TECHNICAL FIELD

The invention relates to a system and method for autonomously landing a Vertical Take-off and Landing (VTOL) aircraft.

BACKGROUND

Current Vertical Take-Off and Landing (VTOL) aircrafts use one or more markers, located within a landing area, for geolocating the landing area and autonomously landing within it. The VTOL aircraft has a sensor (e.g., a camera) that can acquire the markers. Generally, the VTOL aircraft is landed with the sensor being substantially over a unique marker in the landing area, irrespective of a position of the sensor on the VTOL aircraft or a position of an object (e.g., a package or other payload) that is mounted to the VTOL aircraft.

References considered to be relevant as background to the presently disclosed subject matter are listed below. Acknowledgement of the references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.

Tang et al., “Quadrotor Going Through a Window and Landing: An Image-Based Visual Servo Control Approach,” Control Engineering Practice, 2021, 112:104827, considers the problem of controlling a quadrotor to go through a window and land on a planar target, the landing pad, using an Image-Based Visual Servo (IBVS) controller that relies on sensing information from two on-board cameras and an IMU. The maneuver is divided into two stages: crossing the window and landing on the pad. For the first stage, a control law is proposed that guarantees that the vehicle will not collide with the wall containing the window and will go through the window with non-zero velocity along the direction orthogonal to the window, keeping at all times a safety distance with respect to the window edges. For the landing stage, the proposed control law ensures that the vehicle achieves a smooth touchdown, keeping at all time a positive height above the plane containing the landing pad. For control purposes, the centroid vectors provided by the combination of the spherical image measurements of a collection of landmarks (corners) for both the window and the landing pad are used as position measurement. The translational optical flow relative to the wall, window edges, and landing plane is used as velocity cue.

Liu et al., “An Onboard Vision-Based System for Autonomous Landing of a Low- Cost Quadrotor on a Novel Landing Pad,” Sensors, 2019, 19.21 :4703, presents an onboard vision-based system for the autonomous landing of a low-cost quadrotor. A novel landing pad with different optical markers sizes is carefully designed to be robustly recognized at different distances. To provide reliable pose information in a GPS (Global Positioning Sy stem) -denied environment, a vision algorithm for real-time landing pad recognition and pose estimation is implemented. The dynamic model of the quadrotor is established and a system scheme for autonomous landing control is presented.

U.S. Patent Application Publication No. 2018/0150970 (“Benini et al.”), published on May 31, 2018, discloses a method for estimating a pose of a first object in relation to a second object, the second object comprising a visual marker comprising a plurality of ellipses, the method comprising: capturing a video image of the visual marker with an image capture device on the first object, then pre-processing frames of the video image on a graphics processing unit. The method comprises detecting the visual marker by finding contours in the frames to identify the plurality of ellipses and determining that a pattern of the plurality of ellipses match a known pattern of the visual marker. Then the method comprises obtaining coordinates of two or more of the plurality of ellipses of the visual marker, estimating the pose of the first object in relation to the second object by inputting the coordinates of the plurality of ellipses into a pose estimation algorithm, and filtering results of the pose estimation algorithm.

U.S. Patent Application Publication No. 2020/0130864 (“Brockers et al.”), published on April 30, 2020, discloses a method and system to provide the ability to autonomously operate an unmanned aerial system (UAS) over long durations of time. The UAS vehicle autonomously takes off from a take-off landing-charging station and autonomously executes a mission. The mission includes data acquisition instructions in a defined observation area. Upon mission completion, the UAS autonomously travels to a target landing-charging station and performs an autonomous precision landing on the target landing-charging station. The UAS autonomously re-charges via the target landingcharging station. Once re-charged, the UAS is ready to execute a next sortie. When landed, the UAS autonomously transmits mission data to the landing-charging station for in situ or cloud-based data processing.

U.S. Patent Application Publication No. 2018/0173245 (“Twining et al.”), published on June 21, 2018, presents systems, apparatuses and methods for landing an unmanned aircraft on a mobile structure. Sensors on the aircraft identify a predetermined landing area on a mobile structure. The aircraft monitors the sensor data to maintain its position hovering over the landing area. The aircraft estimates a future altitude of the surface of the landing area and determines a landing time that corresponds to a desired altitude of the surface of the landing area. The unmanned aircraft executes a landing maneuver to bring the aircraft into contact with the surface of the landing area at the determined landing time.

U.S. Patent Application Publication No. 2021/0129982 (“Collins et al.”), published on May 6, 2021, discloses a system and method for controlling an unmanned aerial vehicle (UAV) tethered from a mobile platform, the UAV system comprising: a UAV comprising one or more sensors, and one or more propellers; a tether attached to the UAV and to the mobile platform; a digital processing device comprising an operating system configured to perform executable instructions and a memory; and a computer program including instructions executable by the digital processing device to automatically control the UAV relative to the mobile platform comprising: a software module identifying the mobile platform; a software module estimating a real-time state of the mobile platform; and a software module automatically controlling three- dimensional real-time motion of the UAV based on the real-time state estimation of the mobile platform and data collected from the one or more sensors, such that the UAV is maintained at a predetermined position relative to the mobile platform.

U.S. Patent Application Publication No. 2018/0053139 (“Stoman”), published on February 22, 2018, discloses an aerial drone parcel delivery/transfer management server (ADPTMS) that is configured for facilitating flexible management of aerial drone parcel deliveries to or transfers between aerial drone landing pads (ADLPs). Each ADLP has a corresponding ADLP address that includes a unique ADLP identifier (e.g., a manufacturing serial number); current or most-recently known ADLP geolocation data (e.g., 2D or 3D geospatial coordinates); and possibly current or most-recently known ADLP elevation data. The ADPTMS can communicate with order management/fulfillment servers associated with online stores, which can communicate with aerial drone parcel delivery/transfer services for dispatching aerial drones to particular ADLP addresses as part of fulfilling online orders. An ADLP can present a machine-readable code such as a quick response (QR) code thereon (e.g., on a landing mat) that can be captured by an aerial drone and processed to verify the ADLP's identity. An ADLP can output local RF guiding signals and/or local optical guiding signals (e.g., infrared signals) to aid aerial drone navigation to the ADLP.

U.S. Patent Application Publication No. 2018/0357910 (“Hobbs et al.”), published on December 13, 2018, discloses a UAV landing system that can include a landing pad defining a landing area including a target point; a plurality of positioning radio transmitters positioned in a spaced apart relation and equidistant from the target point, each radio transmitter transmitting a ranging signal; and a position determination and aircraft navigation system at the incoming UAV to receive the ranging signals; determine a range to each positioning radio using the received ranging signals; compute a position of the UAV relative to the target point; determine a course for the UAV to a point above the target point of the landing pad; fly the UAV to the point above the target point of the landing pad, and cause the aircraft to descend vertically toward the target point when the UAV reaches the point above the target point.

U.S. Patent Application Publication No. 2016/0122038 (“Fleischman et al.”), published on May 5, 2016, discloses systems, methods, apparatuses, and landing platforms that are provided for visual and/or ground-based landing of unmanned aerial vehicles. The unmanned aerial vehicles may be capable of autonomously landing. Autonomous landings may be achieved by the unmanned air vehicles with the use of an imager and one or more optical markers on a landing platform. The optical markers may be rectilinear, monochromatic patterns that may be detected by a computing system on the unmanned aerial vehicle. Furthermore, the unmanned aerial vehicle may be able to automatically land by detecting one or more optical markers and calculating a relative location and/or orientation from the landing platform.

Orgeira-Crespo et al., “Methodology for Indoor Positioning and Landing of an Unmanned Aerial Vehicle in a Smart Manufacturing Plant for Light Part Delivery,” Electronics, 2020, 9.10: 1680, discloses a UAV that is used for performing light parts delivery to workstation operators within a manufacturing plant, where GPS is no valid solution for indoor positioning. A generic localization solution is designed to provide navigation using RFID received signal strength measures and sonar values. A system on chip computer is onboarded with two missions: first, compute positioning and provide communication with backend software; second, provide an artificial vision system that cooperates with UAV’s navigation to perform landing procedures. An Industrial Internet of Things solution is defined for workstations to allow wireless mesh communication between the logistics vehicle and the backend software.

Aksenov et al., “An Application of Computer Vision Systems to Unmanned Aerial Vehicle Autolanding,” International Conference on Interactive Collaborative Robotics, Springer, Cham, 2017, pp. 105-112, considers an approach to an auto-landing system for a multi-rotor unmanned aerial vehicle based on computer vision and visual markers usage instead of global positioning and radio navigation systems. Different architectures of auto-landing infrastructure are considered and requirements for key components of auto-landing systems are formulated.

U.S. Patent Application Publication No. 2017/0259912 (“Michini et al.”), published on September 14, 2017, discloses methods, systems, and apparatus, including computer programs encoded on computer storage media, for ground control point assignment and determination. One of the methods includes receiving information describing a flight plan for the UAV to implement, the flight plan identifying one or more waypoints associated with geographic locations assigned as ground control points. A first waypoint identified in the flight plan is traveled to, and an action to designate a surface at the associated geographic location is designated as a ground control point. Location information associated with the designated surface is stored. The stored location information is provided to an outside system for storage.

International Patent Application Publication No. 2020/176969 (“Razmara et al.”), published on September 10, 2020, discloses a method for photographing at least a portion of a subject, the method comprising: generating a photography scheme, the photography scheme comprising a set of photography control points, each of the photography control points comprising: a location of the platform relative to the subject; an orientation of the platform relative to the subject; and one or more photography parameters; determining a location and an orientation of the platform carrying the imaging system; navigating the platform to each of the photography control points and operating the imaging system to capture an image of the subject at each of the photography control points according to the associated photography parameters. A method of administering photodynamic therapy to a subject is also disclosed. U.S. Patent Application Publication No. 2016/0332748 (“Wang”), published on November 17, 2016, discloses systems and methods for docking an unmanned aerial vehicle (UAV) with a vehicle. The UAV may be able to distinguish a companion vehicle from other vehicles in the area and vice versa. The UAV may take off and/or land on the vehicle. The UAV may be used to capture images and stream the images live to a display within the vehicle. The vehicle may control the UAV. The UAV may be in communication with the companion vehicle while in flight.

