A fixed-wing unmanned aerial vehicle air-based launching and recovering device and method based on a rotor unmanned aerial vehicle platform

Abstract

This invention discloses an airborne launch and recovery device and method for fixed-wing UAVs based on a rotary-wing UAV platform. A rotatable frame with a hook mounted on the fuselage of the fixed-wing UAV is connected to a carbon rod suspended by ropes on a rotary-wing UAV array via an electromagnet, allowing the fixed-wing aircraft to maintain a nose-down orientation. By disconnecting the excitation current of the electromagnet, a dive launch of the fixed-wing aircraft can be achieved. In an aerial recovery scenario, the hook on the fixed-wing UAV can be blocked by the carbon rod, allowing it to be attached to the rod and achieve synchronized flight between the fixed-wing and rotary-wing platforms. After the fixed-wing UAV's power is shut off, it is suspended to the ground by the rotary-wing UAV array for recovery. This invention can simultaneously meet multiple scenarios such as hoisting, launch, and recovery. Furthermore, it can be applied by adjusting the dimensional parameters of the mechanism according to the different types of fixed-wing aircraft to be deployed, and can be combined with algorithms to maintain stability during launch / dockback. Therefore, it possesses good economic efficiency, versatility, and scalability.

Description

Technical Field

[0002] This invention belongs to the field of unmanned aerial vehicle (UAV) technology, specifically relating to an airborne launch and recovery device and method for a fixed-wing UAV based on a rotary-wing UAV platform. Background Technology

[0003] Fixed-wing UAVs have high requirements for takeoff and landing sites, relying on runways or catapults for launch and recovery, directly impacting their flexibility, adaptability, and economy. The availability of a sufficiently safe and rapid launch solution, and the reliability and precision of the recovery phase, are crucial indicators of the UAV system's availability and economic efficiency. The long endurance, high payload capacity, and high flight speed of fixed-wing UAVs have led to their wide application in military, surveying, geology, petroleum, and agriculture / forestry industries. However, the difficulty of launch and recovery is also a significant factor limiting their deployment. Taking naval platforms as an example, without considering sea conditions, the space typically available for UAV use is only about 20 m × 10 m, making existing takeoff and landing methods insufficient for the mission requirements of fixed-wing UAVs. To address this shortcoming, airborne launch and recovery systems for fixed-wing UAVs have emerged.

[0004] Regarding air-launch and recovery systems, the US MX-1016 Tip-Tow and Reconnaissance Parasite Aircraft projects explored various approaches to air-launch and recovery of fixed-wing aircraft. The MX-1016 Tip-Tow project used a wingtip cone-and-screw connection to achieve in-flight docking and release between a B-29 bomber and an F-84 fighter, while the Parasite Aircraft project used a fuselage truss connection to achieve in-flight docking, recovery, and release between a B-36 bomber and an F-84 fighter. However, during a test of the MX-1016 Tip-Tow project, due to aerodynamic interference between the mother and daughter aircraft, the F-86 fighter on the left underwent a right roll and violently collided with the wing of the B-29, resulting in the deaths of one crew member on the F-84 and all five crew members on the B-29. The US DRAPA program is developing the X-61 "Gremlin" UAV to perform more efficient and lower-cost distributed air combat missions. It employs an actively controlled GAV connected to a stable towed docking device. It is evident that the aforementioned launch and recovery devices all have shortcomings and lack high versatility, being designed only for specific airborne platforms, resulting in poor economic efficiency and applicability. Therefore, research is needed on novel fixed-wing UAV airborne launch and recovery devices to explore new technologies and provide technical support for future airborne launch and recovery. Summary of the Invention

