JP3187351B2 - Automatic guided vehicle system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic guided vehicle system that travels on the ground or a ceiling, and more particularly to an automatic guided vehicle system that connects between a truck yard and an automatic warehouse.

[0002]

2. Description of the Related Art An automatic guided vehicle system is used for transporting articles in factories and warehouses. In the automated guided vehicle system, several to several tens of automated guided vehicles are used and run along the track, or run while recognizing the current position on the track by scanning a position recognition pattern with a laser or the like. Let it. The unmanned guided vehicle becomes vacant (idle) upon completion of the executing transfer command, and the vacant unmanned guided vehicle stops at that position, for example, and waits for the next transfer command.

[0003] The inventor of the present invention has studied on increasing the efficiency of the system by controlling the standby position of an empty automatic guided vehicle, and arrived at the present invention.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to make an automatic guided vehicle stand by at a truck yard side and an automatic warehouse side according to the frequency of a transfer start position, and to efficiently deploy the automatic guided vehicle. .

[0005]

According to the present invention, articles are transported by a plurality of automatic guided vehicles at least between a zone on the truck yard side and a zone on the automatic warehouse side, and empty automatic guided vehicles are provided in each zone. In the system in which the vehicle is made to stand by at the standby position, the frequency at each time when the zone on the truck yard side is the transfer start position, obtained from the statistics of the past transfer start position, and the zone on the automatic warehouse side is the transfer start position There is provided a deployment means having a timer for raising and lowering the priority of the standby position of the zone on the truck yard side and the priority of the standby position of the zone on the automatic warehouse side according to the frequency according to time. And an automatic guided vehicle system.

In this specification, the term "idle" means a state in which a transfer command is not assigned to an automatic guided vehicle, has no operation other than charging or other transfer, and waits for a transfer command. The deployment means that the idle automatic guided vehicle stands by at a standby position (WP). It should be noted that the automatic guided vehicle does not need to be stopped literally during the deployment, and may be moved to a higher priority standby position, for example, if it becomes available. The term "priority is temporally variable" means that the priority is changed at a time interval corresponding to a change in the distribution state of the transport command. Furthermore, it is preferable to assign different priorities to the individual standby positions in the zone in order to limit the concentration of the automatic guided vehicle in each zone described below. good.

[0007]

According to the present invention, at least the zone on the truck yard side and the zone on the automatic warehouse side are
Based on past statistics, the frequency at each time as the transfer start position is calculated, and the priority between the standby position of the zone on the truck yard side and the standby position of the zone on the automatic warehouse side is increased or decreased according to the calculated frequency at each time. Let it. Up and down of the priority is performed by a deployment unit having a timer. For this reason, in the automatic guided vehicle system connecting the truck yard and the automatic warehouse, the transport efficiency is improved.

[0008]

1 to 7 show an embodiment. FIG. 1 shows a configuration of an automatic guided vehicle system according to an embodiment. A traveling route 10 is provided inside a factory, a warehouse, or the like.
0 may be tracked or untracked. Stations 11 to 29 are provided along the traveling route 10, and the traveling route 10 is divided into, for example, five zones Z1 to Z5. The division into zones has a meaning such as a zone connected to a truck yard or the like via a forklift or a conveyor, a zone connected to an automatic warehouse system, a zone connected to a processing device such as a machine tool, or the like. .

[0009] Unmanned guided vehicles 31 to 31 along the traveling route 10
34 travels, receives the transfer of articles from the station, and runs and transfers to another station. Here, a station for transferring articles to the automatic guided vehicle is referred to as a transfer start position. When the automatic guided vehicle executes the transfer command assigned from the system computer described later and ends, the unmanned guided vehicle stops at the waiting position (WP) indicated by ● in FIG. 1 and stands by. The standby position depends on the layout and system operation, but is preferably provided in front of the transfer station, in front of the branch route, or in a sub route that does not hinder the passage of the automatic guided vehicle traveling on the main route. However, for example, the idle automatic guided vehicle may be moved to the next designated or higher priority standby position if it becomes available, or may be moved to the next standby position every time a predetermined time elapses. You may move it.

