A method for autonomously transferring a load from a first aircraft to a second aircraft in flight, a system comprising the first aircraft and the second aircraft, and an aircraft

Abstract

A method for autonomously transferring a load from a first aircraft (AV) to a second aircraft in flight is provided. Each of the first aircraft and the second aircraft includes a frame having a vertical opening for receiving the load. A plurality of rotors are attached to the frame. The method comprises autonomously performing in flight: a fastening device of the first aircraft holds the load in the vertical opening of the first aircraft so that a bottom end of the load can be accessed by the second aircraft; the second aircraft approaches the first aircraft from below to couple the fastening device of the second aircraft to the bottom end of the load; after the fastening device of the second aircraft is coupled to the bottom end of the load, the fastening device of the first aircraft releases the load; and the fastening device of the second aircraft lowers the load relative to the frame of the second aircraft to move the load into a flight position.

Description

Technical Field

[0001] Examples relate to load exchange between aerial vehicles (AVs). In particular, examples relate to methods for autonomously transferring a load from a first AV to a second AV in flight, systems including the first AV and the second AV, and AVs. Background Art

[0002] Aircraft such as unmanned aerial vehicles (UAVs) play an important role in the transportation of goods and people, offering numerous possibilities for remote sensing. However, the amount of time battery-powered aircraft can remain airborne remains a weakness of the technology. Typically, battery-powered vehicles can extend their range or operating time by using larger batteries. However, battery size is a major cost factor and also affects the weight of the unit, thereby impacting the transportable payload of the vehicle. Charging or replacing batteries while not in flight can significantly increase the aircraft's travel / delivery time.

[0003] Another way to extend the travel / delivery distance is to exchange payloads between multiple aircraft. However, exchanging payloads requires a carefully planned exchange procedure.

[0004] Therefore, there may be a need to safely transfer a load from a first aircraft to a second aircraft. Summary of the Invention

[0005] This need is met by the device and method described in the independent claims. Advantageous embodiments are described in the dependent claims.

[0006] According to a first aspect, the present invention provides a method for autonomously transferring a load from a first aircraft to a second aircraft in flight. Each of the first aircraft and the second aircraft includes a frame having a vertical opening for receiving the load. A plurality of rotors are attached to the frame. The method comprises autonomously performing the following operations in flight: a fastening device of the first aircraft holds the load in the vertical opening of the first aircraft so that a bottom end of the load can be accessed by a second aircraft, the second aircraft approaches the first aircraft from below to couple the fastening device of the second aircraft to the bottom end of the load; after the fastening device of the second aircraft is coupled to the bottom end of the load, the fastening device of the first aircraft releases the load; and the fastening device of the second aircraft lowers the load relative to the frame of the second aircraft to move the load into a flight position.

[0007] According to a second aspect, the present invention provides a system comprising a first aircraft and a second aircraft. Each of the first aircraft and the second aircraft comprises a frame having a vertical opening for receiving a load. A plurality of rotors are attached to the frame. Each of the first aircraft and the second aircraft comprises a control circuit configured to control a corresponding one of the first aircraft and the second aircraft to autonomously perform in flight: a fastening device of the first aircraft holds the load in the vertical opening of the first aircraft so that the bottom end of the load can be contacted by the second aircraft; the second aircraft approaches the first aircraft from below to couple the fastening device of the second aircraft to the bottom end of the load; after the fastening device of the second aircraft is coupled to the bottom end of the load, the fastening device of the first aircraft releases the load; and the fastening device of the second aircraft lowers the load relative to the frame of the second aircraft to move the load to a flight position.

[0008] According to a third aspect, the present invention provides an aircraft. The aircraft includes a frame having a vertical opening for receiving a payload, and a plurality of rotors attached to the frame. Furthermore, the aircraft includes a plurality of rotatable worm gears disposed in the frame. The worm gears are capable of engaging with a plurality of racks of the payload to secure the payload. Furthermore, the aircraft includes at least one controllable actuator for the plurality of rotatable worm gears. The actuator is configured to rotate the plurality of rotatable worm gears to adjust the vertical position of the payload relative to the frame.

[0009] According to a fourth aspect, the present invention provides another aircraft. The aircraft comprises a frame having a vertical opening for receiving a load, and a plurality of rotors attached to the frame. Furthermore, the aircraft comprises a plurality of bolts attached to the sidewalls of the vertical opening. The bolts are capable of engaging corresponding recesses in the surfaces of a plurality of columns of the load to secure the load. The columns of the load can be rotated by the bolts by applying a force along the column axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Some examples of apparatus and / or methods will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0011] Figure 1 A flow chart illustrating an example of a method for autonomously transferring a load from a first aircraft to a second aircraft in flight;

[0012] Figure 2 A top view of an example of an unmanned aerial vehicle is shown;

[0013] Figure 3 Shown Figure 2 A side view of the unmanned aerial vehicle shown in FIG.

[0014] Figure 4An example of a system including a first unmanned aerial vehicle and a second unmanned aerial vehicle is shown;

[0015] Figure 5 A flow chart illustrating yet another example of a method for autonomously transferring a load from a first aircraft to a second aircraft in flight;

[0016] Figure 6a A first example is shown in which the fastening device of an aircraft is implemented using a rotatable worm;

[0017] Figure 6b A first exemplary fastening device comprising a rotatable worm is shown;

[0018] Figure 6c A second exemplary fastening device comprising a rotatable worm is shown;

[0019] Figure 7 shows a side view of a second example, in which the fastening means of the aircraft are realized as bolts;

[0020] Figure 8 Shown Figure 7 A top view of the fastening device shown in FIG; and

[0021] Figure 9 An example of an unfolded cylindrical surface is shown. DETAILED DESCRIPTION

[0022] Various examples will now be described more fully with reference to the accompanying drawings, in which some examples are shown. In the accompanying drawings, the thickness of lines, layers and / or regions may be exaggerated for clarity.

[0023] Therefore, the further examples are capable of various modifications and alternative forms, and some specific examples thereof are shown in the accompanying drawings and described in detail below. However, this detailed description does not limit the further examples to the specific forms described. The further examples encompass all modifications, equivalents, and alternatives within the scope of the present invention. The same or similar numbers refer to the same or similar elements described throughout the drawings, and while providing the same or similar functionality, they can be implemented in the same or modified form when compared to each other.

[0024] It will be understood that when an element is referred to as being "connected" or "coupled" to another element, these elements may be directly connected or coupled through one or more intervening elements. If two elements A and B are combined using "or", without explicit or implicit limitations, it should be understood that all possible combinations are disclosed, i.e., only A, only B, and A and B. Alternative expressions for the same combination are "at least one of A and B" or "A and / or B". The same applies to combinations of more than two elements.

