A method for coordinated turning control of unmanned aerial vehicle flight lateral and longitudinal coupling

Abstract

The application discloses a kind of unmanned plane flight horizontal coupling's coordination turning control method, comprising: real-time acquisition flight state parameter, flight state parameter at least includes roll angle, sideslip angle, pitch angle and flight speed;The real-time sideslip angle collected with target sideslip angle is yaw trim, and the yaw trim control amount is obtained;According to yaw trim control amount adjustment flight sideslip tendency;Set the trigger condition of pull level mode, when triggering the pull level mode, according to flight speed, current roll angle and lift parameter, real-time planning roll transition trajectory, and the target convergence rate of roll angle and the allowable lateral deviation threshold value are calculated, so that roll angle converges;Wherein, target convergence rate is with the fastest convergence to the roll angle corresponding to lift safety threshold as convergence target, and the allowable lateral deviation threshold value is with guaranteeing longitudinal pull level stable threshold value as constraint boundary.The application solves the problem that unmanned plane pull level turning horizontal coupling control is insufficient, lift recovery and trajectory accuracy conflict is prominent.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) flight control technology, specifically to a coordinated turning control method for UAV flight with lateral and longitudinal coupling. Background Technology

[0002] Dive-type drones require steep dives to operate, with high speeds and large pitch angles. A relatively large roll angle during a high-speed dive can reduce vertical lift, potentially leading to insufficient lift and accidents during the subsequent pull-up. Furthermore, uncoordinated aileron and rudder control can cause sideslip spikes, increasing drag and hindering pull-up capability.

[0003] During a turn, a strong aerodynamic coupling exists between the lateral and longitudinal motions of a drone. When making a coordinated turn, the roll moment generated by the aileron deflection, while changing the heading, can easily increase the sideslip angle, causing asymmetry in lift on both sides of the wing and resulting in overall lift loss. Especially during low-altitude leveling landings or emergency leveling maneuvers, the drone must quickly recover and maintain sufficient lift to prevent stalling, eliminate sideslip as soon as possible, converge the roll angle to a safe range, and simultaneously control the lateral trajectory deviation within acceptable limits.

[0004] Currently, conventional flight control methods often decouple and independently design the longitudinal and lateral channels, failing to adequately consider the longitudinal-lateral coupling effect. During leveling maneuvers, such methods struggle to balance rapid lift recovery, sideslip suppression, and lateral trajectory accuracy. Excessive sideslip can lead to insufficient lift, or overly easing lateral deviations to prioritize lift recovery can result in uncontrolled trajectory and serious safety hazards. Furthermore, existing coordinated turn control systems lack consideration for control surface physical constraints and multi-target collaborative optimization, making it impossible to achieve optimal longitudinal-lateral coordination under complex conditions.

[0005] For example, in the prior art, Chinese invention patent CN103587681A discloses a control method for hypersonic vehicles that suppresses the influence of constant deviation in sideslip angle signals. This method achieves control by feeding back the roll angle integral to the rudder and ailerons, but it does not consider the lateral-longitudinal coupling effect and cannot achieve lateral-longitudinal coordination. Therefore, if the UAV moves relative to the target during its dive, it needs to adjust its flight direction in real time to continuously track the target. In this scenario, the core technical challenge is: how to achieve rapid convergence of the roll angle while ensuring that the lateral trajectory is within an acceptable range, and at the same time suppress the sideslip peak to provide sufficient lift for the longitudinal leveling maneuver and ensure the feasibility of the leveling mission; in addition, it is also necessary to solve the problem of real-time coordination and allocation between the ailerons and the rudder to avoid exacerbating flight risks due to control surface conflicts. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and solve the problems of insufficient lateral and longitudinal coupling control and prominent contradiction between lift recovery and trajectory accuracy when UAVs are turning horizontally, so as to provide a coordinated turning control method for UAVs with lateral and longitudinal coupling.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A coordinated turning control method for UAV flight with lateral and longitudinal coupling includes:

[0009] Real-time acquisition of flight status parameters, including at least roll angle, sideslip angle, pitch angle, and flight speed;

[0010] The collected real-time sideslip angle is compared with the target sideslip angle to perform yaw trim, resulting in yaw trim control values; the flight sideslip trend is then adjusted based on these yaw trim control values.