[0005] To address the aforementioned problems, this invention proposes an airborne launch and recovery device and method for fixed-wing UAVs based on a rotary-wing UAV platform. The device comprises a hook-and-rod frame and servo drive mechanism mounted on the fixed-wing UAV, which engages with a folding linkage suspended from the rotary-wing UAV. The two components are electromagnetically locked together. The device is carried by a dual-rotor UAV in conjunction with the fixed-wing UAV, enabling stable, fixed-point launches in the air. Simultaneously, the dual-rotor UAV and the fixed-wing UAV can perform precise hook-and-rod docking in mid-air, eliminating external interference during docking. This invention overcomes site limitations, avoids the safety hazards of traditional airborne docking, features a simple structure, strong adaptability, and is convenient and economical to use. It effectively improves the deployment flexibility and environmental adaptability of fixed-wing UAVs, meeting the needs of rapid take-off and landing operations in multiple fields.

[0006] The present invention relates to a fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform, comprising a rod-hook assembly frame and a drive mechanism mounted on the side of the fixed-wing UAV, and a launch and recovery mechanism on the side of the rotary-wing UAV.

[0007] The main body of the rod-hook assembly frame is a frame structure with connecting rods, and two hooks are installed at the ends. The openings of the two hooks face forward, and electromagnets for the fixed-wing UAV are fixedly installed on the outside of the two hooks. At the same time, diffuse reflection fiber optic sensors are installed at the openings of the two hooks to confirm whether the connecting rods in the launch and recovery mechanism have entered the hooks during the recovery phase.

[0008] The drive mechanism includes a servo motor and a rotating shaft; the servo motor is fixedly mounted on the top of the fuselage, located in front of the wing near the wing; the servo motor output shaft is arranged laterally along the fuselage and coaxially fixed to one end of the rotating shaft. The other end of the rotating shaft is connected to a support mounted on the top of the fuselage via a bearing to form a rotating pair. The front end of the aforementioned lever-hook assembly frame is designed with a connecting ring that is sleeved and fixed to the rotating shaft, and the rotation of the lever-hook assembly frame around the rotating shaft is driven by the servo motor.

[0009] The launch and recovery mechanism includes three connecting rods and ropes. The three connecting rods are foldable rod structures consisting of three rods hinged at their ends to form a rotating joint. Both ends of the three connecting rods are connected and fixed to the bottom ends of two ropes, the top ends of which are fixed to the arms of two rotorcraft UAVs. The middle connecting rod is used to suspend the fixed-wing UAV by engaging with the two hook openings in the aforementioned rod-hook assembly frame. Simultaneously, two rotorcraft-side electromagnets are installed on the middle connecting rod to engage with the rotorcraft-side electromagnets to attract and secure the fixed-wing UAV.

[0010] The specific steps for air-based launch of a fixed-wing UAV are as follows:

[0011] Step 1: Place both the fixed-wing and rotary-wing drones on the ground; then energize the electromagnet on the fixed-wing drone side and connect it with the electromagnet on the rotary-wing drone side on the three-section connecting rod to complete the hoisting of the fixed-wing drone; after successful connection, the contact switch will provide a locking signal.

[0012] Step 2: Adjust the lever-hook assembly frame to the preset angle using the servo motor to ensure that the suspension position is located behind the center of gravity of the fixed-wing UAV.

[0013] Step 3: The two rotary-wing drones perform a pre-takeoff self-check. After the self-check is completed and found to be normal, they enter the takeoff-ready state.

[0014] Step 4: The two rotary-wing drones take off vertically at the preset climb rate, carrying the fixed-wing drone into the air smoothly.

[0015] Step 5: After the two rotary-wing drones carrying the fixed-wing drone arrive at the preset launch point, the two rotary-wing drones adjust their attitude to hover. At this time, the electromagnets on the side of the rotary-wing drone and the side of the fixed-wing drone are simultaneously de-energized, and the fixed-wing drone separates from the intermediate connecting rod under the action of gravity and begins to fall freely.

[0016] Step 6: After the fixed-wing UAV separates, it enters a powerless dive state until the airspeed reaches the safe takeoff speed. Then, it automatically executes the pull-up procedure, smoothly transitioning the aircraft from a dive attitude to a level flight attitude and accelerating to cruise speed, thus completing the launch of the fixed-wing UAV.

