Patent Description:
An unmanned vehicle, which may also be referred to as an autonomous vehicle, is a vehicle capable of travel without a physically present human operator. Various types of unmanned vehicles exist for various different environments. For instance, unmanned vehicles exist for operation in the air, on the ground, underwater, and in space. Unmanned vehicles also exist for hybrid operations in which multi-environment operation is possible. Unmanned vehicles may be provisioned to perform various different missions, including payload delivery, exploration/reconnaissance, imaging, public safety, surveillance, or otherwise. The mission definition will often dictate a type of specialized equipment and/or configuration of the unmanned vehicle.

Controlling unmanned vehicles can be problematic especially when there are a large number of vehicles in close proximity. For unmanned aerial vehicles (UAVs), the terminal area from which the UAVs are staged (e.g., loaded, charged, stored, etc.) can be a high congestion choke point requiring specialized procedures to maintain an efficient, safe, and orderly orchestration of their movements and behavior.

<CIT> discloses an unmanned aerial vehicle (UAV) that includes one or more sources of propulsion, a power source, and communication system. The UAV also includes a controller coupled to the communication system, the power source, and the one or more sources of propulsion. The controller includes logic that when executed by the controller causes the UAV to perform operations, including measuring a power source charge level of the UAV; sending a signal including the power source charge level of the UAV to an external device; receiving movement instructions from the external device; and engaging the one or more sources of propulsion to move the UAV from a first location on a storage rack to a second location within a storage facility.

<CIT> discloses systems and methods that include UAVs that serve to assist carrier personnel by reducing the physical demands of the transportation and delivery process. UAV support mechanisms are utilized to load and unload parcel carriers to the UAV chassis, and the UAV lands on and takes off from the UAV support mechanism to deliver parcels to a serviceable point. The UAV includes computing entities that interface with different systems and computing entities to send and receive various types of information.

Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. Not all instances of an element are necessarily labeled so as not to clutter the drawings where appropriate. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles being described.

Embodiments of a system, apparatus, and method for orchestrating the landing, launching, and loading behaviors of unmanned aerial vehicles (UAVs) operating proximate to a terminal area from which the UAVs are staged for delivering packages are described herein. In the following description numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

UAVs that are provisioned to perform package delivery may operate out of a dedicated operations facility where more than one UAV is in operation. At these operations facilities (also referred to as a terminal area), it is imperative that terminal area maneuvers are efficient and minimize potential conflict between UAVs as well as between UAVs and any authorized personnel (e.g., merchant attendants) that may be at the operations facility. Two important conditions are the landing of UAVs upon return to the terminal area and the launching and successive package loading for departure from the terminal area.

One particular challenge is for UAVs that are loaded with packages at a terminal area that has minimal infrastructure/equipment beyond the UAVs, packages, and charging pads. The operational techniques and infrastructure disclosed herein detail terminal navigation and control behaviors as they pertain to landing, charging, launching, and loading UAVs with packages for aerial delivery. The techniques seek to improve efficiencies and reduce wasted flight times that negatively impact battery charges and reduce flight durations.

<FIG> is a plan view illustration of a terminal area <NUM> for staging UAVs <NUM> that deliver packages to a neighborhood, in accordance with an embodiment of the disclosure. When UAV operations reach significant scale, UAV operators will need to maintain large fleets of UAVs potentially in locations with minimal infrastructure. This is particularly true in the case where UAVs are used for package delivery and staging areas may need to be positioned relatively close to the customer base. A likely scenario for UAV storage is for a UAV fleet to be staged from a facility, such as terminal area <NUM> (e.g., a warehouse or even open field with minimal supporting buildings <NUM> surrounding the open field), during times of recharging and loading. For these terminal areas, operators will need methods to manage these fleets, including how to get UAVs <NUM> in and out of terminal area <NUM>, and in the case of package delivery that originates at the same facility, how to load packages onto the aircraft in an efficient manner that minimizes the time delay between a package being ready for delivery and the customer receiving the package. Presented here are ways to move, organize, and dynamically rearrange UAVs at terminal area <NUM>.

