UAV ground speed adaptive control method, controller and UAV

Abstract

This application discloses a method for adaptive ground speed control of a UAV, a controller, and a UAV. The control method includes: obtaining the wind speed and direction at the UAV's current altitude in real time; calculating the UAV's target true airspeed (#imgabs1#) at the current flight altitude based on the target object's ground speed (#imgabs0#) and the current wind speed and direction; and determining the UAV's ground speed adaptive strategy based on the relationship between the UAV's minimum flight true airspeed (#imgabs2#), maximum flight true airspeed (#imgabs3#), and the target true airspeed (#imgabs4#), thereby controlling the ground speed within a desired error range. The present invention can improve the UAV's ground speed adaptive capability, enhance the efficiency of target detection and tracking, and enhance the formation of the flight formation during mission execution.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicle (UAV) flight control, and more particularly to a UAV ground speed adaptive control method, a controller, and a UAV. Background Art

[0002] UAVs have a wide range of applications. When performing target tracking, forest fire prevention, resource exploration, or formation flying, they may encounter external disturbances with strong time-varying properties. This requires that the speed of the UAV relative to the target, the ground, or the aircraft in front of the formation can be adaptively adjusted according to the mission characteristics when encountering external disturbances, and the UAV must have the ability to adaptively cruise at ground speed.

[0003] Drones can detect and track specific targets in any area, including fixed or moving targets on the sea, ground, or in the air. When conducting maritime surveillance or escort missions, drones will track and identify target vessels at sea. After acquiring target information, they maintain a fixed relative position and speed relationship with the target, creating an asymmetric suppression posture. When conducting forest fire prevention or resource exploration, drones must maintain a fixed altitude and ground speed to uniformly survey the target area. To ensure consistent detection results, maintaining a constant ground speed is ideal, and improving adaptive ground speed control capabilities is essential to mitigate external interference. When flying in formation, especially in relatively tight formations, any speed adjustment by the leading aircraft requires corresponding adjustments by the following aircraft to ensure flight safety and formation alignment. The relative position between the drone and the target is determined by the ground system. The drone's speed relative to the ground is its ground speed. Whether performing mission tracking, formation flying, or ground exploration, drones must maintain adaptive ground speed capabilities. Adaptive ground speed control ensures more accurate and effective mission operations.

[0004] Currently, when performing mission tracking or ground detection, drones fly at a relatively fixed airspeed according to a pre-set track, without considering the changes in ground speed caused by changes in the external wind field; drone formation flying follows a preset track and maintains a safe distance, and all formations are of the same model, without considering the ground speed adaptation problem when manned and drones are mixed. Mission efficiency and continuity need to be improved.

[0005] Therefore, it is necessary to develop a UAV ground speed adaptive control method to improve the efficiency of target detection and tracking and the formation of UAVs when performing missions.

[0006] The information disclosed in the background technology section of the present invention is only intended to deepen the understanding of the general background technology of the present invention, and should not be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art. Summary of the Invention

[0007] The purpose of the present invention is to propose a UAV ground speed adaptive control method, a controller and a UAV, which can improve the UAV ground speed adaptive capability and improve the efficiency of target detection and tracking and formation formation when performing tasks.

[0008] Based on the above objectives, the present invention provides a method for adaptively controlling the ground speed of an unmanned aerial vehicle, comprising:

[0009] Get the wind speed and direction at the current altitude of the drone in real time;

[0010] Based on the ground speed of the target object Calculate the target true airspeed of the drone based on the current wind speed and direction

[0011] At the current flight altitude, based on the drone's minimum true airspeed Maximum true airspeed and the target true airspeed The relationship between them is used to determine the UAV ground speed adaptive strategy and control the ground speed within the expected error range.

[0012] In an optional solution, the method for determining the UAV ground speed adaptive strategy includes:

[0013] like The drone does not change its flight altitude, but adjusts its flight attitude to achieve adaptive ground speed adjustment.

[0014] like The drone climbs to a higher altitude and makes another judgment Is it true? If so, realize ground speed adaptive adjustment by adjusting the flight attitude;

[0015] like The drone lowered its flight altitude and made another judgment. Is it true? If so, adaptive ground speed adjustment is achieved by adjusting the flight attitude.

