Patent Publication Number: US-2022229443-A1

Title: Autonomous mobile system, autonomous mobile method, and autonomous mobile program

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to Japanese Patent Application No. 2021-007933 filed on Jan. 21, 2021, incorporated herein by reference in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an autonomous mobile system, an autonomous mobile method, and an autonomous mobile program. 
     2. Description of Related Art 
     Development of autonomous mobile devices that autonomously move within a predetermined building or facility is in progress. Such an autonomous mobile device having a loading platform can serve as an autonomous transportation device that automatically delivers a package. The autonomous transportation device can, for example, deliver the package loaded at the departure point to the destination by autonomously moving from the departure point to the destination. 
     For example, Japanese Unexamined Patent Application Publication No. 2007-249735 (JP 2007-249735 A) and the like describes that, when an autonomous mobile robot that autonomously travels in a predetermined area is brought to in an error state and loses its own position and direction, a radio frequency identification (RFID) tag installed in the traveling area is read by a reader or a landmark is imaged with a camera mounted on the robot to restore the grasp of its own position. 
     SUMMARY 
     In order to travel an autonomous mobile robot such as the one described in JP 2007-249735 A and the like, targets such as RFID tags and landmarks need to be installed in advance in the facility in case the robot is brought to an error state and loses its position information. Therefore, there is a possibility that an autonomous mobile robot such as the one described in JP 2007-249735 A and the like cannot be restored when an error occurs at a position where the RFID tag and the like cannot be recognized and the position information is lost. 
     The present disclosure has been made to solve such an issue, and provides an autonomous mobile system, an autonomous mobile method, and an autonomous mobile program capable of restoring easily even when the position information is lost. 
     An autonomous mobile system according to the present embodiment is an autonomous mobile system that autonomously moves in a facility using position information. In a case where the position information is lost due to an activation of a forced stop switch for stopping autonomous movement of the autonomous mobile system, when the activation of the forced stop switch is released and the autonomous movement is restored, the autonomous mobile system acquires the position information from a facility camera in the facility that has captured an image of the autonomous mobile system or from another autonomous mobile system that has detected the autonomous mobile system. With such a configuration, the autonomous mobile system can be easily restored even when losing the position information. 
     In the above autonomous mobile system, when the forced stop switch is activated, transmission of a heartbeat signal that is periodically transmitted to a server device communicably connected to the autonomous mobile system may be stopped, and when the activation of the forced stop switch is released and the autonomous movement is restored, the autonomous mobile system may resume the transmission of the heartbeat signal to acquire the position information via the server device. With such a configuration, the server device can easily detect the activation of the forced stop switch. 
     In the above autonomous mobile system, the autonomous mobile system may acquire direction information indicating a direction of the autonomous mobile system together with the position information. With such a configuration, the autonomous mobile system can be easily restored even when losing the position information. 
     In the above autonomous mobile system, when the forced stop switch is activated, the autonomous mobile system may notify an administrator of the autonomous mobile system of the activation of the forced stop switch. With such a configuration, the administrator can easily detect the forced stop. 
     In the above autonomous mobile system, the autonomous mobile system that has acquired the position information may move to a base point fixed in the facility, and may acquire base point information that serves as a reference for the position information by positioning at the base point. With such a configuration, the accuracy of the position information can be improved. 
     An autonomous mobile system according to the present embodiment includes: an autonomous mobile device that autonomously moves in a facility using position information; a facility camera that is fixed in the facility and captures an image of a periphery of the facility camera to generate image data; and a server device that transmits and receives traveling information to and from the autonomous mobile device, and acquires the image data from the facility camera. In a case where the autonomous mobile device has lost the position information due to an activation of a forced stop switch for stopping autonomous movement of the autonomous mobile device, when the activation of the forced stop switch is released and the autonomous movement is restored, the server device acquires the position information of the autonomous mobile device from the facility camera that has captured an image of the autonomous mobile device or from another autonomous mobile device that has detected the autonomous mobile device, and transmits the acquired position information to the autonomous mobile device. The autonomous mobile device acquires the position information from the server device. With such a configuration, the autonomous mobile device can be easily restored even when losing the position information. 
     In the above autonomous mobile system, the autonomous mobile device may stop transmission of a heartbeat signal that is periodically transmitted to the server device, when the forced stop switch is activated, and may resume the transmission of the heartbeat signal to acquire the position information via the server device, when the activation of the forced stop switch is released and the autonomous movement is restored. With such a configuration, the server device can easily detect the activation of the forced stop switch. 
     In the above autonomous mobile system, the autonomous mobile device may acquire direction information indicating a direction of the autonomous mobile device together with the position information. With such a configuration, the autonomous mobile device can be easily restored even when losing the position information. 
     In the above autonomous mobile system, the autonomous mobile device or the server device may notify an administrator of the autonomous mobile system of the activation of the forced stop switch, when the forced stop switch is activated. With such a configuration, the administrator can easily detect the forced stop. 
     In the above autonomous mobile system, the autonomous mobile device that has acquired the position information may move to a base point fixed in the facility, and may acquire base point information that serves as a reference for the position information by positioning at the base point. With such a configuration, the accuracy of the position information can be improved. 
     An autonomous mobile method according to the present embodiment is an autonomous mobile method for an autonomous mobile device that autonomously moves in a facility using position information. The autonomous mobile method includes causing the autonomous mobile device to acquire the position information from a facility camera in the facility that has captured an image of the autonomous mobile device or from another autonomous mobile device that has detected the autonomous mobile device, in a case where the autonomous mobile device has lost the position information due to an activation of a forced stop switch for stopping autonomous movement of the autonomous mobile device, and when the activation of the forced stop switch is released and the autonomous movement is restored. With such a configuration, the autonomous mobile device can be easily restored even when losing the position information. 