[0025] The terms used to describe specific examples herein are not intended to limit further examples. When singular forms such as "one", "an" and "said" are used and only a single element is neither clearly nor implicitly defined as mandatory, further examples may also use plural elements to implement the same function. Similarly, when a function is subsequently described as being implemented using multiple elements, further examples may use a single element or processing entity to implement the same function. It will be further understood that the terms "comprising", "containing", "including" and / or "comprising" indicate the presence of the features, wholes, steps, operations, processes, actions, elements and / or parts being described when used, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, processes, actions, elements, parts and / or any groups thereof.

[0026] Unless otherwise defined, all terms (including technical and scientific terms) used herein should have the same meaning as commonly used in the art to which examples belong.

[0027] Figure 1 A flow chart of a method 100 for autonomously transferring a payload from a first (e.g., battery-powered) aircraft to a second (e.g., battery-powered) aircraft in flight is shown. In other words, method 100 is used to transfer a payload from a first aircraft to a second aircraft while both aircraft are airborne. The payload transfer from the first aircraft to the second aircraft is performed autonomously, i.e., without external control, such as from an external control center or a human pilot. In some examples, the first aircraft and the second aircraft are drones. In other examples, at least one of the first aircraft and the second aircraft may be manned.

[0028] Each of the first and second aircraft includes a frame (fuselage) having a vertical opening for receiving a payload. In other words, a vertical groove is formed in the frame to accommodate the payload. For each of the first and second aircraft, a plurality of rotors (i.e., two or more rotors) are attached to the frame to propel the aircraft.

[0029] Figure 2, a top view of an exemplary unmanned aerial vehicle 200 that can be used for the first and second aircraft is shown. The unmanned aerial vehicle 200 serves as a carrier for a (payload) 240. The unmanned aerial vehicle 200 includes a generally rectangular frame (fuselage) 210. In other words, the unmanned aerial vehicle 200 includes a frame-shaped fuselage. System components of the unmanned aerial vehicle 200 (e.g., control circuits, communication circuits, etc.) are implemented in the frame 210. A generally rectangular recess (opening) 230 is formed along a vertical axis (e.g., the center) in the frame 210. The payload 240 will be held in the recess 230. It should be noted that the generally rectangular shape of the frame 210 and the recess 230 is merely exemplary. In general, the frame 210 and the recess 230 can have any desired shape.

[0030] The payload 240 may, for example, have a specific shape and / or size that conforms to the shape and / or size of the recess 230. For example, the payload 240 may be a cargo box for carrying one or more cargo items, or a housing for one or more sensors and associated circuitry.

[0031] In addition, eight rotors (propellers) 220 are attached to the frame 210 for propelling the UAV 200. Figure 2 The number of rotors shown in is merely exemplary, and any number N > 2 may be used. Plurality of rotors 220 allows unmanned aerial vehicle 200 to move in any direction and rotate about a vertical axis.

[0032] Return to reference Figure 1 , method 100 comprises autonomously performing steps 102 to 108 described below in flight (i.e., while the first aircraft and the second aircraft are airborne):

[0033] In step 102, a fastening device (fastening element or fastening member) of the first aircraft holds the load in the vertical opening of the first aircraft so that the bottom end of the load can be accessed by the second aircraft. The fastening device can be any device suitable for holding and positioning the load. Two exemplary embodiments of the fastening device will be described below in conjunction with Figures 6 to 7. Figure 9 For example, the fastening device may position the load along a vertical axis such that a bottom end of the load protrudes from a lower end of the first vehicle. Figure 3 An example is shown Figure 2 The load 240 is held by a fastening device (not shown) of the unmanned aerial vehicle 200 so that the lower end of the load 240 protrudes from the lower end of the unmanned aerial vehicle 200. Therefore, the lower end of the load 240 can be contacted by a second aerial vehicle.

[0034] Return to reference Figure 1In step 104, the second aircraft approaches the first aircraft from below to couple the second aircraft's fastening device to the bottom end of the payload. For example, the second aircraft may position itself below the first aircraft and then approach the first aircraft until the second aircraft's fastening device is coupled to the bottom end of the payload. The second aircraft's fastening device may be the same as the first aircraft's fastening device. Figure 4 An exemplary payload exchange system is shown in the payload exchange process. The system includes two similar carrier unmanned aerial vehicles 200-1 and 200-2 (as described above in conjunction with FIG. Figure 2 and Figure 3 The first UAV 200 - 1 initially holds the payload 240 . The second UAV 200 - 2 approaches the first UAV 200 - 1 from below and couples with the protruding bottom end of the payload 240 .

[0035] Return to reference Figure 1 After the fastening device of the second aircraft is coupled to the bottom end of the load, the fastening device of the first aircraft releases the load in step 106. In other words, once the second aircraft is coupled to the load, the load is released by the first aircraft so that only the second aircraft carries the load. Figure 4 In the system, the first UAV 200 - 1 releases the payload 240 after the second UAV 200 - 2 is coupled to the bottom end of the payload 240 .

[0036] In step 108, the fastening device of the second aircraft lowers the load relative to the frame of the second aircraft to move the load to the flight position. After moving the load to the flight position, the second aircraft can begin autonomous flight to the destination location (place, area).

[0037] Method 100 allows for the exchange of (payloads) between two aircraft mid-flight. If the payload includes one or more items of cargo to be transported, and the distance cannot be reached on a single battery charge or fuel load of one of the two aircraft, the travel time can be shortened. Conversely, the travel / delivery distance for transporting the payload can be extended without, for example, increasing the battery capacity of one of the two aircraft. If the payload is (e.g., unique or expensive) sensing equipment used for a sensing mission, the sensing mission can continue after the payload exchange without significant interruption (requiring only a brief interruption for the exchange procedure). Thus, method 100 allows for the rapid and secure transfer of a payload from a first aircraft to a second aircraft. Method 100 can be repeated multiple times during payload transport or during sensing missions between different aircraft. For example, method 100 can be repeated to transfer a payload from a second aircraft to a third aircraft, from a third aircraft to a fourth aircraft, and so on. Consequently, the travel / delivery distance for transporting the payload can be further extended.

[0038] Some basic principles of the proposed technique for autonomously transferring a load from a first aircraft to a second aircraft in flight are described above with reference to method 100, and are described below with reference to Figure 5 A more detailed example of a method 500 for autonomously transferring a load from a first aircraft to a second aircraft in flight is described.

[0039] In method 500, it is assumed that the first aircraft is initially carrying a payload and the second aircraft is initially not carrying any payload. The first aircraft has requested a payload exchange. For example, the first aircraft may request a payload exchange because its battery level is below a threshold or because the battery is predicted to be exhausted. The second aircraft has been dispatched / confirmed to take over the payload. For example, the drone management system (platform) may receive the request from the first aircraft and dispatch the second aircraft. Alternatively, the drone management system may forward the request from the first aircraft and the second aircraft may autonomously confirm the takeover of the payload. Based on the current position (coordinates) and route of the first drone, a rendezvous point (meeting point) for the payload exchange is calculated. For example, the drone management system or the second aircraft may determine the rendezvous point. For example, the current coordinates and heading of the first aircraft may be sent to the second aircraft so that the first aircraft is intercepted by the second aircraft at the calculated rendezvous point.

