Foldable unmanned aerial vehicle and control method thereof

Abstract

The invention relates to the technical field of flight equipment, in particular to a foldable unmanned aerial vehicle and a control method thereof.The foldable unmanned aerial vehicle comprises a first middle wing and a second middle wing which are arranged in parallel and connected through a double-wing connecting module; the two first folding wings are arranged at the two ends of the first middle wing respectively, and the two first folding wings are symmetrically arranged; the two second folding wings are arranged at the two ends of the second middle wing respectively, and the two second folding wings are symmetrically arranged; when the foldable unmanned aerial vehicle takes off and lands, the first folding wing is in a state of being folded towards the second middle wing, the second folding wing is in a state of being folded towards the first middle wing, and after the foldable unmanned aerial vehicle rotates to fly horizontally, the first folding wing is unfolded towards the direction away from the second middle wing, and the second folding wing is unfolded towards the direction away from the first middle wing. The occupied area of the foldable unmanned aerial vehicle in the take-off and landing stage is at least reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of flying equipment, and in particular relates to a foldable unmanned aerial vehicle and a control method thereof. Background Art

[0002] With the continuous development of drones and technology, the application of drones in various fields is accelerating. Among them, the demand for drones that can achieve vertical take-off and landing and have long flight time is increasing. Faced with the continuous development of various new scenarios, the working conditions in specific environments have also put forward new requirements for drones, especially in taking off and landing in small areas, and taking off with vehicle-mounted drones. It is required that drones can operate in a smaller take-off and landing environment while ensuring their working ability. This requirement is difficult to achieve technically and its stability is difficult to guarantee. Solving this problem can further promote the special application of drones and has long-term significance for promoting the development of the low-altitude drone field.

[0003] Patent application publication number CN116573180A and patent application publication number CN117550116A both provide a UAV with foldable wings. Specifically, the wings are folded or flipped through a driving mechanism. However, such structures are static folding and are only used to improve the problem of excessive storage space occupied by the UAV. As for solving the problem of floor space occupied during storage and transportation of the UAV, it is more effective to adopt a disassembly and assembly method without adding too much weight. The structure provided by the above patents cannot achieve folding changes during flight, has a small adaptability, and cannot be used in situations with a small take-off and landing area.

[0004] Therefore, in the prior art, most of the folding functions of the wings are only manually folded to solve the problem of reducing the space occupied when stored on the ground, and the folding function cannot be realized during flight. Some technologies that realize folding during flight also have low stability before and after folding. Summary of the invention

[0005] In view of this, the present invention aims to provide a foldable UAV and a control method thereof, which at least helps to reduce the floor space occupied by the foldable UAV during take-off and landing.

[0006] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0007] The invention provides a foldable drone, comprising: a first middle wing and a second middle wing arranged in parallel, the first middle wing and the second middle wing being connected by a double-wing connection module; two first folding wings, the two first folding wings being respectively arranged at two ends of the first middle wing, and the two first folding wings being symmetrically arranged; two second folding wings, the two second folding wings being respectively arranged at two ends of the second middle wing, and the two second folding wings being symmetrically arranged; when the foldable drone takes off and lands, the first folding wing is in a state of being folded toward the second middle wing, and the second folding wing is in a state of being folded toward the first middle wing, and after the foldable drone turns to level flight, the first folding wing is unfolded in a direction away from the second middle wing, and the second folding wing is unfolded in a direction away from the first middle wing.

[0008] Furthermore, the first folding wing includes a first outer wing and a first small wing connected in sequence along a direction away from the first middle wing, the first outer wing is folded not more than 90° relative to the first middle wing by a first outer wing folding mechanism, and the first small wing is folded not more than 180° relative to the first outer wing by a first small wing folding mechanism; the second folding wing includes a second outer wing and a second small wing connected in sequence along a direction away from the second middle wing, the second outer wing is folded not more than 90° relative to the second middle wing by a second outer wing folding mechanism, and the second small wing is folded not more than 180° relative to the second outer wing by a second small wing folding mechanism.

[0009] Furthermore, the distance between the first middle wing and the second middle wing is greater than the length of the first outer wing and less than twice the length of the first outer wing; the distance between the first middle wing and the second middle wing is greater than the length of the second outer wing and less than twice the length of the second outer wing; the distance between the first middle wing and the second middle wing is greater than the sum of the length of the first small wing and the length of the second small wing.

[0010] Furthermore, when the first folding wing is folded toward the direction of the second middle wing, the first folding wing is folded 90° relative to the first middle wing along the first rotation axis; when the second folding wing is folded toward the direction of the first middle wing, the second folding wing is folded 90° relative to the second middle wing along the second rotation axis; while the first folding wing is folded, it moves toward the nose along the extension direction of the first rotation axis, and while the second folding wing is folded, it moves along the extension direction of the second rotation axis, so that the longitudinal stability margin of the foldable drone remains unchanged before and after the first folding wing and the second folding wing are folded.

