Overhead transport vehicle system and overhead transport vehicle

Abstract

Each of a plurality of transport vehicles (1) provided in an overhead transport vehicle system (80) comprises: a detection part (20) that is provided to a gripping part (6) and that detects that the gripping part (6) has reached a prescribed position with respect to an article (90) mounted on a station (102); a raising / lowering part (5) that raises and lowers the gripping part (6); a transport vehicle controller (7) that causes the gripping part (6) to lower at a first speed (V1) with respect to a body part (2) and then causes the gripping part (6) to lower from a teaching position (P1) stored in advance in a storage unit (70A) at a second speed (V2) which is slower than the first speed (V1), and causes the gripping part (6) to stop when the article (90) is detected by the detection part (20) so as to transfer the article (90) to the transport vehicle (1); and a teaching position correction part (7) that corrects the teaching position (P1) stored for each of a plurality of stations (102) on the basis of the stop position of the gripping part (6) during the transfer of the article (90).

Description

Overhead transport vehicle system and overhead transport vehicle

[0001] One aspect of the present invention relates to an overhead transport vehicle system and an overhead transport vehicle.

[0002] Overhead guided vehicles are known that travel along a track supported by a ceiling to transfer items to a station. The overhead guided vehicles include a gripper that grips an item and a lifting unit that raises and lowers the gripper. The gripper is lowered to transfer the item to the station. In such overhead guided vehicles, the gripper is lowered based on a pre-stored setting value to transfer the item to the station. However, if the relative distance between the overhead guided vehicle and the station, or the difference between the controlled distance and the actual lowering distance, changes due to various factors (e.g., a change in ceiling height due to snow accumulation, or a stretch in a belt or the like that suspends the gripper), the gripper may crush the item, or the item may not be able to be gripped properly.

[0003] As a technology for solving such problems, for example, Patent Document 1 discloses an overhead transport vehicle system equipped with a laser distance sensor that detects the distance between the overhead transport vehicle and a station. In the overhead transport vehicle system described in Patent Document 1, a set value is corrected based on the detection result of the laser distance sensor obtained when transferring an article, and the gripper is lowered based on the corrected set value.

[0004] Japanese Patent Application Laid-Open No. 2005-170554

[0005] Another possible method for solving the above problem without using a laser distance sensor is to lower the gripper at a predetermined speed to a pre-stored teaching position, and then lower the gripper at a slow speed so that it can stop immediately after passing the teaching position. However, in this case, the teaching position must be set unnecessarily high in order to properly transfer the article even if an unintended event such as the above occurs. With such an overhead transport vehicle, it takes time to transfer the article to the station.

[0006] Therefore, one aspect of the present invention aims to provide an overhead transport vehicle system and an overhead transport vehicle that can transfer items to a station appropriately and in a short time even when the distance between the teaching position and the stopping position changes due to various factors.

[0007] A ceiling transport vehicle system according to one aspect of the present invention is a ceiling transport vehicle system comprising a plurality of transport vehicles that transfer items to a plurality of stations by raising and lowering a gripping unit that grips the items relative to a main body unit that runs on a track supported on the ceiling, and each of the plurality of transport vehicles is provided with a detection unit in the gripping unit that detects the item, a lifting unit that raises and lowers the gripping unit, a transport vehicle controller that lowers the gripping unit relative to the main body unit at a first speed, and then lowers the gripping unit at a second speed slower than the first speed from a taught position pre-stored in a memory unit, and stops the gripping unit when the detection unit detects the item, thereby transferring the item to the transport vehicle, and a teaching position correction unit that corrects the teaching position stored for each of the plurality of stations based on the stopping position of the gripping unit when the item is transferred.

[0008] An overhead transport vehicle according to one aspect of the present invention is a ceiling transport vehicle that transfers items to a plurality of stations by raising and lowering a gripping unit that grips the items relative to a main body unit that runs on a track supported on the ceiling, and is equipped with a detection unit provided on the gripping unit that detects the item, a lifting unit that raises and lowers the gripping unit, a transport vehicle controller that lowers the gripping unit relative to the main body unit at a first speed, and then lowers the gripping unit at a second speed slower than the first speed from a taught position pre-stored in a memory unit, and stops the gripping unit when the detection unit detects the item, thereby transferring the item to the transport vehicle, and a taught position correction unit that corrects the taught position stored for each station based on the stopping position of the gripping unit when the item is transferred.