[0040] Similar to the above description of method 100 , the steps of method 500 are autonomously performed by the first aircraft and the second aircraft in flight.

[0041] When both the first aircraft and the second aircraft approach the rendezvous point, the first aircraft and the second aircraft initially establish a communication channel (eg, via wireless communication technology such as a wireless local area network, a cellular network, or Bluetooth).

[0042] After establishing the communication channel, the second aircraft enters state 502 ("Flying Empty"), where it has no payload prior to the payload exchange procedure. From this state, the second aircraft sends a message to the first aircraft indicating that the exchange procedure can begin ("Ready to Dock" signal). The second aircraft then enters state 506 ("Initiate Docking").

[0043] The first aircraft is in state 504 ("Carrying Flight"), where it is carrying a payload prior to the payload exchange procedure. From this state, the payload exchange procedure is initiated by sending a signal to the second aircraft indicating that the docking procedure can begin (a "Docking Command" signal). The first aircraft then transitions to state 508 ("Waiting for Dockage").

[0044] While in state 506, the second aircraft approaches the first aircraft from below and, once in physical contact with the first aircraft via the payload, sends a "docking" signal to the first aircraft and changes its state to state 510 ("moving to position B").

[0045] In other words, in method 500, autonomously performed on the fly:

[0046] 1) The fastening device of the first aircraft holds the load in the vertical opening of the first aircraft so that the bottom end of the load is accessible by the second aircraft;

[0047] 2) before the second aircraft approaches the first aircraft from below, the second aircraft sends a signal to the first aircraft through a communication channel indicating that the second aircraft is ready to initiate a docking procedure; and

[0048] 3) The second aircraft approaches the first aircraft from below after receiving approval of the docking procedure from the first aircraft through a communication channel to couple the fastening device of the second aircraft to the bottom end of the payload.

[0049] While in state 508, the first aircraft changes its flight controls to await docking procedures. For example, the rotors may enter docking mode. In docking mode, a predetermined subset of rotors operates at reduced power or is shut down, while another subset operates at increased power. An optional navigation system may be enabled. Upon receiving the "Docking" signal, the first aircraft transitions to state 512 ("Waiting 0") as the two aircraft are physically connected via the payload.

[0050] During docking, the two aircraft are precisely positioned relative to each other, and their rotors operate in a coordinated manner. For example, the second aircraft might deactivate or reduce the power of the rotors diametrically opposite those of the first aircraft. This coordinated operation of the two aircraft's rotors reduces the downwind exposure of the active propellers of the second aircraft approaching from below. To compensate for the loss of lift, the remaining active propellers are operated at increased power. For example, the first aircraft can signal the second aircraft which rotors are operating at increased and / or decreased power and / or which rotors are deactivated.

[0051] In other words, in method 500 , further autonomously performed on the fly:

[0052] 4) as the second aircraft approaches the first aircraft from below, the first aircraft operates a first subset of the plurality of rotors attached to the frame of the first aircraft at reduced power or zero power;

[0053] 5) as the second aircraft approaches the first aircraft from below, the first aircraft operates a second subset of the plurality of rotors attached to the frame of the first aircraft at increased power;

[0054] 6) The first aircraft sends a signal of information about the first subset of rotors and the second subset of rotors to the second aircraft through the communication channel.

[0055] 7) the second aircraft operates the rotors attached to the frame of the second aircraft at reduced power or zero power in a position vertically below a second subset of the rotors of the first aircraft; and

[0056] 8) The second aircraft operates the rotors attached to the frame of the second aircraft at the increased power in a position vertically below the first subset of the rotors of the first aircraft.

[0057] In state 510, the second aircraft moves from its initial coupling position at the bottom end of the payload to docking position B on the payload. At position B, the payload is securely coupled to the second aircraft. To move to position B, the second aircraft lowers the payload relative to the second aircraft's frame. Once position B is reached, a signal is sent to the first aircraft indicating that the second aircraft is ready to take over the payload ("reached position B" signal).

[0058] In other words, in method 500 , further autonomous execution is performed on the fly:

[0059] 9) after the fastening device of the second vehicle is coupled to the bottom end of the payload, the fastening device of the second vehicle lowers the payload relative to the frame of the second vehicle to move the payload into the docked position; and

[0060] 10) After the second aircraft has moved the payload to the docking position, the second aircraft sends a signal to the first aircraft via the communication channel that the second aircraft is ready to take over the payload.

[0061] As the second aircraft moves toward docking location B, the first aircraft is in state 512. At this point in the payload exchange process, the first and second aircraft are coupled / interconnected. In state 512, the first aircraft stabilizes the flight of the interconnected system. Once the second aircraft has reached location B, the first aircraft signals its readiness to exchange lift with the second aircraft ("Ready to Exchange Lift" signal).

[0062] In other words, in method 500 , when the second aircraft is interconnected with the first aircraft via the payload, autonomously further performs in flight:

[0063] 11) The first aircraft performs flight stabilization of the first aircraft and the second aircraft.

[0064] Once at position B, the second aircraft moves to state 514 ("Wait 1") and waits for a signal from the first aircraft to exchange lift.

[0065] Once the first aircraft has signaled the second aircraft to increase its lift to take over the weight of the payload via the "Ready to Exchange Lift" signal, the first aircraft moves to state 516 ("Maintain Altitude"), in which it adjusts its own lift to maintain its current altitude. The first aircraft reduces its lift by reducing the power of the plurality of rotors attached to its frame (e.g., by reducing the rotational speed of its rotors). Once the first aircraft has reduced its lift to a level that only carries its own weight, it signals to the second aircraft that the lift exchange is complete ("Lift Exchange Complete" signal).

[0066] Upon receiving the signal to exchange lift from the first aircraft, the second aircraft moves to state 518 ("Increasing Lift") and begins increasing its lift until the first aircraft signals it to stop via the "Lift Exchange Complete" signal. The second aircraft now generates enough lift to maintain the second aircraft's current altitude while carrying the payload. The second aircraft now takes over responsibility for payload stabilization and signals this to the first aircraft ("Accepting Responsibility" signal).

[0067] After signaling the completion of the lift exchange to the second aircraft via the "Lift Exchange Complete" signal, the first aircraft moves to state 520 ("Exchange Response"). In state 520, the first aircraft relinquishes payload stabilization, which is handed over to the second aircraft. Once the first aircraft receives a signal from the second aircraft indicating that the second aircraft has now taken over responsibility for payload stabilization, the first aircraft moves to state 524 ("Undocking") to initiate the undocking procedure. During the undocking process, the first aircraft's securing device may initially lower the payload relative to the frame (i.e., effectively raise itself relative to the payload). In other words, the first aircraft moves to the top of the payload before undocking from the payload.

[0068] Once the undocking process is complete, the first aircraft sends a corresponding message to the second aircraft ("Undocking Complete" signal). Furthermore, the first aircraft enters state 528 ("Flying Empty"), indicating that it is unloaded (similar to the initial state 502 of the second aircraft). The first aircraft is now uncoupled from the second aircraft and the payload.