U.S. Patent Application Publication No. 2022/0004796 (“Manako et al.”), published on January 6, 2022, discloses a survey marker, and an image processing apparatus, method, and program capable of accurately detecting a survey marker from a captured image obtained by image capturing. The survey marker has a planar shape and includes a plurality of circles concentrically disposed, the plurality of circles including adjacent circles each having a different color. A candidate region extraction unit extracts a candidate region from a captured image obtained by image capturing of the survey marker, the candidate region being a candidate of a region in which the survey marker appears. A feature amount extraction unit extracts a feature amount of the candidate region. A discrimination unit discriminates the survey marker on the basis of the feature amount. The technology can be applied to, for example, a case of detecting a survey marker installed on the ground from a captured image obtained by aerial image capturing.

Trittier et al., “Autopilot for Landing Small Fixed-Wing Unmanned Aerial Vehicles with Optical Sensors,” Journal of Guidance, Control, and Dynamics, 2016, 39.9:2011-2021, discloses an autopilot for landing fixed-wing mini-unmanned aerial vehicles. The objective is to land at a site, which is defined by three artificial visual markers placed by the operator in a triangular shape. A visual- servoing controller is developed, which uses direct feedback from, at minimum, an inertial navigation system, an airspeed sensor, and camera- image features. The image features are used to reconstruct the approach-path deviations based on the defined triangular marker geometry. In the final stage of the landing, the base markers of the triangle leave the camera’s field of view. A single optical marker and two optical-flow sensors are applied to control the touchdown phase. GENERAL DESCRIPTION

In accordance with a first aspect of the presently disclosed subject matter, there is provided a system for autonomously landing a Vertical Take-Off and Landing (VTOL) aircraft on a landing surface, the VTOL aircraft having a front end and a back end along a roll axis of the VTOL aircraft, and the system comprising: at least one primary sensor mounted to the VTOL aircraft, wherein a planar offset of the primary sensor from a center of the VTOL aircraft is known; and a processing circuitry configured to repeatedly perform the following until the landing of the VTOL aircraft: obtain a frame, captured by the primary sensor or another sensor that is mounted to the VTOL aircraft, the frame including at least one readable marker of a pattern of markers, the pattern of markers including one or more markers that are provided on the landing surface to enable the landing of the VTOL aircraft; identify the readable marker in the frame; and upon identifying the marker, generate, based on the marker, one or more maneuvering commands configured to control a movement of the VTOL aircraft; wherein the VTOL aircraft is landed with the primary sensor being offset from a predefined point that is designated on the landing surface prior to forming the pattern of markers, and wherein the primary sensor is capable of being at any orientation relative to the predefined point upon the landing of the VTOL aircraft.

In some cases, a yaw of the VTOL aircraft is not controllable.

In some cases, a payload is mounted to the VTOL aircraft below a given point on the VTOL aircraft, and wherein respective maneuvering commands configured to control the movement of the VTOL aircraft are generated to align the given point with the predefined point so that the payload is provided at the predefined point upon landing the VTOL aircraft.

In some cases, the payload is provided at the predefined point upon landing the VTOL aircraft, regardless of an orientation of the front end of the VTOL aircraft upon landing the VTOL aircraft.

In some cases, a yaw of the VTOL aircraft is not controllable.

In some cases, the pattern of markers includes one or more primary surrounding markers surrounding the predefined point, the primary surrounding markers being formed on the landing surface at a common and known given distance from the predefined point.

In some cases, the identified readable marker is a primary surrounding marker of the primary surrounding markers; wherein the processing circuitry is further configured to: determine, based on the primary surrounding marker, a virtual circular pattern surrounding the predefined point; and determine a sensor anchoring point on the virtual circular pattern, the sensor anchoring point being a point on the landing surface above which the primary sensor is to be located upon the landing of the VTOL aircraft; and wherein the maneuvering commands are generated, responsive to determining the sensor anchoring point, to control the movement of the VTOL aircraft so that the primary sensor will be substantially vertically aligned with the sensor anchoring point upon the landing of the VTOL aircraft.

In some cases, the sensor anchoring point is determined based on an orientation of the primary sensor relative to the VTOL aircraft.

In some cases, a payload is mounted to the VTOL aircraft at a second offset from the center of the VTOL aircraft, the second offset including a non-zero planar offset from the center of the VTOL aircraft; wherein the payload is to be provided at the predefined point upon the landing of the VTOL aircraft; and wherein a radius of the virtual circular pattern is a planar distance of the payload from the primary sensor.

In some cases, the sensor anchoring point is determined based on an orientation of the primary sensor relative to the VTOL aircraft, and further based on an offset of the primary sensor from the payload.

In some cases, each primary surrounding marker of the primary surrounding markers has an identifier, based on which a distance of the respective primary surrounding marker to the predefined point and an orientation of the respective primary surrounding marker relative to the predefined point is determined.

In some cases, the pattern of markers further includes one or more inner gust markers surrounding the predefined point, the inner gust markers being located closer to the predefined point than the primary surrounding markers.

In some cases, upon identifying one of the inner gust markers in one of the captured frames, the maneuvering commands are generated to maneuver the VTOL aircraft towards at least one of the primary surrounding markers.

In some cases, the pattern of markers further includes one or more outer gust markers surrounding the predefined point, the outer gust markers being located farther from the predefined point than the primary surrounding markers. In some cases, upon identifying one of the outer gust markers in one of the captured frames, the maneuvering commands are generated to maneuver the VTOL aircraft towards at least one of the primary surrounding markers.

In some cases, the pattern of markers includes a central marker that is formed on the predefined point.

In some cases, the identified marker is the central marker; wherein the processing circuitry is further configured to: determine a virtual circular pattern surrounding the predefined point, based on the central marker; and determine a sensor anchoring point on the virtual circular pattern, the sensor anchoring point being a point on the landing surface above which the primary sensor is to be located upon the landing of the VTOL aircraft; and wherein the maneuvering commands are generated, responsive to determining the sensor anchoring point, to control the movement of the VTOL aircraft so that the primary sensor will be substantially vertically aligned with the sensor anchoring point upon the landing of the VTOL aircraft.

In some cases, the sensor anchoring point is determined based on an orientation of the primary sensor relative to the VTOL aircraft.

In some cases, a payload is mounted to the VTOL aircraft at a second offset from the center of the VTOL aircraft, the second offset including a non-zero planar offset from the center of the VTOL aircraft; wherein the payload is to be provided at the predefined point upon the landing of the VTOL aircraft; and wherein a radius of the virtual circular pattern is a planar distance of the payload from the primary sensor.

In some cases, the sensor anchoring point is determined based on an orientation of the primary sensor relative to the VTOL aircraft, and further based on an offset of the primary sensor from the payload.

In some cases, the pattern of markers includes a sequence of two or more sequential markers that are configured to be successively identified, by the processing circuitry, and wherein, following an identification of a respective sequential marker of the sequential markers, the processing circuitry is configured to generate respective maneuvering commands for maneuvering the VTOL aircraft: (a) towards a next sequential marker of the sequential markers that is to be identified, (b) towards the landing surface, (c) towards both the next sequential marker and the landing surface, or (d) towards a predefined point, the predefined point not being the next sequential marker or the landing surface. In some cases, the pattern of markers further includes one or more primary surrounding markers surrounding the predefined point, the primary surrounding markers being formed on the landing surface at a common and known given distance from the predefined point; and wherein the maneuvering commands that are generated responsive to an identification of at least some of the sequential markers in the sequence result in a maneuvering of the VTOL aircraft such that the primary sensor is capable of capturing a respective frame that includes at least one primary surrounding marker of the primary surrounding markers.

In some cases, the pattern of markers includes one or more unique markers having a uniquely formatted identifier.

In some cases, a respective marker of the pattern of markers is at least one of: an optical marker, an acoustic marker, a color mark, an optical tag, a Radio Frequency (RF) tag, a Near Field Communication (NFC) tag, an Ultrawide Band (UWB) marker, a thermal marker, an infrared marker or an ultraviolet marker.

In accordance with a second aspect of the presently disclosed subject matter, there is provided a method for autonomously landing a Vertical Take-Off and Landing (VTOL) aircraft on a landing surface, the VTOL aircraft having a front end and a back end along a roll axis of the VTOL aircraft, and the method comprising: repeatedly performing the following, by a processing circuitry, until the landing of the VTOL aircraft: obtaining a frame, captured by a primary sensor or another sensor that is mounted to the VTOL aircraft, the frame including at least one readable marker of a pattern of markers, the pattern of markers including one or more markers that are provided on the landing surface to enable the landing of the VTOL aircraft, and wherein a planar offset of the primary sensor from a center of the VTOL aircraft is known; identifying the readable marker in the frame; and upon identifying the marker, generating, based on the marker, one or more maneuvering commands configured to control a movement of the VTOL aircraft; wherein the VTOL aircraft is landed with the primary sensor being offset from a predefined point that is designated on the landing surface prior to forming the pattern of markers, and wherein the primary sensor is capable of being at any orientation relative to the predefined point upon the landing of the VTOL aircraft.

In some cases, a yaw of the VTOL aircraft is not controllable.

In some cases, a payload is mounted to the VTOL aircraft below a given point on the VTOL aircraft, and wherein respective maneuvering commands configured to control the movement of the VTOL aircraft are generated to align the given point with the predefined point so that the payload is provided at the predefined point upon landing the VTOL aircraft.

In some cases, the payload is provided at the predefined point upon landing the VTOL aircraft, regardless of an orientation of the front end of the VTOL aircraft upon landing the VTOL aircraft.

In some cases, a yaw of the VTOL aircraft is not controllable.

