A multi-machine coordinated UAV aerial recovery and release system and method

Abstract

The present invention discloses a multi-machine coordinated aerial recovery and release system for unmanned aerial vehicles and a method thereof. The system includes an aerial recovery mother machine, a first hanging unmanned aerial vehicle, a second hanging unmanned aerial vehicle and a fixed-wing unmanned aerial vehicle, the first hanging unmanned aerial vehicle and the second hanging unmanned aerial vehicle are symmetrically arranged below the aerial recovery mother machine; the aerial recovery mother machine includes a mother machine body, a winding device and a locking device are arranged below the mother machine fuselage, the winding device is used to retract and release ropes, and the aerial recovery mother machine supplies power and sends instructions to the first hanging unmanned aerial vehicle and the second hanging unmanned aerial vehicle through cables; the first hanging unmanned aerial vehicle and the second hanging unmanned aerial vehicle both include a unmanned aerial vehicle body, a guide hole is provided at the center of gravity position of the unmanned aerial vehicle body, the guide hole is used for the rope to pass through, a support plate is provided on the top of the unmanned aerial vehicle body, the support plate is used to clamp the wing of the fixed-wing unmanned aerial vehicle when the aerial capture is completed, and an electromagnet is provided at the rear of the support plate, the electromagnet is used to engage and fix with the locking device when the recovery is completed.

Description

Technical Field

[0001] The present invention relates to the technical field of unmanned aerial vehicles (UAVs), and more particularly to a multi-machine coordinated UAV aerial recovery and release system and method thereof. Background Art

[0002] With the continuous advancement of intelligent and unmanned technology, more and more application scenarios require drones to have the ability to automatically take off and land, cruise and perform tasks.

[0003] Existing technologies for the aerial recovery and release of fixed-wing UAVs have certain defects. For example, the use of skyhook recovery requires manual participation to remove the UAV, and the impact after the UAV hits the hook is large, which can easily cause structural damage; the use of aerial refueling mode is difficult to align the UAV because the end of the towline pendant is uncontrollable; the use of multi-rotor aerial airports can only accept UAVs with vertical take-off and landing functions, which is not very practical; the use of aerial runway-type fixed-wing dual-aircraft hard docking recovery method has very high control accuracy requirements, limited wind interference resistance, and is prone to collision accidents.

[0004] Therefore, how to provide a drone aerial recovery and release system and method that can solve the above-mentioned technical problems is an issue that technical personnel in this field urgently need to solve. Summary of the Invention

[0005] In view of this, the present invention provides a multi-machine coordinated drone aerial recovery and release system and method, which can be applied to future aerospace carriers and ship-borne drones. After appropriate expansion, it can also be used to capture non-cooperative aerial targets, such as enemy fixed-wing drones.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A multi-machine coordinated UAV aerial recovery and release system includes an aerial recovery mother aircraft, a first hanging UAV, a second hanging UAV, and a fixed-wing UAV, wherein the first hanging UAV and the second hanging UAV are symmetrically arranged below the aerial recovery mother aircraft;

[0008] The aerial recovery mother machine includes a mother machine fuselage, a winding device and a locking device arranged below the mother machine fuselage, the winding device is used to retract and release ropes and cables, the aerial recovery mother machine supplies power and sends instructions to the first hanging drone and the second hanging drone through the cable, and retracts and releases the first hanging drone and the second hanging drone through the rope;

[0009] The first hanging drone and the second hanging drone both include a drone body, a guide hole is provided at the center of gravity of the drone body, the guide hole is used for the rope to pass through, a support plate is provided on the top of the drone body, the support plate is used to clamp the wings of the fixed-wing drone when the aerial capture is completed, and an electromagnet is provided at the rear of the support plate, which is used to engage and fix with a locking device when the recovery is completed.

[0010] Preferably, the first hanging drone and the second hanging drone each further include a magnetic buckle;

[0011] The first hanging drone also includes a groove, the groove being located below the guide hole;

[0012] The second hanging drone also includes a boss, which is located below the guide hole;

[0013] The grooves and bosses are adapted to each other, and the magnetic buckle is used to achieve suction and fixation when the capture in the air is completed.

[0014] Preferably, the rope and the cable are twisted into one strand within the winding device.

