering gear (213), and a battery (214); the flight controller (212) is the control center of the UAV, which is installed inside the fuselage and controls the brushless DC motor (206) to perform corresponding actions according to corresponding requirements after receiving instructions, so as to change the flight attitude of the UAV; the data transmitter (221) is installed inside the fuselage; the electronic speed regulators (208, 209, 216, 217) adopt brushless electric regulation and control the motor speed after receiving start, stop and brake signals, and the placement of the four electronic speed regulators should take the weight of the fuselage into consideration; The installation position of the battery (214) is determined by the weight balance of the UAV; the first steering gear (211) and the second steering gear (213) are installed on both sides of the flight controller and fixedly installed on the bottom plate of the fuselage according to the counterweight, driving the transmission shaft to rotate, thereby realizing the tilting of the power device and changing the flight attitude of the UAV; The lower part of the fuselage is provided with two carbon fiber tripods (210, 215), which are symmetrically installed below the fuselage bottom plate along the flight direction. The upper part of the carbon fiber tripods (210, 215) is in an arched shape. The arched top ends of the arched carbon fiber tripods (210, 215) are fastened to the fuselage bottom plate through a fifth fixing connection device or an adhesive. A horizontal carbon fiber tube passes through the two ends of the arched carbon fiber tube. The carbon fiber tripods (210, 215) are The left machine arm sleeve (201) and the right machine arm sleeve (207) are both hollow long cylindrical rods, fixedly connected to the side wall of the drone as a whole, and symmetrical on both sides; the right end of the left machine arm sleeve (201) is fixedly connected to the left side wall (218) of the body as a whole, and the left end of the left machine arm sleeve (201) is connected to the left vector tilt device (103); The vector tilt device (103) comprises a set on each of the left and right sides, the two sets have completely the same structure and are symmetrically placed; the right vector tilt device (103) comprises from right to left: a first tilt mechanism transmission shaft (303), a first bearing (302), a right arm sleeve (207), a right side wall (220), a second bearing (301), and a second steering gear (213); The first tilt mechanism transmission shaft (303) is a bearing structure. The left and right ends of the right machine arm sleeve (207) are respectively embedded with the second and first bearings (301, 302). The first tilt mechanism transmission shaft (303) is sleeved in the right machine arm sleeve (207) through the two bearings to reduce the resistance of the transmission shaft driving the power device to rotate. The axis of the first tilt mechanism transmission shaft (303) coincides with the axis of the two bearings. The right end of the first tilt mechanism transmission shaft (303) has a protruding connection portion. The first tilt mechanism transmission shaft (303) is connected to the power device (102); the left end of the first tilt mechanism transmission shaft (303) is rotatably connected to the second steering gear (213) inside the drone fuselage, and the second steering gear (213) is connected to the first tilt mechanism transmission shaft (303) through a rotatable connection; the second steering gear (213) drives the first tilt mechanism transmission shaft (303) to rotate, thereby controlling the right power device to achieve tilting; the first tilt mechanism transmission shaft (303) and the right arm sleeve (207) are both hollow structures; The power devices on the left and right sides of the drone have the same structure and are arranged symmetrically. The left power device (102) is composed of an upper rotor blade locking mechanism (402), an upper rotor blade (401), an upper motor (403), an upper motor seat gasket (405), a motor bracket (404), a lower motor seat gasket (406), a lower motor (407), a lower rotor blade (408), and a lower rotor blade locking mechanism (409) from top to bottom. The upper motor (403) is fixedly connected to the upper motor seat gasket (405) through a sixth fixed connection device, and the upper motor (403) is located on the upper motor seat gasket (405); the upper rotor blade (401) is fixed to the upper end of the rotor of the upper motor (403), and the rotation of the rotor drives the rotor to rotate, thereby generating lift; the upper rotor blade locking mechanism (402) is installed on the rotor of the upper motor (403) and is used to lock the blade to prevent it from loosening; the lower motor (407) is fixedly connected to the lower motor seat gasket (406), and the lower motor (407) is located under the lower motor seat gasket (406); the lower rotor blade (408) is fixed to the rotor of the lower motor (407), and the rotation of the rotor drives the rotor to rotate. The lower rotor blade locking mechanism (409) has the same shape and function as the upper rotor blade locking mechanism (402) and is installed on the rotor of the lower motor (407); the right ends of the upper motor seat gasket (405) and the lower motor seat gasket (406) are respectively fixedly connected to the second tilt mechanism transmission shaft (410) on the left side through the seventh fixed connection device; the left ends of the upper motor seat gasket (405) and the lower motor seat gasket (406) are fixedly connected to the left motor bracket (304), and the motor bracket (404) makes the upper and lower motors more securely fixed; and the axis of the upper motor (403) coincides with the axis of the lower motor (407) to ensure that the lift generated by the rotor is maximized; and wherein, Four electronic speed regulators are fixed at the four corners of the machine body bottom plate; The left end of the tilt mechanism transmission shaft (303) is rotatably connected to the second steering engine (213) inside the UAV fuselage in a rotating connection, a threaded connection or a pivot connection; The upper motor (403) and the lower motor (407) are symmetrically installed up and down to form a double rotor mechanism; The material of the first tilt mechanism transmission shaft (303) is carbon fiber; the fuselage material is selected from aluminum alloy material or carbon fiber; and the rotor blades are all carbon fiber blades.

