JP3212029B2 - 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, on a ceiling, or the like, and in particular, to the removal of a standby automatic guided vehicle on a traveling route.

[0002]

2. Description of the Related Art An automatic guided vehicle system is used for transporting articles in factories and warehouses. An unmanned guided vehicle system uses several to several tens of unmanned guided vehicles and travels them along a track, or scans a pattern for position recognition or track recognition with a laser or a magnetic head, etc. Run while recognizing the current position with. 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] When an automatic guided vehicle stands by on a traveling route, the traveling route of a subsequent automatic guided vehicle may be blocked.
Further, since the subsequent automatic guided vehicle generally does not know the presence of the automatic guided vehicle ahead, it is necessary to constantly communicate with the system computer to request permission to travel, that is, to block the traveling section. Therefore, it is necessary to reduce the communication load by reducing the number of communications between the system computer and the automatic guided vehicle, and to evacuate the automated guided vehicle with a small number of communications.

[0004]

It is an object of the present invention to 1) reduce the number of block requests from the automatic guided vehicle to the system computer to reduce the communication load on the system computer. 2) reduce the evacuation mileage at the time of eviction. An object of the present invention is to make the automatic guided vehicle evacuate to a standby position having a high priority while shortening the length.

[0005]

According to the present invention, a number of automatic guided vehicles are arranged along a traveling route and controlled by a system computer to convey articles, and an empty automatic guided vehicle is provided on the traveling route with a priority. In the system in which the standby position is set to the standby position, the individual priority is given to each standby position, and the blocks of the travel route in the block range having the destination as the upper limit are set to the traveling first automatic guided vehicle. The second automatic guided vehicle waiting in the range is detected, a standby position outside the block range and having the shortest required traveling time is set as the first standby position, and It is checked whether or not there is a second standby position having a higher priority than the first standby position within a predetermined range in front of the first standby position. If there is a second standby position having a higher priority than the first standby position, the second standby position is set as a save destination. If the second standby position does not exist, the first standby position is set. The system computer is provided with an eviction means for evacuating the second automatic guided vehicle with the evacuated destination as a refuge destination. Here, the block range is, for example, the entire range up to the destination, a position before an intersection or a junction on the way to the destination, and the destination is the upper limit. The point of permission of the block after accepting the block request may be appropriately determined.
Also, the traveling route is the track of overhead traveling vehicles and ground traveling vehicles,
Alternatively, it may be a simple traveling route other than the track.

[0006]

According to the present invention, the first automatic guided vehicle traveling is requested to the system computer for blocks in the block range whose upper limit is the destination. Therefore, the first
The number of communication of block requests from the automatic guided vehicle to the system computer can be reduced, and the communication load on the system computer can be reduced. To perform the block, it is necessary to expel the second automatic guided vehicle waiting in the area from the area. For this reason, the system computer is provided with an expelling means, and the second automatic vehicle in the area is waiting in the area. Unmanned guided vehicles are detected and evacuated. The time when the eviction is performed is, for example, a time when the system computer receives or permits the block request, or a time when the first automatic guided vehicle enters a predetermined range behind the second automatic guided vehicle.

Here, each standby position is individually given a priority, and the eviction means sets a standby position where the second automatic guided vehicle can travel in the shortest required time outside the block range as a first standby position. It is checked whether or not there is a second standby position having a higher priority than the first standby position within a predetermined range ahead of the first standby position. If there is a second standby position having a higher priority than the first standby position, an instruction is given to perform a limp-home run to the second standby position, and if there is no second standby position having a higher priority, The evacuation traveling to the first standby position is instructed. For this reason, it is possible to make the unmanned guided vehicle evacuate to the standby position with high priority while keeping the traveling time near the shortest.

