Abstract:
A robot system includes a supply station. The system further includes: a robot, a robot tank adapted to store a liquid and disposed at the robot; and a supply station configured to supply additional liquid to the tank.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority under 35 U.S.C. §119 from Korean Patent Application No. 2005-83561, filed Sep. 8, 2005, the entire contents of which are incorporated herein by reference. This application may also be related to commonly owned U.S. patent application Ser. No. 10/682,484, filed Oct. 10, 2003, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a mobile robot. More particularly, the present invention relates to a mobile robot system having a liquid supply station configured liquid to a mobile robot, as well as a liquid supply method for the mobile robot system. 
     2. Description of the Related Art 
     By way of explanation, a mobile robot is a robot that travels by itself and performs task. Hereafter, the term “robot” includes a “mobile robot.” 
     Generally, a robot has a power supply device that supplies power (for example, electric power), which enables the robot to move and perform a task. A rechargeable battery or a fuel cell may be used as the electric power supply device, as non-limiting examples. A non-limiting example of the fuel cell includes a methanol fuel cell. A robot using a methanol fuel cell may include a tank for storing methanol for the methanol fuel cell. When a robot using the methanol fuel cell moves or performs a given job, the robot consumes methanol. As a result, methanol stored in the tank runs out. So that the robot may continue to move, the tank should be refilled with methanol before the tank becomes empty. 
     Other robots may use water to perform their tasks. For example, robots such as steam-cleaning robots, wet mopping robots, cleaning robots, and humidifier robots may use water to perform specific jobs. Generally, these robots include at least one tank to store water to be used for performing their tasks. When the robots perform their jobs using water, water from the tank is consumed. So that the robots may continue their tasks, water should be supplied to the tank before the tank becomes empty. 
     When methanol or water in the tank runs out the robot may not operate. As a result, the robot time of use is limited. 
     SUMMARY OF THE INVENTION 
     The present invention has been developed in order to overcome the above drawbacks and other problems associated with the conventional arrangement. An aspect of the present invention is to provide a mobile robot system having a liquid supply station that automatically supplies the liquid such as water or methanol being used in the robots such that use of the robot becomes more convenient and usage hours of the robot increase. 
     To this end, a first non-limiting aspect of the present invention provides a system including a supply station, the system including: a robot; a robot tank adapted to store a liquid and disposed at the robot; and a supply station configured to supply additional liquid to the tank. 
     Another non-limiting aspect of the present invention provides robot system including a supply station, the system including: a robot including a fuel cell; a robot tank disposed at the robot and configured to store a fuel for the fuel cell; and a supply station configured to supply additional fuel based at least in part on a signal from the robot. 
     Yet another aspect provides a robot system including a supply station, the system including: a robot adapted to use water to perform a task; a robot tank disposed at the robot and configured to store the water; and a supply station adapted to supply the robot tank with additional water. 
     Another aspect of the invention provides a robot system including a supply station, the system including: a robot including fuel cell and adapted to use a liquid to complete a task; a fuel tank disposed at the robot; a liquid tank disposed at the robot; and a supply station configured to supply additional fuel and additional liquid. 
     Still another aspect of the invention provides a supply method for a robot, the method including: determining if the robot needs additional liquid; positioning the robot at a supply position of a supply station when additional liquid is required; and supplying the robot with the additional liquid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
         FIG. 1  is a view illustrating robot system having a supply station according to a first non-limiting embodiment of the present invention, 
         FIG. 2  is a view illustrating a non-limiting example of a supply nozzle unit of the robot system shown in  FIG. 1 , 
         FIG. 3  is a block diagram illustrating a non-limiting example of the operation of the robot system shown in  FIG. 1 , 
         FIG. 4  illustrates a robot system having a supply station according to a second non-limiting embodiment of the present invention, 
         FIG. 5  illustrates a non-limiting example of a supply nozzle unit of the robot system shown in  FIG. 4 , 
         FIG. 6  is a block diagram illustrating a non-limiting example of the operation of the robot system shown in  FIG. 4 , 
         FIG. 7  is a view illustrating another non-limiting example of a supply station of the robot system shown in  FIG. 4 , 
         FIG. 8  is a block diagram illustrating a non-limiting example of the operation of the supply station shown in  FIG. 7 , 
         FIG. 9  illustrated a non-limiting example of a robot system having a supply station according to a third non-limiting embodiment of the present invention, 
         FIG. 10  is a block diagram illustrating a non-limiting example of the operation of the robot system shown in  FIG. 9 , 
         FIG. 11  is a flow chart showing a supply method for a robot system having a supply station, and 
         FIG. 12  is a flow chart showing non-limiting aspects of the supply method shown in  FIG. 11 . 
