A land-air amphibious coaxial dual-rotor ducted UAV and motion control method thereof

Abstract

The present invention discloses a land-air amphibious coaxial twin-rotor ducted UAV and a motion control method thereof, comprising a fuselage structure, a power device, an aerodynamic force regulating device and a control computing device. On the ground, the rotor rotates at a low speed to generate airflow, and the control rudder in the airflow rotates to generate thrust to control the body to slide on the ground, and the body direction is controlled by the rotor speed difference; when moving in the air, the rotor rotates at a high speed to generate lift to balance the gravity of the fuselage, and the aerodynamic force and torque are generated by the deflection of the rudder and the rotor speed difference to control the flight of the UAV. The present invention realizes two motion modes of the coaxial ducted UAV, namely, air and ground. The working time of the UAV can be greatly extended by gliding on the ground. By making full use of a set of power systems to avoid introducing additional drive modules, a simple and effective structure and lightweight design are realized, and the UAV has the characteristics of good safety and high hovering efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicle design and control, and in particular to a land-air amphibious coaxial twin-rotor ducted unmanned aerial vehicle and a motion control method thereof. Background Art

[0002] Ducted UAVs are gradually being widely used because of the good safety brought by the ducted rotors. However, they can only fly in the air when performing tasks, and most of the energy is used to overcome gravity, which limits their endurance. Existing land-air amphibious solutions often bring complex structures and additional drive components, increasing the size and energy consumption.

[0003] The invention patent with publication number CN 114834199 A discloses a land-air dual-purpose quad-rotor UAV. The invention patent with publication number CN113199915B discloses a land-air amphibious UAV and its flight control method. The above two designs realize land-air amphibious movement, but require additional drive devices when moving on the ground, which increases energy consumption and weight, and brings additional mechanical structures. The original power system of the UAV is not utilized.

[0004] The invention patent with publication number CN102285449A and the utility model patent with publication number CN211494449U respectively disclose a coaxial twin-rotor ducted UAV and a coaxial twin-propeller ducted UAV, which only have a flight mode and limited endurance. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned defects in the prior art and to provide a land-air amphibious coaxial twin-rotor ducted UAV and its motion control method, which has two motion modes, land and air, uses the same power system and controller, reduces the complex mechanical structure and drive module introduced by adding motion modes, and designs a motion control method suitable for the UAV.

[0006] The first object of the present invention can be achieved by adopting the following technical solutions:

[0007] A land-air amphibious coaxial twin-rotor ducted UAV, the UAV comprises a fuselage structure, a power device, an aerodynamic force regulating device, a control computing device and a battery 7,

[0008] The fuselage structure includes a duct shell 1, a duct base 2, three universal wheels 10, and a top shell 9. The duct shell 1 is a cylindrical shell structure, which is fixed to the duct base 2 by screws through four groups of threaded holes evenly distributed on the duct shell 1. The lower side of the duct base 2 has three groups of protrusions as a support frame, and a threaded hole is provided at the lower end of the support frame. The three universal wheels 10 all have threaded columns, which are connected and fixed to the threaded holes at the lower end of the support frame of the duct base 2. The top shell 9 is installed at the top center position of the duct shell 1 by screws; the fuselage structure and main force-bearing components of the above-mentioned UAV provide an installation position for the power unit / aerodynamic adjustment device / control calculation device, and provide flight and ground gliding hardware on the fuselage structure.

[0009] The power device includes an upper motor 3, an upper rotor 4, a lower motor 5, and a lower rotor 6. The upper motor 3 has a base mounting hole, which is fixedly connected to the upper central position of the inside of the duct shell 1 by screws. The upper rotor 4 has a central threaded hole, which is fixedly connected to the central stud of the upper motor 3 by a nut, and rotates with the upper motor 3; the lower motor 5 has a base mounting hole, which is fixedly connected to the top central position of the duct base 2 by screws, and is located inside the duct shell 1. The lower rotor 6 has a central threaded hole, which is fixedly connected to the central stud of the lower motor 5 by a nut, and rotates with the lower motor 5. The upper rotor 4 and the lower rotor 6 have rotor airfoil shapes, accelerate air flow by rapid rotation, generate lift on the rotor by using the Bernoulli principle, and make the accelerated airflow ejected at high speed from the outlet of the duct base 2, providing the main power for the movement of the UAV.

[0010] The aerodynamic force regulating device comprises four servos 12 and four control surfaces 11, wherein the four servos 12 all have mounting holes, are fixed horizontally to the center of the lower side of the duct base 2 by screws and are arranged in a uniform circle, the rotation axes of the four servos 12 face the outside of the duct base 2, and the four control surfaces 11 are fixedly connected to the four servos 12 in pairs by screws through the mounting holes on the inner side thereof, and are rotated by the drive of the four servos 12; the four control surfaces 11 have airfoils, and when the upper rotor 4 and the lower rotor 6 rotate at high speed to generate airflow that is ejected at high speed through the inner outlet of the duct base 2, the four control surfaces 11 deflect to make the gas flow rates on both sides of the airfoil different, and the Bernoulli principle is used to generate aerodynamic force on the four control surfaces 11, thereby controlling and regulating the motion posture of the UAV during flight and the speed during ground movement;

[0011] The control calculation device includes a control circuit 8, which is installed at the top center of the duct shell 1 through a plastic stud and is located inside the top shell 9. The control circuit receives remote control signals and has attitude and speed sensors. It performs motion control through codes, calculates the rotation speeds of the upper motor 3 and the lower motor 5 and the rotation angles of the four steering gears 12, and sends them to the corresponding upper motor 3, lower motor 5 and four steering gears 12 through data connection lines, thereby realizing the motion control of the UAV;

[0012] The battery 7 is inserted from the top inner opening of the duct shell 1 and fixed on the drone, and is connected to the control circuit 8, the upper motor 3, the lower motor 5 and the four steering gears 12 through a power line.