[0015] Preferably, the winding device includes a winding motor, a core shaft, a rolling bearing and an electrical connection plug, wherein both ends of the core shaft are supported by rolling bearings and both ends of the rolling bearings are fixed to the mother machine body, the middle part of the core shaft is driven by the winding motor, and the winding motor is fixed to the mother machine body through a base;

[0016] The aerial recovery mother aircraft also includes a power supply and data interface;

[0017] The rope suspends the first hanging UAV and the second hanging UAV to the bottom of the aerial recovery mother machine through the guide hole, and both ends of the rope and cable are connected to the power supply data interface through electrical connection plugs.

[0018] 5. The multi-machine coordinated UAV aerial recovery and release system according to claim 1 is characterized in that the rear tilting angle of the support plate is greater than the front tilting angle of the support plate.

[0019] A multi-machine coordinated UAV aerial recovery and release method includes: aerial recovery and aerial release processes;

[0020] The aerial recovery process includes:

[0021] S101: When the aerial recovery mother aircraft detects the fixed-wing UAV, it controls the winding device to release the entire length of the rope and cable. After receiving the control command, the first and second hanging UAVs extend the ropes through the guide holes. The aerial recovery mother aircraft, the first and second hanging UAVs coordinately control the center of the rope loop to align with the nose of the fixed-wing UAV, and wait for the fixed-wing UAV to enter the rope loop.

[0022] S102: The aerial recovery mother aircraft detects that the nose of the fixed-wing UAV has entered the rope loop. The aerial recovery mother aircraft sends a control command to the first and second hanging UAVs via the cable. After receiving the control command, the first and second hanging UAVs move closer to each other while maintaining a horizontal attitude. The aerial recovery mother aircraft reclaims the rope and cable.

[0023] S103: The fixed-wing UAV descends under the control of the coordinated command until both wings of the fixed-wing UAV touch the support plate, completing the aerial capture and the fixed-wing UAV stops operating;

[0024] S104: The aerial recovery mother aircraft continues to recover the ropes and cables. The first and second hanging drones maintain a horizontal posture using their own power to support the fixed-wing drone. The fixed-wing drone is retracted to the bottom of the aerial recovery mother aircraft. The locking device engages the electromagnet, and the recovery is complete.

[0025] The aerial release process includes:

[0026] S201: The aerial recovery mother aircraft and the fixed-wing UAV accelerate forward as a whole. When the release speed is reached, the aerial recovery mother aircraft sends a power-off command to the first and second hanging UAVs via a cable. After receiving the power-off command, the electromagnets on the first and second hanging UAVs are powered off, causing the electromagnets to disengage from the locking devices.

[0027] S202: The aerial recovery mother aircraft controls the winding device to release the rope and cable. The first and second hanging drones remain horizontal and support the fixed-wing drone, and are lowered to the lowest point along the ropes together with the fixed-wing drone.

[0028] S203: After the aerial recovery mother aircraft controls the winding device to release all the ropes, the first and second hanging drones receive control commands and roll and pitch around their own body axes, respectively, to the left and right, thereby opening the rope loops. Simultaneously, as the pitch angle gradually increases, the pallet gradually separates from the fixed-wing drone's wings.

[0029] S204: The forward component force generated by the change in the pitch angle of the first hanging UAV and the second hanging UAV pulls the rope loop forward, and at the same time, the aerial recovery mother aircraft accelerates forward, and the fixed-wing UAV slides out of the rope loop backward, completing the aerial release.

[0030] Preferably, the aerial recovery process S103 further includes:

[0031] The fixed-wing drone descends under the control of the coordinated command until the wings on both sides of the fixed-wing drone touch the support plate. Then, the grooves and bosses cooperate and the first hanging drone and the second hanging drone are attracted together through the magnetic buckle, completing the aerial capture.

[0032] The aerial release process also includes:

[0033] S205: The fixed-wing UAV's own power system is activated to generate thrust to continue horizontal flight, and the mother aircraft is recovered in the air to retract the ropes and cables.

[0034] Preferably, the control instruction is: the aerial recovery mother aircraft will move the desired relative position [x r y r z r ] is sent as a control instruction to the first hanging UAV and the second hanging UAV through the cable. The first hanging UAV and the second hanging UAV generate electrical control instructions for the motor and the servo through the position control loop and the attitude control loop according to the control instruction of the aerial recovery mother aircraft. Specifically:

[0035] Position control loop includes: Position deviation through P xzy The module generates the desired speed V d , expected speed V d By PID V The module generates the expected acceleration A d (a xd ,a yd ,a zd ), the expected acceleration A d (a xd ,a yd ,a zd ) into the dynamic model to solve for the desired roll angle φ d and the desired pitch angle θ d ;

[0036] The attitude control loop consists of: d , desired pitch angle θ d and the model predicts the feedforward settlement equilibrium roll angle φ trim The superposition is used as the desired attitude angle, and the desired attitude angle is obtained by P Θ The module obtains the desired attitude angular rate ω d , attitude angular rate ω d By PID ω The module obtains the desired torque τ d .