     
    
    
     Throughout the drawings, like reference numerals will be understood to refer to like elements. 
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, certain exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following description, such as detailed configurations and elements thereof, are provided to assist in a comprehensive understanding of the invention. Thus, it is apparent that the present invention may be carried out in other ways known to those of skill in the art. Additionally, in the following description, well-known functions or configurations may be omitted to provide a clear and concise description of exemplary embodiments of the present invention. 
     A first non-limiting example of the present invention will be described with reference to a vacuum cleaning robot. A robot system according to the present invention may include a liquid supply station and a robot having a liquid tank. 
     The supply station supplies liquid to the liquid tank disposed in the mobile robot. The supply station may include a storage tank, a pump, a supply nozzle unit, a station controller, and a housing, among other things. The controller may control the pump and the supply nozzle unit so that liquid from the storage tank may be supplied to the tank of the robot. 
     The robot travels and performs a given job such as cleaning. The present invention is especially applicable to robots that use liquid to move or to perform a given job. For example, one type of robot obtains electrical power from a fuel cell using a liquid fuel such as methanol. Another type of robot may use water to perform tasks such as water cleaning, steam cleaning, wet mopping, or humidifying. 
       FIGS. 1 to 3  illustrate a robot system having a supply station according to a first non-limiting embodiment of the present invention. This non-limiting embodiment relates to a robot system having a supply station, such as a robot that may use a methanol fuel cell. Although this non-limiting example refers to methanol, other fuels know to those of skill in the art are within the scope of the present invention. Referring to  FIGS. 1 to 3 , the robot system  1  having the supply station according to the first embodiment of the present invention may include the supply station  10  and a robot  30  having a tank  37 . 
     The supply station  10  may be configured to supply methanol (or other fuel) to the tank  37  of the robot  30 . The supply station  10  may include a storage tank  11 , a pump  12 , a supply nozzle unit  13 , a station controller  20 , and a housing  19 . 
     The storage tank  11  may store a predetermined quantity of methanol to supply to the tank  37  of the robot  30 . The storage tank  11  may be many times larger than the tank  37  of the robot  30 . As a result, storage tank  11  may fill up the tank  37  several times. 
     The pump  12  may be in fluid communication with the storage tank  11  and may supply the tank  37  with methanol stored in the storage tank  11 . It may be preferable that the pump  12  be disposed at a lower portion of the storage tank  11 . 
     The supply nozzle unit  13  may be in fluid communication with the pump  12  and may serve as a passage through which the methanol is supplied to the tank  37 . The supply nozzle unit  13  may include a connecting pipe  14 , a supply nozzle  16 , and a nozzle drive part  15 . 
     The connecting pipe  14  may be disposed between the supply nozzle  16  and the pump  12 . The methanol being discharged by the pump  12  may flow to the supply nozzle  16  through the connecting pipe  14 . The nozzle drive part  15  may be configured to reciprocate the supply nozzle  16 . A front end of the supply nozzle  16  may be inserted into an inlet port  37   a  of the tank  37 . The nozzle drive part  15  may include a drive motor  15   a  and a drive mechanism  15   b . Any mechanism capable of converting a rotary motion of the drive motor  15   a  into a linear motion can be used for the drive mechanism  15   b . When the supply nozzle  16  is moved down by the nozzle drive part  15 , the front end of the supply nozzle  16  may be inserted into the inlet port  37   a  of the tank  37 . Therefore, when methanol is supplied from the storage tank  11  to the tank  37 , the methanol does not leak out. 
     When station controller  20  receives a supply signal from the robot  30 , the station controller  20  may control the pump  12  and the supply nozzle unit  13  to supply methanol stored in the storage tank  11  to the tank  37 . In other words, when the station controller  20  receives the supply signal from the robot  30  through receiver  21 , the station controller  20  may control the drive motor  15   a  of the supply nozzle unit  13  to insert the supply nozzle  16  into the inlet port  37   a  of the tank  37 . 