[0008]

1 to 7 show an embodiment. FIG. 1 shows the configuration of an automatic guided vehicle system according to an embodiment. A tracked or trackless traveling route 2 is provided inside a factory or a warehouse, and a number of automated guided vehicles 4 are provided along the traveling route 2. Travels, receives the transfer of articles from the station 6, and travels to another station 6 to transfer. For example, several to about 100 unmanned transport vehicles are provided, and a large number of stations 6 are also provided. The traveling for receiving the transfer of the article toward the station is referred to as loading traveling, and the traveling for unloading the transferred article at another station is referred to as unloading traveling.

The traveling route 2 is provided with a plurality of standby positions 8 indicated by ● in the figure, and the empty automatic guided vehicle stands by here. Standby position 8 is given an individual priority,
A high priority is given to a position facing a station where the number of times of transfer to the automatic guided vehicle is high, and traveling route 2 in FIG.
In the section where the station 6 is not arranged as in the upper part of the above, a high priority is given to the downstream side. The traveling route 2 in FIG. 1 is divided into six sections or the like, and a priority is independently assigned to each section so that the unmanned guided vehicles that are waiting excessively do not concentrate at a specific position. This is to allow an appropriate number of automatic guided vehicles to stand by in each section. The priority is, for example, data having a word length of about 2 to 8 bits.

Of course, if an escape line 10 is provided as shown in FIG. 1 and is evacuated here, an empty unmanned guided vehicle will not block the traveling route 2, but the space efficiency will be reduced. Therefore, at least a part of the automatic guided vehicle is evacuated on the original traveling route.

As shown in FIG. 2, the AGV 4 is managed by a system computer 20, and an AGV management unit 21 communicates with the AGV 4 by wire or wirelessly. Reference numeral 4 reports the current position, the execution status of the transfer command, and the like. The automatic guided vehicle management unit 21 assigns a transport command to each of the automatic guided vehicles 4, and designates a standby position when the transport command is completed. The standby position is determined by the eviction processing unit 27 described later.

Reference numeral 22 denotes a bus in the system computer 20 which receives a transfer command from a host computer, a control terminal, or the like (not shown) and reports the transfer result to the external input / output 2.
3, a transfer command management unit 24 for managing the transfer command received by the external input / output 23, an allocation unit 25 for allocating the transfer command to the automatic guided vehicle 4 and executing the same, and the like. 2
Reference numeral 6 denotes a route table management unit which stores the required travel time between the stations along the travel route 2 in, for example, a graph format.
Search for unmanned guided vehicles that can execute the transfer command in the shortest time. Then, the allocating unit 25 allocates and executes the transfer command to the automatic guided vehicle that can execute the transfer command in the shortest time.

The automatic guided vehicle 4 that travels by assigning a transfer command or the like requests, for example, the eviction processing unit 27 to block the section up to the destination. Blocking is permitted by permitting the vehicle to travel within the range, and the removal processing unit 27 is responsible for driving other unmanned guided vehicles within the block range out of this range. The required range of the block is preferably, in addition to the destination, an intersection, a junction, or just before a critical point such as a branch.

The eviction processing unit 27 receives a block request from the traveling automatic guided vehicle 4, detects an unmanned guided vehicle waiting within this range from the data of the automatic guided vehicle management unit 21, and detects Identify unmanned guided vehicles. Then, for example, the current position of the traveling automatic guided vehicle is detected, and when the interval with the automatic guided vehicle to be driven out approaches a predetermined value or less, a command is issued to drive out. The evacuation destination of the unmanned guided vehicle that has been kicked out is, for example, a position that can be run in the shortest time from the current position with reference to the route table managed by the route table management unit 26. It is determined and commanded through the automatic guided vehicle management unit 21.

On the route to the destination of the traveling automatic guided vehicle, for example, an automatic guided vehicle that is performing transfer of articles, charging, or the like is not an object to be kicked out. These are targeted for eviction after the transfer of the articles is completed or after the charging is completed, and until then, the block request is not fully or partially permitted. It should be noted that most of the unmanned guided vehicles that are being driven out are running unloaded. If the loading traveling is in progress, the allocating unit 25 assigns the transfer command to the unmanned guided vehicle on standby closer to the station to be loaded, so that the unmanned guided vehicle subsequent to the unmanned guided vehicle on standby is loaded. There is no need to kick out. Therefore, the destination of the traveling automatic guided vehicle is, in principle, a station for unloading.