[0069] In other words, in method 500 , after the second aircraft sends a signal to the first aircraft that the second aircraft is ready to take over the payload, the method further autonomously performs in flight:

[0070] 12) the first aircraft reduces power to a plurality of rotors attached to a frame of the first aircraft so that the rotors generate lift sufficient to maintain only the current altitude of the first aircraft;

[0071] 13) The second aircraft increases power to a plurality of rotors attached to the frame of the second aircraft such that the rotors generate lift for maintaining the current altitude of the second aircraft while carrying the payload.

[0072] 14) after reducing the power of the rotor, the first aircraft sends a signal to the second aircraft via the communication channel to take over the load, so that the rotor generates lift sufficient to maintain the current altitude of only the first aircraft; and

[0073] 15) The fastening device of the first aircraft releases the load, wherein the fastening device of the first aircraft can reduce the load relative to the frame of the first aircraft before releasing the load.

[0074] After the second aircraft signals to the first aircraft that it has taken over the responsibility for stabilizing the payload, it moves to state 522 ("Hold Attitude"). In state 522, the second aircraft maintains its altitude / position as the first aircraft begins to undocking from the payload.

[0075] The second aircraft then moves to state 526 ("Wait 2") and waits for the first aircraft to complete undocking from the payload.

[0076] Once the first vehicle has signaled the completion of undocking via the "Undocking Complete" signal, the second vehicle moves to state 530 to move the payload to flight position A. To move the payload to flight position A, the second vehicle's fastening device lowers the payload relative to the second vehicle's frame. In position A, the payload's center of mass, and therefore the entire system consisting of the second vehicle and payload, is lowered, resulting in better flight stability. Furthermore, lowering the payload prepares for an optional further payload exchange with a third vehicle. In some alternative examples, docking position B may be identical to the flight position, allowing state 530 to be omitted.

[0077] After dropping the payload, the second aircraft moves to state 532 ("Carrying Flight"), indicating that it is now carrying the payload. The payload exchange cycle is now complete, leaving the first aircraft in the same state as the second aircraft was in before the payload exchange procedure, and the second aircraft in the same state as the first aircraft was in before the payload exchange procedure.

[0078] After the first aircraft has been decoupled from the payload, both aircraft can again use their rotors independently of each other.

[0079] In other words, in method 500 , after the first aircraft sends a signal to the second aircraft to take over the load, the following operations are further performed autonomously in flight:

[0080] 16) The second aircraft performs flight stabilization of the first aircraft and the second aircraft until the fastening device of the first aircraft releases the load;

[0081] 17) When the fastening device of the first aircraft releases the load, the second aircraft maintains the current altitude of the second aircraft.

[0082] 18) The first aircraft sends a signal to the second aircraft through a communication channel indicating that the fastening device of the first aircraft has released the load; and

[0083] 19) The second aircraft then begins moving the payload into flight position.

[0084] from Figure 5 It can be seen that the first aircraft is initially responsible for flight stabilization until state 520. The second aircraft then takes over responsibility for flight stabilization.

[0085] To perform the above-described payload exchange procedure, each of the first and second aircraft includes control circuitry configured to control the respective one of the first and second aircraft to autonomously perform the respective steps described above in flight. For example, the respective control circuitry may be a single dedicated processor, a single shared processor, or multiple individual processors (some or all of which may be shared), digital signal processor (DSP) hardware, application-specific integrated circuit (ASIC), or field-programmable gate array (FPGA). Each control circuitry may optionally be coupled to, for example, read-only memory (ROM), random access memory (RAM), and / or non-volatile memory for storing software. The aircraft may also include other hardware, conventional and / or custom.

[0086] The above describes in detail the process of autonomously transferring a load from a first aircraft to a second aircraft in flight. The following paragraphs will focus on the structure of the aircraft's fastening device. In particular, the following will be combined with Figures 6a to 9 Two examples of implementing the fastening device are described in detail.

[0087] Figure 6a A partial representation of an aircraft 600 is shown that includes a plurality of rotatable worms as fastening means. For simplicity, Figure 6a Only one rotatable worm 620 is depicted. However, it should be noted that any number N ≥ 2 of rotatable worms may be used.

[0088] Similar to the unmanned aerial vehicle 200 described above, the aerial vehicle 600 includes a frame (fuselage) 610 having a vertical opening 630 for receiving a payload 640. The vertical opening 630 is formed along a vertical axis in the center of the frame 610. It should be noted that the generally rectangular shape of the frame 610 and the vertical opening 630 (recess) is merely exemplary. In general, the frame 610 and the vertical opening 630 may take on any desired shape. Although in Figure 6a Not explicitly shown, a plurality of rotors are attached to the frame 610 to allow the vehicle 600 to move in any direction and rotate about a vertical axis.

[0089] like Figure 6a The exemplary rotatable worm 620 shown is a plurality of rotatable worms disposed in the frame such that the rotatable worms protrude from the sidewalls of the vertical opening 630. For example, the rotatable worms may be disposed at an inner corner of the frame 610, ie, a corner of the vertical opening 630.

[0090] The aircraft 600 also includes at least one controllable drive 650 (eg, an electric motor) for the plurality of rotatable worm gears. The at least one drive 650 is configured to rotate the plurality of rotatable worm gears. Figure 6a The illustrated example shows a plurality of rotatable worms 620 , with the at least one driver 650 being mechanically coupled to the plurality of rotatable worms.

[0091] The load 640 comprises a counterpart for engaging with the rotatable worm. For simplicity, Figure 6a 6. The counterpart of the rotatable worm 620 is shown as an example. The counterpart for engaging with the rotatable worm 620 is a rack 641 located on the outer vertical surface of the load 640. Since the rotatable worm 620 is located at a corner of the vertical opening 630, the rack 641 is located at the outer corner of the load 640. However, it should be noted that the rack 641 does not need to be located at a corner of the load 640. A plurality of racks are located on the outer vertical surface of the load 640 at positions corresponding to the positions of the plurality of rotatable worms on the sidewall of the vertical opening 630.

[0092] When the plurality of rotatable worm gears engage the plurality of rack gears, the load is securely coupled to the frame 610 of the aircraft 600, and thus to the aircraft 600. Furthermore, by rotating the plurality of rotatable worm gears, the vertical position of the load 640 relative to the frame 610 is adjustable. Accordingly, by rotating the plurality of rotatable worm gears, the load 640 can be lowered relative to the frame 610 in accordance with the method for autonomously transferring a load in flight as described above. Due to the presence of the plurality of rack gears at the load, the position of the load relative to the frame of the first aircraft or the second aircraft can be adjusted by rotating the plurality of rotatable worm gears of the respective one of the first aircraft and the second aircraft in the method described above.

[0093] It should be noted that aircraft 600 may also include other conventional and / or custom hardware. For example, aircraft 600 may include control circuitry, communication circuitry, and the like. In particular, aircraft 600 may include control circuitry configured to control aircraft 600 to autonomously perform the method steps described above for one of the first aircraft and the second aircraft during flight. Additional components of aircraft 600 may be disposed within frame 610.

