Automated transport system

Abstract

When controlling the movement of multiple automated transport devices using a self-position estimation method based on marker reading, it is possible to avoid collisions and overtaking of other automated transport devices, regardless of the movement route, enabling smooth and safe transport. [Solution] This automated transport system 10 comprises a plurality of markers 11 (11a), a plurality of automated transport devices 12 (12a, 12b) capable of moving between the markers 11 while reading the positional information of the markers 11 and recognizing their own position, and a control device 13 (13b) capable of setting a movement route R (R1) for each automated transport device 12 and controlling the movement of each automated transport device 12 along the set movement route R. If the set movement route R includes a movement route R1 in which the same automated transport device 12a passes a marker 11a at a predetermined position twice, the control device 13b restricts the movement of other automated transport devices 12b toward the marker 11a at a predetermined position until the same automated transport device 12a has passed the marker 11a at a predetermined position twice.

Description

Technical Field

[0001] The present invention relates to an automatic conveyance system, and particularly to a system for controlling the movement of a plurality of automatic conveyance devices.

Background Art

[0002] In recent years, in manufacturing sites of various industrial products including automobiles, the spread of automatic conveyance devices called AGVs has been promoted from the perspective of labor-saving in anticipation of a future decrease in the working population, or from the perspective of improving the safety of workers.

[0003] This type of automatic conveyance device has various types of movement methods, and the so-called path guidance method is the mainstream. In the automatic conveyance device according to this method, a guiding line such as a magnetic tape or an optical tape is arranged on the floor along the path, and the automatic conveyance device moves along the guiding line while detecting magnetism or reflected light from the guiding line with a corresponding sensor (for example, refer to Patent Document 1).

[0004] On the other hand, recently, from the perspectives of reducing installation costs and facilitating layout changes, automatic conveyance devices using a self-position estimation method utilizing image recognition have begun to spread. In the automatic conveyance device according to this method, elements displaying position information such as two-dimensional codes represented by QR codes (registered trademarks) and AR markers (hereinafter simply referred to as markers) are arranged at predetermined positions on the floor, for example, at positions that become grid points, and the automatic conveyance device estimates its own position by reading the position information of the marker with a camera or the like, and then autonomously moves aiming at the next marker to be headed for (for example, refer to Patent Document 2).

Prior Art Documents

Patent Documents

[0005] `

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] Incidentally, in the actual operation of this type of automated guided vehicle (AGV) system, it is not uncommon to move multiple AGVs simultaneously from the standpoint of efficient operation. However, when such operation is carried out, the following problems may arise. Specifically, in a self-position estimation method using marker reading, when a predetermined AGV moves along a pre-set travel route, a method can be considered in which, triggered by reading a marker on the travel route, other AGVs are set (controlled) to move toward the marker that was passed immediately before the trigger marker. If such a method is adopted, even if the travel route of the preceding AGV and the travel route of the following AGV overlap, there is no problem as long as all AGVs move along a one-way travel route.

[0007] On the other hand, consider a scenario where, for example, a preceding automated guided vehicle (AGV) starts moving along a predetermined route in one direction, deviates from the one-way route midway to load items to be transported, moves to a work area, loads the items, and then returns to the original one-way route. In such a case, the preceding AGV might pass the marker closest to the work area, move to the work area along a guide line, complete a predetermined task (e.g., loading the items to be transported) in the work area, and then return to the marker closest to the work area. In this case, if the AGV reads a marker for confirming the stopping position in the work area, this reading will trigger another AGV to start moving towards the marker it passed immediately before the trigger marker, i.e., the marker located at the entrance of the guide line. This creates a risk of collision between the preceding AGV and a following AGV that has moved to the marker closest to the work area when the preceding AGV returns along the guide line. Alternatively, if a trailing automated transport device reaches the nearest marker before the leading automated transport device has completed its back-and-forth movement along the guide line and returned to that marker, the trailing automated transport device may overtake the leading automated transport device.

