Patent Publication Number: US-2016246301-A1

Title: Transport Vehicle Control Device and Transport Vehicle Control Method

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a U.S. National Stage Application under 35 U.S.C §371 of International Patent Application No. PCT/JP2013/077733 filed 11 Oct. 2013, the disclosures of all of which are hereby incorporated by reference in their entities. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a transport vehicle control device and a transport vehicle control method. 
     BACKGROUND ART 
     Moving stored articles within a warehouse has vastly been automated. For example, in a large-scale warehouse, unmanned transport vehicles move stored articles. 
     In an example of Japanese Translation of PCT international Application Publication No. 2009-541176 (such as in paragraphs 0042 and 0043), “inventory holders” are arranged in a warehouse in a grid pattern that are containers in which articles are stored. A “mobile drive unit” capable of propelling itself through passages between the inventory holders moves the articles by lifting the “inventory holders.” Then, a “management module” generates a route for the mobile drive unit to take, according to the state of the working space and the state of the mobile drive unit. 
     SUMMARY OF THE INVENTION 
     Problems to be Solved 
     An environment in the warehouse changes in real time. For example, it is assumed that many transport vehicles are used at the same time, each transporting a shelf in which articles are stored. Then, there can be a sequence of events at a certain place such that there is a shelf at some point of time, the shelf no longer exists at the next point of time, and then the shelf is returned after that. In addition, there can be a case where articles that have fallen on the floor in the course of transportation interfere with the transport vehicles running. 
     The technique of Japanese Translation of PCT International Application Publication No. 2009-541176 (such as in paragraphs 0042 and 0043) is not flexible enough to reflect changes in the environment for planning a route, and then not suitable for revising the planned route in real time. In addition, the mobile drive unit returns the inventory holder to the original position. This causes a mobile drive unit to travel the same route many times for transporting the same articles, and then to have lower transportation efficiency if the route is no longer the shortest route. 
     Accordingly, the present invention is intended to revise a route for a vehicle in real time and to revise a location for a shelf to be returned depending on the usage frequency of articles. 
     Solution to Problems 
     A transport vehicle control device of the present invention includes: a storage portion that stores map information in which a state of a cell where a rack is arranged is saved for each cell; a data transceiver that receives the latest state of the cell from a transport vehicle which transports the rack; a map manager that updates the map information, each time the data transceiver receives the latest state of the cell, using the latest state of the cell received; and a route searcher that searches for a route for the transport vehicle transporting the rack based on the map information updated. 
     The transport vehicle control device of the present invention further includes a cell-for-rearranged-rack determiner that determines a cell into which the rack is rearranged on the basis of a usage frequency of articles to be stored on the rack. 
     Others will be described in the detailed description of embodiments. 
     Advantageous Effects of the Invention 
     The present invention allows for revising a route for a transport vehicle in real time, and revising the location for a shelf to be returned depending on the usage frequency of articles. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a perspective view of a shelf; 
         FIG. 1B  is a perspective view of a transport vehicle; 
         FIG. 2A  is an illustration of an exemplary arrangement of shelves; 
         FIG. 2B  is an example of an overall floor plan of a warehouse; 
         FIG. 3  is another example of an overall floor plan of the warehouse; 
         FIG. 4  is a block diagram of the transport vehicle control device and the transport vehicle; 
         FIG. 5A  is a chart showing an example of map information; 
         FIG. 5B  is a chart showing an example of article information; 
         FIG. 5C  is a chart showing an example of a report transmitted by the transport vehicle to the transport vehicle control device; 
         FIG. 6A  is a chart showing an example of route information; 
         FIG. 6B  is an illustration of a practical example of an instruction route and instruction operation; 
         FIG. 7  is a sequence chart showing communications between the transport vehicle control device and two or more transport vehicles; 
         FIG. 8  is a flowchart of a map information update procedure; 
         FIG. 9A  is a flowchart of a cell-for-rearranged-shelf determination procedure; 
         FIG. 9B  is a flowchart of a shelf rearrangement procedure; and 
         FIGS. 10A, 10B, and 10C  are illustrations of a shelf rearrangement procedure. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment according to the invention will be described with reference to the drawings as appropriate. 
     [Shelf and Transport Vehicle] 
     Appearances of a shelf  51  will be described with reference to  FIG. 1A . The shelf  51  includes a storage portion  52  having a square shape in a plan view, for example, and four legs  53 . The storage portion  52  has one or more stages (upper and lower stages in an example in  FIG. 1A ) to keep articles on each of the stages. 
     Appearances of a transport vehicle  2  will be described with reference to  FIG. 1B . The transport vehicle  2  includes a shelf support table  62  in a disk shape, a shelf support column  63  in a cylindrical shape, a body  64  having a square shape in a plan view, for example, and four wheels  65 . The shelf support table  62  lifts a bottom surface of the storage portion  52  of the shelf  51 . The shelf support column  63  is a member that connects the shelf support table  62  with the body  64 . The shelf support column  63  is capable of freely varying its height. The wheel  65  is capable of freely changing directions. Note that the “rack” is equivalent to the shelf. 
     A diameter  66  of the shelf support table  62  and a length  67  of one side of the body  64  are shorter than a distance  54  between the two adjacent legs  53  of the shelf  51 . As the height of the shelf support column  63  varies, an overall height  68  of the transport vehicle  2  varies. When the transport vehicle  2  travels alone without supporting the shelf  51 , the height  68  is shorter than a height  55  of the leg  53  of the shelf  51 . That is, the transport vehicle  2  is capable of travelling on the floor between the legs  53  under the storage portion  52  of the shelf  51 , without contacting the rack  51 . When the transport vehicle  2  travels with supporting (in a state of lifting) the shelf  51 , the height  68  is longer than the height  55  of the leg  53  of the shelf  51 . That is, the transport vehicle  2  is capable of transporting the shelf  51 , in a state of the leg  53  of the shelf  51  being lifted from the floor. 
     [Shelf Arrangement] 