[0094] Figure 6b A side view is shown for illustrating the engagement of the rotatable worm 620 and the rack 641. Figure 6b It can be seen that the rotatable worm 620 protrudes from the side wall 611 of the frame 610 and enters the vertical opening 630 so that the rack 641 can directly engage with the worm 620.

[0095] An alternative embodiment using an additional worm gear 621 is Figure 6c 6. The worm gear 621 is driven (drivable) by the worm 620. Both the worm 620 and the worm gear 621 are arranged in the frame 610 so that only the worm gear 621 protrudes from the side wall 611 of the frame 610 and enters the vertical opening 630. Therefore, the rack 641 is (indirectly) engaged with the worm 620 through the worm gear 621.

[0096] Figures 7 to 9 A further exemplary embodiment of a fastening device is shown. Figures 7 to 9 In the example of , the fastening means is implemented by a plurality of bolts. For example, the embodiments of the fastening means described below can be used instead of the rotatable worm of the aircraft 600 and the rack of the load 640.

[0097] Figure 7 A side view is shown of a situation in which a first aircraft 700 - 1 and a second aircraft 700 - 1 are coupled to a payload 740 during a payload exchange procedure according to the proposed technology.

[0098] The first aircraft 700-1 and the second aircraft each include a plurality of bolts. Figure 7 Only two bolts 720-1 and 720-2 of the first aircraft 700-1 and two bolts 720-5 and 720-6 of the second aircraft 700-2 are visible. The bolts of the first aircraft 700-1 are attached to the side walls of the vertical opening in the frame 710-1 of the first aircraft 700-1, while the bolts of the second aircraft 700-2 are attached to the side walls of the vertical opening 730-2 in the frame 710-2 of the second aircraft 700-2.

[0099] The load 740 comprises a plurality of rotatable cylinders. Figure 7 Only the rotatable columns 741-1 and 741-2 are visible. Each of the plurality of rotatable columns is rotatably held relative to the load 740 by a corresponding mounting structure (suspension). Figure 8 This can be seen better by Figure 8 Shown Figure 7 Bottom view of the situation shown. Each of the rotatable posts 741 - 1 , 741 - 2 , 741 - 3 and 741 - 4 is rotatably held relative to the load 740 by a corresponding mounting structure 742 - 1 , 742 - 2 , 742 - 3 and 742 - 4 .

[0100] To keep it simple, Figure 8 Four bolts 720-5, 720-6, 720-7, and 720-8 are depicted at the corners of the vertical opening 730-2. However, it should be noted that any number N≥2 bolts may be used.

[0101] Each of the cylinders 741-1, 741-2, 741-3 and 741-4 includes a cylinder surface having a circumferential recess for engaging with bolts of the first and second aircraft 700-1. Figure 8 As shown, the bolts 720-5, 720-6, 720-7 and 720-8 of the second aircraft 700-2 are engaged with the circumferential recesses of the columns 741-1, 741-2, 741-3 and 741-4. Similarly, the circumferential recesses of the columns 741-1, 741-2, 741-3 and 741-4 are engaged with the bolts of the first aircraft 700-1 (as shown in FIG. Figure 7 720 - 1 and 720 - 2 in FIG.

[0102] The columns 741-1, 741-2, 741-3 and 741-4 can be rotated by the second aircraft 700-2 by applying force along the column axis through the bolts 720-5, 720-6, 720-7 and 720-8 of the second aircraft 700-2. The column axis extends along the length direction of the columns 741-1, 741-2, 741-3 and 741-4. The column axes Z1 and Z2 of the columns 741-1 and 741-2 are Figure 7 As shown in FIG.

[0103] When the second vehicle 700-2 approaches the load from below, the bolts 720-5, 720-6, 720-7, and 720-8 of the second vehicle 700-2 engage with the circumferential notches of the columns 741-1, 741-2, 741-3, and 741-4, and apply a force in a vertical direction (e.g., along the column axis) to the columns 741-1, 741-2, 741-3, and 741-4. The circumferential notches of the columns 741-1, 741-2, 741-3, and 741-4 are formed so that when the force is applied to the columns 741-1, 741-2, 741-3, and 741-4, the columns 741-1, 741-2, 741-3, and 741-4 begin to rotate. Furthermore, the circumferential notches of the columns 741-1, 741-2, 741-3, and 741-4 are formed so that the bolts 720-5, 720-6, 720-7, and 720-8 of the second aircraft 700-2 engage with the notches in the coupled position. Furthermore, the circumferential notches of the columns 741-1, 741-2, 741-3, and 741-4 are formed so that the bolts of the first aircraft 700-1 are loosened from the notches due to the rotation of the columns 741-1, 741-2, 741-3, and 741-4.

[0104] Thus, the load 740, which was initially secured to the first vehicle 700-1 by the bolts of the first vehicle 700-1 and the circumferential recesses of the columns 741-1, 741-2, 741-3, and 741-4, can be decoupled from the first vehicle 700-1 and secured to the second vehicle 700-1 by the bolts 720-5, 720-6, 720-7, and 720-8 of the second vehicle 700-2 and the circumferential recesses of the columns 741-1, 741-2, 741-3, and 741-4.

[0105] An exemplary shape for the circumferential recess of column 741-1 is shown in FIG. Figure 9 As shown in FIG. Figure 9 The expanded cylinder surface 744 of cylinder 741-1 is shown to highlight the shape of the circumferential recess 745. Figure 9 In the embodiment, the cylindrical surface 744 is expanded for more than one week, so that Figure 9 The right part and Figure 9The left portion of FIG. 74 shows the same portion of the cylinder surface 744. Note that in some examples, the circumferential recesses in the plurality of rotatable cylinders may exhibit different Figure 9 The shape / form shown is used to achieve the functions described above.

[0106] Due to the vertical groove 746 in the circumferential recess 745 , the bolt 720 - 1 of the first vehicle 700 - 1 is initially engaged with the circumferential recess 745 in the coupled position.

[0107] As the second vehicle 700-2 approaches the load 740 from below, the bolt 720-5 enters the circumferential recess 745 at the (e.g., funnel-shaped) inlet portion 747. Due to the vertical ascent of the circumferential recess 745, if the second vehicle 700-2, and therefore the bolt 720-1, continues to apply force along the column axis Z1, the column 741-1 begins to rotate. Consequently, the bolt 720-1 of the first vehicle 700-1 moves out of the vertical groove 746 of the circumferential recess 745 and toward the outlet portion 748 of the circumferential recess 745, decoupling the load 740 from the first vehicle 700-1. Meanwhile, the bolt 720-5 of the second vehicle 700-2 moves toward the vertical groove 746 in the circumferential recess 745, engaging the bolt 720-5 of the second vehicle 700-2 with the first circumferential recess 745 in the coupled position (i.e., the flight position of the load 740).

