Patent Publication Number: US-2020298399-A1

Title: Charging device, charging method, and charging system

Description:
TECHNICAL FIELD 
     The present disclosure relates to a charging device, a charging method, and a charging system. 
     BACKGROUND ART 
     Patent Document 1 below conventionally discloses a robot device capable of not only walking on four legs but also standing on two hind legs. 
     CITATION LIST 
     Patent Document 
     
         
         Patent Document 1: JP 2004-66381 A 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     An electric robot device needs to be appropriately charged. On the other hand, in a method of charging the robot device by connecting a power line thereto, there is a problem that a user needs to perform a complicated operation to connect the power line to the robot. 
     In addition, in a case where it is assumed that the robot device is connected to a charging station for charging, it is difficult to accurately align the robot device with the charging station. 
     Therefore, it has been required to reliably connect a device to be charged such as a robot and a charging device. 
     Solutions to Problems 
     According to the present disclosure, there is provided a charging device including: a charging stand having a charging terminal to be connected to a device to be charged and an engaging portion that performs positioning with the device to be charged; and a support member that supports the charging stand movably in the horizontal direction. 
     In addition, according to the present disclosure, there is provided a charging method in a charging device including a charging stand having a charging terminal to be connected to a device to be charged and an engaging portion that performs positioning with the device to be charged, and a support member that supports the charging stand movably in the horizontal direction, the charging method including: positioning the device to be charged on the charging stand; and electrically connecting the charging terminal and a terminal of the device to be charged by lowering the device to be charged. 
     In addition, according to the present disclosure, there is provided a charging system including: a movable device to be charged; and a charging device including a charging stand having a charging terminal to be connected to a device to be charged and an engaging portion that performs positioning with the device to be charged, and a support member that supports the charging stand movably in the horizontal direction. 
     Effects of the Invention 
     According to the present disclosure, it is possible to reliably connect a device to be charged such as a robot and a charging device. 
     Note that the above effect is not necessarily limiting, and in conjunction with or in place of the above effect, any of the effects shown in the present specification, or other effects that may be understood from the present specification, may be achieved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic view illustrating an appearance of a charging station according to an embodiment of the present disclosure. 
         FIG. 2  is a schematic view illustrating the appearance of the charging station according to the embodiment of the present disclosure. 
         FIG. 3  is a schematic view illustrating a robot to be charged by the charging station. 
         FIG. 4A  is a schematic view illustrating the robot riding on the charging station and self-charging. 
         FIG. 4B  is a schematic view illustrating the robot riding on the charging station and self-charging. 
         FIG. 5  is a schematic view illustrating a fitting surface provided on a belly of the robot. 
         FIG. 6  is an enlarged schematic view illustrating the fitting surface and its periphery of the robot. 
         FIG. 7  is a schematic view for describing how the fitting surface of the robot and a fitting surface of a charging stand fit together. 
         FIG. 8  is a schematic view for describing how the fitting surface of the robot and the fitting surface of the charging stand fit together. 
         FIG. 9  is a schematic view for describing how the fitting surface of the robot and the fitting surface of the charging stand fit together. 
         FIG. 10  is a schematic view for describing how the fitting surface of the robot and a fitting surface of a charging stand fit together. 
         FIG. 11  is a schematic view illustrating the charging stand removed from a charging mat. 
         FIG. 12  is a schematic view illustrating the bottom surface of the charging stand. 
         FIG. 13  is a schematic view illustrating the charging mat with the charging stand removed. 
         FIG. 14  is a schematic view for describing horizontal movement of the charging stand. 
         FIG. 15  is a schematic view illustrating a mechanism of a movable part that enables movement in a transverse direction A 3 , a longitudinal direction A 4 , and rotation directions A 5  and A 6  illustrated in  FIG. 14 . 
         FIG. 16  is a schematic view illustrating an example in which a groove having the shape similar to the shape of the bottom of a paw of the robot is provided along an edge of the charging mat. 
         FIG. 17  is a schematic view illustrating a cross section of the charging station illustrated in  FIG. 16  taken along a line similar to a one-dot chain line I-I′ in  FIG. 7 . 
