Distributed power fixed-point take-off and landing portable solar unmanned aerial vehicle

Abstract

The invention discloses a distributed power fixed-point take-off and landing portable solar unmanned aerial vehicle, and belongs to the technical field of overall comprehensive design of unmanned aerial vehicles. Comprising a front wing, a rear wing and a folding assembly, the front wing and the rear wing are arranged in a tandem wing mode, the folding assembly is connected between the front wing and the rear wing, the front edge of the front wing and the front edge of the rear wing are each provided with a plurality of rotors in the spanwise direction, and the four rotors located in the spanwise middle of the front wing and the spanwise middle of the rear wing are located at the four vertexes of a quadrangle respectively to form the four-rotor power system of the unmanned aerial vehicle. The other rotor wings form a fixed wing power system of the unmanned aerial vehicle; the front wing and the rear wing are connected into a tandem wing with a space height difference through the folding assembly, and the front wing and the rear wing can be in a stacked state through deformation. The problems that a single-type propeller of a tailstock type configuration machine consumes much energy, the efficiency of the cruising stage is low, and the endurance is short are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of overall integrated design of unmanned aerial vehicles, and in particular relates to a distributed power fixed-point take-off and landing portable solar-powered unmanned aerial vehicle. Background Art

[0002] The Qinghai-Tibet Plateau is vast and sparsely populated, with thin air, low pressure and lack of oxygen. The rangers' activity areas and work efficiency are mostly limited. UAV technology provides a possibility to reduce the workload of rangers. The existing research on quadcopters is relatively mature, but their flight time and range are short, which makes it difficult to meet the needs of rangers, scientific research and other work. Therefore, fixed-wing solar-powered drones are needed.

[0003] At present, most solar-powered drones used for plateau ecological monitoring adopt a large aspect ratio design. They are large in size, not easy to carry, and require assembly, which cannot meet the requirements of single-person use. In addition, most existing solar-powered drones take off and land by taxi, and it is difficult to find a suitable take-off and landing site in the wild. Due to the restrictions on take-off and landing conditions, it is necessary to design a portable solar-powered drone with the ability to take off and land at a fixed point.

[0004] According to the overall configuration and power form, the current mainstream fixed-point take-off and landing fixed-wing UAVs can be divided into three configurations: lift-thrust composite type, tilt-rotation power type, and tail-seat type. The rotor of the lift-thrust composite configuration UAV used to provide vertical lift loses its function during the cruising stage after takeoff, becoming a burden on the aircraft's flight and not meeting the portability requirements; the tilt-rotation mechanism of the tilt-rotation power configuration UAV occupies a large weight quota, which increases the weight of the entire machine; the tail-seat configuration is compact and light, and flexible to control. The tail-seat solar UAV disclosed in the prior art adopts a large aspect ratio flying wing layout, and switches the operating mode through ailerons and pitch-shifting propellers with automatic tilters. However, it has the problem of low efficiency and short flight time in the cruising stage due to a single type of propeller, and it still adopts a large aspect ratio design, which does not solve the problem of poor portability and being greatly affected by gusts of wind in existing solar UAVs. Distributed power systems and tandem wing configurations provide ideas for solving the above problems.

[0005] The problems of existing solar-powered drones for plateau ecological monitoring are as follows:

[0006] (1) The existing solar-powered drones for plateau ecological monitoring are large in size, need to be disassembled and assembled, have poor portability, and cannot meet the requirements of single-person use.

[0007] (2) Most of the existing solar-powered drones for plateau ecological monitoring take off and land on a taxiing platform, which are highly dependent on the site and auxiliary equipment.

[0008] (3) The existing solar-powered UAVs for plateau ecological monitoring that can take off and land at a fixed point have inherent disadvantages due to their lift-thrust, tilt-rotation, and tail-seat configurations.