[0037] Preferably, the desired roll angle φ d and the desired pitch angle θ d The calculation formula is:

[0038] φ d =k φ a yd

[0039] θ d=k θ a xd

[0040] Among them, k φ Indicates the roll scale coefficient, k θ Indicates the pitch scale coefficient, a yd represents the desired acceleration in the y direction, a xd represents the desired acceleration in the x direction;

[0041] Balanced roll angle φ trim The calculation formula is:

[0042]

[0043] Where m is the mass of the first or second hanging drone, g is the acceleration of gravity, T prop represents the propeller thrust, γ represents the rope loop expansion angle, y r1 Indicates the expected relative position of the first suspended UAV in the y direction, y r2 Indicates the expected relative position of the second suspended UAV in the y direction.

[0044] Preferably, the maximum opening angle γ of the rope loop max for:

[0045]

[0046] Where m is the mass of the first or second hanging drone, g is the acceleration of gravity, T pmax The maximum thrust generated by the propeller.

[0047] The present invention has the following advantages:

[0048] 1) A retractable rope is used, with the first and second hanging drones at the ends, forming three nodes with the aerial recovery motherboard. The position can be adjusted in the air so that the rope loop is aligned with the drone to be captured.

[0049] 2) Because the rope is flexible and the aerial recovery aircraft can maintain a speed similar to that of the fixed-wing UAV to be captured, the impact load during the capture process is smaller, which is beneficial to reducing the weight of the UAV structure.

[0050] 3) Fixed-wing UAVs do not need to be equipped with landing gear or recovery devices. After being recovered in the air, they can take off and land vertically together with the mother aircraft, saving a lot of weight that is not effective for cruise missions and greatly increasing the cruising range of small fixed-wing UAVs.

[0051] 4) Using this solution to recover fixed-wing drones from the air can solve the problem of take-off and landing of carrier-based aircraft in high sea conditions, allowing small ships such as destroyers and cruisers to take off and land fixed-wing drones. Moreover, since the aerial recovery mother aircraft does not need to consider the issue of cruising range, the power can be designed to be very sufficient, enough to withstand the interference of strong winds of level 7-8, and realize vertical take-off and landing of the aerial recovery mother aircraft with fixed-wing drones.

[0052] 5) The air release of the fixed-wing UAV can be completed by reversing the recovery steps, solving the problem of fixed-wing catapult launch devices occupying very valuable ship deck space.

[0053] 6) No human intervention is required during the take-off, landing, and recovery processes. The mother aircraft can automatically perform multiple rounds of flight missions, which improves the efficiency of fixed-wing UAV use and provides a reliable guarantee for the execution of swarm UAV missions.

[0054] 7) Fixed-wing drones can be captured without installing any special equipment, and the rope loop at the controllable end has the ability to automatically align with the drone to be captured, allowing for non-destructive aerial capture of non-cooperative drones.

[0055] 8) For the fixed-wing UAV to be recovered, there is no need to maintain a close position with the mother aircraft for a long time while keeping the same speed, magnitude, and direction. As long as the flight path is controlled through the rope loop, aerial capture and recovery can be completed. A certain tolerance is allowed for the left and right and up and down position of the fixed-wing UAV, and there are no strict requirements for speed and direction. This reduces the difficulty of controlling the UAV during recovery, improves the ability to resist uncertain external interference, reduces the time the two aircraft fly together, and improves recovery efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0057] Figure 1 The accompanying drawing is a schematic structural diagram of a multi-machine coordinated UAV aerial recovery and release system provided by the present invention.

[0058] Figure 2 The accompanying drawing is a schematic structural diagram of the first suspended UAV provided by the present invention.

[0059] Figure 3 The accompanying drawing is a schematic structural diagram of the second suspended UAV provided by the present invention.

[0060] Figure 4The accompanying drawings are schematic diagrams of the first hanging UAV and the first hanging UAV combination hanging provided by the present invention.

[0061] Figure 5 The accompanying drawing is a schematic structural diagram of the winding device provided by the present invention.

[0062] Figure 6 The accompanying drawing is a flow chart of the aerial recovery provided by the present invention.

[0063] Figure 7 The accompanying drawing is a flow chart of the aerial release provided by the present invention.

