Patent Publication Number: US-2022229447-A1

Title: Traveling vehicle system and traveling vehicle control method

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a traveling vehicle system, and a traveling vehicle control method. 
     2. Description of the Related Art 
     In a semiconductor device manufacturing factory or the like, a traveling vehicle system is used for purposes such as transporting articles. The traveling vehicle system includes, for example, a plurality of traveling vehicles that travel on a track and a controller that controls the traveling vehicles. In such a traveling vehicle system, in some cases, a traveling range of the traveling vehicles is divided into a plurality of areas and the traveling vehicles in each area are controlled by a controller. Japanese Unexamined Patent Application, First Publication No. 2005-92823 discloses a configuration in which, in the control performed by such a controller, the maximum number of vehicles allowed to be present in a specific area is set preliminarily, and when one traveling vehicle enters the specific area, this traveling vehicle will not be permitted to enter the specific area if the number of other traveling vehicles present in the specific area is greater than or equal to this preliminarily set number of vehicles. 
     SUMMARY OF THE INVENTION 
     In the traveling vehicle system mentioned above, when entry permission requests are made from a plurality of traveling vehicles, entry permission for the specific area is granted to a traveling vehicle that made an entry permission request first. The controller of the traveling vehicle system receives an entry permission request from each traveling vehicle through cyclic communication (polling communication), and the order of entry permission requests being made and the order of the traveling vehicles queuing may be reversed in some cases, depending on the timing of this communication being performed. Therefore, for example, in a case where entry permission is granted to a traveling vehicle that made an entry permission request first in a situation where the number of traveling vehicles present in a specific area is one vehicle less than the maximum number of vehicles, even if a traveling vehicle that is able to enter the specific area first makes an entry permission request later, entry of this traveling vehicle will not be permitted because the maximum number of vehicles of the specific area has already been reached. 
     As a result, the traveling vehicle that cannot obtain entry permission stops and waits just short of the position of entry to the specific area, and if a traveling vehicle that has been granted entry permission approaches from behind the waiting traveling vehicle, traveling thereof will be hindered and stopped by the traveling vehicle that is waiting. The traveling vehicle waiting just short of the position of entry to the specific area remains stopped until entry permission is obtained, and the traveling vehicle behind the traveling vehicle waiting just short of the position of entry, which already has obtained entry permission, remains stopped until the traveling vehicle in front thereof proceeds. This is not desirable because a plurality of traveling vehicles may stop and become stuck on the entry route to the specific area in some cases, and this will result in the reduced utilization rate of the traveling vehicles. 
     Preferred embodiments of the present invention provide traveling vehicle systems and traveling vehicle control methods each capable of preventing a reduction in the utilization rates of traveling vehicles by ensuring smooth entry of the traveling vehicles into an area. 
     A traveling vehicle system according to an aspect of a preferred embodiment of the present invention is a traveling vehicle system including a track sectioned into a plurality of areas, a plurality of traveling vehicles to travel on the track, and a controller to control, in each of the plurality of areas, the traveling vehicles within the area, wherein the controller is configured or programmed to include a determiner to determine, upon receiving from one of the plurality of traveling vehicles an entry permission request for an area under control, whether or not a remaining number of vehicles to a maximum number of vehicles allowed to enter the area is equal to or less than a predetermined number, and an entry permitter to temporarily hold the entry permission request from the traveling vehicle if the determiner determines the predetermined number has not been exceeded, and upon arrival of the traveling vehicle of a transmission origin of the entry permission request at an entry region for the area, grant the traveling vehicle permission to enter the area if a sum of a number of traveling vehicles present within an area of an entry target and a number of traveling vehicles already permitted to enter the area is less than a maximum number of vehicles, but does not grant entry permission if the sum has reached the maximum number of vehicles. 
     If the determiner determines the remaining number of vehicles as being greater than the predetermined number, the entry permitter may grant the traveling vehicles entry permission to the area based on an order of receipt of the entry permission requests. The entry permitter may grant entry permission to the traveling vehicle that stops first at an entry point in the entry region, among the traveling vehicles from which the entry permission requests have been received. The entry region may have a length in the traveling direction of the traveling vehicle that prevents another traveling vehicle from entering thereto when one traveling vehicle is located therein. A plurality of the entry regions may be provided for one of the areas, and the entry permitter may grant entry permission to one traveling vehicle that arrives first at any one of a plurality of the entry regions. The determiner may be able to change the predetermined number. 
     A traveling vehicle control method according to an aspect of a preferred embodiment of the present invention is a method for controlling a plurality of traveling vehicles traveling on a track sectioned into a plurality of areas, the method including determining, upon receiving from one of the plurality of traveling vehicles an entry permission request for an area under control, whether or not a remaining number of vehicles to a maximum number of vehicles allowed to enter the area is equal to or less than a predetermined number, and if the predetermined number is determined as not having been exceeded, temporarily holding the entry permission request from the traveling vehicle and granting entry permission to one traveling vehicle that arrives first at an entry region for the area. 
     According to the traveling vehicle system and the traveling vehicle control method of the above aspects of preferred embodiments of the present invention, when an entry permission request for an area is received from a traveling vehicle, if the remaining number of vehicles to the maximum number of vehicles allowed to enter the area is equal to or less than a predetermined number, the entry permission request from the traveling vehicle is temporarily held, and entry permission is granted to one traveling vehicle that arrives first at an entry region for the area. As a result, a traveling vehicle that has not arrived at the entry region will not be granted entry permission even if it has requested entry permission. Therefore, entry permission is granted to the traveling vehicle that arrives first at the entry region regardless of the order of entry permission requests having been made, and as a result, it is possible to avoid a plurality of traveling vehicles from stopping and becoming stuck on an entry route into the area, and it is possible to ensure smooth entry of traveling vehicles into the area and prevent a reduction in the utilization rate of the traveling vehicles. 
     If the determiner determines the remaining number of vehicles is greater than the predetermined number, the entry permitter grants the traveling vehicles entry permission to the area in the order of receipt of the entry permission requests, when the remaining number of vehicles to the maximum number of vehicles allowed to enter the area is ample. Thus, it is possible to perform smooth entry of traveling vehicles into the area while reducing the load on the controller, by granting entry permission to the traveling vehicles in the order of receipt of entry permission requests without temporarily holding the entry permission requests from the traveling vehicles. 
     Also, as a result of the entry permitter granting entry permission to the traveling vehicle that stops first at an entry point in the entry region, among the traveling vehicles from which entry permission requests have been received, it is possible to appropriately grant entry permission to the traveling vehicle in a stop state at the entry point from which earliest entry to the area is possible. For example, even in a case where traveling vehicles enter the plurality of entry regions respectively at almost the same time, it is possible to grant entry permission to the traveling vehicle that stops first at the entry point. 