     An exemplary arrangement of the shelves  51  will be described with reference to  FIG. 2A . The shelves  51  are arranged in a grid pattern on the floor of the warehouse. Typically, a plurality of shelves  51  are arranged (as viewed from above) so as to form rectangular blocks. 
     An example of an overall floor plan of the warehouse will be described with reference to  FIG. 2B . The floor of the warehouse is managed as a set of squares in accordance with the shape of the shelf  51 . Each square is referred to as a “cell.” The length of one side of the cell is slightly longer than the length  56  of one side of the storage portion  52  of the shelf  51 . In  FIG. 2B , cells are regularly arranged in 15 rows by 10 columns. Each cell has a cell ID such as “R0110” for uniquely identifying itself. With the cell ID “R0110” for the cell at the upper right corner in  FIG. 2B , “01” is to identify the row and “10” is to identify the column. That is, the cell ID also indicates position information of the cell. 
     The twelve shelves  51  are arranged in a rectangular area having a cell “R0303” at the upper left corner and a cell “R0804” at the lower right corner. Similarly, the twelve shelves  51  are also arranged in a rectangular area having a cell “R0307” at the upper left corner and a cell “R0808” at the lower right corner. 
     A rectangular area having a cell “R1103” at the upper left corner and a cell “R1205” at the lower right corner is a picking area. The transport vehicle  2  transports a shelf  51  from a certain cell to the picking area. Then, a worker in the picking area takes out articles from the shelf  51 . Typically, the shelf  51  is managed under an air-conditioning requirement depending on the nature of the articles to be stored (cold in case of food). The picking area is managed under an air-conditioning requirement for the worker to have the highest working efficiency (partitions or the like are not shown). 
     A rectangular area having a cell “R1107” at the upper left corner and a cell “R1208” at the lower right corner is a work area. The transport vehicle  2  transports a shelf  51  from a certain cell into the work area. Then, the worker in the work area executes a predetermined work. The predetermined work means, for example, packaging, inspecting, tagging, or measuring a weight of, articles. 
     Cells “R1402,” “R1502,” “R1409,” and “R1509” are transport-vehicle waiting areas. The transport vehicle  2  waits in the transport-vehicle waiting area during a time when there is no specific transportation work. 
     The shelf  51  can be placed in any cell other than “placement disallowed” cells belonging to a shelf-placement-disallowed area to be described later. Among the transport vehicles  2 , those transporting the shelves  51  are referred to as “loaded vehicles.” On the other hand, those not transporting the shelves  51  are referred to as “unloaded vehicles.” The unloaded vehicles can travel in any cells other than “non-travelable” cells to be described later. The loaded vehicle can travel in any cell which is other than “non-travelable” cell to be described later, and is in a “no shelf” state to be described later. 
     Another example of an overall floor plan of the warehouse will be described with reference to  FIG. 3 . The shelf-placement-disallowed areas are such as those located in front of the entrance or right under an access panel on the ceiling, where the shelves  51  are not allowed to be arranged. A provisional storage area is an area where those shelves  51  frequently picked are temporarily placed (to be described later in detail). For illustration purpose, respective areas are separately described in  FIG. 2B  and  FIG. 3 . Of course, those areas shown in  FIG. 2B  and those areas shown in  FIG. 3  are present at the same time on the same floor, without each area having any overlapping. 
     Configurations of a transport vehicle control device  1  and the transport vehicle  2  will be described with reference to  FIG. 4 . The transport vehicle control device  1  is a general purpose computer. The transport vehicle control device  1  includes a central control unit  11 , an input device  12  such as a keyboard and a mouse, an output device  13  such as a display, a main memory  14 , an auxiliary storage device  15 , and a communication device  16 . These are interconnected by a bus. A data transceiver  21 , a map manager  22 , a route searcher  23 , a cell-for-rearranged-shelf determiner  24 , and a shelf rearranger  25  are programs loaded into the main memory  14 . Hereinbelow, in a case where one of these components is described as a subject, it means that the central control unit  11  retrieves each program from the auxiliary storage device  15 , loads it into the main memory  14 , and then embodies a function of each program (to be described later in detail). The auxiliary storage device  15  stores map information  31 , article information  32 , and route information  33  (to be described later in detail). The transport vehicle control device  1  may communicatively be connected via a wireless network  3  to one or more transport vehicles  2 . 
     The transport vehicle  2  includes a microcomputer  41 , a communication device  42 , a sensor  43 , a tag reader  44 , a power unit  45 , and a battery  46 . These are interconnected by a bus or a power line. The sensor  43  radiates ultrasonic waves or photographs images of its surroundings, for example, to detect the presence of obstacles (fallen articles etc.) in a cell. The tag reader  44  reads information (such as a shelf ID and an article ID to be described later) stored in a tag, for example, affixed to a portion of the shelf  51 . The power unit  45  is, for example, a motor for driving the wheel  65 , a motor for controlling the direction of the wheel  65 , a motor for changing the length of the shelf support column  63 . The battery  46  supplies power as power source for these motors. 
     The microcomputer  41  includes a central control unit, a main memory, and an auxiliary storage (not shown). A data transceiver  26  and a power manager  27  are programs. The central control unit retrieves each program from the auxiliary storage, loads it into the main memory, and then embodies a function of each program. 
     [Map Information] 
     The map information  31  will be described with reference to  FIG. 5A . The map information  31  is stored with, in association with a cell ID stored in a cell ID field  111 , a state of a cell in a cell state field  112 , the shelf ID in a shelf ID field  113 , an article ID in an article ID field  114 , and a remark in a remark field  115 . 
     The cell ID in the cell ID field  111  is, as described above, an identifier for uniquely identifying the cell. 
     A state of a cell in the cell state field  112  is a current state of the cell, and indicates one of the following four states. 
     “No Shelf:” this indicates that there is no shelf  51  in the cell;
 
“With shelf:” this indicates that there is a shelf  51  in the cell;
 
“Placement disallowed:” this indicates that the cell belongs to the “shelf placement disallowed area” described above and placing a shelf  51  in the cell is disallowed; and
 
“Non-travelable:” this indicates that the transport vehicle  2  is unable to travel in the cell, for example, because an article has fallen (spilled) in the cell, or the transport vehicle  2  in failure is parked.
 