[0064] Figure 8 The accompanying drawing is a flow chart of position and posture control provided by the present invention.

[0065] Figure 9 The accompanying drawing is a schematic diagram of the aerial recovery process provided by the present invention.

[0066] Figure 10 The accompanying drawing is a schematic diagram of the air capture state provided by the present invention.

[0067] Figure 11 The accompanying drawing is a schematic diagram of the recycling state provided by the present invention.

[0068] Figure 12 The accompanying figure is a schematic diagram of the actual roll angle of the suspended UAV provided by the present invention.

[0069] Figure 13 The accompanying drawing is a schematic diagram of the rope expansion angle provided by the present invention.

[0070] Among them, 1. Aerial recovery mother machine, 101. Rope, 102. Winding device, 1021. Winding motor, 1022. Core shaft, 1023. Rolling bearing, 1024. Electrical connection plug, 103. Power supply data interface, 104. Cable, 2. First hanging UAV, 3. Second hanging UAV, 4. Fixed-wing UAV, 5. UAV fuselage, 6. Guide hole, 7. Support plate, 8. Electromagnet, 9. Groove, 10. Boss, 11. Magnetic buckle, 12. Brushless motor, 13. Tilt mechanism. DETAILED DESCRIPTION

[0071] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0072] The embodiment of the present invention discloses a multi-machine coordinated UAV aerial recovery and release system, such as Figure 1-4As shown, it includes: an aerial recovery mother machine 1, a first hanging drone 2, a second hanging drone 3 and a fixed-wing drone 4. The first hanging drone 2 and the second hanging drone 3 are symmetrically arranged below the aerial recovery mother machine 1. The first hanging drone 2 and the second hanging drone 3 can independently control the four degrees of freedom of pitch, roll, yaw and vertical descent, so as to control the rope loop to open and close in the air and move left and right and forward and backward, so that the rope loop can automatically align with the fixed-wing drone to be captured;

[0073] The aerial recovery mother machine 1 includes a mother machine fuselage, and a winding device 102 and a locking device are arranged below the mother machine fuselage. The winding device 102 and the locking device are arranged below the mother machine fuselage to reduce resistance during flight. The winding device 102 is used to retract and release the rope 101 and the cable 104. The aerial recovery mother machine 1 supplies power and sends instructions to the first hanging drone 2 and the second hanging drone 3 through the cable 104, and retracts and releases the first hanging drone and the second hanging drone through the rope;

[0074] The first hanging drone 1 and the second hanging drone 3 both include a drone body 5, and a guide hole 6 is provided at the center of gravity of the drone body 5, and the guide hole 6 is used for the rope to pass through. A support plate 7 is provided on the top of the drone body 5, and the support plate 7 is used to clamp the wings of the fixed-wing drone 4 when the aerial capture is completed. An electromagnet 8 is provided at the rear of the support plate 7, and the electromagnet 8 is used to engage and fix with the locking device when the recovery is completed.

[0075] The aerial recovery mother aircraft 1 can be a multi-rotor, fixed-wing, helicopter, or other type of aircraft. The first hanging drone 2 and the second hanging drone 3 can be dual-rotor or other types. At the same time, the first hanging drone 2 and the second hanging drone 3 are symmetrically arranged under the aerial recovery mother aircraft as a group. At the same time, this embodiment is not limited to only having one first hanging drone 2 and second hanging drone 3. Multiple hanging drones can also be arranged, as long as the ropes can be formed into a net shape to capture fixed-wing drones.

[0076] In this embodiment, if Figure 2 and Figure 3 As shown, the first hanging drone 2 and the second hanging drone 3 also include a magnetic buckle 11; the first hanging drone 2 also includes a groove 9, which is located below the guide hole 6; the second hanging drone 3 also includes a boss 10, which is located below the guide hole 6; when the first hanging drone 2 and the second hanging drone 3 slide closer along the rope 101, they can automatically align with the center to complete the splicing, and the magnetic buckle 11 is used to achieve suction and fixation when the capture in the air is completed.

[0077] Optimally, the front of the support plate 7 is slightly tilted, and the tilting angle of the rear of the support plate 7 is greater than the tilting angle of the front of the support plate, so that the wings of the fixed-wing UAV can be stuck after the air capture is completed to prevent it from sliding back and forth.

