Patent Publication Number: US-2021171195-A1

Title: Unmanned aerial vehicle and waterproof container

Description:
TECHNICAL FIELD 
     The present invention relates to an unmanned aerial vehicle and a waterproof container. 
     BACKGROUND ART 
     It is expected that opportunities of using an unmanned aerial vehicle (drone) for transport on the sea increase in the future. There exist drones including a float such as a member having buoyancy (for example, foaming polystyrol) or a hollow air chamber (WO 2018/042610 and Japanese Patent Application Laid-open No. 2015-117003). 
     CITATION LIST 
     Patent Literature 
     [PTL 1] WO2018/042610A1 
     [PTL 2] JP 2015-117003 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     It is desired that the float be as small as possible. However, in order to deal with transport of a large package, a large float is required. In view of such a circumstance, it is desired that a container be utilized as a float. However, a container does not function as a float unless the container is completely and hermetically sealed. Further, the container cannot maintain waterproofness unless a door of the container is completely closed. 
     One or more embodiments of the present invention are directed to secure hermetic sealing of a container. 
     Solution to Problem 
     (1) An unmanned aerial vehicle according to one or more embodiments of the present invention is an unmanned aerial vehicle including a waterproof container configured to accommodate a package, the waterproof container including: a container main body having an opening in a bottom surface defined in a landed state of the unmanned surface aerial vehicle; a waterproof door mounted to the container main body so as to open outward and close the opening; an elastic seal, which is interposed between the container main body and the waterproof door, and is configured to close the waterproof door in a liquid-tight manner; a first door-closing mechanism configured to retain a first door-closing state of the waterproof door; and a second door-closing mechanism configured to prevent movement of the waterproof door in a door-opening direction in a second door-closing state in which the waterproof door has been pushed in a direction of resisting against an elastic force of the elastic seal from the first door-closing state. 
     According to one or more embodiments of the present invention, when the waterproof door is pushed by an external force, hermetic sealing with the waterproof door can be enhanced from the first door-closing state to the second door-closing state, thereby being capable of securing the hermetic sealing of the waterproof container. 
     (2) The unmanned aerial vehicle according to Item (1), the waterproof door may be a double door including a first door and a second door. 
     (3) In the unmanned aerial vehicle according to Item (1) or (2), the elastic seal may be interposed also between the first door and the second door. 
     (4) In the unmanned aerial vehicle according to any one of Items (1) to (3), the first door-closing mechanism and the second door-closing mechanism may be included in a locking mechanism having a plurality of locking levels. 
     (5) In the unmanned aerial vehicle according to any one of Items (1) to (4), the unmanned aerial vehicle may further include a pressure adjustment valve mounted to the container main body. 
     (6) In the unmanned aerial vehicle according to any one of Items (1) to (5), the waterproof door may include a float. 
     (7) In the unmanned aerial vehicle according to any one of Items (1) to (6), the waterproof door may include: a first-side end portion extending along a rotation shaft for opening and closing; and a second-side end portion located on a side opposite to the first-side end portion, and an outer surface of the waterproof door may be a surface generated by translation of the rotation shaft and be inclined toward the first-side end portion. 
     (8) In the unmanned aerial vehicle according to Item (7), the outer surface may be a curved surface. 
     (9) In the unmanned aerial vehicle according to any one of Items (1) to (8), the unmanned aerial vehicle may further include a parachute. 
     (10) In the unmanned aerial vehicle according to any one of Items (1) to (9), the unmanned aerial vehicle may further include a radio configured to perform at least one of transmission or reception of signals. 
     (11) A waterproof container according to one or more embodiments of the present invention is a waterproof container including: a container main body having an opening in a bottom surface; a waterproof door, which is mounted to the container main body so as to open outward and close the opening, and is a double waterproof door including a first door and a second door; an elastic seal, which is interposed between the first door and the container main body and between the second door and the container main body, and is configured to close the waterproof door in a liquid-tight manner; a first door-closing mechanism configured to retain a first door-closing state of each of the first door and the second door; and a second door-closing mechanism configured to prevent movement of the first door and the second door in respective door-opening directions in a second door-closing state in which the first door and the second door are each pushed in a direction of resisting against an elastic force of the elastic seal from the first door-closing state. 