In some cases, the pattern of markers includes one or more primary surrounding markers surrounding the predefined point, the primary surrounding markers being formed on the landing surface at a common and known given distance from the predefined point.

In some cases, the identified readable marker is a primary surrounding marker of the primary surrounding markers; and wherein the method further comprises: determining, based on the primary surrounding marker, a virtual circular pattern surrounding the predefined point; and determining a sensor anchoring point on the virtual circular pattern, the sensor anchoring point being a point on the landing surface above which the primary sensor is to be located upon the landing of the VTOL aircraft; and wherein the maneuvering commands are generated, responsive to determining the sensor anchoring point, to control the movement of the VTOL aircraft so that the primary sensor will be substantially vertically aligned with the sensor anchoring point upon the landing of the VTOL aircraft.

In some cases, the sensor anchoring point is determined based on an orientation of the primary sensor relative to the VTOL aircraft.

In some cases, a payload is mounted to the VTOL aircraft at a second offset from the center of the VTOL aircraft, the second offset including a non-zero planar offset from the center of the VTOL aircraft; wherein the payload is to be provided at the predefined point upon the landing of the VTOL aircraft; and wherein a radius of the virtual circular pattern is a planar distance of the payload from the primary sensor.

In some cases, the sensor anchoring point is determined based on an orientation of the primary sensor relative to the VTOL aircraft, and further based on an offset of the primary sensor from the payload.

In some cases, each primary surrounding marker of the primary surrounding markers has an identifier, based on which a distance of the respective primary surrounding marker to the predefined point and an orientation of the respective primary surrounding marker relative to the predefined point is determined.

In some cases, the pattern of markers further includes one or more inner gust markers surrounding the predefined point, the inner gust markers being located closer to the predefined point than the primary surrounding markers.

In some cases, upon identifying one of the inner gust markers in one of the captured frames, the maneuvering commands are generated to maneuver the VTOL aircraft towards at least one of the primary surrounding markers.

In some cases, the pattern of markers further includes one or more outer gust markers surrounding the predefined point, the outer gust markers being located farther from the predefined point than the primary surrounding markers.

In some cases, upon identifying one of the outer gust markers in one of the captured frames, the maneuvering commands are generated to maneuver the VTOL aircraft towards at least one of the primary surrounding markers.

In some cases, the pattern of markers includes a central marker that is formed on the predefined point.

In some cases, the identified marker is the central marker; wherein the method further comprises: determining a virtual circular pattern surrounding the predefined point, based on the central marker; and determining a sensor anchoring point on the virtual circular pattern, the sensor anchoring point being a point on the landing surface above which the primary sensor is to be located upon the landing of the VTOL aircraft; and wherein the maneuvering commands are generated, responsive to determining the sensor anchoring point, to control the movement of the VTOL aircraft so that the primary sensor will be substantially vertically aligned with the sensor anchoring point upon the landing of the VTOL aircraft.

In some cases, the sensor anchoring point is determined based on an orientation of the primary sensor relative to the VTOL aircraft.

In some cases, a payload is mounted to the VTOL aircraft at a second offset from the center of the VTOL aircraft, the second offset including a non-zero planar offset from the center of the VTOL aircraft; wherein the payload is to be provided at the predefined point upon the landing of the VTOL aircraft; and wherein a radius of the virtual circular pattern is a planar distance of the payload from the primary sensor. In some cases, the sensor anchoring point is determined based on an orientation of the primary sensor relative to the VTOL aircraft, and further based on an offset of the primary sensor from the payload.

In some cases, the pattern of markers includes a sequence of two or more sequential markers that are configured to be successively identified; and wherein, following an identification of a respective sequential marker of the sequential markers, respective maneuvering commands are generated to maneuver the VTOL aircraft: (a) towards a next sequential marker of the sequential markers that is to be identified, (b) towards the landing surface, (c) towards both the next sequential marker and the landing surface, or (d) towards a predefined point, the predefined point not being the next sequential marker or the landing surface.

In some cases, the pattern of markers further includes one or more primary surrounding markers surrounding the predefined point, the primary surrounding markers being formed on the landing surface at a common and known given distance from the predefined point; wherein the maneuvering commands that are generated responsive to an identification of at least some of the sequential markers in the sequence result in a maneuvering of the VTOL aircraft such that the primary sensor is capable of capturing a respective frame that includes at least one primary surrounding marker of the primary surrounding markers.

In some cases, the pattern of markers includes one or more unique markers having a uniquely formatted identifier.

In some cases, a respective marker of the pattern of markers is at least one of: an optical marker, an acoustic marker, a color mark, an optical tag, a Radio Frequency (RF) tag, a Near Field Communication (NFC) tag, an Ultrawide Band (UWB) marker, a thermal marker, an infrared marker or an ultraviolet marker.

In accordance with a third aspect of the presently disclosed subject matter, there is provided a non-transitory computer readable storage medium having computer readable program code embodied therewith, the computer readable program code, executable by a processing circuitry of a computer to perform a method for autonomously landing a Vertical Take-Off and Landing (VTOL) aircraft on a landing surface, the VTOL aircraft having a front end and a back end along a roll axis of the VTOL aircraft, and the method comprising: repeatedly performing the following, by a processing circuitry, until the landing of the VTOL aircraft: obtaining a frame, captured by a primary sensor or another sensor that is mounted to the VTOL aircraft, the frame including at least one readable marker of a pattern of markers, the pattern of markers including one or more markers that are provided on the landing surface to enable the landing of the VTOL aircraft, and wherein a planar offset of the primary sensor from a center of the VTOL aircraft is known; identifying the readable marker in the frame; and upon identifying the marker, generating, based on the marker, one or more maneuvering commands configured to control a movement of the VTOL aircraft; wherein the VTOL aircraft is landed with the primary sensor being offset from a predefined point that is designated on the landing surface prior to forming the pattern of markers, and wherein the primary sensor is capable of being at any orientation relative to the predefined point upon the landing of the VTOL aircraft.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the presently disclosed subject matter and to see how it may be carried out in practice, the subject matter will now be described, by way of non-limiting examples only, with reference to the accompanying drawings. The dimensions of components and features shown in the drawings are chosen for convenience and clarity of presentation and are not necessarily to scale. In the drawings:

Figs. 1A to IF are schematic illustrations of examples of a Vertical Take-Off and Landing (VTOL) aircraft and a primary sensor mounted to the VTOL aircraft, in accordance with the presently disclosed subject matter;

Fig. 2 is a block diagram of one example of an autonomous control system for autonomously controlling the VTOL aircraft, in accordance with the presently disclosed subject matter;

Fig. 3 is a schematic illustration of one example of a pattern of markers that is provided to autonomously land the VTOL aircraft, in accordance with the presently disclosed subject matter;

Fig. 4 is a flowchart illustrating one example of a sequence of operations for autonomously landing the VTOL aircraft using a pattern of one or more markers, in accordance with the presently disclosed subject matter;

Fig. 5A is a schematic illustration of an example of at least a part of a landing surface, in accordance with the presently disclosed subject matter; Fig. 5B is a schematic illustration of the at least a part of a landing surface that is illustrated in Fig. 5A, and one example of a frame, captured by the primary sensor, that includes a single primary surrounding marker that is located on the landing surface, in accordance with the presently disclosed subject matter; and

Fig. 5C is a schematic illustration of the at least part of a landing surface that is illustrated in Fig. 5A, and one example of a frame, captured by the primary sensor, that includes all of the primary surrounding markers and the central marker that are located on the landing surface, in accordance with the presently disclosed subject matter.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the presently disclosed subject matter. However, it will be understood by those skilled in the art that the presently disclosed subject matter 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 presently disclosed subject matter.

In the drawings and descriptions set forth, identical reference numerals indicate those components that are common to different embodiments or configurations.

Unless specifically stated otherwise, as apparent from the following discussions, it is appreciated that throughout the specification discussions utilizing terms such as “obtaining”, “generating”, “identifying”, “determining”, “calculating” or the like, include actions and/or processes, including, inter alia, actions and/or processes of a computer, that manipulate and/or transform data into other data, said data represented as physical quantities, e.g. such as electronic quantities, and/or said data representing the physical objects. The terms “computer”, “processor”, “processing circuitry” and “controller” should be expansively construed to cover any kind of electronic device with data processing capabilities, including, by way of non-limiting example, a personal desktop/laptop computer, a server (e.g., a cloud computing server), a computing system, a communication device, a smartphone, a tablet computer, a smart television, a processor (e.g. digital signal processor (DSP), a microcontroller, a field-programmable gate array (FPGA), an application specific integrated circuit (ASIC), etc.), a group of multiple physical machines sharing performance of various tasks, virtual servers co-residing on a single physical machine, any other electronic computing device, and/or any combination thereof.

As used herein, the phrase "for example," "an additional example", "such as", "for instance" and variants thereof describe non-limiting embodiments of the presently disclosed subject matter. Reference in the specification to "one case", "some cases", "other cases" or variants thereof means that a particular feature, structure or characteristic described in connection with the embodiment(s) is included in at least one embodiment of the presently disclosed subject matter. Thus, the appearance of the phrase "one case", "some cases", "other cases" or variants thereof does not necessarily refer to the same embodiment(s).

It is appreciated that, unless specifically stated otherwise, certain features of the presently disclosed subject matter, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the presently disclosed subject matter, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination.

In embodiments of the presently disclosed subject matter, fewer, more and/or different stages than those shown in Fig. 4 may be executed. Fig. 2 illustrates a general schematic of the system architecture in accordance with embodiments of the presently disclosed subject matter. Each module in Fig. 2 can be made up of any combination of software, hardware and/or firmware that performs the functions as defined and explained herein. The modules in Fig. 2 may be centralized in one location or dispersed over more than one location. In other embodiments of the presently disclosed subject matter, the system may comprise fewer, more, and/or different modules than those shown in Fig. 2.

Any reference in the specification to a method should be applied mutatis mutandis to a system capable of executing the method and should be applied mutatis mutandis to a non-transitory computer readable medium that stores instructions that once executed by a computer result in the execution of the method.

