A test device and test method for longitudinal aerodynamic characteristics of fixed-wing UAV at high angle of attack

Abstract

A fixed-wing UAV high-angle-of-attack longitudinal aerodynamic characteristics test device and test method relate to the technical field of aircraft aerodynamic characteristics testing, and mainly include: wind tunnel simulation equipment, UAV load and motion simulation equipment, sensors arranged on the UAV or a model, and a data acquisition system, etc., for simulating the longitudinal motion state and posture of the UAV in various aerodynamic environments; the device is used to conduct experiments to obtain the nonlinear longitudinal aerodynamic characteristics of the UAV under various angles of attack, obtain a phase diagram reflecting the relationship between the system state attack angle and pitch angular velocity change, and determine the balance point under normal working conditions and extreme working conditions, so as to provide a basis for the flight control of the UAV under extreme working conditions with a high angle of attack.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft aerodynamic characteristics testing, and in particular to a fixed-wing unmanned aerial vehicle high-attack-angle longitudinal aerodynamic characteristics testing device and a testing method. Background Art

[0002] The UAV high angle of attack longitudinal aerodynamic characteristics test is an experiment to study the flight characteristics of the UAV at a large angle of attack. During the flight, the UAV may face external interference factors such as strong winds and airflows, which may cause changes in flight parameters and thus affect the flight performance and stability of the UAV.

[0003] At high angles of attack, the lift of the aircraft will tend to decrease, and during the process of descending, the aircraft will stall. When the lift and power are insufficient, the aircraft will become unstable and fall faster. Therefore, the current flight control algorithm of fixed-wing UAVs will try to keep the angle of attack within a small range. However, in some working conditions (such as rapid landing in a specified section), fixed-wing UAVs need to decelerate quickly to stop, but the aerodynamic drag coefficient of the UAV is small within the small angle of attack range, and it cannot provide sufficient braking force to achieve rapid braking.

[0004] Therefore, when designing and developing UAVs, understanding the aerodynamic characteristics of UAVs at high angles of attack is crucial to improving the flight performance and stability of UAVs. By conducting experimental research on the longitudinal aerodynamic characteristics of UAVs at different angles of attack, the aerodynamic performance of UAVs such as lift, drag, and pitch moment under different flight conditions can be obtained, providing an important reference for designing flight control systems and improving flight attitude stability.

[0005] In current UAV design and development, the longitudinal aerodynamic characteristics at high angles of attack are generally studied through numerical calculation and simulation analysis methods, and there is still a lack of experimental research on the aerodynamic characteristics of UAVs at high angles of attack. Summary of the invention

[0006] The present invention provides a fixed-wing UAV large angle of attack longitudinal aerodynamic characteristics test device and test method, the fixed-wing UAV longitudinal aerodynamic characteristics are measured experimentally, the nonlinear longitudinal aerodynamic characteristics of the UAV under large angle of attack are obtained according to the obtained data, and the steady-state equilibrium solution of the angle of attack and the pitch angular velocity in the phase plane constituted by the angle of attack and the pitch angular velocity state of the UAV and the unstable equilibrium solution under the large angle of attack extreme working condition are further found, so as to provide a basis for improving the stability of the control of the UAV under extreme working conditions.

[0007] The test device provided by the present disclosure is used to simulate the high-angle-of-attack flight state of a fixed-wing UAV and measure the longitudinal aerodynamic characteristics of the UAV at a high angle of attack, and mainly includes:

[0008] Wind tunnel simulation equipment, drone carrying and motion simulation equipment, sensors arranged on drones or models, and data acquisition systems, including:

[0009] Wind tunnel simulation equipment, used to simulate the wind field and aerodynamic environment of a UAV flying at a high angle of attack;

[0010] UAV load-bearing and motion simulation equipment is used to fix the load of the UAV to be tested and complete its longitudinal movement and attitude adjustment, including the adjustment of different angles of attack and maintaining different angular velocities to move back and forth, so as to simulate the flight state of the UAV at various pitch angular velocities and angles of attack;

[0011] The wind tunnel simulation equipment is set on both sides of the drone carrying and motion simulation equipment, with the air outlet facing the drone activity area;

[0012] Sensors placed on the drone or model are used to measure the aerodynamic parameters of the drone when flying at a high angle of attack;

[0013] The data acquisition system is used to collect data obtained by sensors in real time.

