Patent Publication Number: US-2023144864-A1

Title: Loading structure with tether guide for unmanned aerial vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 17/100,930, filed Nov. 22, 2020, which is a continuation of U.S. patent application Ser. No. 16/005,288, filed Jun. 11, 2018, now U.S. Pat. No. 10,875,648, the entire contents of which are herein incorporated by reference. 
    
    
     BACKGROUND 
     An unmanned vehicle, which may also be referred to as an autonomous vehicle, includes a vehicle capable of travel without a physically-present human operator. An unmanned vehicle may operate in a remote-control mode, in an autonomous mode, or in a partially autonomous mode. 
     When an unmanned vehicle operates in a remote-control mode, a pilot or driver that is at a remote location can control the unmanned vehicle via commands that are sent to the unmanned vehicle via a wireless link. When the unmanned vehicle operates in autonomous mode, the unmanned vehicle typically moves based on pre-programmed navigation waypoints, dynamic automation systems, or a combination of these. Further, some unmanned vehicles can operate in both a remote-control mode and an autonomous mode, and in some instances may do so simultaneously. For instance, a remote pilot or driver may wish to leave navigation to an autonomous system while manually performing another task, such as operating a mechanical system for picking up objects, as an example. 
     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. Examples include quad-copters and tail-sitter unmanned aerial vehicles, among others. Unmanned vehicles also exist for hybrid operations in which multi-environment operation is possible. Examples of hybrid unmanned vehicles include an amphibious craft that is capable of operation on land as well as on water or a floatplane that is capable of landing on water as well as on land. Other examples are also possible. 
     Unmanned aerial vehicles (UAVs) may be used to deliver a payload to, or retrieve a payload from, an individual or business. Additional systems at the point of delivery or pick-up are helpful for users, workers, merchants and others to utilize and interact with UAVs. Loading systems and structures that facilitate safe and efficient delivery and/or pick-up of payloads are disclosed herein. 
     SUMMARY 
     The present application discloses unmanned aerial vehicle (UAV) payload loading systems, structures, and methods relating thereto. UAVs are increasingly utilized for a wide array of delivery services and as such, dedicated structures that increase the ease of use, efficiency, and safety of such delivery services is necessary. For example, a payload loading system designed to interact with an approaching or departing UAV associated with a delivery service may facilitate better access to loading a payload to, or unloading a payload from, the UAV. Moreover, additional components may be included as part of the payload loading system to further support the UAV delivery service. 
     Example payload loading systems described herein may be installed on freestanding support structures, may be installed on or within existing structures such as building walls, rooftops, trucks, lamp posts, cell towers, warehouses, etc., or may be installed by modifying an existing structure with aspects described herein. Beneficially, the payload loading systems described herein may be installed in a variety of locations without impeding everyday life of merchants, customers, or other people, while increasing the efficiency of access to UAV delivery service to the same merchants, customers, or other people. 
     In one embodiment, a payload loading system is described. The payload loading system includes a UAV and a loading structure, among other potential components. The UAV includes a retractable tether. A payload coupling apparatus is coupled to a distal end of the tether and the UAV is coupled to a proximate end of the tether. The tether may be extended or retracted by a winch system of the UAV such that the payload coupling apparatus is lowered down away from the UAV or raised up towards the UAV. A payload is loaded to, unloaded from, or both unloaded from and then another payload is loaded to the UAV by coupling the payload to the payload coupling apparatus. The loading structure of the payload loading system includes a landing platform and a tether guide. The tether guide is coupled to the landing platform and directs the tether as the UAV approaches and travels across at least a portion of the landing platform such that the payload coupling apparatus arrives at a target location. Moreover, the UAV may land on and move across or hover over the landing platform as the UAV travels across at least a portion of the landing platform. The payload is loaded to and/or unloaded from the payload coupling apparatus while the payload coupling apparatus is within the target location. The landing platform may include a channel that also guides the tether such that the payload coupling apparatus arrives at the target location. In some embodiments, the channel may be attached to or a component of the tether guide. 
     In another embodiment, a payload loading structure is provided. The payload loading structure includes a landing platform for a UAV and a tether guide. The UAV includes a retractable tether. The tether is coupled to a payload coupling apparatus. A payload may be attachable to the payload coupling apparatus. The tether guide is coupled to the landing platform and directs the tether such that the payload coupling apparatus arrives at a target location. The payload is loaded to and/or unloaded from the payload coupling apparatus at the target location. 
     In yet another embodiment, a method is described. The method includes the UAV traveling across at least a portion of a landing platform coupled to a loading structure. The method also includes guiding a tether of the UAV such that a payload coupling apparatus arrives at a target location. The tether is coupled to the UAV at a proximate end of the tether while the payload coupling apparatus is coupled to a distal end of the tether. The tether is guided by a tether guide coupled to the loading structure. The method further includes loading a payload to the UAV by coupling the payload to the payload coupling apparatus while the payload coupling apparatus is within the target location. In additional embodiments the method may include other aspects. 
     In further embodiments, any type of system or device could be used or configured as a means for performing functions of any of the methods described herein (or any portions of the methods described herein). For example, a system to load or unload a payload includes means to guide the tether such that the payload coupling apparatus reaches the target location. 
     These as well as other aspects, advantages, and alternatives will become apparent to those of ordinary skill in the art by reading the following detailed description, with reference where appropriate to the accompanying drawings. Further, it should be understood that the description provided in this summary section and elsewhere in this document is intended to illustrate the claimed subject matter by way of example and not by way of limitation 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is a simplified illustration of an unmanned aerial vehicle (UAV), according to an example embodiment. 
         FIG.  1 B  is a simplified illustration of a UAV, according to an example embodiment. 
         FIG.  1 C  is a simplified illustration of a UAV, according to an example embodiment. 
         FIG.  1 D  is a simplified illustration of a UAV, according to an example embodiment. 
         FIG.  1 E  is a simplified illustration of a UAV, according to an example embodiment. 
         FIG.  2    is a simplified block diagram illustrating components of an unmanned aerial vehicle, according to an example embodiment. 
         FIG.  3    is a simplified block diagram illustrating a UAV system, according to an example embodiment. 
         FIG.  4 A  depicts a payload loading system, according to an example embodiment. 
         FIG.  4 B  depicts a payload loading system, according to an example embodiment. 
         FIG.  4 C  depicts a payload loading system, according to an example embodiment. 
         FIG.  5    depicts a payload loading system, according to an example embodiment. 
         FIG.  6 A  depicts a payload loading system, according to an example embodiment. 
         FIG.  6 B  depicts a payload loading system, according to an example embodiment. 
         FIG.  6 C  depicts a payload loading system, according to an example embodiment. 
         FIG.  6 D  depicts a payload loading system, according to an example embodiment. 
         FIG.  7    depicts a payload loading system, according to an example embodiment. 
         FIG.  8 A  depicts a payload loading system, according to an example embodiment. 
         FIG.  8 B  depicts a payload loading system, according to an example embodiment. 
         FIG.  8 C  depicts a payload loading system, according to an example embodiment 
         FIG.  9 A  depicts further aspects of a payload loading system, according to an example embodiment. 
         FIG.  9 B  depicts further aspects of a payload loading system, according to an example embodiment 
         FIG.  10    depicts a payload loading system, according to an example embodiment. 
         FIG.  11    depicts a payload loading system, according to an example embodiment. 
         FIG.  12    is a simplified block diagram illustrating a method relating to a payload loading system, according to an example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Example methods, systems, and devices are described herein. Any example embodiment or feature described herein is not necessarily to be construed as preferred or advantageous over other embodiments or features. The example embodiments described herein are not meant to be limiting. It will be readily understood that certain aspects of the disclosed systems and methods can be arranged and combined in a wide variety of different configurations, all of which are contemplated herein. 
     Furthermore, the particular arrangements shown in the Figures should not be viewed as limiting. It should be understood that other embodiments might include more or less of each element shown in a given Figure. Further, some of the illustrated elements may be combined or omitted. Yet further, an example embodiment may include elements that are not illustrated in the Figures. 
     I. Overview 
     The embodiments described herein relate to payload loading structures for unmanned aerial vehicles (UAVs). Aspects written in term of “loading,” such as a payload loading structure, should be understood to not be limiting to “loading” functions or scenarios only. For example, unloading, maintenance, charging, and other interactions between a user, a UAV, a payload loading structure, or related components may occur at a payload loading structure or aspect thereof. 
     Exemplary embodiments may include, be implemented as part of, or take of the form of an aerial vehicle or system related thereto. In example embodiments, a UAV may include rotor units operable to provide thrust or lift for the UAV for transport and delivery of a payload. Herein, the terms “unmanned aerial vehicle” and “UAV” refer to any autonomous or semi-autonomous vehicle that is capable of performing some functions without a physically present human pilot. A UAV can take various forms. For example, a UAV may take the form of a fixed-wing aircraft, a glider aircraft, a tail-sitter aircraft, a jet aircraft, a ducted fan aircraft, a lighter-than-air dirigible such as a blimp or steerable balloon, a rotorcraft such as a helicopter or multicopter, and/or an ornithopter, among other possibilities. Further, the terms “drone,” “unmanned aerial vehicle system” (UAVS), or “unmanned aerial system” (UAS) may also be used to refer to a UAV. 
     UAVs are increasingly being utilized to retrieve, carry, and deliver payloads across a variety of industries. As such, infrastructure is needed at pick-up and drop-off locations so that merchants, customers, and other users can utilize UAV delivery services. More particularly, payload loading systems may provide known, accessible, dedicated, and safe areas for a person or other device utilizing a UAV delivery service to load or unload a payload. Payload loading systems may include a loading structure that further includes a landing platform and a tether guide. 
     Advantageously, payload loading systems guide a tether so that the payload coupling apparatus, which is the point of interaction with the person or device loading a payload to the UAV, arrives at a target location. The target location includes an ergonomic location such that the payload coupling apparatus is accessible for a user. By developing the payload loading system that focuses on locating the payload coupling apparatus within the target location, less concern over the exact location and orientation (or heading) of the UAV is required. The tether guide provides the means to locate the payload coupling apparatus within the target location no matter the orientation or heading of the UAV. Thus, the UAV loading/unloading process does not require exact precision from the UAV controls, but instead a loading structure of the payload loading system makes up for an amount of error or imprecision in the controls, whether it be user or computer driven. 
     The advancement of payload loading systems also provides additional functionality to loading and unloading control schemes. For example, payload loading systems described herein do not require the UAV to land on a landing platform. The UAV may hover and pass over the loading structure and so long as the tether extended below the UAV is within a predetermined range, the tether guide will direct or steer the tether such that the payload coupling apparatuses arrives at the target location, rather than the UAV having to land at a precise location with a precise orientation. 
     While landing on the platform is not required, the payload loading system more easily locates the payload coupling apparatus at the target location if the UAV does land on a landing platform of the loading structure, for example. The landing platform may provide the means for the UAV to complete a variety of other tasks such as recharging or replacing batteries and uploading or downloading information from a network, among other possibilities, when the UAV lands. 
     Beneficially, payload loading systems, as described, may provide more people with access to UAV delivery services. Additionally, elevated landing platforms and tether guides as part of the loading structure may reduce the risk of injury to humans by increasing the distance between the UAV and the point of interaction (i.e., loading and unloading of a payload at the target location). Moreover, inherent features of the payload loading systems may allow for installation of such systems (or related devices and components thereof) in a variety of locations without impeding everyday life of people. 
