Point take-off and landing of unmanned flying objects

Point take-off and landing systems for an unmanned flying object. In one embodiment, the flying object is guided along a flight trajectory and approaches a landing body such that a latching element, coupled with a suspension cable suspended from the flying body, latches with a receiving latch, coupled with an extendable retractable beam projecting horizontally from a landing body side surface. A cable release/retraction mechanism engages and then releases/retracts the suspension cable. The beam is as maneuvered to haul the flying object onto a landing surface. In another embodiment, the flying object is guided along a flight trajectory and approaches a landing body such that a latching element, coupled with a suspension cable suspended from the flying body, latches with a receiving cable, supported by cable supports projecting vertically from a landing body top surface. A cable release/retraction mechanism releases/retracts the suspension cable, hauling the flying object onto the landing surface.

This application is a U.S. national phase of International Application No. PCT/IL2013/050351 filed on Apr. 23, 2013, which claims benefit of Israel Application Serial No 219836, filed May 16, 2012, both of which are incorporated by reference herein in their entirety.

FIELD OF THE DISCLOSED TECHNIQUE

The disclosed technique relates to systems and methods for point take-off and landing (PTOL) of unmanned flying objects, such as unmanned aerial vehicles (UAVs), onto a confined landing surface associated with a landing body.

BACKGROUND OF THE DISCLOSED TECHNIQUE

Point take-off and landing (PTOL) relates to the capabilities of unmanned aerial vehicles (UAVs) and other aircrafts to perform take-off and landing operations without a runway at a confined location. In today's high spending UAV military market, there is a lack of good solutions for enabling PTOL of UAVs. One specific example is the recovery of large-wingspan fixed-wing UAVs onto moving vehicles on land or on water. The large wingspans of these UAVs complicates the ability to land onto a ship or similar aquatic vessel, which may be subject to large amplitude and rapid angular movements along its roll, pitch and yaw axes. The difficulty for safe UAV landing may be further exacerbated by the ship's masts and antennas and by the turbulence behind the ship superstructure. Besides the lack of a runway, PTOL of a UAV onto (or from) a land vehicle may also be complicated by the presence of obstacles in the vicinity of the vehicle, by strong winds, and by darkness or low-visibility weather conditions.

The need for UAV recovery onto a ship has a long history. In 1985, Floyd Kennedy of the AIL Corporation discussed the need for fleet-integral UAVs to provide Airborne Early Warning (AEW) to U.S. Navy non-aviation task forces. The solution was observed to lie with fixed-wing UAVs due to their endurance capabilities, raising issues for point landing of such UAVs onto small ships (i.e., non-aircraft carriers), such as the concern that their long wings may interfere with the ship deck elements. Especially noteworthy is the U.S. Congress defined requirement for “Endurance Category” UAVs (i.e., which are capable of remaining airborne for long durations) for U.S. Navy ships, in the first “UAV Masterplan” of 1988, although no such system appears to have been deployed as of yet. One problem is that fixed-wing UAVs and other similar flying objects cannot hover like a helicopter while connecting to a ship's cable, so the U.S. Navy's RAST (Recovery Assist & Transfer) system solution for helicopters cannot be used. Additionally there is a need to cope with turbulence behind the ship's superstructure, wind-over-deck from all directions and at various intensities, and darkness or low-visibility weather conditions.

U.S. Pat. No. 7,219,856 to Watts, entitled “UAV recovery system” discloses an embodiment where a UAV system is coupled to the deck of a sea faring vessel. The UAV capture system includes a single arresting line that is supported by a stanchion, which may be disposed on a rotatable boom. The UAV hooks onto the line and is abruptly stopped in flight and once stopped it appears to be left hanging, which may cause damage to the UAV.

Australian Patent Application No. 2009200804 to Kariv, entitled “An unmanned aerial vehicle launching and landing system” discloses an embodiment relating to a system for landing UAVs. The system comprises an arm based structure and an axis means installed along the arm of the structure, enabling the arm to move around it. The arm is propelled into rotational motion around the axis from the instant that the UAV connects to landing arm. It appears that the rotational momentum of UAVs, especially heavier ones, may apply a taxing force onto the rotational axis.

SUMMARY OF THE DISCLOSED TECHNIQUE

In accordance with one aspect of the disclosed technique, there is thus provided a PTOL system for an unmanned flying object. The PTOL system includes a suspension cable, a latching element, a beam, a receiving latch, and a cable release/retraction mechanism. The suspension cable is suspended from the flying object. The latching element is coupled with the suspension cable. The beam projects horizontally from a side surface of a landing body, and is extendable and retractable. The receiving latch is coupled with the beam. The cable release/retraction mechanism is operative for releasing and/or retracting the suspension cable or a retraction cable coupled with the latching element. The flying object is guided along at least one flight trajectory, the flying object approaching the landing body such that the latching element latches with the receiving latch and the cable release/retraction mechanism engages the suspension cable, following which the cable release/retraction mechanism releases and/or retracts the suspension cable and the beam is maneuvered to haul the flying object onto a landing surface at the landing body. The beam may be stabilized, to minimize relative motion of the beam resulting from motion of the landing body. The landing body may be an aquatic vessel. The beam may be pivotable about at least one axis. The landing surface may be pivotable about at least one axis. The beam may be inclined at an angle to facilitate the latching of the latching element with the receiving latch. The PTOL system may further include an elevator, operative for transporting the flying object within the landing body. The landing body may include a stowage compartment, operative for stowing away the flying object after landing. The landing body may include at least one door, through which the beam is projectable, where the beam is retractable into the landing body, and where at least one door is closed while the beam projects outward from the landing body.

In accordance with another aspect of the disclosed technique, there is thus provided a point take-off and landing (PTOL) system for an unmanned flying object. The PTOL system includes a suspension cable, a latching element, at least one cable support, a receiving cable, and a cable release/retraction mechanism. The suspension cable is suspended from the flying object. The latching element is coupled with the suspension cable. The cable support projects vertically from a top surface of the landing body such that the flying object can maneuver beyond any obstacles in the vicinity of the landing body. The receiving cable is supported by the cable support. The cable release/retraction mechanism is coupled with the suspension cable or receiving cable, and is operative for releasing and/or retracting the suspension cable or receiving cable. The flying object is guided along at least one flight trajectory, the flying object approaching the landing body such that the latching element latches with the receiving cable, following which the cable release/retraction mechanism releases and/or retracts the receiving cable, hauling the flying object onto a landing surface at the landing body. The cable support may include two cable supports projecting vertically from a top surface of the landing body, where the receiving cable is coupled in between the two cable supports. The two cable supports may be aligned in a parallel configuration, a V-form configuration, or a canted-V form configuration. The cable support may be inclined at an angle to facilitate the latching of the latching element with the receiving cable. A receiving latch may be coupled with the receiving cable, for latching with the latching element. The cable release/retraction mechanism may include at least one winch. The cable release/retraction mechanism may include a first winch situated proximal to the cable support and coupled with the receiving cable, and a second winch situated remotely from the cable support and coupled with the receiving cable, where the first winch and second winch are operative to simultaneously retract the receiving cable to pull the flying object down and forwards while slowing down the flying object. The cable support may be extendable and retractable. The flying object may deploy an aerodynamic lift/drag mechanism to facilitate hovering at a particular height or to facilitate turning around. The retraction of the receiving cable may cause to flying object to turn around with respect to an initial trajectory, such that the flying object is facing an opposite direction from the initial trajectory upon landing. The receiving cable may pull the flying object backwards, without the flying object turning around with respect to an initial trajectory, such that the flying object is facing the same direction as the initial trajectory upon landing. The flying object may approach the landing body in a downwind direction. The flying object may be pulled forward and down onto the landing surface, without the flying object having turned around with respect to an initial trajectory, such that the flying object is facing the same direction as the initial trajectory upon landing. The landing body may be: a land vehicle, a truck, a military vehicle, a High Mobility Multipurpose Wheeled Vehicle (HMMWV), an armored personnel carrier, an aquatic vessel, a boat, a submarine, an aircraft, a moving platform, and/or a stationary platform. The flying object may be: unmanned aerial vehicle (UAV), a piloted aircraft, or a package. The flying object may follow at least one flight trajectory in accordance with a selected landing scenario. The flight trajectory may include: approaching the landing body upwind; flying along a direction that is transverse to the wind direction or to the motion of the landing body; repetitively flying back and forth transverse to the wind direction or to the motion of the landing body; ascending and then gradually descending; repetitively ascending and descending; and/or a flight maneuver that extends the flight duration of the flying object, such that wind drift results in a lag between the flying object and landing body that enables effective hauling down of the flying object onto the landing body by the receiving cable. The selected landing scenario may be based on: parameters at the vicinity of the landing body; parameters of the flying object; parameters of the landing body; and/or current operational characteristics of system components. The PTOL system may include at least one measuring instrument, operative for acquiring at least one of the parameters. The PTOL system may further include a control unit, operative for controlling the flying object and/or landing system components.