     An autonomous mobile program according to the present embodiment is an autonomous mobile program for an autonomous mobile device that autonomously moves in a facility using position information. The autonomous mobile program causes a computer to execute acquisition of the position information by the autonomous mobile device from a facility camera in the facility that has captured an image of the autonomous mobile device or from another autonomous mobile device that has detected the autonomous mobile device, in a case where the autonomous mobile device has lost the position information due to an activation of a forced stop switch for stopping autonomous movement of the autonomous mobile device, and when the activation of the forced stop switch is released and the autonomous movement is restored. With such a configuration, the autonomous mobile device can be easily restored even when losing the position information. 
     The present embodiment can provide an autonomous mobile system, an autonomous mobile method, and an autonomous mobile program capable of restoring easily even when the position information is lost. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the disclosure will be described below with reference to the accompanying drawings, in which like signs denote like elements, and wherein: 
         FIG. 1  is a schematic view illustrating a mobile robot according to a first embodiment; 
         FIG. 2  is a perspective view illustrating the mobile robot according to the first embodiment; 
         FIG. 3  is a block diagram illustrating the mobile robot according to the first embodiment; 
         FIG. 4  is a flowchart illustrating an operation of acquiring position information when the mobile robot according to the first embodiment loses the position information due to the activation of a forced stop switch for stopping autonomous movement; 
         FIG. 5  is a block diagram illustrating a server device according to a second embodiment; and 
         FIG. 6  is a sequence diagram illustrating the operation of an autonomous mobile system according to the second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, the present disclosure will be described through embodiments of the disclosure, but the disclosures in the claims are not limited to the following embodiments. Moreover, not all of the configurations described in the embodiments are indispensable as means for solving the problem. For the sake of clarity, the following description and drawings have been omitted and simplified as appropriate. In each drawing, the same elements are designated by the same reference signs, and duplicate descriptions are omitted as necessary. 
     First Embodiment 
     An autonomous mobile system according to a first embodiment will be described. In the present embodiment, the autonomous mobile system may be replaced with an autonomous mobile device, or the autonomous mobile device may be replaced with the autonomous mobile system. Further, the autonomous mobile system according to the present embodiment may include the autonomous mobile device. The autonomous mobile device autonomously moves in a predetermined facility. The autonomous mobile device may be, for example, a mobile robot that autonomously moves, or a transportation robot that autonomously moves to transport an object. Hereinafter, the mobile robot will be described as an example of the autonomous mobile device. The mobile robot will be described separately in “Structure of Mobile Robot” and “Operation of Mobile Robot”. 
     Structure of Mobile Robot 
       FIG. 1  is a schematic view illustrating the mobile robot according to the first embodiment. As shown in  FIG. 1 , a mobile robot  100  is an example of the autonomous mobile device that autonomously moves in a predetermined facility  900 . The predetermined facility  900  is, for example, a hospital. The predetermined facility  900  is not limited to a hospital, and may be a hotel, a shopping mall, or the like as long as the mobile robot  100  can move autonomously in the predetermined facility  900 . 
     The mobile robot  100  autonomously moves on a floor surface  910  in the facility  900  using position information in the facility  900 . The position information includes, for example, the current position of the mobile robot  100 . The position information may include, for example, the direction of the mobile robot  100 , the position of an obstacle around the mobile robot  100 , and the like. 
     A facility camera  400  is fixed in the facility  900 . For example, the facility camera  400  is fixed to a ceiling  920  of the facility  900 , and captures images of the periphery of the facility camera  400  to generate image data. The facility camera  400  captures images of, for example, an aisle, a corner, a passerby, the mobile robot  100 , and the like. A plurality of the facility cameras  400  may be provided in the facility  900 . 
     The mobile robot  100  and the facility camera  400  may be connected to each other so as to be able to communicate with each other via information transmission means such as wireless communication. The mobile robot  100  and the facility camera  400  may be connected to each other so as to be able to directly communicate with each other, or may be connected to each other so as to be able to communicate with each other via an access point  500  and a server device  300 . Therefore, the mobile robot  100  may acquire the image data directly from the facility camera  400 , or may acquire the image data via the access point  500  and the server device  300 . 
     The access point  500  is, for example, a wireless local area network (LAN) access point. The access point  500  is fixed in the facility  900  and acquires position information, traveling information, and the like from the mobile robot  100  located in the periphery of the access point  500 . A plurality of the access points  500  may be provided in the facility  900 . 
     A plurality of the mobile robots  100  may autonomously move in the facility  900 . When the mobile robots  100  autonomously move, the mobile robots  100  may be connected to each other so as to be able to communicate with each other via information transmission means such as wireless communication. The mobile robots  100  may be connected to each other so as to be able to directly communicate with each other, or may be connected to each other so as to be able to communicate with each other via the access point  500  and the server device  300 . Here, when distinguishing another mobile robot from a specific mobile robot  100 , the other mobile robot is referred to as another mobile robot  100 A or simply a mobile robot  100 A to distinguish the other mobile robot from the mobile robot  100 . 
     A base point  600  may be fixed in the facility  900 . The base point  600  is, for example, a mark provided on the ceiling  920 . The base point  600  is not limited to the mark provided on the ceiling  920 . The base point  600  may be fixed to the floor surface  910 , the wall surface, or the like, instead of the ceiling  920 . Further, the base point  600  is not limited to the mark. The base point  600  may be a code such as a QR code (registered trademark) or a bar code, a light emitting point, a radio frequency identification (RFID) tag, a battery charger built in the mobile robot  100 , or the like. A plurality of the base points  600  may be provided in the facility  900 . 
