Solar-powered unmanned aerial vehicle gliding test method and aerodynamic parameter back-calculation method

Abstract

The application provides a solar unmanned aerial vehicle gliding test method and a method for inversely calculating aerodynamic parameters. The method comprises the following steps: driving a propeller to drive a solar unmanned aerial vehicle to accelerate and run on a runway by using a motor at a preset rotating speed; when the solar unmanned aerial vehicle reaches a preset height, the rotating speed of the motor is reduced from the preset rotating speed to zero, and a theoretical sliding center line of the solar unmanned aerial vehicle is offset according to a preset lateral deviation; and the solar unmanned aerial vehicle is caused to land from the preset height until landing on the ground to test the lateral deviation landing performance of the solar unmanned aerial vehicle. The technical scheme of the application is used to solve the technical problem that it is difficult to verify the lateral deviation landing performance of the unmanned aerial vehicle in the prior art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar unmanned aerial vehicle, and particularly relates to a solar unmanned aerial vehicle sliding and gliding test method and a method for inversely calculating aerodynamic parameters. BACKGROUND

[0002] The unmanned aerial vehicle sliding test, also known as the unmanned aerial vehicle sliding and running test, is a large-scale ground test with high complexity, great technical difficulty and wide cooperation. The work correctness and coordination of each subsystem of the unmanned aerial vehicle and the ground equipment can be confirmed through the ground sliding and running test before the first flight, and the control performance of the unmanned aerial vehicle in the ground sliding and running is checked, so as to release the risk in advance. Compared with the conventional unmanned aerial vehicle, the solar unmanned aerial vehicle can autonomously obtain the energy required for maintaining flight from the outside during flight, and can theoretically realize "infinite endurance", so the application prospect is wide. In order to realize high-altitude long-endurance day and night flight, a low wing load, large wing span and large aspect ratio layout is usually adopted, and the take-off and landing speed and the flight speed are low, and the sliding and running distance is short, so the side landing performance and the aerodynamic performance need to be focused on. However, the current sliding and running test is a non-ground test, which cannot truly verify the side landing performance of the unmanned aerial vehicle, and the current aerodynamic performance verification method is usually through wind tunnel test and flight test, and the wind tunnel test still has a certain gap from the real flight condition, and the flight test has great risk. SUMMARY

[0003] In order to solve one of the problems in the prior art, the present application provides a solar unmanned aerial vehicle sliding and gliding test method and a method for inversely calculating aerodynamic parameters.

[0004] According to one aspect of the present application, a solar unmanned aerial vehicle sliding and gliding test method is provided, and the method comprises the following steps.

[0005] A motor is used to drive a propeller at a preset rotating speed to accelerate the sliding and running of the solar unmanned aerial vehicle on a runway.

[0006] When the solar unmanned aerial vehicle reaches a preset height, the rotating speed of the motor is reduced from the preset rotating speed to zero, and a theoretical sliding center line of the solar unmanned aerial vehicle is offset according to a preset lateral deviation.

[0007] The solar unmanned aerial vehicle is caused to land from the preset height until landing on the ground to test the side landing performance of the solar unmanned aerial vehicle.

[0008] Further, the method further comprises: collecting the air speed, the ground speed, the dynamic pressure and the propeller windmill resistance in real time during the process that the solar unmanned aerial vehicle lands from the preset height until landing on the ground.

[0009] Further, the method further comprises judging whether the solar unmanned aerial vehicle reaches a preset safety control condition during the accelerating sliding and running, if not, the accelerating sliding and running is continued until the preset height is reached, and if yes, the rotating speed of the motor is reduced from the preset rotating speed to zero.

[0010] Furthermore, the preset security control conditions are:

[0011] The indicated airspeed of the solar-powered UAV is greater than or equal to the rolling speed threshold; and / or

[0012] The distance between the solar-powered drone's position and the starting point is greater than or equal to the rolling distance threshold; and / or

[0013] The pitch angle of the solar-powered drone is less than the pitch angle threshold; and / or

[0014] The lateral deviation of the solar-powered drone exceeds the lateral deviation threshold; and / or

[0015] The heading angle deviation of the solar-powered UAV is greater than the heading angle deviation threshold.