[0011] The flattening mode trigger condition is set. When the flight status parameters trigger the preset flattening mode, the roll transition trajectory is planned in real time based on the flight speed, current roll angle and lift parameters, and the target convergence rate and allowable lateral deviation threshold of the roll angle are calculated to make the roll angle converge. The target convergence rate is the roll angle that converges to the lift safety threshold as the convergence target, and the allowable lateral deviation threshold is the threshold that ensures longitudinal flattening stability as the constraint boundary.

[0012] Preferably, the method for obtaining the yaw trim control value includes:

[0013] Set the sideslip angle safety threshold Calculate the real-time sideslip angle and the target sideslip angle. The deviation from the target sideslip angle is used to obtain the sideslip angle deviation. ;

[0014] when At that time, the MPC controller is activated. The MPC controller performs rolling optimization based on the current flight state parameters and constraints, and outputs the optimal trim control surface increment. This value is then added to the previous trim value to obtain the yaw trim control quantity. until .

[0015] Preferably, the flattening mode triggering condition is as follows:

[0016] Preset flattening mode trigger threshold: height threshold Pitch angle threshold When the drone simultaneously meets and At that time, the flattening mode is triggered.

[0017] Preferably, the method for real-time planning of the rolling transition trajectory includes:

[0018] When the flight status parameters trigger the preset leveling mode and the current roll angle exceeds the roll angle safety threshold, the following steps are executed: Calculate the target convergence rate based on the current roll angle and flight speed; use a polynomial trajectory planning algorithm to generate a roll transition trajectory based on the current roll angle, target roll angle, and target convergence rate; constrain the convergence trajectory according to the set allowable lateral deviation and deviation change rate thresholds; and use PID control to output roll transition trajectory control commands until the preset mode switching conditions are met, switching to attitude stability maintenance mode.

[0019] Preferably, the expression for the target convergence rate is:

[0020] ;

[0021] in, For the target convergence rate, , These are matching coefficients used to ensure that the convergence speed is coordinated with the flight status; V is the current roll angle; V is the flight speed;

[0022] The expression for the roll transition trajectory is:

[0023] ;

[0024] The following boundary conditions must be met:

[0025] ;

[0026] Where t is time, The initial roll angle, For the target roll angle, The current roll angular velocity, and Based on the collected data, T represents the convergence time. for The derivative at time 0, for The derivative at time T;

[0027] The expression for the convergence time T is:

[0028] .

[0029] Preferably, the method for constraining the convergence trajectory based on a set allowable lateral deviation and a deviation change rate threshold specifically includes:

[0030] Set allowable lateral deviation for:

[0031] ;

[0032] in, The length of the drone fuselage. The deviation matching coefficient;

[0033] Set the threshold for the rate of change of deviation The allowable lateral deviation and the deviation change rate threshold are used as constraints for the MPC controller to constrain the convergence trajectory in real time, thereby limiting abrupt changes in the lateral trajectory.

[0034] Preferably, in the leveling mode, the method further includes controlling the aileron deflection and rudder deflection, wherein the control method for the aileron deflection and rudder deflection is as follows:

[0035] Based on the pre-constructed lateral and longitudinal coupled UAV dynamics prediction model, the collected current flight state parameters are used as the initial state of the prediction model to perform rolling pre-simulation of the UAV's sideslip angle dynamic response and lateral and longitudinal coupled motion trend within a preset prediction time domain, and output the prediction sequence of the sideslip angle changing with time and the prediction sequence of the lateral and longitudinal coupled motion state within a preset time period in the future.

[0036] The prediction model uses the roll angle, sideslip angle, flight speed and pitch angle of the UAV as state variables, and aileron deflection and rudder deflection as control variables.

[0037] With the combined optimization objectives of maximizing vertical lift recovery speed and minimizing sideslip peak, a constrained optimization equation for the control surface variables is established. The objective function of the constrained optimization equation includes a vertical lift recovery speed term and a sideslip peak term, and the vertical lift recovery speed term and the sideslip peak term are adjusted by weighting coefficients.

[0038] Combining the physical amplitude limit constraint of the control surface and the rate constraint of the actuator, the optimal aileron deflection and the optimal rudder deflection for each control cycle in the prediction time domain are solved within the feasible domain of the constraint optimization equation.