In accordance with a further aspect of the disclosed technique, there is thus provided a method for point landing of an unmanned flying object. The method includes the procedures of: acquiring parameters at the vicinity of a landing body, including at least the wind speed and the wind direction thereat; acquiring parameters of the flying object, including at least the speed, direction and altitude thereof; and acquiring parameters of the landing body, including at least the speed, direction and altitude thereof. The method further includes the procedures of: obtaining current operational characteristics of landing system components of the landing body; generating potential landing scenarios in accordance with the acquired parameters and current operational characteristics; and selecting a landing scenario to implement. The method further includes the procedure of executing the selected landing scenario and guiding the flying object along at least one flight trajectory in accordance with the selected landing scenario, by managing the flying object flight controls and selectively activating and maneuvering the landing system components, including: directing the flying object to approach the landing body such that a latching element suspended from the flying object latches onto a receiving cable coupled with the landing body; and releasing and/or retracting the receiving cable with a cable release/retraction mechanism, hauling the flying object onto a landing surface at the landing body. At least one of the procedures may be automated. The flight trajectory may include: approaching the landing body upwind; flying along a direction that is transverse to the wind direction or to the motion of the landing body; repetitively flying back and forth transverse to the wind direction or to the motion of the landing body; ascending and then gradually descending; repetitively ascending and descending; and/or a flight maneuver that extends the flight duration of the flying object, such that wind drift results in a lag between the flying object and landing body that enables effective hauling down of the flying object onto the landing body by the receiving cable. The landing scenario may include a following operation of the flying object: deployment of aerodynamic lift/drag augmentation mechanisms; hovering at a particular altitude; initiating a turn; cutting off engine power; turning around with respect to an initial trajectory, by the retraction of the receiving cable, such that the flying object is facing an opposite direction from the initial trajectory upon landing; being pulled backwards by the receiving cable, without turning around with respect to an initial trajectory, such that the flying object is facing the same direction as the initial trajectory upon landing; and being pulled forward and down onto the landing surface, without the flying object having turned around with respect to an initial trajectory, such that the flying object is facing the same direction as the initial trajectory upon landing. A control unit may control the flying object, the landing body and/or the landing system components.

In accordance with yet another aspect of the disclosed technique, there is thus provided a PTOL system for sequential landing of unmanned flying objects. The PTOL system includes a suspension cable, a latching element, a railway, and a latching mechanism. The suspension cable is suspended from each of the flying objects. The latching element is coupled with the suspension cable. The railway includes a trap segment and a touchdown region. The latching mechanism is operative for engaging with the latching element. One of the flying objects approaches the railway along a landing approach trajectory toward the trap segment, such that the latching element latches with the latching mechanism, which then pulls the suspension cable down and forwards, hauling down the flying object onto the railway within the touchdown region. The flying object may include a global positioning system (GPS), operative for directing the flying object toward the trap segment of the railway. The latching mechanism may include a plurality of clasps rotating sequentially along a moving chain arranged in a track situated underneath the railway. The railway may include a triggering element, operative for triggering the activation of the latching mechanism. The trap segment may include two rail portions of the railway, each of which extends outward laterally in a V-shape. The flying object may be a UAV. The railway may further include a maintenance region, at which the flying object undergoes at least one maintenance or flight preparation operation. The railway may further include a launching region, at which the flying object is launched from. The railway may be mounted onto a landing body, such as: an aquatic vessel, a land vehicle, a stationary platform, and/or a moving platform.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The disclosed technique overcomes the disadvantages of the prior art by providing systems and methods for point take-off and landing (PTOL) of an unmanned flying object, such as an unmanned aerial vehicle (UAV), onto/from a confined landing surface, without a runway. The landing surface is associated with a landing body, such as a land vehicle or an aquatic vessel, which may be in motion during the landing or take-off operations. The disclosed technique is especially useful for PTOL of a UAV during strong winds. The disclosed technique is particularly applicable to the landing/take-off of large-wingspan fixed-wing UAVs onto/from a ship.

The term “flying object”, and any variations thereof, as used herein, refers to any type of unmanned object or vehicle, capable of controlled flight maneuvering along an aerial trajectory during a take-off or landing, including but not limited to: a UAV, a parachuted parcel, and the like.

The term “latching element”, as used herein, refers to any type of element or structure capable of latching onto or otherwise engaging with a receiving latch, including but not limited to: a hook, a clip, a clasp, a fastener, a magnet, and the like.

The term “receiving latch”, as used herein, refers to any type of element or structure capable of being latched onto or otherwise engaged by a latching element, including but not limited to; a cable, a cable loop, a magnet, a wire, and the like.

The terms “rod” and “cable support”, and any variations thereof, are used herein interchangeably to refer to any type of structure for supporting a receiving cable at a certain location, height, and orientation relative to the landing body, to enable the latching or engagement of the hook with the receiving cable or receiving latch. For example, the rod may be: a post, a pole, a tree, and the like.

The term “cable release/retraction mechanism”, and any variations thereof, as used herein, refers to any type of device or mechanism operative for retracting and releasing (e.g., winding and unwinding) the cable at a particular speed, and/or otherwise controlling the tension of a cable, as desired. For example, the cable release/retraction mechanism may be: a winch, such as a mechanical, electric, hydraulic, pneumatic, or manually-operated winch; a griphoist; a ratchet and pawl assembly; and the like. Correspondingly, the terms “retract” and “release”, and any variations thereof, as used herein, refer to the operations of winding/reeling in the cable, and unwinding/reeling out the cable, respectively.

Reference is now made toFIG. 1A, which is a schematic illustration of a UAV landing system, generally referenced100, with a UAV, referenced102, approaching a desired landing point, constructed and operative in accordance with an embodiment of the disclosed technique. UAV102flies overhead and towards a landing surface130on a ship120. UAV landing system100generally includes a UAV102and a landing component150. UAV102includes a suspension cable104and a hook106. Suspension cable104is coupled with hook106, and is suspended from UAV102in preparation for landing. Landing component150includes a landing surface130, a rod110, and a receiving latch108. Receiving latch108is situated at the end of rod110, which is mounted onto landing surface130.

Reference is now made toFIG. 1B, which is a schematic illustration of a subsequent stage of the UAV landing system ofFIG. 1A, in which the hook latches onto the receiving latch. As UAV102flies above landing component150, hook106latches onto receiving latch108, such that they are securely engaged with one another. Hook106represents an exemplary latching element, while other types of latching elements may be utilized instead.