     According to one or more embodiments of the present invention, when the waterproof door is pushed by an external force, hermetic sealing with the waterproof door is enhanced from the first door-closing state to the second door-closing state. With this, the hermetic sealing of the waterproof container can be secured. 
     (12) In the waterproof container according to (11), the elastic seal may be interposed also between the first door and the second door. 
     (13) In the waterproof container according to (11) or (12), the first door-closing mechanism and the second door-closing mechanism may be included in a locking mechanism having a plurality of locking levels. 
     (14) In the waterproof container according to any one of Items (11) to (13), the waterproof container may further include a pressure adjustment valve mounted to the container main body. 
     (15) In the waterproof container according to any one of Items (11) to (14), the first door and the second door may each include a float. 
     (16) In the waterproof container according to any one of Items (11) to (15), the first door and the second door may each include: a first-side end portion extending along a rotation shaft for opening and closing; and a second-side end portion located on a side opposite to the first-side end portion, and wherein an outer surface of each of the first door and the second door may be a surface generated by translation of the rotation shaft and may be inclined toward the first-side end portion. 
     (17) In the waterproof container according to Item (16), the inclined surface may be a curved surface. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a plan view of an unmanned aerial vehicle according to an embodiment. 
         FIG. 2  is a side view of the unmanned aerial vehicle illustrated in  FIG. 1 . 
         FIG. 3  is a functional block diagram of an apparatus main body. 
         FIG. 4  is a side view for illustrating details of a waterproof container. 
         FIG. 5  is a sectional view of the waterproof container illustrated in  FIG. 4 , which is taken along the line V-V. 
         FIG. 6  is a view for illustrating a state in which a waterproof door is opened. 
         FIG. 7  is a view for illustrating a second door-closing state of the waterproof door. 
         FIG. 8  is a view for illustrating a first modification example of the unmanned aerial vehicle according to the embodiment. 
         FIG. 9  is a view for illustrating a second modification example of the unmanned aerial vehicle according to the embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Now, embodiments of the present invention are described with reference to the drawings. The present invention can be implemented by various modes without departing from the gist of the present invention, and is not to be construed as being limited to the contents of exemplary embodiments described below. 
       FIG. 1  is a plan view of an unmanned aerial vehicle according to an embodiment of the present invention.  FIG. 2  is a side view of the unmanned aerial vehicle illustrated in  FIG. 1 . In the following description, an X1 direction and an X2 direction are referred to as “right” and “left”, respectively. A Y1 direction and a Y2 direction are referred to as “front” and “back”, respectively. A direction extending along a plane defined by X1-X2 and Y1-Y2 is referred to as “horizontal direction”. A Z1 direction and a Z2 direction are referred to as “up” and “down”, respectively. 
     The unmanned aerial vehicle is to be used for transportation of a package  10  such as containing, for example, consumer necessities, foods, electronic devices, or books. Delivery destinations include an isolated island, and flight paths include paths above water, such as the sea, a river, and a lake. The unmanned aerial vehicle may be remotely controlled by a radio system, or may autonomously fly after a target position (landing position) is designated. 
     The unmanned aerial vehicle is a multicopter capable of taking off and landing in a vertical direction. The unmanned aerial vehicle includes a plurality of propellers  12  and a plurality of motors  14 . The motors  14  are configured to rotate the propellers  12 , respectively. The motors  14  may be located at positions directly under centers of the propellers  12  or may be located at positions which are not directly under the centers of the propellers  12 . The propellers  12  and the motors  14  are arranged at equal intervals in a circumferential direction about an apparatus main body  16 . The unmanned aerial vehicle includes the apparatus main body  16  at a center portion thereof. 