<FIG> and <FIG> illustrate an UAV <NUM> that is well suited for delivery of packages, in accordance with an illustrative example of the disclosure. <FIG> is a topside perspective view illustration of UAV <NUM> while <FIG> is a bottom side plan view illustration of the same. UAV <NUM> is one possible implementation of UAVs <NUM> illustrated in <FIG>, although other types of UAVs may be implemented as well.

The illustrative example of UAV <NUM> is a vertical takeoff and landing (VTOL) UAV that includes separate propulsion units <NUM> and <NUM> for providing horizontal and vertical propulsion, respectively. UAV <NUM> is a fixed-wing aerial vehicle, which as the name implies, has a wing assembly <NUM> that can generate lift based on the wing shape and the vehicle's forward airspeed when propelled horizontally by propulsion units <NUM>. The illustrative example of UAV <NUM> has an airframe that includes a fuselage <NUM> and wing assembly <NUM>. In one illustrative example, fuselage <NUM> is modular and includes a battery module, an avionics module, and a mission payload module. These modules are secured together to form the fuselage or main body.

The battery module (e.g., fore portion of fuselage <NUM>) includes a cavity for housing one or more batteries for powering UAV <NUM>. The avionics module (e.g., aft portion of fuselage <NUM>) houses flight control circuitry of UAV <NUM>, which may include a processor and memory, communication electronics and antennas (e.g., cellular transceiver, wifi transceiver, etc.), and various sensors (e.g., global positioning sensor, an inertial measurement unit, a magnetic compass, a radio frequency identifier reader, etc.). The mission payload module (e.g., middle portion of fuselage <NUM>) houses equipment associated with a mission of UAV <NUM>. For example, the mission payload module may include a payload actuator <NUM> (see <FIG>) for holding and releasing an externally attached payload (e.g., package for delivery). In some illustrative examples, the mission payload module may include camera/sensor equipment (e.g., camera, lenses, radar, lidar, pollution monitoring sensors, weather monitoring sensors, scanners, etc.). In <FIG>, an onboard camera <NUM> is mounted to the underside of UAV <NUM> to support a computer vision system for visual triangulation and navigation as well as operate as an optical code scanner for reading visual codes affixed to packages. These visual codes may be associated with or otherwise match to delivery missions and provide the UAV with a handle for accessing destination, delivery, and package validation information.

As illustrated, UAV <NUM> includes horizontal propulsion units <NUM> positioned on wing assembly <NUM> for propelling UAV <NUM> horizontally. UAV <NUM> further includes two boom assemblies <NUM> that secure to wing assembly <NUM>. Vertical propulsion units <NUM> are mounted to boom assemblies <NUM>. Vertical propulsion units <NUM> providing vertical propulsion. Vertical propulsion units <NUM> may be used during a hover mode where UAV <NUM> is descending (e.g., to a delivery location), ascending (e.g., at initial launch or following a delivery), or maintaining a constant altitude. Stabilizers <NUM> (or tails) may be included with UAV <NUM> to control pitch and stabilize the aerial vehicle's yaw (left or right turns) during cruise. In some illustrative examples, during cruise mode vertical propulsion units <NUM> are disabled or powered low and during hover mode horizontal propulsion units <NUM> are disabled or powered low.

During flight, UAV <NUM> may control the direction and/or speed of its movement by controlling its pitch, roll, yaw, and/or altitude. Thrust from horizontal propulsion units <NUM> is used to control air speed. For example, the stabilizers <NUM> may include one or more rudders 208a for controlling the aerial vehicle's yaw, and wing assembly <NUM> may include elevators for controlling the aerial vehicle's pitch and/or ailerons 202a for controlling the aerial vehicle's roll. As another example, increasing or decreasing the speed of all the propeller blades simultaneously can result in UAV <NUM> increasing or decreasing its altitude, respectively.