     The shelf ID in the shelf ID field  113  is an identifier for uniquely identifying the shelf  51 . 
     The article ID in the article ID field  114  is an identifier for uniquely identifying an article to be stored in the shelf  51 . Those records having a cell state other than the “with shelf” have blanks in the shelf ID field  113  and the article ID field  114 . 
     The remark in the remark field  115  is a kind of memorandum and can be any information. Here, it describes the reason for the cell state indicating “placement disallowed” or “non-travelable.” 
     The records in the map information  31  exist as many as the number of cells. The data transceiver  21  of the transport vehicle control device  1  receives a report  71  (see  FIG. 5C ; to be described later in detail) in real time from the data transceiver  26  of a traveling transport vehicle  2 . Then, the map manager  22  of the transport vehicle control device  1  constantly maintains the map information  31  in the latest state, based on the report  71  received. A field  116  is recorded with date and time of day at the time of the latest update. 
     [Article Information] 
     The article information  32  will be described with reference to  FIG. 5B . The article information  32  is stored with, in association with the article ID stored in the article ID field  121 , an article names in an article name field  122 , a shelf ID in a shelf ID field  123 , a quantity in a quantity field  124 , and a picking time in a picking time field  125 . 
     The article ID in the article ID field  121  indicates an article ID for identifying an article which has been picked (taken out) in the picking area. 
     The article name in the article name field  122  indicates a name of the article picked. 
     The shelf ID in the shelf ID field  123  indicates a shelf ID for identifying the shelf  51  which has kept the article picked in the picking area. 
     The quantity in the quantity field  124  indicates a quantity of the articles picked. The unit depends on the article. If the article is a part, for example, the unit is “the number of parts.” The quantity may have a positive or negative sign. If the quantity has a negative value, it indicates that the normal picking (take out) has been made. If the quantity has a positive value, it indicates that the article is replenished. 
     The picking time in the picking time field  125  can be one of the following two types: 
     Type 1) sometime in the future: if there is a plan of picking sometime in the future based on such as a plan of shipping an article or articles from the warehouse, the picking time indicates a date and time of day in the future; the picking time is underscored in this case;
 
Type 2) sometime in the past: if a worker has actually made picking in the picking area, the picking time indicates a date and time of day at that time; and the picking time is not underscored in this case.
 
     For a record of the article information  32 , a record of type 1 is first created, and then a record of type 2 is created every time actual picking is made and stored as article information  32 . Normally, the transport vehicle control device  1  receives records of type 1 and type 2 created by another device which manages picking. However, the transport vehicle control device  1  may create a record of type 2 based on data obtained from the transport vehicle  2 . 
     [Report] 
     A report  71  will be described with reference to  FIG. 5C . The data transceiver  26  of the transport vehicle  2  transmits the report  71  to the transport vehicle control device  1 . The data transceiver  21  of the transport vehicle control unit  1  receives the report  71 . The data transceiver  26  of the transport vehicle  2  transmits one report  71  every time it passes through a cell, while the transport vehicle  2  is traveling, regardless of whether any operation such as “shelf lifted” is performed in the cell. The report  71  for each transmission includes a transport vehicle ID  71   a , a cell ID  71   b , a cell state  71   c , a cargo state  71   d , an operation  71   e , and a transmission time  71   f.    
     The transport vehicle ID  71   a  is an identifier for uniquely identifying the transport vehicle  2 . 
     The cell ID  71   b  is a cell ID for identifying a cell through which the transport vehicle  2  has passed. The transport vehicle  2 , such as by the sensor  43  receiving a radio wave transmitted from the floor or ceiling of the cell, obtains the cell ID included in the radio wave. 
     The cell state  71   c  indicates one of the four states of the cell, as described above, through which the transport vehicle  2  has traveled. However, “with shelf” and “no shelf” are based on a state at the time of departure from the cell. For example, if the transport vehicle  2  has departed after lifting the shelf  51 , the cell state  71   c  indicates “no shelf.” 
     The cargo state  71   d  indicates either an “unloaded vehicle” or a “loaded vehicle.” However, the indication is based on a state at the time of departure from the cell. For example, if the transport vehicle  2  has departed in a state of lifting the shelf  51 , the cargo state  71   d  indicates the “loaded vehicle.” 
     The operation  71   e  indicates an operation of the transport vehicle  2 , including at least five operations below; 
     “Shelf lifted:” this indicates that the shelf support table  62  of the transport vehicle  2  has lifted the shelf  51 ; note that the operation and the shelf ID of the shelf  51  operated may be indicated together such as “shelf lifted, T001;” in addition, the article ID of the article stored in the shelf  51  may also be indicated together such as “shelf lifted, T001, P001” (the same applies to “shelf placed” which immediately follows);
 
“Shelf placed:” this indicates that the shelf support table  62  of the transport vehicle  2  has left the shelf  51  to place the shelf  51  on the floor;
 
“Obstacle detected:” this indicates that the sensor  43  of the transport vehicle  2  has detected a presence of something (fallen article or the like) which inhibits the transport vehicle  2  from traveling through the cell;
 
“Failure:” this indicates that the transport vehicle  2  has failed and has been stuck in that cell; and
 
“−:” this indicates that the transport vehicle  2  has not made any particular operation in the cell.
 