     The Figures described in detail below are for illustrative purposes only and may not reflect all components or connections. Further, as illustrations the Figures may not reflect actual operating conditions, but are merely to illustrate embodiments described. Further still, the relative dimensions and angles in the Figures may not be to scale, but are merely to illustrate the embodiments described. 
     II. Illustrative Unmanned Vehicles 
       FIG.  1 A  is an isometric view of an example UAV  100 . UAV  100  includes wing  102 , booms  104 , and a fuselage  106 . Wings  102  may be stationary and may generate lift based on the wing shape and the UAV&#39;s forward airspeed. For instance, the two wings  102  may have an airfoil-shaped cross section to produce an aerodynamic force on UAV  100 . In some embodiments, wing  102  may carry horizontal propulsion units  108 , and booms  104  may carry vertical propulsion units  110 . In operation, power for the propulsion units may be provided from a battery compartment  112  of fuselage  106 . In some embodiments, fuselage  106  also includes an avionics compartment  114 , an additional battery compartment (not shown) and/or a delivery unit (not shown, e.g., a winch system) for handling the payload. In some embodiments, fuselage  106  is modular, and two or more compartments (e.g., battery compartment  112 , avionics compartment  114 , other payload and delivery compartments) are detachable from each other and securable to each other (e.g., mechanically, magnetically, or otherwise) to contiguously form at least a portion of fuselage  106 . 
     In some embodiments, booms  104  terminate in rudders  116  for improved yaw control of UAV  100 . Further, wings  102  may terminate in wing tips  117  for improved control of lift of the UAV. 
     In the illustrated configuration, UAV  100  includes a structural frame. The structural frame may be referred to as a “structural H-frame” or an “H-frame” (not shown) of the UAV. The H-frame may include, within wings  102 , a wing spar (not shown) and, within booms  104 , boom carriers (not shown). In some embodiments the wing spar and the boom carriers may be made of carbon fiber, hard plastic, aluminum, light metal alloys, or other materials. The wing spar and the boom carriers may be connected with clamps. The wing spar may include pre-drilled holes for horizontal propulsion units  108 , and the boom carriers may include pre-drilled holes for vertical propulsion units  110 . 
     In some embodiments, fuselage  106  may be removably attached to the H-frame (e.g., attached to the wing spar by clamps, configured with grooves, protrusions or other features to mate with corresponding H-frame features, etc.). In other embodiments, fuselage  106  similarly may be removably attached to wings  102 . The removable attachment of fuselage  106  may improve quality and or modularity of UAV  100 . For example, electrical/mechanical components and/or subsystems of fuselage  106  may be tested separately from, and before being attached to, the H-frame. Similarly, printed circuit boards (PCBs)  118  may be tested separately from, and before being attached to, the boom carriers, therefore eliminating defective parts/subassemblies prior to completing the UAV. For example, components of fuselage  106  (e.g., avionics, battery unit, delivery units, an additional battery compartment, etc.) may be electrically tested before fuselage  106  is mounted to the H-frame. Furthermore, the motors and the electronics of PCBs  118  may also be electrically tested before the final assembly. Generally, the identification of the defective parts and subassemblies early in the assembly process lowers the overall cost and lead time of the UAV. Furthermore, different types/models of fuselage  106  may be attached to the H-frame, therefore improving the modularity of the design. Such modularity allows these various parts of UAV  100  to be upgraded without a substantial overhaul to the manufacturing process. 
     In some embodiments, a wing shell and boom shells may be attached to the H-frame by adhesive elements (e.g., adhesive tape, double-sided adhesive tape, glue, etc.). Therefore, multiple shells may be attached to the H-frame instead of having a monolithic body sprayed onto the H-frame. In some embodiments, the presence of the multiple shells reduces the stresses induced by the coefficient of thermal expansion of the structural frame of the UAV. As a result, the UAV may have better dimensional accuracy and/or improved reliability. 
     Moreover, in at least some embodiments, the same H-frame may be used with the wing shell and/or boom shells having different size and/or design, therefore improving the modularity and versatility of the UAV designs. The wing shell and/or the boom shells may be made of relatively light polymers (e.g., closed cell foam) covered by the harder, but relatively thin, plastic skins. 
     The power and/or control signals from fuselage  106  may be routed to PCBs  118  through cables running through fuselage  106 , wings  102 , and booms  104 . In the illustrated embodiment, UAV  100  has four PCBs, but other numbers of PCBs are also possible. For example, UAV  100  may include two PCBs, one per the boom. The PCBs carry electronic components  119  including, for example, power converters, controllers, memory, passive components, etc. In operation, propulsion units  108  and  110  of UAV  100  are electrically connected to the PCBs. 
     Many variations on the illustrated UAV are possible. For instance, fixed-wing UAVs may include more or fewer rotor units (vertical or horizontal), and/or may utilize a ducted fan or multiple ducted fans for propulsion. Further, UAVs with more wings (e.g., an “x-wing” configuration with four wings), are also possible. Although  FIG.  1    illustrates two wings  102 , two booms  104 , two horizontal propulsion units  108 , and six vertical propulsion units  110  per boom  104 , it should be appreciated that other variants of UAV  100  may be implemented with more or less of these components. For example, UAV  100  may include four wings  102 , four booms  104 , and more or less propulsion units (horizontal or vertical). 
     Similarly,  FIG.  1 B  shows another example of a fixed-wing UAV  120 . The fixed-wing UAV  120  includes a fuselage  122 , two wings  124  with an airfoil-shaped cross section to provide lift for the UAV  120 , a vertical stabilizer  126  (or fin) to stabilize the plane&#39;s yaw (turn left or right), a horizontal stabilizer  128  (also referred to as an elevator or tailplane) to stabilize pitch (tilt up or down), landing gear  130 , and a propulsion unit  132 , which can include a motor, shaft, and propeller. 
       FIG.  1 C  shows an example of a UAV  140  with a propeller in a pusher configuration. The term “pusher” refers to the fact that a propulsion unit  142  is mounted at the back of the UAV and “pushes” the vehicle forward, in contrast to the propulsion unit being mounted at the front of the UAV. Similar to the description provided for  FIGS.  1 A and  1 B ,  FIG.  1 C  depicts common structures used in a pusher plane, including a fuselage  144 , two wings  146 , vertical stabilizers  148 , and the propulsion unit  142 , which can include a motor, shaft, and propeller. 
       FIG.  1 D  shows an example of a tail-sitter UAV  160 . In the illustrated example, the tail-sitter UAV  160  has fixed wings  162  to provide lift and allow the UAV  160  to glide horizontally (e.g., along the x-axis, in a position that is approximately perpendicular to the position shown in  FIG.  1 D ). However, the fixed wings  162  also allow the tail-sitter UAV  160  to take off and land vertically on its own. 
     For example, at a launch site, the tail-sitter UAV  160  may be positioned vertically (as shown) with its fins  164  and/or wings  162  resting on the ground and stabilizing the UAV  160  in the vertical position. The tail-sitter UAV  160  may then take off by operating its propellers  166  to generate an upward thrust (e.g., a thrust that is generally along the y-axis). Once at a suitable altitude, the tail-sitter UAV  160  may use its flaps  168  to reorient itself in a horizontal position, such that its fuselage  170  is closer to being aligned with the x-axis than the y-axis. Positioned horizontally, the propellers  166  may provide forward thrust so that the tail-sitter UAV  160  can fly in a similar manner as a typical airplane. 
     Many variations on the illustrated fixed-wing UAVs are possible. For instance, fixed-wing UAVs may include more or fewer propellers, and/or may utilize a ducted fan or multiple ducted fans for propulsion. Further, UAVs with more wings (e.g., an “x-wing” configuration with four wings), with fewer wings, or even with no wings, are also possible. 
     As noted above, some embodiments may involve other types of UAVs, in addition to or in the alternative to fixed-wing UAVs. For instance,  FIG.  1 E  shows an example of a rotorcraft that is commonly referred to as a multicopter  180 . The multicopter  180  may also be referred to as a quadcopter, as it includes four rotors  182 . It should be understood that example embodiments may involve a rotorcraft with more or fewer rotors than the multicopter  180 . For example, a helicopter typically has two rotors. Other examples with three or more rotors are possible as well. Herein, the term “multicopter” refers to any rotorcraft having more than two rotors, and the term “helicopter” refers to rotorcraft having two rotors. 
     Referring to the multicopter  180  in greater detail, the four rotors  182  provide propulsion and maneuverability for the multicopter  180 . More specifically, each rotor  182  includes blades that are attached to a motor  184 . Configured as such, the rotors  182  may allow the multicopter  180  to take off and land vertically, to maneuver in any direction, and/or to hover. Further, the pitch of the blades may be adjusted as a group and/or differentially, and may allow the multicopter  180  to control its pitch, roll, yaw, and/or altitude. 
     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 an 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 embodiments, 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 could control high level navigation decisions for a UAV, such as by 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&#39;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. 
     More generally, it should be understood that the example UAVs described herein are not intended to be limiting. Example embodiments may relate to, be implemented within, or take the form of any type of unmanned aerial vehicle. 
     III. Illustrative UAV Components 
       FIG.  2    is a simplified block diagram illustrating components of a UAV  200 , according to an example embodiment. UAV  200  may take the form of, or be similar in form to, one of the UAVs  1100   a,    120 ,  140 ,  160 , and  180  described in reference to  FIGS.  1 A- 1 E . However, UAV  200  may also take other forms. 
     UAV  200  may include various types of sensors, and may include a computing system configured to provide the functionality described herein. In the illustrated embodiment, the sensors of UAV  200  include an inertial measurement unit (IMU)  202 , ultrasonic sensor(s)  204 , and a GPS  206 , among other possible sensors and sensing systems. 
     In the illustrated embodiment, UAV  200  also includes one or more processors  208 . A processor  208  may be a general-purpose processor or a special purpose processor (e.g., digital signal processors, application specific integrated circuits, etc.). The one or more processors  208  can be configured to execute computer-readable program instructions  212  that are stored in the data storage  210  and are executable to provide the functionality of a UAV described herein. 
     The data storage  210  may include or take the form of one or more computer-readable storage media that can be read or accessed by at least one processor  208 . The one or more computer-readable storage media can include volatile and/or non-volatile storage components, such as optical, magnetic, organic or other memory or disc storage, which can be integrated in whole or in part with at least one of the one or more processors  208 . In some embodiments, the data storage  210  can be implemented using a single physical device (e.g., one optical, magnetic, organic or other memory or disc storage unit), while in other embodiments, the data storage  210  can be implemented using two or more physical devices. 
     As noted, the data storage  210  can include computer-readable program instructions  212  and perhaps additional data, such as diagnostic data of the UAV  200 . As such, the data storage  210  may include program instructions  212  to perform or facilitate some or all of the UAV functionality described herein. For instance, in the illustrated embodiment, program instructions  212  include a navigation module  214  and a tether control module  216 . 
     In some embodiments, the control system  1120  may take the form of program instructions  212  and the one or more processors  208 . 