         FIG. 18A  is a schematic view illustrating the charging stand having a circular planar shape. 
         FIG. 18B  is a schematic view illustrating a cross section taken along a one-dot chain line III-III′ in  FIG. 18A . 
         FIG. 19A  is a schematic view illustrating a fitting surface  502  of the robot to be connected to the charging stand illustrated in  FIGS. 18A and 18B . 
         FIG. 19B  is a schematic view illustrating the fitting surface  502  of the robot to be connected to the charging stand illustrated in  FIGS. 18A and 18B . 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Note that, in the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference signs, and redundant description thereof is omitted. 
     Note that the description will be made in the following order. 
     1. Appearance of Charging Device 
     2. Appearance of Robot 
     3. Example of Self-Charging Posture 
     4. Connection between Charging Station and Robot 
     5. Configurations of Charging Stand and Charging Mat 
     1. Appearance of Charging Device 
       FIGS. 1 and 2  are schematic views illustrating an appearance of a charging station  1000  according to an embodiment of the present disclosure. The charging station  1000  is configured to enable a robot  500  to perform self-charging. As illustrated in  FIGS. 1 and 2 , the charging station  1000  includes a charging stand  100  and a charging mat (support member)  200 . As illustrated in  FIG. 2 , power is supplied to the charging station  1000  by insertion of an AC adapter plug  300  into the charging mat  200 . 
     2. Appearance of Robot 
       FIG. 3  is a schematic view illustrating the robot (device to be charged)  500  to be charged by the charging station  1000 . In the present embodiment, the robot  500  is a dog-shaped robot, and can move around freely by walking on four legs. For this reason, on a joint of the leg of the robot  500 , an actuator that drives the joint is mounted. The robot  500  is appropriately charged to drive the actuator. By recognizing the charging station  1000 , and moving to a position of the charging stand station  1000  to contact the charging stand  100 , the robot  500  can perform charging on its own will (hereinafter also referred to as self-charging). 
     3. Example of Self-Charging Posture 
       FIGS. 4A and 4B  are schematic views illustrating the robot  500  riding on the charging station  1000  and self-charging. Examples of the posture in which the robot  500  performs charging include a “dive” posture illustrated in  FIG. 4A  and a “sitting” posture illustrated in  FIG. 4B . In both postures, charging is performed when a connection terminal on the robot  500  side contacts a connection terminal on the charging stand  100  side. 
     In normal charging, charging is performed in the “sitting” posture illustrated in  FIG. 4B . On the other hand, in a case where a charge amount of the robot  500  is extremely small, for example, the robot  500  quickly rides on the charging station  1000  and dives onto the charging stand  100  for charging. In a case where such a dive operation is performed, self-charging is performed in the posture illustrated in  FIG. 4A . 
     4. Connection between Charging Station and Robot 
     As illustrated in  FIGS. 1 and 2 , the charging stand  100  has a curved fitting surface  102  that matches the shape of a fitting surface  502  of the robot  500  so that the charging stand  100  can be fitted with the robot  500 . The fitting surface  502  on the robot  500  side is provided on a belly portion of the robot  500 .  FIG. 5  is a schematic view illustrating the fitting surface  502  provided on the belly of the robot  500 . In addition,  FIG. 6  is an enlarged schematic view illustrating the fitting surface  502  and its periphery of the robot  500 . 
     The charging stand  100  of the charging station  1000  is provided with charging terminals  104 ,  106 , and  108  so as to be surrounded by the fitting surface  102 . When the robot  500  performs charging, the charging terminals  104 ,  106 , and  108  are connected to charging terminals  504 ,  506 , and  508  on the robot side illustrated in  FIGS. 5 and 6 . 
