A method, system and device for aerial docking of fixed-wing unmanned aerial vehicles

Abstract

This invention discloses a method and device for mid-air docking of fixed-wing UAVs. The method comprises: obtaining the position and attitude information of the UAVs; calculating the current UAV docking trajectory based on the positional relationship between the target UAV and the docking UAV; and outputting instructions based on input from a flight controller. The method integrates mission planning, trajectory design, and multi-sensor information fusion to achieve mid-air docking of fixed-wing UAVs, further diversifying the use of UAVs.

Description

Technical Field

[0001] The invention discloses a method and a device for aerial docking of fixed-wing UAVs, which enable the fixed-wing UAVs to dock with each other in the air. Background Art

[0002] Drones have been widely used in military, agriculture, logistics, electricity and other fields. In addition to improving the performance of single machines, countries are also vigorously developing autonomous drone technology. The technology of autonomous drone docking and recovery on land, sea and air is constantly developing to meet the needs of future drone clusters.

[0003] UAV docking methods and requirements vary depending on the landing platform environment. In existing research, the Chinese invention application "A Method for Autonomous Aerial Docking of UAVs Based on Binocular Stereo Vision" (publication number: CN116860000A, publication date: October 10, 2023) uses a trajectory planning method based on model predictive control to construct a docking control method based on a PID-disturbance observer, achieving trajectory planning for fixed-wing UAV aerial docking. The Chinese invention application "A Method for Precise Docking Control of Aerial Recovery of Fixed-wing UAVs Based on Direct Force Control" (publication number: CN117170409A, publication date: December 5, 2023) uses direct force control to select an appropriate control surface combination to maintain the UAV's pitch attitude and establish a vertical translation mode, enabling aerial docking and recovery of fixed-wing UAVs. China's invention application "Precision docking control method and system for the aerial charging mother-child aircraft of a quadcopter UAV" (publication number: CN113900453A, publication date: January 7, 2022) obtains horizontal position information through a visual processing module and altitude information through a laser rangefinder, which are respectively transmitted to the horizontal position controller and altitude controller to control the quadcopter UAV to land precisely. Summary of the Invention

[0004] Purpose of the invention: The present invention discloses a method and device for the aerial docking of fixed-wing UAVs. The provided method integrates mission planning, trajectory design, and multi-sensor information fusion to achieve the docking of fixed-wing UAVs in the air, making the use of UAVs more diversified.

[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0006] In a first aspect, a method for mid-air docking of a fixed-wing UAV is provided. When the horizontal coordinate error between the UAV and the mobile platform is within a preset range, a docking and recovery mission is performed. During the docking and recovery mission, only the vertical position and attitude of the UAV and the mobile platform are adjusted:

[0007] At time t, the drone moves in the vertical direction at an exponential function The form is close to the mobile platform, and the horizontal speed change curve of the UAV during the landing mission is designed. , and restrict the drone docking area terminals ,y u is the coordinate of the UAV in the y-axis direction in the earth coordinate system during the docking and recovery mission, f0 is the coordinate of the mobile platform relative to the UAV body coordinate system in the y-axis direction at the initial moment of the docking and recovery mission, Δy is the height difference between the UAV and the mobile platform during the docking and recovery mission in the new coordinate system, Δx is the horizontal distance between the UAV and the mobile platform during the docking and recovery mission in the new coordinate system, Δx0 is the horizontal distance between the UAV and the mobile platform at the initial moment of the docking and recovery mission in the new coordinate system, θ is the angle between the mobile platform speed and the ground, and v ux is the speed of the UAV in the x-axis direction in the geodetic coordinate system during the docking and recovery mission, v ux0 At the initial moment of the docking and recovery mission, the UAV is in the geodetic coordinate system. x Speed ​​in the direction, k h is the height adjustment parameter, k v is the speed adjustment parameter, u fy k is the velocity of the mobile platform relative to the UAV body in the y-axis direction during the docking and recovery mission, r is the task time parameter, x f x is the coordinate of the mobile platform relative to the UAV body in the x-axis direction during the docking and recovery mission. u It is the x-axis coordinate of the UAV in the geodetic coordinate system during the docking and recovery mission.

[0008] As a preferred solution of the present invention, the control quantity of the UAV at any time during the docking and recovery mission is:

[0009] UAV thrust , track angle ,in, is the resistance of the drone, v fx The speed of the mobile platform relative to the UAV body coordinate system in the x-axis direction during the docking and recovery mission;

[0010] Design throttle change rate control rate ,in, is the proportional gain of the throttle control system, is the integral gain of the throttle control system, is the actual aircraft thrust, is the compensation coefficient of throttle delay, s is a complex variable;

[0011] The pitch angle of the drone is consistent with the mobile platform, and the following control rates are adopted for the drone's elevation, rudder and deflection angles. ,in, To calculate the pitch rate of the UAV, is the actual UAV pitch rate, is the pitch acceleration of the UAV, is the proportional gain of the UAV’s pitch angular velocity control system, is the integral gain of the UAV’s pitch angular velocity control system, is the proportional gain of the pitch angle control system of the UAV.