[0008] In view of the above circumstances, this specification aims to provide an automated transport system that can transport goods smoothly and safely by avoiding collisions and overtaking of other automated transport devices, regardless of the travel route, when multiple automated transport devices are controlled by a self-position estimation method based on marker reading. [Means for solving the problem]

[0009] The aforementioned problem is solved by the automated transport system according to the present invention. Specifically, the automated transport system comprises a plurality of position detection markers placed on the floor surface, a plurality of automated transport devices capable of moving between the markers while reading the position information of the markers and recognizing their own position, and a control device capable of setting a movement route for each automated transport device and controlling the movement of each automated transport device along the set movement route. The control device is characterized in that, if the set movement route includes a movement route in which the same automated transport device passes a marker at a predetermined position twice, it restricts the movement of other automated transport devices toward a marker at a predetermined position until the same automated transport device has passed the marker at the predetermined position twice.

[0010] In the automated transport system according to the present invention, if the movement route of each automated transport device set by the control device includes a route in which the same automated transport device passes a predetermined marker twice, the system restricts the movement of other automated transport devices toward the predetermined marker until the same automated transport device has passed the predetermined marker twice. By controlling the movement of each automated transport device in this way, as described above, even if a predetermined automated transport device deviates from a one-way movement route, moves from the predetermined marker to the work area, and then returns to the predetermined marker to rejoin the one-way movement route, it is possible to avoid a situation in which a following automated transport device mistakenly moves toward the predetermined marker and collides with it. Therefore, even when multiple automated transport devices are transported at the same time and some of their movement routes overlap, smooth and safe transport is possible.

[0011] Furthermore, in the conveying device according to the present invention, the control device may release the movement restriction on other automatic conveying devices when the same automatic conveying device has passed a marker at a predetermined position twice and has moved to the next marker after the marker at the predetermined position.

[0012] As mentioned above, when restricting the movement of other automated guided vehicles (AGVs) toward a predetermined marker until the same AGV has passed that marker twice, the timing of releasing this restriction is crucial. For example, the restriction on other AGVs could be released after a predetermined amount of time has elapsed since the same AGV passed the marker twice. However, if for some reason the AGV is unable to move toward the next marker (for example, if the preceding AGV has malfunctioned and stopped at the next marker), this could lead to the following AGV moving toward the still-stopped preceding AGV. In contrast, with this configuration, if the restriction on other AGVs moving toward the predetermined marker is released only after the same AGV has passed the marker twice and moved to the marker following the predetermined marker, it is possible to ensure that the preceding AGV is not present at the predetermined marker and will not return, allowing the following AGV to move toward the predetermined marker. Therefore, collisions between automated transport devices can be avoided more reliably, making it possible to safely carry out transport using multiple automated transport devices.

[0013] Furthermore, in the automated transport system according to the present invention, when the control device receives position information obtained by reading a marker from a predetermined automated transport device, it may permit the movement of another automated transport device toward the marker that the predetermined automated transport device has just passed. The predetermined automated transport device may transmit the position information obtained by reading the marker at the predetermined position to the control device when it first passes the marker at the predetermined position, and may not transmit all position information obtained by reading markers between the first and second passes of the marker at the predetermined position to the control device, but may transmit the position information obtained by reading the next marker after the marker at the predetermined position to the control device.

[0014] With this configuration, the control unit only needs to determine whether each automated transport device is allowed to move (whether to restrict or release movement restrictions) based solely on the self-position information transmitted from each automated transport device. Therefore, despite the extremely simple control, it is possible to move each automated transport device smoothly and safely, even when the same automated transport device takes a complex movement route, such as passing a predetermined marker twice before moving to the next marker. Furthermore, because the control is extremely simple, it is easy to accommodate changes in movement routes, making it possible to change the layout at a low cost.

[0015] Furthermore, in the automated transport system according to the present invention, a guide line capable of guiding the automated transport device may be provided on the floor surface between the work area of ​​a predetermined automated transport device and the marker closest to the work area among a plurality of markers, and the movement route may be set so that the marker closest to the work area is designated as the marker of the predetermined position, and the automated transport device includes back-and-forth movement along the guide line.

