Conveying system

Abstract

Provided is a conveyance system that can heighten conveyance efficiency, even when applied to systems having tracks with various configurations. The present invention is a conveyance system (1) for conveying articles by causing a plurality of conveyance vehicles to travel, characterized by comprising a plurality of conveyance vehicles (2) for conveying articles (M) to be conveyed, and a controller (6) that causes the plurality of conveyance vehicles (2) to travel by assigning conveyance instructions to each of the plurality of conveyance vehicles (2), and further characterized in that according to an execution situation of the conveyance instructions, the controller (6) puts a portion of the plurality of conveyance vehicles (2) in a standby state, in which conveyance instructions cannot be assigned thereto.

Description

Technical Field

[0001] The present invention relates to a transport system, and more particularly to a transport system that transports articles by running a plurality of transport vehicles.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2003-233422 (Patent Document 1) describes a transport system and its control method. This transport system includes an annular track, a plurality of transport vehicles running on this track, a station for loading / unloading articles onto / from the transport vehicles, and a standby station for waiting for the transport vehicles. Further, the transport system includes a transport control controller, and each transport vehicle runs on the track based on a command from this transport control controller.

[0003] Furthermore, a transport instruction is input from a higher-level computer to the transport control controller, and based on this transport instruction, a transport instruction table that stores the transport source station (departure point) and the transport destination station (destination) is created. The transport control controller runs the transport vehicles based on this transport instruction table and executes the input transport instruction. Further, the transport control controller determines the number of transport vehicles to be operated based on the number of transport instructions. That is, if the number of transport vehicles on the track is too large relative to the number of articles to be transported, the transport vehicles may compete with each other at branch points, merging points, stations, etc. on the track, resulting in waiting times and a decrease in transport efficiency. In the transport system described in Patent Document 1, it is attempted to achieve rapid and efficient transport by determining the number of transport vehicles to be operated based on the number of transport instructions.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the invention described in Patent Document 1 has a problem in that, depending on the transport system to which it is applied, it may not be possible to sufficiently improve transport efficiency. In other words, in the invention described in Patent Document 1, the number of transport vehicles to be operated is determined based on the number of transport instructions, but the number of transport instructions does not necessarily reflect the load on the transport system, and it is not possible to operate an appropriate number of transport vehicles. That is, even if the number of transport instructions is small, if each instruction is a long-distance transport instruction or a transport instruction that requires long-distance travel, the load on the system will be large, and even if the number of transport instructions is large, if each instruction is a short-distance transport instruction or an instruction that can be completed in a short time, the load on the system will be small. For example, in the invention described in Patent Document 1, the transport vehicles are configured to run on a circular track, but depending on the configuration of the track on which the transport vehicles run, the total number of transport vehicles, the arrangement of stations, etc., it may not be possible to sufficiently improve transport efficiency.

[0006] Therefore, the present invention aims to provide a conveying system that can improve conveying efficiency even when applied to systems with various configurations. [Means for solving the problem]

[0007] To solve the above-mentioned problems, the present invention provides a method by having multiple transport vehicles travel by , to be processed items Between multiple processing units A transport system comprising multiple transport vehicles for transporting goods to be transported, and a controller that operates the multiple transport vehicles by assigning transport commands to each of the multiple transport vehicles, wherein the controller puts some of the multiple transport vehicles into a standby state where it cannot be assigned a transport command, depending on the execution status of the transport commands. At the same time, the transport vehicles that were set to standby are moved to the standby area and stopped, and the controller sets the standby area near the processing unit that has stopped operating. It is characterized by the following.

[0008] In the present invention configured as described above, transport commands are assigned to multiple transport vehicles for transporting the goods to be transported, thereby causing each transport vehicle to operate. Depending on the execution status of the transport commands, the controller puts some of the multiple transport vehicles into a standby state where they cannot be assigned transport commands.

[0009] According to the present invention configured in this way, the controller puts the transport vehicles into a standby state according to the execution status of the transport command, so that the number of transport vehicles to be operated can be appropriately set. As a result, the transport efficiency of the transport system can be improved.

[0010] According to the present invention configured in this way, since the transport vehicles in standby mode are moved to the standby area, it is possible to prevent the transport vehicles in standby mode from interfering with the transport vehicles in operation, thereby improving the transport efficiency of the transport system.

[0011] In the present invention, preferably, the controller sets a track with infrequent traffic among the tracks on which the transport vehicles can travel as a waiting area, and moves the transport vehicles that are in a waiting state to this waiting area.

[0012] With the present invention configured in this way, since a waiting area is set on a track on which the transport vehicle can travel, the transport vehicle can be moved to the waiting area simply by sending a control signal from the controller, and the transport vehicle can be easily transitioned from an operational state to a standby state, or from a standby state to an operational state.