[0013] Furthermore, the duct shell 1 is a through cylindrical duct cavity, and the top opening of the cavity has an outward-expanding aerodynamic airfoil. When the upper rotor 4 and the lower rotor 6 rotate, the air is accelerated to be sucked into the duct cavity, and flows rapidly on the airfoil at the top opening of the cavity, resulting in different pressures on both sides of the airfoil. The pressure is smaller on the side with a faster flow rate, thereby generating lift at the outward expansion of the duct shell opening. The lift is directed upward, which helps the drone to overcome its own gravity. Eight hollow pillars are evenly distributed in a circle at the top opening of the cavity. The pillars have a load-bearing function. The elliptical hollow through-hole design can provide sufficient support and connection strength in the structure while reducing the weight of the structure. The through hole also provides storage space for the connecting wires of the aircraft, which is convenient for wiring. Eight pillars connect the structural compartment on the upper side of the duct shell 1. A top shell 9 is arranged on the upper side of the structural compartment. The structural compartment is provided with a cavity and a fixed hole. The battery 7 is fixedly installed in the cavity. The structural compartment has a design with an opening on one side to facilitate the installation and replacement of the battery. The upper motor 3 is installed and connected to the duct shell 1 through the fixed hole. The outer surface of the duct cavity has four evenly distributed rectangular depressions on the basis of the cylindrical shell. The protruding part between the depressions has four groups of installation holes near the lower end surface. This design has sufficient structural strength and plays a role in reducing the weight of the structure, and has the function of connecting the duct base 2. The above-mentioned duct shell 1 has achieved multiple beneficial effects by using a single part through complex design on a single part: it bears the force of the main structure, provides installation space and holes, and uses aerodynamic effects to provide lift for the drone. The part is formed in one piece using 3D printing, which can be quickly produced and reduced the weight of the structure.

[0014] Furthermore, the control circuit 8 is fixed on the top of the set top casing 9.

[0015] Furthermore, the duct base 2 has an inner and outer cylindrical shell structure and a cross beam structure connecting the inner and outer rings, wherein the outer cylindrical shell has protrusions at intervals of 120° on the lower side, and a threaded hole is provided in the center of the lower end surface of the protrusion.

[0016] The duct base 2 adopts the concept of fusion design, and the protrusion plays the role of the bottom landing gear in a conventional UAV, providing support for the UAV, and adopts a 120° interval to achieve three-point support, which has a simple structure and good stability. The threaded hole on the lower end face is convenient for installing universal wheels. The outer ring cylindrical shell is distributed with four groups of rectangular protrusions at 90° intervals on the outside. The central positions of these protrusions have installation holes, which cooperate with the lower side installation holes of the duct shell 1, so that the two parts can be easily and quickly connected and fixed, which is convenient for the production and manufacture of UAVs. The bottom of the lower end surface of the inner cylindrical shell is provided with four sets of steering gear fixing platforms, each set of fixing platforms has two rectangular protrusions and a threaded hole in the center of the rectangle, which is used to install and fix four steering gears 12; the outer end of the cross-shaped beam structure is connected to the outer cylindrical shell, and the inner end crosses and intersects with the inner cylindrical shell. The interior of the cross-shaped beam structure is a cavity, which can reduce the weight of the drone. The central intersection of the cross-shaped beam structure has a sinking design and is provided with four sets of mounting holes distributed at 90° intervals, which are used to install the lower motor 5. An aerodynamic force adjustment device is provided below the cross-shaped beam structure. Through the complex design on a single part, a single part is used to provide sufficient installation space and structural strength for multiple driving components such as the lower motor 5, the lower rotor 6, the three universal wheels 10, the four steering gears 12 and the four rudder surfaces 11. At the same time, the design of the landing gear is streamlined and integrated, and it is convenient to connect with the duct shell 1. It is formed in one piece by 3D printing, which has the effect of rapid production and reduction of structural weight.

[0017] The second object of the present invention can be achieved by adopting the following technical solutions:

[0018] A motion control method for a land-air amphibious coaxial twin-rotor ducted UAV, the motion control method comprising air flight motion control and ground sliding motion control, wherein the air flight motion control comprises the following steps:

[0019] S1, the control calculation device receives the flight speed instruction and collects the speed feedback value of the drone through the speed sensor on the control circuit 8;

[0020] S2, the control calculation device calculates the difference between the flight speed command and the UAV speed feedback value, and multiplies it by the air speed gain coefficient, and the obtained value is recorded as the air expected acceleration;

[0021] S3, the control calculation device calculates the expected attitude and expected lift of the UAV from the expected acceleration in the air through the kinematic model of the attitude and lift of the UAV;

[0022] S4, the control calculation device collects the attitude feedback value of the UAV through the attitude sensor on the control circuit 8;

[0023] S5. The control calculation device calculates the difference between the desired attitude and the attitude feedback value, and multiplies it by the air attitude gain coefficient, and the obtained value is recorded as the desired torque;