Reference is now made toFIG. 1C, which is a schematic illustration of a subsequent stage of the UAV landing system ofFIG. 1A, in which the UAV is guided toward the landing surface along a desired landing path. Once hook106latches onto receiving latch108, a cable release/retraction mechanism (not shown) is activated, enabling UAV102to continue its flight path while being guided towards landing surface130along a landing path132. Landing path132is depicted inFIG. 1Cas substantially semi-elliptical in shape, however alternative landing path shapes or configurations are also applicable. It is also appreciated that the UAV may follow the same landing path, or similar landing path segments, multiple times, such as by repetitively circling around landing surface130before landing. During UAV102landing, landing system100takes into account the ship's motion and the current wind conditions, and may direct UAV102to maneuver a certain way and/or to change aerodynamic parameters, such as by deploying flaps or changing engine power settings, in order to effectively guide UAV102onto landing surface130. It is understood that landing surface130may alternatively be on a platform other than a ship, for example: a land vehicle (e.g., a truck, or a military vehicle such as a High Mobility Multipurpose Wheeled Vehicle (HMMWV) or an armored personnel carrier), an alternative aquatic vessel (e.g., a boat or a submarine), another aircraft, a stationary location on the ground, and the like. It is also understood that the disclosed technique is also applicable for landing other types of flying objects (besides a UAV), such as a piloted aircraft, or a package, parcel, or other cargo to be delivered. For example, a small aircraft carrying a parcel approaches a landing surface130with a landing component150(as shown inFIG. 1A), where the parcel includes a suspension cable with a hook (analogous to suspension cable104and hook106). When the aircraft is within sufficient proximity of landing surface130, the hook latches onto the receiving latch, such that the parcel detaches from the aircraft and is then guided along a landing path onto landing surface130(following the same landing process as described hereinabove for UAV102).

UAV landing system100may further include a tracking and guidance mechanism, a navigation system, a global positioning system, closed-loop cameras, night vision instruments, and other forms of tracking and communication and control systems known in the art, in order to facilitate the landing (or launching) of UAV102. UAV landing system100may be at least partially automated, and/or may be operated by a human operator (e.g., via relevant controllers, interfaces and/or input devices). Components of such tracking/communication/control systems can reside on the landing surface130(e.g., on ship120), on the flying object (e.g., on UAV102), and/or at a remote or nearby location (e.g., a control station).

Reference is now made toFIG. 2, which is a close up schematic illustration of the landing system100ofFIGS. 1A-1C, illustrating cable release/retraction mechanism components. The cable release/retraction mechanism of landing system100includes a pulley217and winch218at the landing surface130, and a pulley227and winch228at the UAV102. Landing system100further includes a cable204, which is spooled around winch218and threaded around pulley217and forms a loop208. Loop208embodies an exemplary receiving latch108(FIG. 1A). Suspension cable104of UAV102is also spooled around winch228and threaded around pulley227. Referring toFIG. 2, UAV102approaches landing surface130in such a manner as to enable hook106to latch into loop208. It is noted, that hook106can generally latch onto a loop208more easily as compared to other forms of receiving latches, which may require greater flight accuracy and/or manual intervention to properly position the hook with respect to the receiving latch to ensure that the latching takes place. Cable support110may be inclined at a particular angle (e.g., approximately 20° azimuth), and or otherwise configured (e.g., having a particular size and shape), in order to facilitate the latching of hook106onto loop208, by providing a larger tolerance for the UAV approach trajectory that would result in successful latching. Once hook106latches onto loop208, winch228is activated to release the required cable length, allowing UAV102to continue flying smoothly (e.g., without resulting in an abrupt tug) while now being attached to landing component150. The latching of loop208onto hook106triggers at least one winch218,228to release additional cable204and104, respectively, thereby further providing cable slack to enable UAV102to continue along its current flight path. Winches228and218may be controlled by at least one processor, which may be situated at a remote location, on UAV102, and/or on landing component150. Gradually, cables104and204are released at a slower rate such that a gradual pulling force is applied to UAV102. Eventually winches218and228begin to retract cables104and204such that UAV102is hauled down onto landing surface130. Suspension cable104and hook106may then be fully retracted into UAV102(e.g., via winch218), in order to avoid interfering with system components. After landing, UAV102may be secured in place by cable104, to prevent being inadvertently repositioned or damaged due to strong winds. It is understood that landing system100may employ either or both of winches218and228when retracting or releasing cable104and/or cable204. Pulleys217and227facilitate smooth retraction and release of cables104and204via winches218and228. It is understood that a landing system100may generally include any number of pulleys and winches in any suitable arrangement or configuration, in order to facilitate the retraction and release of cables104and204when landing UAV102. Landing system100may also include at least one controller (not shown) for controlling UAV102flight operations and/or for controlling the activation/maneuvering of the landing system components (e.g., controlling operation of the cable release/retraction mechanism).

It is appreciated that the landing system of the disclosed technique enables UAV landing to be implemented in adverse weather, such as during strong winds (e.g., 50-70 knots). For example, when landing a UAV in a strong wind, the UAV is initially directed to fly upwind over the landing surface. The UAV continues forward beyond the location of the winch, and the UAV latching element latches onto the receiving latch. The UAV then gradually ascends while decreasing velocity. The UAV may reduce engine power and/or deploy aerial decelerators to assist in decreasing velocity. The UAV drifts backwards (downwind) due to the wind while maintaining a minimum flight speed, and eventually passes back over the landing system location. Subsequently, the UAV can be pulled down and forwards onto the landing surface via retraction of the receiving cable by the winch.

Reference is now made toFIG. 3, which is a perspective view schematic illustration of a UAV landing system, generally referenced300, for landing a UAV in an aquatic environment, constructed and operative in accordance with another embodiment of the disclosed technique. Landing system300includes a UAV302with a suspension cable304and a hook306. Landing system300further includes a ship320that includes a receiving latch308, a beam310, a receiving cable307, a winch (not shown), a landing plate330and an elevator360. Beam310is a telescopically extendable and retractable rod or pole which projects outwards substantially horizontally from ship320(e.g., being coupled perpendicular to another rod that extends vertically above the deck of ship320, as shown inFIG. 3). Beam310may be pivotable about at least one axis (e.g., azimuth and/or elevation). Landing plate330is coupled to beam310, and may also be pivotable about at least one axis (e.g., azimuth and/or elevation) independent of beam310. Receiving latch308is initially coupled at one end of beam310. UAV302may include a parachute340and/or alternative aerodynamic or flight control mechanisms, in order to facilitate maneuvering of UAV302(e.g., for lowering the stall speed) in preparation for landing.

UAV302may follow a flight path332when approaching ship302, to maneuver properly in preparation for landing. When UAV302passes over beam310with suspension cable304hanging downwards, hook306engages with and latches onto receiving latch308. The latching may be facilitated by the size/shape/orientation of beam310. For example, beam310may be inclined forward at a particular angle (e.g., approximately 20° azimuth), such that suspension cable304is guided by the beam310to direct hook306toward receiving latch308. In another example, receiving latch308may be disposed separately from beam310, such as being coupled with a second auxiliary beam (not shown) that projects outward from ship320adjacent to the main beam310, while a receiving cable is coupled with receiving latch208and an inclined main beam310, thus facilitating the latching of hook306with receiving latch208and/or the receiving cable. After the latching takes place, cable304may be reeled inside UAV302by a UAV winch (not shown), in order to avoid subsequent interference with other components of landing system300. It is noted that since beam310projects outward over the water, the latching between hook306and receiving latch308occurs above the water, rather than over the body of ship320, thereby providing sufficient clearance for the wingspan of UAV302while avoiding potential equipment damage and potential injury to the occupants of ship320.