     The unmanned aerial vehicle includes a plurality of support arms  18  extending from the apparatus main body  16  in the horizontal direction. The support arms  18  support the motors  14  at positions apart from the apparatus main body  16 . The support arms  18  include extension portions  20  further extending from the positions of the motors  14 . The extension portions  20  support, at respective end portions thereof, a guard cable  22  surrounding the entirety of the plurality of propellers  12 . 
     The unmanned aerial vehicle includes a support frame  24 . The support frame  24  includes a frame upper portion  28  and a frame lower portion  30 . The frame upper portion  28  is configured to support, for example, the apparatus main body  16  and batteries  26 . The frame lower portion  30  extends downward from the frame upper portion  28 . The frame upper portion  28  includes two horizontal bars  32 , which are apart from each other in the right-and-left direction and extend in the horizontal direction. 
     The frame lower portion  30  includes a plurality of leg portions  34  extending downward from the horizontal bars  32 . The frame lower portion  30  includes a plurality of lower-end bars  36 , which extend in the horizontal direction and are connected to respective lower ends of the plurality of leg portions  34 . Lower ends of the frame lower portion  30  (that is, the lower-end bars  36 ) are located below a lower end of a waterproof container  50  described later, to thereby support the unmanned aerial vehicle on the ground and prevent contact between the waterproof container  50  and the ground at the time of landing of the unmanned aerial vehicle. 
     The structure of the support frame  24  is not limited to the example described above. For example, the support frame  24  may include a plate-like support base on which the batteries  26  and the apparatus main body  16  are mounted, and the leg portions  34  may extend downward from the support base. 
     The unmanned aerial vehicle includes one or a plurality of batteries  26 . The motors  14  are driven by electric power supplied from the batteries  26 . The batteries  26  are arranged at the center portion of the unmanned aerial vehicle. The batteries  26  are supported by the support frame  24  provided at the center portion of the unmanned aerial vehicle. 
       FIG. 3  is a functional block diagram of the apparatus main body  16 . The apparatus main body  16  includes a control device  38 , motor driving devices  40 , a radio  42 , and sensors  44 . The apparatus main body  16  includes a housing  46  ( FIG. 1  and  FIG. 2 ) configured to accommodate, for example, the control device  38  and the radio  42 . Moreover, the apparatus main body  16  may include, besides the batteries  26  for driving the motors  14 , a battery configured to store electric power to be supplied to the control device  38 . 
     The sensors  44  include, for example, a 3-axis gyrosensor and a 3-axis acceleration sensor. The 3-axis gyrosensor is configured to output, for example, signals associated with a pitch angle, a roll angle, and a yaw angle of the unmanned aerial vehicle. The 3-axis acceleration sensor is configured to output signals associated with acceleration of the unmanned aerial vehicle, specifically, acceleration in the front-and-back direction, acceleration in the right-and-left direction, and acceleration in the up-and-down direction. Kinds of sensors included in the sensors  44  are not limited to the 3-axis gyrosensor and 3-axis acceleration sensor. For example, the sensors  44  may further include a geomagnetic sensor configured to output signals associated with directions of the unmanned aerial vehicle. 
     The radio  42  is a device configured to perform at least one of transmission or reception of signals. The radio  42  includes, for example, a global positioning system (GPS) receiver. The radio  42  includes a beacon transmitter configured to emit beacons which are, for example, signals including positional information of itself. Through use of the beacons, a position of a missing unmanned aerial vehicle can be identified, and the unmanned aerial vehicle can be promptly collected. 
     The radio  42  may include a receiver configured to receive commands from an external operation input device (not shown) and a transmitter configured to transmit a state of the unmanned aerial vehicle to the external operation input device. The external operation input device is, for example, a personal computer or a single-purpose input device to be operated by a user of the unmanned aerial vehicle (operator who monitors flight). The radio  42  outputs contents of the received signals to the control device  38  or transmits signals acquired from the control device  38 . The unmanned aerial vehicle may include an antenna  48  to which the radio  42  is connected. The antenna  48  is mounted, for example, on the top of the apparatus main body (see  FIG. 2 ). 