[0014] Furthermore, the UAV carrying and motion simulation equipment includes:

[0015] The bottom bearing device is fixed on the wind tunnel test bench;

[0016] Two longitudinal support rods are perpendicular to the bottom load-bearing plane and upward, and the plane formed by the two longitudinal support rods faces the wind tunnel outlet;

[0017] A transverse connecting rod is provided between the two longitudinal supporting rods, the middle part of the transverse connecting rod is disconnected and connected to the UAV support and pitch angle adjustment device, and motors are provided at both ends of the transverse connecting rod; driven by the motor, the UAV support and pitch angle adjustment device can rotate with the transverse connecting rod as the rotation axis;

[0018] At the same time, a support rod perpendicular to the transverse connecting rod is provided in the UAV support and pitch angle adjustment device, which is used to support and fix the UAV or its scaled model along the main axis of the UAV body, so that when the UAV support and pitch angle adjustment device rotates with the transverse connecting rod as the rotation axis, the UAV can perform longitudinal movement in a plane perpendicular to the plane where the two longitudinal support rods are located.

[0019] Furthermore, the sensor comprises:

[0020] The balance installed inside the drone body is used to monitor the force and torque information of the drone in three directions during the experiment;

[0021] The angle of attack sensor is used to measure the change of the angle of attack of the transmission UAV during the experiment in real time.

[0022] The method for testing the longitudinal aerodynamic characteristics of a fixed-wing UAV at a high angle of attack based on the above device mainly includes the following steps:

[0023] S1, assembly and debugging of UAV longitudinal aerodynamic characteristics test equipment;

[0024] S2, conduct steady-state longitudinal mechanical property test experiments on the UAV, including: adjusting the test device to produce different pitch angular velocities, respectively matching different wind speeds and different elevator deflections to conduct experiments, and collecting aerodynamic lift, drag and drag moment data at a specified angle of attack through the test bench in real time, where the wind tunnel wind speed is regarded as the flight speed of the UAV in the airspace;

[0025] S3, according to the experimental data, is fitted and Relative to the variables , , The functional relationship of In body coordinate system The aerodynamic force in the axial direction, The body coordinate system is Aerodynamic torque of the shaft, For around The pitch angular velocity of the axis, is the angle of attack, For elevator deflection;

[0026] S4, using the functional relationship obtained in step S3, fix the elevator deflection , respectively, from the system states under multiple different random initial conditions - Start by calculating , The value of the next moment is obtained, and the system state is reflected under the rudder deviation condition. - The phase diagram of the change relationship is shown, and the equilibrium points under normal working conditions and extreme working conditions are determined, that is, point;

[0027] S5, analyzes the changing trend of the system near the equilibrium point and provides a basis for the control of the UAV under extreme working conditions.

[0028] Furthermore, in step S2:

[0029] The different pitch angular speeds include: one or more of 10° / s, 15° / s, 20° / s, 25° / s, 30° / s, 35° / s, 40° / s, 45° / s, and 50° / s;

[0030] The different wind speeds include: one or more of 0 m / s, 5 m / s, 10 m / s, 15 m / s, and 20 m / s;

[0031] The different elevator deflections include: one or more of 0°, 5°, 10°, 15°, 20°, and 25°;

[0032] The specified angle of attack includes one or more of 0°, 3°, 6°, 9°, 12°, 15°, 18°, 21°, 24°, 27°, and 30°.