[0078] At the same time, considering the need to minimize the number of actuators while maintaining six-degree-of-freedom controllability, a dual-rotor solution is the optimal solution. The dual-rotor drone's fuselage cross-section features a symmetrical airfoil, which provides it with yaw-stability. In addition to the aforementioned devices, the first and second pylon drones 2 and 3 also have the same structure as existing drones. For example, the drone fuselage 5 houses components such as a battery, flight control board, and electronic speed controllers. The drone fuselage 5 is equipped with a tilt mechanism 13, a brushless motor 12, and propellers at the front and rear, respectively. The tilt mechanism 13 can drive the brushless motor 12 or propeller to swing left and right, with the propeller generating a pulling force pointing downward relative to the brushless motor 12.

[0079] The first hanging UAV 2 and the second hanging UAV 3 are mainly affected by the air disturbance force, propeller tension and rope tension during the flight. If the maximum tension generated by the propeller is T pmax , then when the static equilibrium state is reached, the maximum angle of the rope loop is:

[0080]

[0081] Where m is the mass of the first or second hanging drone, g is the acceleration of gravity, T pmax The maximum thrust generated by the propeller.

[0082] In this embodiment, if Figure 5 As shown, the winding device 102 includes a winding motor 1021, a core shaft 1022, a rolling bearing 1023 and an electrical connection plug 1024. The two ends of the core shaft 1022 are supported by the rolling bearings 1023 and the two ends of the rolling bearings 1023 are fixed to the mother machine body. The middle part of the core shaft 1022 is driven by the winding motor 1021, and the winding motor 1021 is fixed to the mother machine body through the base. The core shaft 1022 is driven to rotate by the winding motor 1021, which can realize the retraction and release of ropes and cables; the aerial recovery mother machine 1 also includes a power supply data interface Port 103; the rope and the cable are no longer twisted into one strand when approaching the first hanging drone and the second hanging drone, wherein the rope 101 suspends the first hanging drone 2 and the second hanging drone 3 to the bottom of the aerial recovery mother machine 1 through the guide hole, and the cable 104 does not pass through the guide hole, but is directly connected to the data interface of the first hanging drone and the second hanging drone. The rope 101 and the cable are twisted into one strand in the winding device, and the two ends of the rope 101 and the cable are fixed to the core shaft, and are connected to the power supply data interface 103 through the electrical connection plug 1024.

[0083] This embodiment provides a multi-machine coordinated UAV aerial recovery and release method, including: aerial recovery and aerial release processes;

[0084] like Figure 6 As shown, the aerial recovery process includes:

[0085] S101: When the aerial recovery mother machine detects the fixed-wing UAV, it controls the winding device to release the entire length of the rope and cable. After receiving the control command, the first hanging UAV and the second hanging UAV open the rope through the guide hole. The aerial recovery mother machine, the first hanging UAV and the second hanging UAV coordinate to control the center of the rope loop to align with the nose of the fixed-wing UAV, and wait for the fixed-wing UAV to enter the rope loop. The rope loop is a loop composed of the ropes pulled by the aerial recovery mother machine, the first hanging UAV and the second hanging UAV. Figure 9 As shown;

[0086] S102: The aerial recovery mother aircraft detects that the nose of the fixed-wing UAV has entered the rope loop. The aerial recovery mother aircraft sends a control command to the first and second hanging UAVs via the cable. After receiving the control command, the first and second hanging UAVs move closer to each other while maintaining a horizontal attitude. The aerial recovery mother aircraft reclaims the rope and cable.

[0087] S103: The fixed-wing UAV descends in altitude under the control of the coordinated command until the wings on both sides of the fixed-wing UAV touch the support plate, completing the air capture. The fixed-wing UAV shuts down its own power system and stops working. Figure 10 As shown;

[0088] S104: The aerial recovery mother machine continues to recover the ropes and cables. The first hanging drone and the second hanging drone use their own power to maintain a horizontal posture to support the fixed-wing drone, and then retract the fixed-wing drone to the bottom of the aerial recovery mother machine. The locking device and the electromagnet are attracted, and the recovery is completed. Figure 11 As shown;

[0089] like Figure 7 As shown, the aerial release process includes:

[0090] S201: The aerial recovery mother aircraft and the fixed-wing UAV take off vertically as a whole and accelerate forward. When the release speed is reached, the aerial recovery mother aircraft sends a power-off command to the first and second hanging UAVs via a cable. After receiving the power-off command, the electromagnets on the first and second hanging UAVs are powered off, causing the electromagnets to disengage from the locking devices.

[0091] S202: The aerial recovery mother aircraft controls the winding device to release the rope and cable. The first and second hanging drones remain horizontal and support the fixed-wing drone, and are lowered to the lowest point along the ropes together with the fixed-wing drone.