[0009] (4) Most of the existing solar-powered drones for plateau ecological monitoring that can take off and land at a fixed point adopt vertical take-off and landing. The vertical take-off method can only provide the drone with vertical acceleration, resulting in a certain amount of energy waste. Summary of the invention

[0010] Technical issues to be solved:

[0011] In order to avoid the shortcomings of the prior art, the present invention provides a distributed power fixed-point take-off and landing portable solar-powered UAV, which adopts a tandem wing layout, and the front and rear wings can be stacked by a folding assembly. The multi-rotor layout design constitutes a distributed power system combining a fixed-wing mode and a four-rotor mode, which solves the problems of a single type of propeller consuming a lot of energy in a tail-seat configuration aircraft, low efficiency in the cruising phase, and short flight time. Moreover, the tandem wing layout distributes the center of gravity between the front and rear wings, which helps to maintain the balance of the UAV when affected by gusts during the take-off and landing phases, thereby improving the problem that the tail-seat configuration aircraft is greatly affected by gusts.

[0012] The technical solution of the present invention is: a distributed power fixed-point take-off and landing portable solar-powered UAV, comprising a front wing and a rear wing arranged in a tandem wing form and a folding assembly connected therebetween, wherein the leading edges of the front wing and the rear wing are each provided with a plurality of rotors along the span direction, and the four rotors located in the middle of the front wing and the rear wing in the span direction are respectively located at the four vertices of a quadrilateral, forming a four-rotor power system of the UAV, and the remaining rotors form a fixed-wing power system of the UAV; the folding assembly connects the front wing and the rear wing into a tandem wing with a spatial height difference, and the front wing and the rear wing can be stacked by deformation.

[0013] A further technical solution of the present invention is: the spatial height difference between the front wing and the rear wing is 0.32 meters to 0.38 meters; the aspect ratio of the front wing is 3.9-4.2; and the aspect ratio of the rear wing is 3.8-4.0.

[0014] A further technical solution of the present invention is: the front wing and the rear wing serve as the main lifting surfaces, and the upper surfaces thereof are evenly covered with solar panels. Four rotors are arranged along the span direction of the leading edges thereof, and the eight rotors are respectively located at the vertices of the inner and outer quadrilaterals. The four rotors located in the inner ring are symmetrically installed on the leading edges of the middle parts of the front and rear wings of the UAV along the middle symmetry plane of the UAV, so as to provide lift during the take-off and landing stages, and control the flight attitude of the UAV by means of power differential; the four rotors located in the outer ring are symmetrically installed on the leading edges of the wingtips of the front and rear wings of the UAV along the middle symmetry plane of the UAV, so as to provide thrust during the fixed-wing cruise stage, and resist wind by means of power differential during the take-off and landing stages.

[0015] A further technical solution of the present invention is: when the UAV is in a vertical landing state, the four rotors of the inner ring form a square in a top view, and the center of gravity of the UAV is located at the center of the square.

[0016] A further technical solution of the present invention is: vertical tail wings are respectively installed at the two end portions of the rear wing, and the two vertical tail wings are symmetrically distributed along the middle symmetry plane of the UAV; and elevator ailerons are symmetrically hinged at the trailing edges of the two ends of the rear wing.

[0017] A further technical solution of the present invention is: the folding component includes two front and rear wing connecting rods symmetrically distributed on the middle symmetry plane of the drone, one end of the front and rear wing connecting rod is connected to the front wing, and the other end is connected to the rear wing, and two centrally symmetrically installed aluminum alloy transverse folding parts are arranged in the middle section, so that the two ends of the front and rear wing connecting rods can be folded in reverse, and the front and rear wing connecting rods are in a Z shape after folding.

[0018] A further technical solution of the present invention is: a transverse connecting rod is vertically installed between the two front and rear wing connecting rods, the center of gravity of the UAV is located in the middle of the transverse connecting rod, and a battery compartment is installed at its center position, and a battery is installed in the battery compartment to provide energy for the flight of the UAV.