[0016] In this type of automated transport system, speed is more important than accuracy when moving towards the work area, making a self-position estimation method using marker reading suitable. On the other hand, due to the nature of automated transport systems, introduction (loading) into the work area often involves predetermined positioning. Therefore, by moving the automated transport system along a guide line to reach the work area, the automated transport system can be accurately positioned at a predetermined location within the work area. Thus, this configuration makes it possible to transport objects quickly while accurately performing tasks such as loading and unloading. [Effects of the Invention]

[0017] As described above, according to the automated transport system of the present invention, when controlling the movement of multiple automated transport devices using a self-position estimation method based on marker reading, it is possible to avoid collisions and overtaking of other automated transport devices, regardless of the movement route, and to carry out transport smoothly and safely. [Brief explanation of the drawing]

[0018] [Figure 1] It is a plan view showing the overall configuration of an automatic conveyance system according to an embodiment of the present invention. [Figure 2] It is a flowchart showing the control flow by the overall control unit shown in FIG. 1. [Figure 3] It is a flowchart showing the control flow by the individual control unit of each automatic conveyance device shown in FIG. 1. [Figure 4] It is a diagram showing an example of the usage mode of the automatic conveyance system shown in FIG. 1, and shows a state where the preceding automatic conveyance device has moved to the marker closest to the corresponding first work area. [Figure 5] It is a diagram showing an example of the usage mode of the automatic conveyance system shown in FIG. 1, and shows a state where the preceding automatic conveyance device has reached a predetermined position within the corresponding first work area. [Figure 6] It is a diagram showing an example of the usage mode of the automatic conveyance system shown in FIG. 1, and shows a state where the preceding automatic conveyance device has moved from the corresponding first work area to the marker closest to the work area. [Figure 7] It is a diagram showing an example of the usage mode of the automatic conveyance system shown in FIG. 1, and shows a state where the preceding automatic conveyance device has moved to the marker next to the marker at the predetermined position. [Figure 8] It is a diagram showing an example of the usage mode of the automatic conveyance system shown in FIG. 1, and shows a state where the preceding automatic conveyance device has moved to the marker closest to the corresponding second work area. [Figure 9] It is a diagram showing an example of the usage mode of the automatic conveyance system shown in FIG. 1, and shows a state where the preceding automatic conveyance device has reached a predetermined position within the corresponding second work area.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, the content of the automatic conveyance system according to an embodiment of the present invention will be described based on the drawings.

[0020] Figure 1 shows a plan view of the overall configuration of an automated transport system 10 according to one embodiment of the present invention. This automated transport system 10 mainly comprises a plurality of markers 11, a plurality of automated transport devices 12, and a control device 13. In this embodiment, the control device 13 consists of individual control units 13a mounted on each automated transport device 12 and a central control unit 13b that controls all of the plurality of automated transport devices 12 in a unified manner. The automated transport system 10 further comprises one or more guide lines 15 extending toward the work area 14. After describing the details of each element below, an example of how the automated transport system 10 according to this configuration is used will be described.

[0021] Markers 11 are used to estimate the self-position of the automated transport device 12 and are placed on the floor surface. In this embodiment, multiple markers 11 are placed at positions that serve as grid points within a predetermined area on the floor surface. In this case, the distance between adjacent markers 11, 11 (in this embodiment, the distance of one side constituting the grid) is set to a constant size (for example, 1 m).

[0022] In this embodiment, any type of marker 11 can be used, as long as it displays location information in a readable format by an information reading unit (not shown) such as a camera, magnetic sensor, or laser sensor provided on the automatic transport device 12.