     The entry region may have a length in the traveling direction of the traveling vehicle that prevents another traveling vehicle from entering thereto when one traveling vehicle is located therein. As a result, only one traveling vehicle can enter the entry region, which prevents multiple traveling vehicles from entering the entry region, and it is therefore possible to reliably grant entry permission to one traveling vehicle that is already present (arrives first) at the entry region. 
     A plurality of the entry regions may be provided for one area, and the entry permitter may grant entry permission to one traveling vehicle that arrives first at any one of a plurality of the entry regions. Thus, even in a case where a plurality of entry regions are provided for one area, it is possible to perform smooth entry of traveling vehicles into the area by granting entry permission to a traveling vehicle that arrives first at any of the entry regions. 
     The determiner may be able to change the predetermined number, such that it is possible to perform smooth entry of traveling vehicles into the area by setting the predetermined number according to the operating status of the traveling vehicles in the area. 
     The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an example of a traveling vehicle system according to a preferred embodiment of the present invention. 
         FIG. 2  is a diagram showing an example of a functional block configuration of a controller and a traveling vehicle. 
         FIG. 3  is a flowchart showing an example of a traveling vehicle control method according to a preferred embodiment of the present invention. 
         FIG. 4  is a flowchart showing an example of a detailed process flow of Step S 11  in  FIG. 3 . 
         FIG. 5  is a diagram showing an example of operations of the traveling vehicles in the traveling vehicle system. 
         FIG. 6  is a diagram showing another example of the operations of the traveling vehicles in the traveling vehicle system. 
         FIG. 7  is a diagram showing still another example of the operations of the traveling vehicles in the traveling vehicle system. 
         FIG. 8  is a diagram showing still another example of the operations of the traveling vehicles in the traveling vehicle system. 
         FIG. 9  is a diagram showing still another example of the operations of the traveling vehicles in the traveling vehicle system. 
         FIG. 10  is a diagram showing still another example of the operations of the traveling vehicles in the traveling vehicle system. 
         FIG. 11  is a diagram showing still another example of the operations of the traveling vehicles in the traveling vehicle system. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following describes preferred embodiments of the present invention with reference to the drawings. However, the present invention is not limited to the preferred embodiments. In the drawings, scale is changed as necessary to illustrate the preferred embodiments, such as by enlarging or by emphasizing a portion. 
       FIG. 1  is a diagram showing an example of a traveling vehicle system according to a preferred embodiment of the present invention. A traveling vehicle system SYS according to the present preferred embodiment is a system for transporting articles by using traveling vehicles V, for example, in a building such as a factory or a warehouse. The traveling vehicle system SYS includes, for example, a track TA, a plurality of traveling vehicles V, a host controller MC, and a controller TC. The track TA can be set arbitrarily and may be suspended from the ceiling of a building or installed on the floor surface of the building, for example. 
     The track TA is sectioned into a plurality of areas CA. In the present preferred embodiment, the track TA is sectioned into, for example, four areas, a first area CA 1  to a fourth area CA 4 . In each area CA, there is provided a circular track  11 . The circular track  11  circles around within one of the areas CA. In the present preferred embodiment, the circular track  11  is provided in each area CA, however, the layout, structure, arrangement, and so forth of the track provided in each area CA are not limited in any way and can be set arbitrarily. That is to say, in the area CA, not only the circular track  11  but also a track of various forms, such as a non-circular track, a track branching off the circular track  11 , or a track merging into the circular track  11 , that enables movements of the traveling vehicles V in the area CA may be provided. Also, a circular track that spans across a plurality of areas CA may be provided. 
     Two areas CA adjacent to each other are connected by connection tracks  12 ,  13 . In other words, a traveling vehicle V in an area CA can move to another area CA adjacent to this area CA via the connection tracks  12 ,  13 . Looking at the first area CA 1  as the center, three areas adjacent to the first area CA 1 , the second area CA 2  to the fourth area CA 4 , are each connected to the first area CA 1  via connection tracks  12 ,  13 . Each connection track  12  defines and functions as an entry route when a traveling vehicle V enters the first area CA 1  from another area, such as the second area CA 2  to the fourth area CA 4 . Each connection track  13  defines and functions as an exit route when a traveling vehicle V exits the first area CA 1  to another area, such as the second area CA 2  to the fourth area CA 4 . 
     Each of the plurality of traveling vehicles V travels along a predetermined track TA. Each traveling vehicle V can travel on the circular track  11  of the plurality of areas CA. Each traveling vehicle V can enter the circular track  11  of the adjacent first area CA 1  from the currently traveling circular track  11  of the second area CA 2  to the fourth area CA 4 , via the connection track  12 . Also, each traveling vehicle V can exit to the circular track  11  of the adjacent second area CA 2  to the fourth area CA 4  from the currently traveling circular track  11  of the first area CA 1 , via the connection track  13 . 
     Each traveling vehicle V may be in a form of traveling on the track TA or may be in a form in which the main body thereof is suspended from the track TA, for example, in the case where the track TA is an overhead track. Each traveling vehicle V may be capable of traveling while holding an article and may include a transferer to receive or deliver an article from or to a transfer destination. Each traveling vehicle V is set so as to travel in one direction (travel forward) with respect to the track TA and not to travel in the opposite direction. The traveling vehicle V has, for example, an obstacle sensor mounted thereon and is controlled to stop if an obstacle (for example, another stopped traveling vehicle V) is present in front thereof. 
       FIG. 2  is a diagram showing an example of a functional block configuration of the controller and the traveling vehicle. As shown in  FIG. 2 , each traveling vehicle V includes an in-vehicle controller VC. The in-vehicle controller VC controls the traveling vehicle V according to instructions transmitted from the controller TC. The in-vehicle controller VC controls various operations of the traveling vehicle V (such as traveling, speed control (accelerating, decelerating, and stopping). The in-vehicle controller VC may be a computer system that includes, for example, a CPU, a memory storage device, and a communication device, and performs tasks such as processing of various information, storing information, input and output of information, and communication (transmitting/receiving) of information. 
     The in-vehicle controller VC acquires state information that indicates the state of the traveling vehicle V. The state information of the traveling vehicle V includes, for example, information indicating the current position of the traveling vehicle V (current position information), information on traveling (such as speed and stop state), information on the state (status) of various instructions transmitted from (assigned by) the controller TC described later, and time information indicating the time at which the state of the traveling vehicle V changed (such as the time at which the traveling vehicle V stopped). The state information includes, for example, information indicating completion or failure of execution of operations or processes related to various instructions (such as traveling, transferring). 