[0019] A further technical solution of the present invention is: the rotor includes a motor and a propeller installed at the output end thereof, and the rotation speed of the motor is controlled by an electronic speed regulator to drive the propeller to rotate.

[0020] A further technical solution of the present invention is: the UAV also includes a navigation system, a flight control system, a measurement and control system, airborne cables and a payload compartment; the payload compartment is located in the middle of the leading edge of the front wing, and the navigation system, the flight control system, and the measurement and control system are installed therein, and the airborne cables are distributed inside the front and rear wings and on the surface of each connecting rod.

[0021] A take-off support frame for a distributed power fixed-point take-off and landing portable solar-powered UAV comprises a front tiltable support member and a rear fixed support member, which determine the take-off angle of the UAV to be 45°; the tiltable support member is used to support the front wing of the UAV, and the tiltable support member tilts forward at the moment of take-off; the rear fixed support member is used to support the rear wing of the UAV.

[0022] Beneficial Effects

[0023] The beneficial effects of the present invention are:

[0024] (1) The present invention can achieve fixed-point takeoff and landing and fixed-wing cruise. Most existing solar-powered drones take off and land by taxiing, and cannot achieve vertical takeoff and landing and hover in the air, and are restricted by the environment when in use. The present invention adopts a distributed power system, which divides the power device of the entire aircraft into an inner ring mainly responsible for fixed-point takeoff and landing, and an outer ring mainly responsible for fixed-wing cruise, thereby achieving large-angle fixed-point takeoff and four-rotor mode landing of fixed-wing aircraft, greatly reducing the requirements for the take-off and landing environment. Compared with four-rotor drones that can take off and land vertically, the present invention increases the flight time and range of the drone.

[0025] (2) The present invention has good portability and can meet the requirements of single-person control and use. The tandem wing layout is adopted to ensure sufficient wing area for laying solar panels while reducing the aspect ratio of the wing; the connecting rod connecting the front and rear wings of the drone is designed to be foldable, and the folding function is achieved by an aluminum alloy transverse folding piece installed on the connecting rod, thereby ensuring the structural integration of the drone while further reducing the size of the drone. The combination of the tandem wing layout and the foldable method greatly reduces the size of the drone, and its folded size can meet the requirements of single-person carrying; at the same time, the present invention adopts a folding integrated design, which does not require disassembly and assembly, is easy to use, and has a low cost of use.

[0026] (3) The present invention has high propulsion efficiency and no thrust redundancy. By adopting a distributed power system with inner and outer rings, the main power device of the UAV in each flight stage is within its range of high working efficiency, thereby improving the propulsion efficiency; the secondary power device of the UAV in each flight stage increases the control amount through differential control, and plays a role in wind resistance, etc., and each power device is fully utilized. At the same time, the additional weight increase caused by the lift-thrust compound type and the tilt-rotation power type is avoided, and the center of gravity is distributed between the front and rear wings through the tandem wing layout, which helps to maintain the balance of the UAV when affected by gusts during take-off and landing, and improves the problem that the tail-seat configuration aircraft is greatly affected by gusts.

[0027] (4) The present invention adopts the autonomous visual guidance landing method of the quad-rotor mode UAV, which improves the landing accuracy. After the landing command is issued, the UAV switches from the fixed-wing cruise mode to the quad-rotor mode to ensure the stability during the vertical landing process, and combines the autonomous visual guidance method of the UAV to achieve accurate landing at the target point.

[0028] (5) The present invention adopts a large-angle fixed-point take-off method, which provides lift for the UAV while also providing a certain horizontal thrust, so that the effective lift provided by the wing can meet the flight requirements as early as possible, reducing the energy consumption during the take-off phase. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is an overall schematic diagram of the present invention in a level flight state;

[0030] Figure 2 It is a front view of the present invention in a level flight state;

[0031] Figure 3 It is a top view of the present invention in a level flight state;

[0032] Figure 4 It is a side view of the present invention in a level flight state;

[0033] Figure 5 It is an overall schematic diagram of the present invention in a folded state;