[0016] In an optional solution, the adaptive adjustment and control of ground speed using flight attitude includes:

[0017] Where ρ0 is the atmospheric density at sea level, according to the pressure height H of the UAV p and the local atmospheric density ρ, calculate the UAV target indicated airspeed V ic ,

[0018]

[0019] According to the target indicated airspeed V ic , calculate the lift coefficient Cl of the UAV,

[0020]

[0021] Among them, m represents the total weight of the UAV, g represents the acceleration of gravity, S represents the wing area of ​​the UAV, and the target flight angle of attack α of the UAV is calculated according to the lift coefficient Cl of the UAV. c , and the target flight angle α c Perform trim operations and calculate the matching thrust of the UAV to track the target indicated airspeed V ic .

[0022] In the optional solution, the drone elevator command angle is obtained according to the following formula: Then the target flight attack angle α c Perform balancing operations.

[0023]

[0024] Where q is the pitch angular rate, K q is the pitch rate control gain, α is the UAV flight attack angle, K α is the angle of attack control gain, K∫ α is the angle of attack integral control gain, It is the theoretical elevator trim angle.

[0025] In the optional solution, the calculation of the matching thrust throttle size of the drone To track the target indicated airspeed V ic include:

[0026]

[0027] Among them, V i The current flight speed of the UAV is indicated by K Vi is the indicated airspeed control gain, is the indicated airspeed integral control gain, The throttle percentage that trims the drone for the stated thrust.

[0028] In the optional solution, if the minimum ground speed of the UAV is still greater than the target ground speed after the UAV lowers its flight altitude, the UAV will perform target tracking flight in a serpentine track or circling flight.

[0029] In the optional solution, the real-time acquisition of the local wind speed and direction of the drone includes:

[0030] The ground speed and speed heading of the UAV are measured by the UAV onboard sensors to obtain the UAV flight ground speed vector Measure the true airspeed and nose heading of the drone using the onboard sensors to obtain the true airspeed vector Calculate the wind speed and direction at the current altitude of the drone using the following formula

[0031]

[0032] In the optional scheme, the minimum true airspeed is determined based on the UAV flight envelope. Maximum true airspeed

[0033] The present invention also provides a controller for implementing the above method.

[0034] The present invention also provides a drone, comprising the above-mentioned controller.

[0035] The beneficial effects of the present invention are:

[0036] The present invention uses the triangular relationship among the wind speed vector, the ground speed vector and the UAV airspeed vector as the key operation formula, performs online wind speed and direction identification according to the current flight status of the UAV, and then calculates the target true airspeed according to the ground speed of the target object and the current wind speed and direction. At the current flight altitude, based on the relationship between the UAV's minimum flight true airspeed, the maximum flight true airspeed and the target true airspeed, the UAV ground speed adaptation strategy is determined to control the ground speed within the expected error range.

[0037] The present invention adopts a ground speed adaptive strategy based on the flight envelope. Through attitude adaptive adjustment and altitude-attitude adaptive adjustment strategies, it fully utilizes the UAV's own motion characteristics and the combined three-dimensional flight space characteristics, and expands the flight range of ground speed adaptive control.

[0038] The present invention adopts a method that combines angle of attack tracking control and speed tracking control to achieve accurate tracking of the flight indicated airspeed, which can improve the anti-disturbance capability of the UAV speed tracking control, and also improves the speed control accuracy and flight control robustness of the UAV.

[0039] The ground speed adaptive control method adopted by the present invention has a wide range of applications. For long-flight UAVs, when the external wind field environment changes, the above method can also be used to perform adaptive control of the ground speed, or use wind field information to perform adaptive adjustment of altitude-attitude to achieve ground speed control.

[0040] The present invention has other features and advantages that will be apparent from or will be described in detail in the accompanying drawings and the following detailed description incorporated herein, which together serve to explain certain principles of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0042] Figure 1 A block diagram showing the principle of ground speed adaptive control of a UAV based on motion state according to an embodiment of the present invention is shown.

[0043] Figure 2 A schematic diagram of altitude-attitude adaptive adjustment of a UAV in a mission scenario according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0044] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0045] An embodiment of the present invention provides a method for adaptively controlling the ground speed of a UAV, referring to Figure 1 and Figure 2 , the method comprising:

[0046] Get the wind speed and direction at the current altitude of the drone in real time;

[0047] Based on the ground speed of the target object Calculate the target true airspeed of the drone based on the current wind speed and direction

[0048] At the current flight altitude, based on the drone's minimum true airspeed Maximum true airspeed and the target true airspeed The relationship between them is used to determine the UAV ground speed adaptive strategy and control the ground speed within the expected error range.