Many variations on the illustrated fixed-wing aerial vehicle are possible. For instance, aerial vehicles with more wings (e.g., an "x-wing" configuration with four wings), are also possible. Although <FIG> and <FIG> illustrate one wing assembly <NUM>, two boom assemblies <NUM>, two horizontal propulsion units <NUM>, and six vertical propulsion units <NUM> per boom assembly <NUM>, it should be appreciated that other variants of UAV <NUM> may be implemented with more or less of these components.

It should be understood that references herein to an "unmanned" aerial vehicle or UAV can apply equally to autonomous and semi-autonomous aerial vehicles. In a fully autonomous implementation, all functionality of the aerial vehicle is automated; e.g., pre-programmed or controlled via real-time computer functionality that responds to input from various sensors and/or pre-determined information. In a semi-autonomous implementation, some functions of an aerial vehicle may be controlled by a human operator, while other functions are carried out autonomously. Further, in some illustrative examples, a UAV may be configured to allow a remote operator to take over functions that can otherwise be controlled autonomously by the UAV. Yet further, a given type of function may be controlled remotely at one level of abstraction and performed autonomously at another level of abstraction. For example, a remote operator may control high level navigation decisions for a UAV, such as specifying that the UAV should travel from one location to another (e.g., from a warehouse in a suburban area to a delivery address in a nearby city), while the UAV's navigation system autonomously controls more fine-grained navigation decisions, such as the specific route to take between the two locations, specific flight controls to achieve the route and avoid obstacles while navigating the route, and so on.

<FIG> is a perspective view illustration of a terminal area <NUM> for UAVs (e.g., UAVs <NUM>) having merchant facilities <NUM> that prepare packages for delivery disposed about a periphery of a staging array <NUM>, in accordance with an embodiment of the disclosure. Terminal area <NUM> is one possible implementation of terminal area <NUM> illustrated in <FIG>. Also depicted in <FIG> are parts of a control system <NUM> (e.g., a "control tower") for the UAVs including network <NUM>, storage <NUM>, controller <NUM> (e.g., servers in a distributed system, local computer, a combination thereof, or the like), and communication system <NUM> (e.g., RF transceiver, WiFi transceiver, cellular transceivers, Bluetooth, or the like). The illustrated embodiment of staging array <NUM> includes pads <NUM> organized into an array (e.g., a rectangular array though other shapes may be used). A maintenance area <NUM> is also depicted.

Pads <NUM> serve as resting locations for UAVs <NUM> between delivery missions. In general, pads <NUM> may be referred to generically as "landing pads" or just "pads. " Some or all of pads <NUM> may also include charging circuitry for charging the onboard batteries within UAVs <NUM> while resting or waiting for assignment of a delivery mission. Pads <NUM> that include charging circuitry may also be referred to as "charging pads. " In general, pads <NUM> within the interior of staging array <NUM> are charging pads while pads <NUM> located about the perimeter or periphery of staging array <NUM> may or may not be charging pads. Pads <NUM> located about the periphery of staging array <NUM> are closest to merchant facilities <NUM>. Due to their proximity and their relative safety for merchant attendants <NUM> to approach from merchant facilities <NUM>, these pads are used for loading UAVs <NUM> with packages for aerial delivery, and thus also referred to as "peripheral loading pads.

Terminal area <NUM> represents a staging area from which UAVs <NUM> may operate to deliver packages to customers within a neighborhood using low or minimal infrastructure. Terminal area <NUM> may be implemented as a covered or partially covered facility (e.g., a warehouse, carport, etc.) or even an open field. In an open field concept, merchant facilities <NUM> may be permanent, semi-permanent, or temporary structures. For example, merchant facilities <NUM> may be tents, trailers, vehicles (e.g., food truck), mobile structures, or otherwise. Merchant facilities <NUM> provide a local base of operations for merchants or vendors to locally stock products or even prepare, assemble, and/or package products for aerial delivery. Merchant facilities <NUM> may operate as small staging facilities adjunct to larger businesses operating in the area that are using the aerial delivery service provided by the fleet of UAVs <NUM> and control system <NUM>. As such, merchant attendants <NUM> may be employees of the individual merchants or of the aerial delivery service provider.

