Patent Publication Number: US-11377232-B2

Title: Combined information for object detection and avoidance

Description:
PRIORITY CLAIM 
     This application is a continuation of U.S. patent application Ser. No. 15/913,599, filed Mar. 6, 2018, and titled Combining Information for Object Detection and Avoidance, which is a continuation of U.S. Pat. No. 9,963,246, issued May 8, 2018, and titled “Combining Depth And Thermal Information For Object Detection And Avoidance,” each of which are herein incorporated by referenced in their entirety. 
    
    
     BACKGROUND 
     The use of unmanned aerial vehicles (“UAV”) having two or more propellers is increasingly common. Such vehicles include quad-copters (e.g., a UAV having four rotatable propellers), octo-copters (e.g., a UAV having eight rotatable propellers), or other vertical take-off and landing (“VTOL”) aircraft having two or more propellers. 
     One of the benefits of UAVs is that they are highly maneuverable in the vertical and horizontal direction, are relatively small, and can be navigated into confined spaces that other, larger vehicles, cannot access. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description is set forth with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number appears. 
         FIG. 1  depicts a view of an unmanned aerial vehicle configuration, according to an implementation. 
         FIG. 2  illustrates an imaging component that may be used with an unmanned aerial vehicle, according to an implementation. 
         FIG. 3  illustrates a visual image of a delivery location obtained with one or more imaging devices of the imaging component of  FIG. 2 , according to an implementation. 
         FIG. 4A  illustrates a depth map of the delivery location, according to an implementation. 
         FIG. 4B  illustrates a thermogram of the delivery location, according to an implementation. 
         FIG. 5  is a depth and thermal representation of the delivery location produced from a combination of the depth map and the thermogram, according to an implementation. 
         FIG. 6  is a flow diagram of an example descent analysis process, according to an implementation. 
         FIG. 7  is a flow diagram of an example descent process, according to an implementation. 
         FIG. 8  is a block diagram of an illustrative implementation of an aerial vehicle control system that may be used with various implementations. 
     
    
    
     While implementations are described herein by way of example, those skilled in the art will recognize that the implementations are not limited to the examples or drawings described. It should be understood that the drawings and detailed description thereto are not intended to limit implementations to the particular form disclosed but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean “including, but not limited to.” Additionally, as used herein, the term “coupled” may refer to two or more components connected together, whether that connection is permanent (e.g., welded) or temporary (e.g., bolted), direct or indirect (i.e., through an intermediary), mechanical, chemical, optical, or electrical. Furthermore, as used herein, “horizontal” or “transit” flight refers to flight traveling in a direction substantially parallel to the ground (i.e., sea level), and that “vertical” flight refers to flight traveling substantially radially outward from the earth&#39;s center. It should be understood by those having ordinary skill that trajectories may include components of both “horizontal” or “transit” and “vertical” flight vectors. 
     DETAILED DESCRIPTION 
     This disclosure describes an imaging component for use by an unmanned aerial vehicle (“UAV”) for object detection. As described, the imaging component includes one or more cameras that are configured to obtain images of a scene using visible light that are converted into a depth map (e.g., stereo image) and one or more other cameras that are configured to form images of the scene using infrared radiation (“IR”). For example, the imaging component may include a first camera and a second camera that are separated by a known baseline distance such that a field of view of the first camera overlaps with at least a portion of the field of view of the second camera. The first camera and the second camera are configured to form images using visible light. The imaging component may likewise include a third camera that is approximately equidistant between the first camera and the second camera. The third camera is configured to form a third image, or thermogram, of the scene using infrared radiation. 
     Each of the cameras may be controlled by and send the formed images to a single processing component. The processing component processes the two visual images to generate a three-dimensional (“3D”) representation, such as a stereo image, that includes a depth map in which each pixel of the 3D representation corresponds to a horizontal dimension, a vertical dimension, and a depth dimension. In addition, the processing component combines the 3D representation with the thermogram to produce combined information that provides a 3D and thermal information representative of the scene. Each pixel of the combined information includes at least a horizontal dimension, a vertical dimension, a depth dimension, and a thermal dimension. The thermal dimension may be represented by a visible color (e.g., red, green, blue combination), different colors corresponding to different thermal ranges, and/or other value. 
     The UAV control system may utilize the combined information to aid in object detection and avoidance. For example, the UAV may use the depth information to detect objects protruding above a surface of a delivery location and use the thermal information to determine whether the object is a warm-blooded or non-warm-blooded object. If the object is a warm-blooded object, the delivery of an item may be aborted, a descent of the UAV terminated, and/or the delivery position altered to avoid the warm-blooded object. 
     In some implementations, even though the protruding object has a thermal signature, it may be determined that the object is non-warm-blooded (e.g., a grill or lamp). Upon determining that the object is non-warm-blooded, the signature of the object may be retained and used during further UAV navigation to detect and avoid warm-blooded objects. 
     By combining both depth and thermal information for objects within a delivery area, safety to humans and/or other animals is improved and false detection of warm-blooded objects is reduced. For example, if a warm-blooded object, such as a dog, is laying near a delivery location, using only depth information the UAV may only be able to determine that the object (dog) protrudes from the surface but may not determine that the object is warm-blooded because the object is motionless. By combining thermal information with the depth information, the UAV can accurately determine that the object both protrudes from the surface and has a thermal signature in a range that corresponds with a warm-blooded object. 
     In a similar manner if a non-warm-blooded object, such as a chair, is near a delivery location, using only depth information, the UAV may only be able to determine that the objects protrude from the surface and may inaccurately determine that the objects are warm-blooded objects, thereby altering or aborting a delivery. By combining thermal information with the depth information, the UAV can accurately determine that the chair does not have a thermal signature in a range that corresponds with a warm-blooded object, and therefore may continue its descent. In some instances, a non-warm-blooded object may include a thermal signature that potentially corresponds with a warm-blooded object, because the non-warm-blooded object expels heat that is detected by the IR camera. For example, a lamp or BBQ may expel heat that is detected by the thermal camera. In such instances, the objects are detected as protruding from the surface and including a thermal signature that potentially corresponds with a warm-blooded object. In such an instance, the signature of the objects (e.g., depth information, thermal information) may be determined over a period of time and used to determine that the object is a non-warm-blooded object. 
       FIG. 1  illustrates a view of a UAV  100 , according to an implementation. As illustrated, the UAV  100  includes a perimeter frame  104  that includes a front wing  120 , a lower rear wing  124 , an upper rear wing  122 , and two horizontal side rails  130 - 1 ,  130 - 2 . The horizontal side rails  130  are coupled to opposing ends of the front wing  120  and opposing ends of the upper rear wing  122  and lower rear wing  124 . In some implementations, the coupling may be with a corner junction, such as the front left corner junction  131 - 1 , the front right corner junction  131 - 2 , the rear left corner junction  131 - 3 , the rear right corner junction  131 - 4 . In such an example, the corner junctions are also part of the perimeter frame  104 . 