     A. Sensors 
     In an illustrative embodiment, IMU  202  may include both an accelerometer and a gyroscope, which may be used together to determine an orientation of the UAV  200 . In particular, the accelerometer can measure the orientation of the vehicle with respect to earth, while the gyroscope measures the rate of rotation around an axis. IMUs are commercially available in low-cost, low-power packages. For instance, an IMU  202  may take the form of or include a miniaturized MicroElectroMechanical System (MEMS) or a NanoElectroMechanical System (NEMS). Other types of IMUs may also be utilized. 
     An IMU  202  may include other sensors, in addition to accelerometers and gyroscopes, which may help to better determine position and/or help to increase autonomy of the UAV  200 . Two examples of such sensors are magnetometers and pressure sensors. In some embodiments, a UAV may include a low-power, digital 3-axis magnetometer, which can be used to realize an orientation independent electronic compass for accurate heading information. However, other types of magnetometers may be utilized as well. Other examples are also possible. Further, note that a UAV could include some or all of the above-described inertia sensors as separate components from an IMU. 
     UAV  200  may also include a pressure sensor or barometer, which can be used to determine the altitude of the UAV  200 . Alternatively, other sensors, such as sonic altimeters or radar altimeters, can be used to provide an indication of altitude, which may help to improve the accuracy of and/or prevent drift of an IMU. 
     In a further aspect, UAV  200  may include one or more sensors that allow the UAV to sense objects in the environment. For instance, in the illustrated embodiment, UAV  200  includes ultrasonic sensor(s)  204 . Ultrasonic sensor(s)  204  can determine the distance to an object by generating sound waves and determining the time interval between transmission of the wave and receiving the corresponding echo off an object. A typical application of an ultrasonic sensor for unmanned vehicles or IMUs is low-level altitude control and obstacle avoidance. An ultrasonic sensor can also be used for vehicles that need to hover at a certain height or need to be capable of detecting obstacles. Other systems can be used to determine, sense the presence of, and/or determine the distance to nearby objects, such as a light detection and ranging (LIDAR) system, laser detection and ranging (LADAR) system, and/or an infrared or forward-looking infrared (FLIR) system, among other possibilities. 
     In some embodiments, UAV  200  may also include one or more imaging system(s). For example, one or more still and/or video cameras may be utilized by UAV  200  to capture image data from the UAV&#39;s environment. As a specific example, charge-coupled device (CCD) cameras or complementary metal-oxide-semiconductor (CMOS) cameras can be used with unmanned vehicles. Such imaging sensor(s) have numerous possible applications, such as obstacle avoidance, localization techniques, ground tracking for more accurate navigation (e.g., by applying optical flow techniques to images), video feedback, and/or image recognition and processing, among other possibilities. 
     UAV  200  may also include a GPS receiver  206 . The GPS receiver  206  may be configured to provide data that is typical of well-known GPS systems, such as the GPS coordinates of the UAV  200 . Such GPS data may be utilized by the UAV  200  for various functions. As such, the UAV may use its GPS receiver  206  to help navigate to the caller&#39;s location, as indicated, at least in part, by the GPS coordinates provided by their mobile device. Other examples are also possible. 
     B. Navigation and Location Determination 
     The navigation module  214  may provide functionality that allows the UAV  200  to, e.g., move about its environment and reach a desired location. To do so, the navigation module  214  may control the altitude and/or direction of flight by controlling the mechanical features of the UAV that affect flight (e.g., its rudder(s), elevator(s), aileron(s), and/or the speed of its propeller(s)). 
     In order to navigate the UAV  200  to a target location, the navigation module  214  may implement various navigation techniques, such as map-based navigation and localization-based navigation, for instance. With map-based navigation, the UAV  200  may be provided with a map of its environment, which may then be used to navigate to a particular location on the map. With localization-based navigation, the UAV  200  may be capable of navigating in an unknown environment using localization. Localization-based navigation may involve the UAV  200  building its own map of its environment and calculating its position within the map and/or the position of objects in the environment. For example, as a UAV  200  moves throughout its environment, the UAV  200  may continuously use localization to update its map of the environment. This continuous mapping process may be referred to as simultaneous localization and mapping (SLAM). Other navigation techniques may also be utilized. 
     In some embodiments, the navigation module  214  may navigate using a technique that relies on waypoints. In particular, waypoints are sets of coordinates that identify points in physical space. For instance, an air-navigation waypoint may be defined by a certain latitude, longitude, and altitude. Accordingly, navigation module  214  may cause UAV  200  to move from waypoint to waypoint, in order to ultimately travel to a final destination (e.g., a final waypoint in a sequence of waypoints). 
     In a further aspect, the navigation module  214  and/or other components and systems of the UAV  200  may be configured for “localization” to more precisely navigate to the scene of a target location. More specifically, it may be desirable in certain situations for a UAV to be within a threshold distance of the target location where a payload  228  is being delivered by a UAV (e.g., within a few feet of the target destination). To this end, a UAV may use a two-tiered approach in which it uses a more-general location-determination technique to navigate to a general area that is associated with the target location, and then use a more-refined location-determination technique to identify and/or navigate to the target location within the general area. 
     For example, the UAV  200  may navigate to the general area of a target destination where a payload  228  is being delivered using waypoints and/or map-based navigation. The UAV may then switch to a mode in which it utilizes a localization process to locate and travel to a more specific location. For instance, if the UAV  200  is to deliver a payload to a user&#39;s home, the UAV  200  may need to be substantially close to the target location in order to avoid delivery of the payload to undesired areas (e.g., onto a roof, into a pool, onto a neighbor&#39;s property, etc.). However, a GPS signal may only get the UAV  200  so far (e.g., within a block of the user&#39;s home). A more precise location-determination technique may then be used to find the specific target location. 
     Various types of location-determination techniques may be used to accomplish localization of the target delivery location once the UAV  200  has navigated to the general area of the target delivery location. For instance, the UAV  200  may be equipped with one or more sensory systems, such as, for example, ultrasonic sensors  204 , infrared sensors (not shown), and/or other sensors, which may provide input that the navigation module  214  utilizes to navigate autonomously or semi-autonomously to the specific target location. 
     As another example, once the UAV  200  reaches the general area of the target delivery location (or of a moving subject such as a person or their mobile device), the UAV  200  may switch to a “fly-by-wire” mode where it is controlled, at least in part, by a remote operator, who can navigate the UAV  200  to the specific target location. To this end, sensory data from the UAV  200  may be sent to the remote operator to assist them in navigating the UAV  200  to the specific location. 
     As yet another example, the UAV  200  may include a module that is able to signal to a passer-by for assistance in either reaching the specific target delivery location; for example, the UAV  200  may display a visual message requesting such assistance in a graphic display, play an audio message or tone through speakers to indicate the need for such assistance, among other possibilities. Such a visual or audio message might indicate that assistance is needed in delivering the UAV  200  to a particular person or a particular location, and might provide information to assist the passer-by in delivering the UAV  200  to the person or location (e.g., a description or picture of the person or location, and/or the person or location&#39;s name), among other possibilities. Such a feature can be useful in a scenario in which the UAV is unable to use sensory functions or another location-determination technique to reach the specific target location. However, this feature is not limited to such scenarios. 
     In some embodiments, once the UAV  200  arrives at the general area of a target delivery location, the UAV  200  may utilize a beacon from a user&#39;s remote device (e.g., the user&#39;s mobile phone) to locate the person. Such a beacon may take various forms. As an example, consider the scenario where a remote device, such as the mobile phone of a person who requested a UAV delivery, is able to send out directional signals (e.g., via an RF signal, a light signal and/or an audio signal). In this scenario, the UAV  200  may be configured to navigate by “sourcing” such directional signals—in other words, by determining where the signal is strongest and navigating accordingly. As another example, a mobile device can emit a frequency, either in the human range or outside the human range, and the UAV  200  can listen for that frequency and navigate accordingly. As a related example, if the UAV  200  is listening for spoken commands, then the UAV  200  could utilize spoken statements, such as “I&#39;m over here!” to source the specific location of the person requesting delivery of a payload. 
     In an alternative arrangement, a navigation module may be implemented at a remote computing device, which communicates wirelessly with the UAV  200 . The remote computing device may receive data indicating the operational state of the UAV  200 , sensor data from the UAV  200  that allows it to assess the environmental conditions being experienced by the UAV  200 , and/or location information for the UAV  200 . Provided with such information, the remote computing device may determine altitudinal and/or directional adjustments that should be made by the UAV  200  and/or may determine how the UAV  200  should adjust its mechanical features (e.g., its rudder(s), elevator(s), aileron(s), and/or the speed of its propeller(s)) in order to effectuate such movements. The remote computing system may then communicate such adjustments to the UAV  200  so it can move in the determined manner. 
     C. Communication Systems 
     In a further aspect, the UAV  200  includes one or more communication systems  218 . The communications systems  218  may include one or more wireless interfaces and/or one or more wireline interfaces, which allow the UAV  200  to communicate via one or more networks. Such wireless interfaces may provide for communication under one or more wireless communication protocols, such as Bluetooth, WiFi (e.g., an IEEE 802.11 protocol), Long-Term Evolution (LTE), WiMAX (e.g., an IEEE 802.16 standard), a radio-frequency ID (RFID) protocol, near-field communication (NFC), and/or other wireless communication protocols. Such wireline interfaces may include an Ethernet interface, a Universal Serial Bus (USB) interface, or similar interface to communicate via a wire, a twisted pair of wires, a coaxial cable, an optical link, a fiber-optic link, or other physical connection to a wireline network. 
     In some embodiments, a UAV  200  may include communication systems  218  that allow for both short-range communication and long-range communication. For example, the UAV  200  may be configured for short-range communications using Bluetooth and for long-range communications under a CDMA protocol. In such an embodiment, the UAV  200  may be configured to function as a “hot spot;” or in other words, as a gateway or proxy between a remote support device and one or more data networks, such as a cellular network and/or the Internet. Configured as such, the UAV  200  may facilitate data communications that the remote support device would otherwise be unable to perform by itself. 
     For example, the UAV  200  may provide a WiFi connection to a remote device, and serve as a proxy or gateway to a cellular service provider&#39;s data network, which the UAV might connect to under an LTE or a 3G protocol, for instance. The UAV  200  could also serve as a proxy or gateway to a high-altitude balloon network, a satellite network, or a combination of these networks, among others, which a remote device might not be able to otherwise access. 
     D. Power Systems 
     In a further aspect, the UAV  200  may include power system(s)  220 . The power system  220  may include one or more batteries for providing power to the UAV  200 . In one example, the one or more batteries may be rechargeable and each battery may be recharged via a wired connection between the battery and a power supply and/or via a wireless charging system, such as an inductive charging system that applies an external time-varying magnetic field to an internal battery. 
     E. Payload Delivery 
     The UAV  200  may employ various systems and configurations in order to transport and deliver a payload  228 . In some implementations, the payload  228  of a given UAV  200  may include or take the form of a “package” designed to transport various goods to a target delivery location. For example, the UAV  200  can include a compartment, in which an item or items may be transported. Such a package may one or more food items, purchased goods, medical items, or any other object(s) having a size and weight suitable to be transported between two locations by the UAV. In other embodiments, a payload  228  may simply be the one or more items that are being delivered (e.g., without any package housing the items). 
     In some embodiments, the payload  228  may be attached to the UAV and located substantially outside of the UAV during some or all of a flight by the UAV. For example, the package may be tethered or otherwise releasably attached below the UAV during flight to a target location. In an embodiment where a package carries goods below the UAV, the package may include various features that protect its contents from the environment, reduce aerodynamic drag on the system, and prevent the contents of the package from shifting during UAV flight. 