     By positioning at the base point  600  fixed in the facility  900 , the mobile robot  100  acquires base point information that serves as a reference for the position in the facility  900 . For example, the base point information is acquired by stopping at a position where the base point information can be acquired, such as directly below or directly above the base point  600 . The base point information acquired from the base point  600  serves as a reference for the position information in the facility  900 , and is information for improving the accuracy of the position information. For example, the mobile robot  100  calculates the position information by adding distance information detected by a sensor group of the mobile robot  100  to the base point information acquired from the base point  600 . Specifically, the mobile robot  100  updates the position information by adding the mileage and the traveling direction from the base point  600 . As a result, the mobile robot  100  can improve the accuracy of the position information. 
       FIG. 2  is a perspective view illustrating the mobile robot  100  according to the first embodiment.  FIG. 3  is a block diagram illustrating the mobile robot  100  according to the first embodiment. As shown in  FIGS. 2 and 3 , the mobile robot  100  includes a drive unit  110 , a housing unit  120 , a communication unit  130 , an operation reception unit  140 , a display unit  150 , a sensor group  160 , a forced stop switch  141 , a start switch  142 , an identification (ID) sensor  170 , a control unit  180 , an arithmetic unit  185 , and a storage unit  190 . 
     As shown in  FIG. 2 , the mobile robot  100  is a mobile body that moves on the floor surface  910  that is a moving surface. Here, for convenience of explanation of the mobile robot  100 , the XYZ orthogonal coordinate axis system is used. The floor surface  910  is the XY-plane, and the upper side is the +Z axis direction. 
     The drive unit  110  functions as means for moving the mobile robot  100 . The drive unit  110  may include two drive wheels  111  that are in contact with the floor surface  910  and are rotatable independently from each other about one rotation axis that extends in a direction (right-left direction or Y-axis direction in the drawing) perpendicular to a straight direction (front-rear direction or X-axis direction in the drawing), and casters  112  in contact with the floor surface  910 . The mobile robot  100  moves forward or rearward in a manner such that the drive wheels  111  disposed on the right and left sides are driven at the same rotation speed, and makes a turn by generating a difference in the rotation speed or rotation direction between the right and left drive wheels  111 . The drive unit  110  drives the drive wheels  111  in accordance with commands from the control unit  180 . 
     The housing unit  120  is disposed above the drive unit  110  of the mobile robot  100 . The housing unit  120  may have a storage chamber door  121 . When the storage chamber door  121  is opened, a storage chamber for storing a predetermined object is provided inside the housing unit  120 . That is, the mobile robot  100  can also be a transportation robot that transports a predetermined object. The housing unit  120  may open and close the storage chamber door  121  in accordance with a command from the control unit  180 . 
     As shown in  FIG. 3 , the communication unit  130  is an interface that is communicably connected to the outside. The communication unit  130  includes, for example, an antenna and a circuit that modulates or demodulates a signal transmitted through the antenna. The communication unit  130  receives the image data directly from the facility camera  400  or via the access point  500  and the server device  300 . 
     Further, the communication unit  130  may receive information related to the destination, the position information, the traveling information and the like from the server device  300 . Further, the communication unit  130  may transmit information related to the state of the mobile robot  100 , the position information, the traveling information, and the like to the server device  300 . Further, the communication unit  130  may transmit and receive the position information and the image data to and from the other mobile robot  100 A directly or via the access point  500  and the server device  300 . 
     The communication unit  130  may periodically transmit a heartbeat signal to the server device  300 . The heartbeat signal may include log data indicating the state of the mobile robot  100  in the chronological order. Further, the heartbeat signal may include the ID of the mobile robot  100 . 
     The communication unit  130  connects to the control unit  180 , outputs, to the control unit  180 , a signal including information transmitted from the facility camera  400  and the server device  300 , and transmits, to the server device  300 , the signal including the information output from the control unit  180 . 
     The operation reception unit  140  receives an input operation from the user and transmits an operation signal to the control unit  180 . As means for receiving an input operation from the user, the operation reception unit  140  may include, for example, an operation button, a touch panel superimposed on the display unit  150 , or the like. The user operates the input operation means described above to turn on and off the power supply, open and close the storage chamber door  121 , and the like. 
     The display unit  150  is provided, for example, so as to project from the upper surface of the housing unit  120 . The display unit  150  is, for example, a display unit including a rectangular liquid crystal panel. The display unit  150  appropriately displays information in accordance with the command from the control unit  180 . A touch panel that receives operations from the user may be superimposed on the display unit  150 . 
     The sensor group  160  includes sensors that acquire data necessary for the mobile robot  100  to move autonomously. The sensor group  160  includes, for example, a robot camera  161  and a distance sensor  162 . The sensor group  160  may include sensors other than the robot camera  161  and the distance sensor  162 . For example, the sensor group  160  may include an encoder provided in the drive unit  110 . 
     The robot camera  161  is disposed in an upper portion of the housing unit  120  and below the display unit  150 , for example. In the robot camera  161 , two camera units having the same angle of view may be disposed horizontally separated from each other. With this configuration, the images captured by each camera unit are output to the control unit  180  as the image data. Further, when the base point  600  is a mark provided on the ceiling  920 , the robot camera  161  may capture an image of the mark on the ceiling  920 . 