[0034] Figure 6 It is a front view of the present invention in a folded state;

[0035] Figure 7 A top view of the present invention in a folded state;

[0036] Figure 8 A side view of the present invention in a folded state;

[0037] Fig. 9 It is a schematic diagram of the overall supporting state before the large-angle fixed-point takeoff of the present invention;

[0038] Fig.10 It is a side view of the overall supporting state of the present invention before taking off at a large angle;

[0039] Explanation of the reference numerals: 1. front wing; 2. rear wing; 3. connecting rod of front and rear wings; 4. aluminum alloy transverse folding part; 5. vertical tail; 6. elevator; 7. battery compartment; 8. load compartment; 9. battery; 10. solar panel; 11. inner ring propeller and motor; 12. outer ring propeller and motor; 13. connecting rod junction box; 14. vertical tail connector; 15. electronic speed governor; 16. airborne avionics equipment; 17. transverse connecting rod; 18. connector; 19. supporting carbon tube; 20. front upper support; 21. front middle three-way piece; 22. front lower support; 23. rear lower support; 24. vertical tail support. DETAILED DESCRIPTION

[0040] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, but should not be construed as limiting the present invention.

[0041] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0042] Based on the problems that the single-type propeller of the existing tail-seat configuration aircraft consumes a lot of energy and has low efficiency in the cruising stage, resulting in a short flight time; the existing plateau ecological monitoring solar-powered UAVs are large in size, need to be disassembled and assembled, have poor portability, and cannot meet the requirements of single-person use. The present invention provides a distributed power fixed-point take-off and landing portable solar-powered UAV, comprising a front wing and a rear wing arranged in a tandem wing form and a folding component connected therebetween, wherein the leading edges of the front wing and the rear wing are each provided with a plurality of rotors along the span direction, and the four rotors located in the middle of the front wing and the rear wing in the span direction are respectively located at the four vertices of a quadrilateral, forming a four-rotor power system of the UAV, and the remaining rotors form a fixed-wing power system of the UAV; the folding component connects the front wing and the rear wing into a tandem wing with a spatial height difference, and the front wing and the rear wing can be stacked by deformation.

[0043] Specifically, the spatial height difference between the front wing and the rear wing is 0.32 meters to 0.38 meters. The aspect ratio of the front wing is 3.9 to 4.2; the aspect ratio of the rear wing is 3.8 to 4.0.

[0044] Specifically, the front wing and the rear wing serve as the main lifting surfaces, and the upper surfaces thereof are evenly covered with solar panels. Four rotors are arranged along the span direction of the leading edges thereof, and the eight rotors are respectively located at the vertices of the inner and outer quadrilaterals. The four rotors located in the inner ring are symmetrically installed on the leading edges of the middle parts of the front and rear wings of the UAV along the middle symmetry plane of the UAV, so as to provide lift during the take-off and landing stages, and control the flight attitude of the UAV by means of power differential; the four rotors located in the outer ring are symmetrically installed on the leading edges of the wingtips of the front and rear wings of the UAV along the middle symmetry plane of the UAV, so as to provide thrust during the fixed-wing cruise stage, and resist wind by means of power differential during the take-off and landing stages.

[0045] Specifically, when the UAV is in a vertical landing state, the four rotors of the inner ring form a square in a top view, and the center of gravity of the UAV is located at the center of the square.

[0046] Specifically, vertical tail wings are respectively installed at both ends of the rear wing, and the two vertical tail wings are symmetrically distributed along the middle symmetry plane of the UAV; and elevator ailerons are symmetrically hinged at the trailing edges of both ends of the rear wing.

[0047] Specifically, the folding assembly includes two front and rear wing connecting rods symmetrically distributed on the middle symmetry plane of the drone, one end of the front and rear wing connecting rod is connected to the front wing, and the other end is connected to the rear wing. Two centrally symmetrically installed aluminum alloy transverse folding parts are arranged in the middle section, so that the two ends of the front and rear wing connecting rods can be folded in reverse. After folding, the front and rear wing connecting rods are in a Z shape.