[0024] S6, the control calculation device calculates the expected rotation speeds of the upper motor 3 and the lower motor 5 and the expected rotation angles of the four steering gears 12 according to the expected torque through the dynamic model of the UAV, and sends the calculation results to the corresponding upper motor 3, the lower motor 5 and the four steering gears 12 through the data transmission line;

[0025] S7, return to step S1, continue to receive the flight speed command and collect the speed feedback value, and calculate the rotation speed of the upper motor 3, the lower motor 5 and the rotation angle of the four steering gears 12 in real time, realize the control of the flight motion until the flight mission is completed, and stop the calculation;

[0026] Wherein, the ground sliding motion control comprises the following steps:

[0027] T1, the control calculation device receives the sliding speed instruction when moving on the ground, and collects the speed feedback value of the drone through the speed sensor on the control circuit 8;

[0028] T2, the control calculation device calculates the difference between the sliding speed command and the UAV speed feedback value, and multiplies it by the ground speed gain coefficient, and the obtained value is recorded as the ground expected acceleration;

[0029] T3, the control calculation device sets the rotation speed of the upper motor 3 and the lower motor 5 to a fixed value through the dynamic model of ground motion, calculates the expected rotation angle of the four steering gears 12 according to the expected ground acceleration, and sends the calculation result to the upper motor 3, the lower motor 5 and the four steering gears 12 through the data transmission line;

[0030] T4, return to step T1, continue to receive the sliding speed command and collect the speed feedback value, and calculate the rotation speed of the upper motor 3, the lower motor 5 and the rotation angle of the four servos 12 in real time to realize the control of the UAV's ground sliding until the movement task is completed, and stop the calculation.

[0031] Furthermore, the kinematic model of the UAV attitude and lift is:

[0032]

[0033]

[0034]

[0035] in, is the roll angle, θ is the pitch angle, T is the lift of the drone, a x ,a y ,a zare the three-axis accelerations in the coordinate system of the drone body respectively; through this kinematic model, the expected acceleration in the air calculated in step S3 in the flight motion control can be brought into the right side of the equation to calculate the expected attitude (expected roll angle and expected pitch angle) and expected lift of the drone;

[0036] By analyzing the force on the UAV, the dynamic model of the UAV can be obtained:

[0037]

[0038]

[0039] Among them, k F1 is the lift coefficient of the upper motor 3, k F2 is the lift coefficient of the lower motor 5, k vane is the aerodynamic coefficient of the rudder surface, k M1 is the torque coefficient of the upper motor 3, k M2 is the torque coefficient of the lower motor 5, l1 is the projection distance from the aerodynamic center of the rudder surface to the center of gravity of the fuselage on the x-axis in the body coordinate system, l2 is the projection distance from the aerodynamic center of the rudder surface to the center of gravity of the fuselage on the z-axis in the body coordinate system, V e is the wind speed at the duct outlet, Ω1 and Ω2 are the rotation speeds of the upper motor 3 and the lower motor 5, δ1 to δ4 are the rotation angles of the four steering gears 12, M = {M x M y M z} T is the three-axis torque in the fuselage coordinate system. Through this formula, after the desired torque is calculated in step S6 in the flight motion control, the desired torque can be brought into the left side of the equation, and the desired rotation speed of the upper motor 3 and the lower motor 5 and the desired rotation angle of the four steering gears 12 can be calculated by matrix pseudo-inverse operation and other methods, so as to achieve fast and accurate control amount distribution;

[0040] Furthermore, through the force analysis of the UAV, the dynamic model of the ground motion can be obtained as follows:

[0041]

[0042] Among them, a x_g , a y_g is the component of the ground desired acceleration in the x and y axis directions in the plane coordinate system, k δx is the force efficiency parameter of the aerodynamic force of the control surface in the x-axis direction of the fuselage coordinate system, k δyis the force effect parameter of the aerodynamic force of the rudder surface in the y-axis direction of the fuselage coordinate system, the rudder surface model parameter, m is the total mass of the fuselage of the UAV, and δ1~δ4 are the rotation angles of the four servos 12. Through this dynamic model, after the expected acceleration is calculated in step T2 in the ground sliding motion control, the expected acceleration can be brought into the left side of the equation, and the expected rotation angle of the four servos 12 that can be executed by the bottom controller can be calculated through matrix pseudo-inverse operation to achieve fast and accurate control quantity distribution.

[0043] Compared with the prior art, the present invention has the following advantages and effects:

[0044] (1) The present invention proposes an improved design of a coaxial twin-rotor ducted UAV, which adds universal wheels to the bottom of the fuselage and uses the rudder of the ducted UAV to deflect the high-speed airflow at the duct outlet to obtain propulsion to achieve controllable ground movement. Compared with the high-speed rotation of the rotor to generate lift to overcome its own gravity during flight, when gliding on the ground, the UAV only needs to rotate the rotor at a low speed to generate accelerated airflow, use the rudder to deflect the airflow to generate propulsion, and the universal wheels overcome the friction under the action of the propulsion to glide on the ground. The power required is about 20% of that during flight. With this structural improvement,

[0045] (2) The present invention also proposes a set of amphibious motion control methods. By conducting dynamic analysis and modeling on both ground and air motion modes, an effective control scheme is designed. Experiments have verified that the present invention has the ability to move both on the ground and in the air, and the designed control scheme has achieved a relatively ideal control effect. Experimental verification shows that by combining ground motion, the drone of the present invention can obtain an operating time that is about 5 times longer than the flight mode, thereby greatly improving the drone's endurance time and operating range.

