Unmanned aerial vehicle and landing method thereof

Abstract

An unmanned aerial vehicle (UAV) is disclosed. The UAV comprises a body, a propulsion unit, a controller, and at least one adjustable camera unit. In some embodiments, each adjustable camera unit comprises a camera and a gimbal on which the camera is mounted and configured to move a field of view (FOV) of the camera in at least two axes. In some embodiments, the controller is configured to continuously receive an image stream from the at least one camera, identify an oblique target in the image stream, control the propulsion unit to approach the oblique target, and simultaneously control at least one gimbal to rotate a corresponding camera such that the oblique target is continuously identified in the image stream.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of priority to Israeli Patent Application No. 289357, filed on December 23, 2021, entitled "UNMANNED AERIAL VEHICLE AND A METHOD OF LANDING SAME," the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THEINVENTION The present invention relates generally to unmanned aerial vehicles (UAVs). More specifically, the present invention relates to a method for landing an unmanned aerial vehicle. [Background technology]

[0003] The use of UAVs such as drones has increased significantly over the last decade in light of technological advances. Vertical take-off and landing (VTOL) drones are becoming popular in many sectors for a variety of applications, such as mapping, surveying, remote sensing, inspection, search and rescue applications, as well as recreational and sports filming.

[0004] Most commercial drones are equipped with Global Navigation Satellite System (GNSS) receivers, which are used to perform a Return-to-Home (RTH) procedure whenever the UAV is expected to land. In most cases, this is accomplished by flying at a constant height to a point above the launch location and then performing a vertical landing.

[0005] When landing on a dynamic platform, such as a moving car or a ship underway, a vertical landing is very difficult because the landing point is constantly moving.

[0006] Therefore, there is a need for a method for autonomous and precise landing of a UAV on a dynamic platform. Summary of the Invention

[0007] Some aspects of the invention are directed to an unmanned aerial vehicle (UAV) comprising a body, a propulsion unit, a controller, and at least one adjustable camera unit. In some embodiments, each adjustable camera unit comprises a camera and a gimbal on which the camera is mounted and configured to move a field of view (FOV) of the camera in at least two axes. In some embodiments, the controller is configured to continuously receive an image stream from the at least one camera, identify an oblique target in the image stream, control the propulsion unit to approach the oblique target, and simultaneously control at least one gimble to rotate a corresponding camera such that the oblique target is continuously identified in the image stream.

[0008] In some embodiments, identifying the tilted target during the UVA approach is such that the tilted target is located at the center of the FOV of at least one camera. In some embodiments, controlling the propulsion unit is based on an image including the tilted target located at the center of the FOV of at least one camera. In some embodiments, controlling the propulsion unit includes receiving coordinates and a tilt angle of the tilted target, receiving a temporal tilt angle of each gimbal when the tilted target is located at the center of the FOV of each camera, calculating a temporal position of the unmanned aerial vehicle based on the angle and coordinates of the tilted target and the temporal tilt angle of each gimbal, and determining temporal population parameters based on the temporal position. In some embodiments, the tilt angle is measured relative to the horizon.

[0009] In some embodiments, the controller is further configured to identify a substantially horizontal target in the image stream, control at least one gimble to rotate a corresponding camera such that both the tilted target and the substantially horizontal target are consecutively identified in the image stream, and control the propulsion unit to approach the substantially horizontal target while approaching the tilted target until the substantially horizontal target is located substantially vertically below the UVA.

[0010] In some embodiments, the propulsion unit controls approaching the substantially horizontal target until the substantially horizontal target is located at a center of an image captured when the at least one gimbal is tilted at −90° relative to the horizon. In some embodiments, controlling the propulsion unit further includes receiving coordinates of the substantially horizontal target, and calculating a time position of the unmanned aerial vehicle also based on the coordinates of the substantially horizontal target. In some embodiments, the controller is further configured to control the propulsion unit to approach the target until only tilted targets are identified in the image stream. In some embodiments, the controller is further configured to control the propulsion unit to approach the target vertically.