[0048] Specifically, a transverse connecting rod is vertically installed between the two front and rear wing connecting rods, the center of gravity of the UAV is located in the middle of the transverse connecting rod, and a battery compartment is installed at the center thereof. A battery is installed in the battery compartment to provide energy for the flight of the UAV.

[0049] Specifically, the rotor includes a motor and a propeller installed at the output end thereof, and the rotation speed of the motor is controlled by an electronic speed regulator, thereby driving the propeller to rotate.

[0050] Specifically, the UAV also includes a navigation system, a flight control system, a measurement and control system, airborne cables and a payload compartment; the payload compartment is located in the middle of the leading edge of the front wing, and the navigation system, the flight control system, and the measurement and control system are installed therein, and the airborne cables are distributed inside the front and rear wings and on the surface of each connecting rod.

[0051] The above technical solution is further described below in conjunction with the accompanying drawings:

[0052] Reference Figure 1-Figure 4 As shown, this embodiment is a distributed power fixed-point take-off and landing portable solar-powered UAV, which includes three parts: an airframe structure, an energy power system, and an airborne avionics system.

[0053] The body structure includes: front wing 1, rear wing 2, front and rear wing connecting rod 3, aluminum alloy transverse folding part 4, vertical tail 5, elevator aileron 6, battery compartment 7, load compartment 8, connecting rod junction box 13, vertical tail connecting piece 14, transverse connecting rod 17 and connecting piece 18. The front wing 1 and rear wing 2 are the main lifting surfaces of the UAV, and the two form a tandem wing layout. Considering the portability requirements, they are designed as small aspect ratio straight wings. The wingspan of the front wing 1 is 1.2m and the chord length is 0.3m. The wingspan of the rear wing 2 is 1.2m and the chord length is 0.31m. The airfoil with high lift coefficient is selected to meet the needs of the cruise condition and increase the range and flight time of the UAV. The vertical tail 5 is installed at the end of the rear wing 2 as the vertical stabilizer of the UAV. The vertical tail 5 is connected to the rear wing 2 through the vertical tail connecting piece 14. The front wing 1 and the rear wing 2 are connected by the front and rear wing connecting rods 3. A connector 18 is installed at the intersection of the front and rear wing connecting rods 3 and the wing spar to realize multi-point connection between the front and rear wing connecting rods 3 and the wing, thereby improving the strength and rigidity of the structure. Two transverse connecting rods 17 are installed between the two front and rear wing connecting rods 3. The installation position is coordinated and determined according to the design center of gravity position of the entire drone. A battery compartment 7 is installed in the middle position of the transverse connecting rod 17 to place the battery 9 required by the drone. The transverse connecting rod 17 and the front and rear wing connecting rods 3 are fixedly connected through the connecting rod junction box 13, so that the connecting rod part forms an "H"-shaped layout, thereby improving the anti-torsion ability of the drone structure. A load compartment 8 is installed in the middle of the leading edge of the front wing 1 to place the airborne avionics equipment 16. An integrated design is adopted to combine the load compartment 8 with the structure of the front wing 1 to reduce the size of the drone and reduce the weight of the drone. The rudder surface of the drone of the present invention includes two elevons 6 symmetrically hinged to the outer position of the trailing edge of the rear wing 2, and the flight control of the drone is realized together with the power differential mode.

[0054] Reference Figure 5-Figure 8 As shown, four aluminum alloy transverse folding members 4 are symmetrically installed on the two front and rear wing connecting rods 3, and the two folding members near the front wing are installed opposite to the two folding members near the rear wing to achieve reverse folding. After the aluminum alloy transverse folding members 4 reach the folding limit point, the length and height of the drone are reduced, which reduces the size of the drone and improves the portability of the drone.