[0011] Furthermore, the structure of the first outer wing folding mechanism is the same as that of the second outer wing folding mechanism; the first outer wing folding mechanism includes a driving module, a rotating module and a limiting module; wherein the driving module includes a first driving output unit, a first transmission shaft and a transmission tooth connected to each other, the first driving output unit drives the first transmission shaft to rotate, and then drives the transmission tooth to rotate; the rotating module includes a transmission sleeve, the inner ring of the transmission sleeve is provided with a tooth groove, the tooth groove cooperates with the transmission tooth to rotate under the drive of the driving module, and a slider is provided on the transmission sleeve, one end of the slider is connected to the transmission sleeve, and the other end of the slider is fixedly connected to the first outer wing; the limiting module is in the form of a sleeve, and the limiting module is provided with a spiral sliding groove, and when the rotating module rotates, the slider slides along the spiral sliding groove.

[0012] Furthermore, the structure of the first winglet folding mechanism is the same as that of the second winglet folding mechanism; the first winglet folding mechanism includes a second drive output unit, a second transmission shaft, a fixed gear, a rotating gear and a connecting plate, the second drive output unit is coaxially connected to the second transmission shaft, one end of the connecting plate is fixedly connected to the second transmission shaft, the other end of the connecting plate is fixedly connected to the rotating gear through a pressing cap, the fixed gear is fixedly connected to the first outer wing, the rotating gear is fixedly connected to the first winglet, and the second drive output unit drives the second transmission shaft and the connecting plate to rotate so that the rotating gear rotates along the fixed gear.

[0013] Furthermore, when the first folding wing and the second folding wing are folded, one of the first folding wing and the second folding wing is folded first. When the second folding wing is folded first, the second outer wing is folded 90° toward the first middle wing, the second small wing is folded 180° away from the first middle wing, the first small wing is folded 180° toward the second middle wing, and the first outer wing is folded 90° toward the second middle wing.

[0014] Furthermore, a clamping structure is provided on the first outer wing and the second outer wing, and a roller block cooperating with the clamping structure is provided on the first winglet and the second winglet. When the first folding wing and the second folding wing are in a folded state, the roller block on the first winglet is engaged in the clamping structure of the second outer wing, and the roller block on the second winglet is engaged in the clamping structure of the first outer wing.

[0015] Furthermore, the foldable drone also includes a power system, which is arranged on the first outer wing and the second outer wing. The power system arranged on the first outer wing is adjacent to the first winglet folding mechanism, and the power system arranged on the second outer wing is adjacent to the second winglet folding mechanism.

[0016] Another aspect of the present invention provides a control method for a foldable drone, comprising: providing the above-mentioned foldable drone; when the foldable drone stands on the ground in a vertical mode, the first folding wing and the second folding wing are in a folded state, and the direction in which the first middle wing and the second middle wing point is a horizontal direction; the foldable drone takes off in a vertical mode, and after takeoff, the foldable drone accelerates and switches to a level flight mode, and when the foldable drone is in the level flight mode, the angle between the direction in which the first middle wing points to the second middle wing and the vertical direction is less than the stall angle of attack; after the foldable drone enters the level flight mode, the first folding wing and the second folding wing are unfolded, the flight speed of the foldable drone is reduced, and the foldable drone enters a cruising mode; when the foldable drone lands, the first folding wing and the second folding wing are flipped from an unfolded state to a folded state, the foldable drone increases its flight speed, switches to a vertical mode, and then descends to the ground.

[0017] Compared with the prior art, the invention can achieve the following beneficial effects:

[0018] In view of the problems existing in the prior art, an embodiment of the present invention provides a foldable UAV, which is beneficial to significantly reduce the floor space occupied by the UAV during the take-off and landing stages. In this way, on the one hand, the UAV can be suitable for take-off and landing in narrow areas, for example, it is suitable for vehicle-mounted take-off applications. On the other hand, the convenience of daily storage of the UAV is improved. It occupies a small space and does not require disassembly and assembly, which is beneficial to reduce the electrical plug-in and the like generated during the disassembly and assembly process, and is convenient to use. The folding function can increase the flexibility of UAV application. During flight, the outer wings can be used as winglets at the wingtips. During level flight, the outer wings can be flipped up to improve aerodynamic performance. During vertical wind resistance, the outer wings can be flipped down to reduce airflow disturbances and thus enhance wind resistance. In addition, the folded state is adopted in the take-off and landing mode, which can significantly reduce the windward area and further improve the wind resistance. At the same time, the folded wings can play a rigid support role after being retracted, which is beneficial to improving the stability of the foldable UAV. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0020] Figure 1 This is a schematic diagram of the structure of the foldable drone in the unfolded state according to an embodiment of the present invention;

[0021] Figure 2 A schematic diagram of the structure of the foldable drone in a folded state according to an embodiment of the present invention;

[0022] Figure 3 A schematic diagram of the structure of the first outer wing folding mechanism according to an embodiment of the present invention;

[0023] Figure 4 A schematic diagram of the structure of the first winglet folding mechanism according to an embodiment of the present invention;

[0024] Figure 5 A schematic diagram of the structure of the first winglet folding mechanism connected to the first winglet and the first outer wing according to an embodiment of the present invention;

[0025] Figure 6 A schematic diagram of the folding process of the foldable drone according to an embodiment of the present invention;

[0026] Figure 7 A schematic diagram of the structure of the first folding wing and the second folding wing in a folded state according to an embodiment of the present invention;

[0027] Figure 8 A schematic diagram of the structure of the clamping structure and the rolling block described in the embodiment of the present invention;

[0028] Fig. 9 A schematic diagram of the posture of the foldable drone during take-off, landing and flight according to an embodiment of the present invention;

[0029] Fig.10 Schematic diagrams of two postures of the foldable drone described in the embodiment of the present invention.