[0012] As a preferred solution of the present invention, the height adjustment parameter k h The expression is: , where The relative height threshold between the UAV and the mobile platform is the threshold when the UAV and the mobile platform meet the conditions for successful docking. Δy0 is the height difference between the UAV and the mobile platform at the initial moment of the docking recovery mission, and y f0 It is the coordinate of the mobile platform relative to the UAV body in the y-axis direction at the initial moment of the docking and recovery mission.

[0013] As a preferred solution of the present invention, the speed adjustment parameter k v The expression is: , where The minimum speed of the drone to meet the conditions for successful docking between the drone and the mobile platform. The minimum pitch angle of the drone when the drone and the mobile platform meet the conditions for successful docking, u uy0 is the velocity of the UAV in the y-axis direction in the geodetic coordinate system at the initial moment of the docking and recovery mission.

[0014] Secondly, a fixed-wing UAV aerial docking system is also provided, comprising:

[0015] A state perception module is used to obtain state information of the UAV and the mobile platform, wherein the state information includes at least the speed and position of the UAV and the speed and position of the mobile platform;

[0016] Data storage module, used to store historical and real-time status information of the UAV and docking platform;

[0017] A trajectory planning module, used to plan the UAV docking trajectory according to the method described in step (3) above;

[0018] The flight control module is used to calculate the control amount of the UAV in the trajectory planned by the trajectory planning module according to the method described in step (4) above.

[0019] In a third aspect, an electronic device is also provided, comprising one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing the method described above.

[0020] In a fourth aspect, a computer-readable storage medium storing one or more programs is also provided, wherein the one or more programs include instructions, which, when executed by a computing device, cause the computing device to perform the method as described above.

[0021] Beneficial effects: The method of the present invention extends the landing of fixed-wing UAVs in a fixed area to exponential landing of mobile targets, and decouples the mission trajectory according to flight control, realizing the combination of trajectory planning and flight control, making the UAV control smoother, and can be applied to fixed-wing UAVs without flaps. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of a method according to an embodiment of the present invention.

[0023] Figure 2 2 is a schematic diagram of UAV docking according to an embodiment of the present invention.

[0024] Figure 3 It is a structural schematic diagram of a docking device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 As shown, an embodiment of the present invention discloses a method for aerial docking of a fixed-wing UAV, comprising the following steps:

[0027] (1) Obtain the position and attitude information of the UAV and mobile platform.

[0028] When the horizontal coordinate error between the UAV and the mobile platform is within a preset range (set to 0.5~1m in this embodiment), the docking recovery mission is performed, and during the docking recovery mission, only the vertical position and attitude of the UAV and the mobile platform are adjusted, and the initial moment of the docking recovery mission and the position and attitude of the UAV and the mobile platform during the docking recovery mission are obtained, including the velocity of the UAV in the geodetic coordinate system at the initial moment of the docking recovery mission. =[v ux0 u uy0 ],Location =[ x u0 y u0] and the speed of the mobile platform relative to the drone body coordinate system =[x f0 y f0 ] and location =[v fx0 u fy0 ], the speed of the UAV in the geodetic coordinate system during the docking and recovery mission and location And the position of the mobile platform relative to the drone body coordinate system and speed ; Among them, v ux0 、u uy0 is the velocity of the UAV in the x and y axis directions in the geodetic coordinate system at the initial moment of the docking recovery mission, x u0 、y u0 is the x-axis and y-axis coordinates of the UAV in the geodetic coordinate system at the initial moment of the docking and recovery mission, v fx0 、u fy0 is the velocity of the mobile platform relative to the UAV body coordinate system in the x and y axes at the initial moment of the docking recovery mission, f0 、y f0 v is the x-axis and y-axis coordinates of the mobile platform relative to the UAV body coordinate system at the initial moment of the docking recovery mission, ux 、u uy is the speed of the UAV in the x and y axis directions in the geodetic coordinate system during the docking and recovery mission, x u 、y u v is the x-axis and y-axis coordinates of the UAV in the geodetic coordinate system during the docking and recovery mission, fx 、u fy is the speed of the mobile platform relative to the UAV body in the x and y axis coordinate system during the docking and recovery mission, x f 、y f It is the coordinates of the mobile platform in the x-axis and y-axis directions relative to the UAV body coordinate system during the docking and recovery mission.