Terminal area <NUM> enables UAVs <NUM> to stage from a low or minimal infrastructure facility. The operation techniques described below facilitate a pick-up-over-pad operation where UAVs <NUM> are loaded with their packages while hovering directly over, or within close proximity of, the peripheral loading pads <NUM>. Terminal area <NUM> itself may be a permanent staging area, a semi-permanent staging area, or even a temporary staging area. This low-cost operational structure enables rapid deployment of a localized aerial delivery service (e.g., <NUM>-mile radius) in times of urgent or temporary need (e.g., natural disasters, festivals, conventions, seasonal events, etc.).

During operation of the pick-up-over-pad strategy, UAVs <NUM> are directed to land on or maneuver to interior charging pads within staging array <NUM> for charging. As peripheral loading pads become available and the individual UAVs <NUM> are deemed sufficiently charged and ready for a new delivery mission, the UAVs <NUM> relocate or migrate from the interior charging pads towards the peripheral loading pads under their own propulsion. This migration may be choreographed by control system <NUM>, or even occur as a series of decentralized decisions made by the individual UAVs <NUM>. In one embodiment, the delivery missions are loaded into control system <NUM> as customer orders or merchant delivery requests are received via network <NUM>. The delivery missions may be associated with specific packages by merchant attendants <NUM> at merchant facilities <NUM> and assigned to UAVs <NUM> over communication system <NUM>. The UAVs <NUM> that are ready and waiting on a peripheral loading pad <NUM> are prioritized for assignment of a new delivery mission and loading of the associate package.

The illustrated embodiment of terminal area <NUM> includes maintenance area <NUM> to provide routine and/or remedial services to UAVs <NUM> in a supporting capacity to the aerial delivery service. Maintenance area <NUM> provides a location from which maintenance or repair technicians may operate and even work on UAVs <NUM>. Maintenance or repair services may include swapping batteries, decommissioning UAVs, initial deployment of new UAVs <NUM> into the delivery fleet, performing repairs or scheduled maintenance, reconfiguring/provisioning modular components of UAVs <NUM> for specialized missions, or otherwise. UAVs <NUM> may automatically, or upon request, relocate to maintenance area <NUM> under their own power when possible, or be physically relocated by a service technician (e.g., human attendant) when needed.

<FIG> is a flow chart illustrating a process <NUM> including various landing behaviors of the UAVs <NUM> when executing delivery missions, in accordance with an illustrative example of the disclosure. The order in which some or all of the process blocks appear in process <NUM> should not be deemed limiting. Rather, one of ordinary skill in the art having the benefit of the present disclosure will understand that some of the process blocks may be executed in a variety of orders not illustrated, or even in parallel.

Upon returning to a centralized operations facility such as terminal area <NUM>, there may be significant air traffic congestion. One method to aid in congestion mitigation is to allocate and reserve dedicated flight altitude slices for specific purposes (e.g. incoming UAV traffic, outgoing UAV traffic, intra-facility UAV traffic). These dedicated flight altitude slices could be further separated based on direction of planned travel (e.g. incoming traffic approaching from the North vs. from the South). <FIG> illustrates example flight altitude slices <NUM>, <NUM>, and <NUM> over staging array <NUM>. In the illustrated embodiment, intra-facility UAV traffic is assigned the lowest flight altitude slice <NUM>, outbound UAV traffic is assigned the mid-level flight altitude slice <NUM>, and inbound UAV traffic is assigned the highest flight altitude slice <NUM>. Of course, other combinations may be implemented.