[0030] Explanation of the reference numerals: 11. first middle wing; 21. second middle wing; 12. first outer wing; 13. first small wing; 22. second outer wing; 23. second small wing; 14. first outer wing folding mechanism; 15. first small wing folding mechanism; 24. second outer wing folding mechanism; 25. second small wing folding mechanism; 3. double-wing connection module. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0032] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0033] In the description of the invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, the meaning of "multiple" is two or more.

[0034] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0035] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0036] The present invention provides a foldable drone. Figure 1 and Figure 2 , including: a first middle wing 11 and a second middle wing 21 arranged in parallel, the first middle wing 11 and the second middle wing 21 are connected by a double-wing connection module 3; two first folding wings, the two first folding wings are respectively arranged at both ends of the first middle wing 11, and the two first folding wings are symmetrically arranged; two second folding wings, the two second folding wings are respectively arranged at both ends of the second middle wing 21, and the two second folding wings are symmetrically arranged; when the foldable UAV takes off and lands, the first folding wing is in a state of folding in the direction of the second middle wing 21, and the second folding wing is in a state of folding in the direction of the first middle wing 11. After the foldable UAV turns to level flight, the first folding wing is unfolded in a direction away from the second middle wing 21, and the second folding wing is unfolded in a direction away from the first middle wing 11.

[0037] During the take-off and landing process of the foldable UAV provided by the invention, the first folding wing and the second folding wing are in a folded state. After the foldable UAV turns to level flight, the first folding wing and the second folding wing are unfolded, so that the wings can perform cruising flight in a fully unfolded state. In this way, the floor space occupied during the take-off and landing stages can be greatly reduced, and the wingspan is increased during level flight, which is conducive to improving the lift force for level flight.

[0038] In some embodiments, the first folding wing includes a section of foldable wing, and the second folding wing also includes a section of foldable wing. In other embodiments, the first folding wing may include two sections of foldable wings. Specifically, the first folding wing includes a first outer wing 12 and a first winglet 13 connected in sequence along a direction away from the first middle wing 11, and the second folding wing also includes two sections of foldable wings. Specifically, the second folding wing includes a second outer wing 22 and a second winglet 23 connected in sequence along a direction away from the second middle wing 21.

[0039] In some embodiments, the first folding wing includes a first outer wing 12 and a first winglet 13 connected in sequence along a direction away from the first middle wing 11, the first outer wing 12 is folded not more than 90° relative to the first middle wing 11 through a first outer wing folding mechanism 14, and the first winglet 13 is folded not more than 180° relative to the first outer wing 12 through a first winglet folding mechanism 15; the second folding wing includes a second outer wing 22 and a second winglet 23 connected in sequence along a direction away from the second middle wing 21, the second outer wing 22 is folded not more than 90° relative to the second middle wing 21 through a second outer wing folding mechanism 24, and the second winglet 23 is folded not more than 180° relative to the second outer wing 22 through a second winglet folding mechanism 25.

[0040] It can be understood that when the first folding wing includes a section of foldable wing and the second folding wing also includes a section of foldable wing, only the folding mechanism is provided between the first middle wing 11 and the first folding wing and between the second middle wing 21 and the second folding wing.

[0041] When the first folding wing includes a first outer wing 12 and a first winglet 13 connected in sequence along a direction away from the first middle wing 11, and the second folding wing includes a second outer wing 22 and a second winglet 23 connected in sequence along a direction away from the second middle wing 21, it not only improves the flexibility of use of the foldable drone, but also avoids overly complicated mechanisms, and at the same time can achieve a larger level flight wingspan with a smaller footprint.

[0042] Specifically, refer to Figure 1 and Figure 2 , Figure 1 The first folding wing and the second folding wing are both in a folded state. Figure 2 The first folding wing and the second folding wing are both in the unfolded state.

[0043] In some embodiments, the distance between the first middle wing 11 and the second middle wing 21 is greater than the length of the first outer wing 12 and less than twice the length of the first outer wing 12; the distance between the first middle wing 11 and the second middle wing 21 is greater than the length of the second outer wing 22 and less than twice the length of the second outer wing 22; the distance between the first middle wing 11 and the second middle wing 21 is greater than the sum of the length of the first small wing 13 and the length of the second small wing 23.