[0039] Based on the optimal aileron deflection and optimal rudder deflection obtained from the solution, control commands are output according to the control allocation ratio of the current control cycle.

[0040] Preferably, the parameters of the dynamic response trend of the sideslip angle include the sideslip suppression effect. ;

[0041] The parameters of the lateral and longitudinal coupling motion trend include the vertical lift recovery speed. and lateral trajectory deviation ;

[0042] The control surface quantity The constrained optimization equation is:

[0043] ;

[0044] in, The vertical lift recovery velocity is the derivative of lift with respect to time. for The weights; This refers to the sideslip suppression effect, i.e., the absolute value of the sideslip angle; For the sideslip peak term, The weights of the sideslip peak term, This is due to lateral trajectory deviation. To and Relevant weights; To allow the maximum sideslip angle, To allow for lateral deviation;

[0045] The feasible region of the constrained optimization equation is:

[0046] ;

[0047] ;

[0048] ;

[0049] in, For aileron deflection, To allow for the minimum deflection angle of the ailerons, To allow for the maximum deflection angle of the ailerons, For rudder deflection, To allow for the minimum rudder deflection angle, To allow for the maximum rudder deflection angle, To allow for the maximum deflection rate of the aileron, Maximum permissible rudder deflection rate This is the current sideslip angle;

[0050] The optimal aileron deflection and optimal rudder deflection for each control cycle in the prediction time domain are solved using a sequential quadratic programming algorithm.

[0051] Preferably, in the flattening mode, the control of lateral trajectory error adopts an error relaxation and recovery mechanism, the specific method of which is as follows:

[0052] Set a standard threshold for the lateral trajectory error when the flattening mode is not triggered. :

[0053] ;

[0054] Where L is the fuselage length;

[0055] Set the relaxation threshold for the lateral trajectory error when the flattening mode is triggered. :

[0056] ;

[0057] in, To allow for lateral deviation;

[0058] When the lateral error meets the error recovery trigger condition and the duration reaches a set time threshold, the error recovery mechanism is triggered; the error recovery mechanism is specifically as follows:

[0059] The threshold for lateral trajectory error is gradually reduced using an exponential decay method until it reaches the conventional threshold for lateral trajectory error. The expression for the exponential decay method is:

[0060] ;

[0061] in, The attenuation coefficient is... This is the threshold for lateral trajectory error.

[0062] Preferably, the error recovery triggering condition is:

[0063] ;

[0064] in, This is the current roll angle; The roll angle safety threshold, For vertical lift recovery velocity, To flatten the minimum lift increase rate required, the calibration is based on the aircraft model;

[0065] In the error recovery mechanism, if the following conditions are met: If the trajectory recovery is not immediately paused, the threshold for lateral trajectory error will be adjusted to the relaxation threshold.

[0066] This invention actively eliminates steady-state sideslip through yaw trim. In leveling mode, it dynamically plans the roll convergence trajectory based on lift safety requirements and uses allowable lateral deviation as a constraint to ensure the lift recovery speed required for longitudinal leveling while avoiding excessive lateral trajectory deviation. Furthermore, through a lateral-longitudinal coupled predictive optimization model, it comprehensively coordinates multiple objectives such as lift recovery, sideslip suppression, and lateral deviation, achieving optimal turning control under complex conditions. The error relaxation mechanism, under the premise of ensuring safety, defines a tolerable lateral trajectory adjustment range and trajectory recovery time, temporarily relaxing the lateral trajectory error to prioritize rapid roll angle convergence, creating safe conditions for longitudinal leveling. Once the roll angle stabilizes within a safe range and the longitudinal lift meets the leveling requirements, the lateral error index returns to the normal control standard, ensuring target tracking accuracy. This invention significantly improves the safety and control quality of low-altitude leveling turns for UAVs. Attached Figure Description

[0067] The present invention will now be described in further detail with reference to the accompanying drawings:

[0068] Figure 1 This is a method block diagram of the present invention;

[0069] Figure 2 This is a schematic diagram of the rolling transition trajectory of the present invention. Detailed Implementation

[0070] like Figure 1 As shown, the present invention provides a coordinated turning control method for lateral and longitudinal coupling of UAV flight, which includes the following steps.