After the latching between hook306and receiving latch308, beam310may telescopically retract (e.g., until point353), in order to guide UAV302towards and onto landing plate330. Landing plate330may be pivoted (e.g., horizontally and/or vertically) about pivot point352, for adjusting landing plate330into a suitable position for contact with UAV302. Beam310may also be pivoted horizontally about pivot point354. Beam310may be telescopically extendable and retractable between points353and354, enabling optimal placement of landing plate330for collecting UAV302. Similarly, the vertical rod coupled to beam310(i.e., below point354) may be retractable or extendable, allowing for the optimal placement of landing plate330above the water during the collection of UAV302, and for lowering landing plate330together with UAV302onto the deck of ship320. Once UAV302is positioned onto landing plate330, UAV102may be secured in place (e.g., using cable304and/or other suitable means). Landing plate330is sized, shaped and/or configured to enable the collection and subsequent securing of UAV302(e.g., with securing latches). Landing plate330may include slots or notches to enable passage of cable304and/or cable307. Subsequently, UAV302may undergo any necessary operations, such as refueling or repairs, or may be stowed away.

Beam310is substantially stabilized (prevented from substantial motion along pitch, roll, or yaw axes), in order to ensure stable latching of UAV302and its subsequent positioning onto landing plate330, despite potentially large amplitude and rapid angular movements (e.g., rolling, heaving, swaying) experienced by ship320during its voyage. Beam310may also be used for the launching or takeoff of UAV302from ship320, by incorporating suitable launching mechanisms, such as rails, booster bottles, and the like (for example railway1010ofFIGS. 10A and 10B, discussed hereinbelow).

Elevator360may be used to stow the landed UAV302within the body of ship320(e.g., to provide concealment and/or protection from the environment). Once UAV302has touched down onto landing plate330, landing plate330may be maneuvered and positioned above elevator360. Elevator360then descends into the body of ship320, lowering UAV302, landing plate330, and other components of landing system300, such as beam310, down into ship320. After being lowered, UAV302may be stowed away at a secure location within ship320. Elevator door362may then be closed, restoring the continuity of the body of ship320.

Reference is now made toFIGS. 4A, 4B and 4C.FIG. 4Ais a perspective view schematic illustration of a ship with a UAV stowage compartment, constructed and operative in accordance with an embodiment of the disclosed technique.FIG. 4Bis a schematic illustration of an initial stage of a UAV landing system, generally referenced400, for landing a UAV onto the ship ofFIG. 4A.FIG. 4Cis a schematic illustration of a subsequent stage of the UAV landing system ofFIG. 4B, in which the landing components are deployed. Ship420includes an interior stowage compartment460, and a large main side door462and a small corner door463(seen inFIGS. 4B and 4C) that open into stowage compartment460. UAV landing system400of ship420includes a landing plate430and beam410, which are analogous to landing plate330and beam310of UAV landing system300(FIG. 3). Beam410projects horizontally outward from the side of ship420, allowing for landing and subsequent passage of a UAV through side doors462,462and into stowage compartment460. Such a capability may be particularly useful for ships having a high wall surrounding the ship deck, which would cause difficulties for transporting a UAV onto the ship deck after landing. Ship420may be a stealth ship, which attempts to be resistant to radar detection by having an exterior shape and surface that minimizes reflected radar signals, such as being composed of a material that substantially absorbs or reflects radar signals. Thus, it is desirable to maintain the continuity of the exterior surface of ship420as often as possible, to minimize susceptibility to radar detection as well as to provide protection from the environment. Accordingly, main door462is generally maintained in a closed position.

Referring toFIG. 4B, in preparation for landing UAV402, doors462and463are opened, and beam410and landing plate430begin to emerge from the side of ship420(e.g., by pivoting outwards). Referring toFIG. 4C, beam410and landing plate430are fully deployed with beam410projecting outward horizontally from the side of ship420, allowing for main door462to be closed while only corner door463remains opened, to substantially restore the exterior continuity of ship420. It is noted that beam410generally extends outward a significant distance away from ship420, which allows UAV402to latch onto beam410far away from ship420, minimizing the risk of damage to ship420and UAV402and avoiding potential injury to the occupants of ship420. Beam410may be automatically or manually stabilized using a stabilization mechanism, to minimize motion of beam410as a result of the movements (e.g., pitch, yaw, roll) of ship420. Beam410may also be raised to ensure that landing plate430is maintained at a sufficient height above the water surface.

Reference is now made toFIGS. 4D, 4E and 4F.FIG. 4Dis a schematic illustration of a subsequent stage of the UAV landing system ofFIG. 4B, in which the latching has taken place.FIG. 4Eis a schematic illustration of a subsequent stage of the UAV landing system ofFIG. 4B, in which the UAV is guided onto the landing plate,FIG. 4Fis a schematic illustration of the ship ofFIG. 4A, illustrating a landed UAV entering the stowage compartment. As UAV402approaches ship420for landing, the latching element (not shown) coupled to UAV402engages a receiving latch on beam410and latches thereto (FIG. 4D). Beam410may be inclined forward at a particular angle, in order to facilitate the latching of the latching element with the receiving latch. Subsequently, UAV402is guided onto landing plate430(FIG. 4E), and is then conveyed into stowage compartment460(FIG. 4F), via suitable retraction and maneuvering of beam410and landing plate430. UAV402may be properly adjusted and aligned in order to enable UAV402to pass through the opening of door462and to fit inside stowage compartment460. After UAV402has entered stowage compartment460, doors462and463may be closed to restore continuity to the exterior of ship420. UAV402may be stowed away as soon as possible after landing, to minimize susceptibility of ship420to radar detection.

Reference is now made toFIGS. 4G and 4H.FIG. 4Gis a schematic illustration of the ship ofFIG. 4A, illustrating a UAV exiting the stowage compartment in preparation for a launch.FIG. 4His a schematic illustration of the ship ofFIG. 4A, illustrating a UAV launching. To enable UAV402to exit stowage compartment460in preparation for launch (take-off), doors462and463are opened and then beam410is extended, pivoted and maneuvered from within stowage compartment until it projects outwards from the side of ship420, with UAV402positioned on landing plate430. As soon as UAV402has fully exited stowage compartment460, side door462may be closed, leaving only corner door463open for beam410to pass through. Beam410is extended outwards such that landing plate430and UAV402are positioned above the water surface beyond ship420. Beam410and/or landing plate430may also be maneuvered (e.g., rotated) such as to position UAV402at a desired elevation angle and a desired azimuth angle (e.g., accounting for current wind conditions) to facilitate its launching. Prior to launch, UAV402may start its engine and undergo any requisite pre-flight system checks. Once UAV402has launched, side door462re-opens (if necessary), beam410is retracted and maneuvered back into stowage compartment460, and then doors462and463are closed again. It is noted that a different flying object (i.e., other than a UAV) may also be adapted and/or maneuvered as necessary to enable it to be transferred into and out of stowage compartment460.