[0055] The energy power system includes: a battery 9, a solar panel 10, an inner ring propeller and a motor 11 (rotor), an outer ring propeller and a motor 12, and an electronic speed regulator 15. The battery 9 uses a high energy density lithium battery, which is installed in the battery compartment 7 to provide energy for the drone. The solar panel 10 uses a flexible thin-film solar cell with high photoelectric conversion efficiency, which is evenly laid on the upper surface of the front wing 1 and the rear wing 2 to provide energy for the flight of the drone and play the role of solar energy range extension. There are four inner ring propellers and motors 11, which are symmetrically installed on the middle leading edges of the front wing 1 and the rear wing 2 along the middle symmetry plane of the UAV. They are mainly used to provide lift during take-off and landing, and to control the flight attitude of the UAV by means of power differential. Therefore, the inner ring propeller adopts a large-size low-pitch propeller, and the inner ring motor adopts a low-kv value brushless DC motor that matches the inner ring propeller to drive the rotation of the propeller; the inner ring motor is installed on a motor base that is integrated with the wing structure. To meet the requirements of the quad-rotor mode, the installation position of the inner ring propeller and the motor 11 needs to make the inner ring propeller form a square in the top view in the vertical landing state, and the design center of gravity of the UAV needs to be in the middle of the square. There are four outer ring propellers and motors 12, which are symmetrically installed on the leading edges of the wingtips of the front wing 1 and the rear wing 2 along the middle symmetrical plane of the drone. They are mainly used to provide thrust during the fixed-wing cruise phase and resist wind through power differential during the take-off and landing phase. Therefore, the outer ring propeller adopts a large-pitch propeller with higher efficiency at a high forward ratio, and the outer ring motor adopts a low-kv value brushless DC motor that matches the outer ring propeller. Similarly, the outer ring motor is also installed on a motor seat that is integrated with the wing structure. The installation of the inner ring propeller and motor 11 and the outer ring propeller and motor 12 needs to consider their distance from the front and rear wing connecting rods 3 and the load compartment 8, and a certain safety distance needs to be left. The electronic speed regulator 15 is fixed to the bottom of the battery compartment 7 to control the speed of the motor.

[0056] The airborne avionics system includes airborne avionics equipment 16 and airborne cables (not shown). The airborne avionics equipment 16 is distributed and installed in the payload compartment 8, including a navigation system, a flight control system, and a measurement and control system. The airborne cables are distributed inside the front wing 1, the rear wing 2, and on the surface of the front and rear wing connecting rods 3 and the transverse connecting rods 17. Cable ties and tapes are used to fix the exposed parts of the airborne cables to the fuselage. It is necessary to reduce the number of airborne cables through reasonable arrangement, and select lighter airborne cables to reduce the total weight of the drone.

[0057] Reference Figure 9-10 As shown, the large-angle fixed-point take-off bracket for the UAV of this embodiment is used for overall support of the UAV before take-off, and includes two parts: a front tiltable support member and a rear fixed support member.

[0058] The front tiltable support member includes: a support carbon tube 19, a front upper support member 20, a front middle three-way member 21, and a front lower support member 22. There are three support carbon tubes 19, which connect the front upper support member 20, the front middle three-way member 21, and the front lower support member 22 as a whole. They are detachable, which reduces the consumables of the support members and increases the portability of the support members. The length of the support carbon tube 19 is determined according to the take-off angle of the drone. The upper part of the front upper support member 20 is an arc less than 180°, which is supported under the middle part of the front beam of the front wing 1, and the lower part is a sleeve, which is sleeved with the support carbon tube 19. The front upper support member 20 needs to be able to provide support for the drone before take-off, and to be detached from the drone in time after being disturbed by the drone's take-off. The front middle three-way member 21 is a sleeve assembly with a certain angle between each other, connecting the support carbon tubes 19 in three directions. The front lower support member 22 is two sleeve members with bases, which are respectively connected to the two oblique supporting carbon tubes 19. The base can increase the contact area between the front tiltable support member and the ground, and increase the stability of the support in the static state. However, the base cannot be too large. It is necessary to ensure that the front tiltable support member can tilt forward after being disturbed by the drone takeoff to avoid collision with other parts of the drone and ensure the stability of the drone takeoff.