[0011] In some embodiments, the tilted target comprises a first ArUco marker and the substantially horizontal target comprises a second ArUco marker different from the first ArUco marker. In some embodiments, the tilt angle of the targets is between 20 degrees and 80 degrees. In some embodiments, the tilted target is located at a distance of between 0.5 m and 10 m from the substantially horizontal target.

[0012] In some embodiments, at least one gimbal is configured to rotate through an angle between -90° and +20°.

[0013] Some aspects of the present invention are directed to a method of landing an unmanned aerial vehicle (UAV), the method including continuously receiving an image stream from at least one camera mounted on a gimbal assembled to the bottom of the UVA while the UVA is hovering, identifying an oblique target in the image stream, controlling a propulsion unit of the UVA to approach the oblique target, and simultaneously controlling the gimble to rotate the camera such that the oblique target is continuously identified in the image stream.

[0014] In some embodiments, identifying the oblique target during the UVA approach is such that the oblique target is centered in the FOV of the at least one camera. In some embodiments, controlling the propulsion unit is based on an image including the oblique target centered in the FOV of the at least one camera.

[0015] In some embodiments, controlling the propulsion unit includes receiving coordinates and a tilt angle of a tilted target, receiving a temporal tilt angle of the gimbal when the tilted target is located in the center of the FOV of at least one camera, calculating a temporal position of the unmanned aerial vehicle based on the angle and coordinates of the tilted target and the temporal tilt angle of the gimbal, and determining a temporal population parameter based on the temporal position.

[0016] In some embodiments, the tilt angle is measured relative to the horizon. In some embodiments, the temporal propulsion parameters include at least two of vertical velocity, vertical acceleration, horizontal velocity, and horizontal acceleration.

[0017] In some embodiments, the method further includes identifying a substantially horizontal target in the image stream, controlling the gimbal to rotate the corresponding camera such that both the tilted target and the substantially horizontal target are continuously identified in the image stream, and controlling the propulsion unit to approach the substantially horizontal target while approaching the tilted target until the substantially horizontal target is located substantially vertically below the UVA. In some embodiments, controlling the propulsion unit to approach the substantially horizontal target is until the substantially horizontal target is located at the center of an image captured when the gimbal is tilted at -90° relative to the horizon. In some embodiments, controlling the propulsion unit further includes receiving coordinates of the substantially horizontal target and calculating a time position of the unmanned aerial vehicle based also on the coordinates of the substantially horizontal target.

[0018] In some embodiments, controlling the propulsion unit is to vertically approach the target until only the tilted target is identified in the image stream. In some embodiments, the tilted target comprises a first ArUco marker and the substantially horizontal target comprises a second ArUco marker different from the first. In some embodiments, the tilt angle is between 20 degrees and 80 degrees.

[0019] Some additional aspects of the present invention include a target system for landing an unmanned aerial vehicle (UAV), comprising: a substantially horizontal target; and an inclined target located a known distance from the substantially horizontal target and inclined at a known angle relative to a surface plane of the substantially horizontal target.

[0020] In some embodiments, the substantially horizontal target comprises a first ArUco marker and the tilted target comprises a second ArUco marker different from the first ArUco marker. In some embodiments, the tilt angle is between 20 degrees and 80 degrees. In some embodiments, the known distance is between 0.5 m and 10 m.

[0021] The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the concluding portion of this specification, however the invention, both as to its organization and method of operation, together with its objects, features, and advantages, may best be understood by reference to the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0022] [Figure 1] Figure 1A is a diagram of a UAV according to some embodiments of the present invention, and Figure 1B is a block diagram illustrating a computing device that may be included in a system for landing a UAV on a dynamic platform according to some embodiments of the present invention. [Diagram 2] 2A and 2B are diagrams of vision-based landing parameters and 2C are diagrams of targets according to some embodiments of the present invention. [Diagram 3] 3A, 3B, and 3C are diagrams of a vision-based vertical landing process according to some embodiments of the present invention. [Figure 4] 4A, 4B, 4C, and 4D are diagrams of a vision-based distance landing process according to some embodiments of the present invention. [Diagram 5] FIG. 5 is a flowchart of a method for landing a UAV according to some embodiments of the present invention. [Figure 6] 6A, 6B, 6C, 6D, 6E, and 6F are diagrams of a vision-based landing process according to some embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] It will be understood that for simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or similar elements.