[0013] In the present invention, preferably, the transport vehicle is configured to run on an onboard battery, and multiple charging stations are provided on the track on which the transport vehicle can travel, and the battery can be charged by stopping at these charging stations, and the controller sets the charging station with the lowest utilization rate among the multiple charging stations as a standby area.

[0014] According to the present invention configured in this way, charging stations with low utilization rates are set in the standby area, thus preventing standby transport vehicles from interfering with operational transport vehicles.

[0015] In the present invention, preferably, the transport vehicle is configured to run on an onboard battery, and when the transport vehicle is in standby mode, it is set to a low power consumption mode. According to the present invention configured in this way, the transport vehicle, when in standby mode, is set to a low power consumption mode, thereby suppressing the energy consumption of the transport vehicle while it is in standby mode.

[0016] In the present invention, preferably, the controller rotates the transport vehicles in the standby state at predetermined intervals, even if there is no change in the number of transport vehicles in the standby state. According to the present invention configured in this way, even if the number of transport vehicles in standby mode does not change, the transport vehicles in standby mode are rotated at predetermined intervals. This avoids a situation where some transport vehicles remain in standby mode for a long period of time while others continue to operate for a long period of time, and makes it possible to equalize the load on each transport vehicle.

[0017] In the present invention, preferably, the transport vehicle is configured to run on an onboard battery, and the controller preferentially selects a transport vehicle with a high number of battery charging cycles and puts it into standby mode.

[0018] According to the present invention configured in this way, transport vehicles with a high number of battery charging cycles are preferentially selected and put into standby mode. This makes it possible to equalize the number of charging cycles for the batteries installed in each transport vehicle, preventing battery degradation from being unevenly distributed among some transport vehicles.

[0019] In the present invention, preferably, the track on which the transport vehicle travels is formed in a grid pattern, and the transport vehicle is configured to be able to go straight, turn right, and turn left at each intersection of the grid-like track.

[0020] According to the present invention configured as described above, in a conveyance system in which a carrier travels on a lattice-shaped track and can go straight, turn right, and turn left at each intersection of the track, an appropriate number of carriers can be operated, and the conveyance efficiency can be improved.

Advantages of the Invention

[0021] According to the conveyance system of the present invention, the conveyance efficiency can be increased even when applied to systems having various configurations.

Brief Description of the Drawings

[0022] [Figure 1] It is a perspective view of the conveyance system according to an embodiment of the present invention as seen from above. [Figure 2] It is a perspective view showing a carrier provided in the conveyance system according to an embodiment of the present invention. [Figure 3] It is a block diagram of the entire conveyance system according to an embodiment of the present invention. [Figure 4] It is a flowchart showing the processing by a controller in the conveyance system according to an embodiment of the present invention. [Figure 5] It is a plan view schematically showing an example of a semiconductor manufacturing factory to which the conveyance system according to an embodiment of the present invention is applied. [Figure 6] It is an example of a heat map showing the traffic volume of carriers in the semiconductor manufacturing factory shown in FIG. 5.

Modes for Carrying Out the Invention

[0023] Next, a conveyance system according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 is a perspective view from above of a transport system according to an embodiment of the present invention. Figure 2 is a perspective view showing a transport vehicle provided in the transport system according to an embodiment of the present invention. In this embodiment, the present invention is applied to a transport system that transports items such as hoops containing semiconductor wafers and reticle pods containing reticles within a cleanroom of a semiconductor manufacturing plant.

[0024] As shown in Figure 1, the transport system 1 according to an embodiment of the present invention comprises a transport vehicle 2 for transporting items to be transported, a plurality of rails 4 for forming a track on which the transport vehicle 2 travels, and a controller 6 that causes the transport vehicle to move by sending a transport command signal to the transport vehicle. Although only one transport vehicle 2 is shown in Figure 1, the transport system 1 according to this embodiment is equipped with a plurality of transport vehicles 2, and the controller 6 is configured to cause a plurality of transport vehicles 2 to move simultaneously by sending a transport command signal to each of the transport vehicles 2.

[0025] Rails 4 are beam-like members suspended from the ceiling of a building such as a cleanroom, and are provided in large numbers at equal intervals in a horizontal plane, extending in a first direction D1 and in a second direction perpendicular to the first direction. Each transport vehicle 2 is configured to travel along rails 4 while suspended below rails 4 between two adjacent rails 4. Thus, the transport system 1 of this embodiment is an overhead transport vehicle in which the transport vehicle 2 travels along a track formed by rails 4 suspended from the ceiling. That is, a track extending in the first direction D1 is formed between two adjacent rails extending in the first direction D1, and a track extending in the second direction D2 is formed between rails extending in the second direction D2, and each transport vehicle 2 travels along these tracks. Therefore, a grid-like track on which each transport vehicle 2 can travel is formed by the large number of rails 4 extending in the first direction D1 and the second direction D2.