     A plurality of indicator markings (not shown in the drawings) provided along the track TA are used in order for the in-vehicle controller VC to obtain current position information indicating the current position of the traveling vehicle V. For each indicator marking, for example, a bar code or the like is used. Each indicator marking is provided at a predetermined position along the track TA. The predetermined position is, for example, a position corresponding to a load port, a storage rack, or the like to which articles are transferred by the traveling vehicle V. The traveling vehicle V reads the indicator marking while traveling, using a bar code reader or the like equipped on the traveling vehicle V, to recognize the position of its own. 
     As shown in  FIG. 1 , in the present preferred embodiment, the controller includes the host controller MC and the controller TC. The host controller MC and the controller TC are connected to communicate with each other via a transmission path such as a wired LAN (Local Area Network) or a wireless LAN. The controller TC and the in-vehicle controller VC are connected to communicate with each other in a wireless manner via a transmission path such as a wireless LAN or feeder communication using a feeder line. 
     The host controller MC provides instructions co control traveling of each traveling vehicle V in the traveling vehicle system SYS. The host controller MC includes, for example, a CPU, a memory storage device, and a communication device, and performs tasks such as processing of various information, storing information, input and output of information, and communication (transmitting/receiving) of information. As the host controller MC, for example, a computer system is used. The host controller MC may be of a configuration in which information on the state of each traveling vehicle V such as a traveling start position PS and traveling end position PE, information on the state of instructions transmitted to the controller TC from the host controller MC, and so forth, are acquired from each element of the system including the controller TC. 
     The host controller MC includes a host traveling instruction generator  31  to generate a host traveling instruction that causes the traveling vehicle V to travel from a predetermined traveling start position PS to a predetermined traveling end position PE. The host traveling instruction includes, for example, traveling start port information indicating a traveling start position PS, traveling end port information indicating a traveling end position PE, and an instruction to cause the traveling vehicle V to travel from the traveling start position PS to the traveling end position PE. The host traveling instruction may be, for example, a transport instruction to transport an article at a traveling start port to a transfer destination defining and functioning as a travel end port. The host controller MC transmits the host traveling instruction generated by the host traveling instruction generator  31  to the controller TC. Having received the host traveling instruction, the controller TC assigns a traveling instruction corresponding to the host traveling instruction to a traveling vehicle V present in the area CA under its own control. The host controller MC may assign a host traveling instruction to a traveling vehicle V to which a traveling instruction has not been assigned yet, among the plurality of traveling vehicles V. 
     The traveling vehicle V travels on the track TA from the traveling start position PS toward the traveling end position PE according to the traveling instruction assigned by the controller TC. The route on which the traveling vehicle V is to travel from the traveling start position PS to the traveling end position PE may be generated by the host controller MC or the controller TC and transmitted to the traveling vehicle V along with the traveling instruction, or the in-vehicle controller VC of the traveling vehicle V may generate the traveling route from preliminarily stored route map information, on the basis of the assigned traveling start position PS and traveling end position PE. 
     The controller TC transmits various instructions to traveling vehicles V located in the area CA under the control thereof to thereby control each of the plurality of traveling vehicles V. The controller TC includes, for example, a CPU, a memory storage device, and a communication device, and performs tasks such as processing of various information, storing information, input and output of information, and communication (transmitting/receiving) of information. As the controller TC, for example, a computer system is used. The controller TC has control over one of the areas CA, and controls traveling vehicles V within one of the areas CA under the control thereof. In such a case, separate controllers TC are arranged respectively in the plurality of areas CA of the track TA. The plurality of controllers TC are connected so as to be able to communicate with each other via a wired or wireless communication line. In such an aspect, entry permission requests from traveling vehicles V, which will be described later, are exchanged (transmitted and/or received) between the plurality of controllers TC. 
     The controller TC may be in a form in which a plurality of controllers each having control over the plurality of areas CA are functionally integrated. In the present preferred embodiment, the controller TC has control over four areas, the first area CA 1  to fourth area CA 4 . The controller TC functionally includes a first controller TC 1  that has control over the first area CA 1 , a second controller TC 2  that has control over the second area CA 2 , a third controller TC 3  that has control over the third area CA 3 , and a fourth controller TC 4  that has control over the fourth area CA 4 . 
     As shown in  FIG. 2 , each of the first controller TC 1  to the fourth controller TC 4  of the controller TC includes a state information request transmitter  40 . The state information request transmitter  40  periodically transmits a state information request to the in-vehicle controller VC of each traveling vehicle V located in the area CA (first area CA 1  to fourth area CA 4 ) under the control. The in-vehicle controller VC of each traveling vehicle V transmits state information of the traveling vehicle V of its own to the controller TC in response to the state information request transmitted periodically from the controller TC. Communications related to state information requests and state information exchanged between the in-vehicle controller VC and the controller TC, are performed regularly at predetermined time intervals. The controller TC receives state information from the traveling vehicles V periodically to thereby grasp the latest state of the traveling vehicles V located in the area CA under the control thereof as well as the latest state of various instructions transmitted to the traveling vehicles V from the controller TC itself, and controls the traveling vehicles V. 
     Each of the first controller TC 1  to the fourth controller TC 4  controls (manages) the number of traveling vehicles V entering each of the first area CA 1  to the fourth area CA 4  under its control. As shown in  FIG. 2 , the first controller TC 1  to the fourth controller TC 4  each include an entry permission request receiver  41 , a vehicle counter  42 , a position confirmer  43 , a determiner  44 , an entry permitter  45 , and a permission transmitter  46 . In the controller TC, each of the first controller TC 1  to the fourth controller TC 4  stores information required (for example, maximum number N 1  of vehicles V allowed to enter area CA, and threshold value Ns described later) to control the number of traveling vehicles V to enter the area CA under its own control (first area CA 1  to fourth area CA 4 ), a control program, and so forth in a memory storage device not shown in the drawings. The configuration of the controller TC is not limited to the configuration shown in  FIG. 2  and may have another configuration. 
     In the following description, the first controller TC 1  having control over the first area CA 1  will be described as an example. However, the configuration and control contents of each of the second controller TC 2  to the fourth controller TC 4  that control the other areas, the second area CA 2  to the fourth area CA 4 , are similar to those of the first controller TC 1 . 