     The distance sensor  162  is disposed, for example, in the lower portion of the housing unit  120 . The distance sensor  162  may be disposed in the lower portion of each of a surface on the +X-axis direction side, a surface on the −X-axis direction side, a surface on the +Y-axis direction side, and a surface on the −Y-axis direction side of the housing unit  120 . The distance sensor  162  measures the distance between an object around the mobile robot  100  and the mobile robot  100 . The control unit  180  recognizes the obstacle around the mobile robot  100  by analyzing the image data output by the robot camera  161  and the detection signals output by the distance sensor  162 , and measures the distance between the mobile robot  100  and the obstacle. 
     The mobile robot  100  may acquire the position information by any of the sensors in the sensor group  160 . For example, the mobile robot  100  captures an image of the base point  600  with the robot camera  161  to acquire the base point information, and calculates the position information from the base point information. The mobile robot  100  may acquire the position information from the server device  300 , the facility camera  400 , and the other mobile robot  100 A via the communication unit  130 . 
     The ID sensor  170  is provided, for example, near the display unit  150 . The ID sensor  170  identifies the ID of the user who operates the mobile robot  100 , and detects a unique identifier included in the ID card owned by each user. The ID sensor  170  includes, for example, an antenna for reading information on a wireless tag. The user brings the ID card close to the ID sensor  170  such that the mobile robot  100  is caused to recognize the ID of the user who is the operator. 
     The forced stop switch  141  and the start switch  142  may be respectively provided as a forced stop button and a restart button in the vicinity of the operation reception unit  140 , or may be superimposed on the touch panel of the display unit  150 , for example. 
     The forced stop switch  141  stops the autonomous movement of the mobile robot  100 . That is, the forced stop switch  141  stops the traveling of the mobile robot  100 . The forced stop switch  141  may stop other functions of the mobile robot  100 . For example, the forced stop switch  141  may stop the function of the drive unit  110  as moving means, or may stop the function of the communication unit  130  as communication means. Further, the forced stop switch  141  may stop the sensor function of the sensor group  160 . The forced stop switch  141  may stop at least one function of the functions of the mobile robot  100 , or may stop all the functions of the mobile robot  100 . When the forced stop switch  141  is activated, the transmission of the heartbeat signal that is periodically transmitted to the server device  300  communicably connected to the mobile robot  100  may be stopped. As a result, the server device  300  can detect that the mobile robot  100  has stopped the autonomous movement. 
     The start switch  142  releases the activation of the forced stop switch  141  and restores the autonomous movement of the mobile robot  100 . The start switch  142  may activate at least one of the predetermined functions of the mobile robot  100  that have been stopped. For example, when the forced stop switch  141  stops the function of the drive unit  110  as the moving means, the start switch  142  activates the function of the drive unit  110  as the moving means. When the forced stop switch  141  stops the function of the communication unit  130  as the communication means, the start switch  142  may activate the function of the communication unit  130  as the communication means. When the forced stop switch  141  stops the sensor function of the sensor group  160 , the start switch  142  may activate the sensor function of the sensor group  160 . When the activation of the forced stop switch  141  is released and the autonomous movement is restored due to the activation of the start switch  142 , the transmission of the heartbeat signal may be resumed. As a result, the server device  300  can detect that the mobile robot  100  has restored the autonomous movement. 
     The control unit  180  is an information processing device including an arithmetic device such as a central processing unit (CPU). The control unit  180  includes hardware provided in the control unit  180  and a program stored in the hardware. That is, processes executed by the control unit  180  are realized by either hardware or software. 
     The control unit  180  acquires various types of information from each configuration and issues a command to each configuration in accordance with the acquired information. For example, the control unit  180  detects the distance between the mobile robot  100  and the surrounding object from the image data acquired from the robot camera  161  and the information on the object around the mobile robot  100  acquired from the distance sensor  162 . Then, the control unit  180  calculates a route to the destination from the detected distance, and commands the drive unit  110  to move along the route in accordance with the calculated route. When executing such a process, the control unit  180  refers to information related to a floor map stored in the storage unit  190 . 
     The control unit  180  causes the drive unit  110  to move to the base point  600  fixed in the facility  900 . Then, the sensor group  160  or the communication unit  130  is made to acquire the base point information. 
     Further, when restoring the autonomous movement of the mobile robot  100 , the control unit  180  causes the communication unit  130  to acquire the position information from the facility camera  400  or the other mobile robot  100 A. For example, the communication unit  130  acquires the image data from the facility camera  400  that has captured the image of the mobile robot  100 . The communication unit  130  may acquire the image data from the other mobile robot  100 A that has captured the image of the mobile robot  100 . The image data includes the position information of the mobile robot  100 . Further, the communication unit  130  may acquire the position information of the other mobile robot  100 A from the other mobile robot  100 A. The position information of the other mobile robot  100 A includes the position information from the point of view of the mobile robot  100 . The control unit  180  causes the arithmetic unit  185  to calculate the position information related to the mobile robot  100  from the position information acquired from the other mobile robot  100 A. 
     Specifically, the arithmetic unit  185  can calculate the position information in the facility  900  from the position of the mobile robot  100  whose captured image is included in the acquired image data. Further, the arithmetic unit  185  can calculate the position information by adding the distance information from the other mobile robot  100 A to the position information of the other mobile robot  100 A. 
     The control unit  180  may acquire information indicating the direction of the mobile robot  100  together with the position information. Here, the forward direction of the mobile robot  100  is referred to as the direction of the mobile robot  100 , and the information indicating the direction of the mobile robot  100  is referred to as direction information. 