[0026] Thus, the transport system 1 of this embodiment is a so-called "grid system" in which the transport vehicles 2 travel along a grid-like track, and at each intersection of the track in the first direction D1 and the track in the second direction D2, each transport vehicle 2 is configured to move straight, turn right, and turn left. Therefore, by traveling along the track, each transport vehicle 2 can move to any location within the area where the grid-like track is provided. In this embodiment, the grid-like track formed by each rail 4 is configured such that the first direction D1 and the second direction D2 intersect at right angles to each other, but the angle between the first direction D1 and the second direction D2 does not necessarily have to be a right angle.

[0027] Next, as shown in Figure 2, the transport vehicle 2 has a main body 10, four running wheels 12 attached to the upper side of the main body 10, and a transfer device 14 attached to the lower side of the main body 10. The transport vehicle 2 is suspended between the rails 4 and is configured to travel along the track formed by the rails 4 by rotating each running wheel 12. The transport vehicle 2 is also configured to be able to suspend an item M to be transported below it, and by traveling along the track with the item M suspended, the item M can be transported to the desired location. In this embodiment, since the transport system 1 is applied to a semiconductor manufacturing plant, the transport vehicle 2 transports, for example, a hoop, which is an item M, from one processing device 22a (Figure 5) to the next processing device 22g (Figure 5).

[0028] The main body 10 of the transport vehicle 2 is a rectangular prism-shaped housing with a square shape when viewed from above, and the length of one side of the square is smaller than the distance between each rail 4. As a result, the transport vehicle 2 fits between two adjacent rails 4, and a transport vehicle 2 traveling on one track can pass another transport vehicle 2 traveling on an adjacent track. In addition, as shown in Figure 2, the main body 10 has a battery 16 and a circuit board 18 built inside.

[0029] The battery 16 is configured to supply power to drive the four wheels 12 on the transport vehicle 2 and to operate the circuit board 18. Furthermore, as will be described later, the transport system 1 is equipped with a charging station 24 (Figure 5), which is configured to charge the batteries 16 of each transport vehicle 2. Specifically, a predetermined charging position Cp (Figure 5) is set on the track on which the transport vehicle 2 can travel, near the charging station 24, and by stopping the transport vehicle 2 at the charging position for a predetermined time, the batteries 16 of the transport vehicle 2 on the track can be charged.

[0030] The circuit board 18 is built into the main body 10 and is configured to control the operation of the transport vehicle 2. The circuit board 18 is equipped with a transmit / receive circuit (not shown) for sending and receiving control signals to and from the controller 6, and a drive circuit (not shown) for a motor (not shown) for driving the transport wheels 12. Specifically, these circuits consist of a microprocessor, input / output interface circuits, memory, etc., mounted on the circuit board 18, and these operate according to the software stored in the memory, powered by the battery 16.

[0031] Next, the running wheels 12 are wheels provided at the four corners of the upper surface of the main body 10, and these running wheels 12 engage with each rail 4 extending on both sides of the main body 10, thereby suspending the transport vehicle 2 below the rails 4. Each running wheel 12 is rotationally driven by a motor (not shown) provided on the transport vehicle 2, and as a result, the transport vehicle 2 travels along the track while suspended below each rail 4.

[0032] Furthermore, each of the wheels 12 is configured to rotate around an axis A extending vertically, thereby allowing the transport vehicle 2 to change its direction of travel. That is, in the state shown in Figure 2, the transport vehicle 2 can travel on a track extending in the second direction D2, and from this state, by rotating each of the wheels 12 90 degrees around axis A, it becomes possible to travel on a track extending in the first direction D1. Therefore, when changing the direction of travel of the transport vehicle 2, the transport vehicle 2 is stopped at the intersection of the track in the first direction D1 and the track in the second direction D2 (the point where the transport vehicle 2 is located in Figure 1). In this state, by rotating each of the wheels 12 90 degrees around axis A, the transport vehicle 2 can travel in a different direction.

[0033] Next, the transfer device 14 is located on the underside of the main body 10 of the transport vehicle 2. By operating this transfer device 14, the items M to be transported can be loaded onto or unloaded from the transport vehicle 2.

[0034] Specifically, in this embodiment, the transfer device 14 comprises a lifting drive unit 14a and an article holding unit 14b provided below the lifting drive unit 14a. The lifting drive unit 14a is composed of a hoist (not shown) and is configured to raise and lower the article holding unit 14b by suspending it with a wire (not shown). On the other hand, the article holding unit 14b is equipped with a chuck (not shown) having a movable claw (not shown), and the article M can be suspended by grasping a part of the article M to be transported with this chuck.