[0044] That is to say, the distance between the first middle wing 11 and the second middle wing 21 is greater than and close to the length of the first outer wing 12, and greater than and close to the length of the second outer wing 22. At the same time, the distance between the first middle wing 11 and the second middle wing 21 is greater than and close to the sum of the length of the first small wing 13 and the length of the second small wing 23. The reason for such arrangement is to avoid the first middle wing 11 and the second middle wing 21 from interfering with the folding of the first folding wing and the second folding wing.

[0045] In some embodiments, a propeller is disposed at each end of the first middle wing, a propeller is disposed at each end of the second middle wing, and a propeller is also disposed on each first outer wing and each second outer wing.

[0046] In some embodiments, the distance between the first middle wing 11 and the second middle wing 21 may be between 1 and 3 times the equivalent aerodynamic chord length of the UAV. Since after the first folding wing and the second folding wing are folded, the propeller on the first outer wing 12 is close to the second middle wing 21, and the propeller on the second outer wing 22 is close to the first middle wing 11, the distance between the first middle wing 11 and the second middle wing 21 needs to be sufficient to avoid the propellers on the first outer wing 12 and the second outer wing 22 from striking.

[0047] In summary, the size of each part of the wing can be determined according to the relationship between the length of the first outer wing 12, the length of the second outer wing 22, the length of the first winglet 13, and the length of the second winglet 23 and the distance between the first middle wing 11 and the second middle wing 21, the relationship between the distance between the first middle wing 11 and the second middle wing 21 and the multiple of the equivalent aerodynamic chord length, the influence of the propeller after folding, and the size index requirements after folding.

[0048] It should be noted that when the foldable UAV is in a folded state and flying level, if its aerodynamic center position is defined as NP1, and when the foldable UAV is in an unfolded state and flying level, its aerodynamic center position is defined as NP2, it can be understood that in the folded state, the wingspan is small, and the aerodynamic center position NP1 is forward relative to the nose. In the unfolded state, the wingspan is large, and the aerodynamic center position NP2 is backward relative to the nose. If only the wingspan changes, the aerodynamic center position will change. If the center of gravity of the whole machine does not move accordingly, when the wingspan is shortened, the aerodynamic center position moves, the longitudinal stability cannot be well guaranteed, and the safety performance of the aircraft is reduced. In view of the above problems, the foldable UAV provided in an embodiment of the present invention needs to move the center of gravity of the whole machine accordingly by Lcg when the two states are converted. Lcg≈NP2-NP1. Since only the folding of the folding wings occurs during the folding process, the center of gravity needs to move accordingly during the folding of the folding wings to ensure that the longitudinal stability margin remains almost unchanged.

[0049] Specifically, in some embodiments, when the first folding wing is folded toward the second middle wing 21, the first folding wing is folded 90° along the first rotation axis relative to the first middle wing 11; when the second folding wing is folded toward the first middle wing 11, the second folding wing is folded 90° along the second rotation axis relative to the second middle wing 21; while the first folding wing is folded, it moves toward the nose along the extension direction of the first rotation axis, and while the second folding wing is folded, it moves along the extension direction of the second rotation axis, so that the longitudinal stability margin of the foldable drone remains unchanged before and after the first folding wing and the second folding wing are folded.

[0050] In some embodiments, the first middle wing 11 and the second middle wing 21 are both provided with a certain sweep angle. If there is no sweep angle, a module such as a horizontal tail is required to balance the whole machine. When the first middle wing 11 and the second middle wing 21 are both provided with a sweep angle, and the folding line of the folding wing is parallel to the longitudinal axis, if only the folding wing is flipped and folded, the center of gravity of the whole machine does not change. The embodiment of the present invention moves the folding wing longitudinally toward the nose direction while flipping, so that the center of gravity can be moved simultaneously during the folding process. When a sweep angle is provided, and the folding line of the folding wing is at a certain angle to the longitudinal axis, when the folding wing is folded, there may be a direct change in the displacement of the center of gravity. At this time, it is still necessary to ensure that the center of gravity moves forward, but after the angle is folded, the propeller is at a certain angle to the longitudinal axis of the whole machine, and the propeller motor has other directional components. It is necessary to ensure that the vertical component is sufficient to meet the take-off weight of the foldable drone.

[0051] In some embodiments, the first outer wing folding mechanism 14 and the second outer wing folding mechanism 24 have the same structure; Figure 3The first outer wing folding mechanism 14 includes a driving module 141, a rotating module 142 and a limiting module 143; wherein the driving module 141 includes a first driving output unit 1411, a first transmission shaft 1412 and a transmission gear 1413 connected to each other, the first driving output unit 1411 drives the first transmission shaft 1412 to rotate, and then drives the transmission gear 1413 to rotate; the rotating module 142 includes a transmission sleeve 1421, the inner ring of the transmission sleeve 1421 is provided with a tooth groove, and the tooth groove is connected to the transmission gear 1413. The teeth 1413 cooperate to rotate under the drive of the driving module. The transmission sleeve 1421 is provided with a slider 1422. One end of the slider 1422 is connected to the transmission sleeve 1421, and the other end of the slider 1422 is fixedly connected to the first outer wing 12. The limiting module 143 is in the form of a sleeve. The limiting module 143 is fixed to the first middle wing 11. The limiting module 143 is provided with a spiral sliding groove 1431. When the rotating module 142 rotates, the slider 1422 slides along the spiral sliding groove 1431. Among them, the driving module is used to provide a rotation output force. Under the drive of the driving module, the rotating module 142 rotates, and under the limiting condition of the limiting module 143, the rotating module 142 realizes axial movement while rotating.