     The components of the perimeter frame  104 , such as the front wing  120 , lower rear wing  124 , upper rear wing  122 , side rails  130 - 1 ,  130 - 2 , and corner junctions  131  may be formed of any one or more suitable materials, such as graphite, carbon fiber, aluminum, titanium, etc., or any combination thereof. In the illustrated example, the components of the perimeter frame  104  of the UAV  100  are each formed of carbon fiber and joined at the corners using corner junctions  131 . The components of the perimeter frame  104  may be coupled using a variety of techniques. For example, if the components of the perimeter frame  104  are carbon fiber, they may be fitted together and joined using secondary bonding, a technique known to those of skill in the art. In other implementations, the components of the perimeter frame  104  may be affixed with one or more attachment mechanisms, such as screws, rivets, latches, quarter-turn fasteners, etc., or otherwise secured together in a permanent or removable manner. 
     The front wing  120 , lower rear wing  124 , and upper rear wing  122  are positioned in a tri-wing configuration and each wing provides lift to the UAV  100  when the UAV is moving in a direction that includes a horizontal component, also referred to herein as transit flight. For example, the wings may each have an airfoil shape that causes lift due to the airflow passing over the wings during transit flight. 
     Opposing ends of the front wing  120  may be coupled to a corner junction  131 , such as the front left corner junction  131 - 1  and front right corner junction  131 - 2 . In some implementations, the front wing may include one or more flaps  127  or ailerons, that may be used to adjust the pitch, yaw, and/or roll of the UAV  100  alone or in combination with the lifting motors  106 , lifting propellers  102 , thrusting motors  110 , thrusting propellers  112 , and/or other flaps on the rear wings, discussed below. In some implementations, the flaps  127  may also be used as a protective shroud to further hinder access to the lifting propellers  102  by objects external to the UAV  100 . For example, when the UAV  100  is moving in a vertical direction or hovering, the flaps  127  may be extended to increase the height of the protective barrier around a portion of the lifting propellers  102 . 
     In some implementations, the front wing  120  may include two or more pairs of flaps  127 , as illustrated in  FIG. 1 . In other implementations, for example if there is no front thrusting motor  110 - 1 , the front wing  120  may only include a single flap  127  that extends substantially the length of the front wing  120 . If the front wing  120  does not include flaps  127 , the lifting motors  106  and lifting propellers  102 , thrusting motors  110 , thrusting propellers  112  and/or flaps of the rear wings may be utilized to control the pitch, yaw, and/or roll of the UAV  100  during flight. 
     Opposing ends of the lower rear wing  124  may be coupled to a corner junction  131 , such as the rear left corner junction  131 - 3  and rear right corner junction  131 - 4 . In some implementations, the lower rear wing may include one or more flaps  123  or ailerons, that may be used to adjust the pitch, yaw and/or roll of the UAV  100  alone or in combination with the lifting motors  106 , lifting propellers  102 , thrusting motors  110 , thrusting propellers  112 , and/or the flaps  127  of the front wing. In some implementations, the flaps  123  may also be used as a protective shroud to further hinder access to the lifting propellers  102  by objects external to the UAV  100 . For example, when the UAV  100  is moving in a vertical direction or hovering, the flaps  123  may be extended, similar to the extending of the front flaps  127  of the front wing  120 . 
     In some implementations, the rear wing  124  may include two or more flaps  123 , as illustrated in  FIG. 1  or two or more pairs of flaps. In other implementations, for example if there is no rear thrusting motor  110 - 2  mounted to the lower rear wing, the rear wing  124  may only include a single flap  123  that extends substantially the length of the lower rear wing  124 . In other implementations, if the lower rear wing includes two thrusting motors, the lower rear wing may be configured to include three flaps  123 , one on either end of the lower rear wing  124 , and one between the two thrusting motors mounted to the lower rear wing  124 . 
     Opposing ends of the upper rear wing  122  may be coupled to a corner junction  131 , such as the rear left corner junction  131 - 3  and rear right corner junction  131 - 4 . In some implementations, like the lower rear wing, the upper rear wing  122  may include one or more flaps or ailerons, that may be used to adjust the pitch, yaw and/or roll of the UAV  100  alone or in combination with the lifting motors  106 , lifting propellers  102 , thrusting motors  110 , thrusting propellers  112 , and/or other flaps of other wings. In some implementations, the flaps may also be used as a protective shroud to further hinder access to the lifting propellers  102  by objects external to the UAV  100 . For example, when the UAV  100  is moving in a vertical direction or hovering, the flaps may be extended, similar to the extending of the front flaps  127  of the front wing  120  or the flaps  123  of the lower rear wing. 
     The front wing  120 , lower rear wing  124 , and upper rear wing  122  may be positioned and sized proportionally to provide stability to the UAV while the UAV  100  is moving in a direction that includes a horizontal component. For example, the lower rear wing  124  and the upper rear wing  122  are stacked vertically such that the vertical lift vectors generated by each of the lower rear wing  124  and upper rear wing  122  are close together, which may be destabilizing during horizontal flight. In comparison, the front wing  120  is separated from the rear wings longitudinally such that the vertical lift vector generated by the front wing  120  acts together with the vertical lift vectors of the lower rear wing  124  and the upper rear wing  122 , providing efficiency, stabilization and control. 
     In some implementations, to further increase the stability and control of the UAV  100 , one or more winglets  121 , or stabilizer arms, may also be coupled to and included as part of the perimeter frame  104 . In the example illustrated with respect to  FIG. 1 , there are two front winglets  121 - 1  and  121 - 2  mounted to the underneath side of the front left corner junction  131 - 1  and the front right corner junction  131 - 2 , respectively. The winglets  121  extend in a downward direction approximately perpendicular to the front wing  120  and side rails  130 . Likewise, the two rear corner junctions  131 - 3 ,  131 - 4  are also formed and operate as winglets providing additional stability and control to the UAV  100  when the UAV  100  is moving in a direction that includes a horizontal component, such as transit flight. 
     The winglets  121  and the rear corner junctions  131  may have dimensions that are proportional to the length, width, and height of the UAV  100  and may be positioned based on the approximate center of gravity of the UAV  100  to provide stability and control to the UAV  100  during horizontal flight. For example, in one implementation, the UAV  100  may be approximately 64.75 inches long from the front of the UAV  100  to the rear of the UAV  100  and approximately 60.00 inches wide. In such a configuration, the front wing  120  has dimensions of approximately 60.00 inches by approximately 7.87 inches. The lower rear wing  124  has dimensions of approximately 60.00 inches by approximately 9.14 inches. The upper rear wing  122  has dimensions of approximately 60.00 inches by approximately 5.47 inches. The vertical separation between the lower rear wing and the upper rear wing is approximately 21.65 inches. The winglets  121  are approximately 6.40 inches wide at the corner junction with the perimeter frame of the UAV, approximately 5.91 inches wide at the opposing end of the winglet and approximately 23.62 inches long. The rear corner junctions  131 - 3 ,  131 - 4  are approximately 9.14 inches wide at the end that couples with the lower rear wing  124 , approximately 8.04 inches wide at the opposing end, and approximately 21.65 inches long. The overall weight of the UAV  100  is approximately 50.00 pounds. 