Any reference in the specification to a system should be applied mutatis mutandis to a method that may be executed by the system and should be applied mutatis mutandis to a non-transitory computer readable medium that stores instructions that may be executed by the system. Any reference in the specification to a non-transitory computer readable medium should be applied mutatis mutandis to a system capable of executing the instructions stored in the non-transitory computer readable medium and should be applied mutatis mutandis to method that may be executed by a computer that reads the instructions stored in the non-transitory computer readable medium.

Attention is now drawn to Figs. 1A to IF, schematic illustrations of examples of a Vertical Take-Off and Landing (VTOL) aircraft 110 and a primary sensor 120 mounted to the VTOL aircraft 110, in accordance with the presently disclosed subject matter.

In accordance with the presently disclosed subject matter, at least one primary sensor 120 is mounted to the VTOL aircraft 110 to capture frames (i.e., sensor frames) (exemplary frames 520 and 550 are illustrated in Figs. 5B and 5C, respectively), including, in some cases, frames of a landing surface on or above which the VTOL aircraft 110 is to be landed. A planar (not vertical) offset of the primary sensor 120 from a center 134 of the VTOL aircraft 110 is known, the known planar offset being non-zero, as illustrated in Figs. 1A to IF, or zero (the primary sensor 120 can also be at a vertical offset from the VTOL aircraft 110). In some cases, primary sensor 120 can be directly mounted to the VTOL aircraft 110 under the VTOL aircraft 110. Alternatively, in some cases, primary sensor 120 can be indirectly mounted to the VTOL aircraft 110, for example, along, above or below a roll axis 138 of the VTOL aircraft 110. For example, a rigid mechanical structure (e.g., Figs. IE and IF, rig 148) can be connected between the VTOL aircraft 110 and the primary sensor 120, wherein a first end (e.g., Figs. IE and IF, 152) of the rigid mechanical structure (e.g., 148) is connected to the VTOL aircraft 110, and wherein the primary sensor 120 is connected to a sensor mounting structure (e.g., Figs. IE and IF, 160) that is mounted at a second end (e.g., Figs. IE and IF, 154) of the rigid mechanical structure (e.g., 148), the second end (e.g., 154) of the rigid mechanical structure (e.g., 148) being opposite the first end (e.g., 154) of the rigid mechanical structure (e.g., 148). In some cases, the primary sensor 120 can be indirectly mounted to the VTOL aircraft 110 (e.g., via a rigid mechanical structure (e.g., 148), as detailed above) such that the primary sensor 120 is not located under the VTOL aircraft 110, as illustrated in Figs. IE and IF. Fig. IF provides an example of a primary sensor 120 that is indirectly mounted to the VTOL aircraft 110 below the roll axis 138 of the VTOL aircraft 110. The VTOL aircraft 110 can be manned (e.g. a manned helicopter, a manned drone, etc.) or unmanned. In some cases, the VTOL aircraft 110 can be an unmanned drone, which can optionally be autonomous.

A pattern of markers (e.g., 300) (not shown in Figs. 1A to IF), on the basis of which the VTOL aircraft 110 is controlled, is formed. In some cases, the pattern of markers (e.g., 300) includes markers that are formed for autonomously landing the VTOL aircraft 110 on a landing surface. The pattern of markers (e.g., 300) includes one or more markers. Prior to forming the pattern of markers (e.g., 300), a predefined point 305 (not shown in Figs. 1A to IF) is designated on the landing surface (if landing of the VTOL aircraft 110 is to be performed based on the pattern of markers (e.g., 300)). The predefined point 305 can be the center of the landing surface, although the predefined point 305 can also be at another location on the landing surface. The pattern of markers (e.g., 300) can be formed based on the predefined point 305 and the known planar offset of the primary sensor 120 from the center 134 of the VTOL aircraft 110, as detailed further herein, inter alia with reference to Fig. 3. In particular, the pattern of one or more primary surrounding markers 310 (not shown in Figs. 1A to IF) is formed based on the predefined point 305 and the known planar offset of the primary sensor 120 from the center 134 of the VTOL aircraft 110, as detailed further herein, inter alia with reference to Fig. 3.

In some cases, the VTOL aircraft 110 can be controlled so that a center 134 of the VTOL aircraft 110 will be vertically aligned (or substantially vertically aligned) with the predefined point 305 upon a landing of the VTOL aircraft 110. That is, the VTOL aircraft 110 can be controlled so that the center 134 of the VTOL aircraft 110 will be on, about, directly above, or substantially directly above the predefined point 305 (i.e., (substantially) vertically aligned with the predefined point 305) upon the landing of the VTOL aircraft 110. Alternatively, in some cases, the VTOL aircraft 110 can be controlled so that a center 134 of the VTOL aircraft 110 will be vertically unaligned with the predefined point 305 upon the landing of the VTOL aircraft 110 (e.g., in order to provide a payload at the predefined point 305, as detailed further herein). Indeed, in some cases, the VTOL aircraft 110 can be controlled so that no part of the VTOL aircraft 110 is vertically aligned with the predefined point 305 upon the landing of the VTOL aircraft 110. It is to be emphasized here that the landing of the VTOL aircraft 110 can occur when the VTOL aircraft 110 touches down on the landing surface or descends to a predefined height above the landing surface. For example, legs that are provided in or mounted to the VTOL aircraft 110 can be lowered as the VTOL aircraft 110 descends towards the landing surface, such that the legs contact the landing surface when the VTOL aircraft 110 reaches a predefined height above the landing surface. As an additional example, when the VTOL aircraft 110 descends to a predefined height above the landing surface, a payload (e.g., package) for delivery that is mounted on the VTOL aircraft 110 can be dropped onto the landing surface. The releasing of the payload from the VTOL aircraft 110 can represent the landing of the VTOL aircraft 110.

To illustrate why it may be desirable for the center 134 of the VTOL aircraft 110 to be vertically unaligned with the predefined point 305 upon the landing of the VTOL aircraft 110, the following example is provided. A payload (for example, a package) is mounted to the VTOL aircraft 110 below a given point 145 on the VTOL aircraft 110. Moreover, in this example, it is desired to land the VTOL aircraft 110 so that the pay load will be provided at (on or substantially on) the predefined point 305 upon the landing of the VTOL aircraft 110. To achieve this, the given point 145 on the VTOL aircraft 110 is to be substantially vertically aligned with the predefined point 305 upon the landing of the VTOL aircraft 110, such that the center 134 of the VTOL aircraft 110 is vertically unaligned with the predefined point 305 upon the landing of the VTOL aircraft 110 (regardless of the orientation of the front end 126 of the VTOL aircraft 110). It is to be noted that a payload can be provided on the landing surface (for example, at the predefined point 305) in any number of conceivable ways, for example, by laying the pay load on the landing surface, lowering the pay load from the VTOL aircraft 110 to the landing surface (e.g., by a winch), throwing (i.e., dropping) the payload to the landing surface, etc.

Primary sensor 120 is configured to capture frames during part or all of a flight of the VTOL aircraft 110, including, in some cases, during a landing process for landing the VTOL aircraft 110. At least some (e.g., all) of the captured frames include at least one readable complete marker of the one or more markers in the pattern of markers (e.g., 300). Following the capture of a complete marker in a respective frame of the captured frames, by the primary sensor 120, and identification of the marker, by an autonomous control system 200 (not shown in Figs. 1A to IF), one or more maneuvering commands for controlling the movement of the VTOL aircraft 110 can be generated, by the autonomous control system 200, based on the identified marker. For the purposes of this disclosure, the autonomous control system 200 includes the primary sensor 120 and any other sensor, if any, that captures frames, and further includes all processing circuitry of the VTOL aircraft 110 that performs operations that are to be performed in order to generate maneuvering commands for controlling the VTOL aircraft 110. The processing circuitry can be included in a single device or in multiple devices. In some cases, the maneuvering commands are provided to a central control system of the VTOL aircraft 110 that is configured to maneuver the VTOL aircraft 110, in accordance with the maneuvering commands. The autonomous control system 200 can communicate with the central control system, while residing or not residing on the same hardware infrastructure as the central control system. However, in some cases, the maneuvering of the VTOL aircraft 110 in accordance with the maneuvering commands can be performed by the autonomous control system 200 (e.g., the autonomous control system 200 also acts as the central control system (AUTO PILOT) of the VTOL aircraft 110). Alternatively, in some cases, the maneuvering commands can be provided to a human operator of the VTOL aircraft 110 as a recommendation, etc.

Figs. 1A to ID are identical, with the exception that an orientation of the primary sensor 120 is different in each of Figs. 1A to ID. The VTOL aircraft 110 in Figs. 1A to ID includes a front end 126 and a back end 136 along a roll axis 138 of the VTOL aircraft 110. The primary sensor 120 in Figs. 1A to ID is mounted to the VTOL aircraft 110 under a point on the VTOL aircraft 110 along a longitudinal axis 132 of a left wing 140 of the VTOL aircraft 110 (the views of the VTOL aircraft 110 in Figs. 1A to ID are from below the VTOL aircraft 110). However, the primary sensor 120 can be mounted to the VTOL aircraft 110 under any other point on the VTOL aircraft 110, including, inter alia, under the center 134 of the VTOL aircraft 110. In some cases, the primary sensor 120 can be indirectly mounted to the VTOL aircraft (e.g., via a rigid mechanical structure (e.g., 148), as detailed above, inter alia with reference to Figs. IE and IF), even at a point that is not underneath the VTOL aircraft 110, for example, as detailed above, inter alia with reference to Figs. IE and IF. The VTOL aircrafts 110 in Figs. 1A to IF are illustrative. That is, the VTOL aircraft of the present disclosure can be different than the VTOL aircrafts that are illustrated in Figs. 1A to IF.