     The motor driving devices  40  receive electric power from the batteries  26  and supply the electric power to the motors  14  based on command values received from the control device  38 . The motors  14  rotate at respective speeds which are determined based on the electric power (voltage) supplied from the motor driving devices  40 . The unmanned aerial vehicle includes motor driving devices  40  provided respectively for the plurality of motors  14 . 
     The control device  38  includes a storage device and a microprocessor configured to execute a program stored in the storage device. The control device  38  is configured to control the motors  14  based on signals (information) input from the sensors  44  and signals (information) input from the radio  42 . The control device  38  controls respective rotation speeds of the plurality of motors  14  based on the signals input from the sensors  44 , to thereby control a posture (pitch angle, roll angle, and yaw angle) and a movement (forward, backward, upward, downward, leftward, and rightward movements) of the unmanned aerial vehicle. 
     The control device  38  may determine whether or not the unmanned aerial vehicle has landed on water or the ground. Then, when it is determined that the unmanned aerial vehicle has landed on water or the ground, the control device  38  may transmit information regarding the fact of landing through the radio  42 . 
     It is not always required that the components of the apparatus main body  16  be accommodated in the housing  46  in common. For example, a housing configured to accommodate the motor driving devices  40  and a housing configured to accommodate the control device  38  and the radio  42  may be separately provided. Moreover, a housing configured to accommodate the control device  38  and a housing configured to accommodate the radio  42  may also be separately provided. 
     It is desired that the housing (for example, the housing  46 ) configured to accommodate, for example, the motors  14 , the batteries  26 , the sensors  44 , and the control device  38  have a waterproof function. With such a configuration, malfunction of the unmanned aerial vehicle can be avoided even when the unmanned aerial vehicle is capsized after landing on water. 
     The unmanned aerial vehicle includes a waterproof container  50  (see  FIG. 2 ) configured to accommodate the package  10 . The waterproof container  50  has, for example, a rectangular parallelepiped shape. The waterproof container  50  is mounted to the support frame  24 . For example, the waterproof container  50  is mounted on a lower side of the frame upper portion  28 . The waterproof container  50  is located on an inner side of the plurality of leg portions  34 . The apparatus main body  16  is located on an upper side of the waterproof container  50 . 
     The waterproof container  50  has a liquid-tight configuration. That is, the waterproof container  50  has such a configuration as to prevent entry of water from an outside to an inside of the waterproof container  50 . With the liquid-tight configuration of the waterproof container  50 , buoyancy of the waterproof container  50  can be obtained when the unmanned aerial vehicle lands on water. 
       FIG. 4  is a side view for illustrating details of the waterproof container  50 .  FIG. 5  is a sectional view of the waterproof container  50  illustrated in  FIG. 4 , which is taken along the line V-V. The waterproof container  50  includes a container main body  52 . The container main body  52  is made of a watertight material such as carbon, plastic, or metal. 
     A pressure adjustment valve  54  (for example, a check valve) is mounted to the container main body  52 . The pressure adjustment valve  54  is configured to discharge gas when internal pressure increases, and may be configured to automatically close at an appropriate internal pressure. 
     The container main body  52  has an opening  56  in a bottom surface defined in a landed state of the unmanned aerial vehicle, allowing the package  10  ( FIG. 2 ) to be placed in and taken out through the opening  56 . A waterproof door  58  is mounted to the container main body  52  so that the opening  56  can be closed. The waterproof door  58  may be opened and closed by hand or by an actuator (not shown). 
     The waterproof door  58  includes door main bodies  60 . The door main bodies  60  are each made of a watertight material such as carbon, plastic, or metal. The waterproof door  58  includes floats  62 . For example, the floats  62  are affixed on an outer side of the door main bodies  60 . The floats  62  are each, for example, a resin foam body or a bag or a box filled with gas. Examples of the resin foam body include foaming polystryrene and polyvinyl chloride foam. The floats  62  are not limited to the example of forming an entire outer surface of the waterproof door  58 , and positions and shapes of the floats  62  can be modified. 