[0023] The automated transport device 12 reads positional information of markers 11 placed on the floor surface, estimates its own position based on the read positional information, and is capable of autonomously moving toward the target marker 11. It has a reading unit (not shown), a drive unit (not shown), and an individual control unit 13a that controls the drive of the drive unit. The reading unit is, for example, a camera that is pointed downward or diagonally forward and is configured to read positional information of markers 11 located in the forward position in the direction of travel or directly below the automated transport device 12. The reading unit in the above configuration may be operating in a state where it can always read. The individual control unit 13a estimates the position of the automated transport device 12 from the positional information read by the reading unit and can control the drive unit so that the automated transport device 12 moves toward the next target marker 11 along the estimated position and a movement route R set in advance by the overall control unit 13b. The drive unit has, for example, a motor and a drive wheel driven by the motor, and drives the motor to rotate the drive wheel based on a command from the individual control unit 13a. This enables the automatic transport device 12 to move forward, backward, stop, or rotate (including rotating in place). In addition, the individual control unit 13a, in principle, transmits the position information read by the reading unit to the central control unit 13b when it reads the position of the marker 11. On the other hand, under certain conditions, such as when the marker 11 to be read is a marker 11 specific to each automatic transport device 12, i.e., a marker 11a at a predetermined position according to the present invention, the read position information is not transmitted to the central control unit 13b. Details will be described later.

[0024] The central control unit 13b is capable of centrally managing the movement of multiple target automatic transport devices 12, setting a movement route R for each automatic transport device 12 and controlling the movement of each automatic transport device 12 along the set movement route R. In this embodiment, the control device 13 sets the movement route R for each automatic transport device 12 as described above and transmits the set movement route R to each automatic transport device 12.

[0025] For example, if there are two automated transport devices 12 to be controlled, and the transported items are loaded in different work areas 14 (first work area 14a) and unloaded in a common work area 14 (second work area 14b), the movement routes R1 and R2 of each automated transport device 12a and 12b are set as follows. First, the movement route R(R1) transmitted to the leading automated transport device 12a of the two automated transport devices 12 is set to move from the waiting position shown in Figure 1 to the marker 11 one to the right, then to the marker 11 three positions down, then downward along the guide line 15, stop at the marker 11 in the first work area 14a to load the transported items (not shown), then return to the marker 11 closest to the first work area 14a along the guide line 15 that was just passed, then move in one direction to the marker 11 four positions to the right, then to the marker 11 four positions up, then move left along the guide line 15 to reach the second work area 14b. Furthermore, the movement route R(R2) transmitted to the following automatic transport device 12b is set in this embodiment to move from the waiting position shown in Figure 1 to the marker 11 one position to the right, then to the marker 11 four positions down, then to the marker 11 two positions to the right, then move downward along the guide line 15, stop at the marker 11 in the first work area 14a to load the items to be transported, then return to the marker 11 closest to the first work area 14a along the guide line 15 that was just passed, then move in one direction to the marker 11 one position to the right, then to the marker 11 four positions up, then move left along the guide line 15 to reach the second work area 14b.

[0026] Furthermore, the central control unit 13b permits or restricts each automated transport device 12 to move toward the next target marker 11 on its respective movement route R, based on the position information of each automated transport device 12 (which marker 11 it is located on) transmitted from each automated transport device 12 to the central control unit 13b. Upon receiving permission to move from the central control unit 13b, each automated transport device 12 either starts moving toward the next marker 11 or waits at its current position.

[0027] As described above, Figures 2 and 3 show an example of the control flow when the central control unit 13b manages the movement of each automated transport device 12. Figure 2 is a flowchart showing the control flow of the central control unit 13b, and Figure 3 is a flowchart showing the control flow by the individual control units 13a of each automated transport device 12. First, the central control unit 13b receives the latest updated position information whenever each automated transport device 12 updates its position information, and determines whether to allow each automated transport device 12 to move to the next target marker 11 based on the received position information. Specifically, it determines whether there is another automated transport device 12 on the next target marker 11 for each automated transport device 12 (step S11 in Figure 2).

[0028] If the control unit 13b determines that no other automated transport device 12 is present on the next target marker 11, it sends a signal to the target automated transport device 12 to allow it to move (step S12). On the other hand, if the control unit 13b determines that another automated transport device 12 is present, it refrains from sending a signal to allow the target automated transport device 12 to wait at its current position (step S13).