     The transmission time  71   f  indicates a date and time of day at the time of the report  71  being transmitted. 
     [Relationship Among Cell State, Cargo State, and Operation] 
     The transport vehicle  2  having a cargo state of “unloaded vehicle” may transmit either a cell state of “no shelf” (simply passing through with no shelf loaded) or “with shelf” (departing after placing the shelf  51 ). Of course, the transport vehicle  2  having a cargo state of “loaded vehicle” only transmits a cell state of “no shelf” (departing after lifting the shelf  51 ). If the operation indicates “shelf placed,” the cell state always indicates “with shelf.” If the operation indicates “shelf lifted,” the cell state always indicates “no shelf.” The cargo state indicates the “loaded vehicle” during a period from the operation of “shelf lifted” to the operation of “shelf placed.” In other periods, the cargo state indicates the “unloaded vehicle.” [Route Information] 
     The route information  33  will be described with reference to  FIG. 6A . The route information  33  is stored with, in association with an instruction ID stored in an instruction ID field  131 , the transport vehicle ID in a transport vehicle ID field  132 , an instruction in an instruction field  133 , and the transmission time in a transmission time field  134 . 
     The instruction ID in the instruction ID field  131  indicates an identifier for uniquely identifying a record of the route information  33 . 
     The transport vehicle ID in the transport vehicle ID field  132  indicates a transport vehicle ID for identifying the transport vehicle  2  that receives an instruction (to be described immediately below) from the transport vehicle control device  1 . 
     The transmission time in the transmission time field  134  indicates a date and time of day at the time of the instruction being transmitted. 
     The instruction in the instruction field  133  is information indicating a combination of an “instruction route” and an “instruction operation.” In general, there can be two or more candidates for a route from one cell as a start point to the other cell as an end point. Individual routes can be represented by arranging the cells for the transport vehicle  2  to travel in order of traveling. The route searcher  23  determines a route having the shortest travel distance among the two or more candidates as the “instruction route.” The instruction operation is an operation that is transmitted (instructed) by the route searcher  23  of the transport vehicle control device  1  to the transport vehicle  2 . Hereinbelow, the instruction route is simply referred to as the “route” and the instruction operation is simply referred to as the “operation”, as far as there is no risk of misunderstanding. 
     [Specific Example of Instruction] 
     Specific examples of the instruction will be described with reference to  FIG. 6B . Movement of the transport vehicle  2  (represented by a circle) within an oval  72  corresponds to an instruction “(15, 2), (15, 3), [3, 3], (3, 2), (11, 2), &lt;11, 3&gt;, (15, 3), (15, 2)” of a record in the first row shown in  FIG. 6A . Numbers in parentheses indicate the row and column of the cell, respectively. Therefore, two or more brackets in a row indicate the “instruction route.” Among the brackets, [ ] and &lt; &gt; indicate operations to be performed in the respective cells by the transport vehicle  2 . 
     1) The first “(15, 2)” indicates that the transport vehicle  2  starts travelling at the cell “R1502” (cell at the fifteenth row and at the second column; the same applies to others). 
     2) The next “(15, 3)” indicates that the transport vehicle  2  then travels to the cell “R1503.” 
     3) The next “[3, 3]” indicates that the transport vehicle  2  then travels to the cell “R0303,” and parks in the cell to lift the shelf  51  placed in the cell. Note that the transport vehicle  2  is indicated as the “unloaded vehicle” until arriving to the cell “R0303.” This allows the transport vehicle  2  to travel through the cells having a cell state of “with shelf,” such as “R0803.” Then, after departing from the cell “R0303,” the transport vehicle  2  is indicated as the “loaded vehicle.” This inhibits the transport vehicles  2  from traveling through the cells having a cell state of “with shelf,” such as “R0403.” 
     4) The next “(3, 2)” indicates that the transport vehicle  2  then travels to the cell “R0302.” 
     5) The next “(11, 2)” indicates that the transport vehicle  2  then travels to the cell “R1102.” 
     6) The next “&lt;11, 3&gt;” indicates that transport vehicle  2  then travels to the cell “R1103,” and parks in the cell to place the shelf  51 , which has been transported thereto, on the floor of the cell. Note that the transport vehicle  2  is again indicated as the “unloaded vehicle” after departing from the cell “R0303.” This allows the transport vehicle  2  to travel through even the cells having a cell state of “with shelf.” 
     7) The next “(15, 3)” indicates that the transport vehicle  2  then travels to the cell “R1503.” 
     8) The last “(15, 2)” indicates that the transport vehicle  2  completes traveling at the cell “R1502” as the end point. 
     In the movement within the oval  72 , the transport vehicle  2  has departed from the transport-vehicle waiting area, has transported the shelf  51  placed in the cell “R0303” to the cell “R1103,” and then has returned to the transport-vehicle waiting area, as a prerequisite for the worker to make picking in the picking area. The cell state of the cell “R0303” has changed from “with shelf” to “no shelf.” The cell state of the cell “R1103” has changed from “no shelf” to “with shelf.” 
     Similarly, movement of the transport vehicle  2  within an oval  73  corresponds to an instruction “(14, 9), (8, 9), [8, 8], ((11, 8)), &lt;8, 8&gt;, (14, 8), (14, 9)” of a record in the second row shown in  FIG. 6A . Similar description will be omitted, and “((11, 8))” indicates that the transport vehicle  2  parks in the cell “R1108” and waits while the worker is working. In the movement within the oval  73 , the transport vehicle  2  has departed from the transport-vehicle waiting area, and has transported the shelf  51  placed in the cell “R0808” to the cell “R1108,” as a prerequisite for the worker to do tagging in a working area. In addition, after the tagging is completed, the transport vehicle  2  returns the shelf  51  into the cell “R0808,” and then returns to the transport-vehicle waiting area. The cell state of the cell “R0808” has changed from “with shelf” to “no shelf,” and then to “with shelf.” The cell state of the cell “R1108” has changed from “no shelf” to “with shelf,” and then to “no shelf.” 
     [Communication Between Transport Vehicle Control Device and Two or More Transport Vehicles] 