[0033] Furthermore, in step S3, and Relative to the variables , , The functional relationship is:

[0034]

[0035]

[0036] in: is the air density, V is the speed of the drone relative to the air, represents the total surface area of ​​the aircraft wing, is the average aerodynamic chord of the aircraft;

[0037] , For wingspan, is the reference flight speed;

[0038] , , , , , is the aerodynamic drag coefficient Calculate the required correlation coefficient, , , , is the aerodynamic lift coefficient Calculate the required correlation coefficient, , , , is the aerodynamic pitch moment coefficient Calculate the required correlation coefficients;

[0039] The aerodynamic coefficients are obtained by fitting the aerodynamic data obtained from the wind tunnel test.

[0040] Furthermore, the method for drawing the phase diagram in step S4 specifically includes:

[0041] Fixed elevator deflection , from the system state under a random initial condition - To begin, use the dynamics formula for angle of attack and pitch rate:

[0042]

[0043]

[0044] calculate , The value of , get the change trend of the next moment, and then draw the continuously changing system state - The curve of

[0045] In the formula, is the body coordinate system The speed of the direction, is the pitch angle, , Determined during the test, In the body coordinate system The moment of inertia of the axis is measured experimentally after the UAV is assembled;

[0046] The phase diagram is formed by drawing the change curves under multiple different initial states.

[0047] Furthermore, the method further comprises the following steps:

[0048] Using the functional relationship obtained in step S3, by fixing the elevator deflection, the system balance equation is directly solved:

[0049]

[0050]

[0051] The equilibrium solutions under different rudder deflection conditions are obtained to provide a reference for determining the equilibrium point in step S4.

[0052] Compared with the prior art, the beneficial effects of the present invention are: (1) it can realistically simulate the flight state of the UAV at various pitch angular velocities and angles of attack, and obtain a large amount of relevant test data of the pitch angular velocities and angles of attack; (2) the steady-state equilibrium solution at a large angle of attack is obtained by experimental methods; (3) it can solve the mechanism problem that at a large angle of attack, the strong adverse pressure gradient causes a large flow separation, and under the coupling effect of separation and turbulence, the separated vortex structure at the trailing edge of the airfoil is continuously enhanced and the stall phenomenon occurs, and find out the unstable equilibrium solution of the system at a large angle of attack, and provide a control reference for the study of the control capability of the UAV under the extreme working condition of large angle of attack. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] The above and other objects, features and advantages of the present disclosure will become more apparent through a more detailed description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present disclosure.

[0054] Figure 1 It is a schematic diagram of the overall structure of an exemplary embodiment of a UAV aerodynamic characteristics test device according to the present disclosure;

[0055] In the figure, 1-carrying device, 2-connecting frame, 3-lateral connecting rod, 4-pitch angle adjustment motor, 5-pitch angle adjustment device, 6-drone, 7-connecting rod, 8-fixing mechanism;

[0056] Figure 2 Schematic diagram of data processing during the experiment. DETAILED DESCRIPTION

[0057] The preferred embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the preferred embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present disclosure more thorough and complete, and to fully convey the scope of the present disclosure to those skilled in the art.

[0058] The present invention provides a large angle of attack longitudinal aerodynamic characteristics test device for fixed-wing UAV, which is used to measure the relationship between angle of attack and pitch angular velocity. The experimental system is mainly used to obtain the dynamic characteristics of the UAV under a wide range of angle of attack changes.