[0016] According to another aspect of the present invention, a method for inverse calculation of aerodynamic parameters of a solar-powered UAV is provided, which inversely calculates the aerodynamic parameters of the solar-powered UAV based on the total mass and wing loading of the solar-powered UAV and the sky speed, ground speed, dynamic pressure, and propeller windmill resistance collected by the aforementioned gliding test method of the present invention.

[0017] Furthermore, the aerodynamic parameters include the lift coefficient and the drag coefficient. The aerodynamic parameters of the solar drone are calculated as follows:

[0018] Inversely calculate the lift coefficient based on dynamic pressure, wing loading, and sky speed;

[0019] The drag coefficient is calculated based on the dynamic pressure, wing loading, total aircraft mass, propeller windmill resistance, sky speed and ground speed.

[0020] Furthermore, inversely calculating the lift coefficient based on the dynamic pressure, the wing loading, and the sky speed includes: calculating an extreme value of the mean square error of the lift coefficient based on the dynamic pressure, the wing loading, and the sky speed, and using the lift coefficient corresponding to the extreme value of the mean square error of the lift coefficient as the inversely calculated lift coefficient.

[0021] Furthermore, inversely calculating the drag coefficient based on the dynamic pressure, wing loading, total aircraft mass, propeller windmill resistance, sky speed, and ground speed includes: calculating an extreme value of the mean square deviation of the drag coefficient based on the dynamic pressure, wing loading, total aircraft mass, propeller windmill resistance, sky speed, and ground speed, and using the drag coefficient corresponding to the extreme value of the mean square deviation of the drag coefficient as the inversely calculated drag coefficient.

[0022] Furthermore, the extreme value of the mean square error of the lift coefficient is calculated using the following formula:

[0023]

[0024] In the above formula, W y (C y ,v y0represents the mean square error of the lift coefficient, q represents the dynamic pressure at the time t, C y represents the lift coefficient, delta represents the wing load, g represents the gravity acceleration, t represents the collection time in the process of the solar unmanned aerial vehicle descending from the preset height until landing on the ground, v y0 represents the vertical initial speed, v y represents the horizontal speed at the time t.

[0025] Further, the extreme value of the mean square error of the drag coefficient is calculated by the following formula:

[0026]

[0027] In the above formula, W x (C x represents the mean square error of the drag coefficient, C x represents the drag coefficient at the time t, V c represents the indicated airspeed at the time t, f p represents the propeller windmill drag coefficient at the time t, is equal to the ratio of the propeller windmill drag to the total machine mass, is related to the indicated airspeed, and phi represents the flight path angle, v d represents the ground speed at the time t, and v0 represents the initial ground speed.

[0028] The technical scheme of the present application provides a solar unmanned aerial vehicle gliding test method and a method for calculating aerodynamic parameters in reverse, which uses an electric motor to drive a propeller to accelerate the solar unmanned aerial vehicle on a runway until it reaches a preset height, then reduces the motor speed to zero and performs an autonomous offset operation on the aircraft, so that the unmanned aerial vehicle lands from the preset height to the landing ground in a gliding and side offset state, thereby testing its side landing performance. The method can effectively verify the performance of the unmanned aerial vehicle in non-runway centerline side landing, improve the authenticity and coverage of ground tests, and indirectly improve the safety and reliability of the solar unmanned aerial vehicle. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings included to provide a further understanding of the embodiments of the present application, constitute a part of the specification and serve to explain the principles of the present application together with the text. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 shows a flowchart of a solar unmanned aerial vehicle gliding test method provided by a specific embodiment of the present application;

[0031] Figure 2A safety control flow diagram of a solar unmanned aerial vehicle glide test is shown according to a specific embodiment of the present application;