     A terminal protection plate  110  is provided to protect the charging terminals  104 ,  106 , and  108 . The charging terminals  104 ,  106 , and  108  are protected by the terminal protection plate  110  in a case where the robot  500  is not charging. When the robot  500  sits down and the fitting surface  502  and the fitting surface  102  are brought into close contact with each other, the terminal protection plate  110  is lowered by the weight of the robot  500 , so that the charging terminals  104 ,  106 , and  108  appear. In addition, in a case where the robot  500  is not charging, that is, in a case where the fitting surface  502  and the fitting surface  102  are not in close contact with each other, the terminal protection plate  110  is pushed upward by a compression coil spring. With this arrangement, the upper surfaces of the charging terminals  104 ,  106 , and  108  become lower than the upper surface of the terminal protection plate  110 , so that the charging terminals  104 ,  106 , and  108  can be protected. 
     As illustrated in  FIG. 6 , positioning protrusions (engaging portions)  512  and  514  are provided on the fitting surface  502  of the robot  500 . In addition, as illustrated in  FIGS. 1 and 2 , the charging stand  100  is provided with positioning recesses  112  and  114  corresponding to the positioning protrusions  512  and  514 , respectively. A positional relationship between the positioning protrusions  512  and  514  and the charging terminals  504 ,  506 , and  508  on the fitting surface  502  is similar to a positional relationship between the positioning recesses  112  and  114  and the charging terminals  104 ,  106 , and  108  on the fitting surface  102 . 
     When the robot  500  sits down on the charging stand  100 , the positioning protrusions  512  and  514  illustrated in  FIG. 6  are pressed onto the fitting surface  102 . The positioning protrusions  512  and  514  on the robot side are fitted into the positioning recesses  112  and  114  of the charging stand  100 , so that the charging terminals  104 ,  106 , and  108  on the charging stand  100  side can be joined to the charging terminals  504 ,  506 , and  508  on the robot  500  side. 
       FIGS. 7 to 10  are schematic views for describing how the fitting surface  502  of the robot  500  and the fitting surface  102  of the charging stand  100  fit together.  FIG. 7  is a plan view of the charging station  1000  as viewed from above.  FIG. 8  schematically illustrates a cross section taken along a one-dot chain line I-I′ in  FIG. 7 . 
     In addition,  FIG. 9  schematically illustrates a cross section taken along a one-dot chain line II-II′ in  FIG. 7 , and illustrates, together with the charging station  1000 , a cross section of the robot  500  in the vicinity of the fitting surface  502 . More specifically,  FIG. 9  illustrates the fitting surface  102  of the charging stand  100  and the fitting surface  502  of the robot  500  in a state of being in close contact with each other, and the positioning protrusions  512  and  514  in a state of being fitted into the positioning recesses  112  and  114 . 
     In addition,  FIG. 10  schematically illustrates a cross section taken along the one-dot chain line I-I′ in  FIG. 7 , and illustrates, together with the charging station  1000 , a cross section of the robot  500  in the vicinity of the fitting surface  502 . More specifically,  FIG. 10  illustrates the fitting surface  502  of the robot  500  in a state of being fitted into the fitting surface  102  of the charging stand  100 . 
     As illustrated in  FIGS. 8 to 10 , the fitting surface  102  of the charging stand  100  includes a concave curved surface in both the cross section taken along the one-dot chain line I-I′ and the cross section taken along the one-dot chain line II-II′. The fitting surface  502  of the robot  500  includes a curved surface having the shape corresponding to the shape of the fitting surface  102  of the charging stand  100 , and includes a convex curved surface in both the cross section taken along the one-dot chain line I-I′ and the cross section taken along the one-dot chain line II-II′. 
     By forming the concave surface of the fitting surface  102  and the convex surface of the fitting surface  502  as the curved surfaces corresponding to each other, when the fitting surface  502  contacts the fitting surface  102 , positions of the fitting surface  102  and the fitting surface  502  match, and the fitting surface  102  and the fitting surface  502  are fitted to each other. With this arrangement, the positioning protrusions  512  and  514  can be fitted into the positioning recesses  112  and  114 . At this time, in the present embodiment, the charging stand  100  is moved in the horizontal direction so that the positioning protrusions  512  and  514  and the positioning recesses  112  and  114  are reliably fitted. A mechanism that moves the charging stand  100  in the horizontal direction will be described later in detail. 