     Communication between the transport vehicle control device  1  and two or more transport vehicles  2  will be described with reference to  FIG. 7 . In  FIG. 7 , the time passes downward from the top of the drawing. It is assumed that two transport vehicles  2  are currently traveling. They have the transport vehicle IDs of “C01” and “C02.” The transport vehicle control device  1  is in communication with “C01” as well as “C02.” 
     Reference numerals  81   a ,  81   b ,  81   c , and  81   d  constitutes a set of processing. The transport vehicle control device  1  transmits an instruction  81   a  to the transport vehicle “C01.” It is assumed, for example, that the instruction includes “[4, 6].” Accordingly, the transport vehicle “C01” lifts a certain shelf  51  in the cell “R0406.” This is an operation  81   b . After that, the transport vehicle “C01” transmits a report  81   c  (having the same data format as the report  71  in  FIG. 5C ) to the transport vehicle control device  1 . Then, the transport vehicle control device  1  updates the cell state of the record for the cell “R0406” in the map information  31  (see  FIG. 5A ) from “with shelf” to “no shelf.” Based on the map information  31  updated, the transport vehicle control device  1  searches for a route through which the other transport vehicle “C02” travels. Of course, the search takes the update result from “with shelf” to “no shelf” into account. Accordingly, the route through which the transport vehicle “C02” travels is also affected by the update result. 
     Reference numerals  82   a ,  82   b ,  82   c , and  82   d  also constitute a set of processing. In addition, the same is true for subsequent reference numerals  83   a  to  83   d  and  84   a  to  84   d . After all, the map information  31  is updated under the influence of all previous operations by the transport vehicles  2 . 
     1) A map information update  81   d  comes from an operation  81   b  by the transport vehicle “C01.” Accordingly, an instruction  83   a  is not changed to something different with respect to the instructions  81   a  for the reason of having the map information update  81   d . This is because the transport vehicle control device  1  is aware of the operation  81   b  at the time of transmitting the instruction  81   a.    
     2) A map information update  82   d  comes from an operation  82   b  by the transport vehicle “C02.” Accordingly, an indication  83   a  may be changed with respect to the instruction  81   a  for the reason of having the map information update  82   d . In this case, as the operation  82   b  is “shelf lifted,” a route to be included in the instruction  83   a  is likely to be shorter than the route that has been included in the instruction  81   a . This is because a route for the transport vehicle “C01” has been searched on the condition that the cell where the operation  82   b  of “shelf lifted” is made remains to have the shelf  51 , but now a route can be searched again on a less restricted condition that the cell has no shelf  51 . 
     3) A map information updating  83   d  comes from an operation  83   b  by the transport vehicle “C01.” Accordingly, an instruction  84   a  may be changed with respect to the instruction  82   a  for the reason of having the map information update  83   d . In this case, as the operation  83   b  is “shelf placed,” a route to be included in the instruction  84   a  is likely to be longer than the route that has been included in the instruction  82   a . This is because the transport vehicle “C01” has placed the shelf  51  in the cell through which the transport vehicle “C02” is planned to travel, a route need to be searched again on a more restricted condition which is contrary to 2) above. 
     The same holds true even when the transport vehicle “C01” is interchanged with the transport vehicle “C02.” 
     [Operation Procedures] 
     Hereinbelow, operation procedures of the present embodiment will be described. There are three operation procedures. The first one is a “map information update procedure” in which the transport vehicle control device  1  updates the map information  31  every time upon receiving the report  71  from the transport vehicle  2 . The second one is a “cell-for-rearranged-shelf determination procedure” in which cells to be arranged with the shelves  51  are revised depending on the picking frequency. The third one is a “shelf rearrangement procedure” in which the shelves  51  are actually moved to the revised cells. 
     [Map Information Update Procedure] 
     The map information update procedure will be described with reference to  FIG. 8 . 
     In step S 301 , the data transceiver  21  of the transport vehicle control device  1  determines whether it has received any report  71 . Specifically, if the data transceiver  21  has received a report  71  (see  FIG. 5C ), which indicates that a state of a cell has been changed, from any of the transport vehicles  2  (“YES” in step S 301 ), the process proceeds to step S 302 . If the data transceiver  21  has not received any report  71  (“NO” in step S 301 ), the data transceiver  21  waits until it receives a report  71 . A report  71  such as only indicating that the transport vehicle  2  has passed through the cell is ignored. 
     In step S 302 , the map manager  22  of the transport vehicle control device  1  identifies cells having a state changed. Now, it is assumed that the map information  31  is in a state as shown in  FIG. 5A . It is also assumed that the cell ID included in the received report  71  is “R0303,” a cell state is “no shelf,” a cargo state is “loaded vehicle,” and the operation is “shelf lifted, T001, P001.” Then, the cell state of “with shelf” on the sixth row in  FIG. 5A  is different from the cell state of “no shelf” included in the report  71 . In this case, the map manager  22  identifies the cell “R0303” as the cell having a state changed. Note that the identified cell of “R0303” is called an “identified cell,” and the record of the map information  31  for the identified cell is also referred to as a “candidate-for-change map information record.” 
     In step S 303 , the map manager  22  determines whether there is any transport vehicle  2  which is planned to travel through the identified cell. Specifically, the map manager  22  determines whether there is any record in the route information  33  (see  FIG. 6A ) which satisfies all of the following conditions. Such a record is also referred to as a “candidate-for-change route information record.”
         The transmission time falls between the present time and a predetermined period of time (e.g., one minute) earlier; and   The route contained in the instruction includes the “identified cell.”       