Returning to <FIG>, in a process block <NUM>, control system <NUM> analyzes inbound, outbound, and intra-facility traffic loads. Based upon the existing traffic loads, flight altitude slices <NUM>, <NUM>, and <NUM> may be dynamically adjusted to better accommodate the needs of the UAV fleet and efficiently share the available airspace (process block <NUM>). These adjustments may be real-time determined, periodically adjusted according to a schedule (e.g., time of day and/or season), or ad-hoc. For example, at the beginning of lunch time, outbound UAV traffic may be in greater demand while nearer to the end of lunch time inbound UAV traffic may be in greater demand. Accordingly, in one embodiment, flight altitude slice <NUM> assigned to outbound UAV traffic is temporarily expanded at the beginning of a lunch time and flight altitude slice <NUM> assigned to inbound UAV traffic is expanded at an end of the lunch time. Other adaptable schemes may be custom tailored to the demands of a particular terminal area <NUM>.

Once inside the operations facility an inbound UAV <NUM> needs to land on one of pads <NUM> within staging array <NUM> for charging. This charging pad may typically be prescheduled with the UAV's delivery mission (process block <NUM>). In other words, the particular landing/charging pad <NUM> may be predetermined by a central operations server (e.g., controller <NUM>) and specified in the delivery mission as the terminal waypoint for the UAV. However, in some scenarios, the specific landing/charging pad <NUM> may need to be reassigned/reallocated (process block <NUM>) upon approach or arrival due to congestion or interruption of the specified pad <NUM> (decision block <NUM>). Again, this reallocation may be assessed by a central operation server, such as controller <NUM>.

In yet other scenarios, the UAV itself may determine that the designated pad <NUM> is obstructed (decision block <NUM>), in which case the UAV itself may make an ad-hoc, self-determination that it needs to select a new landing/charging pad <NUM> much like how a human driver selects a parking spot. In this latter scenario, the UAV may use onboard camera <NUM> as part of a computer vision system to determine an available landing pad <NUM> by recognizing certain visual cues. For example, as illustrated in <FIG>, landing pads <NUM> may include one or more visual patterns <NUM> disposed thereon. The visual pattern may be a series of contiguous alternating stripes, matrix barcodes, 2D visual codes (e.g., quick response codes), or otherwise. If a given pad <NUM> is obstructed (e.g., taken by another UAV <NUM>), then visual pattern <NUM> may be at least partially hidden. If the expected pattern is disrupted, the inbound UAV will determine that the designated landing pad <NUM> is no longer suitable and automatically search for (e.g. visually) or request a new landing pad <NUM>. This ability to automatically find a suitable landing pad may also be used as a fallback measure by the UAVs <NUM>, if communications are lost with controller <NUM>, or as a final landing verification (safety measure) in conjunction with a pre-determined landing location specified in its delivery mission.

Upon landing, UAVs <NUM> may have provisions to automatically recharge their batteries. These provisions may include physical electrodes on the bottom side of the UAVs <NUM> that contact electrodes on charging pads <NUM>. If UAV <NUM> does not engage correctly with charging pad <NUM>, charging will not commence. A sufficient electrical connection may not be established due to a variety of reasons including poor orientation, debris on the electrical contacts (e.g., dirt, leaves, etc.), corrosion, or otherwise. In the event electrical contact is not properly established between UAV <NUM> and charging pad <NUM> (decision block <NUM>), UAV <NUM> can self-detect that charging has not started (despite the aircraft having terminated its mission) and make additional attempts (process blocks <NUM> and <NUM>) to properly engage with the charging infrastructure. In the illustrative example, the first attempt at establishing a sufficient electrical connection includes pulsing one or more vertical lift rotors <NUM> to "wiggle" the UAV (process block <NUM>). The UAV <NUM> may attempt multiple consecutive wiggle maneuvers to establish a connection. If this still does not establish an electrical connection, then the UAV <NUM> may drive the vertical lift rotors to "hop" up and down (e.g., hop less than <NUM> high) on the charging pad <NUM> to establish a connection. Again, the UAV <NUM> may attempt multiple consecutive hops. Finally, if the UAV <NUM> is unable to successfully initiate charging, it may automatically remove itself from the available fleet by setting its state to "maintenance required" (process block <NUM>). The UAV <NUM> may send a signal to controller <NUM> requesting service, reposition to a new charging pad <NUM>, or reposition to maintenance area <NUM> to obtain service. On the other hand, once charging does commence, the UAV <NUM> will charge its batteries until it has reached a threshold charge level deemed ready to execute a next delivery mission (process block <NUM>).