[0046] (3) The present invention realizes the use of the same power system for both ground and air movement through structural improvement and coordinated design of control scheme, without the need for additional drive mechanisms. At the same time, the mechanical mechanism is simplified, thereby reducing the overall weight of the UAV and reducing the structural complexity. In addition, the main structural parts of the fuselage are all integrally formed by 3D printing, which has the advantage of being easy to produce and manufacture.

[0047] (3) Since the present invention adopts a design in which the rotor is wrapped by a ducted shell, all moving parts including the rotor and servo are located inside the ducted shell and the base. When the UAV is running, the high-speed rotating blades will not cause damage to the external environment and can safely contact the environment and people. It has a safety advantage and is particularly suitable for indoor spaces and spaces with dense and complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0049] Figure 1 It is a ground motion schematic diagram of a land-air amphibious coaxial twin-rotor ducted UAV disclosed in the present invention;

[0050] Figure 2 It is a schematic diagram of the aerial movement of a land-air amphibious coaxial twin-rotor ducted UAV disclosed in the present invention;

[0051] Figure 3 This is a structural disassembly diagram of a land-air amphibious coaxial twin-rotor ducted UAV disclosed in the present invention;

[0052] Figure 4 It is an overall schematic diagram of a land-air amphibious coaxial twin-rotor ducted UAV disclosed in the present invention;

[0053] Figure 5 Schematic diagram of the duct shell parts of the UAV in the present invention, wherein: Figure 5 (a) is the top view of the duct shell. Figure 5 (b) is an isometric view of the duct shell;

[0054] Figure 6 Schematic diagram of the duct base parts of the UAV in the present invention, wherein: Figure 6 (a) is a top view of the duct base. Figure 6 (b) is an isometric view of the duct base;

[0055] Figure 7 This is an experimental verification diagram of a land-air amphibious coaxial twin-rotor ducted UAV disclosed in the present invention, wherein: Figure 7 (a) is the flight control experiment diagram. Figure 7 (b) is the ground motion control experiment diagram;

[0056] Figure 8 It is a flight experiment position data diagram of a land-air amphibious coaxial twin-rotor ducted UAV disclosed in the present invention;

[0057] Fig. 9 It is a flight experiment speed tracking data diagram of a land-air amphibious coaxial twin-rotor ducted UAV disclosed in the present invention;

[0058] Fig.10 It is a ground motion experimental position data diagram of a land-air amphibious coaxial twin-rotor ducted UAV disclosed in the present invention;

[0059] Fig.11It is a velocity tracking data diagram of a ground motion experiment of a land-air amphibious coaxial twin-rotor ducted UAV disclosed in the present invention;

[0060] Among them, the markings in the accompanying drawings are as follows: 1---duct housing, 2---duct base, 3---upper motor, 4---upper rotor, 5---lower motor, 6---lower rotor, 7---battery, 8---control circuit, 9---top shell, 10---universal wheel, 11---rudder surface, 12---servo. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] Example 1

[0063] like Figure 3 , Figure 4 and Figure 7 As shown, this embodiment discloses a specific structure of an amphibious coaxial twin-rotor ducted UAV, the UAV includes a fuselage structure, a power device, an aerodynamic regulating device, a control computing device and a battery.

[0064] The fuselage structure of the UAV includes a duct shell 1, a duct base 2, three universal wheels 10, and a top shell (10). The duct shell 1 is a cylindrical shell structure, and is connected and fixed to the duct base 2 by screws through four groups of threaded holes evenly distributed on the duct shell 1. The lower side of the duct base 2 has three groups of protrusions as a support frame, and a threaded hole is provided at the lower end of the support frame. The three universal wheels 10 all have threaded columns, which are connected and fixed to the threaded holes at the lower end of the support frame of the duct base 2. The top shell 9 is installed at the top center position of the duct shell 1 by screws.

[0065] The above-mentioned fuselage structure serves as the fuselage and main load-bearing component of the UAV, provides an installation location for the power unit, aerodynamic regulation device, and control computing device, and structurally provides hardware for flight and ground gliding.

[0066] The power device includes an upper motor 3, an upper rotor 4, a lower motor 5, and a lower rotor 6. The upper motor 3 has a base mounting hole, which is fixedly connected to the upper central position of the duct shell 1 by screws. The upper rotor 4 has a central threaded hole, which is fixedly connected to the central stud of the upper motor 3 by nuts, and rotates with the upper motor 3. The lower motor 5 has a base mounting hole, which is fixedly connected to the central position of the top of the duct base 2 by screws and is located inside the duct shell 1. The lower rotor 6 has a central threaded hole, which is fixedly connected to the central stud of the lower motor 5 by nuts, and rotates with the lower motor 5. The upper rotor 4 and the lower rotor (5) have a rotor airfoil, which accelerates the air flow by rapid rotation, generates lift on the rotor by using the Bernoulli principle, and causes the accelerated airflow to be ejected at high speed from the outlet of the duct base 2, providing the main power for the movement of the drone. The motor model used in this embodiment is iFlight XING 1100KV 2814, and motors of similar size can also be used in specific implementations.