The waiting position 8 in the block range is not a destination of refuge, and if there is a branch, the branch on the side different from the traveling automatic guided vehicle 4 is preferentially evacuated. If there is no branch from the condition that the vehicle can travel in the shortest time, the evacuation destination is immediately before the destination of the unmanned guided vehicle 4 on the driving side. However, it is preferable to evacuate to a higher priority standby position using eviction. Therefore, for example, if there is a higher priority standby position within a predetermined range from the nearest evacuation destination candidate, it is vacant. If so, extend the evacuation destination to that position. If the position is not empty, it moves to that position after waiting for the position to become empty.

FIGS. 3 to 7 show the contents of the eviction process and the control algorithm in the embodiment. FIG. 3 shows the simplest eviction process, and it is assumed that the automatic guided vehicle 4-1 is traveling to unload the station 6-1 (the standby position is 6). It is assumed that an unmanned guided vehicle 4-2 is waiting at the standby position 4. In this case, the automatic guided vehicle 4-1 is connected to the station 6-1.
In order to travel smoothly, the unmanned transport vehicle 4-1 in the block area may be driven out by blocking the unmanned transport vehicle 4-1 from the current position to the destination standby position 6 as a travel route. Therefore, the standby destination of the automatic guided vehicle 4-2 becomes the standby position 7 immediately before (immediately after) the blocked area, and when the automatic guided vehicle 4-1 finishes unloading at the station 6-1, two empty spaces are set. Of the automatic guided vehicle 4-2, 4-1 stops at the standby positions 6, 7. The two automatic guided vehicles 4-2 and 4-1 stand by at a continuous standby position, and can open the traveling route 10 to the maximum with a minimum evacuation distance.

FIG. 4 shows an eviction process taking priority into consideration. For example, it is assumed that the automatic guided vehicle 4-2 is waiting at the standby position 1 and the automatic guided vehicle 4-1 is traveling to unload at the station 6-1. The block area in this case is up to the standby position 4.
Each standby position has a priority, and an unmanned guided vehicle to be kicked out preferentially evacuates a standby position with a higher priority. For example, if the priority of the standby position 7 is high, there is a high possibility that the third automatic guided vehicle 4-3 is waiting here. When the priority is not considered, the automatic guided vehicle 4-2
Becomes new standby position, but if there is a standby position 7 having a higher priority in a predetermined range from here, for example, two or three vehicles at intervals of the standby position, the second automatic guided vehicle 4-2 will Attempt to wait in standby position 7. The standby position 7 is closed, so the immediately upstream position is set as a new standby position, and the standby position of the automatic guided vehicle 4-2 becomes 6. Automatic guided vehicle 4 in standby position 7
When -3 moves, the automatic guided vehicle 4-2 moves to the standby position 7.

The standby position that can be evacuated in the shortest time as described above is set as a basic candidate of the evacuating destination, and if there is a standby position with a higher priority within a predetermined range, the evacuating destination is changed to that. If that position is closed, the standby position before that position is set as a refuge destination, and the user waits for a standby position with a high priority to become available and moves there.
In this way, the automatic guided vehicle can be made to stand by at the standby position having a high priority by using the eviction.
If the priority is increased at a position facing a station where the number of times of loading the unmanned transport vehicle is large, the transport efficiency can be improved.