     As described above, as illustrated in  FIG. 8 , in a state where the fitting surface  502  is not in contact with the fitting surface  102 , the upper surface of the terminal protection plate  110  is positioned higher than the upper surface of the charging terminal  106 . Thus, the charging terminals  104 ,  106 , and  108  are protected by the terminal protection plate  110 . On the other hand, as illustrated in  FIGS. 9 and 10 , when the robot  500  sits down and the fitting surface  502  and the fitting surface  102  are brought into close contact with each other, the terminal protection plate  110  is lowered by the weight of the robot  500 , so that the charging terminals  104 ,  106 , and  108  appear. With this arrangement, the charging terminals  104 ,  106 , and  108  and the charging terminals  504 ,  506 , and  508  are electrically connected. 
     5. Configurations of Charging Stand and Charging Mat 
     The charging stand  100  can be removed from the charging mat  200 . A user can remove the charging stand  100  from the charging mat  200  by pressing a release button  518  illustrated in  FIG. 1 .  FIG. 11  is a schematic view illustrating the charging stand  100  removed from the charging mat  200 . As illustrated in  FIG. 11 , by removing the charging stand  100  from the charging mat  200 , the charging stand  100  can be used as a portable charging stand. With this arrangement, a user can charge the robot  500  even at a place of visit or the like, for example, by carrying only the charging stand  100  without carrying the charging mat  200 . In the state where the charging stand  100  is removed from the charging mat  200 , power can be supplied by insertion of the AC adapter plug  300  into the charging stand  100 , as illustrated in  FIG. 11 . 
     As illustrated in  FIG. 11 , cushions  116  are provided on an outer edge of the fitting surface  102 . The cushions  116  have a function of preventing a surface of the robot  500  from being scratched or damaged by sliding, and improving slidability of the fitting surface  502  on the fitting surface  102 , in a case where the robot  500  sits down on the charging stand  100 . 
       FIG. 12  is a schematic view illustrating the bottom surface of the charging stand  100 . Rubber feet  120 ,  122 ,  124 , and  126  having a non-slip function are provided on the bottom surface of the charging stand  100 . In a case where the charging stand  100  is used as a portable charging stand, the charging stand  100  is fixed to the floor surface by the rubber feet  120 ,  122 ,  124 , and  126 . 
       FIG. 13  is a schematic view illustrating the charging mat  200  with the charging stand  100  removed. The charging mat  200  is provided with a charging stand installation plate  220 , which enables the charging stand  100  to be attached in a single operation in a case where the charging stand  100  is attached to the charging mat  200 . For this reason, the charging stand installation plate  220  of the charging mat  200  is provided with rail portions  222 ,  224 , and  226  and a lock portion  228 . The lock portion  228  moves in the direction of an arrow A 11  when the release button  518  is pressed, and is biased in the direction opposite to the direction of the arrow A 11  by a spring (not illustrated) in a state where the release button  518  is not pressed. 
     As illustrated in  FIG. 12 , slide protrusions  130 ,  132 , and  134  are provided on the bottom surface of the charging stand  100 . The slide protrusions  130 ,  132 , and  134  of the charging stand  100  move along the rail portions  222 ,  224 , and  226  of the charging mat  200  illustrated in  FIG. 13 , and a lock claw  136  of the charging stand  100  engages with the lock portion  228  of the charging mat  200 , whereby the charging stand  100  is fixed to the charging mat  200 . More specifically, the slide protrusions  134  are hooked to the hook shape at an end of the rail portion  222 , and the lock claw  136  of the charging stand  100  is hooked to the rail portion  226  in this state, whereby the charging stand  100  is fixed to the charging mat  200 . When the lock claw  136  moves in the direction of an arrow A 14  in  FIG. 12 , the lock claw  136  and the rail portion  226  are disengaged, and the charging stand  100  can be removed from the charging mat  200 . When the charging stand  100  is fixed to the charging mat  200 , a charging mat connection terminal  230  illustrated in  FIG. 12  and a charging stand connection terminal  138  illustrated in  FIG. 13  contact each other. With this arrangement, the charging stand  100  and the charging mat  200  are electrically connected. 