     The entry permission request receiver  41  receives entry permission requests from traveling vehicles V outside the first area CA 1  under the control of the first controller TC 1 . If the route from the traveling start position PS to the traveling end position PE includes the first area CA 1  under the control of the first controller TC 1 , the in-vehicle controller VC of each traveling vehicle V transmits an entry permission request to the first controller TC 1  prior to entering the first area CA 1 . For example, while traveling toward an entry point Ep for the first area CA 1 , an entry permission request for the first area CA 1  is transmitted when the distance to the entry point Ep becomes equal to or less than a predetermined distance. Alternatively, a point corresponding to the entry point Ep, at which a traveling vehicle V entering the first area CA 1  from the entry point Ep is supposed to transmit an entry permission request, may be preliminarily defined, and the traveling vehicle V may transmit an entry permission request for the first area CA 1  at the time of passing through the point. 
     The entry permission request receiver  41  includes an entry permission request into state information that is a response to a state information request transmitted from the state information request transmitter  40  and transmits it. That is to say, an entry permission request is transmitted to the controller TC through cyclic communication (polling communication) performed between the controller TC and the in-vehicle controller VC. Alternatively, transmission of an entry permission request may be performed separately from that of state information, from the in-vehicle controller VC of the traveling vehicle V to the first controller TC 1 . If an entry permission request is received from the in-vehicle controller VC of a traveling vehicle V, the entry permission request receiver  41 , at the same time, also acquires time information indicating the time at which the state information request was sent (or received). 
     When the entry permission request receiver  41  receives an entry permission request from the in-vehicle controller VC of a traveling vehicle V outside the first area CA 1  under control, the vehicle counter  42  counts the number Nv of traveling vehicles V present in the first area CA 1  under control at the time of receipt. In order for the vehicle counter  42  to count the number Nv of the traveling vehicles V present in the first area CA 1  under control, a reference is made to information indicating the current position (current position information) of each traveling vehicle V that is included in the state information received from a plurality of traveling vehicles V as a response to the state information request just recently transmitted from the controller TC. The vehicle counter  42  counts the number Nv of traveling vehicles V, the current position information of which are within the first area CA 1  under control. 
     When the entry permission request receiver  41  receives an entry permission request from the in-vehicle controller VC of a traveling vehicle V located outside the first area CA 1  under control, the vehicle counter  42  calculates the remaining number Nr of traveling vehicles V allowed to enter the first area CA 1  from outside the first area CA 1 . The vehicle counter  42  makes a reference to the maximum number N 1  of traveling vehicles V allowed to travel in the first area CA 1 , which is stored preliminarily in the controller TC. The vehicle counter  42  subtracts the number Nv of the traveling vehicles V present in the first area CA 1  at this time from the maximum number N 1  of vehicles, which has just been referenced, to thereby acquire the remaining number Nr of traveling vehicles V that are allowed to enter the first area CA 1  (Nr=N 1 −Nv). 
     The position confirmer  43  confirms the position of the traveling vehicle V that is the transmission origin (request origin) of the entry permission request received by the entry permission request receiver  41 . The position confirmer  43  confirms the current position information of the traveling vehicle V that is included in the state information of the traveling vehicle V received as a response to the state information request transmitted from the controller TC. The position confirmer  43  confirms whether or not the position of the traveling vehicle V from which the entry permission request has been received, is within a predetermined entry region EA set in the first area CA 1 . For example, by providing an indicator marking mentioned above at the entrance of the entry region EA, the position confirmer  43  can recognize whether or not a traveling vehicle V has entered the predetermined entry region EA. Also, by preliminarily setting, in the entry region EA, the entry point P 1  (stop position) at which a traveling vehicle V is to stop and providing an indicator marking at the stop position, the position confirmer  43  can recognize a traveling vehicle V being in a stop state at an entry point P 1 . 
     As described above, in the present preferred embodiment, an aspect has been described in which whether or not a traveling vehicle V has entered the entry region EA is determined on the controller TC side based on the current position information of the traveling vehicle V, however, the determination may be made on the traveling vehicle V side and the determination result may be transmitted to the controller TC. For example, at the moment a traveling vehicle V reads the indicator marking mentioned above, the in-vehicle controller VC of the traveling vehicle V may transmit to the controller TC information indicating its entry to the entry region EA having been made. Transmission of this information may be performed through cyclic communication (polling communication) performed between the controller TC and the in-vehicle controller VC, or through interrupting communication performed in a manner of interrupting this cyclic communication. 
     As shown in  FIG. 1 , the entry region EA is set at a predetermined position outside the first area CA 1 . The entry region EA is set, for example, on the near side of a traveling vehicle V in the traveling direction thereof with respect to the entry point Ep, at which entry to the circular track  11  of the first area CA 1  is made. The entry point Ep is a connection portion (merging portion) between the circular track  11  and each connection track  12  that defines and functions as an entry route for a traveling vehicle V to enter the circular track  11  of the first area CA 1  under the control from other areas, such as the second area CA 2  to the fourth area CA 4 . 
     The entry region EA is set on the connection track  12  or the circular track  11  of the other areas, such as the second area CA 2  to the fourth area CA 4 , on the near side of the entry point Ep. In the present preferred embodiment, the entry region EA is set on the circular track  11  of each of the other areas, such as the second area CA 2  to the fourth area CA 4 , just short of a branching point Sp that branches off to the connection track  12  connected to the first area CA 1 . In the present preferred embodiment, a plurality of entry regions EA for the first area CA 1  under the control of the first controller TC 1  are set outside the first area CA 1 . Each entry region EA is set to have a length in the traveling direction of traveling vehicles V that prevents, when one traveling vehicle V is located in an entry region EA, another traveling vehicle V from entering the entry region EA. For example, each entry region EA is set to have a length in which an ample distance for preventing a collision with a following traveling vehicle V is added to the dimension of a traveling vehicle V in the traveling direction thereof, and the following traveling vehicle V cannot enter the region. 
     As shown in  FIG. 2 , upon receiving an entry permission request from a traveling vehicle V, the determiner  44  determines whether or not the sum of the number of traveling vehicles V present in the first area CA 1  and the number of traveling vehicles V already permitted to enter the first area CA 1  reaches the maximum number N 1  of vehicles (or whether it is less than the maximum number N 1  of vehicles). It should be noted that the traveling vehicles V present in the first area CA 1  refers to traveling vehicles V that have obtained entry permission and have actually entered the first area CA 1 . Also, the traveling vehicles V already permitted to enter the first area CA 1  refers to traveling vehicles V that have obtained entry permission but have not entered the first area CA 1  yet. The traveling vehicles V already permitted to enter the first area CA 1  are traveling vehicles V that have already been determined (scheduled) to be present in the first area CA 1  in the near future. 