[0017] The specific steps for recovering a fixed-wing drone are as follows:

[0018] Step 1) When the fixed-wing UAV needs to return after completing its mission, control the fixed-wing UAV and the two quadcopter UAVs to fly to the preset recovery area simultaneously.

[0019] Step 2) After reaching the recovery area, control the two quadcopter drones to the preset recovery positions within the recovery area and adjust the two quadcopter drones to the same height. At the same time, control the fixed-wing drone to fly to the preset capture area below the middle link, and drive the stick hook assembly frame to rotate around the pivot to the preset angle via the servo motor, while keeping the horizontal position of the stick hook assembly frame on the fixed-wing drone directly facing the middle link.

[0020] Step 3) When the fixed-wing UAV reaches the capture area, the lever-hook assembly frame collides with the mid-section connecting rod. The connecting rod then slides along the lever-hook assembly frame towards the hook and into the hook opening. The diffuse reflection fiber optic sensor at the opening receives an obstruction signal, confirming that the mid-section connecting rod has entered the hook, and the fixed-wing UAV enters a suspended state. Subsequently, the forward kinetic energy of the fixed-wing UAV is transferred to the two quadcopter UAVs through the mid-section connecting rod. Under the impact, the mid-section connecting rod forms a buffer structure at a certain angle with the side connecting rods.

[0021] Step 4) The two rotary-wing UAVs eliminate attitude disturbances at the moment of capture through attitude adjustment and tension compensation, and share the weight of the fixed-wing UAV.

[0022] Step 5) Two quadcopter drones carrying the captured fixed-wing drone slowly fly to the designated safe recovery area. During the process, the fixed-wing drone loses its own power and relies entirely on the two quadcopter drones for hoisting and flight.

[0023] Step 6) The two rotary-wing drones descend in coordination to place the suspended fixed-wing drone smoothly on the ground, completing the recovery of the fixed-wing drone.

[0024] The advantages of this invention are:

[0025] 1. The present invention is a fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform. It adopts a modular design and can set up a rod and hook combination structure and recovery frame of corresponding size according to the type of the UAV carried. It is convenient for rapid iteration and has good versatility and expandability.

[0026] 2. The present invention is a fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform. It adopts a double-rod and double-hook design, which greatly increases the stability during the hoisting and recovery stages compared with a single hook.

[0027] 3. The present invention is a fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform. It only requires one set of mechanisms to meet the three modes of hoisting, launching and recovery. The device has a simple structure and high efficiency. Under the action of dynamic differential positioning technology and anti-sway control law, it can maintain the accuracy during launch / docking and the stability during hoisting. The method has been verified in flight tests.

[0028] 4. The fixed-wing UAV airborne launch and recovery device based on the rotary-wing UAV platform of the present invention has a docking margin of decimeter level, which is sufficient to cover the errors caused by software aspects such as airborne differential positioning, data transmission, and calculation. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the side rod hook assembly frame and drive mechanism of the fixed-wing UAV in this invention;

[0030] Figure 2 This is a schematic diagram of the side launch and recovery mechanism of the rotary-wing UAV in this invention;

[0031] Figure 3 This is a schematic diagram of the rod and hook combined frame structure;

[0032] Figure 4 A schematic diagram showing the suspension attitude between a fixed-wing UAV and a rotary-wing UAV before launch.

[0033] Figure 5 This is a schematic diagram showing the relative positions and attitudes of the fixed-wing aircraft and the rotary-wing UAV platform as they approach the recovery phase.

[0034] Figure 6 A schematic diagram showing the attitude of the fixed-wing aircraft and rotary-wing UAV platforms combined via the recovery device after recovery is complete and their attitude is stable.

