Multi-copter unmanned aerial vehicle assisted fixed-wing unmanned aerial vehicle landing method based on navigation vector field

Abstract

The application discloses a kind of based on navigation vector field multi-rotor unmanned aerial vehicle assisted fixed-wing unmanned aerial vehicle landing method, belong to unmanned aerial vehicle heterogeneous collaborative control technical field.This method includes: in the process of fixed-wing unmanned aerial vehicle landing, multi-rotor unmanned aerial vehicle takes off and gradually approaches fixed-wing unmanned aerial vehicle;The position, attitude and speed of the two machines are obtained by fusing real-time dynamic differential positioning and inertial measurement information, and the two machines are guided to air docking using a navigation vector field controller;Multi-rotor unmanned aerial vehicle carries fixed-wing unmanned aerial vehicle to land on the ground.The application reduces the dependence of fixed-wing unmanned aerial vehicle on the landing site by guiding and assisting the two machines to approach through path guidance and collaborative control, and carrying out landing after reliable connection.

Description

Technical Field

[0001] This invention relates to the field of heterogeneous collaborative control technology for unmanned aerial vehicles (UAVs), specifically to a method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field. Background Technology

[0002] A fixed-wing unmanned aerial vehicle (UAV) is an unmanned aircraft that employs a fixed-wing structure similar to traditional airplanes. Unlike helicopters or multi-rotor UAVs, fixed-wing UAVs generate lift through their fixed wings during flight. Due to their numerous advantages, fixed-wing UAVs are widely used in a variety of missions and environments, such as long endurance, high-speed flight, stable flight, and large payload capacity. However, the conventional runway landing method for fixed-wing UAVs typically requires a certain length of runway, limiting their application in confined spaces. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field. The method first controls the multi-rotor UAV to take off and approach the fixed-wing UAV; then, by fusing real-time dynamic differential positioning and inertial measurement information, the positions, attitudes, and velocities of both aircraft are obtained. A navigation vector field controller guides the two aircraft to perform an aerial docking; after confirming a reliable docking connection, the multi-rotor UAV carries the fixed-wing UAV to the target location, thereby reducing the dependence of the fixed-wing UAV landing on runway and site conditions.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: This invention provides a method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field, comprising: During the landing of the fixed-wing drone, the multi-rotor drone took off and gradually approached the fixed-wing drone. By fusing real-time dynamic differential positioning and inertial measurement information, the position, attitude and velocity of fixed-wing UAVs and multi-rotor UAVs are obtained. A controller is designed using navigation vector field theory to control the fixed-wing UAVs and multi-rotor UAVs to perform aerial docking. A multi-rotor drone carries a fixed-wing drone to land on the ground.

[0005] In one embodiment, the step of the multi-rotor drone taking off and gradually approaching the fixed-wing drone during the landing process of the fixed-wing drone specifically includes: Determine whether a fixed-wing UAV meets the conditions for initiating the assisted landing procedure; Determine whether a multi-rotor drone meets the takeoff conditions; Once all the above conditions are met, the multi-rotor drone takes off, and the fixed-wing drone continuously approaches the multi-rotor drone.

[0006] In one embodiment, determining whether the fixed-wing UAV meets the conditions for initiating the assisted landing procedure includes: acquiring the position and flight status of the fixed-wing UAV; when the fixed-wing UAV enters a preset rendezvous range and its flight status meets preset safety requirements, determining that the conditions for initiating the assisted landing procedure are met.

[0007] The determination of whether a multi-rotor UAV meets the takeoff conditions includes: detecting the working status of the multi-rotor UAV; when its power system and communication link are normal, its remaining energy and payload capacity meet the preset mission requirements, and the environmental conditions meet the preset safety requirements, the multi-rotor UAV is determined to meet the takeoff conditions.

[0008] In one embodiment, controlling the fixed-wing UAV and the multi-rotor UAV to perform aerial docking specifically includes: acquiring the position, attitude and speed of the two aircraft, and determining whether the preset docking control start conditions are met; after the start conditions are met, switching to the docking control algorithm to guide the docking ports of the two aircraft to approach each other; when the docking ports of the two aircraft meet the preset contact conditions, performing the docking connection operation and detecting the connection status.