[0024] Those skilled in the art will appreciate that the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The foregoing embodiments are therefore to be considered in all respects as illustrative rather than limiting of the invention described herein. The scope of the present invention is thus indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

[0025] In the following detailed description, numerous specific details are described to provide a thorough understanding of the present invention. However, it will be understood by those skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, and components have not been described in detail so as not to obscure the present invention. Some features or elements described with respect to one embodiment may be combined with features or elements described with respect to other embodiments. For clarity, descriptions of the same or similar features or elements may not be repeated.

[0026] Although embodiments of the invention are not limited in this respect, for example, descriptions utilizing terms such as "processing," "computing," "calculating," "determining," "establishing," "analyzing," "checking," etc. may refer to operation(s) and / or process(es) of a computing platform, computing system, or other electronic computing device that manipulates and / or transforms data represented as physical (e.g., electronic) quantities in a computer's registers and / or memory into other data similarly represented as physical quantities in a computer's registers and / or memory, or into other information non-transitory storage media that may store instructions for performing the operations and / or processes.

[0027] Although embodiments of the present invention are not limited in this respect, the terms "plurality" and "a plurality" as used herein may include, for example, "multiple" or "two or more." The terms "plurality" or "a plurality" may be used throughout this specification to describe two or more components, devices, elements, units, parameters, etc. As used herein, the term "set" may include one or more items.

[0028] Unless expressly stated, the method embodiments described herein are not constrained to a particular order or sequence. Furthermore, some of the described method embodiments, or elements thereof, may occur or be performed simultaneously, contemporaneously, or in parallel.

[0029] The present invention discloses a system and method for landing a UAV on a dynamic platform. The system may perform a vision-based landing process assisted by two targets, a substantially horizontal target and an inclined target. Each target may include a different detectable marker, e.g., a different ArUco marker.

[0030] Reference is now made to FIG. 1A, which is a diagram of a UAV 100 according to some embodiments of the present invention. In some embodiments, the UAV 100 may include a body 20, a propulsion unit 30, and a computing device 10 with a controller 2, as illustrated and described with respect to FIG. 1B. In some embodiments, the UAV 100 may be a VTOL drone, as illustrated, and the body 20 and the propulsion unit 30 may include any suitable components of a VTOL drone known in the art. For example, the propulsion unit 30 may include a quad rotor (e.g., four propulsion rotors), as illustrated. The quad rotor allows for easy control of the yaw, roll, pitch, and throttle motions of the UAV 100. As used herein, yaw motion is the ability of the UAV to rotate, roll motion is the ability of the UAV to move left to right and backward, pitch motion is the ability of the UAV to move backward and forward, and throttle motion is the ability of the UAV to change its altitude.

[0031] The UAV 100 may further include at least one adjustable camera unit 40. In some embodiments, each camera unit 40 may include a camera and a gimbal on which the camera is mounted, configured to move the camera's field of view (FOV) in at least two axes (e.g., in three or four axes). The camera may be any optical camera configured to capture an image stream. The gimble may have the ability to move in at least one axis, for example, the gimble may provide pitch and / or yaw movement for the camera with a tilt angle of -90° to +20°.

[0032] In some embodiments, the UAV 100 may further include a positioning sensor, such as a GPS, an optical flow sensor, or any other additional sensor.

[0033] Reference is now made to Figure 1B, which is a block diagram illustrating a computing device that may be included within one embodiment of a controller of a UAV 100, according to some embodiments. The computing device 10 may be included / assembled within the body 20, or may remotely control the propulsion unit 30 by communicating with a communication unit included in the UAV 100.