[0092] S203: After the aerial recovery mother aircraft controls the winding device to release all the ropes, the first hanging UAV and the second hanging UAV receive the control command and roll around the x-axis and y-axis of their own body axis respectively, generating a tendency to move to the left and right, and open the rope loop. At the same time, due to the gradual increase in the pitch angle, the support plate and the wings of the fixed-wing UAV gradually separate. The roll angle is as follows: Figure 12 As shown;

[0093] S204: The forward component force generated by the change in the pitch angle of the first hanging UAV and the second hanging UAV pulls the rope loop forward, and at the same time, the aerial recovery mother aircraft accelerates forward, and the fixed-wing UAV slides out of the rope loop backward, completing the aerial release.

[0094] In this embodiment, the aerial recovery process S103 further includes:

[0095] The fixed-wing drone descends under the control of the coordinated command until the wings on both sides of the fixed-wing drone touch the support plate. Then, the grooves and bosses cooperate and the first hanging drone and the second hanging drone are attracted together through the magnetic buckle, completing the aerial capture. The fixed-wing drone, the first hanging drone and the second hanging drone are combined into one, performing vertical take-off and landing.

[0096] The aerial release process also includes:

[0097] S205: The fixed-wing UAV's own power system is activated to generate thrust to continue horizontal flight, and the mother aircraft is recovered in the air to retract the ropes and cables.

[0098] In this embodiment, in order to minimize the number of actuators while maintaining 6-DOF controllability, the first and second hanging drones are designed as dual-rotor drones. The six-DOF control method of the hanging dual-rotor drones is as follows:

[0099] 1) Rolling around the x-axis of the fuselage axis: The front and rear tilting mechanisms tilt to the same side, which can deflect the propeller pulling direction and generate a rolling moment.

[0100] 2) Pitching around the Y-axis of the fuselage axis: The front propeller reduces the thrust and the rear propeller increases the thrust, which can generate a positive pitching moment, and vice versa.

[0101] 3) Yaw around the z-axis of the fuselage axis system: The front and rear tilting mechanisms are differentially tilted, so that the pulling forces of the front and rear propellers are biased in opposite directions, which can generate a yaw moment.

[0102] 4) Displacement in the x-axis direction: By changing the pitch angle of the body, a pulling force in the x-axis direction is generated, thereby controlling the acceleration, velocity and displacement in the x-axis direction.

[0103] 5) Displacement in the y-axis direction: By changing the roll angle of the body, a pulling force in the y-axis direction is generated, thereby controlling the acceleration, velocity and displacement in the y-axis direction.

[0104] 6) Displacement in the z-axis direction: The displacement in the z-axis direction is directly controlled by retracting and releasing the length of the cable through the winding device.

[0105] During the aerial recovery process, the first and second hanging drones use differential GPS to obtain their precise positions relative to the aerial recovery mother aircraft, with the error controlled to the order of millimeters. The aerial recovery mother aircraft obtains the position of the fixed-wing drone by communicating with the fixed-wing drone to be recovered or by visual recognition, radar detection, etc., and then calculates the desired relative position [x r y r z r ] is sent as a control instruction to the first hanging drone and the second hanging drone via the data line, and the desired cable length l is sent as a length instruction to the winding device. The first hanging drone and the second hanging drone calculate the desired balance roll angle φ under the drive of the desired position instruction trim , open the rope loop to a specific angle, and further coordinate with the aerial recovery mother aircraft to control the position and orientation of the rope loop in the air, and dynamically align it with the expected flight path of the fixed-wing UAV to be recovered in real time.

[0106] like Figure 8 As shown in the figure, the realization process of the control algorithm mainly includes: the aerial recovery mother aircraft will move the desired relative position [x r y r z r ] is sent as a control instruction to the first hanging UAV and the second hanging UAV through the cable. The first hanging UAV and the second hanging UAV generate electrical control instructions for the motor and the servo through the position control loop and the attitude control loop according to the control instruction of the aerial recovery mother aircraft. Specifically:

[0107] Position control loop includes: Position deviation through P xzy The module generates the desired speed V d , expected speed V d By PID V The module generates the expected acceleration A d , the expected acceleration A d (a xd ,a yd ,a zd ) into the dynamic model to solve for the desired roll angle φ d and the desired pitch angle θ d ;

[0108] The attitude control loop consists of: d , desired pitch angle θd and the model predicts the feedforward settlement equilibrium roll angle φ trim The superposition is used as the desired attitude angle, and the desired attitude angle is obtained by P Θ The module obtains the desired attitude angular rate ω d , attitude angular rate ω d By PID ω The module obtains the desired torque τ d In this embodiment, if the first hanging UAV and the second hanging UAV are dual-rotor UAVs, specific electrical control instructions are generated for the four actuators of the front and rear tilt mechanism and the front and rear motors according to the control allocation matrix.