       FIG. 14  is a schematic view for describing horizontal movement of the charging stand  100 . Basically, the robot  500  can approach the charging stand  100  from an access direction A 1  or an access direction A 2  illustrated in  FIG. 14 , and can be connected to the charging stand  100 . 
     As illustrated in  FIG. 14 , the charging stand  100  can move on the charging mat  200  in a transverse direction A 3  or a longitudinal direction A 4  (the same direction as the access directions A 1  and A 2 ) with respect to the access directions A 1  and A 2 , and can also rotate in rotation directions A 5  and A 6 . Furthermore, the charging stand  100  is capable of movement in which movement in the transverse direction A 3 , the longitudinal direction A 4 , and the rotation directions A 5  and A 6  are combined. 
       FIG. 15  is a schematic view illustrating a mechanism of a movable part that enables movement in the transverse direction A 3 , the longitudinal direction A 4 , and the rotation directions A 5  and A 6  illustrated in  FIG. 14 , and schematically illustrates the charging mat  200  as viewed from the back surface. As illustrated in  FIG. 15 , the charging mat  200  is provided with a slider  232 , springs (tensile springs)  234 ,  236 ,  238 , and  240 , a harness  242 , and a connection substrate  244 . The slider  232  is fastened to the charging stand installation plate  220  illustrated in  FIG. 13 . The slider  232  is supported by the four springs  234 ,  236 ,  238 , and  240  and can be freely moved by expansion and contraction of the springs  234 ,  236 ,  238 , and  240 . This arrangement enables movement in the transverse direction A 3 , the longitudinal direction A 4 , and the rotation directions A 5  and A 6  illustrated in  FIG. 14 . 
     Power is supplied to the robot  500  by connecting the AC adapter plug  300  illustrated in  FIG. 15  from an AC adapter to the connection substrate  244 . The connection substrate  244  and the charging stand connection terminal  138  illustrated in  FIG. 13  are electrically connected via the harness  242 , and when the charging stand  100  is mounted on the charging mat  200 , the charging stand connection terminal  138  and the charging mat connection terminal  230  illustrated in  FIG. 12  are electrically connected. Thus, power is supplied to the charging stand  100  via the connection substrate  244 , the harness  242 , the charging stand connection terminal  138 , and the charging mat connection terminal  230 . The charging terminals  104 ,  106 , and  108  illustrated in  FIG. 1  are electrically connected to the charging terminals  504 ,  506 , and  508  on the robot side illustrated in  FIG. 5 , whereby the power supplied to the charging stand  100  is supplied to the robot  500 . 
     The charging station  1000  has a degree of freedom of the charging stand  100  in the transverse direction A 3 , the longitudinal direction A 4 , and the rotation directions A 5  and A 6  illustrated in  FIG. 14 . Thus, in a case where the robot  500  accesses the charging stand  100 , the charging stand  100  can correct an approach angle and a positional deviation at the time of sitting. When the fitting surface  502  of the robot  500  and the fitting surface  102  of the charging stand  100  are fit, the charging stand  100  itself moves, so that it is possible to passively align the charging stand  100  with the robot  500 . 
     More specifically, when the fitting surface  502  and the fitting surface  102  are fit, in a case where positions of the positioning protrusions  512  and  514  do not match positions of the positioning recesses  112  and  114 , the positioning protrusions  512  and  514  are pressed onto the fitting surface  102  by the weight of the robot  500 . At this time, since the positioning protrusions  512  and  514  are pressed onto a slope of the concave surface of the fitting surface  102 , the charging stand  100  that received a reaction force from the slope moves in the horizontal direction by expansion and contraction of the springs  234 ,  236 ,  238 , and  240 . With this arrangement, in accordance with the concave curved surface of the fitting surface  102 , the positioning protrusions  512  and  514  are fitted into the positioning recesses  112  and  114  at the lowest positions of the concave curved surface. 