     For instance, when the payload  228  takes the form of a package for transporting items, the package may include an outer shell constructed of water-resistant cardboard, plastic, or any other lightweight and water-resistant material. Further, in order to reduce drag, the package may feature smooth surfaces with a pointed front that reduces the frontal cross-sectional area. Further, the sides of the package may taper from a wide bottom to a narrow top, which allows the package to serve as a narrow pylon that reduces interference effects on the wing(s) of the UAV. This may move some of the frontal area and volume of the package away from the wing(s) of the UAV, thereby preventing the reduction of lift on the wing(s) cause by the package. Yet further, in some embodiments, the outer shell of the package may be constructed from a single sheet of material in order to reduce air gaps or extra material, both of which may increase drag on the system. Additionally or alternatively, the package may include a stabilizer to dampen package flutter. This reduction in flutter may allow the package to have a less rigid connection to the UAV and may cause the contents of the package to shift less during flight. 
     In order to deliver the payload, the UAV may include a winch system  221  controlled by the tether control module  216  in order to lower the payload  228  to the ground while the UAV hovers above. As shown in  FIG.  2   , the winch system  221  may include a tether  224 , and the tether  224  may be coupled to the payload  228  by a payload coupling apparatus  226 . The tether  224  may be wound on a spool that is coupled to a motor  222  of the UAV. The motor  222  may take the form of a DC motor (e.g., a servo motor) that can be actively controlled by a speed controller. The tether control module  216  can control the speed controller to cause the motor  222  to rotate the spool, thereby unwinding or retracting the tether  224  and lowering or raising the payload coupling apparatus  226 . In practice, the speed controller may output a desired operating rate (e.g., a desired RPM) for the spool, which may correspond to the speed at which the tether  224  and payload  228  should be lowered towards the ground. The motor  222  may then rotate the spool so that it maintains the desired operating rate. 
     In order to control the motor  222  via the speed controller, the tether control module  216  may receive data from a speed sensor (e.g., an encoder) configured to convert a mechanical position to a representative analog or digital signal. In particular, the speed sensor may include a rotary encoder that may provide information related to rotary position (and/or rotary movement) of a shaft of the motor or the spool coupled to the motor, among other possibilities. Moreover, the speed sensor may take the form of an absolute encoder and/or an incremental encoder, among others. So in an example implementation, as the motor  222  causes rotation of the spool, a rotary encoder may be used to measure this rotation. In doing so, the rotary encoder may be used to convert a rotary position to an analog or digital electronic signal used by the tether control module  216  to determine the amount of rotation of the spool from a fixed reference angle and/or to an analog or digital electronic signal that is representative of a new rotary position, among other options. Other examples are also possible. 
     Based on the data from the speed sensor, the tether control module  216  may determine a rotational speed of the motor  222  and/or the spool and responsively control the motor  222  (e.g., by increasing or decreasing an electrical current supplied to the motor  222 ) to cause the rotational speed of the motor  222  to match a desired speed. When adjusting the motor current, the magnitude of the current adjustment may be based on a proportional-integral-derivative (PID) calculation using the determined and desired speeds of the motor  222 . For instance, the magnitude of the current adjustment may be based on a present difference, a past difference (based on accumulated error over time), and a future difference (based on current rates of change) between the determined and desired speeds of the spool. 
     In some embodiments, the tether control module  216  may vary the rate at which the tether  224  and payload  228  are lowered to the ground. For example, the speed controller may change the desired operating rate according to a variable deployment-rate profile and/or in response to other factors in order to change the rate at which the payload  228  descends toward the ground. To do so, the tether control module  216  may adjust an amount of braking or an amount of friction that is applied to the tether  224 . For example, to vary the tether deployment rate, the UAV  200  may include friction pads that can apply a variable amount of pressure to the tether  224 . As another example, the UAV  200  can include a motorized braking system that varies the rate at which the spool lets out the tether  224 . Such a braking system may take the form of an electromechanical system in which the motor  222  operates to slow the rate at which the spool lets out the tether  224 . Further, the motor  222  may vary the amount by which it adjusts the speed (e.g., the RPM) of the spool, and thus may vary the deployment rate of the tether  224 . Other examples are also possible. 
     In some embodiments, the tether control module  216  may be configured to limit the motor current supplied to the motor  222  to a maximum value. With such a limit placed on the motor current, there may be situations where the motor  222  cannot operate at the desired operate specified by the speed controller. For instance, as discussed in more detail below, there may be situations where the speed controller specifies a desired operating rate at which the motor  222  should retract the tether  224  toward the UAV  200 , but the motor current may be limited such that a large enough downward force on the tether  224  would counteract the retracting force of the motor  222  and cause the tether  224  to unwind instead. And as further discussed below, a limit on the motor current may be imposed and/or altered depending on an operational state of the UAV  200 . 
     In some embodiments, the tether control module  216  may be configured to determine a status of the tether  224  and/or the payload  228  based on the amount of current supplied to the motor  222 . For instance, if a downward force is applied to the tether  224  (e.g., if the payload  228  is attached to the tether  224  or if the tether  224  gets snagged on an object when retracting toward the UAV  200 ), the tether control module  216  may need to increase the motor current in order to cause the determined rotational speed of the motor  222  and/or spool to match the desired speed. Similarly, when the downward force is removed from the tether  224  (e.g., upon delivery of the payload  228  or removal of a tether snag), the tether control module  216  may need to decrease the motor current in order to cause the determined rotational speed of the motor  222  and/or spool to match the desired speed. As such, the tether control module  216  may, based on the current supplied to the motor  222 , determine if the payload  228  is attached to the tether  224 , if someone or something is pulling on the tether  224 , and/or if the payload coupling apparatus  226  is pressing against the UAV  200  after retracting the tether  224 . Other examples are possible as well. 
     During delivery of the payload  228 , the payload coupling apparatus  226  can be configured to secure the payload  228  while being lowered from the UAV by the tether  224 , and can be further configured to release the payload  228  upon reaching ground level. The payload coupling apparatus  226  can then be retracted to the UAV by reeling in the tether  224  using the motor  222 . 
     In some implementations, the payload  228  may be passively released once it is lowered to the ground. For example, a passive release mechanism may include one or more swing arms adapted to retract into and extend from a housing. An extended swing arm may form a hook on which the payload  228  may be attached. Upon lowering the release mechanism and the payload  228  to the ground via a tether, a gravitational force as well as a downward inertial force on the release mechanism may cause the payload  228  to detach from the hook allowing the release mechanism to be raised upwards toward the UAV. The release mechanism may further include a spring mechanism that biases the swing arm to retract into the housing when there are no other external forces on the swing arm. For instance, a spring may exert a force on the swing arm that pushes or pulls the swing arm toward the housing such that the swing arm retracts into the housing once the weight of the payload  228  no longer forces the swing arm to extend from the housing. Retracting the swing arm into the housing may reduce the likelihood of the release mechanism snagging the payload  228  or other nearby objects when raising the release mechanism toward the UAV upon delivery of the payload  228 . 
     Active payload release mechanisms are also possible. For example, sensors such as a barometric pressure based altimeter and/or accelerometers may help to detect the position of the release mechanism (and the payload) relative to the ground. Data from the sensors can be communicated back to the UAV and/or a control system over a wireless link and used to help in determining when the release mechanism has reached ground level (e.g., by detecting a measurement with the accelerometer that is characteristic of ground impact). In other examples, the UAV may determine that the payload has reached the ground based on a weight sensor detecting a threshold low downward force on the tether and/or based on a threshold low measurement of power drawn by the winch when lowering the payload. 
     Other systems and techniques for delivering a payload, in addition or in the alternative to a tethered delivery system are also possible. For example, a UAV  200  could include an air-bag drop system or a parachute drop system. Alternatively, a UAV  200  carrying a payload could simply land on the ground at a delivery location. Other examples are also possible. 
     IV. Illustrative UAV Deployment Systems 
     UAV systems may be implemented in order to provide various UAV-related services. In particular, UAVs may be provided at a number of different launch sites that may be in communication with regional and/or central control systems. Such a distributed UAV system may allow UAVs to be quickly deployed to provide services across a large geographic area (e.g., that is much larger than the flight range of any single UAV). For example, UAVs capable of carrying payloads may be distributed at a number of launch sites across a large geographic area (possibly even throughout an entire country, or even worldwide), in order to provide on-demand transport of various items to locations throughout the geographic area.  FIG.  3    is a simplified block diagram illustrating a distributed UAV system  300 , according to an example embodiment. 
     In the illustrative UAV system  300 , an access system  302  may allow for interaction with, control of, and/or utilization of a network of UAVs  304 . In some embodiments, an access system  302  may be a computing system that allows for human-controlled dispatch of UAVs  304 . As such, the control system may include or otherwise provide a user interface through which a user can access and/or control the UAVs  304 . 
     In some embodiments, dispatch of the UAVs  304  may additionally or alternatively be accomplished via one or more automated processes. For instance, the access system  302  may dispatch one of the UAVs  304  to transport a payload to a target location, and the UAV may autonomously navigate to the target location by utilizing various on-board sensors, such as a GPS receiver and/or other various navigational sensors. 
     Further, the access system  302  may provide for remote operation of a UAV. For instance, the access system  302  may allow an operator to control the flight of a UAV via its user interface. As a specific example, an operator may use the access system  302  to dispatch a UAV  304  to a target location. The UAV  304  may then autonomously navigate to the general area of the target location. At this point, the operator may use the access system  302  to take control of the UAV  304  and navigate the UAV to the target location (e.g., to a particular person to whom a payload is being transported). Other examples of remote operation of a UAV are also possible. 
     In an illustrative embodiment, the UAVs  304  may take various forms. For example, each of the UAVs  304  may be a UAV such as those illustrated in  FIGS.  1 A- 1 E . However, UAV system  300  may also utilize other types of UAVs without departing from the scope of the invention. In some implementations, all of the UAVs  304  may be of the same or a similar configuration. However, in other implementations, the UAVs  304  may include a number of different types of UAVs. For instance, the UAVs  304  may include a number of types of UAVs, with each type of UAV being configured for a different type or types of payload delivery capabilities. 
     The UAV system  300  may further include a remote device  306 , which may take various forms. Generally, the remote device  306  may be any device through which a direct or indirect request to dispatch a UAV can be made. (Note that an indirect request may involve any communication that may be responded to by dispatching a UAV, such as requesting a package delivery). In an example embodiment, the remote device  306  may be a mobile phone, tablet computer, laptop computer, personal computer, or any network-connected computing device. Further, in some instances, the remote device  306  may not be a computing device. As an example, a standard telephone, which allows for communication via plain old telephone service (POTS), may serve as the remote device  306 . Other types of remote devices are also possible. 
     Further, the remote device  306  may be configured to communicate with access system  302  via one or more types of communication network(s)  308 . For example, the remote device  306  may communicate with the access system  302  (or a human operator of the access system  302 ) by communicating over a POTS network, a cellular network, and/or a data network such as the Internet. Other types of networks may also be utilized. 