[0109] Desired roll angle φ d and the desired pitch angle θ d The calculation formula is:

[0110] φ d =k φ a yd

[0111] θ d =k θ a xd

[0112] Among them, k φ Indicates the roll scale coefficient, k θ Indicates the pitch scale coefficient, a yd represents the desired acceleration in the y direction, a xd represents the desired acceleration in the x direction;

[0113] Balanced roll angle φ trim The calculation formula is:

[0114]

[0115]

[0116] Where m is the mass of the first or second hanging drone, g is the acceleration of gravity, T prop represents the propeller tension, and γ represents the rope expansion angle, such as Figure 13 As shown, y r1 Indicates the expected relative position of the first suspended UAV in the y direction, y r2 Indicates the expected relative position of the second suspended UAV in the y direction.

[0117] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Reference can be made to the common and similar parts between the various embodiments. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and the relevant parts can be referred to the method description.

[0118] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A multi-machine coordinated UAV aerial recovery and release system, characterized by: It includes an aerial recovery mother machine, a first hanging UAV, a second hanging UAV and a fixed-wing UAV, wherein the first hanging UAV and the second hanging UAV are symmetrically arranged below the aerial recovery mother machine; The aerial recovery mother machine includes a mother machine fuselage, a winding device and a locking device arranged below the mother machine fuselage, the winding device is used to retract and release ropes and cables, the aerial recovery mother machine supplies power and sends instructions to the first hanging drone and the second hanging drone through the cable, and retracts and releases the first hanging drone and the second hanging drone through the rope; The first hanging drone and the second hanging drone both include a drone body, a guide hole is provided at the center of gravity of the drone body, the guide hole is used for the rope to pass through, a support plate is provided on the top of the drone body, the support plate is used to clamp the wing of the fixed-wing drone when the aerial capture is completed, and an electromagnet is provided at the rear of the support plate, which is used to engage with the locking device to fix it when the recovery is completed; The first hanging drone and the second hanging drone also include a magnetic buckle; The first hanging drone also includes a groove, the groove being located below the guide hole; The second hanging drone also includes a boss, which is located below the guide hole; The grooves and bosses are adapted to each other, and the magnetic buckle is used to achieve suction and fixation when the capture in the air is completed.

2. The multi-machine coordinated UAV aerial recovery and release system according to claim 1 is characterized in that: Ropes and cables are twisted into one strand in the reel.

3. The multi-machine coordinated UAV aerial recovery and release system according to claim 2 is characterized in that: The winding device includes a winding motor, a core shaft, a rolling bearing and an electrical connection plug. The two ends of the core shaft are supported by rolling bearings, and the two ends of the rolling bearings are fixed to the mother machine body. The middle part of the core shaft is driven by the winding motor, and the winding motor is fixed to the mother machine body through a base. The aerial recovery mother aircraft also includes a power supply and data interface; The rope suspends the first hanging UAV and the second hanging UAV to the bottom of the aerial recovery mother machine through the guide hole, and both ends of the rope and cable are connected to the power supply data interface through electrical connection plugs.

4. The multi-machine coordinated UAV aerial recovery and release system according to claim 1 is characterized in that: The tilting angle of the rear portion of the support plate is greater than the tilting angle of the front portion of the support plate.