[0059] According to an exemplary embodiment of the test device disclosed in the present invention, the overall structure is shown in FIG. Figure 1 As shown, it mainly includes:

[0060] (1) A carrying device 1, used to carry the test UAV and fixed on the wind tunnel test bench as a bottom support;

[0061] (2) a supporting device, used to fix the pre-test UAV on the carrying device, and the supporting device is used to adjust the posture of the pre-test UAV and realize the control of the pitch angular velocity of the UAV;

[0062] In this embodiment, the supporting device specifically includes: a connecting frame 2 vertically upward with the carrying device 1, a transverse connecting rod 3 provided between the longitudinal supporting rods of the connecting frame, a pitch angle adjusting device 5 for adjusting the pitch angle of the drone (the pitch angle adjusting device 5 is connected to the motor 4 through the transverse connecting rod 3), a connecting rod 7 supporting the drone, and a fixing mechanism 8 connecting and fixing the connecting rod 7 to the pitch angle adjusting device 5;

[0063] (3) Motor 4, which accurately adjusts the pitch angle of the aircraft and can control the drone to move continuously at a fixed angular velocity;

[0064] (4) A data acquisition device for acquiring the pitch angular velocity of the pre-test UAV and the lift and drag of the test UAV.

[0065] (5) A balance, placed inside the drone, for testing the six forces of the pre-test drone, such as lift and drag, wherein the bottom end of the balance is fixedly arranged on the top of the balance mounting platform, and the top end of the balance is fixed to the pre-test drone.

[0066] As a preference, the bearing device and the supporting device are assembled using 40 profiles;

[0067] In order to reduce the impact of the device itself on the airflow during the experiment, the diameter of the device should not be smaller than the diameter of the wind tunnel.

[0068] In an exemplary embodiment, the process of conducting a high-angle-of-attack longitudinal aerodynamic characteristic test of a UAV using the above-mentioned device is as follows:

[0069] 1. Test equipment assembly

[0070] (1) Fix the load-bearing device on the wind tunnel test bench.

[0071] (2) The connecting frame is assembled and installed on the supporting device.

[0072] (3) Install the motor and transverse connecting rod on the stand.

[0073] (4) Install the pitch angle adjustment device and connect it to the motor through a transverse connecting rod.

[0074] The device is tested to ensure that it can complete various working conditions during the experiment, including the adjustment of different angles of attack and the maintenance of back-and-forth motion at different angular velocities.

[0075] (5) Install a balance inside the drone to monitor the force and torque on the drone in three directions during the experiment. Install an angle of attack sensor to measure and transmit the change of the angle of attack of the drone in real time during the experiment. Install a data acquisition device.

[0076] (6) Fix the wiring harness of the data acquisition device to the machine body or the test stand to avoid affecting the data collection and transmission during the experiment.

[0077] (7) Fix the drone with the balance on the connecting rod so that it can be easily fixed to the pitch angle adjustment device.

[0078] (8) Fix the drone using a fixing mechanism.

[0079] 2. Preliminary experiment

[0080] First, conduct experiments at smaller yaw, roll, and pitch angles with different wind speeds to ensure that the device and the drone can generate and transmit data normally during the experiment.

[0081] 3. The adjustment device generates different pitch angular velocities (10° / s, 15° / s, 20° / s, 25° / s, 30° / s, 35° / s, 40° / s, 45° / s, 50° / s) and is matched with different wind speeds (0m / s, 5m / s, 10m / s, 15m / s, 20m / s) and different elevator deflections (0°, 5°, 10°, 15°, 20°, 25°) to conduct experiments and collect aerodynamic lift, drag and drag moment data at the specified attack angle (0°, 3°, 6°, 9°, 12°, 15°, 18°, 21°, 24°, 27°, 30°) through the test bench in real time. Since the aircraft is stationary, the wind tunnel wind speed can be regarded as the flight speed of the drone in the airspace. This step is a steady-state longitudinal mechanical property test experiment of the drone.

[0082] 4. Analyze and process the collected angle information, force and torque information to obtain aerodynamic data at different attack angles, wind speeds and pitch angle velocities, and summarize the initial phase diagram, as shown in the attached figure. Figure 2 The balance point curve shown is used to find the balance point under different angles of attack and pitch angular velocities. According to the changes in the balance point, it lays the foundation for the derivation of control theory of the UAV under extreme working conditions.