[0034] Computing device 10 may include a processor or controller 2, which may be, for example, a central processing unit (CPU) processor, chip, or any suitable computing or computational device, an operating system 3, memory 4, executable code 5, a storage system 6, input devices 7, and output devices 8. The processor 2 (or one or more controllers or processors, possibly across multiple units or devices) may be configured to perform the methods described herein and / or to execute or function as various modules, units, etc.

[0035] Operating system 3 may be or include any code segment (e.g., similar to executable code 5 described herein) designed and / or configured to perform tasks including coordinating, scheduling, arbitrating, supervising, controlling, or otherwise managing the operation of computing device 10, such as, for example, scheduling the execution of software programs or tasks and enabling software programs or other modules or units to communicate. Operating system 3 may be a commercial operating system. It should be noted that operating system 3 may be an optional component, e.g., in some embodiments, a system may include a computing device that does not require or include an operating system 3.

[0036] The memory 4 may be or include, for example, a random access memory (RAM), a read only memory (ROM), a dynamic RAM (DRAM), a synchronous DRAM (SD-RAM), a double data rate (DDR) memory chip, a flash memory, a volatile memory, a non-volatile memory, a cache memory, a buffer, a short-term memory unit, a long-term memory unit, or other suitable memory or storage unit. The memory 4 may be or include multiple, possibly different, memory units. The memory 4 may be a non-transitory computer or processor readable medium, or a computer non-transitory storage medium, for example, a RAM. In one embodiment, the non-transitory storage medium, such as the memory 4, a hard disk drive, or another storage device, may store instructions or code that, when executed by the processor, may cause the processor to perform a method as described herein.

[0037] Executable code 5 may be any executable code, such as an application, a program, a process, a task, or a script. Executable code 5 may be executed by processor or controller 2, possibly under control of operating system 3. For example, executable code 5 may be an application that may control UAV landing as described further herein. Although a single executable code 5 is shown in FIG. 1B for clarity, systems according to some embodiments of the present invention may include multiple executable code segments similar to executable code 5 that may be loaded into memory 4 and cause processor 2 to perform methods described herein.

[0038] Storage system 6 may be or may include, for example, a flash memory known in the art, a memory within or embedded in a microcontroller or chip known in the art, a hard disk drive, a CD recordable (CD-R) drive, a Blu-ray Disc (BD), a Universal Serial Bus (USB) device, or other suitable removable and / or non-removable storage unit. Target related data, UAV data and parameters, etc. may be stored in storage system 6 or may be loaded from storage system 6 into memory 4 where they may be processed by processor or controller 2. In some embodiments, some of the components shown in FIG. 1B may be omitted. For example, memory 4 may be a non-volatile memory having the storage capacity of storage system 6. Thus, although shown as a separate component, storage system 6 may be embedded in or included in memory 4.

[0039] Input device(s) 7 may be or include any suitable input device, component, or system, such as a detachable keyboard or keypad, a mouse, etc. Output device(s) 8 may include one or more (possibly detachable) displays or monitors, speakers, and / or any other suitable output device. Any applicable input / output (I / O) devices may be connected to computing device 1 as indicated by blocks 7 and 8. For example, input device(s) 7 and / or output device(s) 8 may include a wired or wireless network interface card (NIC), a universal serial bus (USB) device, or an external hard drive. It will be appreciated that any suitable number of input devices 7 and output devices 8 may be operatively connected to computing device 1 as indicated by blocks 7 and 8.

[0040] Systems according to some embodiments of the present invention may include components such as, but not limited to, multiple central processing units (CPUs) or any other suitable general-purpose or specific processors or controllers (e.g., similar to element 2), multiple input units, multiple output units, multiple memory units, and multiple storage units.