Reference is now made toFIG. 5A, which is a perspective view schematic illustration of a UAV landing system, generally referenced500, mounted on a vehicle, for landing a UAV in proximity to high surrounding obstacles, constructed and operative in accordance with another embodiment of the disclosed technique. UAV landing system500generally includes a UAV502with a suspension cable540and a hook506, and a vehicle520which includes two rods510A and510B, a receiving cable508, pulleys517A,517B and517C, a double-drum winch518, and a wire bed530. Vehicle520may be any type of land vehicle or mobile platform suitable for carrying the necessary equipment associated with landing system500, such as for example a truck. Rods510A and510B project substantially vertically from vehicle520, such that the apex of rods510A,510B is at least substantially higher than the apex of obstacles, such as trees560, located in the vicinity of vehicle520. Rods510A and510B are optionally telescopically extendable/retractable and pivotable. Rods510A and510B may be anchored to the ground or a nearby fixed structure for support (e.g., via guy-wires). Cable508forms a loop between winch518and the upper ends of rods510A and510B. Cable508is threaded around pulleys517A,517B and double pulley517C, enabling the release and retraction of cable508along pulleys517A,517B and517C via winch518. It is understood thatFIG. 5Adepicts an exemplary cable and pulley configuration, and landing system500may include an alternative number of pulleys and/or pulleys that are arranged in an alternative configuration with respect to the receiving cable. UAV502is shown approaching vehicle520inFIG. 5A, while flying in a downwind direction. It is appreciated that vehicle520and the components of UAV landing system500are positioned and oriented in accordance with the wind direction, and may be adjusted as necessary if the wind direction changes prior to the UAV landing.

Reference is now made toFIG. 5B, which is a schematic illustration of a subsequent stage of the landing system ofFIG. 5A, in which the latching has taken place. As UAV502passes over rods510A and510B, hook506latches onto receiving cable508. Winch518implements controlled cable release/retraction to ensure that UAV continues downwind along its flight trajectory after the latching has occurred.

Reference is now made toFIG. 5C, which is a schematic illustration of a subsequent stage of the landing system ofFIG. 5A, in which the UAV is being pulled backwards. Following the latching of hook506onto cable508and the release of cable508via winch518(FIG.5B), the forward motion of UAV502is eventually halted and then UAV502is gradually pulled backwards upwind by the retraction of cable508via winch518. A parachute540(or other suitable mechanism) is optionally deployed from UAV502to facilitate the turning around, as well as to enable UAV502to hover at a desired altitude under controlled tension from cable508. The pulling force applied by retracting cable508(optionally with parachute540) causes UAV502to turn around (e.g., executing an approximately 180° turn) so that UAV502eventually faces upwind as it is being pulled by cable508.

Reference is now made toFIG. 5D, which is a schematic illustration of a subsequent stage of the landing system ofFIG. 5A, in which the UAV has come to rest between the cable supports. UAV502is pulled backwards (upwind) by the retraction of cable508until UAV502is eventually suspended and comes to rest in between rods510A and510B.

Reference is now made toFIG. 5E, which is a schematic illustration of a subsequent stage of the landing system ofFIG. 5A, in which the UAV has been lowered onto the landing surface. Once UAV502is in a suspended position in between rods510A,510B (FIG. 5D), rods510A and510B are retracted and, if necessary, cable508is slightly released, thereby lowering and positioning UAV502onto wire bed530located on the top of vehicle520. The use of wire bed530is optional, and UAV502may alternatively be positioned directly onto a surface of vehicle520, or onto an alternative landing platform.

It is appreciated that landing system500enables the necessary landing operations for UAV502(e.g., latching, halting forward motion, hovering and turning around, hauling in) to take place entirely above any obstacles (e.g., entirely above trees560), avoiding interference of the UAV landing by the obstacles.

Reference is now made toFIG. 5F, which is a schematic illustration of a UAV landing system, generally referenced540, mounted on a submarine, for landing a UAV in an aquatic environment, constructed and operative in accordance with a further embodiment of the disclosed technique. UAV landing system540is generally analogous to landing system500(FIGS. 5A-5E), but instead of being mounted onto a land vehicle520, landing system540is mounted onto a submarine542, to enable point landing of a UAV502in an aquatic environment (e.g., a sea or ocean), without the UAV coming into contact with the water, which could result in damage to UAV equipment and components and pose a safety hazard during subsequent flights. Submarine542may be partially or fully submerged beneath the water surface550, while rods510A and510B extend upwards from submarine542substantially above the water surface550, to enable the landing operations for UAV502(e.g., latching and cable release/retraction operations) to take place entirely above water surface550. Accordingly, the water surface550of the sea or ocean can be considered an obstacle, similar to the trees560ofFIGS. 5A-5E, from which it is desirable to avoid interference during the UAV landing. After UAV502has landed using landing system540it may be conveyed into submarine542. It is understood that while rods510A and510B are depicted as being aligned substantially parallel to one another inFIGS. 5A-5F, rods510A and510B may alternatively by disposed in an alternative suitable alignment, such as: a V-form, a canted V-form, and the like, that still allows for the implementation of the aforementioned landing process.

Reference is now made toFIG. 6A, which is a schematic illustration of a UAV landing system, generally referenced600, for landing a UAV directly onto a land vehicle, in which the UAV is approaching the landing system downwind, constructed and operative in accordance with yet another embodiment of the disclosed technique. UAV landing system600generally includes a UAV602with a suspension cable604and a hook606, two rods610A and610B, a cable loop608, a cable609, and a land vehicle620which includes a wire bed630and a winch618. Vehicle620may be any type of land vehicle suitable for carrying the necessary equipment associated with landing system600, such as for example a truck. UAV landing system600provides point landing of UAV602directly onto vehicle602(without utilizing a runway and without associated landing preparations). One rod610A is mounted at a location on the ground beside vehicle620, while the other rod610B is mounted on vehicle620(alternatively, both rods610A,610B may be mounted on the ground). Cable loop608extends between rods610A and610B, and is coupled with cable609which is spooled around winch618. Rods610A and610B may extend sufficiently upward in order to enable the landing operations for UAV602(i.e., UAV landing approach; hook trajectory, hook latching, and cable release/retraction) to take place entirely above any obstacles located in the vicinity. The locations of rods610A and610B may also be adjusted in accordance with current landing conditions, such as the wind conditions (e.g., the rods may be positioned such that cable loop608is substantially perpendicular to the wind direction to facilitate latching).

Reference is now made toFIG. 6B, which is a schematic illustration of a subsequent stage of the landing system ofFIG. 6A, in which the latching has taken place. As UAV602passes downwind over rods610A and610B, hook606latches onto cable loop608. Rods610A,610B and cable loop608may be aligned or configured in such a way as to facilitate the latching with hook606(i.e., allowing for larger deviations in the UAV flight trajectory during the latching approach). Since cable loop608is situated away from vehicle620(rather than directly above vehicle620), hook606will not pass over vehicle during the landing approach, minimizing potential equipment damage and safety risks. After the latching, cable loop608undergoes tension and may subsequently detach from rod610A and/or rod610B (e.g., cable loop608may be coupled with rods610A,610B in a manner that results in quick detachment). Winch618implements controlled cable release/retraction to allow UAV602to continue along its flight trajectory after the latching has occurred. In particular, UAV602ascends while progressing downwind.

Reference is now made toFIG. 6C, which is a schematic illustration of a subsequent stage of the landing system ofFIG. 6A, in which the UAV is being pulled upwind. Following the latching and release of cable609as UAV602ascends and continues downwind (FIG. 6B), winch begins retracting cable609, gradually pulling UAV602backwards (upwind) and causing UAV609to turn around from its initial trajectory until it is eventually facing the upwind direction (i.e., executing an approximately 180° turn). While being pulled by cable609, UAV602maintains a minimum flight speed (e.g., at least above the stall speed) and a controlled flight altitude. UAV602may optionally deploy aerodynamic lift/drag augmentation mechanisms, such as a parachute, to facilitate the turning around maneuver (due to the natural tendency of the parachute to align with the pulling force axis of the retracting cable), as well as to enable UAV602to hover at a desired altitude. It is noted that a parasail canopy is a particularly useful type of parachute for facilitating the turning around of the UAV due to its natural directional alignment with the wind (as opposed to a parafoil type parachute). UAV602is gradually lowered onto wire bed630by the retraction of cable609. UAV602may alternatively be positioned (i.e., touchdown) directly onto a surface of vehicle620, or onto an alternative landing platform (i.e., rather than onto wire bed630). After landing, UAV602is optionally secured to vehicle620(e.g., using cable609and other suitable means), to avoid the UAV602inadvertently being repositioned or damaged due to strong winds.