[0035] In the picture:

[0036] 1-Hook and rod assembly frame;

[0037] 101-Carbon rod; 102-Hook; 103-Side electromagnet for fixed-wing UAV; 104-Connecting ring;

[0038] 2-Drive mechanism;

[0039] 201-Servo motor; 202-Shaft; 203-Torque limiter;

[0040] 3- Launch and recovery mechanism;

[0041] 301 - Three-section carbon rod; 302 - Limiting rod; 303 - Rope; 304 - Electromagnet on the side of a rotary-wing UAV. Detailed Implementation

[0042] The present invention will now be described in further detail with reference to the accompanying drawings.

[0043] This invention relates to an airborne launch and recovery device for a fixed-wing unmanned aerial vehicle (UAV) based on a rotary-wing UAV platform. It includes a rod-hook assembly frame 1 and a drive mechanism 2 mounted on the side of the fixed-wing UAV, and a launch and recovery mechanism 3 on the side of the rotary-wing UAV. Figure 1 , Figure 2 As shown.

[0044] The rod and hook assembly frame 1 includes a frame body composed of five coplanarly arranged carbon rods 101, two hooks 102, two electromagnets 103, and two fiber optic sensors; let the five carbon rods 101 be carbon rods A to F, and the two hooks 102 be hook A and hook B. Figure 3 As shown, carbon rods A, B, and C are short carbon rods of equal length, with a length not exceeding the lateral width of the fuselage. Carbon rods D and E are long carbon rods, with a length approximately equal to the distance between the leading edge of the wing and the tip of the fuselage.

[0045] Carbon rods A and B are fixedly connected at their front ends, and their ends are fixedly connected to both ends of carbon rod C, respectively. Carbon rods A, B, and C form an equilateral triangle. Carbon rods D and E are perpendicular to carbon rod C, with their front ends fixedly connected to both ends of carbon rod C, and their ends fixedly connected to carbon rod F, respectively. Simultaneously, the ends of carbon rods D and E are connected to hooks A and B, respectively. The front ends of carbon rods A and B can be fixedly connected via a two-phase connector; the ends of carbon rods A, C, and D, as well as the ends of carbon rods B, C, and E, can all be fixedly connected via three-phase connectors; similarly, the ends of carbon rods D and F connected to hook A, and the ends of carbon rods E and F connected to hook B, can also be fixed via three-phase connectors.

[0046] Both hooks A and B are U-shaped structures with their openings facing forward. One end is a connecting section that is fixedly connected to the ends of carbon rods D and E. A fixed-wing UAV-side electromagnet 103 is fixedly installed on the outer side of the bent portion of hooks A and B, for use with the rotor-wing UAV-side electromagnet 301. Simultaneously, diffuse reflection fiber optic sensors are installed at the openings of hooks A and B to confirm whether the recovery support has entered hook 102 during the recovery phase.

[0047] In the aforementioned rod and hook assembly frame 1, an integrally formed connecting ring 104 is also designed at the junction of carbon rod A and carbon rod B for connecting the drive mechanism 2.

[0048] The drive mechanism 2 includes a servo motor 201, a rotating shaft 202, and a torque limiter 203. The servo motor 201 is fixedly mounted on the top of the fuselage, located in front of the wing near the wing position; the output shaft of the servo motor 201 is arranged laterally along the fuselage. The output shaft of the servo motor 201 is coaxially fixed to one end of the rotating shaft 202, and the other end of the rotating shaft 202 is connected to a support mounted on the top of the fuselage via a bearing to form a rotating pair. The connecting ring 104 at the front end of the aforementioned lever-hook assembly frame 1 and the torque limiter 203 are both sleeved on the rotating shaft, and the two are connected and fixed by friction. Then, the power is output through the servo motor 201 and transmitted to the torque limiter 203 via the output shaft of the servo motor 201. The torque limiter 203 transmits the torque to the connecting ring 104, which in turn drives the entire rotating shaft 202 of the rod hook assembly frame 1 to rotate in the plane of symmetry of the fuselage. During the process, when the torque exceeds the preset threshold, the plates inside the torque limiter 203 slip, cutting off the power transmission and protecting the rod hook assembly frame 1 from being broken.