     Then the station controller  20  may start the pump  12  to supply methanol from the storage tank  11  to the tank  37 . The pump  12  may include a constant flow pump, such as a metering pump that supplies liquid at a constant rate per second. Therefore, the station controller  20  may control a quantity of liquid being supplied to the tank  37  if the station controller  20  controls operation time of the pump  12 . Also, the station controller  20  may stop the pump  12  upon receiving a stop signal from robot controller  40  of the robot  30 . 
     The housing  19  may house the storage tank  11 , the pump  12 , the supply nozzle unit  13 , and the station controller  20 . The housing  19  may fix the supply station  10  at a predetermined position. 
     Furthermore, the supply station  10  may preferably include a level sensor  23  and a display part  22 . The level sensor  23  may be disposed at the storage tank  11  and may detect a level of the liquid (e.g., methanol) stored in the storage tank  11 . The display part  22  may display a quantity of the liquid stored in the storage tank  11  an operation state of the supply station  10 , as well as other desired information. The station controller  20  may display an alarm through the display part  22  when the level of the storage tank  11  detected by the level sensor  23  is less than a desired level. This alarm may signal a need to replenish the liquid in the storage tank  11 . 
     The robot  30  may travel by itself and may perform a given job using power obtained from the methanol fuel cell  36 . The robot  30  may include a suction part  31 , a driving part  32 , a transmitting-receiving part  33 , a position detection part  35 , a station detection part  34 , a fuel cell  36 , a tank  37 , a fuel remaining detection part  39 , and a robot controller  40 . 
     The suction part  31  may clean a surface on which the robot  30  is traveling by sucking in contaminants from the surface. The suction part  31  may have a vacuum generator configured to generate a suction force and a dust collecting unit configured to separate and collect the contaminants. 
     The driving part  32  enables the robot  30  to move in any direction. The driving part  32  may generally include plurality of wheels  32   a  and a plurality of motors (not shown) that drive the plurality of wheels  32   a.    
     The transmitting-receiving part  33  may receive a control signal being transmitted from a remote control apparatus (not shown) and may transmit a supply signal of the robot controller  40  to the supply station  10 . 
     The position detection part  35  may detect a current location of the robot  30 . The position detection part  35  may use a general position detecting method such as a position detecting method using a vision camera and/or a vision board. 
     The station detection part  34  may detect the position of the supply station  10 . A camera and/or a vision board may be included in the station detection part  34 . Also, ultrasonic sensors or laser sensors may be included in the station detection part  34 . Transmitters for the ultrasonic sensors or laser sensors may be disposed at the supply station  10 . 
     The fuel cell  36  may supply the robot  30  with power for operating. While various types of fuel cells may be used, this non-limiting embodiment uses methanol fuel cell  36 . 
     The tank  37  may be configured to store a predetermined quantity of methanol that is consumed as the robot  30  operates. The tank  37  may include inlet port  37   a  into which the supply nozzle  16  is inserted at upper portion of the tank  37 . Also, the inlet port  37   a  may preferably include inlet port cap  38  that may be opened and closed by the supply nozzle  16 . In other words, when the supply nozzle  16  descends, the inlet port cap  38  may be opened and the supply nozzle  16  may be inserted into the interior of the inlet port  37   a . When the supply nozzle  16  rises, the inlet port  37   a  may be closed automatically to prevent the liquid being stored in the tank  37  from flowing out or vaporizing out through inlet port  37   a . The inlet port cap  38  according to the present non-limiting embodiment may have two cap doors  38   a  elastically supported by an elastic member (not shown). When the supply nozzle  16  descends, the cap doors  38   a  may move down and the supply nozzle  16  may be inserted into inlet ports  37   a . When the supply nozzle  16  rises, the cap doors  38   a  may be moved up by the elastic member and to close the inlet port  37   a , as shown in  FIG. 1 . The inlet port cap  38  may include any suitable inlet port cap. For example, an inlet port cap for a fuel tank of a car may be used. The fuel remaining detection part  39  may detect a quantity of methanol remaining in the tank  37  and may send a fuel remaining signal to the robot controller  40 . 
     The robot controller  40  may be configured to interpret control signals that the transmitting-receiving part  33  receives. According to the received control signals, the robot controller  40  may control the suction part  31 , the driving part  32 , the position detection part  35 , and the station detection part  34  to move or to perform a given job. 