[0029] In this embodiment, when the central control unit 13b sets the movement route R for each automatic transport device 12, the movement of the preceding automatic transport device 12 to the marker 11 on route R is reserved preferentially. In Figure 1, the marker 11 enclosed by a single solid line frame is reserved preferentially for the preceding automatic transport device 12a. This movement reservation information is shared by all automatic transport devices 12, including the following automatic transport device 12b. This movement reservation information is released by sending a signal to each automatic transport device 12 that permits movement. In other words, sending a signal to each automatic transport device 12 that permits movement in step S12 is equivalent to releasing the movement reservation information of the preceding automatic transport device 12a. Therefore, the following automatic transport device 12b will not move to the marker 11 with the movement reservation information (a single solid rectangular frame in Figure 1) unless the movement reservation information of the preceding automatic transport device 12a is released, and will instead be controlled to wait on the marker 11 immediately preceding it.

[0030] Steps S11 to S13 above are repeated until all automated transport devices 12 have moved to their final position on their respective travel route R (in this case, the waiting position shown in Figure 1) (step S14).

[0031] On the other hand, each automated transport device 12 estimates its current position each time it reads the position information of a marker 11 with its reading unit, identifies the next target marker 11 from its set movement route R, and determines whether it has received a signal from the control unit 13b that permits movement toward the next target marker 11 (step S21 in Figure 3). If it has received a signal that permits movement, it starts moving toward the next target marker 11 (step S22). On the other hand, in this embodiment, if it has not received a signal that permits movement, the movement reservation information of the preceding automated transport device 12a is not canceled until it receives a movement permission signal (sent by the control unit 13b), so it waits at its current position, that is, the position where it most recently read a marker 11, until it receives a movement permission signal (step S23).

[0032] Furthermore, when the reading unit reads the position information of the marker 11, the individual control unit 13a of each automatic transport device 12 decides whether or not to transmit the position information to the central control unit 13b before determining whether or not a movement permission signal has been received. That is, referring to the upper part of Figure 3, it is determined whether or not the read position information is the same as the position information obtained when the device first passes a predetermined marker 11 (indicated by reference numeral 11a in Figure 1) that it passes twice along its own movement route R (step S24). If it is determined that the position information is the same as the position information obtained when the device first passes the predetermined marker 11a, the read position information is transmitted to the central control unit 13b (step S25).

[0033] On the other hand, if it is determined that the position information is not obtained when the marker 11a at the predetermined position is first passed, then it is determined whether the position information is obtained between the first and second passes of the marker 11a at the predetermined position (step S26). If it is determined that the read position information is obtained between the first and second passes of the marker 11a at the predetermined position, in the case of Figure 1, it is determined that the position information is obtained by reading the stop marker 11b located in the first work area 14a, or the position information is obtained when the marker 11a at the predetermined position is passed for the second time, then the read position information is not transmitted to the control unit 13b and the process proceeds to the next step S21 (step S27). As a result, when the automatic transport device 12 is positioned on the stop marker 11b, the control unit 13b recognizes that the automatic transport device 12 is still positioned on the previous marker 11 (the marker 11a at the predetermined position) on the movement route R.

[0034] Alternatively, if the location information obtained by reading the marker 11 is not applicable under any of the above conditions, the obtained location information is transmitted to the control unit 13b (step S25).

[0035] Each automated transport device 12 repeats steps S21 to S27 until it moves to its final position on its own travel route R (in this case, the waiting position shown in Figure 1) (step S28).

[0036] In this embodiment, the work area 14 has a first work area 14a for loading items transported by the automatic transport device 12, and a second work area 14b for unloading. Of these, the first work area 14a is provided in three locations, and the second work area 14b is provided in one location. Of course, this is just one example. The content of the work in the work area 14 is arbitrary, and the number of work areas 14 can also be set arbitrarily.

[0037] The guide line 15 is for enabling the automated transport device 12 to travel in a path-guided manner, and is positioned between the work area 14 and the marker 11 closest to the work area 14. In this case, the guide line 15 is preferably configured so that the automated transport device 12 can detect the guide line 15 on the marker 11 closest to the work area 14. In this embodiment, a marker 11 (indicated by reference numeral 11b in Figure 1) is positioned within the work area 14 close to the guide line 15. This marker 11b is a marker for detecting the stopping position of the automated transport device 12, and the automated transport device 12 can stop when it reads this marker 11b after moving along the guide line 15.