     Coupled to the interior of the perimeter frame  104  is a central frame  107 . The central frame  107  includes a hub  108  and motor arms  105  that extend from the hub  108  and couple to the interior of the perimeter frame  104 . In this example, there is a single hub  108  and four motor arms  105 - 1 ,  105 - 2 ,  105 - 3 , and  105 - 4 . Each of the motor arms  105  extend from approximately a corner of the hub  108  and couple or terminate into a respective interior corner of the perimeter frame. In some implementations, each motor arm  105  may couple into a corner junction  131  of the perimeter frame  104 . Like the perimeter frame  104 , the central frame  107  may be formed of any suitable material, such as graphite, carbon fiber, aluminum, titanium, etc., or any combination thereof. In this example, the central frame  107  is formed of carbon fiber and joined at the corners of the perimeter frame  104  at the corner junctions  131 . Joining of the central frame  107  to the perimeter frame  104  may be done using any one or more of the techniques discussed above for joining the components of the perimeter frame  104 . 
     Lifting motors  106  are coupled at approximately a center of each motor arm  105  so that the lifting motor  106  and corresponding lifting propeller  102  are within the substantially rectangular shape of the perimeter frame  104 . In one implementation, the lifting motors  106  are mounted to an underneath or bottom side of each motor arm  105  in a downward direction so that the propeller shaft of the lifting motor that mounts to the lifting propeller  102  is facing downward. In other implementations, as illustrated in  FIG. 1 , the lifting motors  106  may be mounted to a top of the motor arms  105  in an upward direction so that the propeller shaft of the lifting motor that mounts to the lifting propeller  102  is facing upward. In this example, there are four lifting motors  106 - 1 ,  106 - 2 ,  106 - 3 ,  106 - 4 , each mounted to an upper side of a respective motor arm  105 - 1 ,  105 - 2 ,  105 - 3 , and  105 - 4 . 
     In some implementations, multiple lifting motors may be coupled to each motor arm  105 . For example, while  FIG. 1  illustrates a quad-copter configuration with each lifting motor mounted to a top of each motor arm, a similar configuration may be utilized for an octo-copter. For example, in addition to mounting a motor  106  to an upper side of each motor arm  105 , another lifting motor may also be mounted to an underneath side of each motor arm  105  and oriented in a downward direction. In another implementation, the central frame may have a different configuration, such as additional motor arms. For example, eight motor arms may extend in different directions and a lifting motor may be mounted to each motor arm. 
     The lifting motors may be any form of motor capable of generating enough rotational speed with the lifting propellers  102  to lift the UAV  100  and any engaged payload, thereby enabling aerial transport of the payload. 
     Mounted to each lifting motor  106  is a lifting propeller  102 - 1 ,  102 - 2 ,  102 - 3 , and  102 - 4 . The lifting propellers  102  may be any form of propeller (e.g., graphite, carbon fiber) and of a size sufficient to lift the UAV  100  and any payload engaged by the UAV  100  so that the UAV  100  can navigate through the air, for example, to deliver a payload to a delivery location. For example, the lifting propellers  102  may each be carbon fiber propellers having a dimension or diameter of twenty-four inches. 
     While the illustration of  FIG. 1  shows the lifting propellers  102  all of a same size, in some implementations, one or more of the lifting propellers  102  may be different sizes and/or dimensions. Likewise, while this example includes four lifting propellers  102 - 1 ,  102 - 2 ,  102 - 3 ,  102 - 4 , in other implementations, more or fewer propellers may be utilized as lifting propellers  102 . Likewise, in some implementations, the lifting propellers  102  may be positioned at different locations on the UAV  100 . In addition, alternative methods of propulsion may be utilized as either lifting motors or thrusting “motors” in implementations described herein. For example, fans, jets, turbojets, turbo fans, jet engines, internal combustion engines, and the like may be used (either with propellers or other devices) to provide lift for the UAV. 
     In addition to the lifting motors  106  and lifting propellers  102 , the UAV  100  may also include one or more thrusting motors  110  and corresponding thrusting propellers  112 . The thrusting motors and thrusting propellers may be the same or different than the lifting motors  106  and lifting propellers  102 . For example, in some implementations, the thrusting propellers may be formed of carbon fiber and be approximately eighteen inches long. In other implementations, the thrusting motors may utilize other forms of propulsion to propel the UAV. For example, fans, jets, turbojets, turbo fans, jet engines, internal combustion engines, and the like may be used (either with propellers or with other devices) as the thrusting motors. 
     The thrusting motors and thrusting propellers may be oriented at approximately ninety degrees with respect to the perimeter frame  104  and central frame  107  of the UAV  100  and utilized to increase the efficiency of flight that includes a horizontal component. For example, during transit flight, flight that includes a horizontal component, the thrusting motors may be engaged to provide a horizontal thrust force via the thrusting propellers to propel the UAV  100  horizontally. As a result, the speed and power utilized by the lifting motors  106  may be reduced. Alternatively, in selected implementations, the thrusting motors may be oriented at an angle greater or less than ninety degrees with respect to the perimeter frame  104  and the central frame  107  to provide a combination of thrust and lift. 
     In the example illustrated in  FIG. 1 , the UAV  100  includes two thrusting motors  110 - 1 ,  110 - 2  and corresponding thrusting propellers  112 - 1 ,  112 - 2 . Specifically, in the illustrated example, there is a front thrusting motor  110 - 1  coupled to and positioned near an approximate mid-point of the front wing  120 . The front thrusting motor  110 - 1  is oriented such that the corresponding thrusting propeller  112 - 1  is positioned inside the perimeter frame  104 . The second thrusting motor is coupled to and positioned near an approximate mid-point of the lower rear wing  124 . The rear thrusting motor  110 - 2  is oriented such that the corresponding thrusting propeller  112 - 2  is positioned inside the perimeter frame  104 . 
     While the example illustrated in  FIG. 1  illustrates the UAV with two thrusting motors  110  and corresponding thrusting propellers  112 , in other implementations, there may be fewer or additional thrusting motors and corresponding thrusting propellers. For example, in some implementations, the UAV  100  may only include a single rear thrusting motor  110  and corresponding thrusting propeller  112 . In another implementation, there may be two thrusting motors and corresponding thrusting propellers mounted to the lower rear wing  124 . In such a configuration, the front thrusting motor  110 - 1  may be included or omitted from the UAV  100 . Likewise, while the example illustrated in  FIG. 1  shows the thrusting motors oriented to position the thrusting propellers inside the perimeter frame  104 , in other implementations, one or more of the thrusting motors  110  may be oriented such that the corresponding thrusting propeller  112  is oriented outside of the protective frame  104 . 