     Furthermore, the robot controller  40  may ascertain a quantity of the fuel stored in the tank  37  through signals received from the fuel remaining detection part  39 . When the level of the fuel in tank  37  falls below a certain level, the robot controller  40  may move the robot  30  to the supply station  10  to refuel. In other words, after the robot controller  40  recognizes a location of the supply station  10  via the station detection part  34 , the robot controller  40  may control the driving part  32  so that the robot  30  moves to the supply station  10 . The robot may move to a position proximate to the supply station  10  such that the inlet port  37   a  of the tank  37  of the robot  30  is located near the supply nozzle  16  of the supply station  10 . The robot controller  40  may transmit a supply request signal to the supply station  10 . The station controller  20  may then control the pump  12  and the supply nozzle unit  13  to supply the tank  37  with the fuel from tank  11 . When the level of fuel in the tank  37  reaches a desired level, the robot controller  40  may transmit a stop request signal to the supply station  10 , so that the supply station  10  stops supplying methanol. 
     The robot  30  may determine that a level of fuel stored in tank  37  is below a certain (low threshold) level. The low threshold level may be determined based on the specifications for the tank  37  and the fuel cell  36 . 
     When the level of fuel in tank  37  is lower than the low threshold, the robot controller  40  of the robot  30  may locate supply station  10  using station detection part  34 . Robot controller  40  may then move the robot  30  to the liquid supply station  10 . At this time, the supply nozzle  16  of the liquid supply station  10  may be at an upper position, as shown in  FIG. 1 . The robot controller  40  may use methods known to those of skill in the art to position the robot  30  at the supply position. 
     When the robot  30  reaches the supply position, the robot controller  40  may transmit a supply signal to the supply station  10  through the transmitting-receiving part  33 . The receiver  21  of the supply station  10  may receive a supply signal from robot  30  and may send it to the station controller  20 . The station controller  20  may control the nozzle drive part  15  of the supply nozzle unit  13  to move the supply nozzle  16  down. When the supply nozzle  16  descends, the front end of the supply nozzle  16  pushes the cap doors  38   a  of the inlet port cap  38  so that it enters the inlet port  37   a  of the tank  37 , as shown in  FIG. 2 . 
     When the supply nozzle  16  is inserted into the inlet port  37   a , the station controller  20  may signal the pump  12  to begin pumping. When the pump  12  operates, fuel from the storage tank  11  may be supplied to the tank  37  through the connecting pipe  14  and the supply nozzle  16 . The station controller  12  may signal the pump  12  to stop after a desired time has elapsed (which may be predetermined) or when it receives a stop signal from the robot controller  40 . The station controller  20  may return the supply nozzle  16  to its original position. After refueling is completed, the robot controller  40  of the robot  30  may control the driving part  32  to resume the given job. 
       FIGS. 4 to 6  show a robot system having a supply station according to a second non-limiting embodiment of the present invention. The second non-limiting embodiment relates to a robot system  50  having a supply station for robot  80 , which is fueled by a rechargeable battery and uses a liquid, such as water, to complete at least one task. The robot system  50  having the supply station may include supply station  60  and robot  80 , which may have a tank  87 . 
     The supply station  60  may be configured to supply tank  87  with a liquid useful for completing at least one task. In this non-limiting example, water is provided. However, other suitable liquids may also be provided. The supply station  60  may include storage tank  61 , pump  62 , supply nozzle unit  63 , recharging part  74 , station controller  70 , and housing  69 . 
     The storage tank  61  may be configured to store a predetermined quantity of water to supply to the tank  87  of the robot  80 . The storage tank  61  may be connected to a water service pipe  68  to obtain water. The water service pipe  68  may have a valve  67  (such as an automatic valve) that opens and closes the water service pipe  68 . It is convenient to supply storage tank  61  with water when the storage tank  61  is connected to the water service pipe  68  with the automatic valve  67 . The water pressure being applied to the pump  62  may be maintained within a desired range because the storage tank  61  maintains a desired quantity of water in storage. Therefore the pump  62  may supply a constant quantity of water from the storage tank  61  to the tank  87 . 
     The recharging part  74  may be configured to recharge the rechargeable battery  86  of the robot  80  according to a signal from the station controller  70 . The recharging part  74  may include recharging terminals  75  connected to battery terminals  86   a.    
     The pump  62 , the supply nozzle unit  63 , the station controller  70 , and the housing  69  may be the same or similar to that described above in the first non-limiting embodiment. The nozzle drive part  65  of the supply nozzle unit  63  may have drive motor  65   a  and drive mechanism  65   b . When water in the storage tank  61  becomes lower than a desired level, the station controller  70  may control the automatic valve  67  to open so that water flows from the water service pipe  68  to the storage tank  61 . 