     In some embodiments, the remote device  306  may be configured to allow a user to request delivery of one or more items to a desired location. For example, a user could request UAV delivery of a package to their home via their mobile phone, tablet, or laptop. As another example, a user could request dynamic delivery to wherever they are located at the time of delivery. To provide such dynamic delivery, the UAV system  300  may receive location information (e.g., GPS coordinates, etc.) from the user&#39;s mobile phone, or any other device on the user&#39;s person, such that a UAV can navigate to the user&#39;s location (as indicated by their mobile phone). 
     In an illustrative arrangement, the central dispatch system  310  may be a server or group of servers, which is configured to receive dispatch messages requests and/or dispatch instructions from the access system  302 . Such dispatch messages may request or instruct the central dispatch system  310  to coordinate the deployment of UAVs to various target locations. The central dispatch system  310  may be further configured to route such requests or instructions to one or more local dispatch systems  312 . To provide such functionality, the central dispatch system  310  may communicate with the access system  302  via a data network, such as the Internet or a private network that is established for communications between access systems and automated dispatch systems. 
     In the illustrated configuration, the central dispatch system  310  may be configured to coordinate the dispatch of UAVs  304  from a number of different local dispatch systems  312 . As such, the central dispatch system  310  may keep track of which UAVs  304  are located at which local dispatch systems  312 , which UAVs  304  are currently available for deployment, and/or which services or operations each of the UAVs  304  is configured for (in the event that a UAV fleet includes multiple types of UAVs configured for different services and/or operations). Additionally or alternatively, each local dispatch system  312  may be configured to track which of its associated UAVs  304  are currently available for deployment and/or are currently in the midst of item transport. 
     In some cases, when the central dispatch system  310  receives a request for UAV-related service (e.g., transport of an item) from the access system  302 , the central dispatch system  310  may select a specific UAV  304  to dispatch. The central dispatch system  310  may accordingly instruct the local dispatch system  312  that is associated with the selected UAV to dispatch the selected UAV. The local dispatch system  312  may then operate its associated deployment system  314  to launch the selected UAV. In other cases, the central dispatch system  310  may forward a request for a UAV-related service to a local dispatch system  312  that is near the location where the support is requested and leave the selection of a particular UAV  304  to the local dispatch system  312 . 
     In an example configuration, the local dispatch system  312  may be implemented as a computing system at the same location as the deployment system(s)  314  that it controls. For example, the local dispatch system  312  may be implemented by a computing system installed at a building, such as a warehouse, where the deployment system(s)  314  and UAV(s)  304  that are associated with the particular local dispatch system  312  are also located. In other embodiments, the local dispatch system  312  may be implemented at a location that is remote to its associated deployment system(s)  314  and UAV(s)  304 . 
     Numerous variations on and alternatives to the illustrated configuration of the UAV system  300  are possible. For example, in some embodiments, a user of the remote device  306  could request delivery of a package directly from the central dispatch system  310 . To do so, an application may be implemented on the remote device  306  that allows the user to provide information regarding a requested delivery, and generate and send a data message to request that the UAV system  300  provide the delivery. In such an embodiment, the central dispatch system  310  may include automated functionality to handle requests that are generated by such an application, evaluate such requests, and, if appropriate, coordinate with an appropriate local dispatch system  312  to deploy a UAV. 
     Further, some or all of the functionality that is attributed herein to the central dispatch system  310 , the local dispatch system(s)  312 , the access system  302 , and/or the deployment system(s)  314  may be combined in a single system, implemented in a more complex system, and/or redistributed among the central dispatch system  310 , the local dispatch system(s)  312 , the access system  302 , and/or the deployment system(s)  314  in various ways. 
     Yet further, while each local dispatch system  312  is shown as having two associated deployment systems  314 , a given local dispatch system  312  may alternatively have more or fewer associated deployment systems  314 . Similarly, while the central dispatch system  310  is shown as being in communication with two local dispatch systems  312 , the central dispatch system  310  may alternatively be in communication with more or fewer local dispatch systems  312 . 
     In a further aspect, the deployment systems  314  may take various forms. In general, the deployment systems  314  may take the form of or include systems for physically launching one or more of the UAVs  304 . Such launch systems may include features that provide for an automated UAV launch and/or features that allow for a human-assisted UAV launch. Further, the deployment systems  314  may each be configured to launch one particular UAV  304 , or to launch multiple UAVs  304 . 
     The deployment systems  314  may further be configured to provide additional functions, including for example, diagnostic-related functions such as verifying system functionality of the UAV, verifying functionality of devices that are housed within a UAV (e.g., a payload delivery apparatus), and/or maintaining devices or other items that are housed in the UAV (e.g., by monitoring a status of a payload such as its temperature, weight, etc.). 
     In some embodiments, the deployment systems  314  and their corresponding UAVs  304  (and possibly associated local dispatch systems  312 ) may be strategically distributed throughout an area such as a city. For example, the deployment systems  314  may be strategically distributed such that each deployment system  314  is proximate to one or more payload pickup locations (e.g., near a restaurant, store, or warehouse). However, the deployment systems  314  (and possibly the local dispatch systems  312 ) may be distributed in other ways, depending upon the particular implementation. As an additional example, kiosks that allow users to transport packages via UAVs may be installed in various locations. Such kiosks may include UAV launch systems, and may allow a user to provide their package for loading onto a UAV and pay for UAV shipping services, among other possibilities. Other examples are also possible. 
     In a further aspect, the UAV system  300  may include or have access to a user-account database  316 . The user-account database  316  may include data for a number of user accounts, and which are each associated with one or more person. For a given user account, the user-account database  316  may include data related to or useful in providing UAV-related services. Typically, the user data associated with each user account is optionally provided by an associated user and/or is collected with the associated user&#39;s permission. 
     Further, in some embodiments, a person may be required to register for a user account with the UAV system  300 , if they wish to be provided with UAV-related services by the UAVs  304  from UAV system  300 . As such, the user-account database  316  may include authorization information for a given user account (e.g., a username and password), and/or other information that may be used to authorize access to a user account. 
     In some embodiments, a person may associate one or more of their devices with their user account, such that they can access the services of UAV system  300 . For example, when a person uses an associated mobile phone, e.g., to place a call to an operator of the access system  302  or send a message requesting a UAV-related service to a dispatch system, the phone may be identified via a unique device identification number, and the call or message may then be attributed to the associated user account. Other examples are also possible. 
     V. Illustrative UAV Payload Loading Systems 
       FIGS.  4 A ,  FIG.  4 B , and  FIG.  4 C  depict a payload loading system  400 , according to an example embodiment. The payload loading system  400  includes a loading structure  402  and a UAV  430 . The loading structure  402  includes a tether guide  405  and a landing platform  410 . The tether guide  405  includes a first edge  409 A and a second edge  409 B. The UAV  430  includes a retractable tether  440  and a payload coupling apparatus  450 . 
     The UAV  430  may be similar to the UAVs described in  FIGS.  1 A- 1 E ,  FIG.  2   , and  FIG.  3    above. The UAV  430  includes components not depicted in  FIGS.  4 A- 4 C . For example, the UAV  430  may further include a winch system. The winch system may be similar to winch systems described above, including winch system  221  of  FIG.  2   , for example. The winch system may include the retractable tether  440 . Other components of the UAV  430  may be similar in form and function as components described as part of the UAVs described in  FIGS.  1 A- 1 E . 
     The UAV  430  is coupled to a proximate end of the retractable tether  440 . Moreover, the proximate end of the tether  440  may be coupled to the winch system of the UAV  430 . The payload coupling apparatus  450  is coupled to the retractable tether  440  at a distal end of the tether  440 . A payload  460  is coupleable to the retractable tether  440  at the payload coupling apparatus  450 . 
     The loading structure  402  includes and defines a UAV approach opening  407 . As the UAV  430  approaches the loading structure  402 , as shown in  FIG.  4 A , if the retractable tether  440  is not already extended, the retractable tether  440  is extended from the UAV  430 . The UAV approach opening  407  is large enough to not interfere with the payload coupling apparatus  450  as the UAV  430  comes even closer and begins to travel across (either by hovering over or on) the loading structure  402  and more particularly the landing platform  410 . The tether guide  405  may direct the retractable tether  440  such that the payload coupling apparatus  450  pass through the UAV approach opening  407  while the UAV  430  approaches and travels across the landing platform  410 . 
     As the UAV  430  continues from an initial approach position in  FIG.  4 A  to the position shown in  FIG.  4 B  where the UAV  430  has approached and traveled across a portion of the landing platform  410  and is hovering over the landing platform  410  of the loading structure  402 , the tether guide  405  directs or steers the retractable tether  440  to a location where the retractable tether  440  pass through the landing platform  410 . The tether guide  405  may direct or steer the retractable tether  440  when the retractable tether  440  comes into contact with the first edge  409 A or the second edge  409 B of the tether guide  405 . The edges  409 A- 409 B may be considered edges of at least a portion of the loading structure  410 . At least a portion of the edges  409 A- 409 B may be at an elevation above or below the elevation of the landing platform  410 . Directing the retractable tether  440  includes steering or guiding the retractable tether  440  in a direction that may be different from a heading that the UAV  430  is traveling as the UAV  430  approaches and/or travels across the landing platform  410 . 
     The tether guide  405  is coupled to the landing platform  410 . Additionally, the landing platform  410  includes a channel  415 . The channel  415  is a slot in the landing platform  410 , that in some embodiments is a continuation of the tether guide  405  such that the channel  415  also directs or guides the retractable tether  440 . As such, in at least some embodiments, the tether guide  405  includes the channel  415 . In some examples, the tether guide  405  may funnel the retractable tether  440  towards the channel  415  or towards a center of the landing platform  410 . In other examples, the tether guide  405  and the channel  415  may direct the retractable tether  440  as the UAV  430  approaches and travels across at least a portion of the landing platform  410  such that the payload coupling apparatus  450  arrives at a target location  490 . In other words, as the UAV  430  travels across at least a portion of the landing platform  410  the retractable tether  440  passes through at least a portion of the channel  415  such that the payload coupling apparatus  450  arrives at the target location  490 . 
     Within some embodiments, the tether guide  405  and the channel  415  may be constructed from a low friction material. Moreover, the tether guide  405  and the channel  415  may also include one or more rollers that are configured to rotate as the retractable tether  440  comes into contact with and moves along the tether guide  405  or channel  415 . The rollers (or another aspect of the loading structure  402  in other examples) may provide feedback to the UAV  430 , an operator, or to other components of the payload loading system  400 . The feedback may include velocity, position, or other information of the UAV  430  and/or retractable tether  440 , for example. 
     While the UAV  430  is shown in  FIG.  4 B  as hovering above and having moved over a portion of the landing platform  410 , in other embodiments the UAV  430  may land on the landing platform  410  and then proceed to travel across the landing platform  410  while the UAV  430  is in contact with the landing platform  410 . Within examples, no matter if the UAV  430  lands or hovers, the landing platform  410  provides some level of environmental protection to users (humans or other devices) and the payload  460  the UAV  430  is picking up. The landing platform  410  maintains the UAV  430  a buffer distance, or safety distance, above the target location  490 . 