A UAV may alternatively undergo a “tail-first” landing in accordance with the disclosed technique, in which the retracting cable does not cause the UAV to turn around to face the opposite direction from its initial flight trajectory (as depicted inFIG. 6C), but rather the UAV is pulled backwards while still facing the same direction. For example, if the UAV approaches the landing body downwind to execute the landing, then a tail-first landing would involve the UAV being hauled down onto the landing body while the front (i.e., the “nose”) of the UAV remains facing downwind. A tail-first landing may result if the UAV does not deploy a parachute at the appropriate time (i.e., around the peak of its ascent, prior to the initiation of the cable retraction,) or if a deployed parachute does not sufficiently assist the UAV to execute a full U-turn. Further alternatively, tail-first landing may result if the parachute is oriented in a manner that would cause the UAV to be pulled backwards by the retracting cable without turning, such as for a parasail, having its slotted lower rear portion oriented toward the front (nose) of the UAV. A head-first landing may be preferable, since the ordinarily thin tail surfaces are typically more delicate when touching down as compared to leading-edge surface that are normally rounded and more rigid. A tail-first landing may be implemented when it is desired to subsequently launch the UAV toward a direction opposite the direction of the initial UAV flight trajectory.

Reference is now made toFIG. 7which is a flow diagram of a method for landing a flying object onto a landing surface at a landing body, operative in accordance with an embodiment of the disclosed technique. In procedure702, parameters, including the wind speed and the wind direction, at the vicinity of the landing body are acquired. With reference toFIG. 1A, the wind speed, wind direction, and other relevant parameters at the vicinity of the landing body (e.g., ship120) are acquired prior to the intended landing of a flying object (e.g., UAV102). Other relevant parameters may include: current weather conditions (e.g., rain, fog); information regarding wind turbulence; information about the landing terrain, including potential obstacles; information about the state of a body of water (e.g., a sea) when landing on an aquatic vessel, such as the height and direction of waves and the speed and direction of water currents; information about the quality of the landing terrain when landing on a land vehicle, such as a paved road or off-road area; and the like. The parameters may be acquired using suitable measuring instruments and detectors located at or on the landing body or in the general vicinity. Alternatively, the parameters may be obtained from external sources via a data network, or may be input manually by a system operator.

In procedure704, parameters, including the speed, direction and altitude, of the flying object, are acquired. With reference toFIG. 1A, the speed, direction, and altitude of UAV102are acquired, along with any other relevant parameters (e.g., its current position relative to landing component150). The parameters may be acquired using suitable measuring instruments and detectors at UAV102, or may be input manually by a system operator. Variations in different types of UAVs (e.g., different UAV models) may be accounted for when acquiring the UAV parameters.

In procedure706, parameters, including the speed, direction and altitude, of the landing body, are acquired. With reference toFIG. 1A, the speed, direction, and altitude of ship120are acquired, along with any other relevant parameters. The parameters may be acquired using suitable measuring instruments and detectors at ship120, or may be input manually by a system operator.

In procedure708, current operational characteristics of the landing system components at the landing body are acquired. Referring toFIG. 2, the operational characteristics of the various elements of landing component150are obtained, such as the characteristics of cable support110, receiving latch108, and cable release/retraction mechanism (pulleys217,227and winches218,228). The various characteristics may include: position, availability, maximum cable extension length, maximum cable tensile strength, and other suitable parameters.

In procedure710, potential landing scenarios are generated in accordance with the acquired parameters and current operational characteristics. The extent of all possible landing scenarios is generated, e.g., via a processor and/or other components located at the landing body, taking into account all the acquired parameters (i.e., at the vicinity of the landing body, of the flying object, and of the landing body) and taking into account the operational characteristics of the landing system components. For example, each generated landing scenario may include: a set of landing approach parameters for the flying object, such as: flight speed, direction, and altitude; a set of operating parameters for the landing body, such as: travelling speed and direction; and a set of operating parameters for the activation or manipulation of at least one landing component. A generated landing scenario may also include the application of aerial maneuvers for effective utilization of the wind, the deployment of aerodynamic lift/drag augmentation mechanisms, cutting off the engine of the flying object, and the like. The generated scenarios may be presented to a system operator, along with limitations encountered, advantages and disadvantages, recommendations or other relevant information for each scenario. For example, several potential landing scenarios can be presented to an operator, with one option indicated as being most recommended. The landing scenarios and associated data may be updated in real-time based on changes in the acquired parameters or landing system operating characteristics and/or based on operator input.

In procedure712, a landing scenario is selected for implementation. One of the previously generated landing scenarios is selected for landing the flying object onto the landing body. The selection of the landing scenario may be performed automatically, such as by a processing unit, based on predefined criteria (e.g., the optimal landing scenario that meets required criteria for current landing conditions), and/or based on operator input. For example, an operator may provide feedback to the automated selection unit to influence the landing scenario selection, or the operator may directly select a preferable landing scenario. The operator may also make adjustments to the selected landing scenario, in advance or in real-time. Intervention by the operator may follow from consultation with suitable personnel, such as the ship command crew, regarding certain operational requirements (e.g., a mandatory sailing course).

In procedure714, the selected landing scenario is executed and the flying object is guided along at least one flight trajectory in accordance with the selected landing scenario, by managing the flying object flight controls and selectively activating and maneuvering the landing system components. In particular, the flying object is directed to approach the landing body such that a latching element suspended from the flying object latches onto a receiving cable coupled with the landing body (procedure716), and the receiving cable is released/retracted with a cable release/retraction mechanism, hauling the flying object onto a landing surface (procedure718). Referring toFIG. 2, UAV102is directed to approach ship120until hook106, suspended from UAV102via cable104, latches onto loop208on rod110mounted on ship120. Subsequently, winches218and/or228are activated to initially release and then gradually retract cables104and/or204, affecting the flight paths of UAV102and eventually hauling UAV102onto landing surface130on ship120. While following the landing scenario, UAV102may also be controlled or instructed to fly or operate in a certain manner, such as deploying aerodynamic lift/drag augmentation mechanisms, hovering at a desired altitude, initiating a turn, cutting off the engine power, and the like. For example, the executed landing scenario may include the following stages: UAV approaches landing body; cable latching/engagement; UAV ascent; deploying parachute when reaching maximum altitude (peak of ascent); UAV descending and drifting laterally under the effect of the wind; retracting cable to cease UAV descent; stabilizing UAV behind the landing body (e.g., ship); and finally, hauling the UAV down onto landing surface. Another exemplary landing scenario (as described inFIG. 8A) may include the following stages: UAV approaches ship; cable latching/engagement; UAV turning laterally with respect to the ship while ship sails upwind; UAV flying back-and-forth transverse to the wind/ship direction, generating a lag between the UAV and ship (along the direction of ship motion); and cable retraction to haul down the UAV onto the ship landing surface. A further exemplary landing scenario (as described inFIG. 8B) may include the following steps: UAV approaches ship; cable latching/engagement; UAV ascending along a vertical trajectory while the ship sails upwind; UAV descending gradually while undergoing drift; UAV ascending/descending repeatedly, generating a lag between the UAV and ship (along the direction of ship motion); and cable retraction to haul down the UAV onto the ship landing surface. A further exemplary landing scenario (as described inFIG. 3andFIGS. 4A-4H) includes UAV landing and subsequent stowage, as well as UAV take-off, via a side-door and elevator of the ship. Further landing scenarios may involve landing during strong wind conditions, and/or “straight-ahead” UAV landing (as described hereinbelow inFIGS. 9, 10A and 10B).