For package delivery operations by UAVs, it is important to minimize the time between aircraft takeoff and package loading to reduce wasted energy consumption of a limited capacity battery. The pick-up-over-pad techniques described below apply to situations where a package is not directly loaded into a stationary UAV. The techniques employed enable and coordinate a close coupling of package availability (e.g. prepared, ready to be loaded) and aircraft takeoff/launch. These techniques are appropriate for UAVs which may be self-loading (e.g. the UAV performs the final package attachment through, for example, a hook and winch system) or which some level of human interaction to initiate the package loading (e.g. attaching a package to the aforementioned hook or other attachment point) is still required.

<FIG> is a flow chart illustrating launching and loading behaviors of UAVs <NUM> when executing delivery missions, in accordance with an embodiment of the disclosure. The order in which some or all of the process blocks appear in process <NUM> should not be deemed limiting. Rather, one of ordinary skill in the art having the benefit of the present disclosure will understand that some of the process blocks may be executed in a variety of orders not illustrated, or even in parallel.

In a process block <NUM>, a given UAV <NUM> is charged on an interior charging pad <NUM> after completing its previous delivery mission. As UAVs <NUM> reach a threshold level of charge, they reposition themselves under their own propulsion from the interior charging pads <NUM> of staging array <NUM> to a peripheral loading pad <NUM> as those pads become available (process block <NUM>). Peripheral loading pads <NUM> are both closer to the merchant facilities <NUM> and safer for merchant attendants <NUM> to approach.

When a package becomes available for delivery at a merchant facility <NUM> (decision block <NUM>), it is associated with a delivery mission and assigned to an available, mission ready UAV <NUM>. The assigned UAV is identified to the merchant attendant <NUM> so that the merchant attendant <NUM> knows which UAV to load (process block <NUM>). For example, in one embodiment, the assigned UAV <NUM> may identify itself by illuminating one or more lights <NUM> disposed on the UAV. These lights may be color coded and/or have a coded blink sequence to improve disambiguation between multiple UAVs <NUM> launching around the same time. In another embodiment, the lights <NUM> may alternatively (or additionally) be disposed on, or otherwise associated with, the peripheral loading pad <NUM> upon which the assigned UAV <NUM> is waiting. In yet another embodiment, merchant attendants <NUM> may wear head wearable displays that identify the assigned UAV <NUM> with an augmented reality image that operates as a virtual image overlay to the real-world. For example, the augmented reality image may be a virtual arrow <NUM> superimposed on the merchant attendant's vision positioned over the UAV <NUM> assigned to the particular delivery mission. Other augmented images or icons may be implemented. Of course, one or more of the above identification techniques may be used in conjunction with each other.

Effective and efficient identification of the assigned UAV helps synchronize UAV takeoff with the approach of the merchant attendant <NUM> (process block <NUM>). Other synchronization techniques may also be implemented. For example, proximity sensors may be used to sense or monitor the merchant attendant's proximity to the assigned UAV <NUM>. When the merchant attendant <NUM> crosses a threshold proximity <NUM>, the assigned UAV <NUM> may be automatically triggered to launch and rise to a loading height (e.g., <NUM> to <NUM>) in preparation of loading the package. The proximity sensor may be disposed on the UAV, the launch pad, or otherwise integrated with terminal area <NUM>. The proximity sensor may be implemented using video cameras, ultrasonic sensors, infrared sensors, time of flight sensors, various wireless technologies known in the art of proximity sensing, or otherwise.