     If there is any candidate-for-change route information record (“YES” in step S 303 ) as a result of the determination, the map manager  22  temporarily stores all the candidate-for-change route information records in the main memory  14 , and proceeds to step S 304 . If there is no candidate-for-change route information record (“NO” in step S 303 ), the map information update procedure ends. 
     In step S 304 , the map manager  22  determines whether the change causes the cell state to be “non-travelable.” Specifically, if the cell information in the candidate-for-change map information record is other than “non-travelable” and the cell state in the report  71  received is “non-travelable” (“YES” in step S 304 ), the map manager  22  proceeds to step S 306 . Otherwise (“NO” in step S 304 ), the map manager  22  proceeds to step S 305 . 
     In step S 305 , the map manager  22  determines whether the change causes the cell state to be “no shelf.” Specifically, if the cell information in the candidate-for-change map information record is “with shelf” and the cell state of the report  71  received is “no shelf” (“YES” in step S 305 ), the map manager  22  proceeds to step S 307 . Otherwise (“NO” in step S 305 ), the map manager  22  proceeds to step S 306 . 
     In step S 306 , the map manager  22  determines to hold a change of the cell state. Specifically, the map manager  22  determines not to change the candidate-for-change map information record. After that, the map manager  22  returns to step S 301 . 
     In step S 307 , the map manager  22  determines that the cell state can be changed. Specifically, the map manager  22  determines to change the candidate-for-change map information record. 
     In step S 308 , the map manager  22  updates the map information  31 . Specifically, the map manager  22  updates the cell state of the candidate-for-change map information record with the cell information included in the report  71  received. 
     In step S 309 , the route searcher  23  in the transport vehicle control device  1  searches for a route. 
     Specifically, the route searcher  23  first obtains one candidate-for-change route information record which is not processed yet. In this case, it is assumed, for example, that the record in the first row in  FIG. 6A  is obtained. 
     Second, the route searcher  23  obtains the starting point, transit points, and the end point of the obtained record. In this example, the starting point of “(15, 2),” the transit points of “[3, 3]” and “&lt;11, 3&gt;”, and the end point of “(15, 2)” are obtained. The transit point is a cell where the transport vehicle  2  operates “shelf lifted” or “shelf placed.” 
     Third, the route searcher  23  obtains the shortest route as the instruction route among the routes satisfying all of the following conditions. Here, the route searcher  23  may use an existing search technology such as Dijkstra&#39;s algorithm.
         The route runs through the starting point, the transit point of “shelf lifted,” the transit point of “shelf placed,” and the end point obtained in the second portion of step S 309  in this order;   The route does not include a cell having a cell state of “non-travelable” in the latest map information  31 ; and   The route does not include a cell having a cell state of “with shelf” in the latest map information  31  between the transit point of “shelf lifted” and the transit point of “shelf placed.”       