[0032] Figure 3 A safety control flow diagram of a solar unmanned aerial vehicle glide test is shown according to a specific embodiment of the present application;

[0033] Figure 4 A safety control flow diagram of a solar unmanned aerial vehicle glide test is shown according to a specific embodiment of the present application. DETAILED DESCRIPTION

[0034] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings of the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The description of the at least one example embodiment is actually only illustrative, but not intended to limit the present application and its application or use in any way. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0035] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the example embodiments according to the present application. As used herein, the singular form is intended to include the plural form, unless the context clearly indicates otherwise, and it should also be understood that when the terms "comprise" and / or "include" are used in the specification, there is a presence of the features, steps, operations, devices, components and / or combinations thereof.

[0036] Unless specifically stated otherwise, the relative arrangements of the components and steps, numerical expressions, and values shown in the embodiments are not meant to limit the scope of the present application. At the same time, it should be understood that the sizes of the various parts shown in the drawings are not drawn in proportion to the actual proportions. The techniques, methods and devices known to those skilled in the relevant art can not be discussed in detail, but should be considered as part of the authorized specification, if appropriate. In all examples shown and discussed herein, any specific value should be interpreted as merely exemplary, and not as a limitation. Therefore, other examples of the example embodiments can have different values. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further discussed in subsequent drawings.

[0037] As Figure 1As shown, the embodiment of the application provides a solar unmanned aerial vehicle gliding test method, which comprises the following steps:

[0038] S1, driving the propeller with a preset rotating speed to accelerate the solar unmanned aerial vehicle to slide on the runway;

[0039] S2, when the solar unmanned aerial vehicle reaches the preset height, the rotating speed of the motor is reduced to zero from the preset rotating speed, and the theoretical sliding center line of the solar unmanned aerial vehicle is offset according to the preset lateral deviation;

[0040] S3, making the solar unmanned aerial vehicle land from the preset height until landing to test the lateral landing performance of the solar unmanned aerial vehicle.

[0041] The specific value of the preset rotating speed is determined according to the configuration of the solar unmanned aerial vehicle. As an embodiment of the application, the solar unmanned aerial vehicle uses a double-GPS and double-redundant differential positioning system to provide high-precision position information including height, the landing gear layout uses a bicycle type landing gear, and the power device uses an electric motor + propeller. The specific value of the preset height is also determined according to the configuration of the solar unmanned aerial vehicle. For example, in the embodiment of the application, the preset height value is 1.5m.

[0042] With this configuration, a solar unmanned aerial vehicle gliding test method is provided, which uses an electric motor to drive the propeller to accelerate the solar unmanned aerial vehicle to slide on the runway until it reaches a preset height, and then reduces the rotating speed of the motor to zero and performs autonomous offset operation on the aircraft, so that the unmanned aerial vehicle lands from the preset height to landing with the superposition of gliding and lateral deviation, thereby testing its lateral landing performance. This method can effectively verify the performance of the unmanned aerial vehicle in the non-runway center line lateral landing, improve the authenticity and coverage of ground tests, and indirectly improve the safety and reliability of the solar unmanned aerial vehicle. Compared with the prior art, the technical solution of the application can solve the technical problem that the lateral landing performance of the unmanned aerial vehicle is difficult to verify in the prior art.

[0043] In order to ensure the safety of the solar unmanned aerial vehicle to be tested, the gliding test method further comprises judging whether the solar unmanned aerial vehicle reaches a preset safety control condition during the acceleration sliding process. If not, the acceleration sliding continues until the preset height is reached. If yes, the rotating speed of the motor is reduced to zero from the preset rotating speed. Here, reducing the rotating speed of the motor from the preset rotating speed to zero is an autonomous emergency handling process designed for the unmanned aerial vehicle reaching the preset safety control condition.