     If an entry permission request has been received from a traveling vehicle V, the determiner  44  determines whether or not the remaining number Nr of vehicles to the maximum number N 1  of vehicles allowed to enter the first area CA 1  is equal to or less than a preliminarily set threshold value (predetermined number) Ns. Here, the threshold value Ns is less than the maximum number N 1  of vehicles. In the present preferred embodiment, for example, the maximum number N 1  of vehicles allowed to enter the first area CA 1  under the control of the first controller TC 1  is 8 (vehicles), and the threshold value Ns is 2 (vehicles). 
     The determiner  44  can change the threshold value Ns. For example, in the case where at least one of the other areas, such as the second area CA 2  to the fourth area CA 4 , is closed due to maintenance work or the like and the number of connection tracks  12  defining and functioning as entry routes for the first area CA 1  under the control has changed, the threshold value Ns is changed according to the number of usable entry regions EA or according to the operating status (such as article transfer operation) of the traveling vehicles V in the first area CA 1 . The determiner  44  can increase the above threshold value Ns as the number of entry routes to the circular track  11  of the first area CA 1  under the control of the first controller TC 1  increases. 
     If the determiner  44  determines the remaining number Nr of vehicles to the maximum number N 1  of vehicles as being equal to or less than the threshold value Ns, the entry permitter  45  temporarily holds entry permission requests from traveling vehicles V. In the example of the present preferred embodiment, in the case where the remaining number Nr of vehicles to the maximum number N 1 =8 of vehicles allowed to enter the first area CA 1  under the control of the first controller TC 1  is equal to or less than the threshold value Ns=2, entry permission requests from traveling vehicles V are held temporarily or for a certain period of time. 
     In the case where entry permission requests from traveling vehicles V are held for a certain period of time, the entry permitter  45  grants entry permission to one traveling vehicle V that arrives first (arrives earliest) at the entry region EA for the first area CA 1  among the traveling vehicles V from which entry permission requests have been received. For example, in the case where entry permission requests have been received from a plurality of traveling vehicles V traveling in the same second area CA 2 , entry permission is granted to one traveling vehicle V that arrives first at (reaches first) the entry region EA to the first area CA 1  among the plurality of traveling vehicles V from which entry permission requests have been received. 
     Also, the entry permitter  45  grants entry permission to one traveling vehicle V that arrives first at any one of the plurality of entry regions EA for the first area CA 1 . In the case where entry permission requests from traveling vehicles V are held for a certain period of time, the entry permitter  45  grants entry permission into the first area CA 1  to one traveling vehicle V that reaches first any of the entry regions EA respectively set in the second area CA 2  to the fourth area CA 4  under the control. 
     In the case where entry permission requests from traveling vehicles V are held for a certain period of time, the entry permitter  45  may grant entry permission to a traveling vehicle V that stops first at the entry point P 1  in the entry region EA, among the traveling vehicles V from which entry permission requests have been received. For example, in the case where a plurality of traveling vehicles V from which entry permission requests have been received all arrive in entry regions EA at almost the same time, entry permission may be granted to the traveling vehicle V that stops first at the entry point P 1  (stop position) provided at a predetermined position in each entry region EA. The entry point P 1  is a position just short of the route for entering the first area CA 1 . The entry permitter  45  acquires time information at which the traveling vehicle V stopped. 
     If the determiner  44  determines the remaining number Nr of vehicles as being greater than the threshold value Ns, the entry permitter  45  may grant traveling vehicles V permission to enter the first area CA 1  in the order of receipt of the entry permission requests. In the example of the present preferred embodiment, if the remaining number Nr of vehicles to the maximum number N 1 =8 of vehicles allowed to enter the first area CA 1  is greater than the threshold value Ns=2, permission to enter the first area CA 1  is granted to traveling vehicles V in the order of receipt of the entry permission requests. 
     The permission transmitter  46  transmits information regarding entry permission to the traveling vehicles V to which entry permission has been granted by the entry permitter  45 . The permission transmitter  46  transmits nothing to the traveling vehicles V to which entry permission has not been granted by the entry permitter  45 . That is to say, the first controller TC 1  ignores entry permission requests from such traveling vehicles V. It should be noted that the permission transmitter  46  may transmit information regarding entry refusal to the traveling vehicles V to which entry permission has not been granted by the entry permitter  45 . Also, instead of transmitting information regarding entry permission from the permission transmitter  46 , entry permission that specifies a traveling vehicle V may be transmitted in addition to the state information request transmitted from the state information request transmitter  40 . 
     If information regarding entry permission is received from the permission transmitter  46 , the in-vehicle controller VC of each traveling vehicle V that has transmitted an entry permission request causes the traveling vehicle V to move forward from the entry region EA of the second area CA 2  to the fourth area CA 4  and move into the first area CA 1  via the connection track  12 . If information regarding entry permission is not received from the permission transmitter  46 , the in-vehicle controller VC of each traveling vehicle V that has transmitted an entry permission request does not cause the traveling vehicle V to move into the first area CA 1  and causes the traveling vehicle V to travel to the entry region EA and then stop. The in-vehicle controller VC may cause the traveling vehicle V to travel in circle on the circular track  11  within the second area CA 2  to the fourth area CA 4 , instead of causing it to stop at the entry region EA. 
       FIG. 3  is a flowchart showing an example of a traveling vehicle control method according to a preferred embodiment of the present invention.  FIG. 3  illustrates an example of the operation flow of the controller TC. In the following, operations performed when the first controller TC 1  of the controller TC controls the number of traveling vehicles V in the first area CA 1  under the control will be described with reference to the flowchart shown in  FIG. 3 . The flow of the series of operations described below is repeatedly executed, for example, every time the state information request transmitter  40  transmits a state information request to the in-vehicle controller VC of each traveling vehicle V. The state information request transmitter  40  transmits state information requests sequentially to the in-vehicle controller VC of the respective traveling vehicles V at predetermined time intervals, that is, through cyclic communication (polling communication). 
     The first controller TC 1  issues entry permission in the order of receipt of entry permission requests from the traveling vehicles V. As described above, since the first controller TC 1  transmits state information requests sequentially to the respective traveling vehicles V, the order in which the traveling vehicles V (in-vehicle controllers VC) having received a state information request make entry permission requests may be reversed from the order in which traveling vehicles V traveling outside the first area CA 1  are queuing. That is to say, in some cases, a traveling vehicle V that made an entry permission request later may arrive at the entry region EA earlier than a traveling vehicle V that made an entry permission request first. In the case where these two traveling vehicles V are traveling in the same area (for example, the second area CA 2 ), if the traveling vehicle V that made the entry permission request later does not obtain entry permission, it will stop in the entry region EA. In the case where another traveling vehicle V in a stop state is present in the entry region EA, even if a traveling vehicle V that made an entry permission request first obtains entry permission, this traveling vehicle V will be stopped just short of the entry region EA and will not be allowed to enter the first area CA 1 . In the present preferred embodiment, as will be described below, such a situation is avoided and smooth entry of traveling vehicles V into the first area CA 1  is performed. 