     Fourth, the route searcher  23  creates a new record of the route information  33  to store the transport vehicle ID of the candidate-for-change route information record into the transport vehicle ID field  132  of the record created. Then, the route searcher  23  stores the instruction ID that has newly been numbered into the instruction field  131 , and the present time into the transmission time field  134 . In addition, the route searcher  23  creates an instruction based on the instruction route obtained in the third portion of step S 309  to store into the instruction field  133 . The instruction to be stored at this time includes transit points of “[3, 3]” and “&lt;11, 3&gt;.” 
     Fifth, the route searcher  23  designs the instruction stored in the instruction field  133  to display on the output device  15  of the transport vehicle control device  1 . The route searcher  23  separately displays the designs, such as the oval  72  in  FIG. 6B , one before and the other after the update. 
     In step S 310 , the data transceiver  21  of the transport vehicle control device  1  transmits an instruction route. Specifically, the data transceiver  21  transmits the instruction record created in the fourth portion of step S 309  to the transport vehicle  2  which is identified in the transport vehicle ID of the candidate-for-change route information record. After that, the map information update procedure is completed. 
     Note that the processing in steps S 309  and S 310  is repeated until there is no more candidate-for-change route information record which is not processed yet. 
     [Modification of Map Information Update Procedure] 
     The user can set a path that leads to processing in step S 306  or S 307  in any way. In the example described above, if a cell is changed to have a state of “no shelf” to make a condition of searching for a route less restricted (having a possibility of newly finding a shorter route), the processing proceeds to step S 307 . After that, the map information  31  is updated to search for a route, according to the setting. However, “YES” and “NO” in step S 305  may be reversed, for example, and if a cell is changed to make a condition of searching for a route harder (having to give up the shortest path, but collision of the shelf  51  being preventable), the processing may proceed to step S 307 . 
     In the example described above, the transport vehicle  2  in failure is assumed to be restored soon. In addition, it is assumed that even if there is an obstacle in a cell, it is immediately cleared by a worker or another system. However, if safety is intended to have a higher priority than improving transportation efficiency or shortening a transportation time, the processing may proceed to step S 307 , for example, immediately after “YES” in step S 304 . In this case, the data transceiver  21  of the transport vehicle control device  1  may transmit an instruction to the effect of immediately making an emergency stop to the transport vehicles  2  which are specified in the transport vehicle IDs of all candidate-for-change route information records. Alternatively, the data transceiver  21  may transmit an instruction to the effect of continuing the travel for a while and then stopping in a cell just before the cell having a cell state of “non-travelable.” 
     In the example described above, the process is completed if there is no transport vehicle  2  that is planned to travel through the cell. However, the process may proceed to step S 307  immediately after “YES” in step S 303 , and further to step S 308  immediately thereafter, before the processing is completed. In this way, the map information is updated. Therefore, this is effective if there is a transport vehicle  2  that is newly planned to travel through the cell. 
     [Cell-for-Rearranged-Shelf Determination Procedure] 
     The cell-for-rearranged-shelf determination procedure will be described with reference to  FIG. 9A . 
     In step S 321 , the cell-for-rearranged-shelf determiner  24  of the transport vehicle control device  1  determines whether picking has been completed. Specifically, the cell-for-rearranged-shelf determiner  24  proceeds to step S 322  if a type 2 record of the article information  32  (see  FIG. 5B ) is created (“YES” in step S 321 ). Otherwise (“NO” in step S 321 ), the cell-for-rearranged-shelf determiner  24  waits until a type 2 record is created. 
     In step S 322 , the cell-for-rearranged-shelf determiner  24  arranges the shelves according to the picking frequency. More specifically, the cell-for-rearranged-shelf determiner  24  first obtains records, which satisfy all of the following conditions, from the article information  32  (see  FIG. 5B ).
         It is a type 2 record; and   The picking time falls between the present time and a predetermined period of time (e.g., one week) earlier.       