[0052] In some examples, the first drive output unit 1411 may be a mechanism such as a motor or a servo that can provide a rotation output, and the number of the transmission teeth 1413 may be several to ensure uniform force transmission.

[0053] In some embodiments, the transmission sleeve 1421 may be provided with a ball 1423, which may be embedded in the transmission sleeve 1421 during processing; in other embodiments, a micro ball bushing may be added to the transmission sleeve 1421 to achieve sliding between the rotation module 142 and the limit module 143. Other sliding surfaces may use lubricants or a form similar to balls to reduce friction, which will not be described in detail here.

[0054] In the above embodiment, the driving module provides rotational drive for the rotation module 142, the limiting module 143 provides axial displacement guidance for the rotation module 142, and the slider 1422 on the rotation module 142 is connected to the first outer wing, so that the first outer wing can achieve rotation and axial movement at the same time under the drive of the first winglet folding mechanism.

[0055] It can be understood that the rotation angle of the slider 1422 from the starting point to the end point of the spiral sliding groove 1431 is 90°, and the length from the starting point to the end point of the spiral sliding groove 1431 along the axial direction is the axial movement distance of the first outer wing. The moving distance needs to ensure that the center of gravity of the whole machine produces the movement of Lcg.

[0056] In some embodiments, the first winglet folding mechanism 15 and the second winglet folding mechanism 25 have the same structure; Figure 4The first winglet folding mechanism 15 includes a second drive output unit 151, a second transmission shaft 152, a fixed gear 153, a rotating gear 154 and a connecting plate 155. The second drive output unit 151 is coaxially connected to the second transmission shaft 152, one end of the connecting plate 155 is fixedly connected to the second transmission shaft 152, and the other end of the connecting plate 155 is fixedly connected to the rotating gear 154 through a pressing cap. The fixed gear 153 is fixedly connected to the first outer wing 12, and the rotating gear 154 is fixedly connected to the first winglet 13. The second drive output unit 151 drives the second transmission shaft 152 and the connecting plate 155 to rotate, so that the rotating gear 154 rotates along the fixed gear 153.

[0057] The second drive output unit 151 can be a mechanism that can provide rotation output, such as a motor or a steering gear. During the rotation process, the second drive output unit 151 can drive the first winglet 13 to achieve 180° folding relative to the first outer wing 12; specifically, the lower surface of the first outer wing 12 away from the nose is relatively flat, so the first winglet 13 can rotate toward the lower surface to complete the folding, such as Figure 5 As shown, it is understandable that, when there is a special need, the first winglet 13 can also be folded toward the upper surface of the first outer wing 12. At this time, it is necessary to ensure that the folded first winglet 13 does not interfere with other structures.

[0058] In some embodiments, when the first folding wing and the second folding wing are folded, one of the first folding wing and the second folding wing is folded first. When the second folding wing is folded first, the second outer wing 22 is folded 90° toward the first middle wing 11, the second small wing 23 is folded 180° away from the first middle wing 11, the first small wing 13 is folded 180° toward the second middle wing 21, and the first outer wing 12 is folded 90° toward the second middle wing 21.

[0059] Specifically, refer to Figure 6 When folding, the second folding wing is folded first. When the movement stroke of the second folding wing has passed the interference area with the movement stroke of the first folding wing, the first folding wing begins to fold. The folding direction is as follows Figure 6 As shown in (a), refer to Figure 6 In (b), the middle wing folding mechanism and the outer wing folding mechanism can rotate synchronously. When the middle wing is flipped to a predetermined position, the outer wing is folded synchronously, thereby reducing the time consumed in the folding process. Figure 6As shown in (c), the foldable UAV is a frame-shaped structure when viewed from the nose direction, which effectively reduces the floor space. Compared with the traditional composite wing UAV, under the same load and flight time performance indicators, the UAV with two parallel wing layout provided by the embodiment of the present invention occupies about one-third of the floor space of the traditional composite wing UAV. By adopting this folding method, the floor space in the folded state can be further made half of the area in the unfolded state, which not only enhances the adaptability to the requirements of narrow take-off and landing space, but also facilitates the storage of the foldable UAV without disassembly and assembly, which is more convenient.

[0060] In some examples, the foldable drone provided by the embodiments of the present invention has a wingspan of about 2 meters when the folded wings are in the unfolded state, and a wingspan of about 1 meter after being folded. This folded size can be fully adapted to the size of the roof, and can realize the vehicle-mounted take-off function.