[0083] The specific process is described as follows:

[0084] (1) The expression of aerodynamic coefficient in the aerodynamic model is as follows:

[0085] (1.1)

[0086] (1.2)

[0087] (1.3)

[0088] in, , , , , , is the aerodynamic drag coefficient Calculate the required correlation coefficient, , , , is the aerodynamic lift coefficient Calculate the required correlation coefficient, , , , is the aerodynamic pitch moment coefficient Calculate the required correlation coefficients, obtained by fitting the wind tunnel test data;

[0089] for , For wingspan, is the reference flight speed.

[0090] Through coordinate transformation, the lift coefficient and drag coefficient Converted into aerodynamic force in body coordinate system Axis and Axis force coefficient , :

[0091] (1.4)

[0092] (1.5)

[0093] Multiplying this coefficient by the aircraft and flow field related parameters, we can get the aerodynamic force in the body coordinate system. Axis force and the rotation in the body coordinate system Aerodynamic torque of the shaft :

[0094] (1.6)

[0095] (1.7)

[0096] in is the dynamic pressure in the flow field, represents the total surface area of ​​the aircraft wing, is the average aerodynamic chord of the aircraft. Substituting formulas 1.1, 1.2, 1.3, and 1.5 into formulas 1.6 and 1.7, we can see that in the body coordinate system Aerodynamic force in the axial direction and the rotation in the body coordinate system Aerodynamic torque of the shaft It's around Pitch angular velocity of the axis , Angle of attack 、Pitch rudder Function:

[0097] (1.8)

[0098] (1.9)

[0099] The aerodynamic data obtained from the experiment can be used to fit the aerodynamic coefficients in equations 1.8 and 1.9 to obtain the aerodynamic characteristics.

[0100] (2) This experimental system is mainly aimed at studying the dynamic characteristics under a wide range of angles of attack, mainly involving longitudinal motion and force, and the state variables involved are in the body coordinate system. Speed ​​of direction , Speed ​​of direction , Speed , around Pitch angular velocity of the axis The longitudinal motion equations consist of two translational equations and one rotational equation:

[0101] (1.10)

[0102] (1.11)

[0103] (1.12)

[0104] in, Indicates the body coordinate system Axis force, Indicates the body coordinate system Axis force, The torque generated by the engine thrust in the body coordinate system Axis component, , , In the body coordinate system , , The moment of inertia of the shaft, Represents the rotation in the body coordinate system The aerodynamic torque of the axis. , To solve:

[0105] (1.13)

[0106] (1.14)

[0107] in, The engine thrust in the body coordinate system is The force on the shaft, , The aerodynamic force is expressed in the body coordinate system Axis and The force of the axis. is the roll angle, is the pitch angle.

[0108] Angle of attack It's speed and body The angle between the axes, and the angle of attack can be solved by the vertical and longitudinal velocities:

[0109] (1.15)

[0110] The angle of attack is used to reflect the aircraft state under extreme conditions. and At the same time, under the test conditions, considering that there is no thrust and the corresponding torque, and at the rolling angular velocity and yaw rate is 0, Speed ​​of direction is 0, the roll angle The longitudinal dynamics model is simplified to obtain the dynamics formulas for the angle of attack and pitch angular velocity:

[0111] (1.16)

[0112] (1.17)

[0113] According to the longitudinal dynamic model, by fixing the elevator deflection ,exist Draw a series of different initial states in the plane and The initial system state change line is drawn into a phase diagram, and the stability of each equilibrium point is observed and analyzed in the phase diagram.

[0114] The method of drawing the phase diagram is as follows:

[0115] The system state from multiple random states under different initial conditions - First, use (1.16) and (1.17) to calculate , The value of , get the change trend of the next moment, and then draw the continuously changing system state - The curve is composed of multiple changing curves under different states, that is, the phase diagram is drawn.

[0116] in, , It can be determined during the test process that , The calculation is performed using equations 1.8 and 1.9, where the aerodynamic coefficients are obtained by fitting the test data.