It is an object of the present disclosure to land the VTOL aircraft 110 with the primary sensor 120 being offset from the predefined point 305, wherein the primary sensor 120 is capable of being at any orientation relative to the predefined point 305 upon the landing of the VTOL aircraft 110. In some cases, a yaw of the VTOL aircraft 110 is not controllable. For example, the VTOL aircraft 110 can be designed such that a front end 126 of the VTOL aircraft 110 always opposes the direction of the wind, and, as indicated above, in some cases, the VTOL aircraft 110 cannot actively change the yaw angle, which is passively determined in accordance with the direction of the wind (feathering). Since the primary sensor 120, which is offset from the predefined point 305 upon the landing of the VTOL aircraft 110, is capable of being at any orientation relative to the predefined point 305 upon the landing of the VTOL aircraft 110, the VTOL aircraft 110 can be landed as desired (for example, for a payload (e.g., 145) that is mounted to the VTOL aircraft 110 to be aligned or substantially aligned with the predefined point 305 upon landing the VTOL aircraft 110), even if the rotational movement 122 of the VTOL aircraft 110 about its yaw axis 124 is not controllable.

Figs. 1A to ID illustrate different orientations of the primary sensor 120. For example, in Fig. 1A, the primary sensor 120 is oriented towards the center 134 of the VTOL aircraft 110 along a pitch axis (the positive direction of the y-axis of a sensor frame (not shown) that is captured by the primary sensor 120 is oriented towards the center 134 of the VTOL aircraft 110 in parallel to the pitch axis while the primary sensor 120 is facing towards the ground), as indicated by the white arrow; in Fig. IB, the primary sensor 120 is oriented towards the front end 126 of the VTOL aircraft 110 in parallel to the roll axis 138 (the positive direction of the y-axis of a sensor frame that is captured by the primary sensor 120 is oriented towards the front end 126 of the VTOL aircraft 110 in parallel to the roll axis while the primary sensor 120 is facing towards the ground), as indicated by the black arrow (it is to be noted that the VTOL aircraft 110 may be able to fly in any direction, such that the front end 126 need not be the lead end of the VTOL aircraft 110 during the flight of the VTOL aircraft 110); in Fig. 1C, the primary sensor 120 is oriented along the longitudinal axis 132 of the left wing of the VTOL aircraft 110 away from the center 134 of the VTOL aircraft 110 along the pitch axis (the negative direction of the y-axis of a sensor frame that is captured by the primary sensor 120 is oriented towards the center 134 of the VTOL aircraft 110 in parallel to the pitch axis while the primary sensor 120 is facing towards the ground), as indicated by the silver arrow; and in Fig. ID, the primary sensor 120 is oriented towards the back end 136 of the VTOL aircraft 110 in parallel to the roll axis 138 (the negative direction of the y-axis of a sensor frame that is captured by the primary sensor 120 is oriented towards the front end of the VTOL aircraft 110 in parallel to the roll axis while the primary sensor 120 is facing towards the ground), as indicated by the gray arrow.

Attention is now drawn to Fig. 2, a block diagram of one example of an autonomous control system 200 that is configured to autonomously control the VTOL aircraft 110, in accordance with the presently disclosed subject matter.

In accordance with the presently disclosed subject matter, system 200 can be configured to include at least one primary sensor 120 that is directly or indirectly mounted to the VTOL aircraft 110, as detailed earlier herein, inter alia with reference to Figs. 1A to IF.

In some cases, system 200 can further comprise or be otherwise associated with a data repository 220 (e.g. a database, a storage system, a memory including Read Only Memory - ROM, Random Access Memory - RAM, and/or any other type of memory, etc.) configured to store data. However, it is to be emphasized that the system 200 does not need to comprise or be otherwise associated with a data repository 220, since the markers in the pattern of markers (e.g., 300) can store data regarding their location and/or orientation, and, optionally, additional information that enables the landing of the VTOL aircraft 110. In some cases, in which the system 200 comprises or is otherwise associated with a data repository 220, the data repository 220 can be further configured to enable retrieval and/or update and/or deletion of the stored data. It is to be noted that in some cases, data repository 220 can be distributed.

System 200 can be further configured to include a processing circuitry 230. Processing circuitry 230 can be one or more processing units (e.g. central processing units), microprocessors, microcontrollers (e.g. microcontroller units (MCUs)) or any other computing devices or modules, including multiple and/or parallel and/or distributed processing units, which are adapted to independently or cooperatively process data, including data for autonomously landing the VTOL aircraft 110.

Processing circuitry 230 can be configured to autonomously control the VTOL aircraft 110, as detailed further herein, inter alia with reference to Figs. 3, 4, 5B and 5C.

Attention is now drawn to Fig. 3, a schematic illustration of one example of a pattern of markers 300 that is provided to autonomously land the VTOL aircraft 110, in accordance with the presently disclosed subject matter. In accordance with the presently disclosed subject matter, the pattern of markers (e.g., 300) that is provided, for example, to autonomously land the VTOL aircraft 110 includes one or more markers (e.g., 310, 320, 330, 340, etc.) that are provided on a landing surface. If the primary sensor 120 is not located under the center 134 of the VTOL aircraft 110 (i.e., there is a non-zero planar offset between the primary sensor 120 and the center 134 of the VTOL aircraft 110), the pattern of markers (e.g., 300) based on which the VTOL aircraft 110 can be autonomously landed includes one or more primary surrounding markers (e.g., 310) surrounding a predefined point 305 on the landing surface. The primary surrounding markers (e.g., 310) are at a common and known given distance R from the predefined point 305, the predefined point 305 being designated on the landing surface prior to forming the pattern of markers (e.g., 300). For now, it is to be noted that the given distance R of the one or more primary surrounding markers (e.g., 310) from the predefined point 305 is determined so that there will be at least one complete primary surrounding marker 310 in at least one of the last frames that are captured by the primary sensor 120 prior to the landing of the VTOL aircraft 110. Since primary sensor 120 is configured to capture the last frames prior to the landing of the VTOL aircraft 110, the given distance R of the primary surrounding markers 310 from the predefined point 305 is based on the known planar offset of the primary sensor 120 from the center 134 of the VTOL aircraft 110 (the pattern of the primary surrounding markers 310 is designed so that at least one of the primary surrounding markers 310 is readable by the primary sensor 120 when the primary sensor 120 captures one of the last frames prior to the landing of the VTOL aircraft 110). The last frame can be captured responsive to a command to land the VTOL aircraft 110, for example, when the VTOL aircraft 110 descends to a given height above the landing surface. The predefined point 305 can be the center of the landing surface or any another location on the landing surface.

Each of the primary surrounding markers (e.g., 310) has an identifier (e.g., 315). In some cases, the identifier 315 of a respective primary surrounding marker 310 can include data regarding: (a) the distance of the respective primary surrounding marker to the predefined point 305 and (b) the orientation of the respective primary surrounding marker relative to the predefined point 305. In some cases, the orientation of a respective primary surrounding marker 310 relative to the predefined point 305 can be determined based on an orientation of the identifier 315 of the respective primary surrounding marker 310 relative to the predefined point 305, and the distance of the respective primary surrounding marker 310 relative to the predefined point 305 can be determined based on a form of the identifier 315 of the respective primary surrounding marker 310, for example, as is the case for all of the primary surrounding markers 310 in Fig. 3 (system 200 can be configured to correlate the form of the identifier 315 of the respective primary surrounding marker 310 with the respective primary surrounding marker 310 being a respective primary surrounding marker, wherein the system stores a distance R of each of the primary surrounding markers 310 from the predefined point 305). In some cases, the orientation of a respective primary surrounding marker 310 relative to the predefined point 305 can be determined based on an orientation of the identifier 315 of the respective primary surrounding marker 310 relative to the predefined point 305, for example, as is the case for all of the primary surrounding markers 310 in Fig. 3, and the distance of the respective primary surrounding marker 310 from the predefined point 305 can be determined based on data regarding the distance that is stored in the identifier 315 of the respective primary surrounding marker 310. In some cases, the identifier 315 of a respective primary surrounding marker 310 can be configured to include data that indicates that the respective primary surrounding marker is a primary surrounding marker, wherein the orientation of the respective primary surrounding marker 310 relative to the predefined point 305 can be determined based on data that is included in the identifier 315 or based on an orientation of the identifier 315 relative to the predefined point 305 (in this case, the system 200 stores a distance R of each of the primary surrounding markers 310 from the predefined point 305). In some cases, the identifiers 315 of the primary surrounding markers 310 can store data regarding the size of the primary surrounding markers 310 (the data regarding the size of the primary surrounding markers 310 can also be stored in a data repository 220 associated with the system 200).

The one or more primary surrounding markers 310 can be one of the following: optical markers (as illustrated in Fig. 3), acoustic markers, color marks, optical tags, Radio Frequency (RF) tags, Near Field Communication (NFC) tags, Ultrawide Band (UWB) markers, thermal markers, infrared markers, ultraviolet (UV) markers, or any other type of markers, provided that the at least one primary sensor 120 is capable of capturing the primary surrounding markers 310.

Turning to the exemplary pattern of markers 300 that is illustrated in Fig. 3, the exemplary pattern of markers 300 includes, in addition to primary surrounding markers 310, the following markers: (a) a central marker 320 that is located on the predefined point 305, (b) a plurality of inner gust markers 330 that are at a distance Di from the predefined point 305 that is less than the distance R of the primary surrounding markers 310 from the predefined point 305 (i.e., the inner gust markers 330 are closer to the predefined point 305 than the primary surrounding markers 310), and (c) a plurality of outer gust markers 340 that are at a distance D2 from the predefined point 305 that is greater than the distance R of the primary surrounding markers 310 from the predefined point 305 (i.e., the outer gust markers 340 are farther from the predefined point 305 than the primary surrounding markers 310). It is to be noted that the pattern of markers 300 does not have to include any one of: the central marker 320, the inner gust markers 330, or the outer gust markers 340.

If a central marker 320 is included in the pattern of markers 300, the central marker 320 does not have to be centered over the predefined point 305.