[0061] It should be noted that, due to the thickness of the wing and the fit of the first folding wing and the second folding wing after folding, the total length of the first folding wing is not equal to the total length of the second folding wing when unfolded. Figure 6 In the folding method, the first folding wing is longer than the second folding wing. When folded, the second folding wing is gathered on the inner side of the first folding wing. When flying at level, the lift coefficient of the first folding wing is greater, so the longer first folding wing helps to improve the overall lift.

[0062] In some examples, the second folding wing may be set longer, and the first folding wing may be folded inside the second folding wing when folding.

[0063] In some embodiments, reference Figure 7 The first outer wing 12 and the second outer wing 22 are both provided with a clamping structure 122, and the first winglet 13 and the second winglet 23 are both provided with a roller 231 that cooperates with the clamping structure 122. When the first folding wing and the second folding wing are in the folded state, the roller 231 on the first winglet 13 is engaged with the clamping structure 122 of the second outer wing 22, and the roller 231 on the second winglet 23 is engaged with the clamping structure 122 of the first outer wing 12. After folding, the clamping structure 122 and the roller 231 are automatically clamped, thereby improving the stability of the whole structure in the folded state. Since the foldable drone provided by the embodiment of the present invention adopts a distributed power system, it may be more likely to vibrate in the vertical take-off mode. After adopting the folding method, the wingspan can be reduced, and the propeller position can be concentrated. At the same time, the folded folding wings can be fixed by the clamping structure 122 and the roller 231, which can play a role of rigid stability at the same time, thereby increasing the overall stability of the drone and helping to reduce vibration problems.

[0064] In some embodiments, one or more sets of corresponding clamping structures 122 and rolling blocks 231 may be provided on each corresponding outer wing and middle wing.

[0065] In some embodiments, reference Figure 8 The clamping structure 122 is provided with a matching block 1221, a spring 1222 and a stop block 1223. When the rolling block 231 is clamped into the clamping structure 122, the rolling block 231 contacts the matching block 1221, and the matching block 1221 is forced to open to both ends under the guidance of the stop block 1223, and the rolling block 231 is then clamped in. After the rolling block 231 is clamped in, the matching block 1221 is reset under the thrust of the spring 1222, and the stop block 1223 is clamped. The clamping structure 122 is sunken into the skin surface of the middle wing so that there is no protrusion in the unfolded state and no additional resistance is generated. The rolling block 231 is aerodynamically guided on the windward surface, and its structure is small, which has little effect on resistance.

[0066] In some embodiments, other mechanical clamping structures or electromagnetic locking devices may be used to ensure the stability of the folding wings in the folded state. Similarly, in the unfolded state, a similar clamping structure or a rotating clamping structure may be used to limit and lock the folding mechanism.

[0067] In some embodiments, the foldable drone also includes a power system, which is arranged on the first outer wing 12 and the second outer wing 22. The power system arranged on the first outer wing 12 is adjacent to the first winglet folding mechanism 15, and the power system arranged on the second outer wing 22 is adjacent to the second winglet folding mechanism 25.

[0068] Specifically, the side view of the folded folding wing is as follows: Figure 7 As shown, a power system may be provided on the first outer wing 12 and the second outer wing 22. The power system is provided at the first motor cabin 121 and the second motor cabin 221. The power system may include a motor, an electric regulator and a propeller. The power system is close to the folding part of the outer wing. In this way, the distance between the first middle wing 11 and the second middle wing 21 can be reduced while avoiding interference between the propellers of the two power systems. At the same time, when unfolding, more aileron area can be ensured to be in the slipstream area of ​​the propeller to ensure the control performance.

[0069] In some embodiments, in addition to the power systems on the first outer wing 12 and the second outer wing 22, the foldable drone also includes several other power systems. The other power systems are symmetrically arranged in pairs, and the propellers of the power systems do not interfere with each other in the unfolded, folded and other states.

[0070] The foldable drone provided in the embodiment of the present invention can be applied to different flight modes because of its folding function, including the following flight modes:

[0071] Conventional flight mode: Reference Fig. 9The foldable drone stands vertically on the ground in a folded state. When taking off, all motors of the foldable drone are started, driving the corresponding propellers to rotate, generating a vertical upward pull. The foldable drone takes off in a vertical mode, and then accelerates to enter the conversion mode and switches to the level flight mode. After entering the level flight mode, the whole machine begins to open from the folded state to the unfolded state. After unfolding, the wingspan increases, and the flight speed can be reduced accordingly to enter the cruise mode. In the cruise mode, since the foldable drone has a multi-power distributed layout, the motors on the first and second middle wings can be turned off, and only the four or diagonal motors on the middle wing can be turned on. The two motors on the line can reduce power consumption; accordingly, when the foldable UAV lands, it flips from the unfolded state to the folded state, and due to the reduction of the wingspan, it needs to increase the flight speed to maintain lift, and then enter the conversion mode, convert to the vertical mode, and descend steadily. This method can not only reduce the footprint during takeoff and landing, but also help to improve the stability of the vertical mode. The wingspan is reduced in the vertical state, which can greatly reduce the windward area of ​​the foldable UAV, and the overall body is frame-shaped after folding, which can reduce the vortex of the airflow between the first middle wing 11 and the second middle wing 21, thereby improving the safety performance of the vertical mode.