As shown in FIG. 2, the automatic guided vehicles 31 to 34 are managed by the system computer 40, and an automatic guided vehicle management unit 42 communicates with the automatic guided vehicles 31 to 34 by wire or wireless communication. Each automatic guided vehicle reports the current position, the execution status of the transfer command, and the like. The unmanned guided vehicle management unit 42 assigns a transfer command to each of the unmanned guided vehicles 31 to 34, and specifies a standby position when the transfer command ends. 44
Is a timer that outputs, for example, the time of the day, the day of the week, and the day of each month, and the deployment management unit 56 described later changes the priority of each standby position accordingly. A station management unit 46 communicates with and manages the stations 11 to 29.

Reference numeral 48 denotes a bus in the system computer 40, which receives a transfer command from a host computer, reports the result, and allocates the transfer command received by the host I / O 50 to the automatic guided vehicle to execute the command. Part 52
Etc. are connected. A route table management unit 54 stores the required travel time between the stations along the travel route 10 in, for example, a graph format, and searches for an unmanned transport vehicle that can execute the transport command in the shortest time.

Reference numeral 56 denotes a deployment management unit which determines and manages a standby position of an idle automatic guided vehicle. The priority of the standby position is used as a criterion for determining the standby position, and the priority changes according to the signal of the timer 44. For example, in the morning when there are many garages from the truck, the priority of the zone on the track yard side is set. The concentration of idle automatic guided vehicles is increased to increase the priority of the zone on the automatic warehouse side, for example, in a time zone when there are many outgoings in the evening, and the idle automatic guided vehicles are concentrated. Then, during the daytime, the priorities of the respective zones are made substantially uniform, for example. Note that the priority can change at any day of the week or month, and can be optimized by changing the time over time according to the statistics of the past transfer start position.

Reference numeral 58 denotes a transfer command analyzing unit, for example, the past 10
A distribution of the transport start position for each zone in a time of about minutes to 3 hours is provided, and a distribution of the transport start position in a future time of about 10 minutes to 1 hour is predicted for each zone from the transition. If the predicted value exceeds the allowable range on which the priority is designated by the timer 44, for example, in the morning or evening, the priority determined by the timer 44 is changed.

The priorities may be given a common priority for each zone. However, in order to prevent excessive concentration of unmanned guided vehicles in a specific zone, different priorities are assigned to individual standby positions in the zone. Is given. In order to prevent the concentration of unmanned traveling vehicles in a specific zone, an upper limit may be provided for the number of unmanned traveling vehicles in the zone. For example, the number of unmanned traveling vehicles may be either running or idle. It is preferable to count the total number without counting.

The concentration of unmanned vehicles will be described. When unmanned traveling vehicles concentrate in one zone, when it is necessary to start conveyance in another zone, the waiting time until the start of conveyance increases. The zone where unmanned vehicles are concentrated is often a zone where the distribution of the transfer start position is high, but if only this zone is prioritized, a command starting in a zone where the distribution of the transfer start position is low requires a long time to execute . Further, when unmanned traveling vehicles concentrate in a specific zone, the traveling route is blocked and a situation close to deadlock occurs, and the transport efficiency is reduced. Therefore, for example, it is preferable to prevent the concentration of unmanned transport vehicles in one zone regardless of whether the vehicle is idle or running, and the method is to set an upper limit on the number of unmanned transport vehicles having a destination in a specific zone, Arbitrary such as limiting the number of standby positions in the zone.

The operation of the embodiment will be described with reference to FIGS. FIG. 3 shows the operation of the embodiment as a whole. A system mode for performing an assignment subroutine (FIG. 4) in response to the generation of a transfer command and changing the priority of the standby position in accordance with the month, day, time, or the like. A subroutine (FIG. 5) is performed, a transport command analysis subroutine (FIG. 6) for analyzing the distribution of the transport start position in the transport command is performed, and a deployment subroutine (FIG. 7) for determining the deployment of the idle automatic guided vehicle is performed.

In the assignment subroutine shown in FIG. 4, when a transfer command is issued, the command is assigned to an automatic guided vehicle that can process the command in the shortest time. Route table management unit 5
4, the required time for the traveling route from the current position of the automatic guided vehicle to the transport start position of the article is calculated from the total required traveling time between the points stored in the route table. Then, the transfer command is assigned to the automatic guided vehicle that can execute the transfer command in the shortest time. Each time the transfer command is executed and completed, the corresponding assignment is deleted and the process returns to the main loop from the assignment subroutine.