     Furthermore, the supply station  60  may preferably include a level sensor  73  and a display part  72 . The level sensor  73  may be disposed at the storage tank  61  and may detect a level of the liquid (e.g., water) stored in the storage tank  61 . The display part  72  may display a quantity of the liquid stored in the storage tank  61  an operation state of the supply station  60 , as well as other desired information. The station controller  70  may display an alarm through the display part  72  when the level of the storage tank  61  detected by the level sensor  73  is less than a desired level. This alarm may signal a need to replenish the liquid in the storage tank  61 . 
     The robot  80  may be configured to travel and to perform a desired task using power obtained from the rechargeable battery  86 . The robot  80  may include suction part  81 , driving part  82 , transmitting-receiving part  83 , position detection part  85 , station detect part  84 , rechargeable battery  86 , tank  87 , a fluid remaining detection part  89 , humidifier  91 , and robot controller  90 . 
     The rechargeable battery  86  may supply robot  80  with power to operate. Rechargeable battery  86  may include recharge detection part  88  configured to detect a state of the rechargeable battery  86 . When a power level of the rechargeable battery  86  falls below a desired capacity, the recharge detection part  88  may send a recharge signal to the robot controller  90 . As such, the rechargeable battery  86  may be recharged. Methods of recharging a rechargeable battery  86  known to those of skill in the art are within the scope of the present invention. 
     The tank  87  may store a predetermined quantity of fluid that the robot  80  may use to perform a desired task. The tank  87  may include an inlet port  87   a  into which the supply nozzle  66  may be inserted at an upper portion of the liquid tank  87 . The inlet port  87   a  may be substantially formed as a funnel. Although not shown, the inlet port cap  38  may be disposed in the inlet port  87   a  as in the first non-limiting embodiment described above, if desired. The fluid remaining detection part  89  may be configured to detect a level of fluid stored in the tank  87  and may send a signal indicating a detected fluid level to the robot controller  90 . 
     In this non-limiting example, the task to be performed by the robot  80  includes humidifying. Accordingly, robot  80  may include a humidifier  91 . The humidifier  91  increases the amount of moisture in the air according to a signal from robot controller  90 . The tank  87  may supply humidifier  91  with water. 
     The robot controller  90  may be configured to interpret control signals received by transmitting-receiving part  83 . According to the received control signals, the robot controller  90  may control suction part  81 , driving part  82 , position detection part  85 , and the station detection part  84  so that the mobile robot  80  moves or performs the desired task. The robot may be controlled to perform desired tasks, as known to those of skill in the art. 
     Furthermore, the robot controller  90  may ascertain a quantity of fluid stored in tank  87  through the fluid remaining detection part  89 . When the water level of the tank  87  falls below a desired level, the robot controller  90  may move the mobile robot  80  to the supply station  60  so that the storage tank  61  may supply tank  87  with water. The manner in which the robot controller  90  may control mobile robot  80  to be supplied with water from the storage tank  61  may be similar to that of supply of fluid in the first non-limiting embodiment described above. 
     Hereinafter, operations of the mobile robot system  50  according to the second non-limiting embodiment will be described. The robot  80  may determine if a level of fluid stored in tank  87  falls below a desired level. The desired level may be determined by specifications of tank  87  and humidifier  91 . 
     When tank  87  is ready for refilling, the robot controller  90  of the robot  80  may signal the robot  80  to stop its task. Robot controller  90  may locate the supply station  60  via the station detection part  84 . Robot controller  90  may cause the mobile robot  80  to move to a supply position at supply station  60 . Supply nozzle  66  of the supply station  60  may be at an upper position, as shown in  FIG. 4 . 
     When the mobile robot  80  locates the supply position, the robot controller  90  may transmit a supply signal to the liquid supply station  60  through the transmitting-receiving part  83 . The receiver  71  of the supply station  60  may receive a supply signal from the robot  80  and may send it to the station controller  70 . The station controller  70  may then drive the nozzle part  65  of the supply nozzle unit  63  to move the supply nozzle  66  down. When the supply nozzle  66  lowers, a front end of the supply nozzle  66  may be inserted into the inlet port  87   a  of the tank  87 , as shown in  FIG. 5 . 