[0117] Determination of the balance point:

[0118] For a nonlinear system , where x is the state variable and u is the input variable. Let the state and input is the equilibrium solution of the system, that is, the equilibrium point of the system appears in the state and the corresponding input At this point, all the state derivatives of the system are 0, that is,

[0119] (1.18)

[0120] So it should be The system reaches equilibrium.

[0121] Figure 2 In the obtained phase diagram, each solid line represents a state trajectory that changes from a certain initial state. The arrow indicates the direction of movement of the system state. The system will tend to develop towards a stable state, which is the direction pointed by the arrow. The normal operating equilibrium point and the large angle of attack limit operating equilibrium point in the figure are represented by asterisks and crosses, respectively.

[0122] Normal working condition balance point, when the system state is around this point, the system state will tend to approach this point, at this time the system state is in the stable zone. When the system is at this stable balance point, the entire system enters a stable balance.

[0123] In addition, the two extreme operating equilibrium points are unstable equilibrium points. When the system state is around this point, it tends to move away from this point. On one side of this point, the state value of the system will diverge, while on the other side it will move toward the stable equilibrium point and tend to be stable. This is the critical stable state of the system.

[0124] By analyzing the phase diagram equilibrium solution, the stable state of the equilibrium solution with different rudder deflections is obtained. By learning and analyzing the unstable equilibrium solution, the control system is used to approach the unstable equilibrium solution under extreme working conditions, thereby realizing the control of the UAV under extreme working conditions and completing more extreme work tasks.

[0125] (3) You can also fix the elevator , use numerical methods to solve the equilibrium point and provide a reference for determining the equilibrium point in the phase diagram.

[0126] Depend on The following equation can be obtained:

[0127] (1.19)

[0128] (1.20)

[0129] From formulas (1.8) and (1.9), it can be inferred that in the body coordinate system of this equation group Aerodynamic force in the axial direction and the rotation in the body coordinate system Aerodynamic torque of the shaft yes , , The function of yes The function of and yes , , Function, let and The solution of equations 1.19 and 1.20 can be obtained by fitting through wind tunnel tests. and about , , The values ​​of each linear coefficient in the function.

[0130] Set the pitch angular velocity , Angle of attack , elevator deflection In order to make the solution of this system of equations valid, there are only three unknown quantities when solving the system of equations composed of 1.19 and 1.20: the pitch angular velocity , Angle of attack , elevator deflection However, there are only two equations in this system, and obviously, in order to solve this system, one of the three unknowns must be restricted. Therefore, we can specify , to solve the equations in and .

[0131] In this system of equations, except and Other unknown quantities Control adjustment is a known quantity, in the body coordinate system Speed ​​of direction Since the wind speed under the test conditions is regarded as the speed direction, the x-direction component of the wind speed in the body coordinate system is , pitch angle Under the experimental constraints, there is no roll angle and yaw angle between the earth coordinate system and the body coordinate system. The angle between the earth coordinate system and the body coordinate system is the pitch angle, that is, when the fuselage is horizontal, it is 0°, and the pitch deflection angle is the pitch angle. , we can solve equations 1.19 and 1.20 to obtain equilibrium solutions for different rudder deflections.

[0132] The above technical scheme is only an exemplary embodiment of the present invention. For those skilled in the art, it is easy to make various types of improvements or modifications based on the application methods and principles disclosed in the present invention, and it is not limited to the method described in the above specific embodiment of the present invention. Therefore, the method described above is only preferred and does not have a restrictive meaning.