     The target location  490  is a three-dimensional space that is easily accessed by a user, such as a consumer or merchant. In some embodiments, the target location  490  is at an ergonomic position for a user to load or unload the payload  460 . In some regards, the target location  490  is at an ergonomic position for a user to load or unload the payload  460 . While shown as a three-dimensional rectangular box in  FIGS.  4 B and  4 C , the target location  490  may take any number of other shapes including being spherical or conical, among others. In some embodiments, the target location  490  may be a feature defined by the landing structure  402 . For example, in  FIGS.  4 B and  4 C , the target location  490  is under the landing platform  410  at a height that is readily accessible by a user, for example. Additionally, while the target location  490  provided in  FIGS.  4 B and  4 C  is relatively about the same width and length as the loading platform  410 , in other embodiments the target location  490  may be relatively smaller than the landing platform  410 . Within examples, the target location  490  may be a predetermined location known to a dispatch system as part of a UAV system (such as those described in  FIG.  3   ). GPS or other systems or signals, included as part of the loading structure  402 , and/or also onboard or transmitted to the UAV  430 , may notify that the UAV  430  is in a position such that the payload coupling apparatus  450  should be within a given target location, such as the target location  490 . 
     The payload loading system  400  may further include other features, such as notifying a user when the UAV  430  has arrived to pick up (or drop off) the payload  460 . In some embodiments, the loading structure  402  may include a user interface to assist the user in preparing for delivery or pick-up. For example, a merchant may enter an address or other user information into the payload loading system  400  such that the UAV  430  is provided with relevant information to carry out the delivery of the payload  460 . 
     In order to facilitate more efficient and simpler loading and unloading of a payload (such as payload  460 ), it is desirable for the payload coupling apparatus  450  to arrive at the target location  490  (as shown in  FIG.  4 B , for example), so that the payload  460  may be loaded to the UAV  430  via the retractable tether  440  by coupling the payload  460  to the payload coupling apparatus  450  while the payload coupling apparatus  450  is within the target location  490 . In this regard, the payload  460  may be loaded to the payload coupling apparatus at or within the target location  490 . 
     As depicted in  FIG.  4 C , the UAV  430  has landed on the landing platform  410 . While landed, the UAV  430  may charge or replace batteries, and/or communicate with other aspects of a UAV system. Additionally, while landed, the UAV  430  may wait for a user or other device to load (or unload) the payload  460  onto the payload coupling apparatus  450 . At least one advantage of the payload loading system  400  being configured to support the landing of the UAV  430  is that loading the payload  460  while the UAV  430  is landed saves battery energy of the UAV  430 . 
     When the payload  460  is loaded to the payload coupling apparatus  450 , one or more sensors on the UAV  430  may detect an increase in tension in the retractable tether  440 . The UAV  430  may then begin to depart from the loading structure  402 . This may be accomplished by beginning to hover (if not already hovering) and/or continuing to travel across the landing platform  410 . In some embodiments, the retractable tether  440  may continue to pass through the rest or the entirety of the channel  415  (and/or the tether guide  405 ) as the UAV  430  departs the loading structure  402 . Within examples, the channel  415  may be a slot that runs through the entirety of the loading platform  410 . 
     As shown in  FIGS.  4 A- 4 C , and provided in further detail below for other particular embodiments, the tether guide  405  includes at least one edge (the first edge  409 A and/or the second edge  409 B) of the loading structure  402  that guides the retractable tether  440  towards or in the direction of the target location  490  such that the payload coupling apparatus  450  is also guided towards the target location  490 . In some aspects, the tether guide  405  constrains the retractable tether  440  in at least one degree of freedom by preventing motion in that at least one direction. For example, the retractable tether  440  may contact the first edge  409 A and then the retractable tether  440  be directed or forced in a direction that is different than the heading of the UAV  430 . In some aspects, the first edge  409 A may be at an angle relative to the heading of the UAV  430 . The angle of the edge  409 A may direct the retractable tether  440  along a heading that is different than the heading of the UAV. In some embodiments, the edges  409 A- 409 B of the tether guide  405  are coupled to one or more corresponding edges of the channel  415 . So, for example, the first edge  409 A may be coupled to and continuous with an edge of the channel  415 . 
     Moreover, the tether guide  450  passively guides a direction or path of the retractable tether  440  as the UAV  430  travels across the loading structure  402 . So for example, if the UAV  430  was slightly misaligned, with slight error in heading among other possible reasons, rather than having to adjust or re-approach the loading structure  402  (or more particularly the target location  490 ), so long as the retractable tether  440  is within the UAV approach opening  407 , the tether guide  405  angled towards a middle of the target location  490  and the platform  410  (in this embodiment) will be directed or funneled such that the payload coupling apparatus  450  will arrive at the target location  490 . The UAV approach opening  407  is wider and larger than the channel  415 , so the UAV  430  does not have to get the retractable tether  440  aligned with the channel  415  on its own, but instead the tether guide  450  as a feature of the loading structure  402  will provide the additional alignment and guidance so the payload coupling apparatus  450  arrives in the target location  490 . 
     Additionally,  FIGS.  4 A- 4 C  depict an embodiment in which the tether guide  405  and the channel  415  direct or steer the retractable tether  440  such that the UAV  430  and the payload coupling apparatus  450  travel in substantially parallel headings. Furthermore, the tether guide  405  and/or channel  415  may reduce the movement of the payload coupling apparatus  450 , such any swinging or similar movement of the payload coupling apparatus  450  while the payload  460  may be loaded to the UAV  430 . 
       FIG.  5    depicts a payload loading structure  500 . The payload loading structure  500  includes a loading structure  502  and a UAV  530 . The payload loading structure  500  may include components similar to the payload loading structure  400  provided in  FIGS.  4 A- 4 C , even if those components are not explicitly labeled. Moreover, features of the payload loading structure  500  may be similar in form and function to components of the payload loading structure  400 . For example, the loading structure  502  and the UAV  530  may be similar to the loading structure  402  and the UAV  430  of  FIGS.  4 A- 4 C . 
     As illustrated in  FIG.  5   , the loading structure  502  may be a structure as part of a building or warehouse. Within examples, the loading structure  502  is coupled to, or included as part of a merchant module. The merchant module may include a warehouse or distribution center. A merchant may sell or execute deliveries out via a UAV delivery system out of the merchant module including the loading structure  502 . The loading structure  502  includes a landing platform  510 . The landing platform  510  may include at least a portion of the top or roof of the merchant module. A channel  515  may be included as part of the landing platform  510  and define a slot that extends from a UAV approach opening  507  to a UAV departure opening  508 . The channel  515  may be considered coupled to and an extension of the tether guide  505 . The UAV approach opening  507  may be sized to not interfere with a payload coupling apparatus  550  coupled to a tether  540  that is extended from the UAV  530 . The tether  540  may also be a retractable tether. The UAV departure opening  508  may be sized to not interfere with a payload coupling apparatus  550  coupled to a payload  560 . As such, in some embodiments, the UAV departure opening  508  may be larger than the UAV approach opening  507 . The UAV approach opening  507  and the UAV departure opening  508  are located within walls of the loading structure  502 . In some examples, the UAV approach opening  507  and the UAV departure opening  508  are located in the walls of a merchant module. 
     As shown in  FIG.  5   , as the UAV  530  approaches the landing platform  510  of the loading structure  502 , a tether guide  505  may direct or align the tether  540  into the channel  515 . A target location (not depicted) may include the area within the loading structure  502 , or within the merchant module, under the channel  515 . This arrangement allows a user, such as a merchant, to load the payload  560  to the payload coupling apparatus  550  as the UAV  530  travels across the loading platform  510  while the UAV  530  is maintained safely outside of the loading structure  502  (the merchant module, for example). As the UAV  530  approaches the loading structure  502 , the UAV  530  does not have to be precisely aligned with the channel  515 . 
     For example, the UAV  530  may travel along a heading substantially parallel to the channel  515 , but two feet left or right of the channel  515  itself. The UAV  530  does not need to adjust the approach or flight path because the tether guide  505 , with a maximum width of approximately four feet (in this example), will direct or steer the tether  540  to the channel  515  such that the payload coupling apparatus arrives at the target location. Moreover, the channel  515  may limit any swing of the payload coupling apparatus  550  as the UAV  530 , tether  540 , and payload coupling apparatus  550 , move across and through (respectively) the loading structure  502 . In other words, the tether guide  505  and the channel  515  may constrain the movement of the tether  550  in at least one degree of freedom (left or right of the channel  515  in this example) 
     While the channel  515  is shown in a straight line in  FIG.  5   , other shapes are considered herein. For example, the channel  515  may be curved in order to direct and guide the tether  540  such that the payload coupling apparatus  550  reaches the target location within the merchant module or loading structure  502 . Similarly, while the channel  515  is the only channel shown in  FIG.  5   , multiple channels are considered herein. For example, the channel  515  may split into one or more channels and the tether  540  may be routed into a specific channel based on a specific target location that the payload coupling apparatus  550  has been assigned to arrive within to pick up (or drop off) a payload. Additionally, while the one UAV  530  is depicted in  FIG.  5   , two or more UAVs may travel across the landing platform  510  and the loading structure  502  at one time. For example, UAVs may line up and each corresponding payload coupling apparatus may enter through the UAV approach opening  507  one at a time, but two or three payload coupling apparatuses (corresponding to two or three UAVs) may be within the loading structure  502  so multiple users may load a payload to each of the payload coupling apparatuses simultaneously or approximately at the same time. 
     While  FIG.  5    was described generally as picking up the payload  560  from a merchant module, it is also considered herein that the loading structure  502  could also be a residence or common location in a community that is designated as a location where deliveries from a UAV delivery service may be dropped off. Other similar design considerations are contemplated. 
     Continuing with the Figures,  FIGS.  6 A- 6 D  depict a payload loading system  600 . The payload loading system  600  includes a loading structure  602  and a UAV  630 . The payload loading structure  600  may include components similar to the payload loading structure  500  provided in  FIG.  5    and/or the payload loading structure  400  provided in  FIGS.  4 A- 4 C , even if those components are not explicitly labeled. Moreover, features of the payload loading structure  600  may be similar in form and function to components of the payload loading structure  500  and/or the payload loading structure  400 . For example, the loading structure  602  and the UAV  630  may be similar to the loading structure  502  and the UAV  530  of  FIG.  5   . 
     The UAV  630  is shown approaching the landing structure  602 . The UAV  630  includes a tether  640  and a payload coupling apparatus  650 . The landing structure  602  includes a landing platform  610  (dividing into a plurality of landing platform portions  610 A- 610 E), and a tether guide. The tether guide includes a plurality of lower tether guide edges  620 A- 620 D. The plurality of lower tether guide edges  620 A- 620 D of the tether guide define a plurality of tether paths  622 A- 622 C. Each of the plurality of lower tether guide edges  620 A- 620 D may be constructed from elements of the loading structure  602 , such as partitions, stanchions, or pipes, among other possibilities. The tether guide further includes a plurality of upper tether guide edges  610 AA,  610 BA,  610 BB,  610 CB,  610 CC,  610 DC,  610 DD, and  610 ED. The plurality of upper tether guide edges  610 AA,  610 BA,  610 BB,  610 CB,  610 CC,  610 DC,  610 DD, and  610 ED are edges of the landing platform  610  that includes the plurality of landing platform portions  610 A- 610 E. Furthermore, a plurality of channels  615 A- 615 D are between pairs of the plurality of platform portions  610 A- 610 E. As such, the landing platform  610  includes at least one channel, where each channel is between two of the landing platform portions  610 A- 610 E. 