       FIG. 6  is a view for illustrating a state in which the waterproof door  58  is opened. The waterproof door  58  is configured to open outward, and is a double door including a first door  58 A and a second door  58 B. The waterproof door  58  (each of the first door  58 A and the second door  58 B) includes a first-side end portion  66  and a second-side end portion  68 . The first-side end portion  66  extends along a rotation shaft  64  for opening and closing. The second-side end portion  68  is located on a side opposite to the first-side end portion  66 . An outer surface (surface of the float  62 ) of the waterproof door  58  (each of the first door  58 A and the second door  58 B) is a surface generated by translation of the rotation shaft  64  and is inclined toward the first-side end portion  66 . The outer surface is a curved surface. 
     The waterproof container  50  includes an elastic seal  70  configured to close the waterproof door  58  in a liquid-tight manner. The elastic seal  70  is interposed between the container main body  52  and the waterproof door  58 . The elastic seal  70  is compressed (elastically deformed) between the container main body  52  and the waterproof door  58 . With this, a gap between the container main body  52  and the waterproof door  58  is eliminated, and hence a liquid-tight state is achieved. 
     An elastic seal  72  (for example, first elastic seal  72 A and second elastic seal  72 B) is interposed also between the first door  58 A and the second door  58 B. The first elastic seal  72 A has a recess, and the second elastic seal  72 B has a protrusion. The recess of the first elastic seal  72 A and the protrusion of the second elastic seal  72 B are fitted to each other. As illustrated in  FIG. 6 , a side wall is inclined so that the recess is widened, and hence the protrusion is easily fitted to the recess. In the example of  FIG. 6 , floats are not provided under the first elastic seal  72 A and the second elastic seal  72 B. However, the floats may be provided. 
     The waterproof container  50  includes locking mechanisms  74  (for example, latches) for the waterproof door  58 . The locking mechanisms  74  are provided to the container main body  52  (on both sides along the rotation shafts  64 ) at positions corresponding to the second-side end portions  68  of the closed waterproof door  58  (on the side opposite to the rotation shafts  64 ) as illustrated in  FIG. 5 . The locking mechanisms  74  each include a locking component  78  having a plurality of claws  76  (first claw  76 A and second claw  76 B) arranged next to each other. The locking component  78  is held by a mounting portion  80  for mounting to the container main body  52  so that only linear movement in a direction D along the rotation shaft  64  is allowed. Moreover, the locking component  78  is provided on an outer side of the waterproof door  58 , and a spring  82  is compressed so that a force in a direction of approaching the waterproof door  58  acts on the locking component  78 . 
     When the waterproof door  58  is closed, a part of the waterproof door  58  (engagement portion  84 ) is brought into abutment against an inclined outer surface  86  of the first claw  76 A. The inclined outer surface  86  is inclined with respect to the direction of the linear movement of the locking component  78 . The inclined outer surface  86  is inclined in a direction toward an opening/closing path of the waterproof door  58 . Therefore, when the engagement portion  84  of the waterproof door  58  pushes the outer surface, the locking component  78  moves in a direction of separating away from the waterproof door  58  against a force of the spring  82 . Then, the engagement portion  84  is engaged with an inner surface  88  of the first claw  76 A. The inner surface  88  is, for example, parallel to the direction of the linear movement of the locking component  78 , and is not inclined. 
     A pin  90  is mounted to the locking component  78 . The engagement between the first claw  76 A and the engagement portion  84  can be canceled by pulling the pin  90  in the direction of separating away from the waterproof door  58  against the force of the spring  82 . 