[0049] The launch and recovery mechanism 3 includes three carbon rods 301, a limiting rod 302, and ropes 303. Each carbon rod 301 consists of three coaxial carbon rods, with their ends hinged together to form a rotating pair, allowing the carbon rods on both sides to rotate relative to each other. Both ends of the three carbon rods 301 are connected and fixed to the bottom ends of two ropes 303, the top ends of which are wound around and fixed to the arms of two rotorcraft UAVs. Simultaneously, the two ropes 303 are connected and fixed to both ends of the limiting rod 302 at their middle positions, limiting the horizontal distance between the two rotorcraft UAVs and preventing them from colliding when the launch and recovery mechanism 3 is subjected to impact or disturbance. Two rotorcraft-side electromagnets 304 are installed in the middle of the middle carbon rod of the three carbon rods 301, with the distance between the two rotorcraft-side electromagnets 304 equal to the distance between the two fixed-wing UAV-side electromagnets 103 on the two hooks 102. The two rotary-wing UAVs equipped with the launch and recovery mechanism 3 were not docked, and the three carbon rods in the launch and recovery mechanism 3 were coaxial.

[0050] Based on the above-described fixed-wing UAV airborne launch and recovery device, the specific method for fixed-wing UAV airborne launch and recovery is as follows:

[0051] The specific steps for launching a fixed-wing UAV are as follows:

[0052] Step 1: Dock between the fixed-wing UAV and the rotary-wing UAV.

[0053] Both the fixed-wing and rotary-wing UAVs are set up on the ground; then the electromagnet 103 on the side of the fixed-wing UAV is energized and attracts and docks with the electromagnet on the side of the rotary-wing UAV on the three-section carbon rod 301. After the connection is successful, the contact switch sends a "locked in place" signal.

[0054] Step 2: Adjust the lever-hook assembly frame 1 to the preset angle using servo motor 201 to ensure that the hanging position (where the electromagnets attract each other) is located behind the center of gravity of the fixed-wing UAV, in preparation for the nose-down torque during subsequent launch.

[0055] Step 3: The collaborative control unit on the rotorcraft drone performs a pre-takeoff self-check on both rotorcraft drones. After the self-check is completed and normal, the drones enter the takeoff-ready state.

[0056] Step 4: Send a synchronized takeoff command to both rotary-wing UAVs, causing them to take off vertically at a preset climb rate, carrying the fixed-wing UAV into the air smoothly. During the process, under the weight of the fixed-wing UAV, the middle carbon rod and the two side carbon rods will form a certain angle, thus shortening the length of the entire three-section carbon rod 301, which can reduce the swaying of the fixed-wing UAV during takeoff, making the overall system more stable; and since the hinge of the hook 102 on the fixed-wing UAV fuselage is located behind the center of gravity of the entire aircraft, the fixed wing naturally generates a nose-down torque in the suspended state, keeping the nose down, which is beneficial for subsequent dive-launch, such as Figure 4 As shown.

[0057] Step 5: After the two rotary-wing UAVs carrying the fixed-wing UAV arrive at the preset launch point, the two rotary-wing UAVs adjust their attitude to a hovering state and adjust their noses so that the fixed-wing UAV's nose faces the wind to reduce attitude disturbance after release. At this time, the electromagnet 304 on the side of the rotary-wing UAV and the electromagnet 103 on the side of the fixed-wing UAV are simultaneously de-energized, removing the attraction; the fixed-wing UAV separates from the central carbon rod under the action of gravity and begins free fall. Since the fixed-wing UAV's attachment point is located behind its center of gravity, it naturally maintains a nose-down attitude after release, preparing for the dive to accelerate.