     In the illustrated example, the UAV also includes an imaging component  150  that is coupled to the frame  104  of the UAV with a gimbal  152 . The imaging component  150  is discussed in further detail below with respect to  FIG. 2 . The gimbal  152  may be a one, two, or three axis gimbal that is used to alter an orientation and/or position of the imaging component  150 . Imaging components  150 , in which the orientation, angle, or other position of the imaging component are adjustable with respect to the UAV  100 , are referred to herein as adjustable imaging components. In other implementations, the imaging component may be directly coupled to and/or incorporated into the frame  104  of the UAV  100 . Such imaging components  150 , in which the orientation, angle, or other position of the imaging component is not adjustable with respect to the UAV  100  is referred to herein as a fixed imaging component. Regardless, for purposes of discussion, fixed imaging components and adjustable imaging component are referred to herein collectively as imaging components, unless specifically referenced otherwise. 
     While the example illustrated in  FIG. 1  presents a single imaging component  150  coupled to a front of the UAV  100 , in other implementations, multiple imaging components may be coupled to the UAV at any positions on the UAV. For example, the UAV may include fixed imaging components coupled at each corner junction  131 - 1 ,  131 - 2 ,  131 - 3 ,  131 - 4  and adjustable imaging components coupled to each side of the UAV. 
     The perimeter frame  104  provides safety for objects foreign to the UAV  100  by inhibiting access to the lifting propellers  102  from the side of the UAV  100 , provides protection to the UAV  100 , and increases the structural integrity of the UAV  100 . For example, if the UAV  100  is traveling horizontally and collides with a foreign object (e.g., wall, building), the impact between the UAV  100  and the foreign object will be with the perimeter frame  104 , rather than a propeller. Likewise, because the frame is interconnected with the central frame  107 , the forces from the impact are dissipated across both the perimeter frame  104  and the central frame  107 . 
     The perimeter frame  104  also provides a surface upon which one or more components of the UAV  100  may be mounted. Alternatively, or in addition thereto, one or more components of the UAV may be mounted or positioned within the cavity of the portions of the perimeter frame  104 . For example, antennas may be included in the cavity of the perimeter frame and be used to transmit and/or receive wireless communications. The antennas may be utilized for Wi-Fi, satellite, near field communication (“NFC”), cellular communication, or any other form of wireless communication. Other components, such as cameras, time of flight sensors, accelerometers, inclinometers, distance-determining elements, gimbals, Global Positioning System (GPS) receiver/transmitter, radars, illumination elements, speakers, and/or any other component of the UAV  100  or the UAV control system (discussed below), etc., may likewise be mounted to or in the perimeter frame  104 . Likewise, identification or reflective identifiers may be mounted to the perimeter frame  104  to aid in the identification of the UAV  100 . 
     In some implementations, the perimeter frame  104  may also include a permeable material (e.g., mesh, screen) that extends over the top and/or lower surface of the perimeter frame  104  enclosing the central frame, lifting motors, and/or lifting propellers. 
     A UAV control system  114  is also mounted to the central frame  107 . In this example, the UAV control system  114  is mounted to the hub  108  and is enclosed in a protective barrier. The protective barrier may provide the control system  114  weather protection so that the UAV  100  may operate in rain and/or snow without disrupting the control system  114 . In some implementations, the protective barrier may have an aerodynamic shape to reduce drag when the UAV is moving in a direction that includes a horizontal component. The protective barrier may be formed of any materials including, but not limited to, graphite-epoxy, Kevlar, and/or fiberglass. In some implementations, multiple materials may be utilized. For example, Kevlar may be utilized in areas where signals need to be transmitted and/or received. 
     Likewise, the UAV  100  includes one or more power modules. The power modules may be positioned inside the cavity of the side rails  130 - 1 ,  130 - 2 . In other implementations, the power modules may be mounted or positioned at other locations of the UAV. The power modules for the UAV may be in the form of battery power, solar power, gas power, super capacitor, fuel cell, alternative power generation source, or a combination thereof. For example, the power modules may each be a 6000 mAh lithium-ion polymer battery, or polymer lithium ion (Li-poly, Li-Pol, LiPo, LIP, PLI or Lip) battery. The power module(s) are coupled to and provide power for the UAV control system  114 , the lifting motors  106 , the thrusting motors  110 , and the payload engagement mechanism (not shown). 
     In some implementations, one or more of the power modules may be configured such that it can be autonomously removed and/or replaced with another power module while the UAV is landed or in flight. For example, when the UAV lands at a location, the UAV may engage with a charging member at the location that will recharge the power module. 
     As mentioned above, the UAV  100  may also include a payload engagement mechanism. The payload engagement mechanism may be configured to engage and disengage items and/or containers that hold items (payload). In this example, the payload engagement mechanism is positioned beneath and coupled to the hub  108  of the frame  104  of the UAV  100 . The payload engagement mechanism may be of any size sufficient to securely engage and disengage a payload. In other implementations, the payload engagement mechanism may operate as the container in which it contains item(s). The payload engagement mechanism communicates with (via wired or wireless communication) and is controlled by the UAV control system  114 . Example payload engagement mechanisms are described in U.S. Pat. No. 9,573,684, filed Sep. 30, 2014, titled “UNMANNED AERIAL VEHICLE DELIVERY SYSTEM,” the subject matter of which is incorporated by reference herein in its entirety. 
       FIG. 2  illustrates an imaging component  250  that may be used with and coupled to a UAV, such as the UAV  100  discussed above with respect to  FIG. 1 , according to an implementation. In this example, the imaging component  250  includes three imaging devices, or cameras,  202 - 1 ,  202 - 2 ,  204 , all of which are positioned in the same plane and affixed to a frame at defined baseline distance from one another. Any type of camera and/or configuration of cameras may be used with the implementations described herein. For example, one or more of the cameras may be a red, green, blue (“RGB”) color camera, also referred to herein as a visual light camera, a still camera, a motion capture/video camera or any other type or form of camera. In other implementations, one or more of the cameras may be depth-sensing cameras, such as an RGBz camera. In still other implementations, one or more of the cameras may be a thermographic or infrared (IR) camera. 
     Additionally, in some implementations, the cameras may simply be camera modules that include a lens and an image sensor. The image sensor may convert an optical image obtained by the lens of the camera into a digital signal or digital representation of the image (generally referred to herein as image data). In one implementation, the image sensor may be a RGB sensor capable of supporting an image resolution of at least 860×480 at six frames per second. The image sensor may likewise be configured to provide the image data to other components (e.g., a graphics processing unit) for processing. In some implementations, cameras, such as visual cameras, may be paired to provide stereo imagery and depth information. A stereo camera may include a pair of camera modules. Image data may be stored in any variety of formats including, but not limited to, YUYV, RGB, RAW, .bmp, .jpeg, .gif, or the like. 