[0029] Specifically, the location information of the UAV and the mobile platform can be obtained through GPS, accelerometers, and visual sensors.

[0030] (2) Convert the coordinate systems of the drone and the mobile platform.

[0031] In this embodiment, the angle between the speed of the mobile platform and the ground is obtained as , the original UAV coordinate system vector is converted into Rotation, the rotation matrix is , get the new coordinates of the drone and mobile platform , , , ,in, 、 、 、 It is the new coordinate and speed information of the UAV and mobile platform in the new coordinate system. 、 、 、 It is the coordinates of the UAV and mobile platform in the original geodetic coordinate system.

[0032] (3) Calculate the UAV docking trajectory based on dynamic exponential landing.

[0033] Specifically, the horizontal distance between the drone and the mobile platform As the dependent variable, the mission initial horizontal interval between the UAV and the mobile platform , the height of the drone is an exponential function Approach the mobile platform in the form of a drone docking area terminal , where the height adjustment parameter , speed adjustment parameters , is the expected height of the trajectory of the UAV in its current state, is the initial flight height of the mobile platform, is the height difference between the drone and the mobile platform at the current moment, The height difference between the drone and the mobile platform at the initial moment. Design the horizontal speed change curve relative to the mobile platform ,in is the task time parameter (constant parameter, the default value can be set to 15, 20, 25), and the result is as follows Figure 2 The drone trajectory is shown.

[0034] (4) Calculate the control quantity of the UAV on this trajectory.

[0035] The track angle at any time is , UAV thrust ,in The drone is subject to resistance because the drone's thrust has a certain error due to the change in speed. Considering the throttle response delay, the throttle is integrated to obtain the throttle control rate. ,in is the actual aircraft thrust. During this process, the pitch angle of the drone is consistent with the mobile platform, and the following control rate is adopted for the drone's elevator rudder angle ,in, To calculate the pitch rate of the UAV, is the actual UAV pitch rate, is the pitch acceleration of the UAV, is the proportional gain of the UAV’s pitch angular velocity control system, is the integral gain of the UAV’s pitch angular velocity control system, is the proportional gain of the pitch angle control system of the UAV.

[0036] The present invention will be further described below based on data from an experiment.

[0037] Experimental example: A UAV and a mobile platform are about to perform a docking and recovery mission. The situation of the UAV and the mobile platform is as follows: Figure 3 As shown, the weight of the drone is 3kg and the wingspan is 0.328m / s 2 , the air density is 1.29kg / m 3 , the drag coefficient is 0.08, and the information of the UAV and mobile platform at a certain time after the docking and recovery mission begins is shown in Table 1:

[0038] Table 1

[0039]

[0040] The following will use a fixed-wing UAV docking method proposed in this method to calculate the trajectory and control quantity of the UAV at the next moment:

[0041] (1) When the angle between the speed of the mobile platform and the ground is , the original target UAV coordinate system vector is Rotation, the rotation matrix is , get the new coordinates of the drone and mobile platform , , , .in, 、 、 、 It is the new coordinate and speed information of the unmanned and mobile platforms in the new coordinate system. 、 、 、 It is the coordinates of the UAV and mobile platform in the original geodetic coordinate system.

[0042] (2) Based on the information provided in the above figure, it is assumed that the drone needs to be above the mobile platform To complete the docking task, it is estimated that Mission accomplished. Height adjustment parameters , speed adjustment parameters , then the altitude of the UAV is expected to be 0.1s later

[0043] ; The speed of the drone at this time is

[0044] .

[0045] (3) The track angle at 0.1s from the start of the mission is

[0046] ;

[0047] At this time, the thrust of the drone is

[0048] .

[0049] like Figure 3 As shown, an embodiment of the present invention discloses a fixed-wing UAV aerial docking device, comprising: a UAV state perception module, a data storage module, a trajectory planning module, and a flight control module. The UAV state perception module includes a UAV self-perception unit, a mobile platform perception unit, and a unit for respectively obtaining the UAV's speed and position data and the mobile platform's speed and position data. The data storage module includes a historical data unit and a real-time data unit for storing historical and real-time flight data, respectively. The trajectory planning module performs trajectory planning based on the UAV state perception module and the requirements of the exponential landing method. The flight control module calculates the control quantity of the docking UAV on this docking trajectory based on the landing mission requirements of the mobile platform.

[0050] The fixed-wing UAV aerial docking device disclosed in this embodiment and the fixed-wing UAV aerial docking determination method embodiment belong to the same concept. The specific implementation process is detailed in the method embodiment and will not be repeated here.

[0051] Based on the same technical solution, the present invention also discloses a computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, which, when executed by a computing device, enable the computing device to execute the above-mentioned fixed-wing UAV aerial docking method.