[0067] The aerodynamic force regulating device comprises four servos 12 and four control surfaces 11, wherein the four servos 12 all have mounting holes, are fixed horizontally to the lower center of the duct base 2 by screws and are arranged in a uniform circle, the rotation axes of the four servos 12 face the outside of the duct base 2, and the four control surfaces 11 are fixedly connected to each other in pairs by screws through the mounting holes on their inner sides, and are rotated by the drive of the four servos 12; the four control surfaces 11 have airfoils, and when the upper rotor 4 and the lower rotor 6 rotate at high speed to generate airflow that is ejected at high speed through the inner outlet of the duct base 2, the four control surfaces 11 deflect to make the gas flow rates on both sides of the airfoil different, and the Bernoulli principle is used to generate aerodynamic force on the four control surfaces 11, thereby controlling and regulating the movement posture of the UAV during flight and the speed during ground movement. In a specific implementation, the number of servos at the bottom can be 2 servos and 2 rudder surfaces, 4 groups of servos and 4 rudder surfaces (used in this embodiment), or 6 servos and 6 rudder surfaces, which can be achieved by modifying the duct base 2.

[0068] The control computing device includes a control circuit 8, which is installed at the top center of the duct shell 1 through a plastic stud, and the top shell 9 is located inside the top shell 9. The control circuit receives remote control signals and has attitude and speed sensors. It performs motion control through codes, calculates the rotation speed of the upper motor 3 and the lower motor 5 and the rotation angle of the four steering gears 12, and sends them to the corresponding upper motor 3, the lower motor 5 and the four steering gears 12 through data connection lines, thereby realizing the motion control of the drone;

[0069] The battery 7 is inserted from the top inner opening of the duct shell 1 and fixed on the UAV, and is connected to the control circuit 8, the upper motor 3, the lower motor 5 and the four servos 12 through a power line to provide power for these devices.

[0070] like Figure 5As shown in (a) and 5(b), the duct shell 1 is a through cylindrical duct cavity, and the top opening of the cavity has an outward-expanded aerodynamic airfoil, which has the function of increasing the lift of the duct. The top opening of the cavity is provided with eight hollow pillars evenly distributed in a circle. In a specific implementation, the number of the hollow pillars can be 4 groups, 6 groups, or 8 groups (used in this embodiment), which have the function of bearing force. The eight pillars are connected to the structural compartment on the upper side of the duct shell. The upper side of the structural compartment is provided with an organic top shell 9, and the structural compartment is provided with a cavity and a fixed hole position. The battery 7 and the control circuit 8 are fixedly installed in the cavity. The upper motor 3 is installed and connected to the duct shell 1 through the fixed hole position. The outer surface of the duct cavity has four evenly distributed rectangular depressions on the basis of the cylindrical shell, and the protruding part between the depressions has four groups of threaded holes near the lower end surface. This design has the function of reducing the weight of the structure and has the function of connecting the duct base 2. The duct shell 1 is formed in one piece by 3D printing, which has the function of rapid production and reducing the weight of the structure.

[0071] like Figure 6 As shown in (a) and 6(b), the duct base 2 has an inner and outer ring cylindrical shell structure and a cross beam structure connecting the inner and outer rings, wherein the outer ring cylindrical shell has protrusions at intervals of 120° on the lower side, and a threaded hole is provided at the center of the lower end face of the protrusion. The protrusion has the function of providing support for the drone, and the threaded hole on the lower end face has the function of facilitating the installation of universal wheels. The outer ring cylindrical shell has four groups of rectangular protrusions distributed at intervals of 90° on the outside, and the central positions of these protrusions have mounting holes, which cooperate with the mounting holes on the lower side of the duct shell 1 to connect the two.

[0072] Four sets of steering gear fixing platforms are arranged at the bottom of the lower end surface of the inner cylindrical shell. Each set of fixing platforms has two rectangular protrusions and a threaded hole in the center of the rectangle for installing and fixing four steering gears 12.

[0073] The outer end of the cross-shaped beam structure is connected to the outer ring cylindrical shell, and the inner end crosses and intersects with the inner ring cylindrical shell. The interior of the cross-shaped beam structure is a cavity, which serves to reduce the weight of the structure. The central intersection of the cross-shaped beam structure has a sunken design and is provided with four groups of mounting holes distributed at 90° intervals for fixing the lower motor 5. An aerodynamic force adjustment device is provided above the cross-shaped beam structure to reduce air resistance.

[0074] Example 2

[0075] like Figure 1 and Figure 2 As shown, based on the land-air amphibious coaxial twin-rotor ducted UAV disclosed in Example 1, this embodiment further discloses an air motion control method of the land-air amphibious coaxial twin-rotor ducted UAV, and conducts a motion experiment. The air motion control method includes the following steps:

[0076] S1, the control calculation device receives the flight speed instruction and collects the speed feedback value of the drone through the speed sensor on the control circuit 8;

[0077] S2, the control calculation device calculates the difference between the flight speed command and the UAV speed feedback value, and multiplies it by the air speed gain coefficient, and the obtained value is recorded as the first expected acceleration;

[0078] S3, the control calculation device calculates the expected attitude and expected lift of the UAV from the first expected acceleration through the kinematic model of the attitude and lift of the UAV;

[0079] S4, the control calculation device collects the attitude feedback value of the UAV through the attitude sensor on the control circuit 8;