In addition, if inner gust markers 330 are included in the pattern of markers, not all of the inner gust markers 330 have to be at a same distance (e.g., Di) from the predefined point 305, as in Fig. 3, but rather different inner gust markers can be at different distances from the predefined point 305 that are less than the given distance R of the primary surrounding markers 310 from the predefined point 305. Likewise, if outer gust markers 340 are included in the pattern of markers, not all of the outer gust markers 340 have to be at a same distance (e.g., D2) from the predefined point 305, as in Fig. 3, but rather different outer gust markers can be at different distances from the predefined point 305 that are greater than the given distance R of the primary surrounding markers 310 from the predefined point 305.

Each of the markers in the pattern of markers (e.g., 300) has an identifier. Turning to the exemplary pattern of markers 300 in Fig. 3, central marker 320 has an identifier 325, the inner gust markers 330 have an identifier 335, and the outer gust markers 340 have an identifier 345.

In some cases, the identifier of a respective marker in the pattern of markers (e.g., 300) stores data regarding an orientation of the respective marker relative to: (a) the predefined point 305 or (b) another marker to be captured following the capturing of the respective marker. In some cases, an orientation of the identifier of a respective marker in the pattern of markers (e.g., 300) can indicate an orientation of the respective marker relative to: (a) the predefined point 305 or (b) another marker to be captured following the capturing of the respective marker. For example, in Fig. 3, the orientation of each of the inner gust markers 330 and each of the outer gust markers 340 relative to the predefined point 305 is determined based on an orientation of the identifier (335, 345) of the respective gust marker (330, 340). In some cases, the identifier of a respective marker in the pattern of markers (e.g., 300) does not store data regarding the orientation of the respective marker relative to the predefined point 305 or another marker to be captured following the capturing of the respective marker, and the orientation of the respective marker relative to the predefined point 305 or to the another marker is not indicated by an orientation of the identifier. For example, in some cases, orientation data regarding a respective inner gust marker or a respective outer gust marker is not stored in the respective gust marker and is not indicated by an orientation of the respective gust marker (e.g., the identifier of a respective gust marker is formed to inform the system 200 when the VTOL aircraft 110 passes over the respective gust marker, regardless of the orientation of the respective gust marker). In some cases, the identifier of a respective marker in the pattern of markers (e.g., 300) can store data regarding a distance of the respective marker to the predefined point 305 or to another marker that is to be captured following the capturing of the respective marker. In some cases, the identifier of a respective marker in the pattern of markers (e.g., 300) can also store data regarding the size of the respective marker.

In some cases, the type of a respective marker of the pattern of markers can be identified based on the identifier of the respective marker. For example, a central marker (e.g., 320) can be identified as a central marker based on a form or any other characteristic of the identifier (e.g., 325) and data stored in the data repository 220 that associates the form or the other characteristic of the identifier with the identifier being of a central marker. As an additional example, a central marker can be identified as a central marker based on data stored in the central marker that indicates that the central marker is positioned over the predefined point 305.

Moreover, in some cases, one or more of the inner gust markers (e.g., 330), if any, and/or one or more of the outer gust markers (e.g., 340), if any, can include an identifier that identifies the respective marker as an inner gust marker or an outer gust marker. For example, the identifier can identify a respective inner gust marker or a respective outer gust marker based on a color, a geometrical shape, and/or any other characteristic of the gust marker. For example, the pattern of markers can include a single inner gust marker (not as shown in Fig. 3) that fully surrounds the predefined point 305, wherein a color, a shape, and/or another characteristic of the inner gust marker is the identifier of the inner gust marker (e.g., the inner gust marker is red and circular), and is indicative of the inner gust marker being an inner gust marker. As an additional example, the pattern of markers can include a single outer gust marker (not as shown in Fig. 3) that fully surrounds the predefined point 305, wherein a color, a shape and/or another characteristic of the outer gust marker is the identifier of the outer gust marker (e.g., the outer gust marker is green and square), and is indicative of the outer gust marker being an outer gust marker. It is to be noted that, in some cases, the pattern of markers can include both a single inner gust marker and a single outer gust marker, as detailed above.

Each of the markers in the pattern of markers (e.g., 300) can be one of the following: an optical marker (the central marker 320, inner gust markers 330 and outer gust markers 340 that are shown in Fig. 3 are optical markers), an acoustic marker, a color mark, an optical tag, a Radio Frequency (RF) tag, a Near Field Communication (NFC) tag, an Ultrawide Band (UWB) marker, a thermal marker, an infrared marker, an ultraviolet (UV) marker, or any other type of marker that can be captured by a sensor (e.g., primary sensor 120) that is mounted on the VTOE aircraft 110, and identified by the system 200.

In some cases, as illustrated in Fig. 3, all of the inner gust markers (e.g., 330) include a common identifier (e.g., 335), and/or all of the outer gust markers (e.g., 340) include a common identifier (e.g., 345). Alternatively, in some cases, at least one of the inner gust markers and/or at least one of outer gust markers has a uniquely formatted identifier, unique to the respective inner/outer gust marker (e.g., a unique barcode, etc.).

Attention is now drawn to Fig. 4, a flowchart illustrating one example of a sequence of operations 400 for autonomously landing the VTOL aircraft 110 using a pattern of one or more markers (e.g., 300), in accordance with the presently disclosed subject matter.

In accordance with the presently disclosed subject matter, system 200 is configured, e.g., using processing circuitry 230, to obtain frames that are captured by the at least one primary sensor 120 or a different sensor, different than the primary sensor 120, during the landing process for landing the VTOL aircraft 110 (block 404).

Upon obtaining a captured frame (block 404), system 200 is further configured, e.g., using processing circuitry 230, to identify a readable marker (e.g., 310, 320, 330, 340, etc.) in the captured frame, provided that the captured frame includes at least one readable marker, readable by the respective sensor (e.g., 120) that captured the captured frame (block 408).

If a marker is identified in the captured frame, and a virtual circular pattern on the landing surface cannot be determined based on the identified marker (block 412), system 200 can be configured, e.g., using processing circuitry 230, to generate, based on the identified marker, maneuvering commands configured to control the maneuvering of the VTOL aircraft 110 (block 416), without determining a virtual circular pattern.

In some cases, system 200 can be configured, e.g., using processing circuitry 230, to identify a sequence of two or more sequential markers in the pattern of markers over a plurality of frames that are captured by the primary sensor 120 or another sensor mounted to the VTOL aircraft 110. In some cases, the sequential markers can be configured to be successively identified. In some cases, one or more of the identified sequential markers includes an identifier based on which a specific subsequent sequential marker is to be identified following the identification of the respective identified sequential marker. In some cases, the identifier of the respective identified sequential marker can have an orientation that points in the direction of the specific subsequent sequential marker. Alternatively, in some cases, data that is indicative of an orientation of the respective identified sequential marker relative to the specific subsequent sequential marker can be stored in the identifier of the respective identified sequential marker or in the data repository 220. System 200 can be configured, based on the known orientation of the respective identified sequential marker relative to the specific subsequent sequential marker, to generate maneuvering commands for maneuvering the VTOL aircraft 110. The maneuvering commands can be generated for maneuvering the VTOL aircraft 110: (a) towards the specific subsequent sequential marker, (b) towards the landing surface, (c) towards both the specific subsequent sequential marker and the landing surface, or (d) towards a predefined point not listed above (for example, a point at which the controlling of the VTOL aircraft 110 is transferred to another source for maneuvering the VTOL aircraft 110). In some cases, the maneuvering commands that are generated responsive to an identification of at least some of the sequential markers (e.g., a given sequential marker can be skipped if the successive sequential marker that is successive to the given sequential marker is already identified) in the sequence of sequential markers result in a maneuvering of the VTOL aircraft 110 such that the primary sensor 120 is capable of capturing a respective frame that includes at least one primary surrounding marker of the primary surrounding markers 310.

One or more of the identified markers during the landing process includes an identifier based on which an orientation of the respective identified marker relative to the predefined point 305 can be determined. In some cases, the orientation of the respective marker relative to the predefined point 305 can be determined based on an orientation of the identifier of the respective identified marker relative to the predefined point 305. Alternatively, in some cases, data that is indicative of an orientation of the respective identified marker relative to the predefined point 305 can be stored in the identifier of the respective identified marker or in the data repository 220. System 200 can be configured, based on the known orientation of the respective identified marker relative to the predefined point 305, to generate maneuvering commands for maneuvering the VTOL aircraft 110.

In some cases, in one or more of the captured frames captured by primary sensor 120 during the landing process, the respective captured frame can include at least two readable markers in the pattern of markers (e.g., 300) that are read by the primary sensor 120 and identified by the system 200. In such cases, system 200 can be configured, e.g., using processing circuitry 230, to generate, based on one of the readable markers, the maneuvering commands for maneuvering the VTOL aircraft 110, and, in some cases, a virtual circular pattern (e.g., 530) on the landing surface (the generation of the virtual circular pattern is discussed below). The readable marker, of the readable markers, based on which the maneuvering commands are generated or the virtual circular pattern (e.g., 530) is generated, can be determined in any number of ways, for example, based on at least one preset rule that is provided to the system 200 (e.g., the preset rule is provided in the data repository 220 that is associated with system 200), the preset rule defining based on which of the readable markers the maneuvering commands are to be generated or the virtual circular pattern (e.g., 530) is to be generated. For example, the preset rule can define that when both the central marker 320 and at least one of the primary surrounding markers 310 are read by primary sensor 120, system 200 is to generate the maneuvering commands based on the read primary surrounding marker 310.