[0038] The type of guide wire 15 is, in principle, arbitrary, and known guide materials such as magnetic tape or optical tape can be used. Furthermore, it is important to provide a guide wire 15 reading unit according to the type of guide wire 15 (guide material) adopted. For example, if the guide wire 15 is optical tape, the marker 11 and the guide wire 15 may be readable using a common reading unit such as a camera.

[0039] Next, an example of how the automated transport system 10 with the above configuration is used will be explained, focusing on the control system.

[0040] First, as shown in Figure 1, we assume a scenario where two automated transport devices 12a and 12b load goods in different work areas 14 (first work areas 14a, 14a) and unload the transported goods in a common work area 14 (second work area 14b). In this case, the central control unit 13b sets a predetermined movement route R (R1, R2) for each automated transport device 12 and transmits the set movement route R to each automated transport device 12. Furthermore, if movement routes R1 and R2 overlap, movement reservation information is attached to the corresponding marker 11, allowing the preceding automated transport device 12a to move preferentially along its own movement route R1. In Figure 1, movement reservation information is attached to all markers 11 on the movement route R1 of the preceding automated transport device 12a. For the trailing automatic transport device 12b, in the portion that does not overlap with the travel route R1 of the preceding automatic transport device 12a, travel reservation information is attached to the marker 11 on the travel route R2 (only the marker 11 to the right of the trailing automatic transport device 12b).

[0041] Upon receiving the movement route R1, the preceding automatic transport device 12a begins moving to the next marker 11 along the movement route R1, following the control flow shown in Figure 3. That is, in the state shown in Figure 1, it reads the standby position marker 11, estimates its own position to be the position shown in Figure 1, and determines whether there is a signal to permit movement to the next target marker 11 (the marker 11 to the right of the preceding automatic transport device 12a in Figure 1) along the movement route R1 (step S21 in Figure 3). At this point, there are no other automatic transport devices 12 on the marker 11, and it is not a specific marker 11a that the preceding automatic transport device 12a passes twice, so it receives a movement permission signal from the control unit 13b (step S12) and begins moving to the next marker 11 (step S22).

[0042] Meanwhile, after a predetermined time has elapsed, the trailing automatic transport device 12b begins to move along its own movement route R2. Here, as shown in Figure 1, if at least a portion of the movement route R2 of the trailing automatic transport device 12b overlaps with the movement route R1 of the preceding automatic transport device 12a, the movement of the trailing automatic transport device 12b along its movement route R2 is restricted by the movement reservation information along the movement route R1 of the preceding automatic transport device 12a (steps S13, S23). In this case, the trailing automatic transport device 12b is permitted to move to the marker 11 immediately preceding the latest marker 11 read by the preceding automatic transport device 12a (steps S12, S22). In the state shown in Figure 4, the trailing automatic transport device 12b is permitted to move to the marker 11 immediately above the marker 11 where the preceding automatic transport device 12a is located.

[0043] As described above, both automatic transport devices 12a and 12b move along their respective movement routes R1 and R2. As shown in Figure 4, when the leading automatic transport device 12a reaches the marker 11a at a predetermined position, the leading automatic transport device 12a changes its movement mode and moves along the guide line 15 to reach the first work area 14a (see Figure 5). At this time, a stop marker 11b is provided within the first work area 14a, and the predetermined work (loading of goods) in the first work area 14a is performed with the leading automatic transport device 12a stopped on this stop marker 11b. In this case, the reading unit of the leading automatic transport device 12a reads the position information of the stop marker 11b, but according to the control flow shown in Figure 3, the position information obtained by reading the stop marker 11b is not transmitted to the main control unit 13b (step S27). Furthermore, the position information read when the marker 11a closest to the first work area 14a is passed twice is not transmitted to the control unit 13b (both in step S27). Therefore, after the preceding automatic transport device 12a has completed its predetermined work in the first work area 14a, until it passes the marker 11a at the predetermined position twice via the guide line 15, the following automatic transport device 12b waits at the marker 11 just before the marker 11a at the predetermined position that the preceding automatic transport device 12a passes twice (in Figure 1, the marker 11 just above the marker 11a at the predetermined position).