[0035] In this embodiment, when loading an item M onto the transport vehicle 2, the transport vehicle 2 is stopped above the item M to be transported, and in this state, the lifting drive unit 14a is activated to lower the item holding unit 14b. Next, with the item holding unit 14b lowered to a predetermined position, the chuck (not shown) of the item holding unit 14b is activated to hold the item M. After the item M is held by the item holding unit 14b, the lifting drive unit 14a is activated to lift the item holding unit 14b together with the item M to a predetermined position, thereby loading the item M onto the transport vehicle 2. In this state, the item M can be transported by driving the transport vehicle 2 to the destination. When the transport vehicle 2 reaches the destination, the lifting drive unit 14a is activated to lower the item holding unit 14b together with the item M to a predetermined position, and the item M is released from being held by the chuck (not shown). This allows the item M that was loaded onto the transport vehicle 2 to be unloaded.

[0036] Next, the configuration and operation of the controller 6 will be explained with reference to Figures 3 through 5. Figure 3 is a block diagram of the entire transport system 1 according to an embodiment of the present invention, including the controller 6. Figure 4 is a flowchart of the processing in the controller 6. Figure 5 is a schematic plan view showing an example of a semiconductor manufacturing plant to which the transport system 1 according to an embodiment of the present invention is applied.

[0037] As shown in Figure 3, the controller 6 includes a request signal input unit 6a, an operating rate calculation unit 6b that calculates the operating rate of the transport vehicles 2 according to the execution status of the transport command, a transport vehicle determination unit 6c that determines the transport vehicle based on the calculated operating rate, and a command signal transmission unit 6d that transmits a command signal to the determined transport vehicle. Specifically, the controller 6 consists of a microprocessor, memory, interface circuitry, transceivers, and software to operate them (the above are not shown).

[0038] The request signal input unit 6a is configured to receive transport request signals sent from the higher-level controller 20. In this embodiment, the higher-level controller 20 is a controller that oversees the entire semiconductor manufacturing process and outputs instructions for transporting items M such as reticle pods and hoops that need to be transported in the semiconductor manufacturing process to the controller 6 as transport request signals.

[0039] Here, the transport request signal is a signal that instructs which point on the track that the transport vehicle 2 can travel on to transport the item M to which point. For example, the transport request signal is a signal that instructs the transport to transport the hoop containing the semiconductor wafer that has been processed in the first processing device 22a (Figure 5) from the load port of the first processing device 22a to the load port of the second processing device 22g (Figure 5) that will perform the next processing step. In this embodiment, the upper controller 20 and the controller 6 are configured separately, but they may be configured as a single unit.

[0040] Next, the calculation of the operating rate by the operating rate calculation unit 6b in Figure 3 will be explained with reference to Figure 5. Figure 5 is a schematic plan view of an example of a semiconductor manufacturing plant to which the transport system 1 is applied, and the parallel vertical and horizontal lines drawn in a grid pattern represent the tracks that the transport vehicle 2 can travel on. Also in Figure 5, the rectangles drawn with dashed lines represent the processing units 22a to 22g installed on the floor of the semiconductor manufacturing plant. Furthermore, in Figure 5, the rectangle drawn with dashed lines represents a charging station 24 installed on the floor, and charging positions Cp1 to Cp3, indicated by ◎, are provided on the track near this charging station 24. By stopping the transport vehicle 2 at any of these charging positions, the battery 16 mounted on the transport vehicle 2 can be charged non-contact via a coupler (not shown). Also, in the example shown in Figure 5, a waiting area S is set in the lower left part. Note that in Figure 5, multiple transport vehicles are indicated by the labels 2a to 2d to distinguish them.

[0041] The operating rate calculation unit 6b (Figure 3) is configured to calculate the percentage of transport vehicles 2 that are operating to execute transport request signals. For example, in Figure 5, transport vehicle 2a transports an item M located at point P1 near processing unit 22a in the semiconductor manufacturing plant to point P2 near processing unit 22g by traveling along the track indicated by the arrow, in accordance with a transport request signal. Transport vehicle 2b also transports an item M located at point P3 near processing unit 22d to point P4 near processing unit 22e by traveling along the track indicated by the arrow, in accordance with another transport request signal. Meanwhile, transport vehicle 2d is stopped in the waiting area S and is in a standby state. Transport vehicle 2c is not in a standby state, but has not been assigned a transport command signal and is stopped.

[0042] Thus, in this embodiment, the transport vehicles are classified into those in a standby state (transport vehicle 2d) and those in a non-standby state (transport vehicles 2a, 2b, 2c). The non-standby transport vehicles are classified into those that have been assigned a transport command signal and are actually performing transport (transport vehicles 2a, 2b) and those that have not been assigned a transport command signal (transport vehicle 2c). In this embodiment, the utilization rate is defined as the number of transport vehicles actually performing transport divided by the number of transport vehicles in a non-standby state, and the utilization rate calculation unit 6b is configured to calculate the utilization rate. Furthermore, although the utilization rate changes moment by moment depending on the transport execution status of each transport vehicle 2, the utilization rate calculation unit 6b is configured to calculate the average utilization rate over a predetermined period of time.