[0071] First, flight status parameters are acquired in real time. These parameters include at least roll angle φ, sideslip angle β, pitch angle θ, and flight speed V; auxiliary information such as altitude H, vertical velocity, and angular rate can also be acquired. The target sideslip angle is typically set to 0 to achieve coordinated turns without sideslip.

[0072] The collected real-time sideslip angle is compared with the target sideslip angle to perform yaw trim, resulting in yaw trim control values. The flight sideslip trend is then adjusted based on these yaw trim control values. Specifically:

[0073] Set the sideslip angle safety threshold (For example =1°) and the target sideslip angle (taken as 0), calculate the real-time sideslip angle. The deviation from the target sideslip angle is used to obtain the sideslip angle deviation. .when At this time, the MPC controller is activated. The MPC controller embeds a sideslip angle dynamics prediction model with the rudder as the primary actuator. Using the current flight state as initial conditions, it performs a rolling optimization solution within the prediction time domain, outputting the optimal trim control surface increment. And the optimal trim control surface increment will be applied. The current yaw trim control value is obtained by summing the values ​​from the previous trim point. The rudder is then activated to eliminate sideslip. This process continues until... Maintain the current balance to keep the drone essentially in a no-sideslip state.

[0074] Set the flattening mode trigger condition to determine whether to trigger the flattening mode. Preset flattening mode trigger threshold: height threshold. Pitch angle threshold When the drone simultaneously meets and When the drone is in the leveling phase, the leveling mode is triggered.

[0075] Next, roll transition trajectory planning and control are performed in the leveling mode. When the flight status parameters trigger the preset leveling mode, the absolute value of the current roll angle is checked. Does it exceed the roll angle safety threshold? If the roll angle is within the safe range, the current attitude can be maintained or fine-tuned. If it is exceeded, a roll transition trajectory must be planned immediately to bring the roll angle to the roll angle corresponding to the lift safety threshold as quickly as possible. In this embodiment, a roll transition trajectory is planned in real time based on the flight speed, current roll angle, and lift parameters, and the target convergence rate and allowable lateral deviation threshold of the roll angle are calculated to ensure roll angle convergence. The target convergence rate is the fastest convergence to the roll angle corresponding to the lift safety threshold, and the allowable lateral deviation threshold is the constraint boundary to ensure longitudinal flattening stability. The roll angle corresponding to the lift safety threshold is the target roll angle. , usually take At this point, the wings are horizontal, and the lift is at its maximum and symmetrical.

[0076] The planning steps for the roll transition trajectory are as follows:

[0077] The target convergence rate is calculated based on the current roll angle and flight speed. The expression for the target convergence rate is:

[0078] ;

[0079] in, For the target convergence rate, , The matching coefficients are set according to the aircraft type to ensure that the convergence speed is coordinated with the flight status, so that the convergence speed increases with the roll angle deviation and the flight speed, and avoids aggressive control surface actions.

[0080] Calculate convergence time .

[0081] Determine the boundary conditions for the transition trajectory: initial roll angle (Current roll angle), Target roll angle Initial roll velocity (Obtained by sensors) Target roll angular velocity .

[0082] The roll transition trajectory is generated by an adaptive trajectory generator. Specifically, the adaptive trajectory generator uses a cubic polynomial trajectory planning algorithm to generate the roll transition trajectory based on the current roll angle, the target roll angle, and the target convergence rate. The polynomial coefficients a0 to a3 are solved using the above boundary conditions to obtain the desired roll angle time history.

[0083] That is, the expression for the roll transition trajectory is:

[0084] ;

[0085] The following boundary conditions must be met:

[0086] ;

[0087] Where t is time, The initial roll angle, For the target roll angle, The current roll angular velocity, and Based on the data collected, T represents the convergence time. In this embodiment, T is set to 0.5s. for The derivative at time 0, for The derivative at time T.

[0088] like Figure 2 As shown, =10°, , , .

[0089] Lateral constraints are generated based on the trajectory. Thresholds are set for allowed lateral deviation and the rate of change of deviation to constrain the convergent trajectory. Specifically:

[0090] Set allowable lateral deviation for:

[0091] ;

[0092] in, The length of the drone fuselage. This is the deviation matching coefficient.