[0041] In some embodiments, the controller 2 of the computing device 10 may be configured to control the propulsion unit 30 to land the UAV 100 using a vision-based landing procedure. A vision-based landing procedure is an autonomous lending process based on visual detection of targets, e.g., targets with ArUco markers. The ArUco markers are square fiducial markers in binary format that can be used for camera pose estimation. Diagrams of the ArUco markers on the targets are shown in Figures 2C, 3B, 6B, and 6D. Placing the ArUco markers on targets located in close proximity to the landing site can help calculate vision-based landing parameters such as distance and height required in any vision-based landing process.

[0042] 2A and 2B, which are illustrations of vision-based landing parameters according to some embodiments. In some embodiments, the distance between the camera unit 40 and the target can be calculated using the following formula: (1) F = (D÷W) × P

[0043] where F is the focal length of the camera, W is the known width of the ArUco marker, P is the apparent width of the ArUco marker in pixels, and D is the distance from the camera to the target.

[0044] In some embodiments, the focal length F can be found according to a calibration process (e.g., by taking an image of an ArUco marker at a known distance D) and the same equation can be used to find the distance between the camera and the target. (2) D = (F × W) ÷ P

[0045] The rotation matrix of the UAV can be described by equation (3).

number

[0046] where α is the yaw angle, β is the pitch angle, and γ is the roll angle.

[0047] The pitch rotation of the camera gimbal is described by equation (4).

number

[0048] where θ is the gimbal tilt angle.

[0049] Therefore, the rotation matrix of the system can be given by equation (5).

number

[0050] In some embodiments, equations (4) and (5) may be used by computing device 10 to control the movement of camera unit 40 and propulsion unit 30.

[0051] Vision-Based Landing Procedure In some embodiments, as illustrated in Figures 3A, 3B, and 3C, a substantially horizontal target with an ArUco marker is placed on the landing platform in the required landing area to assist in a vision-based vertical landing procedure. In a vision-based vertical landing procedure, the gimbal may be fixed at -90°, and the UAV 100 may hover above the landing area (Figure 3A) until an image of the ArUco marker is captured by the camera (Figure 3B). When the controller 2 recognizes the ArUco marker in the image captured by the camera unit 40, the propulsion unit 30 is controlled to lower the altitude of the UAV 100 (Figure 3C) while continuing to capture images of the ArUco marker until a complete landing is achieved. The disadvantage of this method is that at a certain low altitude, the camera unit 40 can no longer capture images of the ArUco marker, and the ArUco marker may change position relative to the UAV 100 if the target is placed on a dynamic platform that may suddenly change its height or position, such as a boat on the sea.

[0052] In some embodiments, an additional vision-based landing process known as a vision-based distance landing process can be used for autonomous landing. In the vision-based distance landing process, an additional vertical target with an ArUco marker is placed on a vertical wall at a known distance from the landing area. This process of the vision-based distance landing process is illustrated in FIG. 4A, FIG. 4B, FIG. 4C, and FIG. 4D. In some embodiments, the gimbal of the camera unit 40 may be fixed at −45°, and the UAV 100 may fly toward the landing area until two images of both the horizontal and vertical ArUco markers are captured by the camera (FIG. 4A). In a next step, the controller 2 may control the propulsion unit 30 to decrease the distance between the UAV 100 and the vertical ArUco marker target (FIG. 4B) until the horizontal ArUco marker is located substantially directly below the hovering UAV 100 (FIG. 4C). In some embodiments, the controller 2 then controls the propulsion unit 30 to lower the altitude of the UAV 100 (FIG. 4D) while continuing to capture images of the ArUco markers until a complete landing is achieved. The visual-based distance landing process has the same disadvantages as the visual-based vertical landing process.

[0053] Therefore, there is a need for a more reliable autonomous, vision-based landing process for landing UAVs on dynamic platforms, such as boats at sea or moving land vehicles.

[0054] In such a method, as illustrated in FIG. 6A and described with respect to the flow chart of FIG. 5, additional ArUco markers are placed on the tilted target.