[0080] S5. The control calculation device calculates the difference between the desired attitude and the attitude feedback value, and multiplies it by the air attitude gain coefficient, and the obtained value is recorded as the desired torque;

[0081] S6, the control calculation device calculates the expected rotation speeds of the upper motor 3 and the lower motor 5 and the expected rotation angles of the four steering gears 12 according to the expected torque through the dynamic model of the UAV, and sends the calculation results to the corresponding upper motor 3, the lower motor 5 and the four steering gears 12 through the data transmission line;

[0082] S7, return to step S1, continue to receive flight speed instructions and collect speed feedback values, and calculate the speed of the upper motor 3, the lower motor 5 and the rotation angle of the four steering gears 12 in real time, realize the control of flight motion until the flight mission is completed, and stop calculating; In this embodiment, when controlling the flight motion in the air, the kinematic model of the UAV attitude and lift is

[0083]

[0084]

[0085]

[0086] in, is the roll angle, θ is the pitch angle, T is the lift of the drone, a x ,a y ,a z They are the three-axis accelerations in the UAV body coordinate system;

[0087] The dynamic model of the UAV is:

[0088]

[0089]

[0090] Among them, kF1 is the lift coefficient of the upper motor 3, k F2 is the lift coefficient of the lower motor 5, k vane is the aerodynamic coefficient of the rudder surface, k M1 is the torque coefficient of the upper motor 3, k M2 is the torque coefficient of the lower motor 5, l1 is the projection distance from the aerodynamic center of the rudder surface to the center of gravity of the fuselage on the x-axis in the body coordinate system, l2 is the projection distance from the aerodynamic center of the rudder surface to the center of gravity of the fuselage on the z-axis in the body coordinate system, V e is the wind speed at the duct outlet, Ω1 and Ω2 are the rotation speeds of the upper motor 3 and the lower motor 5, δ1 to δ4 are the rotation angles of the four steering gears 12, M = {M x M y M z} T is the three-axis moment in the fuselage coordinate system. There may be multiple calculation methods to solve this equation. In order to facilitate calculation and control distribution, in this embodiment, the influence of the rudder deflection on the heading angle is ignored and the model is simplified as follows:

[0091]

[0092]

[0093] Through the matrix pseudo-inverse operation, we can get:

[0094]

[0095] Through this formula, after the desired torque is calculated in step S6 in the flight motion control, the desired torque can be substituted into the right side of the equation to obtain the desired rotation speed of the upper motor 3 and the lower motor 5 and the desired rotation angle of the four steering gears 12, thereby realizing fast and accurate control amount distribution;

[0096] The control method of aerial motion is experimentally verified. Given the desired position of aerial motion as a figure-8 trajectory with a length of 4 meters and a width of 2 meters and a constant height, the flight of the drone in the air is shown in the attached figure. Figure 7 (a) The experimental data can be found in Figure 8 and Fig. 9 , Fig. 9 It reflects the speed tracking during the flight. The given speed changes within about ±0.5m / s, and the drone can quickly track the given speed command, with the error kept within a small range (0.1m / s). Figure 8Reflecting the position tracking of the drone during flight, the three-dimensional root mean square error (RMSE) of tracking in space is only 0.1908m, and the given "8"-shaped trajectory can basically maintain good tracking. The experiment shows that the drone has the ability to fly, and the ideal air motion control accuracy is achieved according to the air motion control method in Example 2.

[0097] Example 3

[0098] like Figure 1 and Figure 2 As shown, based on the land-air amphibious coaxial twin-rotor ducted UAV disclosed in Example 1, this embodiment further discloses a ground sliding control method of the land-air amphibious coaxial twin-rotor ducted UAV, and conducts a motion experiment. The ground sliding control method includes the following steps:

[0099] T1, the control calculation device receives the sliding speed instruction when moving on the ground, and collects the speed feedback value of the drone through the speed sensor on the control circuit 8;

[0100] T2, the control calculation device calculates the difference between the sliding speed command and the UAV speed feedback value, and multiplies it by the ground speed gain coefficient, and the obtained value is recorded as the second expected acceleration;

[0101] T3, the control calculation device sets the rotation speed of the upper motor 3 and the lower motor 5 to a fixed value through the dynamic model of ground motion, calculates the expected rotation angle of the four steering gears 12 according to the second expected acceleration, and sends the calculation result to the upper motor 3, the lower motor 5 and the four steering gears 12 through the data transmission line;

[0102] T4, return to step T1, continue to receive the sliding speed command and collect the speed feedback value, and calculate the rotation speed of the upper motor 3, the lower motor 5 and the rotation angle of the four servos 12 in real time to realize the control of the UAV's ground sliding until the movement task is completed, and stop the calculation.

[0103] In this embodiment, when controlling the ground sliding motion, the dynamic model of the ground motion is:

[0104]

[0105] Among them, a x_g , a y_g is the component of the ground desired acceleration in the x and y axis directions in the plane coordinate system, k δx is the force efficiency parameter of the aerodynamic force of the control surface in the x-axis direction of the fuselage coordinate system, k δyis the force efficiency parameter of the aerodynamic force of the rudder surface in the y-axis direction of the fuselage coordinate system, the rudder surface model parameter, m is the total mass of the fuselage of the UAV, and δ1~δ4 are the rotation angles of the four servos 12. There may be multiple calculation methods for solving this equation. In order to facilitate calculation and control allocation, in this embodiment, the following is obtained through matrix pseudo-inverse operation:

[0106]

[0107] Through this model, after the expected acceleration is calculated in step T2 in the ground sliding motion control, the expected acceleration can be substituted into the right side of the equation, and the expected turning angle of the four servos 12 that can be executed by the underlying controller can be calculated through matrix pseudo-inverse operation.