[0093] Set the threshold for the rate of change of deviation The allowable lateral deviation and the deviation change rate threshold are used as constraints for the MPC controller to constrain the convergence trajectory in real time, thereby limiting abrupt changes in the lateral trajectory and ensuring that the lateral position deviation and its change rate caused by sideslip and roll coupling are limited to a safe range during the convergence roll angle process.

[0094] A PID controller is used to generate As a command, it outputs aileron deflection control values ​​to drive the UAV to execute a transition trajectory. It also monitors the roll angle in real time. and roll angular velocity Until the preset mode switching conditions are met ( ), switch to attitude stabilization maintenance mode.

[0095] In this embodiment, ignoring dimensions, the adjustment range of the PID controller's gain parameter is as follows:

[0096] ;

[0097] Among them, K p K is the proportional gain value. i K is the integral gain value. d This is the differential gain value. The control command is updated once per control cycle to ensure that the roll angle converges smoothly along the planned trajectory.

[0098] In the leveling mode, control of aileron and rudder deflection is also included. This control method operates in parallel or in fusion with the aforementioned control, further coordinating the aileron and rudder in leveling mode to achieve multi-objective optimization. Specifically, a lateral-longitudinal coupled UAV dynamics prediction model is constructed, using the UAV's roll angle, sideslip angle, flight speed, and pitch angle as state variables, and aileron and rudder deflection as control variables. In each control cycle, the current flight state is used as the initial state, and a rolling pre-simulation of the UAV's sideslip angle dynamic response and lateral-longitudinal coupled motion trend is performed within a preset prediction time domain. The predicted sequence of sideslip angle changes over time within a preset future time period and the predicted sequence of lateral-longitudinal coupled motion states are output.

[0099] With the combined optimization objectives of maximizing vertical lift recovery speed and minimizing sideslip peak, a constrained optimization equation for the control surface variables is established. The objective function of the constrained optimization equation includes a vertical lift recovery speed term and a sideslip peak term, and the vertical lift recovery speed term and the sideslip peak term are weighted and adjusted by weighting coefficients.

[0100] In this embodiment, the parameters of the dynamic response trend of the sideslip angle include the sideslip suppression effect. The parameters of the lateral and longitudinal coupling motion trend include the vertical lift recovery velocity. and lateral trajectory deviation .

[0101] rudder control quantity The constrained optimization equation is:

[0102] ;

[0103] in, The vertical lift recovery velocity is the derivative of lift with respect to time. for The weights; This refers to the sideslip suppression effect, i.e., the absolute value of the sideslip angle; For the sideslip peak term, The weights of the sideslip peak term, This is due to lateral trajectory deviation. To and Relevant weights; To allow the maximum sideslip angle, To allow for lateral deviation.

[0104] The feasible region of the constrained optimization equation is:

[0105] ;

[0106] ;

[0107] ;

[0108] in, For aileron deflection, To allow for the minimum deflection angle of the ailerons, To allow for the maximum deflection angle of the ailerons, For rudder deflection, To allow for the minimum rudder deflection angle, To allow for the maximum rudder deflection angle, To allow for the maximum deflection rate of the aileron, Maximum permissible rudder deflection rate This is the current sideslip angle.

[0109] Combining the physical amplitude limit constraint of the control surface and the speed constraint of the actuator, a sequential quadratic programming algorithm is used within the feasible region of the constraint optimization equation to solve for the optimal aileron deflection and the optimal rudder deflection for each control cycle in the prediction time domain.

[0110] Based on the optimal aileron deflection and optimal rudder deflection obtained from the solution, control commands are output according to the control allocation ratio of the current control cycle.

[0111] In the flattening mode, the control of lateral trajectory error adopts an error relaxation and recovery mechanism, the specific method of which is as follows:

[0112] Set a standard threshold for the lateral trajectory error when the flattening mode is not triggered. :

[0113] ;

[0114] Where L is the fuselage length.

[0115] Set the relaxation threshold for the lateral trajectory error when the flattening mode is triggered. :

[0116] ;

[0117] in, To allow for lateral deviation.