     Cameras operate by electronically capturing reflected light from objects and assigning quantitative values to one or more aspects of the reflected light, such as pixels. A camera may include one or more sensors having one or more filters associated therewith. The sensors of a camera may capture information regarding any number of pixels of the reflected light corresponding to one or more base colors (e.g., red, green or blue) expressed in the reflected light, and store values associated with the pixel colors as image data and/or transmit image data to another device for further analysis or reproduction. The camera may also be configured to determine depth information, such as the distance between the camera and an object in the field of view of the camera. Depth information may be included in the image data generated by the camera. 
     Imaging devices such as cameras operate by capturing light that is reflected from objects, and by subsequently calculating or assigning one or more quantitative values to aspects of the reflected light, e.g., pixels, generating an output based on such values, and storing such values in one or more data stores. For example, digital cameras may include one or more sensors having one or more filters associated therewith, and such sensors may detect information regarding aspects of any number of pixels of the reflected light corresponding to one or more base colors (e.g., red, green or blue) of the reflected light. Such sensors may generate data files including such information, and store such data files in one or more onboard or accessible data stores (e.g., a hard drive or other like component), as well as one or more removable data stores (e.g., flash memory devices), or displayed on one or more broadcast or closed-circuit television networks, or over a computer network, such as the Internet. Data files that are stored in one or more data stores may be printed onto paper, presented on one or more computer displays, or subjected to one or more analyses, such as to detect objects represented therein. 
     Reflected light may be captured or detected by an imaging device if the reflected light is within the device&#39;s field of view, which is defined as a function of a distance between a sensor and a lens within the device, viz., a focal length, as well as a location of the device and an angular orientation of the device&#39;s lens. Accordingly, where an object appears within a depth of field, or a distance within the field of view where the clarity and focus is sufficiently sharp, an imaging device may capture light that is reflected off objects of any kind to a sufficiently high degree of resolution using one or more sensors thereof, and store information regarding the reflected light in one or more data files. 
     Thermal imaging, which is generated using thermographic cameras, such as long range IR cameras, detect radiation from an object in the infrared spectrum and produce images of that radiation, called thermograms. Infrared radiation is emitted by all objects with a temperature above absolute zero. The amount of emitted radiation by an object increases with temperature, therefor, thermography allows one to see variation in temperature within a represented scene. 
     Returning to  FIG. 2 , the imaging component  250  in this example includes two paired visual cameras  202 - 1 ,  202 - 2  that are coupled to a frame at fixed positions with respect to one another and separated by a known baseline distance (d 1 ). The two visual cameras  202 - 1 ,  202 - 2  have a similar field of view  206 ,  208 . In other implementations, the two visual cameras may have different fields of view. Regardless, the baseline distance (d 1 ) that separates the two visual cameras and the orientation of the cameras with respect to one another are arranged such that at least a portion of the two fields of view  206 ,  208  overlap to form an effective field of view  210 . Objects positioned within the effective field of view  210  are detectable by both visual cameras  202 - 1 ,  202 - 2  and images formed by the two cameras will both include representations of the object within the effective field of view  210 . 
     During pairing, the two visual cameras  202 - 1 ,  202 - 2  are calibrated such that the pixel information for each camera corresponding to portions within the effective field of view  210  are correlated such that image information within the effective field of view from the two paired cameras can be merged and, with knowledge of the baseline distance (d 1 ), depth information for objects within the field of view may be generated. The depth information may be associated with the corresponding pixel information to form a depth map corresponding to the scene within the effective field of view  210 . In this example, the two visual cameras  202 - 1 ,  202 - 2  are paired and calibrated with the processing component  205 . As images are formed by each of the cameras  202 - 1 ,  202 - 2 , the formed visual images are sent to the processing component  205  and the processing component  205  processes the two images using the calibration information to generate depth information for objects within the effective field of view  210 . The resulting depth information may be associated with the pixels of the images, thereby providing a depth or protrusion of objects above a surface within the scene. 
     In addition to including a pair of visual cameras  202 - 1 ,  202 - 2  for obtaining depth information corresponding to a scene within the effective field of view, the imaging component  250  includes a third camera, in this example a long wave IR camera  204 . In the illustrated example, the third camera is positioned approximately equidistant between the first camera  202 - 1  and the second camera  202 - 2 . By positioning the IR camera  204  between the first camera  202 - 1  and the second camera  202 - 2 , the field of view of the IR camera  204  covers at least a portion of the effective field of view  210 . In the illustrated example, the field of the view of the IR camera  204  covers all of the effective field of view  210 . In other implementations, the third camera may be positioned elsewhere provided that the all three cameras have an overlapping field of view and can be calibrated with respect to one another. For example, the imaging component may include the two visual cameras adjacent one another and the long wave IR camera  204  positioned adjacent only one of the visual cameras. In other implementations, the long wave IR camera  204  may be offset above or below the two visual cameras. 
     When the imaging component  250  is formed, in addition to calibrating the two visual cameras  202 - 1 ,  202 - 2  so that depth information can be obtained, the IR camera  204  is also calibrated so that the pixel information within the effective field of view  210  that is encompassed by the field of view of view of the IR camera  204  is correlated with the pixel information of the IR camera  204 . By calibrating the three cameras  202 - 1 ,  202 - 2 ,  204 , the pixel information from each of the cameras corresponding to the effective field of view  210  is associated and maintained by the processing component  205 . Once calibrated, each pixel information within the effective field of view  210  that corresponds to each of the three cameras  202 - 1 ,  202 - 2 ,  204  includes a horizontal dimension, a vertical dimension, a depth dimension, a thermal dimension (or IR dimension), and optionally, the original pixel value information from the visual light image(s). The horizontal dimension and vertical dimension remain constant for each pixel information and are calibrated across the three cameras. The depth dimension is determined by the processing component  205  and represents a depth of the object represented by the pixel with respect to the imaging component  250 . The thermal dimension is determined by the processing component from the received IR image and represents a radiation of the object represented by the pixel as detected by the IR camera  204 . 
     During operation, images obtained of a scene (e.g., delivery location, landing location, etc.) within the effective field of view  210  by the three cameras  202 - 1 ,  202 - 2 ,  204  are provided to the same processing component  205  of the imaging component  250 . The processing component utilizes the associated pixel information to process the visual images received from the visual cameras  202 - 1  and  202 - 2  to determine depth information corresponding to objects represented in the effective field of view of the two images. Likewise, the processing component  205  utilizes the IR image obtained from the IR camera  204  to determine an IR or thermal representation for each pixel position within the effective field of view. In some implementations, the processing component may correlate a different color of a series of colors and/or value of a series of values to represent thermal radiation detected at different ranges. For example, the processing component  205  may assign one of three different color values to a pixel based on a measured IR for the pixel depending on a range in which the measured IR falls. The horizontal dimension, vertical dimension, depth dimension, and thermal dimension is provided from the processing component to the UAV control system as combined information representative of the scene within the overlapping field of view of the cameras of the imaging component. 