[0072] Low power level flight mode: reference Fig.10 Since the outer wing can rotate under the drive of the outer wing folding mechanism, the first winglet 13 and the second winglet 23 can be rotated to the flipped state, and the first winglet 13 and the second winglet 23 can be used as wingtip winglets to further increase lift. At the same time, the flipped outer wing helps to suppress the development of wingtip vortices and reduce induced drag, thereby further improving the aerodynamic performance of the foldable UAV during flight; after switching from the vertical mode to the level flight, it enters the low-power level flight mode. Specifically, several limit card slots can be added to the outer wing folding mechanism for locking at a predetermined position. After locking, there is no need for the drive module to continuously consume power, thereby reducing power loss. The front view of the low-power level flight mode is as follows Fig.10 As shown in (a) in .

[0073] Hover gaze mode: Reference Fig.10 During the flight, if it is necessary to use the vertical mode to focus on a certain position using the optical load for observation, and then continue to fly horizontally after the observation, there is no need to perform the folding process before and after the conversion, and the conversion between the horizontal flight and the vertical mode can be performed in a fully unfolded state; and when focusing on the observation in the vertical mode, the first winglet 13 and the second winglet 23 are flipped to the downward state to reduce wind disturbance, such as Fig.10As shown in (b) in the figure; during the landing process, the foldable drone will use sensors to detect wind force and direction and automatically align with the wind direction. If the wind is strong, the foldable drone will not be in a completely vertical state and will have a certain pitch angle. At this time, the lower wing surface of the foldable drone is the windward surface, and the second folding wing is in a downward flipped state, which helps to reduce the impact of crosswinds and the disturbance caused by the airflow flipping from the wing tip to the inside between the wings, thereby enhancing the stability of the hovering mode. If direct landing is required at this time, it can be directly landed vertically in this posture; if the landing space is limited, it can also be folded and landed in this posture, which has high application flexibility.

[0074] Another aspect of the present invention provides a control method for a foldable drone, comprising: providing the above-mentioned foldable drone; when the foldable drone stands on the ground in a vertical mode, the first folding wing and the second folding wing are in a folded state, and the direction in which the first middle wing 11 points to the second middle wing 21 is a horizontal direction; the foldable drone takes off in a vertical mode, and after take-off, the foldable drone accelerates to switch to a level flight mode, and when the foldable drone is in the level flight mode, the angle between the direction in which the first middle wing 11 points to the second middle wing 21 and the vertical direction is less than the stall angle of attack, and in some examples, the angle between the direction in which the first middle wing 11 points to the second middle wing 21 and the vertical direction may be less than 15°; after the foldable drone enters the level flight mode, the first folding wing and the second folding wing are unfolded, the flight speed of the foldable drone is reduced, and the foldable drone enters a cruising mode; when the foldable drone lands, the first folding wing and the second folding wing are flipped from an unfolded state to a folded state, and the foldable drone increases its flight speed, switches to a vertical mode, and then descends to the ground.

[0075] The foldable UAV and the control method thereof provided by the embodiment of the present invention are conducive to reducing the floor space occupied by the foldable UAV. On the one hand, the foldable UAV can be suitable for take-off and landing in narrow areas and for vehicle-mounted take-off applications. On the other hand, the convenience of daily storage of the UAV can be improved. The space occupied is small and no disassembly and assembly operations are required, which reduces the electrical plugging and the like generated during the disassembly and assembly process, and the UAV is more user-friendly. Moreover, the realization of this folding function can increase the application flexibility of the foldable UAV. The outer wings can be used as winglets, which can be flipped up during level flight to improve aerodynamic performance; they can be flipped down during vertical wind resistance to reduce airflow disturbance and enhance wind resistance. Moreover, the folded state is adopted in the conventional vertical take-off mode, which can greatly reduce the windward area and further improve the wind resistance. At the same time, the folding wings can play a rigid support role after being retracted, reduce vibration factors, and comprehensively improve the stability of the foldable UAV.

[0076] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0077] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A foldable drone, characterized in that: include: A first middle wing and a second middle wing are arranged in parallel, wherein the first middle wing and the second middle wing are connected via a double-wing connection module; Two first folding wings, the two first folding wings are respectively arranged at two ends of the first middle wing, and the two first folding wings are symmetrically arranged; Two second folding wings, the two second folding wings are respectively arranged at two ends of the second middle wing, and the two second folding wings are symmetrically arranged; When the foldable drone takes off and lands, the first folding wing is in a state of being folded toward the second middle wing, and the second folding wing is in a state of being folded toward the first middle wing. After the foldable drone turns to level flight, the first folding wing is unfolded in a direction away from the second middle wing, and the second folding wing is unfolded in a direction away from the first middle wing.