[0118] After the flattening mode is triggered, a relaxed threshold is initially used to obtain a larger lateral tolerance, prioritizing lift recovery. Simultaneously, lateral error is continuously monitored. When the lateral error meets the error recovery trigger condition and the duration reaches a set time threshold, the error recovery mechanism is triggered.

[0119] The error recovery trigger condition is:

[0120] ;

[0121] in, This is the current roll angle; The roll angle safety threshold, For vertical lift recovery velocity, The minimum lift increase rate required to level out is determined based on the aircraft model.

[0122] The error recovery mechanism is as follows:

[0123] The threshold for lateral trajectory error is gradually reduced using an exponential decay method until it reaches the conventional threshold for lateral trajectory error. The expression for the exponential decay method is:

[0124] ;

[0125] in, The attenuation coefficient is... This is the threshold for lateral trajectory error.

[0126] During the error recovery mechanism, if the following conditions are met: If the condition indicates that sideslip or attitude has worsened again, trajectory recovery is immediately paused, and the lateral trajectory error threshold is adjusted to the relaxation threshold. Attenuation resumes once the conditions are met again. This effectively balances trajectory accuracy and leveling safety.

[0127] Through the synergy of the above steps, the method of the present invention enables the UAV to recover symmetrical lift at the fastest speed during a turn, limit the sideslip angle to a safe range, and ensure that the lateral trajectory deviation is controllable, thereby significantly reducing the risk of stall and loss of control.

[0128] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A coordinated turning control method for lateral and longitudinal coupling in UAV flight, characterized in that, include: Real-time acquisition of flight status parameters, including at least roll angle, sideslip angle, pitch angle, and flight speed; The collected real-time sideslip angle is compared with the target sideslip angle to perform yaw trim, resulting in yaw trim control values; the flight sideslip trend is then adjusted based on these yaw trim control values. The flattening mode trigger condition is set. When the flight status parameters trigger the preset flattening mode, the roll transition trajectory is planned in real time based on the flight speed, current roll angle and lift parameters, and the target convergence rate and allowable lateral deviation threshold of the roll angle are calculated to make the roll angle converge. The target convergence rate is the roll angle that converges to the lift safety threshold as the convergence target, and the allowable lateral deviation threshold is the threshold that ensures longitudinal flattening stability as the constraint boundary.

2. The method according to claim 1, characterized in that: The method for obtaining the yaw trim control value includes: Set the sideslip angle safety threshold Calculate the real-time sideslip angle and the target sideslip angle. The deviation from the target sideslip angle is used to obtain the sideslip angle deviation. ; when At that time, the MPC controller is activated. The MPC controller performs rolling optimization based on the current flight state parameters and constraints, and outputs the optimal trim control surface increment. This value is then added to the previous trim value to obtain the yaw trim control quantity. until .

3. The method according to claim 1, characterized in that: The specific triggering conditions for the flattening mode are as follows: Preset flattening mode trigger threshold: height threshold Pitch angle threshold When the drone simultaneously meets and At that time, the flattening mode is triggered.

4. The method according to claim 1, characterized in that: The method for real-time planning of the rolling transition trajectory includes: When the flight status parameters trigger the preset leveling mode and the current roll angle exceeds the roll angle safety threshold, the following steps are executed: Calculate the target convergence rate based on the current roll angle and flight speed; use a polynomial trajectory planning algorithm to generate a roll transition trajectory based on the current roll angle, target roll angle, and target convergence rate; constrain the convergence trajectory according to the set allowable lateral deviation and deviation change rate thresholds; and use PID control to output roll transition trajectory control commands until the preset mode switching conditions are met, switching to attitude stability maintenance mode.

5. The method according to claim 4, characterized in that: The expression for the target convergence rate is: ； in, For the target convergence rate, , These are matching coefficients used to ensure that the convergence speed is coordinated with the flight status; V is the current roll angle; V is the flight speed; The expression for the roll transition trajectory is: ； The following boundary conditions must be met: ； Where t is time, The initial roll angle, For the target roll angle, The current roll angular velocity, and Based on the collected data, T represents the convergence time. for The derivative at time 0, for The derivative at time T; The expression for the convergence time T is: 。 6. The method according to claim 4, characterized in that: The method for constraining the convergence trajectory based on a set threshold for allowable lateral deviation and deviation change rate is as follows: Set allowable lateral deviation for: ； in, The length of the drone fuselage. The deviation matching coefficient; Set the threshold for the rate of change of deviation The allowable lateral deviation and the deviation change rate threshold are used as constraints for the MPC controller to constrain the convergence trajectory in real time, thereby limiting abrupt changes in the lateral trajectory.