[0043] Furthermore, transport vehicles 2 that are actually performing transport can be classified into three types: transport vehicles 2 heading towards the item M to load the item M to be transported, transport vehicles 2 traveling toward the destination with the item M loaded, and transport vehicles 2 that have transported the item M to the destination and are traveling to a position where the next transport can be easily performed. In this embodiment, the utilization rate is calculated by considering all of these transport vehicles 2 as transport vehicles 2 that are performing transport. As a modified example, the utilization rate can also be calculated by considering only the transport vehicles 2 that are traveling toward the destination with the item M loaded, and the transport vehicles 2 that have transported the item M to the destination and are traveling to a position where the next transport can be easily performed, as transport vehicles 2 that are performing transport.

[0044] Next, the transport vehicle determination unit 6c determines, based on the average operating rate over a predetermined time calculated by the operating rate calculation unit 6b, how many of the transport vehicles 2 controllable by the controller 6 will be in an operational state (non-standby state) to which transport commands can be assigned, and how many will be in a standby state (non-operational state) to which transport commands cannot be assigned. In other words, if the number of transport vehicles 2 actually in operation is too large compared to the amount of transport commands, congestion of transport vehicles 2 may occur on the track, which may actually reduce transport efficiency. Also, if there are many transport vehicles 2 in an operational state that are not actually transporting anything, power will be wasted. As an example, the number of transport vehicles 2 to be in an operational state is determined so that the operating rate, which is the status of transport command execution, is 70% to 80%, and the remaining transport vehicles 2 will be in a standby state (non-operational state).

[0045] Furthermore, the transport vehicle determination unit 6c is configured to determine which of the transport vehicles 2 should be in operation and which should be in standby mode. In other words, if only some of the transport vehicles 2 are always in operation, those transport vehicles 2 will wear out quickly, shortening the service life of the entire transport system 1. Also, transport vehicles 2 may malfunction if they remain in standby mode for a long period of time. For this reason, in this embodiment, even if the number of transport vehicles 2 that should be in operation does not change, the transport vehicles in standby mode are rotated at predetermined intervals. This prevents some transport vehicles 2 from always being in operation or always being in standby mode, and prevents the load from being unevenly distributed among some of the transport vehicles 2.

[0046] Furthermore, the transport vehicle selection unit 6c prioritizes selecting transport vehicles 2 whose mounted batteries 16 have been charged many times and puts them into standby mode. That is, since the transport vehicles 2 run on the power of the batteries 16, the batteries 16 of transport vehicles 2 that have carried a lot of goods will be charged many times. By prioritizing the standby mode for transport vehicles 2 with many charge cycles, it is possible to put transport vehicles 2 with fewer charge cycles and less transport volume into operation, thereby making the degree of battery degradation of all transport vehicles 2 closer to being equal.

[0047] Next, the command signal transmission unit 6d is configured to transmit command signals to each transport vehicle 2 and to cause each transport vehicle 2 to travel as needed. Specifically, the command signal transmission unit 6d sends a transport command signal to the transport vehicles 2 that have been set to an operational state by the transport vehicle determination unit 6c, causing them to perform transport based on the transport request signal input from the higher-level controller 20. The command signal transmission unit 6d also issues a command to the transport vehicles 2 that have been set to a standby state by the transport vehicle determination unit 6c to move to the standby area S, causing the transport vehicles 2 to move to the standby area S (Figure 5) and then stop. In this embodiment, the standby area S is not a fixed, dedicated area, but is set on a portion of the track that the transport vehicles 2 can travel on, and is changed as appropriate according to the operating status of the transport system 1.

[0048] Furthermore, when the transport vehicle 2 is moved to the standby area S and stopped, it is set to a low power consumption mode, and the consumption of power charged in the battery 16 is suppressed. In other words, although the transport vehicle 2 set to low power consumption mode can be restarted in response to a signal transmitted from the command signal transmission unit 6d of the controller 6, it is in a sleep state, and the power consumed by the circuit board 18, etc. is suppressed. For this reason, the transport vehicle 2 in standby mode requires a predetermined amount of time to respond to a command signal from the command signal transmission unit 6d before it can actually transport, and its state is different from that of a transport vehicle 2 that is stopped in an operational state.

[0049] Next, we will explain the operation of controller 6 with reference to Figure 4. The process shown in the flowchart in Figure 4 is repeatedly executed by the controller 6 while the transport system 1 of this embodiment is in operation. First, in step S1 of Figure 4, a transport request signal is input from the upper-level controller 20 to the request signal input unit 6a of the controller 6. Also in step S1, the execution status of the transport command is input to the controller 6.

[0050] Next, in step S2, the utilization rate of the transport vehicles 2 is calculated by the utilization rate calculation unit 6b based on the execution status of the transport command input in step S1. In this embodiment, transport vehicles 2 that are heading toward the item M to load the item M to be transported, transport vehicles 2 that are traveling toward the destination with the item M loaded, and transport vehicles 2 that have transported the item M to the destination and are traveling to a position where the next transport can be easily performed are defined as transport vehicles 2 that are currently performing transport. The utilization rate is calculated by dividing the total number of these transport vehicles 2 by the number of transport vehicles 2 that are not in a standby state. Furthermore, the average value of multiple utilization rates calculated at predetermined time intervals in the most recent past is calculated as the utilization rate per hour.