[0044] Then, as shown in Figure 7, when the leading automatic transport device 12a passes the predetermined marker 11a twice and moves to the next marker 11 (the marker 11a to the right), the control unit 13b releases the movement reservation information for the leading automatic transport device 12a and permits the trailing automatic transport device 12b to move toward the predetermined marker 11a (step S12). At this time, the leftmost predetermined marker 11a is newly assigned movement reservation information for the trailing automatic transport device 12b (in Figure 7, a double rectangular frame is drawn to surround the corresponding marker 11a).

[0045] Subsequently, the preceding automated transport device 12a moves in one direction along the movement route R1 to the marker 11 at the far right, and then to the marker four positions above it (see Figure 8). After that, it moves to the left along the guide line 15 and stops at the stopping marker 11b in the second work area 14b (see Figure 9). After completing the predetermined work (unloading work), it continues to move along its own movement route R1 and moves to the final position of the movement route R1 (i.e., the waiting position shown in Figure 1), thereby ending the transport operation described above.

[0046] Similarly, the following automated transport device 12b moves along its own movement route R2 to a predetermined marker 11a (the third marker from the left) which it passes twice, and then moves along the guide line 15 to the first work area 14a located below (see Figure 8). After stopping at a stop marker 11b located within the first work area 14a and performing the loading operation of the goods (see Figure 9), it returns via the guide line 15 to the rightmost predetermined marker 11a, moves in one direction along its own movement route R2 to the marker 11 one position to the right, and then to the marker 11 four positions above, and then moves to the left along the guide line 15 and stops at a stop marker 11b in the second work area 14b (figure 1 is omitted). After completing the predetermined operation (unloading operation), it continues to move along its own movement route R2 and moves to the final position of the movement route R2 (i.e., the waiting position shown in Figure 1) to complete the transport operation described above. In this manner, the transport operations of the multiple automated transport devices 12a and 12b are carried out.

[0047] As described above, in the automated transport system 10 according to this embodiment, if the movement route R set by the control device 13 for each automated transport device 12 includes a movement route R1 in which the same automated transport device 12a passes a predetermined marker 11a twice, the movement of other automated transport devices 12b toward the predetermined marker 11a is restricted until the same automated transport device 12a has passed the predetermined marker 11a twice (see Figures 5 to 7). By controlling the movement of each automated transport device 12 in this way, even if a predetermined automated transport device 12a deviates from the one-way movement route R1, moves from the predetermined marker 11a to the work area 14, and then returns to the predetermined marker 11a to rejoin the one-way movement route R1, it is possible to avoid a situation in which a following automated transport device 12b mistakenly moves toward the predetermined marker 11a and collides with it. Therefore, even when multiple automated transport devices 12a and 12b are moved at the same time and parts of the movement routes R1 and R2 overlap, it is possible to transport them smoothly and safely.

[0048] Furthermore, in this embodiment, if the restriction on other automatic transport devices 12b to move to the predetermined marker 11a is released when the same automatic transport device 12a has passed the predetermined marker 11a twice and has moved to the next marker 11, it is possible to move the trailing automatic transport device 12b toward the predetermined marker 11a while ensuring that the preceding automatic transport device 12a is not present on the predetermined marker 11a and will not return. Thus, collisions between automatic transport devices 12a and 12b can be avoided more reliably, and transport by multiple automatic transport devices 12a and 12b can be carried out safely.

[0049] Furthermore, in this embodiment, when the control unit 13b of the control device 13 receives position information obtained by reading a marker 11 from a predetermined automatic transport device 12a, it permits the movement of another automatic transport device 12b toward the marker 11 that the predetermined automatic transport device 12a has just passed. In this case, the predetermined automatic transport device 12a transmits the position information obtained by reading the marker 11a at the predetermined position to the control unit 13b when it first passes the marker 11a at the predetermined position, but does not transmit all position information obtained by reading the marker 11 between the first and second passes of the marker 11a at the predetermined position to the control unit 13b, and instead transmits the position information obtained by reading the next marker 11 after the marker 11a at the predetermined position to the control unit 13b.