[0108] The control method of ground sliding is experimentally verified. Given the expected position of ground motion as an "8"-shaped trajectory with a length of 4 meters and a width of 2 meters, the motion trajectory of the UAV on the ground is shown in the attached figure. Figure 7 (b), the experimental data are shown in Fig.10 and Fig.11 ,Combined with the experimental data, it can be seen that the UAV can quickly track the given speed instruction, and the error is kept within a small range, Fig.11 It reflects the speed tracking during ground movement. The given speed changes within about ±0.2m / s, and the UAV can quickly track the given speed command, with the error kept within a small range (0.05m / s). Fig.10 The position tracking of the UAV's ground motion is reflected in the two-dimensional root mean square error (RMSE) of plane tracking is only 0.0896m. For a given "8"-shaped trajectory, it can basically maintain good tracking. The experiment shows that the UAV has the ability to move on the ground, and the control method of ground sliding in Example 3 achieves ideal ground motion control accuracy.

[0109] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A land-air amphibious coaxial twin-rotor ducted UAV, characterized in that: The unmanned aerial vehicle comprises a fuselage structure, a power device, an aerodynamic force regulating device, a control computing device and a battery (7). The fuselage structure comprises a duct shell (1), a duct base (2), three universal wheels (10), and a top shell (9). The duct shell (1) is a cylindrical shell structure, and is connected and fixed to the duct base (2) by screws through four groups of threaded holes evenly distributed on the duct shell (1). The lower side of the duct base (2) has three groups of protrusions as a support frame, and the lower end of the support frame has a threaded hole. The three universal wheels (10) all have a threaded column, which is connected and fixed to the threaded hole at the lower end of the support frame of the duct base (2). The top shell (9) is installed at the central position of the top of the duct shell (1) by screws. The power device comprises an upper motor (3), an upper rotor (4), a lower motor (5), and a lower rotor (6); the upper motor (3) has a base mounting hole, and is fixedly connected to the upper central position of the duct shell (1) by screws; the upper rotor (4) has a central threaded hole, and is fixedly connected to the central stud of the upper motor (3) by nuts, and rotates with the upper motor (3); the lower motor (5) has a base mounting hole, and is fixedly connected to the central position of the top of the duct base (2) by screws, and is located inside the duct shell (1); the lower rotor (6) has a central threaded hole, and is fixedly connected to the central stud of the lower motor (5) by nuts, and rotates with the lower motor (5); the upper rotor (4) and the lower rotor (6) have rotor airfoils, and accelerate air flow by rapid rotation, generate lift on the rotor by using the Bernoulli principle, and cause the accelerated airflow to be ejected at high speed from the outlet of the duct base (2); The aerodynamic force regulating device comprises four steering gears (12) and four control surfaces (11), wherein the four steering gears (12) all have mounting holes, are fixed horizontally to the center of the lower side of the duct base (2) by screws and are arranged in a uniform circumference, the rotation axes of the four steering gears (12) face the outside of the duct base (2), and the four control surfaces (11) are fixedly connected to the four steering gears (12) in pairs by screws through the mounting holes on the inner side of the four steering gears (11), and are rotated by the drive of the four steering gears (12); the four control surfaces (11) have airfoils, and when the upper rotor (4) and the lower rotor (6) rotate at high speed to generate airflow that is ejected at high speed through the inner outlet of the duct base (2), the four control surfaces (11) deflect to make the gas flow rates on both sides of the airfoil different, and the Bernoulli principle is used to generate aerodynamic forces on the four control surfaces (11), thereby controlling and regulating the motion posture of the UAV during flight and the speed of the UAV during ground movement; The control calculation device comprises a control circuit (8), which is installed at the top center of the duct shell (1) through a plastic stud and is located inside the top shell (9). The control circuit receives remote control signals and has attitude and speed sensors. It performs motion control through codes, calculates the rotation speeds of the upper motor (3) and the lower motor (5) and the rotation angles of the four steering gears (12), and sends the corresponding data to the upper motor (3), the lower motor (5) and the four steering gears (12) through data connection lines, thereby realizing the motion control of the UAV. The battery (7) is inserted through the top inner opening of the duct shell (1) and fixed on the drone, and is connected to the control circuit (8), the upper motor (3), the lower motor (5) and the four steering gears (12) via power lines.

2. The land-air amphibious coaxial twin-rotor ducted UAV according to claim 1, characterized in that: The duct shell (1) is a through cylindrical duct cavity, and the top opening of the cavity has an outward-expanding aerodynamic airfoil, which has the function of increasing the duct lift. The top opening of the cavity is provided with eight hollow pillars evenly distributed in a circumference, and the eight hollow pillars are connected to the structural compartment on the upper side of the duct shell (1). An organic top shell (9) is provided on the upper side of the structural compartment, and the structural compartment is provided with a cavity and a fixing hole. The battery (7) is fixedly installed in the cavity, and the upper motor (3) is installed and connected to the duct shell (1) through the fixing hole.

3. The amphibious coaxial twin-rotor ducted UAV according to claim 1, characterized in that: The control circuit (8) is fixed on the top of the top shell (9).