[0020] In addition, the fact that a plurality of automatic guided vehicles wait at a short interval has a problem of blocking a traveling route. Therefore, for example, if there is another unmanned guided vehicle ahead of a predetermined range from the standby position which can be evacuated in the shortest time, the position immediately after that is changed to the standby position. This change is also applied to the unmanned transport vehicle 4-1 which caused the ejection during traveling during unloading travel or the like. In the case of FIG. 4, the initial standby position of the unmanned transport vehicle 4-2 to be ejected is the standby position. 6, the automatic guided vehicle 4-
The standby position after the work 1 has completed the work at the station 6-1 is the standby position 5. Automatic guided vehicle 4 as described above
The standby position -2 is changed to the standby position 7 when it becomes available, and accordingly, the standby position of the automatic guided vehicle 4-1 is also changed to the standby position 6.

FIG. 5 shows that the traveling route 10 is a branch route 10.
The processing when branching to -1 and 10-2 is shown. The automatic guided vehicle 4-2 is waiting at the standby position 3 and is unloading and traveling toward the station 6-1.
Is approaching from behind. In addition, in order to show that the same processing as in FIG. 4 is performed here, the priority of the standby position 13 of the branch route 10-2 is set to be high, and the third automatic guided vehicle 4-3 is waiting here. And The waiting positions 1 to 5 are blocked in order to make the automatic guided vehicle 4-1 travel to the station 6-1. The automatic guided vehicle 4-2 waits with priority given to the side branched from the traveling route of the automatic guided vehicle 4-1. Therefore, the standby position 11 is a candidate for the standby position. Here, since the priority of the standby position 13 two vehicles ahead is high, the automatic guided vehicle 4-2 becomes the standby position 12, and moves to the standby position 13 when it becomes available. On the other hand, the automatic guided vehicle 4-1 is located at the station 6
After the vehicle travels to -1 and unloads it here, it stands by, for example, here. If there is a standby position with a higher priority within a predetermined range in front of it, it moves to it after the transfer is completed.

As an algorithm for giving priority to branching, for example, the shortest free standby position outside the block range as viewed from the automatic guided vehicle 4-2 may be detected. In this way, the branch route 10-2 has priority unless the standby position of the branch route 10-2 is already occupied by a large number of automatic guided vehicles. Instead of such a process, if there is a branch, it may be simply evacuated to the side of the unmanned transport vehicle that has been kicked out from the traveling route.

When there is a branch in the traveling route as shown in FIG. 5, there is another meaning in retreating to the side where the traveling automatic guided vehicle branches off from the traveling route. In the processing of FIG.
When there are many automatic guided vehicles traveling to the branch route 10-1,
The unmanned guided vehicle waiting on the way is evacuated to the branch route 10-2. As a result, branch route 1 with a large traveling amount
0-1 is removed from the evacuation destination, and branch route 1 with less travel distance
By using 0-2 as a temporary siding line, it is possible to open the branch route 10-1 with a large traveling amount.

FIGS. 6 and 7 show a control algorithm of the embodiment. FIG. 6 shows the entire process of one transport command. When the external input / output 23 receives the transport command, the allocating unit 25
The command is assigned to an automatic guided vehicle that can process the transfer command in the shortest time. Next, for example, the unmanned guided vehicle that has been assigned determines a traveling route, and reports this to the unmanned guided vehicle management unit 21. In addition, each automatic guided vehicle 4 reports the current position to the automatic guided vehicle management unit 21 every time the vehicle passes through the boundary between the standby positions and the like, or reports the current position at predetermined time intervals. For this reason, the current position of each AGV is known to the AGV management unit 21. Therefore, if there is an unmanned guided vehicle on standby in the traveling route to the destination of the traveling unmanned guided vehicle, the unmanned guided vehicle is subjected to the eviction subroutine shown in FIG. The actual eviction may be started, for example, when the traveling automatic guided vehicle and the standby automatic guided vehicle approach each other within a predetermined interval or less.

When an automatic guided vehicle within a predetermined range in front is stopped for unloading, loading, or the like, or stopped for charging, it is not driven out but a subsequent automatic guided vehicle is used. Will stop and wait. Therefore, the block request is permitted only up to the position immediately after the automatic guided vehicle stopped for loading or the like in the front. When the traveling route of the traveling automatic guided vehicle is secured by the eviction subroutine, after reaching the destination, for example, articles are transferred from the automatic guided vehicle to the station, and the transport instruction is terminated. Here, the ejection is shown as being associated with the processing of the transfer command, but the ejection is generally performed when the unmanned transport vehicle waiting on the traveling route of the subsequent unmanned transport vehicle is blocked.