[0051] Furthermore, in step S3, the number of transport vehicles 2 to be in an operational state (not in a standby state) is determined according to the hourly utilization rate calculated in step S2. As described above, in this embodiment, the number of transport vehicles 2 to be in an operational state is determined so that the utilization rate is 70-80%, that is, on average, about 70-80% of the transport vehicles 2 that are in an operational state are actually carrying goods M and traveling. This makes it possible to respond quickly to short-term increases in workload and improve transport efficiency while suppressing power consumption.

[0052] Next, in step S4, it is determined whether the number of operational transport vehicles 2 determined in step S3 has increased compared to the current number of operational vehicles. If the number of operational vehicles has increased, the process in the flowchart proceeds to step S5; otherwise, it proceeds to step S7. In step S5, the transport vehicle determination unit 6c selects the number of transport vehicles 2 to be put into operation from the transport vehicles 2 in standby mode, equal to the number of vehicles added. In this embodiment, the transport vehicle determination unit 6c selects the transport vehicles 2 from the transport vehicles 2 in standby mode in order of the number of past charging cycles of the installed battery 16, and puts them into operation mode.

[0053] Next, in step S6, the command signal transmission unit 6d sends a start command signal to the transport vehicle 2 that has been set to the operating state, returning it from the low power consumption mode to the operating state. In the example shown in Figure 5, the command signal transmission unit 6d of the controller 6 sends a start command signal to the transport vehicle 2d that was in standby mode and stopped in the standby area S, returning it to the operating state. Also, if a new transport request signal was input in step S1, a transport command signal is sent to the transport vehicle 2 that has been set to the operating state in order to execute it. For example, in the example shown in Figure 5, a transport command signal is sent to the transport vehicle 2c that is stopped in the operating state, and transport corresponding to the new transport request signal is executed. Furthermore, if all transport vehicles 2 that are in the operating state are in the process of transporting goods M, a transport command signal is sent to the transport vehicle that has just returned to the operating state.

[0054] On the other hand, in step S4, if it is determined that the number of operational transport vehicles 2 determined in step S3 has not increased compared to the current number of operational vehicles, the process in the flowchart proceeds to step S7. In step S7, it is determined whether the number of operational transport vehicles 2 has decreased. If the number of operational transport vehicles 2 determined in step S3 has decreased compared to the current number of operational vehicles, the process in the flowchart proceeds to step S8. In step S8, the transport vehicle determination unit 6c selects a transport vehicle 2 to change from operational to standby. In this embodiment, among the transport vehicles 2 in operational status, the transport vehicles 2 with the most battery 16 charge cycles are selected in descending order and set to standby. This makes the operational status of each transport vehicle 2 more uniform.

[0055] Next, in step S6, the command signal transmission unit 6d sends a command signal to the newly selected transport vehicle 2 in standby mode, moves it to the standby area S, stops the transport vehicle 2 in the standby area S, and then sets it to low power consumption mode. If the newly selected transport vehicle 2 is transporting goods M, it is moved to the standby area S after the transport is completed. In the example shown in Figure 5, the standby area S is set as an area of ​​the track that the transport vehicle 2 can travel on, where the traffic volume of the transport vehicle 2 is low.

[0056] In this embodiment, the waiting area S is not set in a special track area that is not used by the transport vehicle 2 to transport the goods M, but rather in a part of the area that the transport vehicle 2 can also use to transport the goods M. Therefore, the position and size of the waiting area S can be changed as appropriate depending on the operating status of the transport system 1. This prevents a certain area from being constantly occupied to provide the waiting area S, and allows for effective use of the area that the transport vehicle 2 can travel in. For example, if there is a processing unit 22 in a semiconductor manufacturing plant that is stopped from operation due to maintenance or the like, the waiting area S can be set in the track area near that processing unit 22.

[0057] Next, with reference to Figure 6, the setting of the waiting area S in this embodiment will be explained. Figure 6 is an example of a heat map showing the traffic volume of transport vehicles 2 within the semiconductor manufacturing plant shown in Figure 5. The heat map shown in Figure 6 is a map that shows the frequency with which transport vehicles 2 traveled along a given path within a predetermined period, indicated by the intensity of the colors. Paths with a high frequency of transport vehicle 2 travel are shown in darker colors, while paths with a low frequency of travel are shown in lighter colors.