[0009] In the overhead transport vehicle system and overhead transport vehicle configured as described above, even if the positional relationship (distance) between the taught position and the stop position becomes too short or too long due to various factors, the taught position for each station is appropriately corrected based on the stop position when an item is transferred to the station. As a result, even if the distance between the taught position and the stop position unintentionally becomes wider or shorter, the correction can be used to return the distance to an appropriate value for the next transfer operation. As a result, even if the distance between the taught position and the stop position changes due to various factors, an item can be transferred to the station appropriately and in a short time.

[0010] In an overhead transport vehicle system according to one aspect of the present invention, the memory unit may store one teaching position associated with each of a plurality of stations, and the teaching position correction unit may correct the teaching position based on the stop positions acquired each time the plurality of transport vehicles perform all transfer operations. In this configuration, the correction value can be updated regardless of which transport vehicle transfers an item to the station. This allows the correction value to be updated frequently, making it possible to quickly respond to unintended factors.

[0011] In an overhead transport vehicle system according to one aspect of the present invention, the memory unit may store a teaching position corresponding to each of a plurality of transport vehicles for each of a plurality of stations, and the teaching position correction unit may correct the teaching position based on the stop position acquired by each of the transport vehicles for each of the plurality of stations. In this configuration, the positional relationship (distance) between the teaching position and the stop position is set between each station and each transport vehicle. This makes it possible to address problems caused by machine differences, such as elongation of the belt that suspends the gripper.

[0012] In the overhead transport vehicle system according to one aspect of the present invention, the storage unit may be provided in each of the multiple transport vehicles. In this configuration, the information required for correcting the teaching position (the distance between the teaching position and the stop position) for each transport vehicle is stored in the vehicle itself, thereby reducing the amount of communication required when correcting the teaching position.

[0013] According to one aspect of the present invention, an article can be transferred to a station appropriately and in a short time.

[0014] FIG. 1 is a side view of an overhead transport vehicle according to this embodiment. FIG. 2 is a side view of the overhead transport vehicle of FIG. 1 when the gripper is lowered. FIG. 3 is a front view showing the relationship between the teaching position and the stop position. FIG. 4 is a functional block diagram showing the functional configuration of the overhead transport vehicle of FIG. 1. FIG. 5 is a VT graph when the lifting unit is lowered. FIG. 6 is a flowchart showing the flow of teaching position correction by the overhead transport vehicle system of FIG. 1. FIG. 7 is a flowchart continuing from FIG. 6. FIG. 8(A) is an example of a data configuration stored in the teaching position memory unit of the area controller. FIG. 8(B) is an example of a data configuration stored in the teaching position memory unit of the first car in Modification 1. FIG. 8(C) is an example of a data configuration stored in the teaching position memory unit of the second car in Modification 1. FIG. 8(D) is an example of a data configuration stored in the teaching position memory unit of the area controller in Modification 2. FIG. 9 is a flowchart showing the flow of teaching position correction by the overhead transport vehicle system according to the modification. Fig. 10 is a flowchart showing the flow of correction of the teaching position, continuing from Fig. 9. Fig. 11 is a flowchart showing the flow of correction of the teaching position by an overhead transport vehicle system according to a further modified example.

[0015] Hereinafter, an overhead transport vehicle system 80 according to one embodiment will be described with reference to the drawings. In the description of the drawings, the same elements are given the same reference numerals, and duplicated explanations will be omitted.

[0016] As shown in Figures 1 and 2, the ceiling transport vehicle system 80 comprises a plurality of ceiling transport vehicles 1 (hereinafter simply referred to as "transport vehicles 1"), a plurality of load ports 102, and an area controller (teach position correction unit) 70 (see Figure 4).

[0017] The transport vehicle 1 travels along a traveling rail (track) 101 laid near the ceiling C of a clean room where semiconductor devices are manufactured. The transport vehicle 1 transports a FOUP (item) 90, which is a container that houses a plurality of semiconductor wafers. The transport vehicle 1 transfers the FOUP 90 to a load port (station) 102 provided in a processing device that performs various processes on the semiconductor wafers. In other words, the transport vehicle 1 retrieves the FOUP 90 placed on a placement surface 102a of the load port 102, and places the FOUP 90 on the placement surface 102a of the load port 102.