[0059] The rear fixed support members include two groups of rear lower support members 23 and vertical tail support members 24, which are respectively placed at the lower part of the two vertical tails of the drone. A groove is provided on the upper part of the vertical tail support member 24 according to the shape of the vertical tail of the drone, which is used to place the vertical tail and limit the lateral displacement of the drone in the initial stage of take-off, maintain the predetermined take-off angle of the drone, and ensure take-off safety. The rear lower support member 23 provides support for the vertical tail support member 24 in three directions, and it is an integrated design with the vertical tail support member 24. The rear fixed support member is a non-dumpable form and is a fixed support.

[0060] Working status:

[0061] The flight process of the distributed power fixed-point take-off and landing portable solar drone of the present invention includes: a large-angle fixed-point take-off phase, a take-off transition phase, a fixed-wing cruise phase, a landing descent phase, a landing transition phase, and a fixed-point vertical landing phase. The following describes the specific working method by describing each flight phase of the drone of this embodiment:

[0062] During the large-angle fixed-point takeoff phase, the drone takes off from the ground at a large angle at the takeoff point. At the moment of takeoff, the throttle command is large enough so that the vertical component of the power can overcome gravity. The drone accelerates off the ground under the pull of the propeller, and the upper and lower wings are used to control the pitch, and the left and right wings are used to control the roll and yaw. After reaching a certain speed, the rudder effect of the elevon is sufficient to control the attitude of the drone, so the elevon begins to work, the elevon controls the pitch and roll, and the left and right side power differentials coordinate to eliminate sideslip.

[0063] After the UAV climbs to the specified height according to the given climbing trajectory, it enters the take-off transition phase. The UAV gradually lowers its head, reduces the pitch angle and increases the speed. During this period, the thrust distribution strategy is switched to distribute the desired thrust of the UAV to the outer ring propeller until the UAV reaches the cruising level flight speed and enters the fixed-wing cruise phase when the track angle is reduced to 0°.

[0064] During the fixed-wing cruise phase, the drone performs predetermined tasks such as ecological monitoring.

[0065] During the landing descent phase, the drone receives the landing command, determines the coordinates of the landing point through the recognition and positioning algorithm, and then adjusts the flight attitude to make the drone track the descent trajectory. The pitch and roll angles are controlled by the elevator ailerons, and the left and right side power differential coordination eliminates side slip.

[0066] During the landing transition phase, the drone quickly starts to pull up after descending to the specified height, and the pitch angle of the drone is increased by controlling the elevons and the front and rear propellers differentially. During this period, the thrust distribution strategy is switched to distribute the desired thrust of the drone to the inner ring propeller until the drone reaches a vertical state and the inner ring propeller thrust completely balances the gravity. During this period, the lateral disturbances to the drone are balanced by the elevons and the outer ring propellers. After reaching the vertical state, the drone switches to the quadcopter mode for landing.

[0067] During the fixed-point vertical landing phase, the drone lands vertically in a fixed-point manner in quadrotor mode. The inner ring propeller pull balances gravity, and the outer ring propeller pull generates the attitude control torque of the drone. The drone flies to the landing point along the landing trajectory. When the drone is 1 to 2 meters off the ground, the drone is controlled to lower its head and slowly lie on the ground to complete the fixed-point vertical landing goal.

[0068] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A distributed power fixed-point take-off and landing portable solar-powered drone, characterized by: The invention comprises a front wing and a rear wing arranged in a tandem wing form and a folding assembly connected therebetween. The leading edges of the front wing and the rear wing are both provided with a plurality of rotors along the span direction. The four rotors located in the middle of the front wing and the rear wing in the span direction are respectively located at the four vertices of a quadrilateral, forming a four-rotor power system of the UAV, and the remaining rotors form a fixed-wing power system of the UAV. The folding assembly connects the front wing and the rear wing into a tandem wing with a spatial height difference, and the front wing and the rear wing can be stacked by deformation.