     Furthermore, even in a case where the robot  500  fails to have a good positional relationship with the charging stand  100  when the robot  500  approaches the charging stand  100  and paws of the robot  500  interfere with the charging stand  100 , the charging stand  100  can retreat since the charging stand  100  has the degree of freedom in the transverse direction A 3 , the longitudinal direction A 4 , and the rotation directions A 5  and A 6  illustrated in  FIG. 14 , and thus a sitting motion can be performed without hindering movement of the robot  500 . 
     Examples of another function of the charging mat  200  include a function of preventing interference between a cord for supplying power to the charging stand  100  and the robot  500 . In a case where the robot  500  accesses the charging stand  100 , the cord for supplying power to the charging stand  100  is covered with the charging mat  200 . With this arrangement, the cord for supplying power and the like does not hinder the robot  500  from accessing the charging stand  100 . 
     The robot  500  recognizes the charging station  1000  on the basis of the color and the shape of the charging station  1000 . In addition, the robot  500  recognizes an approach direction and a distance from the charging stand  100  on the basis of the shape of the charging stand  100 . For this reason, the robot  500  includes a camera  520  for recognizing the color, the shape, and the like of the charging stand  100  and the charging mat  200 . The robot  500  can recognize the color and the shape of the charging station  1000  on the basis of an image captured by the camera  520 , and can control a walking direction, a posture, and the like on the basis of a recognition result. 
     In a case where the robot  500  performs self-charging, the robot  500  recognizes the charging station  1000  and approaches the charging station  1000 . When the robot  500  approaches the charging station  1000 , the robot  500  recognizes the shape of the charging stand  100 , goes up a slope  245  illustrated in  FIG. 8  from the longer direction of the charging stand  100  (the direction of the arrow A 1  or the arrow A 2  illustrated in  FIG. 14 ), and rides on the charging mat  200 , so as to take the “dive” or “sitting” posture described with reference to  FIGS. 4A and 4B . 
     At this time, by providing the charging mat  200 , conditions in a case where the robot  500  accesses the charging stand  100 , for example, a state of the floor surface, the color of the floor surface, exclusion of obstacles, and the like can be made constant. In other words, the state of the floor surface around the charging stand  100  and the color of the floor surface are uniformed by a state of the upper surface of the charging mat  200  and the color of the charging mat  200 . In addition, by providing the charging mat  200 , obstacles are inevitably excluded from around the charging stand  100 . 
     Therefore, according to the charging station  1000  of the present embodiment, conditions in a case where the robot  500  accesses the charging stand  100  can be kept constant regardless of varieties of the color and a state of the floor surface on which the robot  500  walks, so that self-charging can be reliably performed. 
     In a case where the robot  500  fails to sit down on the charging stand  100 , the robot  500  can finely adjust its position on the charging stand  100  by activating a correction motion. In the correction motion, the robot  500  performs an operation in which the robot  500  moves minutely to the front, back, left, and right, or vibrates. By the activation of the correction motion, the fitting surface  502  on the bottom of the robot slides along the fitting surface  102  of the charging stand  100 , and the positioning protrusions  512  and  514  are fitted into the positioning recesses  112  and  114  illustrated in  FIG. 1 , whereby the charging stand  100  moves to a desired position. Thus, it is possible to perform fine adjustment for correcting positional deviation. 
       FIG. 16  is a schematic view illustrating an example in which a groove  246  having the shape similar to the shape of the bottom of a paw  510  of the robot  500  is provided along an edge of the charging mat  200 . In addition,  FIG. 17  is a schematic view illustrating a cross section of the charging station  1000  illustrated in  FIG. 16  taken along a line similar to the one-dot chain line I-I′ in  FIG. 7 . By providing the groove  246 , it is possible to prevent the paw  510  of the robot  500  from sliding off the charging mat  200 . Furthermore, since the groove  246  having the same shape as the paw  510  is provided along the edge of the charging mat  200 , both front paws of the robot  500  fit into the groove  246 , and the robot  500  can be automatically directed toward the charging stand  100 . 
     The shape of the charging stand  100  may be circular when viewed from above.  FIG. 18A  is a plan view of the charging stand  100  as viewed from above, and is a schematic view illustrating the charging stand  100  having a circular planar shape. In addition,  FIG. 18B  is a schematic view illustrating a cross section taken along a one-dot chain line III-III′ in  FIG. 18A . 