[0009] In one embodiment, the preset contact condition includes: acquiring the position, attitude and speed of the docking ports of the two machines, calculating the three-axis relative position error, three-axis relative speed error and relative attitude error relative to the preset docking relationship; when the absolute value of each scalar error does not exceed the corresponding preset threshold and continues for a preset duration, it is determined that the preset contact condition is met.

[0010] In one embodiment, the multi-rotor UAV carries the fixed-wing UAV to land on the ground, specifically including: Confirm that the docking connection between the two aircraft is reliable, and test whether the combined aircraft can fly stably. Determine whether the environment and target landing area meet the preset landing requirements; When all the above conditions are met, control the combined vehicle to land at the target position.

[0011] In one embodiment, the application of navigation vector field theory to design a controller for controlling the aerial docking of a fixed-wing UAV and a multi-rotor UAV specifically includes: A dynamic model of the UAV is established, using a second-order integrator: ; in, This refers to a fixed-wing unmanned aerial vehicle (UAV). This refers to a multi-rotor drone; Let j be the position vector of the j-th UAV. for The derivative of Let j be the velocity vector of the j-th UAV. for The derivative of Let be the acceleration control variable for the j-th UAV; Introducing virtual coordinates Parametrically predetermine 3D paths and define a set of paths. : ; in, It is a four-dimensional augmented coordinate vector; , and Define the three-axis spatial coordinate variables for the path set; , and A three-axis parametric coordinate function for a predetermined path; For path parameters, and as additional virtual coordinates; For the set of real numbers, This indicates transpose.

[0012] Define path tracking error vector : ; in, , and The first A drone axis, shaft and The actual position coordinates along the axis; Represents the transpose of a vector or matrix.

[0013] Design of upper-level heterogeneous guided speed controller : ; in, These represent the path error convergence gains in the three coordinate directions. This is a unified representation of the aforementioned gain. ; These are the implicit path function errors in the three coordinate directions. This is a unified representation of the aforementioned errors; The collaborative gain of virtual path parameters; For the first Virtual path parameters for each drone; For the first The drone and the first The expected virtual path parameter offset between the drones; For the first The parameterized desired path of the UAV in the first... The component functions are defined in each coordinate direction. Therefore, the desired velocity vector and virtual path parameter update law can be extracted from the upper-level guidance controller.

[0014] Extract the desired velocity vector and virtual coordinate update law from the upper-level guidance controller: ; ; in, For drones The expected velocity vector, The update rate for its virtual path parameters. The lower-level controller uses a speed tracking control law: ; Define speed tracking error Under the conditions that the simplified model above holds true, the desired velocity is continuously differentiable, and the acceleration control variable is accurately realized, substituting the velocity tracking control law into the model yields: , when When the value is constant, the speed tracking error exponent converges to zero, causing the actual speed to approach the desired speed.

[0015] Compared with the prior art, the beneficial technical effects of the present invention are: This invention proposes an innovative composite flight control scheme aimed at solving the challenge of safe landing of fixed-wing UAVs in confined spaces. This scheme combines path guidance, cooperative control, and docking status detection, providing a technical approach for assisted landing of fixed-wing UAVs in restricted areas.

[0016] Addressing the core technological requirements of aerial docking between fixed-wing UAVs, this invention theoretically designs a dedicated docking process control method. Through path guidance, coordinated control, and docking status detection, it provides control references for the approach and docking of the two aircraft.

[0017] This invention also proposes an innovative method for landing a fixed-wing UAV carried by a multi-rotor UAV. This method enables the multi-rotor UAV to safely transport and land a fixed-wing UAV, thereby reducing the site requirements for UAV landing. This design not only improves the flexibility of landing operations but also facilitates UAV missions in confined areas. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating the landing process of a multi-rotor unmanned aerial vehicle (UAV) assisted by the present invention for a fixed-wing UAV. Figure 2 This is a schematic diagram of the landing process of a multi-rotor UAV assisting a fixed-wing UAV according to the present invention; Figure 3 This is a diagram showing the conditions for initiating the assisted landing process of the present invention. Figure 4 This is a diagram illustrating the takeoff conditions for the multi-rotor UAV of the present invention. Figure 5 This is a diagram illustrating the docking process between the multi-rotor UAV and the fixed-wing UAV of the present invention. Figure 6 This is a diagram illustrating the implementation process of the navigation vector field of the present invention; Figure 7 This is a landing judgment diagram for the combination of a multi-rotor UAV and a fixed-wing UAV of the present invention.