[0055] Reference is now made to Figure 5, which is a flowchart of a method for landing an unmanned aerial vehicle (e.g., UAV 100) according to some embodiments of the present invention. The method of Figure 5 may be performed by a controller, such as controller 2 included in computing device 10, or by any other suitable controller.

[0056] In step 510, when the UVA is hovering, an image stream may be continuously received from at least one camera mounted on a gimbal assembled at the bottom of the UVA. For example, the controller 2 may receive an image stream from a camera of the camera unit 40 when the UAV 100 is approaching the landing position. The UAV 100 may be controlled to approach the landing position based on a signal received from a positioning sensor such as a GPS sensor. In some embodiments, two targets may be placed at the landing position: a substantially horizontal target 62 with a first ArUco marker, such as the ArUco marker illustrated in FIG. 6B, and an inclined target 64 with a second ArUco marker, such as the ArUco marker illustrated in FIG. 6D.

[0057] In step 520, the tilted target may be identified in the image stream. For example, the controller 2 may identify the second ArUco marker shown in FIG. 2D on the tilted target 64. In some embodiments, the controller may first identify the first ArUco marker illustrated in FIG. 6B, as described above with respect to the vision-based vertical landing process. In some embodiments, identifying the tilted target 64 during UVA approach is such that the tilted target is located in the center of the FOV of at least one camera.

[0058] In step 530, the propulsion unit 20 of the UVA 100 is controlled to approach the tilted target.

[0059] In step 540, at least one gimbal of at least one camera unit 40 is simultaneously controlled to rotate the camera such that the tilted target 64 is continuously identified in the image stream, as illustrated in Figures 6C, 6D, and 6C. In some embodiments, at a predetermined distance from the tilted target, the propulsion unit 20 of the UVA 100 may be controlled to lower the latitude of the UAV 100. The lowering of latitude may be performed while simultaneously controlling the gimbal to tilt the camera such that the ArUco markers on the tilted target 64 are continuously identified in the image stream.

[0060] In some embodiments, controlling the propulsion unit 30 is based on an image including a tilted target located at the center of the at least one camera's FOV. In some embodiments, controlling the propulsion unit 30 may include receiving coordinates and a tilt angle of the tilted target 64. In some embodiments, the tilt angle may be between 20 degrees and 80 degrees measured relative to the horizon. In some embodiments, controlling the propulsion unit 30 may further include receiving a temporal tilt angle of at least one gimbal when the tilted target is located at the center of the at least one camera's FOV, calculating a temporal position of the unmanned aerial vehicle based on the angle and coordinates of the tilted target and the temporal tilt angle of the at least one gimbal, and determining a temporal population parameter based on the temporal position. In some embodiments, the temporal population parameter includes at least two of a vertical velocity, a vertical acceleration, a horizontal velocity, and a horizontal acceleration, calculated, for example, using any one of Equations (1)-(6).

[0061] In some embodiments, the controller 2 may be further configured to identify a substantially horizontal target 62 (e.g., the target of FIG. 6B) in the image stream, control at least one gimbal to rotate a corresponding camera such that both the tilted target and the substantially horizontal target are continuously identified in the image stream, and control the propulsion unit 30 to approach the substantially horizontal target while approaching the tilted target 64 until the substantially horizontal target 62 is located substantially vertically below the UVA 100, as illustrated in FIG. 6F. In some embodiments, the controller 2 may control the propulsion unit 30 to approach the substantially horizontal target 62 until the substantially horizontal target is located in the center of the image captured when the gimbal is tilted at -90°. As described above with respect to FIGS. 2A-2C.

[0062] In some embodiments, controlling the propulsion unit 30 may include further receiving coordinates of the substantially horizontal target 62 and calculating a temporal position of the UAV 100 also based on the coordinates of the substantially horizontal target. In some embodiments, the controller 2 may be further configured to control the propulsion unit 30 to vertically approach the target 64 until only the oblique target 64 is identified in the image stream.