     The state information request transmitter  40  transmits a state information request to the in-vehicle controller VC of each traveling vehicle V located in the areas CA (first area CA 1  to fourth area CA 4 ) under the control (Step S 01 ). The in-vehicle controller VC of each traveling vehicle V transmits state information to the controller TC in response to the state information request transmitted from the controller TC. If the route from the traveling start position PS to the traveling end position PE includes the first area CA 1  under the control of the first controller TC 1 , the in-vehicle controller VC of each traveling vehicle V transmits, prior to entering the first area CA 1 , an entry permission request to the first controller TC 1  along with state information or separately from state information. 
     The first controller TC 1  receives the state information transmitted from the in-vehicle controller VC of each traveling vehicle V. If there is an entry permission request from a traveling vehicle V outside the first area CA 1 , the entry permission request receiver  41  receives the entry permission request along with the state information received from each traveling vehicle V (Step S 02 ). If an entry permission request is received from the in-vehicle controller VC of a traveling vehicle V, the entry permission request receiver  41 , at the same time, also acquires time information indicating the time at which the entry permission request was sent. 
     After having transmitted the state information request in Step S 01 , when a preliminarily defined certain period of time has elapsed, the first controller TC 1  confirms whether or not an entry permission request has been received from any of the traveling vehicles V during its waiting time (Step S 03 ). In Step S 03 , the waiting time may be, for example, a duration of time until the next state information request is transmitted. If the entry permission request receiver  41  has not received an entry permission request (No in Step S 03 ), the first controller TC 1  ends the process. If the entry permission request receiver  41  has received an entry permission request (Yes in Step S 03 ), the vehicle counter  42  of the first controller TC 1  counts the number Nv of traveling vehicles being the sum of the number of traveling vehicles V present in the first area CA 1  under the control and the number of traveling vehicles V that have already been permitted to enter the first area CA 1  (Step S 04 ). 
     Next, the determiner  44  of the first controller TC 1  determines whether or not the number Nv of traveling vehicles V exceeds the maximum number N 1  of vehicles allowed to enter the first area CA 1  (Step S 05 ). If the number Nv of traveling vehicles V has reached the maximum number N 1  of vehicles (Yes in Step S 05 ), the first controller TC 1  ends the process without granting entry permission to any traveling vehicle V. If the number Nv of traveling vehicles V has not reached the maximum number N 1  of vehicles (No in Step S 05 ), the process proceeds to Step S 06 . 
     The vehicle counter  42  of the first controller TC 1  counts the remaining number Nr of vehicles V allowed to enter the first area CA 1  from outside the first area CA 1  under the control (Step S 06 ). In Step S 06 , the vehicle counter  42  makes a reference to the maximum number N 1  of the first area CA 1  preliminarily stored in the controller TC. The vehicle counter  42  subtracts the number Nv of the traveling vehicles V present in the first area CA 1  at this time from the maximum number N 1  of vehicles, which has just been referenced, to thereby calculate the remaining number Nr of traveling vehicles V that are allowed to enter the first area CA 1 . 
     Next, the position confirmer  43  of the first controller TC 1  confirms the position of the traveling vehicle V from which an entry permission request has been received by the entry permission request receiver  41 . The position confirmer  43  confirms whether or not the position of the traveling vehicle V from which an entry permission request has been received, is within the entry region EA for the first area CA 1  (Step S 07 ). If the position of the traveling vehicle V is not within the entry region EA (No in Step S 07 ), the first controller TC 1  ends the process. If the position of the traveling vehicle V is within the entry region EA (Yes in Step S 07 ), the process proceeds to Step S 08 . It should be noted that whether or not to perform Step S 07  is arbitrary, and Step S 07  need not be performed. For example, Step S 08 , which will be described later, may be executed after the remaining number Nr of vehicles allowed to enter the first area CA 1  has been counted in Step S 06 . 
     If an entry permission request has been received from a traveling vehicle V, the determiner  44  of the first controller TC 1  determines whether or not the remaining number Nr of vehicles to the maximum number N 1  of vehicles allowed to enter the first area CA 1  is equal to or less than the preliminarily set threshold value (predetermined number) Ns (Step S 08 ). If the determiner  44  determines the remaining number Nr of vehicles as being greater than the threshold value Ns (No in Step S 08 ), the entry permitter  45  grants traveling vehicles V permission to enter the first area CA 1  in the order of receipt of the entry permission requests (Step S 09 ). 
     If the determiner  44  determines the remaining number Nr of vehicles to the maximum number N 1  of vehicles as being equal to or less than the threshold value Ns (Yes in Step S 08 ), the first controller TC 1  temporarily holds entry permission requests from traveling vehicles V until a preliminarily defined certain period of time has elapsed (Step S 10 ). The certain period of time can be set to an arbitrary length of time. When the certain period of time has elapsed, the entry permitter  45  of the first controller TC 1  grants entry permission to only one traveling vehicle V that arrives first at the entry region EA for the first area CA 1  under the control (Step S 11 ). 
       FIG. 4  is a flowchart showing an example of the detailed process flow of Step S 11  in  FIG. 3 . As shown in  FIG. 4 , the entry permitter  45  determines whether or not entry permission requests have been received from two or more traveling vehicles V while entry permission requests from traveling vehicles V are being held (Step S 21 ). If an entry permission request has been received from only one traveling vehicle V located within the entry region EA (No in Step S 21 ), the entry permitter  45  grants entry permission to the traveling vehicle V (Step S 22 ). 
     If it is determined that entry permission requests have been received from two or more traveling vehicles V while entry permission requests from traveling vehicles V are being held (Yes in Step S 21 ), the entry permitter  45  grants entry permission to one traveling vehicle V that arrives first at the entry region EA set in the second area CA 2  to the fourth area CA 4  (Step S 23 ). In Step S 23 , regardless of whether two or more traveling vehicles V are located in the same area CA or are located in different areas CA, the entry permitter  45  grants entry permission to one traveling vehicle V that arrives first at any of the plurality of entry regions EA. In Step S 23 , if a plurality of traveling vehicles V that have made entry permission requests arrive almost at the same time at the entry region EA, the entry permitter  45  may grant entry permission to the traveling vehicle V that stops first at the entry point P 1  in the entry region EA, among the traveling vehicles V from which entry permission requests have been received. 