Claims

1. A method for testing the longitudinal aerodynamic characteristics of a fixed-wing UAV at a high angle of attack based on a UAV longitudinal aerodynamic characteristics test device, the device comprising: Wind tunnel simulation equipment, drone carrying and motion simulation equipment, sensors arranged on drones or models, and data acquisition systems, including: Wind tunnel simulation equipment, used to simulate the wind field and aerodynamic environment of UAVs flying at high angles of attack; UAV load-bearing and motion simulation equipment is used to fix the load of the UAV to be tested and complete its longitudinal movement and attitude adjustment, including the adjustment of different angles of attack and maintaining different angular velocities to move back and forth, so as to simulate the flight state of the UAV at various pitch angular velocities and angles of attack; The wind tunnel simulation equipment is set on both sides of the drone carrying and motion simulation equipment, with the air outlet facing the drone activity area; Sensors placed on the drone or model are used to measure the aerodynamic parameters of the drone when flying at a high angle of attack; Data acquisition system, used to collect data obtained by sensors in real time; The method comprises the following steps: S1, assembly and debugging of UAV longitudinal aerodynamic characteristics test equipment; S2, conduct steady-state longitudinal mechanical property test experiments on the UAV, including: adjusting the test device to produce different pitch angular velocities, respectively matching different wind speeds and different elevator deflections to conduct experiments, and collecting aerodynamic lift, drag and drag moment data at a specified angle of attack through the test bench in real time, where the wind tunnel wind speed is regarded as the flight speed of the UAV in the airspace; S3, according to the experimental data, is fitted and Relative to the variables , , The functional relationship of In body coordinate system The aerodynamic force in the axial direction, The body coordinate system is Aerodynamic torque of the shaft, For around The pitch angular velocity of the axis, is the angle of attack, For elevator deflection; S4, using the functional relationship obtained in step S3, fix the elevator deflection , respectively, from the system states under multiple different random initial conditions - Start by calculating , The value of the next moment is obtained, and the system state is reflected under the rudder deviation condition. - The phase diagram of the change relationship is shown, and the equilibrium points under normal working conditions and extreme working conditions are determined, that is, point; S5, analyzes the changing trend of the system near the equilibrium point to provide a basis for the control of the UAV under extreme working conditions; In the step S3, and Relative to the variables , , The functional relationship is: in: is the air density, V is the speed of the drone relative to the air, represents the total surface area of ​​the aircraft wing, is the average aerodynamic chord of the aircraft; , For wingspan, is the reference flight speed; , , , , , is the aerodynamic drag coefficient Calculate the required correlation coefficient, , , , is the aerodynamic lift coefficient Calculate the required correlation coefficient, , , , is the aerodynamic pitch moment coefficient Calculate the required correlation coefficients; The aerodynamic coefficients are obtained by fitting the aerodynamic data obtained from the wind tunnel test.

2. The method according to claim 1, characterized in that In step S2: The different pitch angular speeds include: one or more of 10° / s, 15° / s, 20° / s, 25° / s, 30° / s, 35° / s, 40° / s, 45° / s, and 50° / s; The different wind speeds include: one or more of 0 m / s, 5 m / s, 10 m / s, 15 m / s, and 20 m / s; The different elevator deflections include: one or more of 0°, 5°, 10°, 15°, 20°, and 25°; The specified angle of attack includes one or more of 0°, 3°, 6°, 9°, 12°, 15°, 18°, 21°, 24°, 27°, and 30°.

3. The method according to claim 1 or 2, characterized in that: The method for drawing the phase diagram in step S4 specifically includes: Fixed elevator deflection , from the system state under a random initial condition - To begin, use the dynamics formula for angle of attack and pitch rate: calculate , The value of , get the change trend of the next moment, and then draw the continuously changing system state - The curve of In the formula, is the body coordinate system The speed of the direction, is the pitch angle, , Determined during the test, In the body coordinate system The moment of inertia of the axis is measured experimentally after the UAV is assembled; The phase diagram is formed by drawing the change curves under multiple different initial states.

4. The method according to claim 1, characterized in that: The following steps are also included: Using the functional relationship obtained in step S3, by fixing the elevator deflection, the system balance equation is directly solved: The equilibrium solutions under different rudder deflection conditions are obtained to provide a reference for determining the equilibrium point in step S4.

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