     When the supply nozzle  66  is inserted into inlet port  87   a , the station controller  70  may start operation of pump  62 . When pump  62  operates, water from the storage tank  61  may be supplied to tank  87  through the connection pipe  64  and the supply nozzle  66 . Then the station controller  70  stops the pump  62  after a desired time or when it receives a stop signal from the robot controller  90 . After resupply is completed, the robot controller  90  of the mobile robot  80  may control the driving part  82  to resume the desired task. 
     A quantity of water stored in the storage tank  61  of the supply station  60  decreases when supply station  60  supplies water to tank  87 . The station controller  70  may detect a level of water in the storage tank  61  via level sensor  73 . When level of liquid in tank  61  falls below a desired level, the station controller  70  may open the valve  67 . Then water flowing out of the water service pipe  68  may fill the storage tank  61 . When the fluid level in the storage tank  61  reaches a desired level, the station controller  70  may close the valve  67  to stop supply of fluid. 
       FIGS. 7 and 8  show another non-limiting embodiment of the liquid supply station. The liquid supply station  60 ′ may have water service pipe  68 , which may be directly connected to the supply nozzle unit  63 . The valve  67  may be disposed between the supply nozzle unit  63  and the water service pipe  68  to open or close the water service pipe  68 . The liquid supply station  60 ′ may not include the storage tank  61  and the pump  62  of the non-limiting second embodiment. Therefore, when supplying water to the tank  87  of the robot  80 , the water may be directly supplied from water service pipe  68  to tank  87 . 
     Referring to  FIGS. 7 and 8 , liquid supply station  60 ′ may include supply nozzle unit  63  directly connected to water service pipe  68 . When receiving a supply signal from the robot controller  90 , the station controller  70 ′ may open valve  67  (such as an automatic valve) so that water flows from water service pipe  68  to tank  87 . When receiving a stop signal from the robot controller  90 , the station controller  70  may close the valve  67  to stop the flow of water. 
     Although the robot  80  described above may include humidifier  91  as an apparatus using fluid from tank  87 , this is for illustrative purposes only. The robot  80  may additionally or alternatively include a water cleaning apparatus, a steam cleaning apparatus, a wet mopping apparatus, as well as other fluid cleaning devices known to those of skill in the art. 
       FIGS. 9 and 10  illustrate a robot system having a supply station according to a third non-limiting embodiment of the present invention. The third non-limiting embodiment includes a robot system  100  having a supply station for a robot that obtains power from a methanol fuel cell and performs a desired task using water. 
     Robot system  100  having a liquid supply station according to the third non-limiting embodiment includes a supply station  110  and a robot  140  having fuel (e.g., methanol) tank  147  and a fluid (e.g., water) tank  151 . The supply station  110  may supply tank  147  and tank  151  of the robot  140  with methanol (or other fuels) and water (or other desired fluids), respectively. The supply station  110  may include storage tank  111 , a storage tank  121 , first and second pumps  112  and  122 , first and second supply nozzle units  113  and  123 , station controller  130 , and housing  119 . 
     The storage tank  111  may store a predetermined quantity of fuel (e.g., methanol) to supply to tank  147  of robot  140 . The storage tank  121  may provide a predetermined quantity of fluid to tank  151  of robot  140 . The storage tank  121  may be connected to a water service pipe  128  to supply water. The water service pipe  128  may have an valve  127  (such as an automatic valve) that opens and closes the water service pipe  128 . Connection of the storage tank  121  and the water service pipe  128  having the automatic valve  127  makes it convenient to supply the storage tank  121  with water. 
     The first pump  112  may be in fluid communication with the storage tank  111  and may supply tank  147  with the fuel (e.g., methanol) stored in the storage tank  111 . It may be preferable that the first pump  112  be disposed at a lower portion of the storage tank  111 . The second pump  122  may be in fluid communication with the storage tank  121  and may supply tank  151  with the fluid stored in the storage tank  121 . It may be preferable that the second pump  122  be disposed at a lower portion of the storage tank  121 . 
     The first and second supply nozzle units  113  and  123  may be in fluid communication with the first and second pump  112  and  122  and may serve as passages through which the fuel and the fluid flow to tank  147  and tank  151 , respectively. The first and second supply nozzle units  113  and  123  may include first and second connect pipes  114  and  124 , first and second supply nozzles (not shown), and first and second nozzle drive parts  115  and  125 , respectively. 