     When the forced stop switch  141  is activated, the control unit  180  causes the communication unit  130  to stop the transmission of the heartbeat signal that is periodically transmitted to the server device  300 . When the activation of the forced stop switch  141  is released and the autonomous movement is restored, the control unit  180  causes the communication unit  130  to resume the transmission of the heartbeat signal. As a result, the position information is acquired via the server device  300 . 
     When the forced stop switch  141  is activated, the control unit  180  may cause the communication unit  130  to notify the administrator of the mobile robot  100  of the activation of the forced stop switch  141 . 
     The storage unit  190  includes a non-volatile memory such as a flash memory and a solid state drive (SSD). The storage unit  190  stores the position information. The storage unit  190  may update the position information at any time, for example, every time the mobile robot  100  moves. The storage unit  190  stores the floor map of the facility used by the mobile robot  100  for the autonomous movement. The storage unit  190  is connected to the control unit  180 , and outputs stored information to the control unit  180  in response to a request from the control unit  180 . 
     As shown in  FIG. 2 , the mobile robot  100  has the +X-axis direction side on which the robot camera  161  is installed as the front. That is, during normal movement, the traveling direction is the +X-axis direction as shown by the arrow. 
     Various ideas can be adopted for how to define the front of the mobile robot  100 . For example, the front can be defined based on how the sensor group  160  for recognizing the surrounding environment is disposed. Specifically, the +X-axis direction side of the housing unit  120  on which the sensor having high recognition ability is disposed or many sensors are disposed can be set as the front. By defining the front as described above, the mobile robot  100  can move while recognizing the surrounding environment more accurately. The mobile robot  100  according to the present embodiment also has the +X-axis direction side on which the robot camera  161  is disposed as the front, for example. 
     Alternatively, the front can be defined based on how the display unit  150  is disposed. When the display unit  150  displays the face of the character or the like, the surrounding people naturally recognize that the display unit  150  is the front of the mobile robot  100 . Therefore, when the display surface side of the display unit  150  is set as the front, there is little discomfort to the surrounding people. The mobile robot  100  according to the present embodiment also has the display surface side of the display unit  150  as the front. 
     Further, the front may be defined based on a shape of the housing of the mobile robot  100 . For example, when the projected shape of the housing unit  120  on the traveling surface is rectangular, it is better to have the short side as the front than the longitudinal side as the front, whereby people who pass by the mobile robot  100  are not obstructed during moving. That is, depending on the shape of the housing, there is a housing surface that is preferably set as the front when the mobile robot  100  moves normally. The mobile robot  100  according to the present embodiment has the short side of the rectangular shape as the front. 
     Operation of Mobile Robot 
     Next, the operation of the mobile robot  100  according to the present embodiment will be described. For example, the user turns on the power supply of the mobile robot  100 . Then, the user inputs a desired task to the operation reception unit  140 . When necessary, the ID sensor  170  identifies the ID of the user when the power supply is turned on or when the user operates the operation reception unit  140 . 
     In order to transport the object as a desired task, the user operates the operation reception unit  140  to open the storage chamber door  121  and store the object in the storage chamber. Then, the user operates the operation reception unit  140  to close the storage chamber door  121 . Next, the user inputs the destination of the object using the operation reception unit  140 . The control unit  180  of the mobile robot  100  searches for a route to the destination using the floor map stored in the storage unit  190 . The mobile robot  100  autonomously moves in the facility  900  along the searched route using the position information. 
     The mobile robot  100  may lose the acquired position information when moving along the route in the facility  900 . For example, the mobile robot  100  loses the position information due to the activation of the forced stop switch  141  for stopping the autonomous movement of the mobile robot  100 . The mobile robot  100  may be brought to an error state due to the activation of the forced stop switch  141  and may lose the position information. Further, when the forced stop switch  141  is activated, the mobile robot  100  may not be able to acquire a new mileage and a traveling direction, and may not be able to acquire accurate distance information. As a result, the mobile robot  100  loses the position information. 
     The forced stop switch  141  is activated by a hospital staff, a patient, or the like when, for example, transportation of a transported object that is more urgent than the task of the mobile robot  100  is prioritized, or when passage of a patient of the hospital is prioritized. When the forced stop switch  141  is activated, the position of the mobile robot  100  may be moved from the outside. Also due to the above, the mobile robot  100  loses the position information. 
     Next, the operation in which the mobile robot  100  that has lost the position information acquires the position information is described.  FIG. 4  is a flowchart illustrating the operation of acquiring the position information when the mobile robot  100  according to the first embodiment loses the position information due to the activation of the forced stop switch for stopping the autonomous movement. As shown in step S 101  in  FIG. 4 , the control unit  180  of the mobile robot  100  determines whether the mobile robot  100  has lost the position information due to the activation of the forced stop switch  141 . In step S 101 , when the mobile robot  100  has not lost the position information due to the activation of the forced stop switch  141 , the process ends. 
     In contrast, in step S 101 , when the mobile robot  100  has lost the position information due to the activation of the forced stop switch  141 , the control unit  180  of the mobile robot  100  determines whether the activation of the forced stop switch  141  has been released, as shown in step S 102 . For example, it is determined whether the activation of the forced stop switch  141  has been released due to the activation of the start switch  142 . In step S 102 , when the activation of the forced stop switch  141  has not been released, step S 102  is repeated. 
     In contrast, in step S 102 , when the activation of the forced stop switch  141  has been released, the mobile robot  100  acquires the position information as shown in step S 103 . Specifically, when the activation of the forced stop switch  141  is released and the autonomous movement is restored, the control unit  180  of the mobile robot  100  acquires the position information from the facility camera  400  that has captured the image of the mobile robot  100  or the other mobile robot  100 A that has detected the mobile robot  100 . 