     While the illustrated example utilizes a single processing component  205  that is part of the imaging component  250 , in other implementations the imaging component  250  may include multiple processing components that operate in conjunction or independently to generate the horizontal dimension, vertical dimension, depth dimension, and thermal dimension for each of the pixels within the effective field of view. For example, a first processing component may process the two visual images to determine depth information and a second processing component may process the IR image to determine the thermal dimension. In still other examples, the imaging component  250  may not include a processing component and formed images may be sent directly from the imaging component  250  to other components, such as one or more components of the UAV control system, for further processing. In yet another example, the formed images, and/or determined information (e.g., horizontal dimension, vertical dimension, depth dimension, and/or thermal dimension) may be transmitted from the UAV to another computing system, such as a remote computing system for processing. 
       FIG. 3  illustrates a visual light image  300  of a scene, in this example a delivery location, formed by a camera of the imaging component of  FIG. 2 , according to an implementation. As illustrated, the image  300  is obtained using the imaging component of a UAV while the UAV is aerially positioned above the delivery location. In this example, the scene includes multiple objects, such as tables  306 , chairs  307 , a BBQ grill  310 , lamps  308 ,  316 , a warm-blooded object  314 , in this example a dog, and a large rectangular object  312 . All of the objects are within a scene in which a delivery location identifier  302  is positioned. The delivery location identifier  302  may be used as a beacon or identifier that is detectable by the UAV as an intended delivery location for an item, such as an item ordered by a customer from an electronic commerce website for UAV delivery. 
     To properly detect and avoid objects during a descent of the UAV and ultimate delivery of an item, depth information corresponding to objects within the effective field of view of the imaging component are determined and a depth map is generated. For example,  FIG. 4A  illustrates a depth map  400  of the delivery location, according to an implementation. As discussed above, stereo-paired cameras of the imaging component may be used to generate depth information for the objects represented in the image based on a distance of the objects from the imaging component and/or a distance of the objects from a reference point, such as a surface area. As illustrated, because the protrusion of many objects above the surface are similar, it may be difficult for the UAV control system to accurately determine what is a warm-blooded object and what is not a warm-blooded object. For example, because the warm-blooded object  414  (the dog) protrudes a similar distance from the surface as the chairs  407 , each have a similar depth information representation. In a similar manner, the tables  406  and grill  410  protrude a similar distance and therefore have similar depth information. Likewise, the lamp  416  and the large rectangular object  412  has similar protrusion distances and are similarly represented in the depth map. Finally, because the lamp  408  protrudes well above all other objects it is represented uniquely on the depth map  400 . 
     While a depth map of the objects aids in detection of objects within a represented scene, it is difficult to assess from the depth map which objects are warm-blooded objects that are to be avoided and that may move and/or be injured if contacted by the UAV during descent compared to non-warm-blooded objects that will not move during descent, but need to be avoided. Accordingly, thermal information combined with depth information is beneficial to improve object detection and identification. 
       FIG. 4B  illustrates a thermogram  430  of the delivery location, according to an implementation. Similar to the depth map, the temperate based image may be used to identify objects, not by a protrusion from a surface (or distance from the imaging component) but from radiation emitting from the object. In this example, the tables, chairs, and large rectangular objects, do not emit much radiation and are therefore represented similarly in the thermogram  430 . The BBQ grill  420 , which in this example is in operation, emits a large amount of radiation and is represented differently in the thermogram  400 . Likewise, the warm-blooded object  424  (dog), and the lamps  426 ,  428  also emit radiation and are separately represented in the thermogram  400 . 
     While a thermogram of the objects aids in detection of objects that emit radiation within a represented scene, it is difficult to assess from the thermogram which objects are warm-blooded objects that are to be avoided and that may move and/or be injured if contacted by the UAV during descent compared to non-warm-blooded objects that will not move, but need to be avoided. For example, the lamps  428 ,  426  and/or BBQ grill  420  emit radiation that is similar to that of a warm-blooded animal, such as the warm-blooded object  424  that is detected by the IR camera. 
     By combining the depth information and the thermal information, the accuracy of detecting warm-blooded objects is improved.  FIG. 5  represents a depth and thermal representation  500  of the delivery location, according to an implementation. To aid in illustration, the depth information is presented visually as the objects rather than as a hatch pattern. As shown, the depth of each object protruding above the surface is overlaid with the thermal information determined for each object thereby providing both depth and thermal information for each object within the delivery location. Utilizing the combination of both depth information and thermal information, the accuracy in distinguishing between warm-blooded and non-warm-blooded objects is increased. For example, the tables  506 , chairs  507 , and large rectangular object  512  can be determined to be non-warm-blooded objects because the thermal signature for those objects is lower than that expected for a warm-blooded object. Likewise, the lamp  508  can be determined to be a non-warm-blooded object because it protrudes well above the surface area (e.g., fifteen feet), more than the height expected for a warm-blooded object. 
     The remaining objects, the lamp  516 , BBQ grill  510 , and warm-blooded object  514  may then be avoided as potentially warm-blooded objects. Alternatively, or in addition thereto, additional processing may be performed with respect to those objects. For example, the objects may be monitored for a period of time to assess whether the objects move, thereby indicating that the objects are potentially warm-blooded. As another example, the thermal signature may be further processed to determine if the thermal signature is too high for a warm-blooded object. As another example, the overall shape and thermal signature of the objects may be compared to known shapes and thermal signatures representative of warm-blooded and non-warm-blooded objects to assess whether the object is warm-blooded or non-warm-blooded. 
     As still another example, additional image processing of one or more visual images of the objects may be performed using one or more object detection algorithms in an effort to identify or determine a type of object. In this example, by eliminating many objects using depth information and/or thermal information, the additional image processing required is reduced to only include those objects that could not be eliminated. 
       FIG. 6  is a flow diagram of an example descent analysis process  600 , according to an implementation. This process, and each process described herein, may be implemented by the architectures described herein or by other architectures. The process is illustrated as a collection of blocks in a logical flow. Some of the blocks represent operations that can be implemented in hardware, software, or a combination thereof. In the context of software, the blocks represent computer-executable instructions stored on one or more computer readable media that, when executed by one or more processors, perform the recited operations. Generally, computer-executable instructions include routines, programs, objects, components, data structures, and the like that perform particular functions or implement particular abstract data types. 