[0019] Figure 8 This is a flowchart of the method of the present invention. Detailed Implementation

[0020] A preferred embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] This invention addresses the problem of fixed-wing UAVs being limited by site conditions during conventional runway landings by proposing a multi-rotor UAV-assisted landing method based on navigation vector fields. By using aerial docking and combined landing, the method reduces the dependence of fixed-wing UAVs on runway landing sites.

[0022] like Figure 8 As shown, a method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field according to the present invention includes the following steps: A. During the landing of the fixed-wing drone, the multi-rotor drone takes off and gradually approaches the fixed-wing drone. B. By fusing real-time dynamic differential positioning and inertial measurement information, the position, attitude and velocity of the fixed-wing UAV and the multi-rotor UAV are obtained, and based on the above state information, the navigation vector field controller is used to guide the two aircraft to dock in the air. C. A multi-rotor drone carrying a fixed-wing drone lands on the ground.

[0023] As a further improvement of the present invention, in step A, during the landing process of the fixed-wing UAV, the multi-rotor UAV takes off and gradually approaches the fixed-wing UAV, specifically including: Step A1: Determine whether the fixed-wing UAV returning to base meets the conditions for initiating the assisted landing procedure; Step A2: The multi-rotor UAV determines whether it meets the takeoff conditions; Step A3: After both types of drones meet the conditions, the multi-rotor drone takes off, and the fixed-wing drone continuously approaches the multi-rotor drone.

[0024] In this invention, step A first determines whether the fixed-wing UAV returning to base meets the conditions for initiating the assisted landing procedure, such as... Figure 3 As shown; then determine whether the multi-rotor drone meets the takeoff conditions, such as Figure 4 As shown. When all the above conditions are met, the multi-rotor UAV takes off, and the two aircraft gradually approach each other.

[0025] In a preferred embodiment, determining whether a fixed-wing UAV meets the conditions for initiating the assisted landing procedure includes: acquiring the position and flight status of the fixed-wing UAV; when the fixed-wing UAV enters a preset rendezvous range and its flight status meets preset safety requirements, determining that the conditions for initiating the assisted landing procedure are met.

[0026] In a preferred embodiment, determining whether a multi-rotor drone meets the takeoff conditions includes: detecting the operating status of the multi-rotor drone; when its power system and communication link are normal, its remaining energy and payload capacity meet the preset mission requirements, and the environmental conditions meet the preset safety requirements, the multi-rotor drone is determined to meet the takeoff conditions.

[0027] As a further improvement of the present invention, step B, which involves fusing real-time dynamic differential positioning and inertial measurement information to obtain the position, attitude, and velocity of the fixed-wing UAV and the multi-rotor UAV, and using a navigation vector field controller to guide the two aircraft to perform aerial docking based on the aforementioned state information, specifically includes: Step B1: Obtain real-time dynamic differential positioning information and inertial measurement information of fixed-wing UAV and multi-rotor UAV respectively. Obtain the position, attitude and velocity of the two aircraft through fusion estimation. Calculate the state of the docking port of the two aircraft based on the installation relationship of the docking port relative to the aircraft body.

[0028] Step B2: Determine whether the two machines meet the preset docking control start conditions; if the conditions are met, switch to the docking control algorithm to guide the docking ports of the two machines to approach each other.

[0029] Step B3: When the docking ports of the two machines meet the preset contact conditions, perform the docking connection operation and check the connection status.