[0044] Specifically, in the embodiment of the application, the preset safety control condition is:

[0045] 1) the indicated airspeed of the solar unmanned aerial vehicle is greater than or equal to the sliding speed threshold; and / or

[0046] 2) the distance between the position of the solar-powered unmanned aerial vehicle and the starting point is greater than or equal to the sliding distance threshold value; and / or

[0047] 3) the pitch angle of the solar-powered unmanned aerial vehicle is less than the pitch angle threshold value; and / or

[0048] 4) the lateral deviation of the solar-powered unmanned aerial vehicle is greater than the lateral deviation threshold value; and / or

[0049] 5) the heading angle deviation of the solar-powered unmanned aerial vehicle is greater than the heading angle deviation threshold value.

[0050] Before the sliding test is performed, the solar-powered unmanned aerial vehicle performs static verification of the safety control measures based on the real state, specifically, the speed threshold value, the sliding distance threshold value, the pitch angle threshold value, the lateral deviation threshold value, and the heading angle deviation threshold value are bound to the solar-powered unmanned aerial vehicle, and the position, the heading deviation, and the like are simulated by using a differential reference station (dual-redundant differential positioning system) bias, a dual-GPS azimuth bias, and the like, so as to verify the effectiveness of the autonomous emergency processing flow of the unmanned aerial vehicle under the fault condition. In addition, the preset height can also be bound to the solar-powered unmanned aerial vehicle, and the solar-powered unmanned aerial vehicle is verified whether it can execute the set flow when the simulated height reaches the preset height in the process of performing the static verification of the foregoing safety control measures, so as to improve the safety of the test.

[0051] In order to more clearly understand the sliding test method provided by the present application, the foregoing processes will be described in detail below in combination with the embodiments of Figure 2 , Figure 3 and Figure 4 . It can be known by those skilled in the art that the examples are only for the purpose of more clearly understanding the sliding test method provided by the present application, and do not limit the technology thereof in any way.

[0052] As shown in Figure 2 and Figure 3 , first, the static verification method of the safety control measures described above is performed, and after the verification is correct, the ground station opens the energy storage battery on the unmanned aerial vehicle to supply power, the energy storage battery independently supplies power to the on-board equipment to make the unmanned aerial vehicle power on, and the unmanned aerial vehicle powers on to interact with the ground station to autonomously complete the processes of on-board equipment self-checking, parameter binding, inertial navigation conversion, parameter binding, and pre-takeoff state judgment. After judging that the pre-takeoff state is normal, the on-board equipment autonomously judges the lateral deviation of the actual position of the unmanned aerial vehicle and the center line of the runway, and the heading angle deviation of the heading of the unmanned aerial vehicle and the direction of the runway, and the unmanned aerial vehicle has takeoff conditions after meeting the requirements. Then, the ground starts the enable switch, sends the motor speed control instruction through the wireless link to start the motor, and the on-board equipment autonomously judges whether the starting of the motor is normal through the speed control instruction and the feedback speed.

[0053] After the motor starts normally, the solar cell output is turned on, the solar cell supplies power to the aircraft, and a "take-off" command is sent to the drone. After receiving the "take-off" command, the aircraft controls the motor controller to drive the motor and propeller windmill according to the bound motor speed (the preset motor speed) to generate pulling force, thereby driving the drone to accelerate and run. First, the aileron differential is used to complete the wing level control. The drone changes from three-wheel (main wheel, tail wheel, and one side of the wing auxiliary wheel are grounded) taxiing to wing level state (main wheel and tail wheel are grounded) taxiing, and then the elevator is used to complete the pitch control. The drone changes from two-wheel taxiing to single-wheel taxiing (only the main wheel is grounded).