[0058] As shown in Figure 6, tracks near the center of the semiconductor manufacturing plant and tracks adjacent to frequently used processing equipment 22 are shown in darker colors due to the high frequency of transport vehicle 2 travel on them. On the other hand, tracks in the corners of the semiconductor manufacturing plant and in areas where processing equipment 22 is not installed are shown in lighter colors due to the low frequency of transport vehicle 2 travel on them. Therefore, tracks that are less frequently used by transport vehicle 2 are occupied by transport vehicle 2 for a smaller proportion of time. In this way, even if a standby transport vehicle 2 is stopped in a section of the track where the proportion of occupied time is low, it does not interfere with the movement of transport vehicles 2 that are in operation, and does not reduce the transport efficiency of the transport system 1. For this reason, in the example shown in Figure 6, the standby area S is set in the area of ​​the track where the proportion of occupied time by transport vehicle 2 is low and which is shown in lighter colors on the heat map.

[0059] Alternatively, as shown in Figure 5, charging positions Cp1 to Cp3 are provided near the charging station 24 in the semiconductor manufacturing plant, and the charging position with the lowest utilization rate among these charging positions can be designated as the standby area S. In the example shown in Figure 6, of the three charging positions, charging position Cp1 has a low utilization rate, and the proportion of time occupied at charging position Cp1 is small. By designating such a charging position with a low utilization rate as the standby area S, the transport vehicle 2 can be kept in standby mode without hindering its movement, and the transport vehicle 2 can also be charged while in standby mode.

[0060] Furthermore, in this embodiment, the waiting area is set in an area on the track that can also be used by the transport vehicle to transport goods. However, depending on the configuration of the transport system, the present invention can also be configured so that the waiting area is a dedicated area where the transport vehicle does not travel for the purpose of transporting goods. Moreover, if there is a low probability of the system being in operation for a long period of time, the present invention can also be configured so that some or all of the transport vehicles set to the waiting state are moved out of the track on which the transport vehicle can travel.

[0061] On the other hand, in step S7 of Figure 4, if the number of operational transport vehicles 2 determined in step S3 has not decreased compared to the current number of operational vehicles (i.e., the number of operational transport vehicles 2 has not changed), the process in the flowchart proceeds to step S9. In step S9, the transport vehicle determination unit 6c determines whether or not it is necessary to replace the transport vehicle 2 that is in standby mode. If it is necessary to replace the transport vehicle 2 that is in standby mode, the process in the flowchart proceeds to step S10; otherwise, it proceeds to step S6.

[0062] In other words, if the number of operational transport vehicles 2 determined in step S3 is the same as the current number of operational vehicles, the transport system 1 can continue to operate without switching any standby transport vehicles 2 to operational status or switching operational transport vehicles 2 to standby status. However, if the number of operational vehicles remains unchanged for a long period of time, and only some transport vehicles 2 continue to operate, the load will be concentrated on those transport vehicles 2, causing them to deteriorate more quickly. Therefore, in the transport system 1 of this embodiment, the controller 6 rotates the transport vehicles in standby status at predetermined intervals, even if there is no change in the number of operational transport vehicles 2 (and therefore no change in the number of standby transport vehicles 2). In this embodiment, if the number of standby transport vehicles 2 remains constant for a predetermined period of time or longer, it is determined that it is necessary to rotate the standby transport vehicles 2.

[0063] If it is determined that a change of transport vehicle 2 in standby mode is necessary, the process proceeds to step S10, where the transport vehicle determination unit 6c changes the transport vehicle 2 in standby mode. In this embodiment, the transport vehicles 2 are changed using a toggle system. For example, if there are 12 transport vehicles 2 numbered No. 1 to No. 12, and four of them (No. 1 to No. 4) remain in standby mode for a predetermined time, transport vehicles 2 No. 1 to 4 are made operational, and transport vehicles 2 No. 5 to 8 are made into standby mode. Furthermore, if transport vehicles 2 No. 5 to 8 remain in standby mode for a predetermined time, transport vehicles 2 No. 9 to 12 are then made into standby mode. In this way, even if the number of transport vehicles 2 in standby mode does not change, the transport vehicle determination unit 6c changes the transport vehicles 2 in standby mode at predetermined intervals, ensuring that the load is distributed evenly among the transport vehicles 2.

[0064] According to the transport system 1 of the embodiment of the present invention, the controller 6 puts the transport vehicles 2 into a standby state according to the execution status of the transport command, so that the number of transport vehicles to be operated can be appropriately set. As a result, the transport efficiency of the transport system 1 can be significantly improved.

[0065] Furthermore, according to the transport system 1 of this embodiment, the transport vehicle 2 that is in standby mode is moved to the standby area S (Figure 5), so that the transport vehicle 2 in standby mode does not interfere with the transport vehicle 2 that is in operation, and the transport efficiency of the transport system 1 can be improved.