In the system mode subroutine of FIG.
A signal such as a month, a day, a time, or a day of the week is obtained from the timer 44, and the deployment management unit 56 responds accordingly to the signals of the zones Z1-Z5.
Specify the priority of each standby position. For example, the priority of the zone on the truck yard side is increased during the morning when there is a lot of entry from the truck, and the priority on the automatic warehouse side is increased during the evening when there are many exits to the truck yard. If the priority of each standby position in a zone is made common, an automatic guided vehicle tends to concentrate in a specific zone. Therefore, an upper limit is set for the number of automatic guided vehicles having the zone as a destination for each zone. . In this way, the priority of each standby position is determined.

In the transfer command analysis subroutine of FIG. 6, the transfer command start position in the transfer command is added for each zone, and for example, a moving average of the distribution for each zone in the past about one hour is obtained. Then, the distribution of the subsequent transfer start position is predicted from the tendency of the moving average or the value of the moving average itself. If this distribution exceeds the allowable range, the priority of each zone is changed.
In this way, a non-periodic change in the distribution of the transfer start position, which cannot be obtained only by the signal from the timer 44, is processed by the transfer command analysis subroutine. Note that the processing in the system mode in FIG. 5 and the processing in the transfer command analysis in FIG. 6 both aim to change the priority of the zone in real time in accordance with the distribution of the transfer start positions. Only one may be provided.

FIG. 7 shows a subroutine for deploying an idle automatic guided vehicle. This subroutine is processed each time the transfer instruction is completed and an idle automatic guided vehicle is generated. The subroutine is moved to a standby position which has a high priority and is not a destination of another automatic guided vehicle and waits. If there are a plurality of standby positions having the same priority value, a standby position that can move in the shortest time is assigned. The travel time to the standby position is determined by the route table management unit 5
4, the required time for the traveling route from the current position of the automatic guided vehicle to the standby position is obtained from the total required traveling time between the points stored in the route table.

In the embodiment, the idle automatic guided vehicle is made to stand by at a standby position having a high priority. The priority is determined according to the distribution of the transport start position, and is variable over time.
For this reason, an idle automatic guided vehicle is preferentially provided in a zone where the distribution frequency of the transfer start position is high, and the waiting time from the generation of the transfer command to the execution thereof can be shortened. The priority is temporally variable, and the priority changes each time the distribution frequency of the transfer start position changes, so that the automatic guided vehicle can always be efficiently deployed.

Further, the concentration of the automatic guided vehicle in a specific zone is restricted, so that a zone in which a transfer instruction is issued and executed for a long time is prevented. Further, by preventing the automatic guided vehicles from concentrating on a specific zone, it is possible to prevent the traveling route from being congested and falling into a deadlock state.

Although a specific example has been shown in the embodiment, the present invention is not limited to this. The concept of the present invention is effective and can be arbitrarily changed as long as it is effectively equivalent.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an automatic guided vehicle system according to an embodiment.

FIG. 2 is a block diagram showing a relationship between the automatic guided vehicle and the system computer in the embodiment.

FIG. 3 is a flowchart illustrating overall processing in the embodiment.

FIG. 4 is a flowchart illustrating an allocation process according to the embodiment.

FIG. 5 is a flowchart illustrating priority change to a standby position according to a system mode in the embodiment.

FIG. 6 is a flowchart illustrating a change in the priority of a standby position based on a transfer command analysis in the embodiment.

FIG. 7 is a flowchart illustrating an algorithm for designating a standby position in the embodiment.

[Explanation of symbols]

 Reference Signs List 10 traveling route 11 to 29 station 31 to 34 automatic guided vehicle 40 system computer 42 automatic guided vehicle management unit 44 timer 46 station management unit 48 bus 50 upper I / O 52 allocation unit 54 route table management unit 56 deployment management unit 58 transportation command Analysis section Z1 to Z5 zone

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G05D 1/00-1/12

Claims (1)

(57) [Claims] An article is conveyed by a plurality of automatic guided vehicles at least between a zone on a truck yard side and a zone on an automatic warehouse side, and stands by at a standby position where an empty automatic guided vehicle is provided in each zone. In this system, the frequency by time when the zone on the truck yard side is the transport start position and the frequency by time when the zone on the automatic warehouse side is the transport start position, obtained from the statistics of the past transport start position In response to the above, a deployment means having a timer is provided for raising and lowering the priority of the standby position of the zone on the truck yard side and the priority of the standby position of the zone on the automatic warehouse side, Automatic guided vehicle system.