[0054] During the acceleration and rolling process, the radio altimeter (dual GPS) and dual redundant differential positioning system are used to measure the height of the UAV from the ground at all times. Figure 4 As shown, when the aircraft continuously determines that one or more of the two sensors of the altimeter and the differential system have a ground clearance height greater than or equal to the preset height, the following processes are automatically executed in sequence: ① The aircraft autonomously sends a 0 speed command to the power unit. After receiving the command, the power unit gradually reduces the speed to 0 according to the motor speed gradient limit; ② The aircraft autonomously performs the offset operation, and according to the size and direction of the preset lateral deviation, the theoretical runway centerline of the UAV is offset to the left or right. The deviation DY between the actual position of the UAV and the theoretical runway centerline after the offset is DY pr +DY0, where DY pr = represents the preset lateral deviation, with left deviation being positive and right deviation being negative. DY0 represents the deviation between the actual position of the drone and the theoretical runway centerline before the deviation was set. ③ The drone corrects its deviation mid-air along the deflected runway centerline, while simultaneously decelerating due to aerodynamic drag and propeller windmill resistance, reducing aerodynamic lift. Of course, if the drone meets safety control conditions during the test, then proceed to steps ① and / or ③.

[0055] As aerodynamic lift decreases, the drone lands with a sideways deviation under the action of gravity, realistically simulating a single-wheel landing situation where the drone's actual position is not on the runway center during takeoff and landing. Subsequent observation and related tests confirm the normal operation of the landing gear and airframe structure to evaluate the sideways landing performance. After landing, the drone further decelerates due to ground friction resistance. The drone gradually transitions from single-wheel taxiing on the main wheels to taxiing on both the main wheels and tail wheels, and uses the tail wheel and rudder to coordinate and correct the deviation. After the drone's speed drops to a predetermined value, the MPPT controller output is automatically shut down, thereby disconnecting the solar cell power supply output. The onboard control surfaces return to zero, and the onboard power is shut down on the ground, concluding the drift test.

[0056] Moreover, in the embodiment of the present application, the method further comprises: collecting the air speed, the ground speed, the dynamic pressure and the propeller windmill resistance of the solar-powered unmanned aerial vehicle during the process from the preset height falling to landing on the ground in real time. In this way, the aerodynamic parameters of the solar-powered unmanned aerial vehicle can be further inversely calculated according to the data.

[0057] Based on the above embodiment, according to another aspect of the present application, there is provided an aerodynamic parameter inverse calculation method of a solar-powered unmanned aerial vehicle, which inversely calculates the aerodynamic parameters of the solar-powered unmanned aerial vehicle according to the total machine mass, the wing load and the air speed, the ground speed, the dynamic pressure and the propeller windmill resistance collected by the aforementioned gliding test method.

[0058] Among them, the aerodynamic parameters include the lift coefficient and the drag coefficient, and the inverse calculation of the aerodynamic parameters of the solar-powered unmanned aerial vehicle includes:

[0059] The lift coefficient is inversely calculated according to the dynamic pressure, the wing load and the air speed;

[0060] The drag coefficient is inversely calculated according to the dynamic pressure, the wing load, the total machine mass, the propeller windmill resistance, the air speed and the ground speed.

[0061] Further, as a specific embodiment of the present application, the inverse calculation of the lift coefficient according to the dynamic pressure, the wing load and the air speed includes: calculating the extreme value of the mean square deviation of the lift coefficient according to the dynamic pressure, the wing load and the air speed, and taking the lift coefficient corresponding to the extreme value of the mean square deviation of the lift coefficient as the inversely calculated lift coefficient; and the inverse calculation of the drag coefficient according to the dynamic pressure, the wing load, the total machine mass, the propeller windmill resistance, the air speed and the ground speed includes: calculating the extreme value of the mean square deviation of the drag coefficient according to the dynamic pressure, the wing load, the total machine mass, the propeller windmill resistance, the air speed and the ground speed, and taking the drag coefficient corresponding to the extreme value of the mean square deviation of the drag coefficient as the inversely calculated drag coefficient.

[0062] In the embodiment of the present application, the extreme value of the mean square deviation of the lift coefficient is calculated by the following formula:

[0063]

[0064] In the above formula, W y (C y ,v y0 represents the mean square deviation of the lift coefficient, q represents the dynamic pressure at time t, C y represents the lift coefficient, δ represents the wing load, g represents the gravitational acceleration, t represents the collection time during the process from the preset height falling to landing on the ground of the solar-powered unmanned aerial vehicle, v y0 represents the vertical initial speed, v y represents the air speed at time t, and in this embodiment, the extreme value refers to the minimum value. When the minimum value of the mean square deviation of the lift coefficient is calculated, the vertical initial speed, i.e., the inversely calculated vertical initial speed, can also be obtained.