FIG. 7 shows the contents of the eviction subroutine. For example, in the case of FIGS. 3 to 5, for example, a traveling route to a destination of the traveling automatic guided vehicle 4-1 is blocked.
Next, it is detected whether or not another automatic guided vehicle is present in the block area. If there is an unmanned guided vehicle waiting in the block range, the presence or absence of a branch in the blocked range is checked. If there is a branch, the side that drives out the unmanned guided vehicle to be kicked out by the algorithm described above. Branch to a different side from the automated guided vehicle. If there is no branch, the waiting automatic guided vehicle is evacuated to a position immediately before (outside flow) outside the block range. In this way, a temporary refuge destination of the unmanned guided vehicle on standby is determined. And, for example, 3
If there is a standby position with a higher priority due to a standby position ahead of the platform, the evacuation destination is changed to that position. If a third automatic guided vehicle is waiting at that position, the evacuation position of the automated guided vehicle to be evacuated immediately upstream is changed, and a position with a higher priority is vacated, and one position is moved there. Advance the standby position. In this way, the unmanned guided vehicle on standby is preferentially deployed at the standby position with a high priority, and subsequent transportation work is facilitated. Further, if there is a third automatic guided vehicle within the range of, for example, three automatic guided vehicles from the evacuation destination that can be moved in the shortest time, the evacuation destination is changed (front justified) immediately after the third automatic guided vehicle, Widen the available travel routes.

If another unmanned guided vehicle is on standby until the temporary evacuating position, a similar eviction process is performed on the unmanned guided vehicle. As described above, the eviction process is not only applied to the unmanned guided vehicle during unloading and traveling, but is generally applied to the unmanned guided vehicle during traveling. In other words, the eviction subroutine of FIG. 7 is not only an eviction process for securing the traveling route of the unmanned transport vehicle that is originally traveling, but also a eviction process for securing the traveling route of the automated guided vehicle that has been expulsed thereby. Is also performed recursively. Although a specific example has been described in the embodiment, the present invention is not limited to this.

[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 diagram showing basic eviction processing in the embodiment.

FIG. 4 is a diagram illustrating a leading justification process in the embodiment.

FIG. 5 is a diagram showing an eviction process when there is a branch in the embodiment.

FIG. 6 is a flowchart showing an outline of processing of a transfer command in the embodiment.

FIG. 7 is a flowchart illustrating an eviction process according to the embodiment.

[Explanation of symbols]

 2 traveling route 4 automatic guided vehicle 6 station 8 standby position 20 system computer 21 automatic guided vehicle management unit 22 bus 23 external input / output 24 transfer command management unit 25 allocation unit 26 route table management unit 27 eviction processing unit

Claims (1)

(57) [Claims] An automatic guided vehicle is arranged along a traveling route and controlled by a system computer to convey articles, and an empty automated guided vehicle stands by at a standby position provided on the traveling route. In the system, each of the waiting positions is given an individual priority, and the traveling first automatic guided vehicle requests the system computer to request a block of a travel route in a block range having the destination as an upper limit. The second automatic guided vehicle in standby is detected, the standby position outside the block range and having the shortest required travel time is set as the first standby position, and the second automatic guided vehicle is set in the predetermined range ahead of the first standby position and the second automatic guided vehicle is set in the predetermined range. It is checked whether there is a second standby position having a higher priority than the first standby position, and a priority is set over the first standby position. When there is a high second standby position, the second standby position is set as a save destination. When the second standby position does not exist, the first standby position is set as a save destination. An automatic guided vehicle system, characterized in that an ejecting means for evacuating the second automatic guided vehicle is provided in the system computer.