7. The method according to claim 1, characterized in that: In the leveling mode, the control of aileron deflection and rudder deflection is also included. The control method for aileron deflection and rudder deflection is as follows: Based on the pre-constructed lateral and longitudinal coupled UAV dynamics prediction model, the collected current flight state parameters are used as the initial state of the prediction model to perform rolling pre-simulation of the UAV's sideslip angle dynamic response and lateral and longitudinal coupled motion trend within a preset prediction time domain, and output the prediction sequence of the sideslip angle changing with time and the prediction sequence of the lateral and longitudinal coupled motion state within a preset time period in the future. The prediction model uses the roll angle, sideslip angle, flight speed and pitch angle of the UAV as state variables, and aileron deflection and rudder deflection as control variables. With the combined optimization objectives of maximizing vertical lift recovery speed and minimizing sideslip peak, a constrained optimization equation for the control surface variables is established. The objective function of the constrained optimization equation includes a vertical lift recovery speed term and a sideslip peak term, and the vertical lift recovery speed term and the sideslip peak term are adjusted by weighting coefficients. Combining the physical amplitude limit constraint of the control surface and the rate constraint of the actuator, the optimal aileron deflection and the optimal rudder deflection for each control cycle in the prediction time domain are solved within the feasible domain of the constraint optimization equation. Based on the optimal aileron deflection and optimal rudder deflection obtained from the solution, control commands are output according to the control allocation ratio of the current control cycle.

8. The method according to claim 7, characterized in that: The parameters of the dynamic response trend of the sideslip angle include the sideslip suppression effect. ; The parameters of the lateral and longitudinal coupling motion trend include the vertical lift recovery speed. and lateral trajectory deviation ; The control surface quantity The constrained optimization equation is: ； in, The vertical lift recovery velocity is the derivative of lift with respect to time. for The weights; This refers to the sideslip suppression effect, i.e., the absolute value of the sideslip angle; For the sideslip peak term, The weights of the sideslip peak term, This is due to lateral trajectory deviation. To and Relevant weights; To the maximum allowable sideslip angle, To allow for lateral deviation; The feasible region of the constrained optimization equation is: ； ； ； in, For aileron deflection, To allow for the minimum deflection angle of the ailerons, To allow for the maximum deflection angle of the ailerons, For rudder deflection, To allow for the minimum rudder deflection angle, To allow for the maximum rudder deflection angle, To allow for the maximum deflection rate of the aileron, Maximum permissible rudder deflection rate This is the current sideslip angle; The optimal aileron deflection and optimal rudder deflection for each control cycle in the prediction time domain are solved using a sequential quadratic programming algorithm.

9. The method according to claim 1, characterized in that: In the flattening mode, the control of lateral trajectory error adopts an error relaxation and recovery mechanism, the specific method of which is as follows: Set a standard threshold for the lateral trajectory error when the flattening mode is not triggered. : ； Where L is the fuselage length; Set the relaxation threshold for the lateral trajectory error when the flattening mode is triggered. : ； in, To allow for lateral deviation; When the lateral error meets the error recovery trigger condition and the duration reaches a set time threshold, the error recovery mechanism is triggered; the error recovery mechanism is specifically as follows: The threshold for lateral trajectory error is gradually reduced using an exponential decay method until it reaches the conventional threshold for lateral trajectory error. The expression for the exponential decay method is: ； in, The attenuation coefficient is... This is the threshold for lateral trajectory error.

10. The method according to claim 9, characterized in that: The error recovery trigger condition is: ； in, This is the current roll angle; The roll angle safety threshold, For vertical lift recovery velocity, To flatten the minimum lift increase rate required, the calibration is based on the aircraft model; In the error recovery mechanism, if the following conditions are met: If the trajectory recovery is not immediately paused, the threshold for lateral trajectory error will be adjusted to the relaxation threshold.

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