Upon identifying a marker in a captured frame, captured by the primary sensor 120, based on which a virtual circular pattern (e.g., 530) on the landing surface can be determined (block 412), system 200 can be configured (e.g., using processing circuitry 230), in some cases, to determine the virtual circular pattern (e.g., 530), as in the flowchart of Fig. 4, and as detailed further herein, inter alia with reference to Figs. 5B and 5C (block 420). Additionally, in some cases, for example, if the VTOL aircraft 110 is significantly above the landing surface, system can be configured to generate maneuvering commands without determining the virtual circular pattern (e.g., 530), even if the virtual circular pattern can be determined based on the identified marker. With respect to the pattern of markers in Figs. 3 and 5A to 5C, the virtual circular pattern 530 can be determined, for example, following the identification of either the central marker 320 or one of the primary surrounding markers 310 in a captured frame (e.g., 520, 550). In order to land the VTOL aircraft 110 with the primary sensor 120 being offset from the predefined point 305, and wherein the primary sensor 120 is capable of being at any orientation relative to the predefined point 305 upon the landing of the VTOL aircraft 110, the virtual circular pattern (e.g., 530) is to be determined.

Upon determining the virtual circular pattern (e.g., 530), system 200 can be configured, e.g., using processing circuitry 230, to determine a sensor anchoring point (e.g., 536) on the virtual circular pattern (e.g., 530), as detailed further herein, inter alia with reference to Figs. 5B and 5C, the sensor anchoring point (e.g., 536) being the point on the virtual circular pattern (e.g., 530) over which the sensor 120 is to be located upon a landing of the VTOL aircraft 110 (block 424). Following the determination of the sensor anchoring point (e.g., 536), system 200 can be configured, e.g., using processing circuitry 230, to generate maneuvering commands for maneuvering the VTOL aircraft 110, as detailed below, inter alia with reference to Figs. 5B and 5C.

To explain and illustrate (a) how the virtual circular pattern (e.g., 530) is determined and (b) how the sensor anchoring point (e.g., 536) on the virtual circular pattern (e.g., 530) is determined, attention is now drawn to Figs. 5A to 5C. Fig. 5A is a schematic illustration of an example of at least part of a landing surface 500, in accordance with the presently disclosed subject matter. The at least part of the landing surface 500 in Fig. 5A include a central marker 320 and four primary surrounding markers (310-a, 310-b, 310-c, 310-d). In Fig. 5A, each of the primary surrounding markers (310-a, 310-b, 310-c, 310-d) includes a common identifier 315. Each of the primary surrounding markers (310-a, 310-b, 310-c, 310-d) can be identified, by system 200, as a primary surrounding marker, based on the common identifier 315. Moreover, an orientation of an identified primary surrounding marker (310-a, 310-b, 310-c or 310-d) relative to the predefined point 305 can be determined, by system 200, based on a reading of the orientation of the respective primary surrounding marker (based, for example, on the form of the respective primary surrounding marker or data stored in the respective primary surrounding marker). In addition, the distance of the identified primary surrounding marker (310-a, 310-b, 310-c or 310-d) relative to the predefined point 305 can be determined, by system 200, based on data that is stored in the identified marker or in a data repository. Upon determining the distance and the orientation, the predefined point 305 can be determined, as detailed further herein. In accordance therewith, the virtual circular pattern (e.g., 530) can be determined, as detailed further herein. In some cases, the distance of each of the primary surrounding markers (310-a, 310-b, 310-c, 310-d) from the predefined point 305 and/or the orientation of each of the primary surrounding markers (310-a, 310-b, 310-c, 310-d) relative to the predefined point 305 can be stored in the common identifier 315 of the respective primary surrounding marker, thereby enabling the system to identify, for example, based on data stored in the data repository 220, that the respective primary surrounding marker is a primary surrounding marker.

In some cases, a respective primary surrounding marker (e.g., 310-a, 310-b, 310-c, 310-d) can include a unique identifier, unique to the respective primary surrounding marker. The unique identifier can store the distance of the respective primary surrounding marker from the predefined point 305, and/or the orientation (i.e., angle) of the respective primary surrounding marker relative to the predefined point 305.

The central marker 320 has an identifier 325 that enables the central marker 320 to be identified.

The virtual circular pattern (e.g., 530) can be determined, by system 200, following the identification, by system 200, of any one of the markers (310-a, 310-b, 310-c, 310-d, 320) that is illustrated in Figs. 5A to 5C. To illustrate an example of how the virtual circular pattern (e.g., 530) can be determined, attention is now drawn to Fig. 5B. Fig. 5B is a schematic illustration 510 of the at least part of a landing surface 500 that is illustrated in Fig. 5A, and one example of a (sensor) frame 520, captured by the primary sensor 120, that includes a single primary surrounding marker 310-d that is located on the landing surface 500, in accordance with the presently disclosed subject matter. The shown x-axis and y-axis along the sensor frame are the x-axis and y-axis, respectively, of the primary sensor 120. In accordance with the presently disclosed subject matter, the virtual circular pattern (e.g., 530) is determined based on: (a) an actual size (e.g., in centimeters) of the identified marker (in Fig. 5B, the primary surrounding marker 310-d), (b) a desired radius (e.g., in centimeters) of the virtual circular pattern (e.g., 530) from the predefined point 305 (this data can be stored in the identified marker or in data repository 220) and (c) a distance and an orientation of the identified marker (e.g., primary surrounding marker 310-d), if any, relative to the predefined point 305. The desired radius of the virtual circular pattern (e.g., 530) from the predefined point 305 is determined based on a known planar offset of the primary sensor 120 from the center 134 of the VTOL aircraft 110 and a second distance, if any, between a landing circle on the landing surface above which the center 134 of the VTOL aircraft 110 is to be landed and the predefined point 305. To explain, if the center 134 of the VTOL aircraft 110 is not to be landed at the predefined point 305, the landing point above which the center 134 of the VTOL aircraft 110 is to be landed can be any point on the landing circle. The point on the landing circle at which the center 134 of the VTOL aircraft 110 is landed depends on the orientation of the primary sensor 120 relative to the predefined point 305 upon landing the VTOL aircraft 110, which depends on the orientation of the front end 126 of the VTOL aircraft 110 upon landing the VTOL aircraft 110. In this regard, it is to be noted that the yaw of the VTOL aircraft 110 may not be controlled and may even be non-controllable, such that the center 134 of the VTOL aircraft 110 can be landed above any one of the points on the landing circle. In Fig. 5B, the desired radius of the virtual circular pattern 530 from the predefined point 305 is the distance R of the primary surrounding markers 310 from the predefined point 305, although this does not have to be the case.

The process for determining a virtual circular pattern (e.g., 530) is as follows: Based on the actual size of the identified marker (e.g., primary surrounding marker 310-d) and a number of pixels of at least a part of the identified marker (e.g., a number of pixels of a known side of the identified marker) within the captured (sensor) frame (e.g., 520) (e.g., the number of pixels are counted), the relation between the number of pixels to an actual measurement on the landing surface represented by the number of pixels is determined (after taking into account the orientation of the captured frame (e.g., 520)). This determination can be performed using a known mechanism, for example, ArUco or AprilTag. Based on the known orientation of the identified marker (e.g., primary surrounding marker 310-d) relative to the predefined point 305, a virtual line from the identified marker through the predefined point 305 can be determined. Moreover, based on the known distance of the identified marker (e.g., primary surrounding marker 310-d) relative to the predefined point 305, a virtual point on the virtual line that is the predefined point 305 can be determined. After determining what is the predefined point 305, the virtual circular pattern (e.g., 530) can be determined, since the predefined point 305 represents a center of the virtual circular pattern (e.g., 530), and since the desired radius (in centimeters) of the virtual circular pattern (e.g., 530) is known.

If the center 134 of the VTOL aircraft 110 is to be landed at the predefined point 305, the virtual circular pattern 530 will be at a distance from the predefined point 305 that is identical to the known planar offset of the primary sensor 120 from the center 134 of the VTOL aircraft 110, whether or not this known planar offset is identical (as shown in Fig. 5B) or not identical to the distance of the primary surrounding markers 310 relative to the predefined point 305. However, if the center 134 of the VTOL aircraft 110 is to landed at an offset from the predefined point 305, the virtual circular pattern that is determined surrounds the predefined point 305 at a distance from the predefined point 305 that is different than the known planar offset of the primary sensor 120 from the center 134 of the VTOL aircraft 110.

To explain this, the following example is provided. Primary sensor 120 is mounted under a sensor mounting structure 160, as illustrated in Figs. IE and IF (the views in Figs. IE and IF are from below the VTOL aircraft 110). A payload is mounted at given point 145 under the VTOL aircraft 110, the given point 145 being along the roll axis 138 of the VTOL aircraft 110 but not at the center 134 of the VTOL aircraft 110. In the example, the payload is to be provided at (e.g., on or about) the predefined point 305 upon a landing of the VTOL aircraft 110. In this example, the center 134 of the VTOL aircraft 110 is to be located at a planar distance from the predefined point 305 when the VTOL aircraft 110 is landed, irrespective of a direction of the front end of the VTOL aircraft 110, the planar distance being the distance between the given point 145 and the center 134 of the VTOL aircraft 110. The virtual circular pattern is determined to surround the predefined point 305 with a radius that is identical to the distance of the payload from the primary sensor 120.

It is to be noted that the above example is provided for exemplary purposes only, and that both the primary sensor 120 and the payload can be mounted to the VTOL aircraft 110 at any location on the VTOL aircraft 110. Indeed, either or both of the primary sensor 120 and the pay load can be mounted to the VTOL aircraft 110 such that they protrude outwards of the VTOL aircraft 110 (e.g., are not located under the VTOL aircraft 110). It is to be further noted that the center 134 of the VTOL aircraft 110 can be designated to be at a given distance from the predefined point 305 upon the landing of the VTOL aircraft 110, regardless of an orientation of the front end 126 of the VTOL aircraft 110 upon landing the VTOL aircraft 110, even if no payload is mounted to the VTOL aircraft 110. In some cases, the center 134 of the VTOL aircraft 110 can be designated to be at a given distance from the predefined point 305 upon the landing of the VTOL aircraft 110, regardless of an orientation of the front end 126 of the VTOL aircraft 110 upon landing the VTOL aircraft 110, wherein the yaw of the VTOL aircraft is not controllable, as discussed above.