2. According to claim 1, a distributed power fixed-point take-off and landing portable solar-powered UAV is characterized by: The spatial height difference between the front wing and the rear wing is 0.32 meters to 0.38 meters; the aspect ratio of the front wing is 3.9-4.2; and the aspect ratio of the rear wing is 3.8-4.

0.

3. According to claim 1, a distributed power fixed-point take-off and landing portable solar-powered UAV is characterized by: The front wing and the rear wing serve as the main lifting surfaces, and the upper surfaces thereof are evenly covered with solar panels. Four rotors are arranged on the leading edges thereof along the span direction, and the eight rotors are respectively located at the vertices of the inner and outer quadrilaterals. The four rotors located in the inner ring are symmetrically installed on the leading edges of the middle parts of the front and rear wings of the UAV along the middle symmetric plane of the UAV, so as to provide lift during the take-off and landing stages, and control the flight attitude of the UAV by means of power differential; the four rotors located in the outer ring are symmetrically installed on the leading edges of the wingtips of the front and rear wings of the UAV along the middle symmetric plane of the UAV, so as to provide thrust during the fixed-wing cruising stage, and resist wind by means of power differential during the take-off and landing stages.

4. According to claim 3, a distributed power fixed-point take-off and landing portable solar-powered UAV is characterized by: When the UAV is in a vertical landing state, the four rotors of the inner ring form a square in a top view, and the center of gravity of the UAV is located at the center of the square.

5. According to claim 1, a distributed power fixed-point take-off and landing portable solar-powered UAV is characterized by: The two end portions of the rear wing are respectively provided with vertical tail wings, and the two vertical tail wings are symmetrically distributed along the middle symmetry plane of the UAV; the trailing edges of the two ends of the rear wing are symmetrically hinged with elevator ailerons.

6. According to claim 1, a distributed power fixed-point take-off and landing portable solar-powered UAV is characterized by: The folding assembly includes two front and rear wing connecting rods symmetrically distributed on the middle symmetry plane of the drone, one end of the front and rear wing connecting rod is connected to the front wing, and the other end is connected to the rear wing. Two aluminum alloy transverse folding parts installed symmetrically in the middle section are arranged, so that the two ends of the front and rear wing connecting rods can be folded in reverse. After folding, the front and rear wing connecting rods are in a Z shape.

7. A distributed power fixed-point take-off and landing portable solar-powered UAV according to claim 6, characterized in that: A transverse connecting rod is vertically installed between the two front and rear wing connecting rods. The center of gravity of the UAV is located in the middle of the transverse connecting rod, and a battery compartment is installed at the center of the transverse connecting rod. A battery is installed in the battery compartment to provide energy for the flight of the UAV.

8. According to claim 1, a distributed power fixed-point take-off and landing portable solar-powered UAV is characterized by: The rotor includes a motor and a propeller installed at the output end thereof. The rotation speed of the motor is controlled by an electronic speed regulator, thereby driving the propeller to rotate.

9. According to claim 1, a distributed power fixed-point take-off and landing portable solar-powered UAV is characterized by: The UAV also includes a navigation system, a flight control system, a measurement and control system, airborne cables and a payload compartment; The load compartment is located in the middle of the leading edge of the front wing, and a navigation system, a flight control system, and a measurement and control system are installed therein. The onboard cables are distributed inside the front and rear wings and on the surfaces of each connecting rod.

10. A take-off support frame for a portable solar-powered UAV capable of taking off and landing at a distributed power point according to any one of claims 1 to 9, characterized in that: It includes a front tiltable support and a rear fixed support, which determine the take-off angle of the drone to be 45°; the tiltable support is used to support the front wing of the drone, and the tiltable support tilts forward at the moment of take-off; the rear fixed support is used to support the rear wing of the drone.

Images