[0066] Furthermore, according to the transport system 1 of this embodiment, since the waiting area S is set on a track that the transport vehicle 2 can travel on, the transport vehicle 2 can be easily transitioned from an operational state to a standby state, or from a standby state to an operational state, simply by sending a control signal from the controller 6. Also, since the track with the lowest proportion of occupied time is set as the waiting area S based on the heat map (Figure 6), the waiting area S can be set according to the operational state of the transport system 1. As a result, there is no need to always prepare a dedicated area for a fixed waiting area, and space can be used effectively.

[0067] Furthermore, according to the transport system 1 of this embodiment, the charging position Cp corresponding to the charging station 24 with a low utilization rate is set in the standby area S, so that the standby transport vehicle 2 does not interfere with the transport vehicle 2 in operation. In addition, by setting the charging position Cp in the standby area S, the standby transport vehicle 2 can be charged, reducing the number of times the transport vehicle 2 in operation needs to be charged, and thus improving transport efficiency.

[0068] Furthermore, according to the transport system 1 of this embodiment, the transport vehicle 2, which is in standby mode, is set to a low power consumption mode, so that the energy consumption of the transport vehicle 2 while in standby mode can be suppressed, and the energy efficiency of the transport system 1 can be improved.

[0069] Furthermore, according to the transport system 1 of this embodiment, even if there is no change in the number of transport vehicles 2 in standby mode, the transport vehicles in standby mode are rotated at predetermined intervals (step S10 in Figure 4), so that a situation in which some transport vehicles 2 are in standby mode for a long period of time while others continue to operate for a long period of time can be avoided, and the load on each transport vehicle 2 can be made more even.

[0070] Furthermore, according to the transport system 1 of this embodiment, the transport vehicle 2 with a high number of battery 16 charge cycles is preferentially selected and put into standby mode (step S8 in Figure 4). This makes it possible to equalize the number of charge cycles of the batteries 16 installed in each transport vehicle 2, and prevents the degradation of the batteries 16 from being unevenly distributed among some transport vehicles 2.

[0071] Although embodiments of the present invention have been described above, various modifications can be made to the embodiments described above. In particular, in the embodiments described above, the present invention was applied to a grid system in which the tracks of the transport vehicles were formed in a grid shape, but the present invention can also be applied to a transport system in which each transport vehicle travels along a fixed track. Furthermore, in the embodiments described above, the transport system consisted of an overhead hoist transport in which the transport vehicles travel along a track provided on the ceiling, but the present invention can be applied to various transport systems, such as a transport system using an automated guided vehicle (AGV) or a rail-type automated guided vehicle (RGV) in which the transport vehicles travel along a track (passage) on the floor. In addition, in the embodiments described above, the track on which each transport vehicle travels was made up of rails, but the track on which each transport vehicle travels does not have to be made up of physical members such as "rails". [Explanation of symbols]

[0072] 1. Conveying System 2 Transport vehicles 4 rails 6 Controllers 6a Request signal input section 6b Operating Rate Calculation Unit 6c Transport vehicle determination section 6d Command signal transmission unit 10 Main body 12 running wheels 14 Transfer equipment 14a Lifting drive unit 14b Article holding part 16 batteries 18 Circuit boards 20 High-end controllers 22 Processing Unit 24 charging stations

Claims

1. A transport system that transports items to be processed between multiple processing devices by having multiple transport vehicles run on a track, Multiple transport vehicles for transporting the goods to be transported, The system includes a controller that drives the multiple transport vehicles by assigning transport commands to each of the multiple transport vehicles, The controller, depending on the execution status of the transport command, puts some of the transport vehicles among the multiple transport vehicles into a standby state where they cannot be assigned the transport command, and moves the transport vehicles in the standby state to the standby area and stops them. The above controller is a transport system characterized by setting the standby area in a track near a processing unit that has stopped operating.

2. The transport system according to claim 1, wherein the controller sets a track with infrequent transport vehicle traffic as a waiting area among the tracks on which the transport vehicle can travel, and moves the transport vehicle in a waiting state to this waiting area.

3. The transport vehicle is configured to run on an onboard battery, and a plurality of charging stations are provided on the track on which the transport vehicle can travel, and the vehicle is configured to be able to be charged by stopping at these charging stations, and the controller sets the charging station with the lowest utilization rate among the plurality of charging stations as the standby area, as described in claim 1.

4. The transport vehicle is configured to run on an onboard battery, and when the transport vehicle is put into standby mode, it is set to a low power consumption mode, according to any one of claims 1 to 3.

5. The above controller is a transport system according to any one of claims 1 to 3, which replaces the transport vehicles in standby mode at predetermined intervals, even if there is no change in the number of transport vehicles in standby mode.

6. The transport system according to any one of claims 1 to 3, wherein the transport vehicle is configured to run on an onboard battery, and the controller preferentially selects a transport vehicle with a high number of battery charging cycles and puts it into standby mode.

7. The transport system according to any one of claims 1 to 3, wherein the track on which the transport vehicle travels is formed in a grid pattern, and the transport vehicle is configured to be able to go straight, turn right, and turn left at each intersection of the grid-like track.

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