     Having granted the traveling vehicle V permission to enter the first area CA 1  in Step S 22  or Step S 23 , the entry permitter  45  adds 1 to the number of traveling vehicles V in the first area CA 1  (the number of vehicles Nv being the sum of the number of traveling vehicles V present in the first area CA 1  and the number of traveling vehicles V already permitted to enter the first area CA 1 ), and subtracts 1 from the remaining number Nr of vehicles (Step S 24 ). Next, the permission transmitter  46  of the first controller TC 1  transmits information regarding entry permission to the traveling vehicles V to which entry permission has been granted by the entry permitter  45  (Step S 25 ). The permission transmitter  46  does not transmit a response to the traveling vehicles V to which entry permission has not been granted by the entry permitter  45 . 
     If information regarding entry permission is received from the permission transmitter  46 , the in-vehicle controller VC of each traveling vehicle V that has transmitted an entry permission request causes the traveling vehicle V to enter the first area CA 1  from the entry region EA via the connection track  12 . If information regarding entry permission is not received from the permission transmitter  46 , the in-vehicle controller VC of each traveling vehicle V that has transmitted an entry permission request causes the traveling vehicle V to travel to the entry region EA and stop or continue to travel within the second area CA 2  to the fourth area CA 4 . 
       FIG. 5  is a diagram showing an example of the operations of the traveling vehicles V in the traveling vehicle system SYS.  FIG. 5  shows one specific example in the case where the first controller TC 1  controls the traveling vehicles V as described above. As shown in  FIG. 5 , if an entry permission request is transmitted from a traveling vehicle V 1  outside the first area CA 1  in a situation where the number of traveling vehicles V present in the first area CA 1  has reached the maximum number N 1  (for example, 8) of vehicles, the process determines Yes in Step S 05  of  FIG. 3 . As a result, the traveling vehicle V 1  that has transmitted an entry permission request will not be granted entry permission by the first controller TC 1  even if it arrives first at the entry region EA. Therefore, the traveling vehicle V 1  cannot enter the first area CA 1  until the number of traveling vehicles V present in the first area CA 1  becomes less than the maximum number N 1  of vehicles. 
       FIG. 6  is a diagram showing another example of the operations of the traveling vehicles V in the traveling vehicle system SYS.  FIG. 6  shows a case where one traveling vehicle V 2  located at the entry region EA outside the first area CA 1  transmits an entry permission request in a situation where the number of traveling vehicles V within the first area CA 1  under the control of the first controller TC 1  is less than the maximum number N 1  (for example, 8) of vehicles, and the remaining number Nr of vehicles to the maximum number N 1  of vehicles is greater than the threshold value Ns (for example, 2) (the remaining number Nr of vehicles is 4 in the example shown in  FIG. 6 ). 
     In such a case, the process determines No in Step S 08  of  FIG. 3  for the traveling vehicle V 2 . As a result, in Step S 09 , the first controller TC 1  grants the traveling vehicle V 2  entry permission. Having obtained entry permission from the first controller TC 1 , the traveling vehicle V 2  moves forward from the entry region EA and enters the circular track  11  of the first area CA 1  under the control of the first controller TC 1  via the connection track  12 . Thus, when the remaining number Nr of vehicles to the maximum number N 1  of vehicles is ample, it is possible for traveling vehicles V to perform smooth entry into the first area CA 1  by granting entry permission to the traveling vehicles V in the order of receipt of entry permission requests without temporarily holding entry permission requests from the traveling vehicles V. 
       FIG. 7  to  FIG. 11  show examples of cases where a traveling vehicle V transmits an entry permission request in a situation where the number of traveling vehicles V within the first area CA 1  under the control of the first controller TC 1  is less than the maximum number N 1  (for example, 8) of vehicles, and the remaining number Nr of vehicles to the maximum number N 1  of vehicles is equal to or less than the threshold value Ns (for example, 2) (for example, the number of vehicles within the first area CA 1  is 6). 
       FIG. 7  is a diagram showing another example of the operations of the traveling vehicles V in the traveling vehicle system SYS.  FIG. 7  shows a case where a traveling vehicle V 3  transmits an entry permission request in a state where the traveling vehicle V 3  is located just short of the entry region EA outside the first area CA 1  (the entry region EA of the second area CA 2 ). In this case, the process of Step S 07  determines No since the traveling vehicle V 3  has not reached the entry region EA, and the traveling vehicle V 3  may not be granted entry permission from the first controller TC 1 , or the processes of Step S 08  and thereafter may be performed without performing Step S 07 . In such a case, if the traveling vehicle V 3  arrives first at the entry region EA, the traveling vehicle V 3  will be granted entry permission in Step S 11 . 
       FIG. 8  is a diagram showing still another example of the operations of the traveling vehicles V in the traveling vehicle system SYS.  FIG. 8  shows a case where entry permission requests are transmitted respectively from a plurality of (for example, 2) traveling vehicles V 5 , V 6  located in the same area CA (for example, the second area CA 2 ). In this case, of the two traveling vehicles V 5 , V 6 , the traveling vehicle V 5  located ahead in the traveling direction arrives first at the entry region EA. As a result, in Step S 11  (or Step S 23 ), the first controller TC 1  grants entry permission to the traveling vehicle V 5  located ahead in the traveling direction. Meanwhile, the traveling vehicle V 6  located behind in the traveling direction is unable to enter the entry region EA because the traveling vehicle V 5  ahead thereof in the traveling direction is located in the entry region EA. Therefore, the traveling vehicle V 6  would not arrive first at the entry region EA even if it transmitted an entry permission request before the traveling vehicle V 5  did, and as a result, the first controller TC 1  does not grant entry permission to the traveling vehicle V 6 . 
     As described above, the entry region EA preferably has a length to accommodate one traveling vehicle V in the traveling direction of traveling vehicles V, and therefore, only one traveling vehicle V can enter the entry region EA and multiple traveling vehicles V will not enter the entry region EA. As a result, it is possible to easily confirm one traveling vehicle V that arrives first at the entry region EA. 
       FIG. 9  is a diagram showing still another example of the operations of the traveling vehicles V in the traveling vehicle system SYS.  FIG. 9  shows a case where entry permission requests are transmitted respectively from traveling vehicles V 7 , V 8  that are located respectively in a plurality of areas CA (the second area CA 2  and the third area CA 3 ). In this case, of the two traveling vehicles V 7 , V 8 , the traveling vehicle V 7  arrives first at the entry region EA. As a result, in Step S 11  (or Step S 23 ), the first controller TC 1  grants entry permission to the traveling vehicle V 7 . Meanwhile, the traveling vehicle V 8  has not arrived at the entry region EA and therefore, the first controller TC 1  does not grant entry permission to the traveling vehicle V 8  even if it had transmitted an entry permission request before the traveling vehicle V 7  did. 