[0108] As the columns 741 - 1 , 741 - 2 , 741 - 3 and 741 - 4 rotate, the bolts of the first and second vehicles 700 - 1 and 700 - 2 slide along their respective circumferential notches.

[0109] When the bolt of the aircraft is engaged with the circumferential notch of the rotatable column in the coupling position, the load is safely coupled to the frame. In addition, due to the vertically rising shape of the circumferential notch, the vertical position of the load is adjustable relative to the frame of the aircraft.

[0110] If the bolt and column are combined as above Figures 7 to 9 The description is used for the mechanical coupling of the vehicle and the payload, Figure 5 The various states of the illustrated method 500 are adapted as follows:

[0111] In state 506 ("Initiate docking"), the second vehicle approaches the first vehicle from below until the bolt enters the entry portion of the circumferential recess in the column of the load (eg, Figure 9 The second aircraft then sends a "docking" signal to the first aircraft and changes to state 510 ("moving to position B").

[0112] Position B in state 510 indicates that the bolts are initially in mechanical contact with the post such that they can apply at least some normal force (force along the axis of the post) to the post to reach the coupled position.

[0113] State 530 ("Move to Position A") may be omitted, skipped, or simply continued to state 532 without action, since the second vehicle is already in position A (ie, the coupled position) due to column mechanics.

[0114] At state 524 ("Undocking"), the second vehicle descends vertically. No further mechanical undocking is required, as this is implicitly achieved when the column rotates at state 518. At the end of state 518, the bolts are located at the exit of the circumferential recess in the loaded column (e.g., Figure 9 The bolt can thus be pulled out by moving it upwards.

[0115] The aircraft described above may be, for example, a drone, such as a multi-rotor drone.

[0116] The following examples relate to further embodiments:

[0117] (1) A method for autonomously transferring a load from a first aircraft to a second aircraft in flight, wherein each of the first aircraft and the second aircraft comprises a frame having a vertical opening for receiving the load, wherein a plurality of rotors are attached to the frame, the method comprising autonomously performing the following in flight:

[0118] The fastening device of the first aircraft holds the load in the vertical opening of the first aircraft so that a bottom end of the load is accessible by the second aircraft;

[0119] The second aircraft approaches the first aircraft from below to couple the fastening device of the second aircraft to the bottom end of the payload;

[0120] After the fastening device of the second aircraft is coupled to the bottom end of the load, the fastening device of the first aircraft releases the load; and

[0121] The fastening device of the second aircraft lowers the load relative to the frame of the second aircraft to move the load into the flight position.

[0122] (2) The method according to (1), wherein the method further comprises autonomously performing the following in flight:

[0123] The first aircraft and the second aircraft initially establish a communication channel.

[0124] (3) The method according to (2), wherein the method further comprises autonomously performing the following in flight:

[0125] The second aircraft sends a signal to the first aircraft via the communication channel that the second aircraft is ready to initiate a docking procedure before approaching the first aircraft from below, wherein the second aircraft approaches the first aircraft from below after receiving approval of the docking procedure from the first aircraft via the communication channel.

[0126] (4) The method according to (3), wherein the method further comprises autonomously performing the following in flight:

[0127] As the second aircraft approaches the first aircraft from below, the first aircraft operates a first subset of the plurality of rotors attached to the frame of the first aircraft at reduced power or zero power;

[0128] As the second aircraft approaches the first aircraft from below, the first aircraft operates a second subset of the plurality of rotors attached to the frame of the first aircraft at increased power; and

[0129] The first aircraft sends a signal to the second aircraft over a communication channel regarding information about the first subset of rotors and the second subset of rotors.

[0130] (5) The method according to (4), wherein the method further comprises autonomously performing the following in flight:

[0131] the second aircraft operating the rotors attached to the frame of the second aircraft at a position vertically below a second subset of the rotors of the first aircraft at reduced power or zero power; and

[0132] The second aircraft operates rotors attached to the frame of the second aircraft at increased power in a position vertically below the first subset of rotors of the first aircraft.

[0133] (6) The method according to (4) or (5), wherein the method further comprises autonomously performing the following in flight:

[0134] After the fastening device of the second aircraft is coupled to the bottom end of the payload, the fastening device of the second aircraft lowers the payload relative to the frame of the second aircraft to move the payload to the docking position.

[0135] (7) The method according to (6), wherein the method further comprises autonomously performing the following when the second aircraft is interconnected with the first aircraft via the payload:

[0136] The first aircraft performs flight stabilization of the first aircraft and the second aircraft.

[0137] (8) The method of (6) or (7), wherein the method further comprises autonomously performing the following in flight after the payload is moved to the docking position by the second aircraft:

[0138] The second aircraft sends a signal to the first aircraft through the communication channel that the second aircraft is ready to take over the payload.

[0139] (9) The method according to (8), wherein the method further comprises autonomously performing the following in flight after the second aircraft sends a signal to the first aircraft indicating that the second aircraft is ready to take over the payload:

[0140] The first aircraft depowers a plurality of rotors attached to a frame of the first aircraft such that the rotors generate lift that maintains only the current altitude of the first aircraft; and

[0141] The second aircraft increases power to a plurality of rotors attached to the frame of the second aircraft such that the rotors generate lift used to maintain the current altitude of the second aircraft while carrying a load.

[0142] (10) The method of (9), wherein the method further comprises, after reducing the power of the rotors so that the rotors generate sufficient lift to maintain the current altitude of only the first aircraft, autonomously performing the following in flight:

[0143] The first aircraft sends a signal to the second aircraft via a communication channel to take over the load; and

[0144] The fastening device of the first aircraft releases the load.

[0145] (11) The method of (10), wherein the fastening device of the first aircraft reduces the load relative to the frame of the first aircraft before releasing the load.

[0146] (12) The method according to (10), wherein the method further comprises autonomously performing the following in flight after the first aircraft sends a signal to the second aircraft to take over the load:

[0147] The second aircraft performs flight stabilization of the first aircraft and the second aircraft until the fastening device of the first aircraft releases the load.

[0148] (13) The method according to (12), wherein the method further comprises autonomously performing the following in flight:

[0149] When the fastening device of the first aircraft releases the load, the second aircraft maintains the current altitude of the second aircraft.

[0150] (14) The method according to (13), wherein the method further comprises autonomously performing the following in flight:

[0151] The first aircraft sends a signal to the second aircraft via a communication channel indicating that the fastening device of the first aircraft has released the load; and / or

[0152] The second aircraft then begins moving the payload into flight position.

[0153] (15) A method according to (1) to (14), wherein each fastening device of the first aircraft and the second aircraft includes a plurality of rotatable worm gears arranged in the frame of the corresponding one of the first aircraft and the second aircraft, and wherein the load includes a plurality of racks for engaging with the plurality of rotatable worm gears of the first aircraft and the second aircraft, so that the position of the load relative to the frame of the corresponding one of the first aircraft and the second aircraft is adjustable by rotating the plurality of rotatable worm gears of the corresponding one of the first aircraft and the second aircraft.