[0049] Specifically, the ground speed and speed heading of the UAV are measured by the UAV onboard sensor, and the UAV ground speed vector is obtained as According to the onboard sensor, the true airspeed and nose heading of the UAV are measured, and the true airspeed vector is obtained: Through the vector relationship between wind speed, ground speed and true airspeed Perform online wind speed and direction identification of the current flight status and provide the local wind speed and direction of the drone

[0050] The ground speed vector of the target object measured by airborne radar or other sensors is: The ground speed vector of the target object is also the target ground speed of the drone According to the formula of the target ground speed of the UAV and the current wind speed and direction Calculate the true airspeed of the drone target

[0051] At the current flight altitude, determine the minimum true airspeed based on the UAV's flight envelope Maximum true airspeed like The UAV does not change the flight altitude, and realizes ground speed adaptive adjustment by adjusting the flight attitude; if The drone gradually climbs to a higher altitude and determines the altitude below the current one. Is it true? If so, adjust the flight attitude to achieve ground speed adaptive adjustment. The climbing flight altitude cannot exceed the maximum altitude of the drone. When the true airspeed is still greater than the maximum flight speed after the drone climbs to the maximum altitude, report to the command and control center and request to dispatch a suitable aircraft to perform the mission. The drone lowers its flight altitude and makes another judgment at the current altitude. Is it true? If so, adaptive ground speed adjustment is achieved by adjusting the flight attitude. The flight altitude cannot be lowered below the minimum safe altitude. If the minimum ground speed of the drone is still greater than the ground speed of the target object after lowering the flight altitude, the drone will fly a serpentine track or hover to track the target.

[0052] In this embodiment, the adaptive adjustment of the flight attitude to control the ground speed includes:

[0053] Measure the drone's air pressure altitude H using the onboard air data system p , and calculate the local density ρ based on the atmospheric model, and further calculate the UAV target indicated airspeed V ic ,

[0054]

[0055] Where ρ0 is the sea level atmospheric density, according to the target indicated airspeed V ic , calculate the lift coefficient Cl of the UAV,

[0056]

[0057] m represents the weight of the drone, g represents the weight acceleration, S represents the wing area of ​​the drone, and the drone target flight angle of attack is calculated according to the drone lift coefficient Cl, and the flight angle of attack is trimmed and the matching thrust of the drone is calculated to track the target indicated airspeed V ic The target flight attack angle α of the UAV is obtained by interpolating the lift coefficient curve of the entire aircraft. cAt the same time, the UAV drag coefficient Cd is also interpolated. According to the UAV drag (required thrust) and thrust data table, the UAV trim throttle (fuel UAV) or trim speed (electric UAV) is iteratively calculated through the residual convergence method.

[0058] In this embodiment, the drone elevator command angle is obtained according to the following formula: Then, the target flight attack angle is trimmed.

[0059]

[0060] Where q is the pitch angular rate, K q is the pitch angle rate control gain, α is the UAV flight attack angle (the UAV flight attack angle α is measured in real time), K α is the angle of attack control gain, is the angle of attack integral control gain, It is the theoretical elevator trim angle.

[0061] In this embodiment, the calculation of the matching thrust throttle size δ of the drone T cmd , to track the target indicated airspeed V ic include:

[0062]

[0063] Among them, V i The current flight speed of the UAV is indicated by K Vi is the indicated airspeed control gain, is the indicated airspeed integral control gain, The throttle percentage that trims the drone for the stated thrust.

[0064] The present invention uses the triangular relationship among the wind speed vector, the ground speed vector and the UAV's airspeed vector as the key operation formula, performs online wind speed and direction identification according to the UAV's current flight status, and then calculates the true airspeed according to the ground speed of the target object and the current wind speed and direction. At the current flight altitude, based on the relationship between the UAV's minimum flight true airspeed, the maximum flight true airspeed and the target true airspeed, the UAV's ground speed adaptation strategy is determined to control the ground speed within the desired error range.