A command and control unit (not shown) may control or provide instructions to the flying object, landing body, and/or landing components. The landing system may include communication systems and mechanisms known in the art (e.g., radio, cellular, satellite, and the like), to communicate with the flying object and/or landing body while implementing the landing scenario. The landing scenario may be altered and adapted in real-time to account for practical considerations and/or changes in current conditions (e.g., changing weather).

It is appreciated that any of the procedures of the method ofFIG. 7may be automated (i.e., executed at least partially using a processor or computer). This provides various advantages as compared with only manual (operator controlled) execution, such as: obtaining data from sensors and landing body equipment and data systems, enabling POTL in a wider variety of environments and conditions; faster operation; the ability to consider a large number of variables and to calculate additional landing scenarios; the ability to prepare landing system components to operate with different types of flying objects (e.g., different UAVs having different characteristics); reduced operator training requirements and workload; and limited potential for human error (e.g., due to inexperience, fatigue, stress, and the like).

Reference is now made toFIG. 8A, which is a perspective view schematic illustration of an exemplary landing scenario, generally referenced800, that utilizes the wind to maneuver the UAV, operative in accordance with an embodiment of the disclosed technique. Landing scenario800employs a UAV landing system for landing a UAV802onto a ship801. The UAV landing system includes landing system components and is generally analogous to UAV landing systems disclosed hereinabove. Landing scenario800involves exploiting the current wind conditions for maneuvering UAV802with respect to ship801. Landing scenario800is illustrated in four stages that progress sequentially over time. In stage 1, ship801sails along a course heading opposite the wind direction (referenced805), i.e., ship801is sailing upwind. Meanwhile, UAV802flies upwind toward ship801at a speed far greater than the ship sailing speed. In stage 2, UAV802engages with the landing system on ship801, by latching a suspended latching element (e.g., hook) with a receiving cable hanging from at least one rod mounted on ship801. After the latching, UAV802turns (e.g., left) to head in a direction transverse to wind direction805, and the cable release/retraction mechanism of the landing system on ship801is activated to begin release/retraction of the receiving cable. In stage 3, UAV802is directed to fly back and forth substantially perpendicular to wind direction805, i.e., in an S-shaped pattern, in multiple flight legs that are transverse to the motion of ship801. For example, UAV802may be maneuvered to follow trajectory A, first flying outward (i.e., away from ship801), and then making a U-turn and flying back towards ship801, and so on. However, due to the drift effect of wind805, the actual trajectory that UAV802follows is represented by trajectory B. While UAV802follows the aforementioned S-shaped pattern flight maneuvers, ship801continues to sail, and hence there is a resultant lag (referenced “Y” inFIG. 8A) along the direction of ship motion between ship801and UAV802. UAV802may repeat multiple cycles of the S-shaped pattern flight maneuvers transverse to the motion of ship801while maintaining a normal flight speed (i.e., without slowing down), until a sufficient lag is achieved in order to enable the hauling in of UAV802via the cable release/retraction mechanism on ship801. In stage 4, the cable release/retraction mechanism retracts the receiving cable to haul down UAV802onto a landing surface on ship801. It is noted that landing scenario800employs a combination of the motion of ship801, the wind direction805, and the operation and maneuvering of UAV802, to enable the effective guidance of UAV802along a flight trajectory for landing onto ship801, without the use of a parachute or other landing accessories.

Reference is now made toFIG. 8B, which is a perspective view schematic illustration of another exemplary landing scenario, generally referenced810, that utilizes the wind to maneuver the UAV, operative in accordance with another embodiment of the disclosed technique. Landing scenario810employs a UAV landing system for landing a UAV802onto a ship801, as with the UAV landing system disclosed inFIG. 8A. Landing scenario810also involves exploiting the current wind conditions for maneuvering UAV802with respect to ship801. Landing scenario800is illustrated in four stages that progress sequentially over time. In stage 1, UAV802approaches ship801flying upwind, and engages with the landing system (i.e., latching with the receiving cable). In stage 2, UAV802ascends along a vertical trajectory, for a substantial duration, in accordance with the length of the receiving cable coupled with UAV802(which may be released further by the winch). The vertical climb naturally slows down the flight speed of UAV802, while the wind causes UAV802to also drift downwind805. Meanwhile, ship801continues along on its course upwind (i.e., heading opposite wind direction805). In stage 3, UAV802descends very gradually (e.g., as slow as possible), while still undergoing drift due to the wind. When UAV802reaches a lower altitude, a lag (referenced “Y”) results along the direction of ship motion between UAV802and ship801. UAV802may repeat multiple cycles of the aforementioned ascent and descent flight maneuver. When the resultant lag is sufficient for enabling the hauling in of UAV802via the cable release/retraction mechanism on ship801, UAV802ceases the ascent/descent flight maneuvers. In stage 4, the cable release/retraction mechanism on ship801is activated to retract the receiving cable to haul down UAV802onto a landing surface on ship801. It is noted that the ascending and descending of UAV802during landing scenario810serves to slow down UAV802, and thus extend its flight duration, so as to increase the wind drift while the forward motion of ship801proceeds. The resultant lag enables effective guidance of the UAV802onto ship801despite the UAV802initially overtaking ship801after the latching and cable engagement (e.g., if the speed of UAV802is greater than that of ship801even when factoring in the wind). It is appreciated that landing scenarios800and810represent exemplary flight maneuvers, and that alternative flight maneuvers may also be employed to utilize the wind for landing the UAV in conjunction with a UAV landing system of the disclosed technique.

Reference is now made toFIGS. 9A, 9B and 9C.FIG. 9Ais a schematic illustration of a UAV landing system, generally referenced900, for straight-ahead landing of a UAV, constructed and operative in accordance with yet another embodiment of the disclosed technique.FIG. 9Bis a schematic illustration of a subsequent stage of the UAV landing system900ofFIG. 9A, at which the latching has taken place.FIG. 9Cis a schematic illustration of a subsequent stage of the UAV landing system900ofFIG. 9A, at which a parachute is deployed to decrease the UAV velocity. Landing system900is operative for landing a UAV, referenced902, which includes a suspension cable904with a hook906. Landing system900includes a proximal winch918, a remote winch919, a receiving cable having two portions909A and909B, a pulley907, a cable loop908, and a pair of rods910A and910B. It is noted that pulley907, winch918, and cable portion909A are optional. Cable portion909B is coupled with winch919and with pulley907. Cable portion909A is coupled with winch918. Cable loop908is coupled with cable portions909A and909B at connection point916. Cable loop908is supported by rods910A and910B in a manner such that hook906of UAV902can successfully latch onto and engage with cable loop908. Upon latching of hook906with cable loop908, the resultant tension at receiving cable portions909A and909B triggers remote winch919, which begins retracting receiving cable909B (i.e., at a rate that is faster than the current flight speed of UAV902) and gradually hauling down UAV902. Pulley907guides the receiving cable portion909B as it is being retracted by winch919, and enforces the landing of UAV902onto a touchdown point located prior to remote winch919. The touchdown point may be at a landing surface, which may include a dedicated cushioning platform (e.g., a wire mesh bed). After hook906has latched onto cable loop908(FIG. 9B), UAV902undergoes a rapid decrease of velocity such that cable909has sufficient tension to properly guide UAV902. This velocity decrease may be achieved by a parachute deployed by UAV902(as shown inFIG. 9C) or the use of other types of flight decelerators (e.g., spoilers, a retro rocket), by cutting of the engine of UAV902, by activating breaks of landing gears upon touchdown, and/or via winch918creating additional tension on receiving cable portion909A in coordination with winch919creating tension on receiving cable portion909B so as to pull UAV902down and forwards. It is noted that the pulling force of winch919is generally much greater than that of winch918. UAV902may be directed to deploy the parachute at an appropriate time (e.g., upon latching of hook906with cable loop908), to provide sufficient velocity decrease of UAV902to enable effective retraction of receiving cable909by winch919and subsequent UAV902landing.