     As illustrated in  FIG. 18A , a charging terminal  140  is provided at the center of the charging stand  100 . In addition, around the charging terminal  140 , a ring-shaped charging terminal  142  is provided on a concentric circle centering on the charging terminal  140 . In addition, a ring-shaped positioning recess  144  is provided further outside the charging terminal  142 . The positioning recess  144  is arranged concentrically with the charging terminal  142 . 
       FIGS. 19A and 19B  are schematic views illustrating the fitting surface  502  of the robot  500  connected to the charging stand  100  illustrated in  FIGS. 18A and 18B .  FIG. 19A  is a plan view illustrating the fitting surface  502 . In addition,  FIG. 19B  is a schematic view illustrating a cross section taken along a one-dot chain line IV-IV′ in  FIG. 19A . 
     As illustrated in  FIG. 19A , a charging terminal  540  is provided on the fitting surface  502  of the robot  500 . In addition, around the charging terminal  540 , a ring-shaped charging terminal  542  is provided on a concentric circle centering on the charging terminal  540 . In addition, positioning protrusions  544  are provided further outside the charging terminal  542 . 
     In  FIG. 19A , a circle C passing through the three positioning protrusions  544  is arranged concentrically with the charging terminal  542 . In addition, the diameter of the circle C is the same as the diameter of the ring-shaped positioning recess  144  illustrated in  FIG. 18A . Thus, when the robot  500  sits down on the charging station  1000  and the fitting surface  502  is brought into close contact with the fitting surface  102 , the three positioning protrusions  544  are fitted into the ring-shaped positioning recess  144 . Then, when the positioning protrusions  544  are fitted into the ring-shaped positioning recess  144 , the charging terminal  140  contacts the charging terminal  540 , and the charging terminal  142  contacts the charging terminal  542 . With this arrangement, the robot  500  and the charging stand  100  are electrically connected, so that the robot  500  can be charged. 
     As described above, the three positioning protrusions  544  on the robot  500  side enter the positioning recess  144  on the charging station  1000  side, and the positions of the charging station  1000  and the robot  500  are determined. The charging terminals are concentrically formed on both the charging station  1000  side and the robot  500  side, and the robot  500  can access the charging stand  100  from any direction within 360°. Note that, in the case of the charging stand  100  illustrated in  FIG. 18A , it is preferable that the planar shape of charging mat  200  be also circular. 
     As described above, according to the present embodiment, when the robot  500  sits down, the position can be corrected on the charging stand  100  side. Thus, fine adjustment of the position on the robot  500  side is not required, and the robot  500  can sit down on the charging stand  100  for charging in a short time. 
     In addition, since the charging station  1000  includes the charging stand  100  and the charging mat  200 , these can be combined and separated depending on a situation. At this time, since the robot  500  can be charged only by the charging stand  100 , the charging stand  100  can be used as a portable charging stand. 
     By providing the charging mat  200 , the power supply cord for supplying power can be covered, so that the power supply cord does not hinder the robot  500  in a case where the robot  500  accesses the charging stand  100 . In addition, by providing the charging mat  200 , conditions in the case where the robot  500  accesses the charging stand can be made constant. 
     In addition, even if the robot  500  interferes with the charging stand  100  during access to the charging stand  100 , the charging stand  100  can move to retreat so as not to hinder the robot  500  from accessing the charging station  1000 . 
     In addition, by providing the groove having the same shape as the shape of the bottom of the paw of the robot  500  along the edge of the charging mat  200 , it is possible to prevent the paw of the robot from sliding off the mat. In addition, by providing the groove  246  having the same shape as the paw of the robot  500  along the edge of the charging mat  200 , both the front paws of the robot  500  fit into the groove  246 , and the robot  500  can be automatically directed toward the charging stand  100 . 
     The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but a technical scope of the present disclosure is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field of the present disclosure can conceive of various changes or modifications within the scope of the technical idea described in the claims, and as a matter of course, it is understood that the changes or the modifications also belongs to the technical scope of the present disclosure. 