     For example, the mobile robot  100  acquires the position information as the image data from the facility camera  400  or the other mobile robot  100 A. Further, the mobile robot  100  may acquire the position information of the other mobile robot  100 A from the mobile robot  100 A. 
     The arithmetic unit  185  calculates the position information related to the mobile robot  100  from the position information acquired from the facility camera  400  or the other mobile robot  100 A. Specifically, the arithmetic unit  185  acquires the image data of the mobile robot  100  acquired from the facility camera  400  or the other mobile robot  100 A to calculate the position information related to the mobile robot  100  and the obstacle around the mobile robot  100 . Alternatively, the arithmetic unit  185  calculates the position information of the mobile robot  100  by adding the distance information to the position information acquired from the other mobile robot  100 A. In this way, the mobile robot  100  calculates the position information including the position of the mobile robot  100  from the position information acquired from the facility camera  400  or the other mobile robot  100 A. 
     The position information acquired from the facility camera  400  in the facility  900  and the position information acquired from the other mobile robot  100 A are not directly acquired by the sensor group  160  of the mobile robot  100 . Therefore, the above position information may have a lower accuracy compared to the position information that the mobile robot  100  has directly acquired by positioning at the base point  600 . 
     Therefore, the mobile robot  100  that has acquired the position information from the facility camera  400  or the other mobile robot  100 A may move to the base point  600  fixed in the facility  900  to position at the base point  600 , thereby acquiring the base point information serving as a reference for the position information. Specifically, the control unit  180  causes the mobile robot  100  to position at the base point  600  fixed in the facility  900  to cause the mobile robot  100  to acquire the position information. Then, the control unit  180  causes the arithmetic unit  185  to calculate the position information by adding the distance information acquired from the robot camera  161  and the distance sensor  162  to the position information acquired from the base point  600  serving as an initial value. As a result, the accuracy of the position in the facility  900  can be improved. 
     The mobile robot  100  can grasp the position in the facility  900  solely from the distance information acquired from the robot camera  161  and the distance sensor  162 , without using the position information acquired from the base point  600  as the initial value. However, such position information is not based on the position information acquired from the base point  600 , thereby decreasing the accuracy of the position in the facility  900 . Even when the mobile robot  100  uses the position information acquired from the base point  600  as the initial value, with longer mileage, positional errors accumulate, thereby decreasing the accuracy of the position. Thus, it is preferable that the mobile robot  100  periodically positions at the base point  600  to acquire the position information from the base point  600 . 
     According to the present embodiment, when the mobile robot  100  has lost the position information due to the activation of the forced stop switch  141  for stopping the autonomous movement, the mobile robot  100  acquires the position information from the facility camera  400  or the other mobile robot  100 A. Thus, the mobile robot  100  can be easily restored even when losing the position information. Further, the direction information of the mobile robot  100  is acquired together with the position information. Thereby, the mobile robot  100  can be easily restored. 
     For example, when restarting the mobile robot  100  that has been forcibly stopped by the forced stop switch  141  or the like for other urgent transportations in the facility  900 , the mobile robot  100  needs to be made to acquire the position information. In this case, it is conceivable that the mobile robot  100  is caused to acquire the position information by carrying the mobile robot  100  that has been restarted to the base point  600  by the user. However, this method causes a great burden for the user. 
     In view of this, in the present embodiment, the mobile robot  100  acquires the position information from the facility camera  400  or the other mobile robot  100 A after being restarted. Thus, the mobile robot  100  can be easily restored even when losing the position information. This can also eliminate the need to install targets such as RFID tags and landmarks in advance in the facility  900  for restoring the autonomous movement of the mobile robot  100  that has lost the position information. 
     The mobile robot  100  resumes the transmission of the heartbeat signal when restoring the autonomous movement, thereby acquiring the position information via the server device  300 . Therefore, the server device  300  can easily detect the activation of the forced stop switch. 
     Furthermore, the mobile robot  100  can use the acquired position information to autonomously move to the base point  600 , in order to acquire highly accurate position information. This can reduce the burden of the user and highly accurate position information can be acquired easily. 
     Second Embodiment 
     Next, an autonomous mobile system according to a second embodiment will be described. The autonomous mobile system is a system that controls an autonomous mobile device that autonomously moves in the predetermined facility  900 , using the server device  300  and the facility camera  400 . The autonomous mobile system will be described separately in “Configuration of Autonomous Mobile System” and “Operation of Autonomous Mobile System”. 
     Configuration of Autonomous Mobile System 
     The autonomous mobile system includes the mobile robot  100 , the server device  300 , and the facility camera  400 . The autonomous mobile system may include a plurality of the mobile robots  100 . 
     Mobile Robot 
     The configuration of the mobile robot  100  according to the present embodiment is the same as that of the above-described first embodiment. The mobile robot  100  according to the present embodiment may cause the server device  300  to execute some of the functions of the mobile robot  100  according to the first embodiment. For example, the image data captured by the facility camera  400  may be acquired by the server device  300 , and the server device  300  may be made to calculate the position information of the mobile robot  100 . Further, the image data and the position information of the other mobile robot  100 A may be acquired by the server device  300 , and the server device  300  may be made to calculate the position information of the mobile robot  100 . The mobile robot  100  may acquire the position information calculated by the server device  300  from the server device  300 . 
     Server Device 
     The server device  300  is, for example, a computer having a communication function. The server device  300  may be installed at any place as long as the server device  300  can communicate with each configuration of the autonomous mobile system. The server device  300  may transmit and receive the traveling information to and from the mobile robot  100 , and may acquire the image data from the facility camera  400 . 