2. The foldable drone according to claim 1, characterized in that: The first folding wing comprises a first outer wing and a first small wing connected in sequence in a direction away from the first middle wing, the first outer wing is folded by no more than 90° relative to the first middle wing by a first outer wing folding mechanism, and the first small wing is folded by no more than 180° relative to the first outer wing by a first small wing folding mechanism; The second folding wing includes a second outer wing and a second small wing connected in sequence in a direction away from the second middle wing, the second outer wing is folded not more than 90° relative to the second middle wing by a second outer wing folding mechanism, and the second small wing is folded not more than 180° relative to the second outer wing by a second small wing folding mechanism.

3. The foldable drone according to claim 2, characterized in that: The distance between the first middle wing and the second middle wing is greater than the length of the first outer wing and less than 2 times the length of the first outer wing; The distance between the first middle wing and the second middle wing is greater than the length of the second outer wing and less than 2 times the length of the second outer wing; The distance between the first middle wing and the second middle wing is greater than the sum of the length of the first small wing and the length of the second small wing.

4. The foldable drone according to claim 1, characterized in that: When the first folding wing is folded toward the second middle wing, the first folding wing is folded 90° relative to the first middle wing along the first rotation axis; When the second folding wing is folded toward the first middle wing, the second folding wing is folded 90° relative to the second middle wing along the second rotation axis; The first folding wing moves toward the nose along the extension direction of the first rotation axis while being folded, and the second folding wing moves along the extension direction of the second rotation axis while being folded, so that the longitudinal stability margin of the foldable drone remains unchanged before and after the first folding wing and the second folding wing are folded.

5. The foldable drone according to claim 2, characterized in that: The first outer wing folding mechanism has the same structure as the second outer wing folding mechanism; The first outer wing folding mechanism includes a driving module, a rotating module and a limiting module; Wherein, the driving module comprises a first driving output unit, a first transmission shaft and a transmission tooth connected to each other, and the first driving output unit drives the first transmission shaft to rotate, thereby driving the transmission tooth to rotate; The rotating module comprises a transmission sleeve, the inner ring of which is provided with a tooth groove, the tooth groove cooperates with the transmission tooth to rotate under the drive of the driving module, and the transmission sleeve is provided with a slider, one end of which is connected to the transmission sleeve, and the other end of which is fixedly connected to the first outer wing; The limiting module is in the form of a shaft sleeve, and is provided with a spiral sliding groove. When the rotating module rotates, the sliding block slides along the spiral sliding groove.

6. The foldable drone according to claim 2, characterized in that: The first winglet folding mechanism and the second winglet folding mechanism have the same structure; The first winglet folding mechanism includes a second drive output unit, a second transmission shaft, a fixed gear, a rotating gear and a connecting plate, the second drive output unit is coaxially connected to the second transmission shaft, one end of the connecting plate is fixedly connected to the second transmission shaft, the other end of the connecting plate is fixedly connected to the rotating gear through a pressing cap, the fixed gear is fixedly connected to the first outer wing, and the rotating gear is fixedly connected to the first winglet, and the second drive output unit drives the second transmission shaft and the connecting plate to rotate so that the rotating gear rotates along the fixed gear.

7. The foldable drone according to claim 2, characterized in that: When the first folding wing and the second folding wing are folded, one of the first folding wing and the second folding wing is folded first. When the second folding wing is folded first, the second outer wing is folded 90° toward the first middle wing, the second small wing is folded 180° away from the first middle wing, the first small wing is folded 180° toward the second middle wing, and the first outer wing is folded 90° toward the second middle wing.

8. The foldable drone according to claim 7, characterized in that: The first outer wing and the second outer wing are both provided with a clamping structure, and the first winglet and the second winglet are both provided with a roller block that cooperates with the clamping structure. When the first folding wing and the second folding wing are in a folded state, the roller block on the first winglet is engaged in the clamping structure of the second outer wing, and the roller block on the second winglet is engaged in the clamping structure of the first outer wing.

9. The foldable drone according to claim 2, characterized in that: The foldable drone also includes a power system, which is arranged on the first outer wing and the second outer wing. The power system arranged on the first outer wing is adjacent to the first winglet folding mechanism, and the power system arranged on the second outer wing is adjacent to the second winglet folding mechanism.

10. A foldable drone control method, characterized in that: include: Provide a foldable drone according to any one of claims 1 to 9; When the foldable drone stands on the ground in a vertical mode, the first folding wing and the second folding wing are in a folded state, and the direction in which the first middle wing points to the second middle wing is a horizontal direction; The foldable drone takes off in a vertical mode, and after taking off, the foldable drone accelerates and switches to a level flight mode. When the foldable drone is in the level flight mode, an angle between a direction in which the first mid-wing points to the second mid-wing and a vertical direction is less than a stall angle of attack; After the foldable drone enters the level flight mode, the first folding wing and the second folding wing are unfolded, and the flight speed of the foldable drone decreases, entering the cruise mode; When the foldable drone lands, the first folding wing and the second folding wing flip from an unfolded state to a folded state, and the foldable drone increases its flight speed, switches to a vertical mode, and then descends to the ground.

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