4. The amphibious coaxial twin-rotor ducted UAV according to claim 1, characterized in that: The duct base (2) has an inner and outer cylindrical shell structure and a cross beam structure connecting the inner and outer rings, wherein the outer cylindrical shell has protrusions at intervals of 120 degrees on the lower side, and a threaded hole is provided at the center of the lower end surface of the protrusion; Four sets of steering gear fixing platforms are arranged at the bottom of the lower end surface of the inner cylindrical shell. Each of the four fixing platforms has two rectangular protrusions and a threaded hole in the center of the rectangle, which are used to respectively install and fix four steering gears (12); the outer end of the cross-shaped beam structure is connected to the outer cylindrical shell, and the inner end crosses and intersects with the inner cylindrical shell. The interior of the cross-shaped beam structure is a cavity. The central intersection of the cross-shaped beam structure has a sunken design and is provided with four sets of mounting holes distributed at 90° intervals, which are used to install the lower motor (5). An aerodynamic force adjustment device is arranged below the cross-shaped beam structure.

5. A motion control method for an amphibious coaxial twin-rotor ducted UAV according to any one of claims 1 to 4, characterized in that: The motion control method includes air flight motion control and ground sliding motion control, wherein the air flight motion control includes the following steps: S1, the control calculation device receives the flight speed instruction and collects the speed feedback value of the UAV through the speed sensor on the control circuit (8); S2, the control calculation device calculates the difference between the flight speed command and the UAV speed feedback value, and multiplies it by the air speed gain coefficient, and the obtained value is recorded as the air expected acceleration; S3, the control calculation device calculates the expected attitude and expected lift of the UAV from the expected acceleration in the air through the kinematic model of the attitude and lift of the UAV; S4, the control calculation device collects the attitude feedback value of the UAV through the attitude sensor on the control circuit (8); S5. The control calculation device calculates the difference between the desired attitude and the attitude feedback value, and multiplies it by the air attitude gain coefficient, and the obtained value is recorded as the desired torque; S6, the control calculation device calculates the expected rotation speeds of the upper motor (3) and the lower motor (5) and the expected rotation angles of the four steering gears (12) from the expected torque through the dynamic model of the unmanned aerial vehicle, and sends the calculation results to the corresponding upper motor (3), the lower motor (5) and the four steering gears (12) through the data transmission line; S7, return to step S1, continue to receive the flight speed command and collect the speed feedback value, and calculate the rotation speed of the upper motor (3), the lower motor (5) and the rotation angle of the four steering gears (12) in real time, realize the control of the flight movement until the flight mission is completed, and stop the calculation; Wherein, the ground sliding motion control comprises the following steps: T1, the control calculation device receives the sliding speed instruction when moving on the ground, and collects the speed feedback value of the drone through the speed sensor on the control circuit (8); T2, the control calculation device calculates the difference between the sliding speed command and the UAV speed feedback value, and multiplies it by the ground speed gain coefficient, and the obtained value is recorded as the ground expected acceleration; T3, the control calculation device sets the rotation speed of the upper motor (3) and the lower motor (5) to a fixed value through the dynamic model of ground motion, calculates the expected rotation angle of the four steering gears (12) based on the expected ground acceleration, and sends the calculation results to the upper motor (3), the lower motor (5) and the four steering gears (12) through the data transmission line; T4, return to step T1, continue to receive the sliding speed command and collect the speed feedback value, and calculate the rotation speed of the upper motor (3), the lower motor (5) and the rotation angle of the four steering gears (12) in real time, realize the control of the ground sliding of the UAV until the movement task is completed, and stop the calculation.

6. The motion control method according to claim 5, characterized in that: In the aerial flight motion control, the kinematic model of the UAV attitude and lift is: in, is the roll angle, θ is the pitch angle, T is the lift of the drone, a x ,a y ,a z They are the three-axis accelerations in the UAV body coordinate system; The dynamic model of the UAV is: Among them, k F1 is the lift coefficient of the upper motor (3), k F2 is the lift coefficient of the lower motor (5), k vane is the aerodynamic coefficient of the rudder surface, k M1 is the torque coefficient of the upper motor (3), k M2 is the torque coefficient of the lower motor (5), l1 is the projection distance from the aerodynamic center of the rudder surface to the center of gravity of the fuselage on the x-axis in the body coordinate system, l2 is the projection distance from the aerodynamic center of the rudder surface to the center of gravity of the fuselage on the z-axis in the body coordinate system, V e is the wind speed at the duct outlet, Ω1 and Ω2 are the rotation speeds of the upper motor (3) and the lower motor (5) respectively, δ1-δ4 are the rotation angles of the four steering gears (12) respectively, and M is the three-axis torque in the fuselage coordinate system.

7. The motion control method according to claim 5, characterized in that: In the control of ground sliding motion, the dynamic model of ground motion is: Among them, a x_g , a y_g is the component of the ground desired acceleration in the x and y axis directions in the plane coordinate system, k δx is the force efficiency parameter of the aerodynamic force of the control surface in the x-axis direction of the fuselage coordinate system, k δy is the force efficiency parameter of the aerodynamic force of the rudder surface in the y-axis direction of the fuselage coordinate system, is the rudder surface model parameter, m is the total mass of the fuselage of the UAV, and δ1~δ4 are the rotation angles of the four servos (12) respectively.

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