     The lower tether guide edges  620 A- 620 D, the upper tether edges, and/or the channels  615 A- 615 D may be constructed from low friction material such that the tether  640  more easily slides or is guided by the respective features of the tether guide when the tether  640  is guided or positioned within the loading structure  602 . Moreover, the various features of the loading structure  602  and tether guide may include force, touch, or other sensing means that allow the UAV  630  to determine a position of the tether  640  within the loading structure  602 . 
     As depicted in  FIGS.  6 A- 6 D , each of the channels  615 A- 615 D has a pair of upper tether guide edges that direct or funnel the tether  640  into the respective channel. For example, the channel  615 A is between the platform portion  610 A and the platform portion  610 B. Further, the tether guide edge  610 AA (of platform portion  610 A) and the tether guide edge  610 BA (of platform portion  610 B) are angled such that the tether  640  is directed to channel  615 A. Similarly, the channel  615 B is between the platform portion  610 B and the platform portion  610 C. Further, the tether guide edge  610 BB (of platform portion  610 B) and the tether guide edge  610 CB (of platform portion  610 C) are angled such that the tether  640  is directed to channel  615 B. The arrangement of the similar features of the upper tether guide (edges of and channels between the plurality of landing platform portions), are similar. 
     When the tether  640  is guided by the upper tether guide, the tether  640  will come into contact with at least one of the plurality of upper tether guide edges and contact and pass through at least a portion of one of the channels such that the payload coupling apparatus arrives at a target location  690 . The respective tether guide edges and channel may contact and interact with an upper portion of the tether  640  that is closer to a proximate end of the tether  640  where the tether  640  is coupled to the UAV  630 . As shown in  FIGS.  6 A- 6 D , none of the channels  615 A- 615 D are in plumb with (or vertically aligned with) any portion of the target location  690 . Further, the upper tether guide (i.e. the tether guide edges and the channels) directs the tether  640  in a direction that has substantially the same heading as the heading or flight path of the UAV  630  while the tether  640  is passing through the channel. 
     The lower tether guide edges  620 A- 620 D are located at a position below the plurality of platform portions  610 A- 610 E. Additionally, the target location  690  is located just below a portion of the lower tether guide edges  620 A- 620 D. The plurality of lower tether guide edges  620 A- 620 D direct the tether  640  as the UAV  630  travels across one or more of the platform portions  610 A- 610 E such that the payload coupling apparatus  650  arrives at the target location  690 . As described above, the plurality of tether guide edges  620 A- 620 D define the plurality of tether paths  622 A- 622 C. The tether  640 , and more particularly a lower portion of the tether  640  closer to a distal end of the tether  640  that is coupled to the payload coupling apparatus, comes into contact with and interacts with the plurality of tether guide edges  620 A- 620 D. As such, the plurality of the lower tether guide edges  620 A- 620 D direct the tether  640  along one of the plurality of tether paths  622 A- 622 C such that the payload coupling apparatus  650  arrives at the target location  690  as the UAV travels across at least a portion of one or more platform portions  610 A- 610 E. In other words, at least a portion of the tether  640  follows one of the tether paths  622 A- 622 C as the UAV  630  travels across the landing platform. 
     Each of the tether paths  622 A,  622 B, and  622 C, lead through a portion of the target location  690 , and as such, each of the tether paths  622 A,  622 B, and  622 C (defined by the tether guide edges  620 A- 620 D) direct at least a portion of the tether  640  such that the payload coupling apparatus  650  arrives at the target location  690 . Additionally, the plurality of tether guide edges  620 A- 620 D may be shaped and angled so that the payload coupling apparatus  650  reaches the target location  690 . The lower portion of the tether  640  travels along one of the tether paths  622 A- 622 C in arriving at the target location  690 . Within examples, and as shown in  FIGS.  6 A- 6 D , at least a portion of each of the tether paths  622 A,  622 B, and  622 C defined by the plurality of tether guide edges  620 A- 620 D may put the tether  640  on a heading or direction that is different than a heading or direction that the UAV  630  is traveling. Further then, a path that the UAV  630  travels (e.g., a flight path), may be in a different heading than at least a portion of the tether  640  following one of the tether paths  622 A- 622 C. 
     Within further embodiments, aspects of the loading structure  602  may be actuated such that the payload coupling apparatus  650  is guided to the target location  690 . For example, a specific target location (such as the target location  690 ) may be chosen based on contents of a payload to be dropped off or picked up. One or more the lower tether guide edges  620 A- 620 D may be actuated so that a given tether path is shifted to lead the tether  640  to a predetermined target location. For example, once a tether has entered the loading structure  602 , the payload loading system  600  may determine a next payload to be picked up, and then shift the lower tether guide edges  620 A- 620 D to guide the tether  640  such that the payload coupling apparatus  650  reaches the target location  690 . In other examples, other features such as a channel of the loading structure  602  may also be movable. Actuated mechanical features of the loading structure  602  may provide more flexibility to get the payload coupling apparatus  650  to a specific, predetermined target location. 
     The embodiment of  FIGS.  6 A- 6 D  may be further understood by going through each of the  FIGS.  6 A- 6 D  as the UAV  630  approaches the landing structure  602 , travels across the platform  610 , and providing how the payload coupling apparatus  650  arrives at the target location  690 . 
     Beginning with  FIG.  6 A , the UAV  630  is approaching the landing structure  602  with the tether  640  extended a distance that is greater than a vertical distance between the platform portions  610 A- 610 E and the tether guide edges  620 A- 620 D. Additionally, the tether  640  must be extended a distance that the payload coupling apparatus  650  reaches the target location  690  with the UAV  630  above on or hovering over the landing platform  610 . The features described above provide that so long as the UAV  630  approaches within a width of the landing platform  610  (i.e., the outer edge of platform portion  610 A to the outer edge of platform portion  610 E), the tether  640  will be guided by the tether guide(s) and the payload coupling apparatus  650  will arrive at the target location  690 . Additionally, it is worth noting that while the tether guide edges shown are located on one side of the platform portions  610 A- 610 E, in other embodiments the platform portions  610 A- 610 E may have the same or similar shape mirrored on the other side of the platform in order to allow the UAV  630  to land from either direction. Moreover, while certain angles and shapes are shown, others are possible and contemplated herein. 
     Continuing to  FIG.  6 B , the UAV  630  has landed on the landing platform  610 , and more particularly has landing on platform portions  610 E and  610 D. As the UAV  630  made the landing, the tether  640  was directed by at least the tether guide edge  620 D and possible one or both of the tether guide edges  610 ED and/or  610 DD. As shown in  FIG.  6 B , the upper portion of tether  640 , nearer the UAV  630 , is passing through the channel  615 D, between the two platform portions  610 E and  610 D. Based on the location on the platform  610  that the UAV  630  landed, the lower portion of the tether  640 , nearer the payload coupling apparatus  650 , and the payload coupling apparatus  650  itself, is following the tether path  622 C defined between the tether guide edge  620 D and  620 C. If the UAV  630  had landed in a position such that the upper portion of the tether  640  ended up going through channel  615 B or  615 C, the lower portion of the tether  640  and the payload coupling apparatus  650  would follow tether path  622 B. Further, if the UAV  630  had landed in a position such that the upper portion of the tether  640  ended up going through channel  615 A, the lower portion of the tether  640  and the payload coupling apparatus  650  would follow tether path  622 A. As shown in  FIG.  6 B , at this point while the UAV  630  has one heading along a flight path (e.g., directly right to left on the page), the payload coupling apparatus  650  and a portion of the tether  640  follow the tether path  622 C at a different heading. The tether path  622 C directs the tether  640  such that the payload coupling apparatus  650  will arrive at the target location  690 . 
       FIGS.  6 C and  6 D  are different views depicting the UAV  630  in the same position. The UAV  630  has traveled across the landing platform  610  and as the UAV  630  has traveled, the payload coupling apparatus  650  has arrived at the target location  690 . The tether  640  followed the tether path  622 C as the tether  640  was directed and guided by the lower tether guide edge  620 D of the tether guide. As shown in  FIG.  6 D , a top view of the payload loading system  600 , the UAV  630  is off-plumb from the payload coupling apparatus  650  as well as the target location  690 . As such, without the use of the lower edges of the tether guide, the payload coupling apparatus  650  would be located directly below the UAV  630  and not within the target location  690 , in some examples. As such,  FIGS.  6 A- 6 D  provide various elements of an example as to how a tether guide may direct a tether such that the payload coupling apparatus arrives at the target location, even if the UAV is not located immediately above the target location. The payload loading system provides the features necessary to locate the payload coupling apparatus in the target location. 
       FIG.  7    depicts yet another embodiment of a payload loading system  700 . The payload loading system  700  includes a plurality of UAVs  730  and a loading structure  702 . The loading structure  702  includes a landing platform  710  and a plurality of landing pads  713 . The payload loading structure  700  may include components similar to the payload loading structure  600  provided in  FIGS.  6 A- 6 D , the payload loading structure  500  of  FIG.  5   , and/or the payload loading structure  400  provided in  FIGS.  4 A- 4 C , even if those components are not explicitly labeled. Moreover, features of the payload loading structure  700  may be similar in form and function to components of the payload loading structure  600 , the payload loading structure  500 , and/or the payload loading structure  400 . For example, the loading structure  702  and the UAV  730  may be similar to the loading structure  602  and the UAV  630  of  FIGS.  6 A- 6 D . 
     The UAVs  730  each include a tether  740  and a payload coupling apparatus  750 . The UAVs  730  are located on one of the plurality of landing pads  713 . While in contact with the landing pad, the UAVs  730  may charge a battery, among other tasks described herein. A plurality of tether guides  705 , one corresponding to each of the landing pads  713 , are configured such that when one of the UAVs  730  is on the landing pad  713 , the tether guide  705  maintains an alignment of the tether  740  such that the payload coupling apparatus  750  is within a target location. 
     Moreover, when one of the UAVs  730  lands on one of the landing pads  713 , the edges and angle of the tether guide  705  are such that the tether  740  is directed or funneled to an apex  706  of the tether guide  705 . The apex  706  is where a first edge  709 A of the tether guide  705  and a second edge  709 B of the tether guide  705  meet. The first edge  709 A and the second edge  709 B may be constructed from a low friction material such that the tether  740  is guided and more easily positioned by the tether guide  705 . Positioning of the tether  740  in the apex  706  of the tether guide  705  may limit any movement of the tether  740  as well as the payload coupling apparatus  750 . In other examples, the apex  706  may include a roller configured to rotate as the tether  740  is reeled-in or payed-out during a loading or unloading process. Moreover, the roller (or another sensing feature in other embodiments) of the apex  706  may enable a winch system of the UAV  730  to sense or determine that a payload has been loaded to or unloaded from the payload coupling apparatus  750 . Furthermore, no matter the heading or orientation of the UAV  730 , so long as the UAV  730  lands on one the landing pads  713 , the tether  740  will hang from the apex  706  of the tether guide  705 . 
     The landing platform  710  may be coupled to a side or wall merchant module. For example, the landing platform  710  depicted in  FIG.  7    may be coupled to a wall of a warehouse such that the landing platform  710  is cantilevered off the wall. One advantage of the landing platform  710  is that it may be easily installed on existing structures with minimal impact to the existing structure. Further, while three landing pads  713  with three UAVs  730  are shown, more or less of both are contemplated herein. 