     The waterproof container  50  includes a first door-closing mechanism  92  (for example, the first claw  76 A). The first door-closing mechanism  92  is included in the locking mechanism  74  having a plurality of locking levels (two or more locking levels). A first door-closing state of the waterproof door  58  is retained by the first door-closing mechanism  92 . As illustrated in  FIG. 4 , a state in which the first door  58 A and the second door  58 B are engaged with the first claws  76 A ( FIG. 5 ) is the first door-closing state. In the first door-closing state, the compression of the elastic seal  70  is small, and hence hermetic sealing is insufficient in some cases. 
       FIG. 7  is a view for illustrating a second door-closing state of the waterproof door  58 . The waterproof container  50  includes a second door-closing mechanism  94  (for example, the second claw  76 B). The second door-closing mechanism  94  is included in the locking mechanism  74  having a plurality of locking levels. In the second door-closing state, the second door-closing mechanism  94  prevents movement of the waterproof door  58  in a door-opening direction. The second door-closing state is a state in which the waterproof door  58  has been pushed in a direction of resisting against an elastic force of the elastic seal  70  from the first door-closing state. For example, in some cases, the waterproof door  58  is pushed when the unmanned aerial vehicle lands on water. 
     According to this embodiment, when the waterproof door  58  is pushed by the external force, the hermetic sealing with the waterproof door  58  can be enhanced from the first door-closing state to the second door-closing state, thereby being capable of securing the hermetic sealing of the waterproof container  50 . In particular, when the outer surface of the waterproof door  58  is the curved surface, the external force is more likely to act in a direction of enhancing the hermetic sealing. Examples of the external force include impact generated by collision between the waterproof door  58  and water and buoyancy generated in the floats  62 . 
       FIG. 8  is a view for illustrating a first modification example of the unmanned aerial vehicle according to the embodiment. The hermetic sealing with the waterproof door  58  described above can be enhanced when the unmanned aerial vehicle lands on water. However, it is desired that the unmanned aerial vehicle land on water under a state in which the waterproof door  58  is oriented downward. Therefore, the unmanned aerial vehicle includes a parachute  196  as illustrated in  FIG. 8 . The parachute  196  is configured to open, for example, when abnormality of the unmanned aerial vehicle is detected. With this, the waterproof container  50  can land on water under the state in which the waterproof door  58  is oriented downward, that is, while the unmanned aerial vehicle takes a horizontal posture or a posture close to the horizontal posture. 
       FIG. 9  is a view for illustrating a second modification example of the unmanned aerial vehicle according to the embodiment. In this example, a first door-closing mechanism  292  (for example, first claw  276 A) and a second door-closing mechanism  294  (for example, second claw  276 B) are provided around a rotation shaft  264  of a waterproof door  258 . When the waterproof door  258  is opened or closed, the first claw  276 A and the second claw  276 B move around the rotation shaft  264 . 
     Movement of the first claw  276 A and the second claw  276 B in a direction of opening the waterproof door  258  is prevented by an engagement portion  284 . The engagement portion  284  is formed integrally with a lever  298 . The lever  298  is mounted to a container main body  252  so as to be swingable about a shaft extending parallel to the rotation shaft  264  of the waterproof door  258 . Moreover, a force in a direction in which the engagement portion  284  approaches the first claw  276 A and the second claw  276 B is caused to act on the lever  298  by an extended spring  282 . When the waterproof door  258  moves in a closing direction, the lever  298  swings so as to cause the engagement portion  284  to be pushed up by the first claw  276 A and the second claw  276 B. With this, the waterproof door  258  can be closed without being regulated by the engagement portion  284 . In order to cancel the first door-closing state or the second door-closing state, it is only required that the lever  298  be moved in a direction in which the engagement portion  284  separates away from the first claw  276 A or the second claw  276 B. Moreover, the lever  298  penetrates the container main body  252 . Therefore, the penetrating part is covered with a cover  200  for waterproofing. 
     The present invention is not limited to the embodiment described above, and various modifications may be made thereto. For example, the structure described in the embodiment may be replaced by substantially the same structure, a structure having the same action and effect, and a structure which may achieve the same object.