[0052] Based on the same technical solution, the present invention also discloses an electronic device, including one or more processors, one or more memories and one or more programs, wherein the one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing the above-mentioned fixed-wing UAV aerial docking method.

[0053] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0054] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0055] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0056] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0057] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for aerial docking of a fixed-wing UAV, characterized in that: When the horizontal coordinate error between the drone and the mobile platform is within the preset range, the docking and recovery mission is performed. During the docking and recovery mission, only the vertical position and attitude of the drone and the mobile platform are adjusted: At time t, the drone moves in the vertical direction at an exponential function The form is close to the mobile platform, and the horizontal speed change curve of the UAV landing mission is designed. , and restrict the drone docking area terminals , y u is the coordinate of the UAV in the y-axis direction in the earth coordinate system during the docking and recovery mission, f0 is the coordinate of the mobile platform relative to the UAV body coordinate system in the y-axis direction at the initial moment of the docking and recovery mission, Δy is the height difference between the UAV and the mobile platform during the docking and recovery mission in the new coordinate system, Δx is the horizontal distance between the UAV and the mobile platform during the docking and recovery mission in the new coordinate system, Δx0 is the horizontal distance between the UAV and the mobile platform at the initial moment of the docking and recovery mission in the new coordinate system, θ is the angle between the mobile platform speed and the ground, and v ux is the speed of the UAV in the x-axis direction in the geodetic coordinate system during the docking and recovery mission, v ux0 At the initial moment of the docking and recovery mission, the UAV is in the geodetic coordinate system. x Speed ​​in the direction, k h is the height adjustment parameter, k v is the speed adjustment parameter, u fy k is the velocity of the mobile platform relative to the UAV body in the y-axis direction during the docking and recovery mission, r is the task time parameter, x f x is the coordinate of the mobile platform relative to the UAV body in the x-axis direction during the docking and recovery mission. u is the x-axis coordinate of the UAV in the geodetic coordinate system during the docking and recovery mission. The relative height threshold between the UAV and the mobile platform is used to meet the conditions for successful docking between the UAV and the mobile platform. u fy0 The coordinate system of the mobile platform relative to the UAV body at the initial moment of the docking recovery mission y Speed ​​in the axis direction.

2. The method according to claim 1, characterized in that The coordinate systems of the UAV and the mobile platform are rotated by the angle θ between the mobile platform speed and the ground to obtain a new coordinate system.

3. The method according to claim 2, characterized in that Rotation Matrix .

4. The method according to claim 1, wherein The control quantity of the UAV at any time during the docking and recovery mission is: UAV thrust , track angle ,in, is the resistance of the drone, v fx The speed of the mobile platform relative to the UAV body coordinate system in the x-axis direction during the docking and recovery mission; Design throttle change rate control rate ,in, is the proportional gain of the throttle control system, is the integral gain of the throttle control system, is the actual aircraft thrust, is the compensation coefficient of throttle delay, s is a complex variable; The pitch angle of the drone is consistent with the mobile platform, and the following control rates are adopted for the drone's elevation, rudder and deflection angles. ,in, To calculate the pitch rate of the UAV, is the actual UAV pitch rate, is the pitch acceleration of the UAV, is the proportional gain of the UAV’s pitch angular velocity control system, is the integral gain of the UAV’s pitch angular velocity control system, is the proportional gain of the pitch angle control system of the UAV.

5. The method according to claim 1, wherein Height adjustment parameter k h The expression is: , where The relative height threshold between the UAV and the mobile platform is the threshold when the UAV and the mobile platform meet the conditions for successful docking. Δy0 is the height difference between the UAV and the mobile platform at the initial moment of the docking recovery mission, and y f0 It is the coordinate of the mobile platform relative to the UAV body in the y-axis direction at the initial moment of the docking and recovery mission.

6. The method according to claim 1, characterized in that Speed ​​adjustment parameter k v The expression is: , where The minimum speed of the drone to meet the conditions for successful docking between the drone and the mobile platform. The minimum pitch angle of the drone when the drone and the mobile platform meet the conditions for successful docking, v uy0 is the velocity of the UAV in the y-axis direction in the geodetic coordinate system at the initial moment of the docking and recovery mission.

7. An electronic device, characterized in that: The method comprises one or more processors, one or more memories, and one or more programs, wherein the one or more programs are stored in the one or more memories and are configured to be executed by the one or more processors, and the one or more programs include instructions for executing the method according to any one of claims 1 to 6.

8. A computer-readable storage medium storing one or more programs, wherein the one or more programs include instructions, characterized in that: When the instructions are executed by a computing device, the computing device is caused to perform the method according to any one of claims 1 to 6.

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