       FIGS.  8 A- 8 C  illustrate a payload loading system  800 . The payload loading system  800  includes a plurality of UAVs  830  and a loading structure  802 . The loading structure  802  includes a landing platform  810  and a plurality of landing pads  813 . The payload loading structure  800  may include components similar to the payload loading structure  700  provided in  FIG.  7   , the payload loading structure  600  provided in  FIGS.  6 A- 6 D , the payload loading structure  500  of  FIG.  5   , and/or the payload loading structure  400  provided in  FIGS.  4 A- 4 C , even if those components are not explicitly labeled. Moreover, features of the payload loading structure  800  may be similar in form and function to components of the payload loading structure  600 , the payload loading structure  600 , the payload loading structure  500 , and/or the payload loading structure  400 . For example, the loading structure  802  and the UAVs  830  may be similar to the loading structure  702  and the UAVs  730  of  FIG.  7   . 
       FIG.  8 A  depicts the loading platform  810  and a tether guide  805  of the loading structure  802 . The tether guide  805  is coupled to the loading platform  810 . Moreover, the tether guide  805  is conical. The tether guide  805  may have an edge  809 . The tether guide  805  may be coupled to the loading platform  810  at the edge  809 . The edge  809  may be circular in shape. 
     The conical tether guide  805  extends down from the landing platform  810  towards a target location. The tether guide  805  includes a first tapered portion  825 , a middle portion  827 , and a second tapered portion  829 . The first tapered portion  825 , the middle portion  827 , and the second tapered portion  829  are concentric. The first tapered portion  825  is coupled to the landing platform  810  at a proximate end of the first tapered portion  825 . Further, a diameter of the first tapered portion  825  at the proximate end of the first tapered portion  825  is greater than a diameter of a diameter of the first tapered portion  825  at a distal end of the first tapered portion  825 . A proximate end of the second tapered portion  829  may be coupled to the distal end of the first tapered portion  825 . In other examples, such as shown in  FIGS.  8 A- 8 C , the distal end of the first tapered portion  825  may be coupled to the middle portion  827 . Also, the proximate end of the second tapered portion  829  may be coupled to the middle portion  827 . The middle portion  827  is cylindrical and may extend vertically between the first tapered portion  825  and the second tapered portion  829 . The middle portion  827  may have a diameter equal to the diameter of the distal end of the first tapered portion  825 . 
     Additionally, a diameter of the proximate end of the second tapered portion  829  may be the same as the diameter of the distal end of the first tapered portion  825 . A diameter of a distal end of the second tapered portion  829  is greater than the diameter of the proximate end of the second tapered portion  829 . 
     As depicted in  FIG.  8 B , the loading structure  802  may also include a merchant module  803 . The merchant module  803  may include a food truck, a building, a warehouse, a retail outlet, among other possibilities. The landing platform  810  and the tether guide  805  may be coupled to and/or installed in the merchant module  803 . The UAVs  830  may land on the landing pads  813  on the landing platform  810  in a manner such that a payload coupling apparatus  850  coupled to a tether  840  of one of the UAVs  830  is deposited within the conical tether guide  805 . The tether  840  may extend from the UAV  830  through the tether guide  805  to a target location  890 . 
     As provided in  FIG.  8 C , the payload coupling apparatus  850  may be directed or guided to the target location  890  within the merchant module  803  as the UAV  830  approaches the landing platform  810 . The tapered design of the tether guide  805 , and in particular the outward taper of the second tapered portion  829  described above allows the payload coupling apparatus  850  and a payload coupled thereto to enter and exit the merchant module  803  and the tether guide  805  without getting caught on an edge of the tether guide  805 . Within examples, the tether  840  may hang from the distal end of the first tapered portion  825 . In other words, the tether  840  may be in contact with the conical tether guide  805  at the distal end of the first tapered portion  825  when the payload is loaded to, or unloaded from the payload coupling apparatus  850 . In some embodiments, the distal end of the first tapered portion  825  and the proximate end of the second tapered portion  829  may be the same. 
     The payload loading system  800  may allow for the grouping of multiple payload coupling apparatuses in one location at a single time, such as the target location  890 . This configuration may be preferable for some merchants or other users based on the need and available space for integration of a payload loading system to utilize UAV delivery services. 
     Continuing,  FIGS.  9 A and  9 B  depict a payload loading system  900 . The payload loading system  900  may be similar to the payload loading system  400  of  FIGS.  4 A- 4 C . Further, a loading structure  902 , a UAV approach opening  907 , a channel  915 , a UAV  930 , and a payload  960  may all be similar to components disclosed within the payload loading system  400 . Further, a landing platform  910  may be similar in some aspects to the landing platform  410 . 
     The landing platform  910  of  FIGS.  9 A and  9 B  further includes a first hinged door  911 A, a first spring  912 A, a second hinged door  911 B, and a second spring  912 B. The first hinged door  911 A and the second hinged door  911 B may open when the UAV  930  departs from the loading structure  902  with the payload  960 . In some examples, the UAV  930  may fly forward with a tether extended such that the tether passes through the rest of the channel  915 . Once in flight and clear of the loading structure  902 , the UAV  930  may retract the tether using a winch system. However, as depicted in  FIGS.  9 A and  9 B , in another embodiment, the UAV  930  may begin to hover above the landing platform  910  and retract the tether such that the tether pulls the payload  960  through the hinged doors  911 A- 911 B. 
     In some examples, the springs  912 A- 912 B may be coupled between each of the hinged doors  911 A- 911 B, respectively. The springs  912 A- 912 B may be in a compressed state when the hinged doors  911 A- 911 B are down such that the hinged doors  911 A- 911 B exert less force against the payload  960  as the payload  960  is pulled through than the hinged doors  911 A- 911 B otherwise would. In some embodiments, the UAV  930  may hover until the payload  960  is retracted fully up to the UAV  930 , while in other embodiments the UAV  930  may begin to fly forward as the tether is retracted and/or the payload  960  is still being pulled through the hinged doors  911 A- 911 B. Other modes of take-off and departure from the loading structure are contemplated herein. 
       FIG.  10    depicts a payload loading system  1000  within a warehouse  1070 . The payload system  1000  may include components and function similarly to the other payload loading systems disclosed herein. Moreover, the payload loading system  1000  may be considered one example implementation of a payload loading system disclosed herein within a different merchant module (i.e., the warehouse  1070 ). The payload loading system  1000  includes a loading structure  1002  that further includes tether guides  1005 , a landing platform  1010 , and landing pads  1013 . The warehouse  1070  may include one or more openings  1007  for UAVs to enter and exit the warehouse  1070  in order to deliver and pick up various payloads. In some examples, the warehouse  1070  may be a distribution center for a UAV delivery service. Moreover, the loading structure  1002  includes a plurality of docking stations  1014  for UAVs to charge, be maintained, and otherwise be prepared for use within a UAV delivery service. 
       FIG.  11    depicts a payload loading system  1100  within a warehouse  1170 . The payload system  1000  may include components and function similarly to the other payload loading systems disclosed herein. The payload loading system  1100  includes a loading structure  1102  that is coupled to a plurality of modules  1103 . Each of the modules  1103  may include one type of good to be distributed via a UAV delivery service, among other examples. UAVs may enter and exit the warehouse  1170  through one or more openings  1107 . The loading structure  1102  further includes a plurality of tether guides  1105 , a landing platform  1110 , and a plurality of landing pads  1113 . Further, the payload loading system  1100  includes a plurality of docking stations  1114  on UAV docking structures  1180  for UAVs to charge, be maintained, and otherwise be prepared for use within a UAV delivery service. 
     Additionally, a method for loading a payload to a UAV is disclosed.  FIG.  12    is a simplified block diagram illustrating a method  1200  for loading a payload to a UAV, according to an example embodiment. It should be understood that example methods, such as method  1200 , might be carried out by entities, or combinations of entities (i.e., by other computing devices, and/or combinations thereof), without departing from the scope of the invention. 
     For example, functions of the method  1200  may be fully performed by a machine, a human operator, a computing device (or components of a computing device such as one or more processors or controllers), or may be distributed across multiple components of the computing device, across multiple computing devices, and/or across a server. In some examples, the computing device may receive information from input commands initiated by an operator, sensors of the computing device, or may receive information from other computing devices that collect the information. 
     As shown by block  1202 , the method  1200  includes a UAV traveling across at least a portion of a landing platform. Within examples, the landing platform may be coupled to a loading structure. The loading structure may be part of a payload loading system and may further be part of a UAV delivery service. The loading structure and landing platform may be coupled to existing structures, or in other examples the loading structure and landing platform may be installed as new structures. The loading structure and landing platform may be located at merchant modules, food trucks, warehouses, distributions centers, residences, within communities, among other locations. 
     As shown by block  1204 , the method  1200  further includes guiding a tether such that a payload coupling apparatus arrives at a target location. The tether is guided by a tether guide that is couple to the loading structure. The payload coupling apparatus may be coupled to a tether, and the tether may be coupled to the UAV. The tether may be extended from the UAV as the tether is guided by the tether guide. 
     As shown by block  1206 , the method  1200  further includes loading a payload. The payload is loaded to the UAV by coupling the payload to the payload coupling apparatus while the payload and payload coupling apparatus are within the target location. 
     The method  1200  may further include additional aspects. For example, the method  1200  may include locating at least a portion of the tether within an opening of the loading structure as the UAV approaches the loading structure. In another example, the method  1200  may include locating the payload coupling apparatus within an opening of the loading structure as the UAV approaches the loading structure. Locating the tether and/or the payload coupling apparatus as the UAV approaches may be carried out by the UAV in flight. Locating the tether and/or the payload coupling apparatus may be completed by the UAV as a check of the UAV&#39;s alignment and orientation relative to the landing platform. Further, locating the tether and/or payload coupling apparatus may act as a check that the tether is aligned such that the tether will be funneled and guided by the tether guide. Moreover, the method  1200  may include maintaining an alignment of the tether by the UAV and tether guide as the payload is loaded to the UAV. 
     The method  1200  may further include charging a battery of the UAV when the UAV lands on the landing platform. In other examples, the UAV may charge when the UAV comes into contact with a landing pad within the landing platform. Within yet other embodiments, the method  1200  may include unloading a first payload from the payload coupling apparatus before loading a second payload. The method  12  may also include extending the tether a length by the UAV such that the payload coupling apparatus is below the tether guide as the UAV approaches and/or travels across the landing platform. 
     In other embodiments the method  1200  may include more or less blocks as well as blocks that carry out various functions described herein. Also, while the blocks are expressed in a specific order herein, other ordering of the various blocks is considered herein. 
     VI. Conclusion 
     It should be understood that arrangements described herein are for purposes of example only. As such, those skilled in the art will appreciate that other arrangements and other elements (e.g. machines, interfaces, operations, orders, and groupings of operations, etc.) can be used instead, and some elements may be omitted altogether according to the desired results. Further, many of the elements that are described are functional entities that may be implemented as discrete or distributed components or in conjunction with other components, in any suitable combination and location, or other structural elements described as independent structures may be combined. 
     While various aspects and implementations have been disclosed herein, other aspects and implementations will be apparent to those skilled in the art. The various aspects and implementations disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope being indicated by the following claims, along with the full scope of equivalents to which such claims are entitled. It is also to be understood that the terminology used herein is for the purpose of describing particular implementations only, and is not intended to be limiting.