     The first connect pipe  114  may be disposed between the first supply nozzle and the first pump  112 . The methanol discharged by the first pump  112  may flow to the first supply nozzle through the first connect pipe  114 . The second connect pipe  124  may be disposed between the second supply nozzle and the second pump  122 . The fluid discharged by the second pump  122  may flow to the second supply nozzle through the second connect pipe  124 . 
     The first and second nozzle drive part  115  and  125  may reciprocate the first and second supply nozzles, respectively, up and down in a straight line. Each front end of the first and second supply nozzle may be inserted into inlet ports of tank  147  and tank  151 . The first and second nozzle drive parts  115  and  125  each may have a drive motor and a drive mechanism. Any mechanism capable of converting a rotary motion of the drive motor into an up and down linear motion of the supply nozzle can be used for the drive mechanism. 
     When the first and second supply nozzles are moved down by the first and second nozzle drive parts  115  and  125 , respectively, each front end of the first and second supply nozzle may be inserted into each inlet port of tank  147  and tank  151 . Therefore, when the fuel and the fluid are supplied from the storage tank  111  and the storage tank  121  to tank  147  and tank  151 , the fuel and the fluid do not leak out. 
     When the station controller  130  receives a supply signal from the robot  140 , the station controller  130  may control the first and second pumps  112  and  122  and the first and second supply nozzle units  113  and  123  to supply the fuel and the fluid stored in the storage tank  111  and the storage tank  121  to tank  147  and tank  151 . In other words, when the station controller  130  receives a fuel supply signal from the mobile robot  140  through receiver  131 , the station controller  130  may control the first nozzle drive part  115  of the first supply nozzle unit  113  to insert the first supply nozzle into the inlet port of the tank  147 . Then the station controller  130  may start the first pump  112  to supply the fuel from storage tank  111  to tank  147 . 
     When the station controller  130  receives a fluid supply signal from the robot  140  through the receiver  131 , the station controller  130  may control the second nozzle drive part  125  of the second supply nozzle unit  123  to insert the second supply nozzle into the inlet port of the tank  151 . Then the station controller  130  may start the second pump  122  to supply fluid from tank  121  to tank  151 . The first and second pump  112  and  122  may include constant flow pumps such as metering pumps that supply liquid at a constant rate per second. Therefore, the station controller  130  may control a quantity of fuel and fluid supplied to the tank  147  and the tank  151  if the station controller  130  controls operation time of the first and second pumps  112  and  122 , respectively. Also, the station controller  130  may stop either of the first and second pumps  112  and  122  when receiving a stop signal from a robot controller  150  of the robot  140 , thereby controlling a quantity of fuel and fluid being supplied to tank  147  and tank  151 . 
     The housing  119  may house storage tank  111 , storage tank  121 , first and second pumps  112  and  122 , first and second supply nozzle units  113  and  123 , and station controller  130 . The housing  119  may fix the supply station  110  at a predetermined position. 
     Furthermore, the supply station  110  may preferably include first and second level sensors  133  and  134  and a display part  132 . The first and second level sensors  133  and  134  may be disposed at storage tank  111  and storage tank  121 , respectively, and may detect levels of fuel and fluid stored in the storage tank  111  and the storage tank  121 , respectively. The display part  132  may display a quantity of the fuel and the fluid being stored in the storage tank  111  and the storage tank  121 , respectively, as well as an operation state of supply station  110 . The station controller  130  may display an alarm through the display part  132  when a fuel level in the storage tank  111  being detected by the first level sensor  133  and/or a fluid level in the storage tank  121  being detected by the second level sensor  134  are less than a desired level. 
     The robot  140  may travel by itself and perform a desired task using power obtained from a power source such as methanol fuel cell  146 . The robot  140  may include suction part  141 , driving part  142 , transmitting-receiving part  143 , position detection part  145 , station detection part  144 , the methanol fuel cell  146 , fuel tank  147 , a fuel remaining detection part  148 , fluid tank  151 , fluid remaining detection part  152 , humidifier  153 , and robot controller  150 . 
     The robot  140  may be substantially the same as or similar to robot  80  described in the non-limiting second embodiment, except that it may have tank  147  and fuel remaining detection part  148 . The methanol fuel cell  146 , the fuel tank  147 , and the fuel remaining detection part  148  may be similar to the first non-limiting embodiment of the present invention. 