5. A multi-machine coordinated UAV aerial recovery and release method, the method is implemented based on the multi-machine coordinated UAV aerial recovery and release system described in any one of claims 1-4, characterized in that: Includes: aerial recovery and aerial release processes; The aerial recovery process includes: S101: When the aerial recovery mother aircraft detects the fixed-wing UAV, it controls the winding device to release the entire length of the rope and cable. After receiving the control command, the first and second hanging UAVs extend the ropes through the guide holes. The aerial recovery mother aircraft, the first and second hanging UAVs coordinately control the center of the rope loop to align with the nose of the fixed-wing UAV, and wait for the fixed-wing UAV to enter the rope loop. S102: The aerial recovery mother aircraft detects that the nose of the fixed-wing UAV has entered the rope loop. The aerial recovery mother aircraft sends a control command to the first and second hanging UAVs via the cable. After receiving the control command, the first and second hanging UAVs move closer to each other while maintaining a horizontal attitude. The aerial recovery mother aircraft reclaims the rope and cable. S103: The fixed-wing UAV descends under the control of the coordinated command until both wings of the fixed-wing UAV touch the support plate, completing the aerial capture and the fixed-wing UAV stops operating; S104: The aerial recovery mother aircraft continues to recover the ropes and cables. The first and second hanging drones maintain a horizontal posture using their own power to support the fixed-wing drone. The fixed-wing drone is retracted to the bottom of the aerial recovery mother aircraft. The locking device engages the electromagnet, and the recovery is complete. The aerial release process includes: S201: The aerial recovery mother aircraft and the fixed-wing UAV accelerate forward as a whole. When the release speed is reached, the aerial recovery mother aircraft sends a power-off command to the first and second hanging UAVs via a cable. After receiving the power-off command, the electromagnets on the first and second hanging UAVs are powered off, causing the electromagnets to disengage from the locking devices. S202: The aerial recovery mother aircraft controls the winding device to release the rope and cable. The first and second hanging drones remain horizontal and support the fixed-wing drone, and are lowered to the lowest point along the ropes together with the fixed-wing drone. S203: After the aerial recovery mother aircraft controls the winding device to release all the ropes, the first and second hanging drones receive control commands and roll and pitch around their own body axes, respectively, to the left and right, thereby opening the rope loops. Simultaneously, as the pitch angle gradually increases, the pallet gradually separates from the fixed-wing drone's wings. S204: The forward component force generated by the change in the pitch angle of the first hanging UAV and the second hanging UAV pulls the rope loop forward, and at the same time, the aerial recovery mother aircraft accelerates forward, and the fixed-wing UAV slides out of the rope loop backward, completing the aerial release.

6. The method for recovering and releasing UAVs in mid-air by multiple drones according to claim 5, characterized in that: The aerial recovery process S103 also includes: The fixed-wing drone descends under the control of the coordinated command until the wings on both sides of the fixed-wing drone touch the support plate. Then, the grooves and bosses cooperate and the first hanging drone and the second hanging drone are attracted together through the magnetic buckle, completing the aerial capture. The aerial release process also includes: S205: The fixed-wing UAV's own power system is activated to generate thrust to continue horizontal flight, and the mother aircraft is recovered in the air to retract the ropes and cables.

7. The method for recovering and releasing UAVs in mid-air by multiple drones according to claim 5, characterized in that: The control instruction is: the aerial recovery mother aircraft will move the desired relative position [x r y r z r ] is sent as a control instruction to the first hanging UAV and the second hanging UAV through the cable. The first hanging UAV and the second hanging UAV generate electrical control instructions for the motor and the servo through the position control loop and the attitude control loop according to the control instruction of the aerial recovery mother aircraft. Specifically: Position control loop includes: Position deviation through P xzy The module generates the desired speed V d , expected speed V d By PID V The module generates the expected acceleration A d (a xd ,a yd ,a zd ), the expected acceleration A d (a xd ,a yd ,a zd ) into the dynamic model to solve for the desired roll angle φ d and the desired pitch angle θ d ; The attitude control loop consists of: d , desired pitch angle θ d and the model predicts the feedforward settlement equilibrium roll angle φ trim The superposition is used as the desired attitude angle, and the desired attitude angle is obtained by P Θ The module obtains the desired attitude angular rate ω d , attitude angular rate ω d By PID ω The module obtains the desired torque τ d .

8. The method for recovering and releasing UAVs in mid-air by multiple drones according to claim 7, characterized in that: Desired roll angle φ d and the desired pitch angle θ d The calculation formula is: Among them, k φ Indicates the roll scale coefficient, k θ Indicates the pitch scale coefficient, a yd represents the desired acceleration in the y direction, a xd represents the desired acceleration in the x direction; Balanced roll angle φ trim The calculation formula is: Where m is the mass of the first or second hanging drone, g is the acceleration of gravity, T prop represents the propeller thrust, γ represents the rope loop expansion angle, y r1 Indicates the expected relative position of the first suspended UAV in the y direction, y r2 represents the desired relative position of the second suspended UAV in the y direction, and l is the length of the rope.

9. The method for recovering and releasing UAVs in mid-air by multiple drones according to claim 5, characterized in that: Maximum opening angle of the rope loop γ max for: Where m is the mass of the first or second hanging drone, g is the acceleration of gravity, T pmax The maximum thrust generated by the propeller.

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