Upon determining the virtual circular pattern (e.g., 530), system 200 can be configured to determine the sensor anchoring point (e.g., 536) on the virtual circular pattern (e.g., 530), as explained further below, whether the sensor anchoring point (e.g., 536) does not appear in the captured frame (e.g., 520), as shown in Fig. 5B, or the sensor anchoring point (e.g., 536) appears in the captured frame (e.g., 550), as shown in Fig. 5C. Having said that, the sensor anchoring point (e.g., 536) must appear in at least one of the final frames that are captured prior to landing the VTOL aircraft 110 in order to enable the landing of the VTOL aircraft 110.

If: (a) the primary sensor 120 is positioned on the left wing 140 of the VTOL aircraft 110, as illustrated in Figs. 1A to ID, and (b) the orientation of the primary sensor 120 is towards the front end of the VTOL aircraft 110 in parallel to the roll axis 138 (the positive direction of the y-axis of the sensor frame 520 is oriented towards the front end 126 of the VTOL aircraft 110 in parallel to the roll axis while the primary sensor 120 is facing towards the ground), as shown in Fig. IB, then the sensor anchoring point over which the primary sensor 120 is to be located upon a landing of the VTOL aircraft 110 is the highest point 536 on the virtual circular pattern 530 relative to an orientation of the frame 520, as in Fig. 5B (if the sensor anchoring point is in the frame 520, it is at the highest point on the virtual circular pattern 530 in the frame 520). When the part of the virtual circular pattern 530 within the example frame 520 does not include the sensor anchoring point 536, as in Fig. 5B, system 200 can be configured to generate maneuvering commands for maneuvering the VTOL aircraft 110 with the goal of vertically aligning the primary sensor 120 with the sensor anchoring point 536. If a pay load is mounted to the VTOL aircraft 110 at a given point (e.g., 145) that is not along the same axis as the primary sensor 120 (and the payload is to be provided at the predefined point 305 upon landing the VTOL aircraft 110), as in Figs. 1A to ID, the sensor anchoring point over which the primary sensor 120 is to be located upon a landing of the VTOL aircraft 110 is also based on the offset of the primary sensor 120 from the pay load, resulting in the sensor anchoring point being at another point on the virtual circular pattern 530 relative to an orientation of the frame 520, and not the highest point 536 on the virtual circular pattern 530 relative to an orientation of the frame 520, as in Fig. 5B. It is to be noted that in all instances in which the payload is not along the same axis as the primary sensor 120, a determination of the sensor anchoring point 536 is based both on the orientation of the sensor frame relative to the VTOL aircraft and the planar offset of the primary sensor 120 from the payload.

More generally, the point on the virtual circular pattern (e.g., 530) that is determined to be the sensor anchoring point is determined based on the orientation of y- axis of the sensor frame (e.g., 520) relative to the VTOL aircraft 110, as this orientation defines a relation of the axis system of the primary sensor 120 relative to the axis system of the VTOL aircraft 110. For example, if: (a) the primary sensor 120 is positioned on the left wing 140 of the VTOL aircraft 110, as illustrated in Figs. 1A to ID, and (b) the orientation of the primary sensor 120 is away from the center 134 of the VTOL aircraft 110 along the pitch axis (the negative direction of the y-axis of the sensor frame 520 is oriented towards the center 134 of the VTOL aircraft 110 in parallel to the pitch axis while the primary sensor 120 is facing towards the ground), as in Fig. 1C, then the sensor anchoring point on the virtual circular pattern 530 is the rightmost point on the virtual circular pattern 530 relative to the orientation of the frame 520 (if the sensor anchoring point is in the frame 520, it is at the rightmost point on the virtual circular pattern in the frame 520).

As an additional example, if: (a) the primary sensor 120 is positioned on the left wing 140 of the VTOL aircraft 110, as illustrated in Figs. 1A to ID, and (b) the orientation of the primary sensor 120 is towards the back of the VTOL aircraft 110 in parallel to the roll axis 138 (the negative direction of the y-axis of the sensor frame 520 is oriented towards the front end of the VTOL aircraft 110 in parallel to the roll axis while the primary sensor 120 is facing towards the ground), as in Fig. ID, then the sensor anchoring point on the virtual circular pattern 530 is the lowest point on the virtual circular pattern 530 relative to the orientation of the frame 520 (if the sensor anchoring point is in the frame 520, it is at the lowest point on the virtual circular pattern in the frame 520).

As a final example, if: (a) the primary sensor 120 is positioned on the left wing 140 of the VTOL aircraft 110, as illustrated in Figs. 1A to ID, and (b) the orientation of the primary sensor 120 is towards the center 134 of the VTOL aircraft 110, as in Fig. 1A, then the sensor anchoring point of the virtual circular pattern (e.g., 530) along the pitch axis (the positive direction of the y-axis of the sensor frame is oriented towards the center 134 of the VTOL aircraft 110 in parallel to the pitch axis while the primary sensor 120 is facing towards the ground) is the leftmost point on the virtual circular pattern (e.g., 530) relative to the orientation of the frame 520 (if the sensor anchoring point is in the frame 520, it is at the leftmost point on the virtual circular pattern in the frame 520).

Attention is now drawn to Fig. 5C, a schematic illustration 540 of the at least part of a landing surface 500 that is illustrated in Fig. 5A, and one example of a frame 550, captured by the sensor 120, that includes all of the primary surrounding markers (310-a, 310-b, 310-c, 310-d) and the central marker (320) on the landing surface 500, in accordance with the presently disclosed subject matter.

The virtual circular pattern 530 can be determined in the manner described above in Fig. 5B with the exception that in Fig. 5C, the virtual circular pattern 530 can be determined based on the identification of any one of the illustrated markers (310-a, 310-b, 310-c, 310-d, 320). In Fig. 5C, the sensor anchoring point 536 appears in the captured frame 550.

Returning to the sequence of operations 400 in Fig. 4, upon determining the sensor anchoring point (e.g., 536) on the virtual circular pattern (e.g., 530), system 200 can be configured, e.g., using processing circuitry 230, to generate maneuvering commands to maneuver the VTOL aircraft 110 so that the sensor 120 will be substantially vertically aligned with the sensor anchoring point (e.g., 536) upon the landing of the VTOL aircraft 110 (block 412).

System 200 can be configured, e.g., using processing circuitry 230, to continually obtain frames captured by the sensor 120 or another sensor until the landing of the VTOL aircraft 110 (block 404), wherein for each of the obtained frames, a marker is identified (block 408), if readable, and maneuvering commands are generated, based on the identified marker, to control the landing of the VTOL aircraft 110 (block 412). In some cases, a frame may not include a readable marker, for example, if the marker is covered by a shadow. In such cases, system 200 can be configured, e.g., using processing circuitry 230, to continue generating maneuvering commands (which can control movement of the VTOL aircraft 110 in any direction) or abort the landing of the VTOL aircraft 110 (block 432). It is to be noted in this regard that if the frame includes a marker that is covered by a shadow or anything else that conceals the marker, making the marker unreadable, but the frame also includes an additional marker that is readable, system 200 can be configured to generate maneuvering commands for controlling the landing of the VTOL aircraft 110 based on the additional marker that is readable.

In some cases, following the identification of a marker in a given frame (e.g., 520) that enables the determination of a virtual circular pattern (e.g., 530), the VTOL aircraft 110 may capture a successive frame in which a marker that enables the determination of the virtual circular pattern cannot be captured due to movement of the VTOL aircraft 110, e.g., resulting from wind gusts. To compensate for this, one or more inner gust markers (e.g., 330) and/or one or more outer gust markers (e.g., 340) can be included in the pattern of markers (e.g., 300) to enable the system 200 to maneuver the VTOL aircraft 110 back towards one of the primary surrounding markers 310 following a wind gust. An inner gust marker or an outer gust marker (more generally, a gust marker) can be captured by primary sensor 120 or another sensor, different than the primary sensor 120, that is mounted to the VTOL aircraft 110. For example, the primary sensor 120 can be an optical sensor, and the sensor for capturing the gust markers can be an acoustic sensor that detects movement of the VTOL aircraft 110 over gust markers. Following the detection of a movement of the VTOL aircraft 110 over a respective gust marker, by a sensor (e.g., an acoustic sensor), system 200 can be configured to generate maneuvering commands to maneuver the VTOL aircraft 110 back towards the primary surrounding markers 310.

It is to be noted generally that, in the present disclosure, the VTOL aircraft 110 can be landed with the primary sensor 120 being offset from the predefined point 305, and wherein the primary sensor 120 is capable of being at any orientation relative to the predefined point 305 upon the landing of the VTOL aircraft 110. In some cases, a yaw of the VTOL aircraft 110 is not controllable. For example, the VTOL aircraft 110 can be designed such that a front end 126 of the VTOL aircraft 110 always opposes the direction of the wind, and, as indicated above, in some cases, the VTOL aircraft 110 cannot actively change the yaw angle, which is passively determined in accordance with the direction of the wind (feathering). It is to be noted that, with reference to Fig. 4, some of the blocks can be integrated into a consolidated block or can be broken down to a few blocks and/or other blocks may be added. Furthermore, in some cases, the blocks can be performed in a different order than described herein. It is to be further noted that some of the blocks are optional. It should be also noted that whilst the flow diagrams are described also with reference to the system elements that realizes them, this is by no means binding, and the blocks can be performed by elements other than those described herein.

It is to be understood that the presently disclosed subject matter is not limited in its application to the details set forth in the description contained herein or illustrated in the drawings. The presently disclosed subject matter is capable of other embodiments and of being practiced and carried out in various ways. Hence, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for designing other structures, methods, and systems for carrying out the several purposes of the present presently disclosed subject matter.

It will also be understood that the system according to the presently disclosed subject matter can be implemented, at least partly, as a suitably programmed computer. Likewise, the presently disclosed subject matter contemplates a computer program being readable by a computer for executing the disclosed method. The presently disclosed subject matter further contemplates a machine-readable memory tangibly embodying a program of instructions executable by the machine for executing the disclosed method.