[0063] Some additional aspects of the present invention may be directed to a target system for landing an unmanned aerial vehicle (UAV), such as target system 60 illustrated in FIG. 6A. Target system 60 may include a substantially horizontal target 62 and an inclined target 64 located a known distance from the first target 62 and inclined at a known angle relative to a surface plane of target 62. In some embodiments, target 62 may include a first ArUco marker (illustrated in FIG. 6B) and second target 63 may include a second ArUco marker (illustrated in FIG. 6D) that is different from the first one.

[0064] In some embodiments, the tilt angle is between 20 degrees and 80 degrees. In some embodiments, the known distance is between 0.5m and 10m.

[0065] The above method and target system may enable an autonomous vision-based landing process for landing a UAV on a dynamic platform due to the ability of the camera unit 40 to receive images from the target system at various angles. Thus, following movement of the landing area in either a horizontal or vertical direction, the tilt angle of the camera in the camera unit 40 is changed to enable the controller 2 to follow at least the tilted target 64 in the target system 60 until a safe landing.

[0066] While certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will occur to those skilled in the art. It is therefore intended that the appended claims cover all such modifications and variations that fall within the true spirit of the invention.

[0067] Various embodiments are presented, each of which may of course include features from the other embodiments presented, and embodiments not specifically described may include various features described herein.

Claims

1. The main body; A propulsion unit; A controller; At least one adjustable camera unit, Camera, and a gimbal for mounting the camera and configured to move a field of view (FOV) of the camera in at least two axes; at least one adjustable camera unit, each comprising: An unmanned aerial vehicle (UAV) comprising: The controller: continuously receiving an image stream from the at least one camera; Identifying an oblique target within the image stream; Controlling the propulsion unit to approach the tilted target; simultaneously controlling at least one gimble to rotate a corresponding camera such that the oblique target is continuously identified in the image stream. It is configured as follows: Unmanned aerial vehicle (UAV).

2. The unmanned aerial vehicle of claim 1 , wherein identifying the tilted target during an approach of the UVA is such that the tilted target is located at the center of an FOV of at least one camera.

3. The unmanned aerial vehicle of claim 2 , wherein controlling the propulsion units is based on an image including the tilted target located at the center of the FOV of at least one camera.

4. controlling the propulsion unit receiving coordinates and a tilt angle of the tilted target; receiving a temporal tilt angle of each gimbal when the tilted target is located at a center of a FOV of each camera; Calculating a time position of the unmanned aerial vehicle based on the angle and coordinates of the tilted target and the time tilt angle of each gimbal; determining a temporal population parameter based on the temporal location; The unmanned aerial vehicle according to claim 2 or claim 3, comprising:

5. The unmanned aerial vehicle of claim 4 , wherein the tilt angle is measured relative to the horizon.

6. The controller: identifying a substantially horizontal target within the image stream; controlling at least one gimble to rotate a corresponding camera such that both the oblique target and the substantially horizontal target are successively identified in the image stream; Controlling the propulsion unit to approach the substantially horizontal target while approaching the tilted target until the substantially horizontal target is positioned in a substantially vertical direction of the UVA. The unmanned aerial vehicle according to any one of claims 1 to 5, configured as described above.

7. 7. The unmanned aerial vehicle of claim 6, wherein the propulsion unit controls the approach of the substantially horizontal target until the substantially horizontal target is located at the center of an image captured when the at least one gimbal is tilted at -90 degrees relative to the horizon.

8. controlling the propulsion unit further receiving coordinates of the substantially horizontal target; calculating the time position of the unmanned aerial vehicle is also based on the coordinates of the substantially horizontal target; The unmanned aerial vehicle according to claim 6 or claim 7, comprising:

9. The unmanned aerial vehicle of claim 7 or claim 8, wherein the controller is further configured to control the propulsion unit to approach the target until only the oblique target is identified in the image stream.