[0065] Further, in the embodiment of the present application, the propeller windmill resistance factor after the motor + propeller power device is stopped is considered, that is, the extreme value of the mean square deviation of the resistance coefficient is calculated through the following formula:

[0066]

[0067] In the above formula, W x (C x , v0) represents the mean square deviation of the resistance coefficient, C x represents the resistance coefficient, V c represents the indicated airspeed at t, f p represents the propeller windmill resistance coefficient at t, which is equal to the ratio of the propeller windmill resistance to the total machine mass, is related to the indicated airspeed, and represents the flight path angle, v d represents the ground speed at t, and v0 represents the initial ground speed. In this embodiment, the extreme value refers to the minimum value. When the minimum value of the mean square deviation of the resistance coefficient is calculated, the initial ground speed can also be obtained, that is, the initial ground speed is inversely calculated.

[0068] Further, the theoretical lift coefficient and the theoretical resistance coefficient of the unmanned aerial vehicle can be calculated by using the pitch angle, rudder angle and other telemetry data in the gliding test, and interpolating the theoretical aerodynamic data. The actual lift coefficient and the actual resistance coefficient obtained by the gliding test are compared with the theoretical lift coefficient and the theoretical resistance coefficient, so that the aerodynamic characteristic deviation of the unmanned aerial vehicle can be inversely calculated relatively accurately, which serves as the basis for aerodynamic data correction, and improves the accuracy of the aerodynamic data of the solar unmanned aerial vehicle. Through the gliding test, the aerodynamic characteristics of the unmanned aerial vehicle in the near-ground section can be verified in all states, and the problem that the aerodynamic characteristics of the solar unmanned aerial vehicle are difficult to inversely calculate before the first flight is solved.

[0069] In summary, the present application provides a solar unmanned aerial vehicle gliding test method and aerodynamic parameter inverse calculation method. The method uses an electric motor to drive a propeller to accelerate the solar unmanned aerial vehicle on a runway until it reaches a predetermined height, and then reduces the motor speed to zero and performs an on-board self-bias operation, so that the unmanned aerial vehicle lands from the predetermined height to the landing ground in a gliding and side-bias superposition state, thereby testing its side-bias landing performance. The method can effectively verify the performance of the unmanned aerial vehicle in the non-runway centerline side-bias landing, improve the authenticity and coverage of the ground test, and indirectly improve the safety and reliability of the solar unmanned aerial vehicle. Compared with the prior art, the technical scheme of the present application can solve the technical problem that the side-bias landing performance of the unmanned aerial vehicle is difficult to verify in the prior art.

[0070] For purposes of the description hereinafter, the terms "upper", "lower", "right", "left", "rear", "front", "vertical" and "horizontal" as can be perceived herein relative to the accompanying drawings refer to the orientation of the components being described. However, it is to be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device described herein relative to the other device or structure is inverted, then a spatially relative term such as "above" can be interpreted as meaning "below" or "below" can be interpreted as meaning "above". The device can also be oriented in other ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. The devices can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0071] In addition, it should be pointed out that the use of the terms "first", "second" and the like in connection with various elements is merely intended for identification, and does not constitute a special meaning, and therefore cannot be interpreted as a limitation on the scope of protection of the present application.

[0072] The preferred embodiments of the present application are described above in detail. The present application, however, is not limited to the above embodiments, but can be variously modified and changed by those skilled in the art without departing from the scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of the present application.