[0050] By dividing the control role between the individual control unit 13a and the central control unit 13b, which function as the control device 13, the central control unit 13b, which manages the movement of multiple automated transport devices 12, only needs to determine whether each automated transport device 12 is allowed to move (whether movement is restricted and whether the restriction is lifted) based solely on the self-position information transmitted from each automated transport device 12. Therefore, even with extremely simple control, it is possible to move each automated transport device 12 smoothly and safely, even when the same automated transport device 12 takes a complex movement route R, such as passing a predetermined marker 11a twice before moving to the next marker 11. Furthermore, because the control is extremely simple, it is easy to respond to changes in the movement route R, making it possible to respond to layout changes at low cost.

[0051] In addition, as in this embodiment, when the automatic transport device 12 is moved to the work area 14 by a guide line 15 to improve positional accuracy, and a stop marker 11b is placed within the work area 14, by defining the control modes of the individual control unit 13a and the overall control unit 13b as described above, it is not necessary to transmit positional information obtained by reading the stop marker 11b. Therefore, predetermined work can be performed accurately while reliably avoiding collisions.

[0052] Although one embodiment of the present invention has been described above, the automated transport system according to the present invention may also adopt configurations other than those described above, without departing from the spirit of the invention.

[0053] For example, in the above embodiment, the example given is that the restriction on movement to the marker 11a at a predetermined position for other automatic transport devices 12b is released when the same automatic transport device 12a has passed the marker 11a at a predetermined position twice and has moved to the next marker 11 after the marker 11a at the predetermined position, but of course, it is not limited to this. For example, the restriction on movement to the marker 11a at a predetermined position for other automatic transport devices 12b may be released when a predetermined time has elapsed after the same automatic transport device 12a has passed the marker 11a at a predetermined position twice. Alternatively, the restriction on movement to the marker 11a at a predetermined position for other automatic transport devices 12b may be released when the same automatic transport device 12a has passed the marker 11a at a predetermined position twice and has moved a predetermined distance toward the next marker 11, [Explanation of Symbols]

[0054] 10. Automated transport system 11 Markers 11a Marker at a designated position 11b Stop marker 12, 12a, 12b Automatic conveying device 13 Control device 13a Individual control unit 13b General Control Unit 14,14a,14a Work Area 15 Guide wire R, R1, R2 Travel Route

Claims

1. Multiple markers for position detection placed on the floor surface, Multiple automated transport devices capable of moving between the markers while reading the positional information of the markers and recognizing their own position, An automated transport system comprising a control device capable of setting a movement route for each of the automated transport devices and controlling the movement of each automated transport device along the set movement route, The control device is characterized in that, if the set movement route includes a movement route in which the same automatic transport device passes the marker at a predetermined position twice, it restricts the movement of other automatic transport devices toward the marker at a predetermined position until the same automatic transport device has passed the marker at the predetermined position twice.

2. The automatic transport system according to claim 1, wherein the control device releases the movement restriction on the other automatic transport device when the same automatic transport device has passed the marker at the predetermined position twice and has moved to the next marker after the marker at the predetermined position.

3. When the control device receives position information obtained by reading the marker from the predetermined automatic transport device, it permits the movement of the other automatic transport device toward the marker that the predetermined automatic transport device passed immediately before. The predetermined automatic transport device transmits position information obtained by reading the marker at the predetermined position when it first passes over the marker at the predetermined position to the control device. The automated transport system according to claim 1, wherein all position information obtained by reading the marker at a predetermined position between the first time the marker is passed and the second time the marker is passed is not transmitted to the control device, and position information obtained by reading the next marker after the marker at the predetermined position is transmitted to the control device.

4. Guide lines capable of guiding the automatic transport device are provided on the floor surface between the work area of ​​the predetermined automatic transport device and the marker closest to the work area among the plurality of markers. The automated transport system according to any one of claims 1 to 3, wherein the transport route is set to include the reciprocating movement of the automated transport device along the guide line, with the marker closest to the work area being designated as the marker at the predetermined position.

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