[0154] (16) A method according to any one of (1) to (14), wherein each fastening device of the first aircraft and the second aircraft includes a plurality of bolts, wherein the load includes a plurality of rotatable cylinders, wherein the plurality of cylinders each include a cylinder surface, the cylinder surface having a circumferential recess, the circumferential recess being used to engage with the plurality of bolts of the first aircraft and the second aircraft, so that the aircraft cylinder can be rotated by the second aircraft applying a force along the cylinder axis via the bolts of the second aircraft, and wherein the bolts of the second aircraft engage with the recesses at a coupled position, and when the cylinder rotates, the bolts of the first aircraft are loosened from the recesses.

[0155] (17) A system comprising a first aircraft and a second aircraft, wherein each of the first aircraft and the second aircraft comprises a frame having a vertical opening for receiving a payload, wherein a plurality of rotors are attached to the frame, wherein each of the first aircraft and the second aircraft comprises a control circuit configured to control a respective one of the first aircraft and the second aircraft to autonomously perform the following in flight:

[0156] The fastening device of the first aircraft holds the load in the vertical opening of the first aircraft so that a bottom end of the load is accessible by the second aircraft;

[0157] The second aircraft approaches the first aircraft from below to couple the fastening device of the second aircraft to the bottom end of the payload;

[0158] After the fastening device of the second aircraft is coupled to the bottom end of the load, the fastening device of the first aircraft releases the load; and

[0159] The fastening device of the second aircraft lowers the load relative to the frame of the second aircraft to move the load into the flight position.

[0160] (18) An aircraft, comprising:

[0161] a frame having a vertical opening for receiving a load;

[0162] a plurality of rotors, the rotors being attached to the frame;

[0163] a plurality of rotatable worm gears disposed in the frame, wherein the worm gears are engageable with a plurality of racks of the load to secure the load; and

[0164] At least one controllable drive is provided for the plurality of rotatable worms, wherein the drive is configured to rotate the plurality of rotatable worms to adjust a vertical position of the payload relative to the frame.

[0165] (19) An aircraft, comprising:

[0166] a frame having a vertical opening for receiving a load;

[0167] a plurality of rotors attached to the frame; and

[0168] A plurality of bolts are attached to the sidewalls of the vertical opening, wherein the bolts are engageable with corresponding notches in the cylinder surfaces of the plurality of cylinders of the load to secure the load, wherein the cylinders of the load can be rotated by the bolts by applying a force along the cylinder axis.

[0169] The aspects and features mentioned and described in conjunction with one or more of the foregoing detailed examples and figures may also be combined with one or more other examples to replace similar features of the other examples, or to otherwise introduce the features into the other examples.

[0170] The description and drawings merely illustrate the principles of the present invention. Furthermore, all examples described herein are primarily intended to be illustrative only, to aid the reader in understanding the principles of the present invention and the concepts contributed by the inventors to advance the art. All statements herein reciting principles, aspects, and examples of the present invention, as well as specific examples thereof, are intended to encompass their equivalents.

[0171] For example, a block diagram may illustrate a high-level circuit diagram that implements the principles of the present invention. Similarly, a flow chart, a flowchart, a state transition diagram, a pseudo code, etc. may represent various processes, operations, or steps that may be substantially embodied in a non-transitory machine-readable medium (e.g., a floppy disk, DVD, Blu-ray, CD, ROM, PROM, and EPROM, EEPROM, or flash memory) and thus performed by a processor or programmable hardware, whether or not such processor or programmable hardware is explicitly shown.

[0172] The methods disclosed in the specification or claims can be implemented by a device having means for performing each corresponding action of these methods.

[0173] It should be understood that the disclosure of multiple actions, processes, operations, steps or functions disclosed in the specification or claims should not be interpreted as being in a specific order unless otherwise explicitly or implicitly stated, for example, for technical reasons. Therefore, the disclosure of multiple actions or functions should not limit them to a specific order unless such actions or functions are not interchangeable for technical reasons. In addition, in some examples, a single action, function, process, operation or step may include or may be decomposed into multiple sub-actions, sub-functions, sub-processes, sub-operations or sub-steps. Such sub-actions may be included and part of the disclosure of this single action unless expressly excluded.

[0174] In addition, the following claims are hereby incorporated into the detailed description, where each claim can stand on its own as a separate example. Although each claim can stand on its own as a separate example, it should be noted that although a dependent claim can refer to a specific combination with one or more other claims in a claim, other examples can also include a combination of the dependent claim with the subject matter of each other dependent claim or independent claim. Such combinations are expressly proposed herein unless it is stated that a specific combination is not intended. In addition, even if a claim does not directly refer to an independent claim, it is intended that the features of that claim be included in any other independent claim.

Claims

1. A method (100, 500) for autonomously transferring a load from a first aircraft to a second aircraft in flight, wherein: Each of the first and second aircraft includes a frame having a vertical opening for receiving the payload, wherein a plurality of rotors are attached to the frame, the method comprising autonomously performing the following operations in flight: The fastening device of the first aircraft holds the load in the vertical opening of the first aircraft so that a bottom end of the load can be accessed by the second aircraft; The second aircraft approaches the first aircraft from below to couple the fastening device of the second aircraft to the bottom end of the payload; After the fastening device of the second aircraft is coupled to the bottom end of the load, the fastening device of the first aircraft releases the load; and the securing device of the second aircraft lowering the load relative to the frame of the second aircraft to move the load into a flight position; wherein each of the fastening devices of the first and second aircraft comprises a plurality of rotatable worm gears disposed in a frame of a respective one of the first and second aircraft, and wherein the load comprises a plurality of racks for engaging with the plurality of rotatable worm gears of the first and second aircraft such that a position of the load relative to the frame of the respective one of the first and second aircraft is adjustable by rotating the plurality of rotatable worm gears of the respective one of the first and second aircraft; or wherein each of the fastening devices of the first and second aircraft comprises a plurality of bolts, wherein the load comprises a plurality of rotatable cylinders, wherein each of the plurality of cylinders comprises a cylinder surface having a circumferential recess, wherein the circumferential recess is adapted to engage with the plurality of the bolts of the first and second aircraft, such that the cylinders can be rotated by the second aircraft by applying a force along the cylinder axis via the bolts of the second aircraft, and wherein the bolts of the second aircraft engage with the recesses in a coupled position and the bolts of the first aircraft release from the recesses upon rotation of the cylinders.

2. The method (100, 500) according to claim 1, wherein The method further comprises autonomously performing the following operations in flight: The first aircraft and the second aircraft initially establish a communication channel.

3. The method (100, 500) according to claim 2, wherein: The method further comprises autonomously performing the following operations in flight: The second aircraft sends a signal to the first aircraft via the communication channel that the second aircraft is ready to start a docking procedure before approaching the first aircraft from below, The second aircraft approaches the first aircraft from below after receiving approval of the docking procedure from the first aircraft via the communication channel.