[0065] The present invention adopts a ground speed adaptive strategy based on the flight envelope. Through attitude adaptive adjustment and altitude-attitude adaptive adjustment strategies, it fully utilizes the UAV's own motion characteristics and the combined three-dimensional flight space characteristics of the UAV, and expands the flight range of ground speed adaptive control.

[0066] The present invention adopts a method that combines angle of attack tracking control and speed tracking control to achieve accurate tracking of the flight indicated airspeed, which can improve the anti-disturbance capability of the UAV speed tracking control, and also improves the speed control accuracy and flight control robustness of the UAV.

[0067] The ground speed adaptive control method adopted by the present invention has a wide range of applications. For long-flight UAVs, when the external wind field environment changes, the above method can also be used to perform adaptive control of the ground speed, or use wind field information to perform adaptive adjustment of altitude-attitude to achieve ground speed control.

[0068] Another embodiment of the present invention further provides a controller for implementing the above method.

[0069] Yet another embodiment of the present invention provides a drone, comprising the above-mentioned controller.

[0070] While various embodiments of the present invention have been described above, the above description is intended to be illustrative, not exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for adaptive ground speed control of an unmanned aerial vehicle, characterized in that: include: Get the wind speed and direction at the current altitude of the drone in real time; Based on the ground speed of the target object Calculate the target true airspeed vector of the UAV with the current wind speed and direction At the current flight altitude, based on the drone's minimum true airspeed Maximum true airspeed and the target true airspeed scalar V ac The relationship between them is used to determine the UAV ground speed adaptive strategy and control the ground speed within the expected error range. The method for determining the UAV ground speed adaptive strategy includes: like The drone does not change its flight altitude, but adjusts its flight attitude to achieve adaptive ground speed adjustment. like The drone climbs to a higher altitude and makes another judgment Is it true? If so, realize ground speed adaptive adjustment by adjusting the flight attitude; like The drone lowered its flight altitude and made another judgment. Is it true? If so, adaptive ground speed adjustment is achieved by adjusting the flight attitude.

2. The UAV ground speed adaptive control method according to claim 1, characterized in that: The adaptive adjustment of ground speed by adjusting the flight attitude includes: According to the drone's air pressure height H p and the local atmospheric density ρ, calculate the UAV target indicated airspeed V ic , Where ρ0 is the sea level atmospheric density, according to the target indicated airspeed V ic , calculate the lift coefficient Cl of the UAV, Among them, m represents the weight of the drone, g represents the acceleration of gravity, S represents the wing area of ​​the drone, and the drone target flight angle of attack α is calculated based on the drone lift coefficient Cl c , and the target flight angle α c Perform trim operations and calculate the matching thrust of the UAV to track the target indicated airspeed V ic .

3. The UAV ground speed adaptive control method according to claim 2, characterized in that: The elevator command angle of the drone is obtained according to the following formula Then the target flight attack angle α c Perform balancing operations. Where q is the pitch angular rate, K q is the pitch rate control gain, α is the UAV flight attack angle, K α is the angle of attack control gain, K ∫α is the angle of attack integral control gain, It is the theoretical elevator trim angle.

4. The UAV ground speed adaptive control method according to claim 2, characterized in that: The calculation of the matching thrust throttle size of the drone To track the target indicated airspeed V ic include: Among them, V i The current flight speed of the UAV is indicated by K Vi is the indicated airspeed control gain, K ∫Vi is the indicated airspeed integral control gain, The throttle percentage that trims the drone for the stated thrust.

5. The UAV ground speed adaptive control method according to claim 1, characterized in that: If the drone's minimum ground speed is still greater than the ground speed of the target object after the drone lowers its flight altitude, the drone will perform target tracking flight in a serpentine track or circling flight.

6. The UAV ground speed adaptive control method according to claim 1, characterized in that: The real-time acquisition of the local wind speed and direction of the drone includes: The ground speed and speed heading of the UAV are measured by the UAV onboard sensors to obtain the UAV flight ground speed vector Measure the true airspeed and nose heading of the drone using the onboard sensors to obtain the true airspeed vector Calculate the wind speed and direction at the current altitude of the drone using the following formula 7. The UAV ground speed adaptive control method according to claim 1, characterized in that: Determining the minimum true airspeed based on the UAV flight envelope Maximum true airspeed 8. A controller, characterized in that: Used to implement the method according to any one of claims 1 to 7.

9. A drone, characterized in that: Including the controller according to claim 8.

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