       FIG. 5  is a block diagram illustrating the server device according to the second embodiment. As shown in  FIG. 5 , the server device  300  includes a communication unit  330 , a control unit  380 , an arithmetic unit  385 , and a storage unit  390 . 
     The communication unit  330  communicates with the mobile robot  100  and the facility camera  400  individually. The communication unit  330  outputs a signal received from each configuration to the control unit  380 . Further, the communication unit  330  appropriately transmits a signal output from the control unit  380  to each configuration. The communication unit  330  may include a router device for performing communication between a plurality of the mobile robots  100 , the facility camera  400 , and the like. The communication unit  330  may include different communication means for performing communication between a plurality of the mobile robots  100 , the facility camera  400 , and the like. The communication unit  330  may be communicably connected to each configuration via an intranet line or the Internet line. 
     The communication unit  330  may periodically receive the heartbeat signal from the mobile robot  100 . When the transmission of the heartbeat signal is stopped and resumed, the communication unit  330  notifies the control unit  380  of the stop and resumption of the heartbeat signal. 
     The communication unit  330  may request the facility camera  400  and the other mobile robot  100 A to provide the image data of the mobile robot  100 , and receive the image data. Further, the communication unit  330  may request the other mobile robot  100 A to provide the position information, and receive the position information. The communication unit  330  transmits the position information and the like calculated from the image data to the mobile robot  100 . The communication unit  330  may transmit the direction information indicating the direction of the mobile robot  100  together with the position information of the mobile robot  100 . 
     The control unit  380  is configured by an arithmetic device such as a CPU and executes various types of information processing. The control unit  380  is notified of the stop of the heartbeat signal of the mobile robot  100  from the communication unit  330 . When the forced stop switch  141  is activated, the control unit  380  may control the communication unit  330  so that the communication unit  330  notifies the administrator of the autonomous mobile system of the activation of the forced stop switch  141 . 
     The control unit  380  is notified of the resumption of the heartbeat signal of the mobile robot  100  from the communication unit  330 . The control unit  380  causes the communication unit  330  to acquire the image data from the facility camera  400  and the other mobile robot  100 A, and to acquire the position information from the other mobile robot  100 A. Further, the control unit  380  causes the arithmetic unit  385  to calculate the position information of the mobile robot  100  from the image data, and calculate the position information of the mobile robot  100  from the position information acquired from the other mobile robot  100 A. The control unit  380  controls the communication unit  330  so that the communication unit  330  transmits the calculated position information to the mobile robot  100 . 
     The arithmetic unit  385  calculates the position information of the mobile robot  100  from the image data of the mobile robot  100 . Alternatively, the arithmetic unit  385  calculates the position information of the mobile robot  100  from the position information acquired from the other mobile robot  100 A. 
     As described above, in the case where the mobile robot  100  has lost the position information due to the activation of the forced stop switch  141  for stopping the autonomous movement, when the activation of the forced stop switch  141  is released and the autonomous movement is restored, the position information is acquired from the facility camera  400  that has captured the image of the mobile robot  100  or the other mobile robot  100 A that has detected the mobile robot  100 . Then, the position information of the mobile robot  100  is calculated from the acquired position information. In this way, the server device  300  acquires the position information of the mobile robot  100 . Subsequently, the server device  300  transmits the acquired position information to the mobile robot  100 . 
     The storage unit  390  includes a non-volatile memory such as a flash memory and an SSD. The storage unit  390  stores the floor map of the facility used by the mobile robot  100  for the autonomous movement. The storage unit  390  is connected to the control unit  380 , and outputs stored information to the control unit  380  in response to a request from the control unit  380 . 
     Operation of Autonomous Mobile System 
     Next, the operation of the autonomous mobile system will be described.  FIG. 6  is a sequence diagram illustrating the operation of the autonomous mobile system according to the second embodiment. As shown in step S 201  in  FIG. 6 , the mobile robot  100  determines whether the position information has been lost due to the activation of the forced stop switch  141 . In step S 201 , when the position information has not been lost due to the activation of the forced stop switch  141 , the process ends. 
     In contrast, in step S 201 , when the position information has been lost due to the activation of the forced stop switch  141 , the mobile robot  100  stops the transmission of the heartbeat signal that is periodically transmitted to the server device  300 , as shown in step S 202 . 
     Next, as shown in step S 203 , the mobile robot  100  determines whether the activation of the forced stop switch  141  has been released. When the activation of the forced stop switch  141  has not been released, step S 203  is repeated. 
     In contrast, in step S 203 , when the activation of the forced stop switch  141  has been released, the mobile robot  100  resumes the transmission of the heartbeat signal as shown in step S 204 . Thus, the server device  300  detects the loss of the position information of the mobile robot  100 . For example, the heartbeat signal includes the ID information and the log data of the mobile robot  100  that has lost the position information. As a result, the server device  300  can detect which mobile robot  100  has lost the position information. 
     Next, as shown in step S 205 , the server device  300  requests the facility camera  400  to provide the image data of the mobile robot  100 . In response to the request, as shown in step S 206 , the facility camera  400  transmits the image data of the mobile robot  100  to the server device  300 . 
     Alternatively, as shown in step S 207 , the server device  300  requests the other mobile robot  100 A to provide the image data or the position information of the mobile robot  100  (hereinafter referred to as “position information or the like”). In response to this, as shown in step S 208 , the other mobile robot  100 A transmits the position information or the like to the server device  300 . 