4. The method (100, 500) according to claim 3, wherein: The method further comprises autonomously performing the following operations in flight: the first aircraft operating a first subset of the plurality of rotors attached to the frame of the first aircraft at reduced power or zero power as the second aircraft approaches the first aircraft from below; the first aircraft operating a second subset of the plurality of rotors attached to the frame of the first aircraft at increased power as the second aircraft approaches the first aircraft from below; as well as The first aircraft sends a signal regarding the first subset of rotors and the second subset of rotors to the second aircraft via the communication channel.

5. The method (100, 500) according to claim 4, wherein The method further comprises autonomously performing the following operations in flight: the second aircraft operating the rotors attached to the frame of the second aircraft at a position vertically below the second subset of the rotors of the first aircraft at reduced power or zero power; as well as The second aircraft operates rotors attached to the frame of the second aircraft at a position vertically below the first subset of rotors of the first aircraft at increased power.

6. The method (100, 500) according to claim 4, wherein The method further comprises autonomously performing the following operations in flight: After the fastening device of the second vehicle is coupled to the bottom end of the payload, the fastening device of the second vehicle lowers the payload relative to the frame of the second vehicle to move the payload to a docked position.

7. The method (100, 500) according to claim 6, wherein The method further comprises autonomously performing the following operations in flight while the second aircraft is interconnected with the first aircraft via the payload: The first aircraft performs flight stabilization of the first aircraft and the second aircraft.

8. The method (100, 500) according to claim 6, wherein The method further comprises autonomously performing the following operations in flight after the payload is moved to the docking position by the second aircraft: The second aircraft sends a signal to the first aircraft via the communication channel indicating that the second aircraft is ready to take over the payload.

9. The method (100, 500) according to claim 8, wherein The method further includes autonomously performing the following operations in flight after the second aircraft sends a signal to the first aircraft indicating that the second aircraft is ready to take over the payload: The first aircraft depowers the plurality of rotors attached to the frame of the first aircraft so that the rotors generate lift only to maintain a current altitude of the first aircraft; and The second aircraft increases power to the plurality of rotors attached to the frame of the second aircraft so that the rotors generate lift for maintaining a current altitude of the second aircraft while carrying the payload.

10. The method (100, 500) according to claim 9, wherein: The method further includes autonomously performing the following operations in flight after reducing power to the rotor so that the rotor generates sufficient lift to merely maintain the current altitude of the first aircraft: The first aircraft sends a signal to the second aircraft via the communication channel to take over the payload; and The fastening device of the first aircraft releases the load.

11. The method (100, 500) according to claim 10, wherein: Before releasing the load, the fastening device of the first aircraft lowers the load relative to the frame of the first aircraft.

12. The method (100, 500) according to claim 10, wherein: The method further includes autonomously performing the following operations in flight after the first aircraft sends a signal to the second aircraft to take over the payload: The second aircraft performs flight stabilization of the first aircraft and the second aircraft until the fastening device of the first aircraft releases the load.

13. The method (100, 500) according to claim 12, wherein: The method further comprises autonomously performing the following operations in flight: When the fastening device of the first aircraft releases the load, the second aircraft maintains the current altitude of the second aircraft.

14. The method (100, 500) according to claim 13, wherein: The method further comprises autonomously performing the following operations in flight: The first aircraft sends a signal to the second aircraft via the communication channel that the fastening device of the first aircraft releases the load; and / or The second aircraft then begins moving the payload to the flight position.

15. A system comprising a first aircraft (200-1) and a second aircraft (200-2), wherein: Each of the first aircraft (200-1) and the second aircraft (200-2) includes a frame having a vertical opening for receiving a payload (240), wherein a plurality of rotors are attached to the frame, wherein each of the first aircraft (200-1) and the second aircraft (200-2) includes a control circuit configured to control a respective one of the first aircraft (200-1) and the second aircraft (200-2) to autonomously perform the following operations in flight: The fastening device of the first aircraft (200-1) holds the load (240) in the vertical opening of the first aircraft (200-1) so that the bottom end of the load (240) can be contacted by the second aircraft (200-2); The second aircraft (200-2) approaches the first aircraft (200-1) from below to couple the fastening device of the second aircraft (200-2) to the bottom end of the load (240); After the fastening device of the second aircraft (200-2) is coupled to the bottom end of the load (240), the fastening device of the first aircraft (200-1) releases the load (240); and The fastening device of the second aircraft (200-2) lowers the load (240) relative to the frame of the second aircraft (200-2) to move the load (240) to a flying position; wherein each of the fastening devices of the first aircraft (200-1) and the second aircraft (200-2) comprises a plurality of rotatable worms arranged in a frame of a corresponding one of the first aircraft (200-1) and the second aircraft (200-2), and wherein the load (240) comprises a plurality of racks for engaging with the plurality of rotatable worms of the first aircraft (200-1) and the second aircraft (200-2), such that the position of the load (240) relative to the frame of the corresponding one of the first aircraft (200-1) and the second aircraft (200-2) is adjustable by rotating the plurality of rotatable worms of the corresponding one of the first aircraft (200-1) and the second aircraft (200-2); or wherein each of the fastening devices of the first aircraft (200-1) and the second aircraft (200-2) comprises a plurality of bolts, wherein the load (240) comprises a plurality of rotatable cylinders, wherein each of the plurality of cylinders comprises a cylinder surface, wherein the cylinder surface has a circumferential recess, wherein the circumferential recess is used to engage with the plurality of bolts of the first aircraft (200-1) and the second aircraft (200-2), so that the cylinder can be rotated by the second aircraft (200-2) by applying a force along the cylinder axis via the bolts of the second aircraft (200-2), and wherein the bolts of the second aircraft (200-2) engage with the recesses in a coupled position, and when the cylinder is rotated, the bolts of the first aircraft (200-1) are released from the recesses.

16. An aircraft (600), comprising: a frame (610) having a vertical opening (630) for receiving a load (640); a plurality of rotors attached to the frame (610); A plurality of rotatable worms (620) are arranged in a frame (610), wherein: The worm (620) is capable of engaging with a plurality of racks (641) of the load (640) to secure the load (640); as well as At least one controllable drive (650) for the plurality of rotatable worm screws (620), wherein the drive is configured to rotate the plurality of rotatable worm screws (620) to adjust the vertical position of the load (640) relative to the frame (610).

17. An aircraft (700-2), comprising: a frame (710-2) having a vertical opening (730-2) for receiving a load (740); a plurality of rotors attached to the frame (710-2); and A plurality of bolts (720-5, 720-6, 720-7, 720-8) are attached to the side walls of the vertical opening (730-2), wherein Bolts (720-5, 720-6, 720-7, 720-8) are capable of engaging corresponding recesses in the cylindrical surfaces of a plurality of cylinders (741-1, 741-2, 741-3, 741-4) of the load (740) to secure the load (740), wherein the cylinders (741-1, 741-2, 741-3, 741-4) of the load (740) are capable of being rotated by the bolts (720-5, 720-6, 720-7, 720-8) by applying a force along the cylinder axis.

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