[0058] Step 6: After the fixed-wing UAV separates, it enters a powerless dive state until the airspeed reaches the safe takeoff speed. It then automatically executes the pull-up procedure, smoothly transitioning the aircraft from a dive attitude to a level flight attitude. At this time, the fixed-wing UAV automatically starts the electric ducted fan, and the throttle is gradually pushed up to cruise power, accelerating the aircraft to cruise speed. This completes the launch of the fixed-wing UAV.

[0059] The specific steps for recovering a fixed-wing drone are as follows:

[0060] Step 1) When the fixed-wing UAV needs to return after completing its mission, it is necessary to control the fixed-wing UAV and two quadcopter UAVs to fly to the preset recovery area at the same time.

[0061] Step 2) After reaching the recovery area, further control the two quadcopter drones to reach the preset recovery position within the recovery area, and adjust the two quadcopter drones to the same height; simultaneously, using dynamic differential positioning technology, control the fixed-wing drone to fly towards the preset capture area below the middle carbon rod, and drive the stick hook assembly frame 1 to rotate around the pivot 202 to a preset angle via servo motor 201, while keeping the horizontal position of the stick hook assembly frame 1 on the fixed-wing drone directly facing the middle carbon rod, such as... Figure 5 As shown; at this time, the two quadcopter drones and the fixed-wing drone are flying in the same direction, with the two quadcopter drones in front and the fixed-wing drone behind. The speed of the fixed-wing drone is slightly faster than that of the two quadcopter drones, which can effectively reduce the impact between the hook 102 and the middle connecting rod during the subsequent recovery.

[0062] Step 3) When the fixed-wing UAV reaches the capture area, the rod-hook assembly frame 1 collides with the middle carbon rod, and then the middle carbon rod slides along the rod-hook assembly frame 1 towards the hook 102. When the middle carbon rod slides into the opening of the hook 102, the diffuse reflection fiber optic sensor at the hook 102 receives an obstruction signal, confirming that the middle carbon rod has entered the hook 102, and the fixed-wing UAV enters a suspended state. Subsequently, the forward kinetic energy of the fixed-wing UAV is transferred to the two quadcopter UAVs through the middle carbon rod; under the impact, the middle carbon rod will form a certain angle with the carbon rods on both sides, forming a buffer structure to absorb some of the impact energy, thereby reducing the swaying caused by the impact immediately after docking, and preventing the rod-hook assembly frame 1 from detaching again after entering the hook 102.

[0063] Step 4) The collaborative control unit confirms that the fiber optic sensor signals are valid, the forces on each platform are normal, and the tension is within a safe range. The two rotary-wing UAVs, through attitude adjustment and tension compensation, eliminate attitude disturbances at the moment of capture and share the weight of the fixed-wing. At this point, the anti-sway control law is applied, and through coordinated micro-movements of the two recovery platforms, the swaying of the fixed-wing relative to the recovery frame is reduced as quickly as possible. Ultimately, the speed of the fixed-wing UAV decreases to a stable, synchronized suspension state with the two quadcopter UAVs, achieving the same speed and stable attitude. Figure 6 As shown.

[0064] Step 5) Two quadcopter drones carrying the captured fixed-wing drone slowly fly to the designated safe recovery area. During the process, the fixed-wing drone loses its own power and relies entirely on the two quadcopter drones for hoisting and flight.

[0065] Step 6) The two rotary-wing drones descend in coordination to place the suspended fixed-wing drone smoothly on the ground, completing the recovery of the fixed-wing drone.

[0066] This invention relates to a fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform. The length of each carbon rod can be adjusted to adapt to the launch and recovery requirements of different UAV sizes.

[0067] The above provides a detailed description of the fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform provided by the present invention, from both the fixed-wing side and the rotor side. It also elaborates on its specific working methods in multiple scenarios such as hoisting, launching, and recovery, thereby demonstrating the feasibility and high versatility of the device of the present invention.