     According to a third non-limiting embodiment, illustrated in  FIGS. 9 and 10 , the robot  140  may determine if a level of the fluid stored in tank  151  falls below a desired fluid level via fluid remaining detection part  152 . Also the mobile robot  140  may determine if a level of the fuel stored in tank  147  falls below a desired fuel level via the fuel remaining detection part  148 . The desired fluid level and the desired fuel level are respective quantities of the fluid and the fuel that tank  151  and tank  147  may be determined by specifications of the tank  151 , the humidifier  153 , the tank  147 , and the fuel cell  146 . 
     The procedure with which the mobile robot  140  obtains fuel and/or fluid may be substantially the same as those of the first and second non-limiting embodiments described above. However, the robot  140  may simultaneously fill up tank  147  with fuel while filling up tank  151  with fluid, according to the non-limiting third embodiment. As a result, a frequency at which robot  140  returns to the supply station  110  is reduced, and a working time of the robot increases. 
     Another aspect of the present invention is illustrated in  FIGS. 11 and 12 . In the robot system  1 ,  50 , or  100  having supply station  10 ,  60 , or  110 , the robot  30 ,  80 , or  140  may detect a level of the liquid being stored in the tank  37 ,  87 ,  147 , or  151  and may determine if tank  37  or  87  is low (Step S 10 ). When tank  37 ,  87 ,  147 , or  151  is low, robot  30 ,  80 , or  140  may stop its task and may move to a supply position at the supply station  10 ,  60 , or  110  (Step S 20 ). 
     When the robot  30 ,  80 , or  140  locates the supply position of the supply station  10 ,  60 , or  110 , the supply station  10 ,  60 , or  110  supplies the robot  30 ,  80 , or  140  with the liquid (Step S 30 ). Referring to  FIG. 12 , the procedure of supplying the liquid will be described in detail. When the robot  30 ,  80 , or  140  is positioned at the supply position, a robot controller  40 ,  90 , or  150  of the robot  30 ,  80 , or  140  may transmit a supply signal to the liquid supply station  10 ,  60 , or  110  (Step S 31 ). 
     Upon receiving the supply signal, the supply station  10 ,  60 , or  110  may insert a supply nozzle  16  or  66  into an inlet port of the tank  37 ,  87 ,  147 , or  151  of the robot  30 ,  80 , or  140  (Step S 32 ). In other words, when a station controller  20 ,  70 , or  130  of the supply station  10 ,  60 , or  110  receives the supply signal, it may control a nozzle drive part of the supply nozzle unit  13 ,  63 ,  113 , or  123  to move the supply nozzle  16  or  66  down. Then the supply nozzle  16  or  66  may be inserted into the inlet port of the tank  37 ,  87 ,  147 , or  151  of the robot  30 ,  80 , or  140 . 
     When supply nozzle  16  or  66  is inserted into the inlet port of the tank  37 ,  87 ,  147 , or  151 , the supply station  10 ,  60 , or  110  may supply the tank  37 ,  87 ,  147 , or  151  with liquid through the supply nozzle  16  or  66  (Step S 33 ). In other words, when the station controller  20 ,  70 , or  130  of the supply station  10 ,  60 , or  110  operates the pump  12 ,  62 ,  114 , or  124 , the liquid of the tank  11 ,  61 ,  111 , or  121  is supplied to the tank  37 ,  87 ,  147 , or  151  of the robot  30 ,  80  or  140  through a connection pipe  14 ,  64 ,  114 , or  124  and the supply nozzle  16  or  66 . 
     When re-supply of the liquid is completed, the supply station  10 ,  60 , or  110  may remove the supply nozzle  16  or  66  from the inlet port of the robot  30 ,  80 , or  140  (Step S 34 ). In other words, when the tank  37 ,  87 ,  147 , or  151  of the robot  30 ,  80 , or  140  is filled with liquid, the station controller  20 ,  70 , or  130  of the supply station  10 ,  60 , or  110  may control the nozzle drive part to move the supply nozzle  16  or  66 . Then the supply nozzle  16  or  66  may be removed from the inlet port of the tank  37 ,  87 ,  147  or  151 . When the supply nozzle  16  or  66  is removed, the robot  30 ,  80 , or  140  may resume the desired task. 
     While these non-limiting embodiments have described automatic refueling and refilling of fluid tanks, manual refueling and refilling are also within the scope of the present invention. While non-limiting embodiments of the present invention have been described, additional variations and modifications of the embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims shall be construed to include both the above embodiments and all such variations and modifications that fall within the spirit and scope of the invention.