     Next, as shown in step S 209 , the server device  300  calculates the position information of the mobile robot  100  from the image data of the mobile robot  100  captured by the facility camera  400  and the mobile robot  100 A. Alternatively, the server device  300  calculates the position information of the mobile robot  100  from the position information held by the other mobile robot  100 A that has detected the mobile robot  100 . In this way, the server device  300  acquires the position information of the mobile robot  100 . 
     Subsequently, as shown in step S 210 , the server device  300  transmits the acquired position information of the mobile robot  100  to the mobile robot  100 . 
     The mobile robot  100  may improve the accuracy of the position information. For example, as shown in step S 211 , the mobile robot  100  may move to the base point  600  using the position information. Then, as shown in step S 212 , by positioning at the base point  600 , the mobile robot  100  may acquire the base point information that serves as a reference for the position information. Thus, as shown in step S 213 , the mobile robot  100  can calculate the position information based on the base point information. As a result, the mobile robot  100  moves in the facility  900  using the calculated position information. 
     According to the present embodiment, when the activation of the forced stop switch  141  is released and the autonomous movement is restored, the server device  300  calculates the position information of the mobile robot  100  from the image data of the mobile robot  100  captured by the facility camera  400  or the other mobile robot  100 A. Alternatively, the server device  300  calculates the position information of the mobile robot  100  from the position information held by the other mobile robot  100 A that has detected the mobile robot  100 . Since the server device  300  acquires the position information on behalf of the mobile robot  100 , the load on the mobile robot  100  can be reduced, and the processing speed of the mobile robot  100  can also be improved. 
     The mobile robot  100  notifies the server device  300  of the state of the mobile robot  100  such as the loss of the position information of the mobile robot  100  by stopping or resuming the transmission of the heartbeat signal. Thus, the server device  300  can immediately grasp the state of the mobile robot  100 , and perform appropriate processes for the mobile robot  100  such as the acquisition of the position information. Other configurations, operations, and effects are included in the description of the first embodiment. 
     The present disclosure is not limited to the above embodiments, and can be appropriately modified without departing from the spirit. For example, a combination of the configurations of the first and second embodiments is also included in the scope of the technical idea of the present embodiment. In addition, the autonomous mobile method and the autonomous mobile program described below are also included in the scope of the technical idea of the present embodiment. 
     APPENDIX 1 
     An autonomous mobile method for an autonomous mobile device that autonomously moves in a facility using position information, the autonomous mobile method comprising causing the autonomous mobile device to acquire the position information from a facility camera in the facility that has captured an image of the autonomous mobile device or from another autonomous mobile device that has detected the autonomous mobile device, in a case where the autonomous mobile device has lost the position information due to an activation of a forced stop switch for stopping autonomous movement of the autonomous mobile device, and when the activation of the forced stop switch is released and the autonomous movement is restored. 
     APPENDIX 2 
     The autonomous mobile method according to Appendix 1, comprising: 
     causing the autonomous mobile device to stop transmission of a heartbeat signal that is periodically transmitted to a server device communicably connected to the autonomous mobile system, when the forced stop switch is activated; and
 
causing the autonomous mobile device to resume the transmission of the heartbeat signal to acquire the position information via the server device, when the activation of the forced stop switch is released and the autonomous movement is restored.
 
     APPENDIX 3 
     The autonomous mobile method according to Appendix 1 or 2, comprising causing the autonomous mobile device to acquire direction information indicating a direction of the autonomous mobile system together with the position information. 
     APPENDIX 4 
     The autonomous mobile method according to any one of Appendices 1 to 3, comprising causing the autonomous mobile device to notify an administrator of the autonomous mobile system of the activation of the forced stop switch, when the forced stop switch is activated. 
     APPENDIX 5 
     The autonomous mobile method according to any one of Appendices 1 to 4, comprising 
     causing the autonomous mobile device that has acquired the position information to move to a base point fixed in the facility, and
 
acquire base point information that serves as a reference for the position information by causing the autonomous mobile device to position at the base point.
 
     APPENDIX 6 
     An autonomous mobile program for an autonomous mobile device that autonomously moves in a facility using position information, the autonomous mobile program causing a computer to execute acquisition of the position information by the autonomous mobile device from a facility camera in the facility that has captured an image of the autonomous mobile device or from another autonomous mobile device that has detected the autonomous mobile device, in a case where the autonomous mobile device has lost the position information due to an activation of a forced stop switch for stopping autonomous movement of the autonomous mobile device, and when the activation of the forced stop switch is released and the autonomous movement is restored. 
     APPENDIX 7 
     The autonomous mobile program according to Appendix 6, causing the computer to execute: 
     stop, by the autonomous mobile device, of transmission of a heartbeat signal that is periodically transmitted to a server device communicably connected to the autonomous mobile system, when the forced stop switch is activated; and
 
resumption, by the autonomous mobile device, of the transmission of the heartbeat signal to acquire the position information via the server device, when the activation of the forced stop switch is released and the autonomous movement is restored.
 
     APPENDIX 8 
     The autonomous mobile program according to Appendix 6 or 7, causing the computer to execute acquisition, by the autonomous mobile device, of direction information indicating a direction of the autonomous mobile system together with the position information. 
     APPENDIX 9 
     The autonomous mobile program according to any one of Appendices 6 to 8, causing the computer to execute notification, by the autonomous mobile device, of an administrator of the autonomous mobile system of the activation of the forced stop switch, when the forced stop switch is activated. 
     APPENDIX 10 
     The autonomous mobile program according to any one of Appendices 6 to 9, causing the computer to execute, by the autonomous mobile device that has acquired the position information, 
     movement to a base point fixed in the facility, and
 
acquisition of base point information that serves as a reference for the position information by causing the autonomous mobile device to position at the base point.