Claims

1. A fixed-wing unmanned aerial vehicle (UAV) airborne launch and recovery device based on a rotary-wing UAV platform, characterized in that: This includes a rod-hook assembly frame and drive mechanism mounted on the side of a fixed-wing UAV, and a launch and recovery mechanism on the side of a rotary-wing UAV. The main body of the rod-hook combination frame is a frame structure with connecting rods, and two hooks are installed at the ends. The openings of the two hooks face forward, and electromagnets for fixed-wing UAVs are fixedly installed on the outside of the two hooks. At the same time, diffuse reflection fiber optic sensors are installed at the openings of the two hooks to confirm whether the connecting rods in the launch and recovery mechanism have entered the hooks during the recovery phase. The drive mechanism includes a servo motor and a rotating shaft; the servo motor is fixedly installed on the top of the fuselage, located in front of the wing near the wing; the servo motor output shaft is arranged laterally along the fuselage and is coaxially fixed to one end of the rotating shaft; the other end of the rotating shaft is connected to the support seat installed on the top of the fuselage through a bearing to form a rotating pair; the front end of the aforementioned rod-hook assembly frame is designed with a connecting ring that is sleeved and fixed on the rotating shaft, and the servo motor drives the rod-hook assembly frame to rotate around the rotating shaft; The launch and recovery mechanism includes three connecting rods and ropes; the three connecting rods are foldable rod structures consisting of three rods with their ends hinged together to form a rotating pair; both ends of the three connecting rods are respectively connected and fixed to the bottom ends of two ropes, and the top ends of the two ropes are respectively fixed to the arms of two rotary-wing UAVs; the middle connecting rod is used to cooperate with the two hook openings in the aforementioned rod-hook combination frame to suspend the fixed-wing UAV; at the same time, two rotary-wing UAV-side electromagnets are installed on the middle connecting rod to cooperate with the rotary-wing UAV-side electromagnets to attract and fix the fixed-wing UAV.

2. The fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform as described in claim 1, characterized in that: The main body of the rod-hook assembly frame includes five coplanarly arranged connecting rods, denoted as connecting rods A to F. Connecting rods A, B, and C are short connecting rods of equal length, with a length not exceeding the transverse width of the fuselage. Connecting rods D and E are long connecting rods, with a length approximately equal to the distance between the leading edge of the wing and the end of the fuselage. The front ends of connecting rods A and B are fixedly connected, and their ends are respectively fixedly connected to both ends of connecting rod C. Connecting rods D and E are perpendicular to connecting rod C, with their front ends fixedly connected to both ends of connecting rod C and their ends fixedly connected to connecting rod F. The ends of connecting rods D and E are respectively connected to hooks A and B.

3. The fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform as described in claim 2, characterized in that: The front ends of connecting rod A and connecting rod B can be connected and fixed by a two-phase connector; the ends of connecting rod A, connecting rod C and connecting rod D, as well as the ends of connecting rod B, connecting rod C and connecting rod E, can be connected and fixed by a three-phase connector; the connecting ends of connecting rod D and connecting rod F and hook A, as well as the connecting ends of connecting rod E and connecting rod F and hook B, can be connected and fixed by a three-phase connector.

4. The fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform as described in claim 1, characterized in that: The connecting ring is fixed relative to the rotating shaft by a torque limiter; specifically, the connecting ring and the torque limiter are sleeved on the rotating shaft, and the connecting ring is clamped by the torque limiter. The two are connected and fixed by friction. Then, during the rotation of the rod and hook assembly frame, when the torque exceeds the preset threshold, the plates inside the torque limiter slip, cutting off the power transmission and protecting the rod and hook assembly frame from being broken.

5. The fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform as described in claim 1, characterized in that: The two ropes are fixed to the two ends of a limiting rod at the middle position, and the limiting rod restricts the horizontal distance between the two rotor drones.