Claims

1. A solar-powered UAV gliding test method, characterized in that: The method comprises: The electric motor drives the propeller at a preset speed to drive the solar-powered drone to accelerate and glide on the runway; When the solar-powered drone reaches a preset height, the speed of the motor is reduced from the preset speed to zero and the theoretical gliding centerline of the solar-powered drone is offset according to a preset lateral deviation; The solar-powered UAV is made to descend from the preset height until it touches the ground to test the sideways landing performance of the solar-powered UAV.

2. The method according to claim 1, characterized in that The method further includes: collecting in real time the sky speed, ground speed, dynamic pressure, and propeller windmill resistance of the solar-powered UAV during the process of landing from the preset height to the ground.

3. The method according to claim 2, characterized in that The method further includes determining whether the solar-powered UAV reaches a preset safety control condition during the acceleration and taxiing process; if not, continuing the acceleration and taxiing until the preset height is reached; and if so, reducing the speed of the motor from the preset speed to zero.

4. The method according to claim 3, characterized in that The preset security control conditions are: The indicated airspeed of the solar-powered UAV is greater than or equal to the rolling speed threshold; and / or The distance between the solar-powered drone's position and the starting point is greater than or equal to the rolling distance threshold; and / or The pitch angle of the solar-powered drone is less than the pitch angle threshold; and / or The lateral deviation of the solar-powered drone exceeds the lateral deviation threshold; and / or The heading angle deviation of the solar-powered UAV is greater than the heading angle deviation threshold.

5. A method for back-calculating aerodynamic parameters of a solar-powered UAV, characterized in that: The aerodynamic parameters of the solar-powered UAV are calculated based on the total mass and wing loading of the solar-powered UAV and the sky speed, ground speed, dynamic pressure and propeller windmill resistance collected by the gliding test method according to any one of claims 2 to 4.

6. The method according to claim 5, characterized in that The aerodynamic parameters include lift coefficient and drag coefficient. The aerodynamic parameters of the solar drone are calculated by reverse calculation: inversely calculating the lift coefficient based on the dynamic pressure, the wing loading, and the sky speed; The drag coefficient is inversely calculated based on the dynamic pressure, the wing loading, the total aircraft mass, the propeller windmill resistance, the sky speed, and the ground speed.

7. The method according to claim 6, characterized in that Inversely calculating the lift coefficient based on the dynamic pressure, the wing load, and the sky speed includes: calculating an extreme value of a mean square error of the lift coefficient based on the dynamic pressure, the wing load, and the sky speed, and using the lift coefficient corresponding to the extreme value of the mean square error of the lift coefficient as the inversely calculated lift coefficient.

8. The method according to claim 7, characterized in that Reverse calculating the drag coefficient based on the dynamic pressure, the wing loading, the total aircraft mass, the propeller windmill resistance, the sky speed, and the ground speed includes: calculating an extreme value of the mean square deviation of the drag coefficient based on the dynamic pressure, the wing loading, the total aircraft mass, the propeller windmill resistance, the sky speed, and the ground speed, and using the drag coefficient corresponding to the extreme value of the mean square deviation of the drag coefficient as the reversely calculated drag coefficient.

9. The method according to claim 8, characterized in that The extreme value of the mean square error of the lift coefficient is calculated using the following formula: In the above formula, W y (C y ,v y0 ) represents the mean square error of lift coefficient, q represents the dynamic pressure at time t, C y represents the lift coefficient, δ represents the wing load, g represents the acceleration of gravity, t represents the acquisition time during the process of the solar-powered UAV descending from the preset height to landing, v y0 Indicates the vertical initial velocity, v y represents the speed at time t.

10. The method according to claim 9, characterized in that The extreme value of the mean square deviation of the drag coefficient is calculated using the following formula: In the above formula, W x (C x ,v0) represents the mean square error of the drag coefficient, C x Represents the resistance coefficient, V c represents the indicated airspeed at time t, f p The propeller windmill drag coefficient at time t is equal to the ratio of the propeller windmill drag to the total mass of the aircraft and is related to the indicated airspeed. φ represents the track inclination angle. v d represents the ground speed at time t, and v0 represents the initial ground speed.

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