2. The vector tilt coaxial twin-rotor UAV according to claim 1, characterized in that: Select motor model 2212, 3508 or 4010.

3. The vector tilt coaxial twin-rotor UAV according to claim 2, characterized in that: Select motor model 3508.

4. The drone weight analysis method of a coaxial dual-rotor drone according to any one of claims 1 to 3, characterized in that: The total take-off weight of the drone is expressed as: Where M is the total weight of the aircraft, M d is the battery weight, M p is the power system weight, M e Electronic equipment weight, M l is the load weight, X s is the structural weight factor; for small, low-speed tilt-rotor UAVs, X s The value is between 0.4-0.

5.

5. The design method of the coaxial twin-rotor UAV rotor type according to any one of claims 1 to 3, characterized in that: The upper rotor blade (401) and the lower rotor blade (408) are both double-bladed long thin arc-shaped blades with a certain twist rate; the rotor disk load is an important parameter of the rotor, which is expressed as: M is the total weight of the aircraft, S y is the effective area of ​​the rotor disc; the coaxial twin-rotor structure will produce turbulence during operation, which will reduce the effective area of ​​the disc. In order to facilitate the calculation of the effective area of ​​the coaxial twin-rotor disc, a correction factor λ is introduced. Therefore, the effective area of ​​the rotor is expressed as: S y =Kλπ(R1 2 +R2 2 ), where R1 is the rotation radius of the upper rotor blade (401), R2 is the rotation radius of the lower rotor blade (408), and K is the effective coefficient of the rotor disc area; the conditions that must be met for the drone to take off are: Wherein, η0 is the hovering effective coefficient, D is the diameter of the effective area of ​​the double rotors; the upper rotor blade (401) and the lower rotor blade (408) have different radii, and by increasing the lower rotor blade (408), the upper and lower rotors rotate at the same speed in opposite directions to generate the same force, thereby ensuring the stability of the UAV.

6. The design method of the coaxial twin-rotor UAV rotor type as claimed in claim 5, characterized in that: The rotor disc correction coefficient is 0.75, the effective coefficient is 0.95, η0=0.75; the radius of the lower rotor blade (408) is 0.16m, the radius of the upper rotor blade (401) is 0.12m; the effective area S of the rotor disc y 0.38m 2 ; The fuselage is made of a composite material of AS4 and PEEK. The fuselage of the drone is a hollow rectangular structure with parameters as follows: 25cm long, 20cm wide, and 15cm high.

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