     The computer readable media may include non-transitory computer readable storage media, which may include hard drives, floppy diskettes, optical disks, CD-ROMs, DVDs, read-only memories (ROMs), random access memories (RAMs), EPROMs, EEPROMs, flash memory, magnetic or optical cards, solid-state memory devices, or other types of storage media suitable for storing electronic instructions. In addition, in some implementations the computer readable media may include a transitory computer readable signal (in compressed or uncompressed form). Examples of computer readable signals, whether modulated using a carrier or not, include, but are not limited to, signals that a computer system hosting or running a computer program can be configured to access, including signals downloaded through the Internet or other networks. Finally, the order in which the operations are described is not intended to be construed as a limitation, and any number of the described operations can be combined in any order and/or in parallel to implement the process. 
     The example process  600  begins by determining depth information for a represented scene, as in  602 . As discussed above, depth information, or a depth map may be determined based on stereo-paired cameras that form visual images of the scene. The formed visual images are processed together, and utilizing the known baseline between the cameras, depth information for correlated pixels can be determined based on the objects represented in those pixels. In other implementations, other forms or types of devices may be used to determine depth information instead of or in addition to stereo-paired cameras. For example, a distance-determining element, such as a time of flight (ToF) sensor, LASER based range finder, ultrasonic distance meter, etc. may be used to determine depth information for objects within a range or distance of an aerial vehicle. 
     In addition to determining depth information, thermal information for the objects is determined, as in  606 . As discussed above, thermal information may be determined utilizing a thermal imaging camera, such as a long wave IR camera, a medium wave IR camera, a near field IR camera, spectral imaging, etc. The thermal information may be represented as a difference between the thermal signatures of objects in the scene. For example, objects that emit less thermal energy may be represented with one color or value and objects that emit more thermal energy may be represented with a different color or value. 
     The depth information and thermal information is then correlated, as in  606 . For example, the imaging component that is utilized to form images that are used to determine depth information and thermal information may be calibrated such that the horizontal dimension and vertical dimension of each pixel or other form of information generated by each camera is correlated to the same or similar physical position in the represented image. 
     Finally, utilizing the correlated information, combined information that includes the horizontal dimension, vertical dimension, depth dimension, and thermal dimension corresponding to the scene is generated, as in  608 . The combined information may be stored in a data store or other form of memory, presented graphically, and/or otherwise processed. 
       FIG. 7  is a flow diagram of an example descent process  700 , according to an implementation. The example process  700  may be performed during a descent of a UAV toward a location, such as a delivery location. As the UAV is descending, a determination is made as to whether an object protruding above the surface area is detected, as in  702 . In some implementations, the protrusion may only be detected if the object protrudes more than a defined amount above the surface area (e.g., six inches). In other implementations, any protrusion may be detected and processed according to the example process  700 . 
     If it is determined that no protrusion is detected, the descent of the UAV continues, as in  704 , and the example process returns to decision block  702  and continues. However, if it is determined that a protrusion is detected, a determination is made as to whether a thermal dimension corresponding to the detected object exceeds a threshold, as in  706 . The threshold may be any temperature range, may vary for different sizes and/or shapes of objects, vary for different locations, vary for different times of day, and/or vary for any other reason. In some implementations, the threshold may be a threshold difference between a lowest, or average thermal value detected in the represented information and the thermal value for the object determined to protrude above the surface. 
     The threshold may be a value above which a warm-blooded object may be detected. In other implementations, rather than determining whether the thermal signature corresponding to a detected object exceeds a threshold, a temperate range, or thermal difference above a baseline value in the represented information, within which warm-blooded objects may be detected is determined. In such an implementation, the example process  700  may determine whether the thermal signature for the detected object is within the determined temperature range. 
     If it is determined that the thermal dimension does not exceed the threshold, the example process returns to block  704  and continues. However, if it is determined that the thermal dimension exceeds the threshold, a determination is made as to whether a signature of the detected object is known, as in  708 . For example, as objects are detected and determined to be warm-blooded or non-warm-blooded objects, overall signatures of those objects may be maintained in a data store. The overall signature may include a size, shape, protrusion, thermal dimension, etc. for the object. As additional detections of the same object are completed, the data store may be updated and a confidence level increased each time an overall signature of an object is determined to correspond to the same object. This feedback of object detection and overall signature correlation may be performed by multiple UAVs utilizing the example process and the results used by each UAV as part of the example process  700 . For example, each time a UAV of a fleet of UAVs detects an object and determines whether the object is warm-blooded or non-warm-blooded, that information may be provided to remote computing resources that correlate information from all UAVs of the fleet. As information is correlated, an object signature data store representative of all detected objects is developed and maintained by the remote computing resources. That object signature data store may then be provided or otherwise utilized by each UAV of the fleet as part of the example process  700 . 
     Returning to  FIG. 7 , if it is determined that the object signature for the object is not known, the object is avoided during descent and/or the descent may be terminated to avoid any potential interaction between the detected object and the UAV, as in  710 . In some implementations, additional processing of the images and/or the object may be performed in an effort to determine the object. For example, visual images of the object may be processed using one or more object detection algorithms focused on the portion of the image that includes the object. In other examples, the object may be monitored for a period of time to determine whether the object is moving. 
     If it is determined at decision block  708  that the object signature is known, a determination is made as to whether the object is a warm-blooded object, as in  712 . If it is determined that the object is a warm-blooded object, the object is avoided during descent and/or the descent is terminated to avoid any potential interaction between the detected object and the UAV. If it is determined that the object is not a warm-blooded object, i.e., the object is a non-warm-blooded object, the example process  700  returns to block  704  and descent of the UAV continues. In some implementations, if the object is detected and determined to be a non-warm blooded object, a further determination may be made as to whether the detected object is potentially harmful to the UAV and to be avoided at a greater distance than avoiding contact with the object. For example, if the object is determined to have a very high thermal signature, such as a BBQ grill or open flame, it may be determined that a minimum safe distance (e.g., fifteen feet) is to be maintained between the UAV and the object. 
     While the examples discussed above relate to detecting protruding objects and avoiding those objects with thermal signatures that potentially correspond to warm-blooded objects, similar implementations may be used to avoid non-warm-blooded objects that are potentially dangerous landing areas. For example, the implementations discussed herein may be used to detect bodies of water (e.g., pools, ponds, Jacuzzis) that are to be avoided for landing and/or payload delivery. Such detection is possible regardless of whether the body of water protrudes above the surface (such as an above-ground pool) or not. In implementations where the object (body of water) does not protrude above the surface, the depth information may present a substantially flat surface area and the thermal information may indicate that the object is either below an average threshold temperature of other objects in the scene (for cold bodies of water) or above an average threshold temperature (for warm bodies of water). The size, shape, and thermal information provides an indication that the object is a body of water and should not be used for a landing or payload delivery area. 