[0030] In a preferred embodiment, the preset contact conditions include: acquiring the position, attitude, and speed of the docking ports of the two machines, calculating the three-axis relative position error, three-axis relative speed error, and relative attitude error relative to the preset docking relationship; when the absolute values ​​of each component of the three-axis relative position error and the three-axis relative speed error, as well as the magnitude of the relative attitude error, do not exceed the corresponding preset thresholds, and the above conditions are continuously met for a preset duration, it is determined that the preset contact conditions are met.

[0031] In this invention, step B sequentially performs status acquisition, docking control startup judgment, port proximity, and docking connection status detection. The docking judgment process is as follows: Figure 5 As shown, the navigation vector field control process is as follows: Figure 6 As shown. Specifically, the UAV dynamics model uses a second-order integrator model to describe the UAV's motion: ,in, This refers to a fixed-wing unmanned aerial vehicle (UAV). Indicates a multi-rotor drone. For position vectors, For velocity vector, This is for acceleration control. Virtual coordinates are introduced in 3D path parameterization. Parameterized predefined path: ; Define error vector The expression for the upper-layer heterogeneous guided speed controller is: ; The aforementioned virtual path parameter coordination terms are exchanged via scalars. The docking status determination is achieved; other information required is provided by the corresponding measurement and communication modules. The desired velocity vector and virtual path parameter update law are extracted by the upper-level guidance controller. ; ; The lower-level controller uses a speed tracking control law. ,in, Let be the derivative of the desired velocity. Define the velocity tracking error. Under the conditions that the simplified model above holds true, the desired velocity is continuously differentiable, and the acceleration control variable is accurately realized, substituting the velocity tracking control law into the model yields: , when When the value is constant, the speed tracking error exponent converges to zero, causing the actual speed to approach the desired speed.

[0032] As a further improvement of the present invention, step C, in which the multi-rotor UAV carries the fixed-wing UAV to land on the ground, specifically includes: Step C1: Confirm that the docking connection between the two aircraft is reliable, and check whether the combined aircraft can fly stably; Step C2: Determine whether the environment and target landing area meet the preset landing requirements; Step C3: After the above conditions are met, control the combined vehicle to land at the target position.

[0033] In this invention, step C first confirms the reliable docking connection between the two aircraft and checks whether the combined aircraft can fly stably. Then, it determines whether the environment and target landing area meet the preset landing requirements. When all the above conditions are met, the combined aircraft is controlled to land at the target location, such as... Figure 7 As shown.

[0034] like Figure 2 As shown, when the fixed-wing UAV returns, after confirming that it meets the conditions for initiating the assisted landing process and that the multi-rotor UAV meets the conditions for takeoff, the multi-rotor UAV takes off; after meeting the conditions for initiating docking control, the ground station operator switches to the docking control program and guides the two aircraft to approach; after meeting the preset contact conditions, the docking connection operation is performed, and after confirming that the connection is reliable and the combination meets the landing requirements, the multi-rotor UAV carries the fixed-wing UAV to land at the designated location.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0036] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0037] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0038] It should be understood that although the steps in the flowcharts of the accompanying drawings are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some of the steps in the flowcharts of the accompanying drawings may include multiple steps or stages, which are not necessarily completed at the same time, but may be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but may be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.

[0039] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0041] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field, characterized in that, include: During the landing of the fixed-wing drone, the multi-rotor drone took off and gradually approached the fixed-wing drone. By fusing real-time dynamic differential positioning and inertial measurement information, the position, attitude and velocity of fixed-wing UAV and multi-rotor UAV are obtained, and based on the position, attitude and velocity of the two aircraft, the navigation vector field controller guides the two aircraft to perform aerial docking. A multi-rotor drone carries a fixed-wing drone to land on the ground.

2. The method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field according to claim 1, characterized in that, During the landing process of the fixed-wing UAV, the multi-rotor UAV takes off and gradually approaches the fixed-wing UAV, specifically including: Determine whether a fixed-wing UAV meets the conditions for initiating the assisted landing procedure; Determine whether a multi-rotor drone meets the takeoff conditions; Once all the above conditions are met, the multi-rotor drone takes off, and the fixed-wing drone continuously approaches the multi-rotor drone.