     Second, the cell-for-rearranged-shelf determiner  24  sorts records obtained in the first portion of step S 322  by shelf ID, and obtains the number of records for each shelf ID. Then, data such as “(shelf ID, the number of records)=(T001, 50), (T002, 70), (T003, 40), (T004, 60), - - - ” is obtained. 
     Third, the cell-for-rearranged-shelf determiner  24  rearranges the shelf IDs in descending order of the number of records. In this example, the shelf IDs are rearranged so as to be “T002, T004, T001, T003, - - - .” 
     In step S 323 , the cell-for-rearranged-shelf determiner  24  arranges the cells according to the distance from the picking area. Specifically, the cell-for-rearranged-shelf determiner  24  first obtains records, which satisfy all of the following conditions, from the map information  31  (see  FIG. 5A ).
         The cell state is “no shelf.”   The cell identified in the cell ID does not match one in “&lt; &gt;” which is included in the instruction of the record of the route information  33  (see  FIG. 6A ). Here, the record of the route information  33  is limited to one having the transmission time which falls between the present time and a predetermined period of time (e.g., one minute) earlier.   The cell is located in the provisional storage area described above (see  FIG. 3 ). The provisional storage area has a short enough distance from the picking area. Note that this condition is not essential.       

     Second, the cell-for-rearranged-shelf determiner  24  rearranges the cell IDs of the records obtained in the first portion of step S 323  in ascending order of the distance between the picking area and the cell. The distance here is one which the transport vehicle  2  travels between the cell and the picking area (not the inclined straight-line distance). As a result, the cell IDs are rearranged such as “R0804, R0603, R0507, R0308, - - - .” 
     In step S 324 , the cell-for-rearranged-shelf determiner  24  assigns a cell for rearrangement to each shelf. Specifically, the shelves rearranged in the third portion of step S 322  are associated with the cells rearranged in the second portion of step S 323 . As a result, data such as “(shelf ID, cell ID)=(T002, R0804), (T004, R0603), (T001, R0507), (T003, R0308), - - - ” is obtained. 
     The cell-for-rearranged-shelf determiner  24  stores the obtained data in the auxiliary storage device  15 , and then ends the cell-for-rearranged-shelf determination procedure. 
     The route searcher  23  of the transport vehicle control device  1  searches for a route through which the transport vehicle  2  moves a shelf  51  based on the data obtained in step S 324 . For example, a route for moving the shelf “T002” from the cell where the shelf is currently located to the cell “R0804” is searched. The actual movement may be made, for example, on its way returning from the picking area. 
     Note that, if the cell for rearrangement is determined to be in the provisional storage area, the cell-for-rearranged-shelf determiner  24  measures a time for the shelf  51  to continuously sit in the provisional storage area. Then, if the time exceeds a predetermined threshold value, the shelf  51  is determined to be transported to a cell outside the provisional storage area. 
     [Modifications of Cell-for-Rearranged-Shelf Determination Procedure] 
     In the second portion of step S 322 , the cell-for-rearranged-shelf determiner  24  may obtain the sum of the absolute values of the quantities for each shelf ID, instead of the number of records. 
     In the first portion of step S 322 , the cell-for-rearranged-shelf determiner  24  may use a condition of “i) it is a type 1 record” instead of being the type 2 record. In addition, a condition of “ii) it is a type 1 record, and the picking time has a date of the present time (current day)” may be used. Further, in the case of ii), the cell-for-rearranged-shelf determiner  24  may rearrange the shelf IDs, in the third portion of step S 322 , in descending order of “a ratio of the absolute value of quantity on the current day to the total number of articles stored on the shelf.” 
     [Shelf Rearrangement Procedure] 
     Prior to describing  FIG. 9B , assumptions will be described for the shelf rearrangement procedure with reference to  FIGS. 10A-10C .  FIG. 10A  shows shelves  51  arranged before shelf rearrangement. The shelf “T101” need to be transported, for such a reason as the frequency of being transported to the picking area is high, to a cell which has a shorter distance from the picking area than the current cell. However, the shelf “T101” is in a state of being surrounded by other shelves. In this case, in order to secure a route to the cell where the shelf “T101” is to be rearranged, the transport vehicle  2  provisionally moves the other shelf “T102” (see  FIG. 10B ). Next, the transport vehicle  2  actually moves the shelf “T101” to the cell for rearrangement (see  FIG. 10C ). In addition, the transport vehicle  2  moves the shelf “T102,” which has been provisionally moved, back to the original cell. In this example, the shelf “T101” is referred to as a “shelf to be rearranged” and the shelf “T102” is referred to as a “shelf to be provisionally moved.” The cell for rearranging the shelf to be rearranged is referred to as a “destined cell.” 
     Referring back to  FIG. 9B , the shelf rearrangement procedure will be described. 
     In step S 331 , the transport vehicle control device  1  determines the shelf to be provisionally moved. Specifically, the route searcher  23  of the transport vehicle control device  1  first obtains the shortest route for the transport vehicle  2  transporting the shelf to be rearranged from the cell where the shelf is now located to the destined cell. At this time, the route searcher  23  searches for a route on the assumption that the cells having all the shelves which the shelf to be rearranged must come across before exiting to any passage outside the block will have a state of “no shelf.” In  FIG. 10A , the shelf “T101” is the shelf to be rearranged. Accordingly, all the shelves which the shelf “T101” must come across before exiting to any passage are five shelves (denoted by “*”) at the left and right sides and at the upper and lower sides within the block, inclusive of the shelf “T102.” 
     Second, the shelf rearranger  25  of the transport vehicle control device  1  identifies the shelves on the route obtained in the first portion of step S 331  as the shelves to be provisionally moved. Now, it is assumed that the route obtained in the first portion of step S 331  is a route  92  in  FIG. 10C . Then, the shelf rearranger  25  identifies the shelf “T102” as the shelf to be provisionally moved. Two or more shelves to be provisionally moved may exist in some cases. 
     In step S 332 , the shelf rearranger  25  determines a sequence of provisional movement. Specifically, the shelf rearranger  25  determines a sequence of the shelves to be provisionally moved, which have been identified in the second portion of step S 331 , in ascending order of the distance between the cell where the shelf is currently located and the destined cell. In the example in  FIG. 10A , there is only one shelf to be provisionally moved (i.e., shelf “T102”). However, there may be two shelves to be provisionally moved (denoted by “#”) in some case. In this case, one shelf closer to a passage is determined to have a sequence number of “1” and the other shelf to have a sequence number of “2.” This sequence is referred to as a sequence of provisional movement. 
     In step S 333 , the shelf rearranger  25  determines a cell for provisional movement. Specifically, the shelf rearranger  25  determines any cell which is not on the route  92  (see  FIG. 10C ) as a cell for provisional movement. The shelf rearranger  25  specifies in advance a sufficient number of consecutive cells as “buffer cells” (see  FIG. 10B ), and if there are two or more shelves to be provisionally moved, the buffer cells in descending order of the distance from the destined cells are sequentially assigned (from right to left) to the shelves having a smaller sequence number of provisional movement (earlier timing of movement) as the cells for provisional movement. 
     In step S 334 , the route searcher  23  searches for a route. Specifically, the route searcher  23  first obtains the shortest route  91  (see  FIG. 10 ) for the transport vehicle  2  transporting the shelf to be provisionally moved, having the smallest sequence number of provisional movement, to the buffer cell. 
     Second, the route searcher  23  obtains the shortest route for the transport vehicle  2  transporting the shelf to be provisionally moved, having the next smallest sequence number of provisional movement, to the buffer cell. Then, the same processing is repeated as many times as the number of shelves to be provisionally moved. 
     In step S 335 , the shelf rearranger  25  assigns the transport vehicles  2 . Specifically, the shelf rearranger  25  assigns the transport vehicles  2  to the shelves to be provisionally moved, respectively, for transporting the shelves. The shelf rearranger  25  assigns the transport vehicles  2  which are located in the closest cells from the cells where respective shelves to be provisionally moved are located. In this case, the transport vehicles  2  are required as many as the number of the shelves to be provisionally moved. The shelf rearranger  25  may repeatedly use a particular or any transport vehicle  2  to transport all the shelves to be provisionally moved. 
     In step S 336 , the data transceiver  21  of the transport vehicle control device  1  transmits an instruction route. Specifically, the data transceiver  21  transmits an instruction to the transport vehicle  2  assigned in step S 335 . The instruction includes the route obtained in step S 334  as the instruction route, and an instruction operation for transporting the shelf to be provisionally moved from the current cell to the buffer cell. 
     In step S 337 , the shelf rearranger  25  returns the shelves to be provisionally moved. Specifically, the shelf rearranger  25  transports the shelves to be provisionally moved to the original cells, in descending order of the sequence number of provisional movement. The processing is made in reverse order of the processing in steps S 334  to S 336  described above. 
     Advantageous Effects of Present Embodiment 
     The transport vehicle control device of the present embodiment has following advantageous effects: 
     1) A route through which a transport vehicle is traveling is revised in real time, according to reports from the transport vehicles on a state of the cells, and the revised results are viewable on the screen;
 
2) Those shelves that store articles which are frequently picked are transported closer to the picking area;
 
3) A determination is made, depending on the changed state of the cell, whether the map information is updated immediately or later at the next reporting time;
 
4) A shelf which has been sitting in the provisional storage area for a certain period of time is transported outside the area to allow the shelf storing articles, which are frequently picked at the present time, to be surely transported to the provisional storage area;
 
5) A shelf is rearranged even when the shelf is surrounded by other shelves;
 
6) A state of the cell is one of “with shelf,” “no shelf,” or “non-travelable,” and is easily identified by the transport vehicle;
 
7) A timing of updating the map is flexibly determined for a case where the cell state has been changed from “with shelf” to “no shelf;” and
 
8) A timing of updating the map is flexibly determined for a case where the cell state has become “non-travelable.”
 
     Note that the present invention is not limited to the embodiment described above, and includes various modifications. For example, the embodiment hereinabove is described in detail in order to illustrate the present invention, and is not necessarily limited to include the entire configuration as described. A part of the configuration of an embodiment may be replaced by the configuration of another embodiment, and/or the configuration of an embodiment may be added with the configuration of another embodiment. In addition, a part of the configuration of each embodiment may be removed, or added with and/or replaced by another configuration. 
     Further, each configuration, function, processing portion, and/or processing means described above may be implemented in part or entirely by hardware such as an integrated circuit. Each configuration and/or function described above may be implemented by software by the processor interpreting and executing programs for implementing the respective functions. Information such as program for implementing respective functions, tables, and files can be stored in a recording device such as a memory, a hard disk, and a Solid State Drive (SSD), or a recording medium such as an IC card, an SD card, and a DVD. 
     Furthermore, the control lines and information lines are shown for the purpose of illustration, and all control lines and information lines in the product are not necessarily shown. In fact, it may be safe to say that almost all components are connected with one another.