6. The airborne launch method of a fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform as described in claim 1, characterized in that: The specific steps are as follows: Step 1: Place both the fixed-wing and rotary-wing drones on the ground; then energize the electromagnet on the fixed-wing drone side and connect it with the electromagnet on the rotary-wing drone side on the three-section connecting rod to complete the hoisting of the fixed-wing drone; after successful connection, the contact switch will provide a locking signal. Step 2: Adjust the lever-hook assembly frame to the preset angle using the servo motor to ensure that the suspension position is located behind the center of gravity of the fixed-wing UAV; Step 3: The two rotary-wing drones perform pre-takeoff self-checks. After the self-checks are completed and normal, they enter the takeoff-ready state. Step 4: The two rotary-wing drones take off vertically at a preset climb rate, carrying the fixed-wing drone into the air smoothly; Step 5: After the two rotary-wing drones carrying the fixed-wing drone arrive at the preset launch point, the two rotary-wing drones adjust their attitude to hover. At this time, the electromagnets on the side of the rotary-wing drone and the side of the fixed-wing drone are simultaneously de-energized, and the fixed-wing drone separates from the middle connecting rod under the action of gravity and begins to fall freely. Step 6: After the fixed-wing UAV separates, it enters a powerless dive state until the airspeed reaches the safe takeoff speed. Then, it automatically executes the pull-up procedure, smoothly transitioning the aircraft from a dive attitude to a level flight attitude and accelerating to cruise speed, thus completing the launch of the fixed-wing UAV.

7. The airborne launch method of a fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform as described in claim 6, characterized in that: During the process, under the weight of the fixed-wing aircraft, the middle section of the three-section linkage forms a certain angle with the two side linkages, which reduces the swaying of the fixed-wing UAV during takeoff; and the fixed-wing UAV naturally generates a nose-down torque when suspended, keeping the nose down.

8. The airborne launch method of a fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform as described in claim 6, characterized in that: In step five, the two rotary-wing drones also adjusted their noses to face the wind, in order to reduce attitude disturbances after release.

9. The recovery method of a fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform as described in claim 1, characterized in that: The specific steps are as follows: Step 1: When the fixed-wing UAV needs to return after completing its mission, control the fixed-wing UAV and the two quadcopter UAVs to fly simultaneously to the preset recovery area; Step 2: After arriving at the recovery area, control the two quadcopter drones to reach the preset recovery position within the recovery area and adjust the two quadcopter drones to the same height; at the same time, control the fixed-wing drone to fly to the preset capture area below the middle link, and drive the stick hook combination frame to rotate around the pivot to the preset angle through the servo motor, while keeping the horizontal position of the stick hook combination frame on the fixed-wing drone facing the middle link. Step 3: When the fixed-wing UAV reaches the capture area, the rod-hook assembly frame collides with the middle connecting rod. The connecting rod then slides along the rod-hook assembly frame towards the hook and into the hook opening. The diffuse reflection fiber optic sensor at the opening receives an obstruction signal, confirming that the middle connecting rod has entered the hook, and the fixed-wing UAV enters a suspended state. Subsequently, the forward kinetic energy of the fixed-wing UAV is transferred to the two quadcopter UAVs through the middle connecting rod. Under the impact, the middle connecting rod forms a certain angle with the connecting rods on both sides, forming a buffer structure. Step 4: The two rotary-wing UAVs eliminate attitude disturbances at the moment of capture through attitude adjustment and tension compensation, and share the weight of the fixed-wing UAV. Step 5: Two quadcopter drones carry the captured fixed-wing drone smoothly to the designated safe recovery area. During the process, the fixed-wing drone loses its own power and relies entirely on the two quadcopter drones for hoisting and flight. Step 6: The two rotary-wing drones descend in coordination to place the suspended fixed-wing drone smoothly on the ground, completing the recovery of the fixed-wing drone.

10. The airborne launch and recovery method of a fixed-wing UAV airborne launch and recovery device based on a rotary-wing UAV platform as described in claim 9, characterized in that: In step 4, by controlling the coordinated micro-movements of the two recovery platforms, the swaying of the fixed wing relative to the recovery frame is reduced, so that the speed of the fixed-wing UAV drops to a stable suspension state with the same speed and attitude as the two quadcopter UAVs.

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