       FIG. 8  is a block diagram illustrating an example UAV control system  814 . In various examples, the block diagram may be illustrative of one or more aspects of the UAV control system  114  ( FIG. 1 ) that may be used to implement the various systems and methods discussed herein and/or to control operation of the UAVs described herein. In the illustrated implementation, the UAV control system  814  includes one or more processors  802 , coupled to a memory, e.g., a non-transitory computer readable storage medium  820 , via an input/output (I/O) interface  810 . The UAV control system  814  may also include electronic speed controls  804  (ESCs), power supply modules  806 , a navigation system  807 , and/or an object detection controller  812 . In some implementations, the navigation system  807  may include an inertial measurement unit (IMU). The UAV control system  814  may also include a network interface  816 , and one or more input/output devices  818 . 
     In various implementations, the UAV control system  814  may be a uniprocessor system including one processor  802 , or a multiprocessor system including several processors  802  (e.g., two, four, eight, or another suitable number). The processor(s)  802  may be any suitable processor capable of executing instructions. For example, in various implementations, the processor(s)  802  may be general-purpose or embedded processors implementing any of a variety of instruction set architectures (ISAs), such as the x86, PowerPC, SPARC, or MIPS ISAs, or any other suitable ISA. In multiprocessor systems, each processor(s)  802  may commonly, but not necessarily, implement the same ISA. 
     The non-transitory computer readable storage medium  820  may be configured to store executable instructions, data, flight paths, flight control parameters, object signatures, and/or data items accessible by the processor(s)  802 . In various implementations, the non-transitory computer readable storage medium  820  may be implemented using any suitable memory technology, such as static random access memory (SRAM), synchronous dynamic RAM (SDRAM), nonvolatile/Flash-type memory, or any other type of memory. In the illustrated implementation, program instructions and data implementing desired functions, such as those described herein, are shown stored within the non-transitory computer readable storage medium  820  as program instructions  822 , data storage  824  and flight controls  826 , respectively. In other implementations, program instructions, data, and/or flight controls may be received, sent, or stored upon different types of computer-accessible media, such as non-transitory media, or on similar media separate from the non-transitory computer readable storage medium  820  or the UAV control system  814 . Generally speaking, a non-transitory, computer readable storage medium may include storage media or memory media such as magnetic or optical media, e.g., disk or CD/DVD-ROM, coupled to the UAV control system  814  via the I/O interface  810 . Program instructions and data stored via a non-transitory computer readable medium may be transmitted by transmission media or signals, such as electrical, electromagnetic, or digital signals, which may be conveyed via a communication medium such as a network and/or a wireless link, such as may be implemented via the network interface  816 . 
     In one implementation, the I/O interface  810  may be configured to coordinate I/O traffic between the processor(s)  802 , the non-transitory computer readable storage medium  820 , and any peripheral devices, the network interface  816  or other peripheral interfaces, such as input/output devices  818 . In some implementations, the I/O interface  810  may perform any necessary protocol, timing or other data transformations to convert data signals from one component (e.g., non-transitory computer readable storage medium  820 ) into a format suitable for use by another component (e.g., processor(s)  802 ). In some implementations, the I/O interface  810  may include support for devices attached through various types of peripheral buses, such as a variant of the Peripheral Component Interconnect (PCI) bus standard or the Universal Serial Bus (USB) standard, for example. In some implementations, the function of the I/O interface  810  may be split into two or more separate components, such as a north bridge and a south bridge, for example. Also, in some implementations, some or all of the functionality of the I/O interface  810 , such as an interface to the non-transitory computer readable storage medium  820 , may be incorporated directly into the processor(s)  802 . 
     The ESCs  804  communicate with the navigation system  807  and adjust the rotational speed of each lifting motor and/or the thrusting motor to stabilize the UAV and guide the UAV along a determined flight path. The navigation system  807  may include a GPS, indoor positioning system (IPS), IMU or other similar systems and/or sensors that can be used to navigate the UAV  100  to and/or from a location. The object detection controller  812  communicates tithe memory  820  and the imaging device discussed above may be process information and determine if objects are present that are to be avoided and/or if a descent is to be terminated. 
     The network interface  816  may be configured to allow data to be exchanged between the UAV control system  814 , other devices attached to a network, such as other computer systems (e.g., remote computing resources), and/or with UAV control systems of other UAVs. For example, the network interface  816  may enable wireless communication between the UAV that includes the control system  814  and a UAV control system that is implemented on one or more remote computing resources. For wireless communication, an antenna of an UAV or other communication components may be utilized. As another example, the network interface  816  may enable wireless communication between numerous UAVs. In various implementations, the network interface  816  may support communication via wireless general data networks, such as a Wi-Fi network. For example, the network interface  816  may support communication via telecommunications networks, such as cellular communication networks, satellite networks, and the like. 
     Input/output devices  818  may, in some implementations, include one or more displays, imaging devices, thermal cameras, infrared sensors, time of flight sensors, accelerometers, pressure sensors, weather sensors, cameras, gimbals, landing gear, etc. Multiple input/output devices  818  may be present and controlled by the UAV control system  814 . One or more of these sensors may be utilized to assist in landing as well as to avoid obstacles during flight. 
     As shown in  FIG. 8 , the memory may include program instructions  822 , which may be configured to implement the example routines and/or sub-routines described herein. The data storage  824  may include various data stores for maintaining data items that may be provided for determining flight paths, object detection, landing, identifying locations for disengaging items, engaging/disengaging the thrusting motors, etc. In various implementations, the parameter values and other data illustrated herein as being included in one or more data stores may be combined with other information not described or may be partitioned differently into more, fewer, or different data structures. In some implementations, data stores may be physically located in one memory or may be distributed among two or more memories. 
     Those skilled in the art will appreciate that the UAV control system  814  is merely illustrative and is not intended to limit the scope of the present disclosure. In particular, the computing system and devices may include any combination of hardware or software that can perform the indicated functions. The UAV control system  814  may also be connected to other devices that are not illustrated, or instead may operate as a stand-alone system. In addition, the functionality provided by the illustrated components may, in some implementations, be combined in fewer components or distributed in additional components. Similarly, in some implementations, the functionality of some of the illustrated components may not be provided and/or other additional functionality may be available. 
     Those skilled in the art will also appreciate that, while various items are illustrated as being stored in memory or storage while being used, these items or portions of them may be transferred between memory and other storage devices for purposes of memory management and data integrity. Alternatively, in other implementations, some or all of the software components may execute in memory on another device and communicate with the illustrated UAV control system  814 . Some or all of the system components or data structures may also be stored (e.g., as instructions or structured data) on a non-transitory, computer-accessible medium or a portable article to be read by an appropriate drive. In some implementations, instructions stored on a computer-accessible medium separate from the UAV control system  814  may be transmitted to the UAV control system  814  via transmission media or signals such as electrical, electromagnetic, or digital signals, conveyed via a communication medium such as a wireless link. Various implementations may further include receiving, sending, or storing instructions and/or data implemented in accordance with the foregoing description upon a computer-accessible medium. Accordingly, the techniques described herein may be practiced with other UAV control system configurations. 
     Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as exemplary forms of implementing the claims.