In some embodiments, the UAV may perform other active maneuvers to reduce hover times and improve loading efficiency. For example, UAV <NUM> may move towards merchant attendant <NUM> as the merchant attendant is approaching the UAV. Wasted loading time may be further reduced by having a UAV <NUM> deploy its line and connection point in a tightly synchronized manner (process block <NUM>). Referring to <FIG>, as UAV <NUM> launches from pad <NUM>, it may operate its onboard winch to deploy the line and connection point <NUM> in a synchronized manner. For example, UAV <NUM> may dispense the line and connection point <NUM> at a rate <NUM> that matches its ascension rate <NUM> so as to maintain connection point <NUM> at a substantially constant height as the UAV <NUM> ascends. This enables the merchant attendant <NUM> to load the UAV <NUM> with package <NUM> while the UAV <NUM> is ascending to start its delivery mission. In yet other embodiments, UAV <NUM> may use its computer vision system and onboard camera <NUM> to track the location of connection point <NUM> and keep it steady in cross winds by adjusting its own position, or even track the position of connection point <NUM> relative to merchant attendant <NUM> and actively guide connection point <NUM> towards merchant attendant <NUM>.

The packages (e.g., package <NUM>) may be coded to associate each package with its delivery mission. In one embodiment, the code is an optical code fixed to the exterior of the package (e.g., sticker with barcode or other 2D code). In other embodiments, the code is an RFID code embedded in or on the package. A package that is otherwise ready for aerial delivery may be matched to its mission (or otherwise validated) by scanning the code (process block <NUM>). In one embodiment, the code is scanned by the merchant attendant <NUM> just prior to (or immediately after) attaching the package to the UVA <NUM>. In another embodiment, the code is scanned by the UAV <NUM> after recoiling its line and tucking the package up under its fuselage. The UAV <NUM> may include an onboard scanner (e.g., onboard camera <NUM>) for reading optical codes or RFID codes. Validation may also include measuring the weight of the package attached and comparing it against an expected weight range detailed in the delivery mission. Weight measurement may be executed via the onboard winch or even indirectly via vertical thrust needed to maintain UAV altitude. Finally, in a process block <NUM> the UAV <NUM> delivers its package to the customer via an aerial route.

A tangible machine-readable storage medium includes any mechanism that provides (i.e., stores) information in a non-transitory form accessible by a machine (e.g., a computer, network device, personal digital assistant, manufacturing tool, any device with a set of one or more processors, etc.). For example, a machine-readable storage medium includes recordable/non-recordable media (e.g., read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.).

While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, which is defined by the appended claims, as those skilled in the relevant art will recognize.

Claim 1:
A method of controlling unmanned aerial vehicles, UAVs, (<NUM>) operating in proximity to a terminal area (<NUM>) from which the UAVs are staged, the method comprising:
charging (<NUM>) a plurality of the UAVs on charging pads (<NUM>) disposed in a staging array (<NUM>) at the terminal area, wherein merchant facilities (<NUM>) for preparing packages for delivery by the UAVs are disposed about a periphery of the staging array;
relocating (<NUM>) the UAVs under their own propulsion from interior charging pads of the staging array to peripheral loading pads of the staging array as the peripheral loading pads become available and the UAVs are deemed sufficiently charged and ready for delivery missions;
characterised in that:
in response to one of the merchant facilities indicating that a first package of the packages is ready for delivery, identifying (<NUM>) to a merchant attendant (<NUM>) a first UAV of the UAVs disposed on one of the peripheral loading pads assigned to accept the first package for delivery; and
synchronizing (<NUM>) a takeoff of the first UAV with an approach of the merchant attendant that loads the first UAV with the first package.