     It should be noted that a determination is made again according to the control flow of the first controller TC 1  described above (the flowchart of  FIG. 3 ) and the traveling vehicle V 8  will be the traveling vehicle V to arrive first at the entry region EA after the traveling vehicle V 7  has entered the first area CA 1 , and as a result, the first controller TC 1  may grant entry permission to the traveling vehicle V 8 . 
       FIG. 10  is a diagram showing still another example of the operations of the traveling vehicles V in the traveling vehicle system SYS.  FIG. 10  shows a case where after entry permission requests have been transmitted from two traveling vehicles V 7 , V 9 , the traveling vehicle V 9  enters the entry region EA first and the traveling vehicle V 7  enters the entry region EA later, but the traveling vehicle V 7  stops first at the entry point P 1 . In such a case, the first controller TC 1  may grant entry permission to the traveling vehicle V 7  that stopped at the entry point P 1  first. That is to say, the first controller TC 1  may determine the traveling vehicle V 7  that stopped at the entry point P 1  first as having arrived first at (as having reached first) the entry region EA and may grant entry permission to the traveling vehicle V 7 . 
     For example, even if the traveling vehicle V 9  enters the entry region EA first, traveling of the traveling vehicle V 9  may be stopped or decelerated after the entry in some cases, and as a result, the traveling vehicle V 7  may stop at the entry point P 1  first (may arrive at a position from which earliest entry into the first area CA 1  can be made). In such a case, allowing the traveling vehicle V 7  to enter the first area CA 1  first would result in the better operation efficiency of the traveling vehicles, and therefore, the first controller TC 1  may determine the traveling vehicle V 7  as having arrived first at the entry region EA and may grant entry permission to the traveling vehicle V 7 . 
     In the example shown in  FIG. 10 , in the case where the number of traveling vehicles V that have transmitted entry permission requests is 2 (traveling vehicle V 7  and traveling vehicle V 9 ), and the remaining number Nr of vehicles to the maximum number N 1  (for example, 8) of vehicles is equal to or less than the threshold value Ns (for example, 2), the first controller TC 1  may grant entry permission to the two traveling vehicles V 7  and V 9  both. 
       FIG. 11  is a diagram showing still another example of the operations of the traveling vehicles V in the traveling vehicle system SYS.  FIG. 11  shows a case where entry permission requests are transmitted from traveling vehicles V 7 , V 9 , and V 10  that are located respectively in three areas, the second area CA 2 , the third area CA 3 , and the fourth area CA 4 . In this case, the number of traveling vehicles V that have transmitted entry permission requests is 3 (traveling vehicles V 7 , V 9 , and V 10 ), and exceeds the remaining number Nr (for example, 2) of vehicles to the maximum number N 1  (for example, 8) of vehicles. In such a case, of the three traveling vehicles V 7 , V 9 , and V 10 , the traveling vehicles V 7 , V 9  that arrived first at the entry region EA (or stopped first at the entry point P 1 ) are granted entry permission in sequence or at the same time. 
     Meanwhile, as for the remaining one traveling vehicle V 10 , the number of traveling vehicles V in the first area CA 1  exceeds the maximum number N 1  of vehicles at the moment at which entry permission is granted to the traveling vehicles V 7 , V 9 , and therefore, the process determines Yes in Step S 05  and the first controller TC 1  does not grant entry permission to the traveling vehicle V 10 . As a result, the traveling vehicle V 10  stops at the entry region EA or continues to travel on the circular track  11  of the fourth area CA 4 . 
     As described above, according to the present preferred embodiment, when entry permission requests for an area CA are received from traveling vehicles V, if the remaining number Nr of vehicles to the maximum number N 1  of vehicles allowed to enter the area CA is equal to or less than the threshold value Ns, the entry permission requests from the traveling vehicles V are temporarily held and entry permission is granted to one traveling vehicle V that arrives first at the entry region EA for the area CA. As a result, entry permission will not be granted for an entry permission request from a traveling vehicle V that has not arrived at the entry region EA despite the presence of a traveling vehicle V that arrived at the entry region EA first. It is therefore possible to avoid a plurality of traveling vehicles V from becoming unable to enter an area CA and becoming stuck, and it is possible to enable smooth entry of traveling vehicles V into the area CA. 
     If the determiner  44  determines the remaining number Nr of vehicles as being greater than the threshold value Ns, the entry permitter  45  grants traveling vehicles V permission to enter the area CA in the order of receipt of entry permission requests. As a result, when the remaining number Nr of vehicles to the maximum number N 1  of vehicles allowed to enter the area CA is ample, it is possible to perform smooth entry of traveling vehicles V into the area CA by granting entry permission to the traveling vehicles V in the order of receipt of entry permission requests without temporarily holding entry permission requests from the traveling vehicles V. 
     Even in a case where a plurality of entry regions EA are provided in one of the areas CA, the entry permitter  45  grants entry permission to one traveling vehicle V that arrives first at any one of the plurality of entry regions EA. As a result, even when a plurality of entry regions EA are provided, it is possible to perform smooth entry of the traveling vehicles V into the area CA and prevent a plurality of traveling vehicles V from becoming unable to enter the area CA and becoming stuck in each of the entry regions EA. 
     Preferred embodiments of the present invention have been described above. However, the technical scope of the present invention is not limited to the description of the above preferred embodiments. It is also apparent to those skilled in the art that various modifications or improvements can be added to the above preferred embodiments. The technical scope of the present invention also encompasses one or more of modifications or improvements. The order of executing processes shown in the preferred embodiments can be realized in an arbitrary order unless an output of the previous processing is used in the following processing. While operations in the above preferred embodiments have been described with expressions such as “first”, “next”, and “subsequently” for the sake of convenience, the operations need not always be implemented in that order. 
     Furthermore, in the above preferred embodiments, the configurations have been described as examples in which a host controller MC and a controller TC are provided in the traveling vehicle system SYS, however, the present invention is not limited to this configuration. For example, a single controller may include the functions of both the host controller MC and the controller TC. In the above preferred embodiments, the configurations have been described as examples in which the controller TC is provided as a separate unit from the in-vehicle controller VC of the traveling vehicle V, however, the present invention is not limited to this configuration. For example, the function of the controller TC may be realized as a part of the function of the in-vehicle controller VC. 
     While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.