FIGS. 9A, 9B and 9Cdepict a “straight-ahead” landing of UAV902, in which UAV902is landed while constantly facing forward with respect to its landing flight trajectory (i.e., heading along the same direction as the flight trajectory employed during the landing approach), without turning around to face the opposite direction (similar to the “tail-first landing” discussed hereinabove), and while being pulled forward and down (as opposed to being pulled backwards and down, as with the “tail-first” landing). In general, UAV landing system900provides a straight-ahead landing by primarily activating remote winch919sufficiently quickly in order to retract the receiving cable portion909B and haul down UAV902onto the landing surface, while UAV902is simultaneously decelerated (e.g., via parachute940). Straight-ahead landing may be preferred for heavier UAVs, or when other considerations dictate continuous forward motion during the UAV landing (as with landing system1000described hereinbelow).

Reference is now made toFIG. 10Awhich is a schematic illustration of a landing system, generally referenced1000, for sequentially landing multiple unmanned flying objects, constructed and operative in accordance with yet a further embodiment of the disclosed technique. Landing system1000includes a railway, generally referenced1010, which includes a trap segment1012, a touchdown region1014, a maintenance region1016, and a launching region1018. Railway1010may be mounted onto an aquatic vessel in motion (e.g., a sailing ship), a land vehicle in motion, or onto a stationary platform (e.g., at land, at sea, or airborne). Landing system1000further includes a latching mechanism1008located at touchdown region1014, maintenance mechanisms1020located at maintenance region1016, and launching assistance mechanisms1022located at launching region1018. Landing system1000is operative for landing unmanned flying objects, such as UAVs1002. Each UAV1002includes a suspension cable1004with a latching element1006(e.g., a hook). UAV1002approaches railway1010along a landing approach trajectory towards trap segment1012. Trap segment1012may be embodied by two separate rails of railway1010, each of which extends outward laterally in a V-shape, defining an angle therebetween, as depicted inFIG. 10A, although trap segment1012may alternatively be configured in a different manner. UAV1002and/or landing system1000may optionally include a global positioning system (GPS) or other type of navigational system that is used to direct UAV1002toward trap segment1012of railway1010. Alternatively, UAV1002navigation may be remotely controlled at a command/control station.

Referring toFIG. 10A, a UAV1002A to be landed onto railway1010approaches trap segment1012. UAV1002A is guided along a landing approach trajectory such that suspension cable1004A and latching element1006A are positioned in between the two lateral V-shaped portions of railway1010forming trap segment1012. UAV1002A continues forward past the intersection between the two lateral V-shaped portions (i.e., intersection point1007), and continuing along a gap extending through railway1010(depicted by a dashed line inFIG. 10A). Latching element1006A subsequently engages with latching mechanism1008, coupling UAV1002A with latching mechanism1008via cable1004A. It is noted that the V-shape of trapping segment1012assists in guiding suspension cable1004A and latching element1006A toward latching mechanism1008to enable successful latching. It is further noted that while the main section of railway1010generally includes two rails separated by a gap, to allow suspension cable1004of UAV1002to pass through while being pulled along by latching mechanism1008, alternative configurations (e.g., a single main rail) are also applicable provided that UAV can be hauled down onto railway1010via latching mechanism1008in a similar manner.

Reference is now made toFIG. 10B, which is a detailed view schematic illustration depicting different stages of touchdown in conjunction with the latching mechanism1008of the landing system1000ofFIG. 10A. Latching mechanism1008includes a plurality of clasps1009, which rotate sequentially along a moving chain1011arranged in a triangular-shaped track situated underneath railway1010at touchdown region1014. A plurality of caster wheels (referenced1013,1015,1017) enable the continuous rotation of chain1011along the track. It is appreciated that latching mechanism1008represents an exemplary mechanism configuration, while alternative latching mechanisms are also applicable in accordance with the disclosed technique. Railway1010may include a triggering element (not shown), such as a switch, disposed adjacent to intersection point1007, which triggers the activation (high-speed rotation) of latching mechanism1008. The linear velocity of the rotating chain1011of latching mechanism1008is greater than the velocity of the UAV1002during its landing trajectory. As a result of the higher speed rotation of chain1011, cable1004serves to guide UAV1002down onto railway1010, until UAV1002comes to a complete stop within touchdown region1014.

A UAV1002A is shown in an initial touchdown stage (designated “A”), where latching element1002A of UAV1002A has just latched with one of the clasps1009A located at the inclining portion of chain1011(i.e., in between wheels1013and1015) as UAV1002reaches the beginning of latching mechanism1008(i.e., just beyond intersection point1007). UAV1002may optionally undergo deceleration at this stage, such as by activating aerodynamic braking mechanisms (e.g., rudder splitting, deploying a drag parachute, activating railway friction, and the like) upon command. After latching onto clasp1009A, latching element1006A is carried upward by the rotation of chain1011toward wheel1015. A UAV1002is shown at a later touchdown stage (designated “B”), at which the latching element1006B of UAV1002B was previously latched within clasp1009B, which is now located at the declining portion of chain1011(i.e., in between wheels1015and1017), and the rotation of chain1011is pulling cable1004B down and forward (toward wheel1017), thereby hauling down UAV1002B onto railway1010. A UAV1002C is shown at yet a later touchdown stage (designated “C”), at which the latching element1006C of UAV1002C was previously latched within clasp1009C, which is now located further along the declining portion of chain1011(i.e., in between wheels1015and1017), where the rotation of chain1011has pulled cable1004C sufficiently down and forward such that UAV10020has now completed touchdown onto railway1010. After the landed UAV1002has come to a complete stop, the latching element1006may detach from clasp1009. UAV1002may then be taken further along railway1010toward maintenance region1016and/or launching region1018.

Following the landing of a UAV1002onto railway1010as described hereinabove, another UAV may follow and land onto railway1010in a similar manner. For example, referring back toFIG. 10A, a first UAV1002D (i.e., in a sequence of multiple UAVs having arrived at landing system1000) is shown at launching region1018preparing for take-off; a second UAV1002C is shown at maintenance region1016after having completed touchdown; a third UAV1002B is shown during the latching and touchdown stage over touchdown region1014; while a fourth UAV1002A is shown along a landing approach trajectory above trap segment1012.

UAV1002may undergo maintenance operations and/or general preparations for an upcoming flight (e.g., servicing, inspection, refueling, rocket booster mounting, and the like) at maintenance region1016, with use of maintenance mechanisms1020. UAV1002may be stowed away elsewhere on the landing body (e.g., if deemed unserviceable, or if not scheduled for imminent take-off). Following the necessary maintenance/preparations, the UAV1002may be brought along runway1010toward launching region1018, where it may then be launched from railway1010. It is appreciated that the landing of a UAV onto landing system1000takes place relatively quickly (i.e., latching mechanism1008provides deceleration and touchdown of a UAV1002over a relatively short distance along railway1010), and thus landing system1000facilitates the sequential landing of multiple UAVs over a substantially short period of time. It is further appreciated that landing system1000essentially implements a straight-ahead UAV landing, similar to landing system900described hereinabove (FIGS. 9A, 9B and 9C), where the landing UAV1002is pulled forward and down onto the landing surface while continuing to face the same direction (i.e., without turning).

It will be appreciated by persons skilled in the art that the technique is not limited to what has been particularly shown and described herein above.