3. The method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field according to claim 2, characterized in that, The process of determining whether a fixed-wing UAV meets the conditions for initiating the assisted landing procedure includes: obtaining the position and flight status of the fixed-wing UAV; when the fixed-wing UAV enters a preset rendezvous range and the flight status of the fixed-wing UAV meets preset safety requirements, it is determined that the conditions for initiating the assisted landing procedure are met. The determination of whether a multi-rotor drone meets the takeoff conditions includes: detecting the working status of the multi-rotor drone; when the multi-rotor drone's power system and communication link are normal, the remaining energy and payload capacity meet the preset mission requirements, and the environmental conditions meet the preset safety requirements, the multi-rotor drone is determined to meet the takeoff conditions.

4. The method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field according to claim 1, characterized in that, The process of guiding the two aircraft to perform an aerial docking specifically includes: The position, attitude, and speed of the two machines are obtained to determine whether the preset docking control start conditions are met. Once the startup conditions are met, the docking control algorithm is activated to guide the docking ports of the two machines to approach each other. When the docking ports of the two machines meet the preset contact conditions, the docking connection operation is performed, and the connection status is detected.

5. The method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field according to claim 4, characterized in that, The preset contact conditions include: obtaining the position, attitude and speed of the docking ports of the two machines, calculating the three-axis relative position error, three-axis relative speed error and relative attitude error relative to the preset docking relationship; when the absolute value of each scalar error does not exceed the corresponding preset threshold and continues for a preset duration, it is determined that the preset contact conditions are met.

6. The method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field according to claim 1, characterized in that, The multi-rotor UAV carries the fixed-wing UAV to land on the ground, specifically including: Confirm that the docking connection between the two aircraft is reliable, and test whether the combined aircraft can fly stably. Determine whether the environment and target landing area meet the preset landing requirements; When all the above conditions are met, control the combined vehicle to land at the target position.

7. The method for landing a fixed-wing UAV assisted by a multi-rotor UAV based on a navigation vector field according to claim 1, characterized in that, The method of using a navigation vector field controller to guide the two aircraft to perform an in-flight docking specifically includes: A dynamic model of the UAV is established, using a second-order integrator: ； in, This refers to a fixed-wing unmanned aerial vehicle (UAV). This refers to a multi-rotor drone; Let j be the position vector of the j-th UAV. for The derivative of Let j be the velocity vector of the j-th UAV. for The derivative of Let be the acceleration control value for the j-th UAV; Introducing virtual coordinates Parametrically predetermine 3D paths and define a set of paths. : ； in, It is a four-dimensional augmented coordinate vector; These are the three-axis spatial coordinate variables that define the path set; These are the three-axis parametric coordinate functions for the predetermined path; These serve as path parameters and additional virtual coordinates, used to determine the path reference position and coordinate the movement of the two machines along the path. For the set of real numbers, Indicates transpose; Define path tracking error vector : ； in, The first The actual three-axis position coordinates of a drone; Path parameters The corresponding three-axis path reference position coordinates; Indicates transpose; Design of an upper-level heterogeneous guided speed controller : ； in, The first The path convergence gain of a UAV in three coordinate directions. This is a unified representation of the aforementioned gain. ; These represent the path tracking errors in the three coordinate directions. This is a unified representation of the aforementioned errors; The collaborative gain of virtual path parameters; For the first Virtual path parameters for each drone; The virtual path parameter interval preset for the two machines is expected to meet the following requirements. ; For the first The predetermined path is in the first Parametric coordinate functions in each coordinate direction, ; Extract the desired velocity vector and virtual coordinate update law from the upper-level guidance controller: ； ； in, For the first The expected velocity vector of the drone. The update rate for the virtual path parameters; the lower-level controller uses a speed tracking control law: ； in, For the first The speed tracking control gain of a drone is used to adjust the convergence rate of the actual speed to the desired speed; The time derivative of the desired velocity vector; Define speed tracking error Under the conditions that the simplified model above holds true, the desired velocity is continuously differentiable, and the acceleration control quantity is accurately realized, substituting the velocity tracking control law into the model yields: ； when When the value is constant, the speed tracking error exponent converges to zero, causing the actual speed to approach the desired speed.

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