     In addition, the effects described in the present specification are merely illustrative or exemplary and not limiting. That is, the technology according to the present disclosure can exhibit other effects that are apparent to those skilled in the art from the description of the present specification in addition to or instead of the above effects. 
     Note that the following configurations also belong to the technical scope of the present disclosure. 
     (1) A charging device including: 
     a charging stand having a charging terminal to be connected to a device to be charged and an engaging portion that performs positioning with the device to be charged; and 
     a support member that supports the charging stand movably in the horizontal direction. 
     (2) The charging device according to (1), further including a fitting surface provided with the charging terminal and the engaging portion, in which the fitting surface is fitted with a surface to be fitted provided on the device to be charged. 
     (3) The charging device according to (2), in which the fitting surface faces upward, and when the surface to be fitted of the device to be charged is lowered, the fitting surface and the surface to be fitted are fitted. 
     (4) The charging device according to (2), in which the fitting surface forms a concave surface facing upward, and the surface to be fitted forms a convex surface facing downward. 
     (5) The charging device according to (2), in which the engaging portion is a recess formed on the fitting surface, and a protrusion provided on the surface to be fitted is fitted into the engaging portion. 
     (6) The charging device according to (5), in which the charging terminal and a terminal of the device to be charged are electrically connected by fitting the engaging portion into the protrusion. 
     (7) The charging device according to (2), in which the engaging portion is provided at a lowermost portion of the fitting surface. 
     (8) The charging device according to any one of (1) to (7), in which the charging stand is attached to and detached from the support member. 
     (9) The charging device according to any one of (1) to (8), in which the support member covers a wiring connected to the charging stand. 
     (10) The charging device according to any one of (1) to (9), further including elastic members that support the charging stand movably in the horizontal direction with respect to the support member. 
     (11) The charging device according to (10), in which the elastic members are springs that pull the charging stand from four directions. 
     (12) The charging device according to any one of (1) to (11), in which the charging stand has a planar shape extending in a predetermined direction, and the device to be charged accesses the charging stand from the predetermined direction. 
     (13) The charging device according to any one of (1) to (12), in which 
     the support member is configured as a charging mat having a larger planar shape than a planar shape of the charging stand, and 
     the charging stand is provided to protrude from the upper surface of the charging mat. 
     (14) The charging device according to any one of (1) to (13), in which the device to be charged is a walking robot. 
     (15) The charging device according to (14), in which a groove corresponding to a shape of a paw of the robot is provided around the support member. 
     (16) The charging device according to (14), in which 
     the robot includes a camera that captures a surrounding image, and 
     the charging device is recognized by the robot on the basis of a shape and a color obtained from the image captured by the camera. 
     (17) The charging device according to (16), in which an approach direction of the robot to the charging stand is determined on the basis of a shape of the charging stand. 
     (18) The charging device according to (5), in which the engaging portion and the protrusion are fitted in accordance with movement of the device to be charged. 
     (19) A charging method in a charging device including 
     a charging stand having a charging terminal to be connected to a device to be charged and an engaging portion that performs positioning with the device to be charged, and 
     a support member that supports the charging stand movably in the horizontal direction, 
     the charging method including: 
     positioning the device to be charged on the charging stand; and 
     electrically connecting the charging terminal and a terminal of the device to be charged by lowering the device to be charged. 
     (20) A charging system including: 
     a movable device to be charged; and 
     a charging device including a charging stand having a charging terminal to be connected to a device to be charged and an engaging portion that performs positioning with the device to be charged, and a support member that supports the charging stand movably in the horizontal direction. 
     REFERENCE SIGNS LIST 
     
         
           100  Charging stand 
           102 ,  502  Fitting surface 
           104 ,  106 ,  108 ,  504 ,  506 ,  508  Charging terminal 
           112 ,  114  Positioning recess 
           200  Charging mat 
           234 ,  236 ,  238 ,  240  Spring 
           500  Robot 
           510  Paw 
           520  Camera 
           512 ,  514  Positioning protrusion