10. The unmanned aerial vehicle of claim 9 , wherein the controller is further configured to control the propulsion unit to vertically approach the target.

11. 11. The unmanned aerial vehicle of claim 6, wherein the inclined target comprises a first ArUco marker and the substantially horizontal target comprises a second ArUco marker different from the first ArUco marker.

12. An unmanned aerial vehicle as described in any one of claims 2 to 11, wherein the inclination angle of the target is between 20 degrees and 80 degrees.

13. An unmanned aerial vehicle according to any one of claims 6 to 12, wherein the inclined target is located at a distance of between 0.5m and 10m from the substantially horizontal target.

14. An unmanned aerial vehicle as described in any one of claims 1 to 13, wherein at least one gimbal is configured to rotate through an angle of between -90° and +20°.

15. 1. A method for landing an unmanned aerial vehicle (UAV), comprising: continuously receiving an image stream from at least one camera mounted on a gimbal assembled at the bottom of the UVA while the UVA is hovering; identifying an oblique target within the image stream; Controlling a propulsion unit of the UVA to approach the tilted target; simultaneously controlling the gimble to rotate the camera such that the oblique target is continuously identified in the image stream; A method comprising:

16. The method of claim 15 , wherein identifying the oblique target during the approach of the UVA is such that the oblique target is located in the center of a FOV of the at least one camera.

17. The method of claim 16 , wherein controlling the propulsion unit is based on an image including the tilted target located at a center of a FOV of the at least one camera.

18. controlling the propulsion unit receiving coordinates and a tilt angle of the tilted target; receiving a temporal tilt angle of the gimbal when the tilted target is located at a center of a FOV of the at least one camera; calculating a time position of the unmanned aerial vehicle based on the angle and the coordinates of the tilted target and the time tilt angle of the gimbal; determining a temporal population parameter based on the temporal location; 18. The method of claim 16 or claim 17, comprising:

19. The method of claim 18 , wherein the tilt angle is measured relative to the horizontal.

20. 20. The method of claim 18 or claim 19, wherein the temporal propulsion parameters include at least two of vertical velocity, vertical acceleration, horizontal velocity, and horizontal acceleration.

21. identifying a substantially horizontal target within the stream of images; controlling the gimble to rotate a corresponding camera such that both the oblique target and the substantially horizontal target are continuously identified in the image stream; controlling the propulsion unit to approach the substantially horizontal target while approaching the tilted target until the substantially horizontal target is located substantially vertically below the UVA; 21. The method of any one of claims 15 to 20, further comprising:

22. 22. The method of claim 21, wherein controlling the propulsion unit to approach the substantially horizontal target until the substantially horizontal target is located at the center of an image taken when the gimbals are tilted at -90 degrees relative to the horizon.

23. controlling the propulsion unit further receiving coordinates of the substantially horizontal target; calculating the time position of the unmanned aerial vehicle based also on the coordinates of the substantially horizontal target; 23. The method of claim 21 or claim 22, comprising:

24. 24. The method of any one of claims 21 to 23, wherein controlling the propulsion unit is to vertically approach the target until only the oblique target is identified in the image stream.

25. 25. The method of any one of claims 15 to 24, wherein the inclined target comprises a first ArUco marker and the substantially horizontal target comprises a second ArUco marker different from the first.

26. 26. The method according to any one of claims 18 to 25, wherein the tilt angle is between 20 degrees and 80 degrees.

27. A substantially horizontal target; an inclined target located a known distance from the substantially horizontal target and inclined at a known angle relative to a surface plane of the substantially horizontal target; A targeting system for landing an unmanned aerial vehicle (UAV), comprising:

28. 30. The targeting system of claim 27, wherein the substantially horizontal target comprises a first ArUco marker and the tilted target comprises a second ArUco marker different from the first ArUco marker.

29. The target system of claim 27 or 28, wherein the tilt angle is between 20 degrees and 80 degrees.

30. The target system of any one of claims 27 to 29, wherein the known distance is between 0.5m and 10m.

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