[0018] The transport vehicle 1 includes a traveling unit 2, a lateral feed unit 3, a rotating unit 4, a lifting unit 5, a gripping unit 6, and a transport vehicle controller (taught position correction unit) 7. The traveling unit 2 travels along the traveling rail 101 by receiving a contactless supply of power, for example, from a high-frequency current line laid along the traveling rail 101. The lateral feed unit 3 moves the rotating unit 4, the lifting unit 5, and the gripping unit 6 in a direction transverse to the direction in which the traveling rail 101 extends. The rotating unit 4 rotates the lifting unit 5 and the gripping unit 6 in a horizontal plane. The lifting unit 5 has multiple belts 5a, and the gripping unit 6 is attached to the lower end of the belts 5a.

[0019] The lifting unit 5 raises and lowers the gripping unit 6 by reeling out or reeling in a plurality of belts (hanging members) 5a. The gripping unit 6 grips a flange portion 91 of the FOUP 90 by closing a pair of claw members 6a. The gripping unit 6 releases the gripped state of the flange portion 91 by opening the pair of claw members 6a.

[0020] In Figure 1, the X, Y, and Z axes are shown together. The Y direction in the figure is the traveling direction of the ceiling transport vehicle 1, and the X direction in the figure is the lateral movement direction in which the gripping unit 6 and other parts are moved by the lateral feed unit 3. The Z direction in the figure is the vertical direction. The ceiling transport vehicle 1 lowers the gripping unit 6 along the Z direction and raises the gripping unit 6 along the Z direction. The traveling direction (Y direction) of the ceiling transport vehicle 1, the lateral movement direction (X direction) by the lateral feed unit 3, and the vertical direction (Z direction) are all perpendicular to one another. Note that the X, Y, and Z axes are also shown together in Figures 2 and 3, which will be referred to in the following description.

[0021] 1 and 2, the transport vehicle 1 further includes a center cone 8, a dog 10, and a flange detection unit (detection unit) 20. An upwardly open recess 91a is formed in the center of the flange 91 of the FOUP 90. The center cone 8 is fitted into the recess 91a of the flange 91 and is a member for positioning the gripper 6 relative to the FOUP 90. The center cone 8, the dog 10, and the flange detection unit 20 are provided on the gripper 6. The center cone 8, the dog 10, and the flange detection unit 20 are attached to a base (not shown) of the gripper 6. The center cone 8 is biased downward by a spring (not shown) attached to the base, and is movable up and down relative to the gripper 6.

[0022] 1, 2, and 4, the transport vehicle controller 7 is a part that controls the operation of each part of the transport vehicle 1, and is configured to include a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), etc. The transport vehicle controller 7 may be configured as hardware.

[0023] The transfer operation of the transport vehicle 1 will be described below. When gripping a FOUP 90 placed on the load port 102, the transport vehicle controller 7 controls the lowering of the gripper 6, and the center cone 8 fits into the recess 91a of the flange 91. As the gripper 6 further descends, the center cone 8 rises relative to the gripper 6. The transport vehicle controller 7 detects that the gripper 6 has reached the gripping position (stop position P2) (see FIGS. 2 and 3 ) using a photointerrupter consisting of a light-emitting unit and a light-receiving unit of the flange detection unit 20 and a light-shielding plate of the dog 10 that passes on the optical axis of the photointerrupter. In other words, the center cone 8, the dog 10, and the flange detection unit 20 can be said to be provided on the gripper 6 and to constitute a contact sensor that detects contact with the FOUP 90. When the transport vehicle controller 7 detects that the gripper 6 has reached the gripping position, it stops the lowering of the gripper 6.

[0024] The transport vehicle controller 7 causes the gripper 6 to close the pair of claw members 6a. Closing the claw members 6a causes the claw members 6a to enter the underside of the flange portion 91. The transport vehicle controller 7 then causes the lifting unit 5 to start raising the gripper 6. When the gripper 6 holding the FOUP 90 places the FOUP 90 on the placement surface 102a of the load port 102, that is, when unloading, the operation is the opposite of the operation when gripping the object.

[0025] The flange detection unit 20 detects that the gripper 6 has reached a predetermined position relative to the FOUP 90 placed on the load port 102. Recognition of the position of the gripper 6 and recognition of the gripping state of the FOUP 90 by the gripper 6 using the center cone 8, the dog 10, and the flange detection unit 20 are realized, for example, by the configuration and method described in Patent Document 1 (WO 2018 / 179931) mentioned above. However, recognition of the position of the gripper 6 and recognition of the gripping state of the FOUP 90 by the gripper 6 may also be achieved by other known configurations and methods.

[0026] The lifting unit 5 has a lifting motor (not shown), which lowers the gripping unit 6 by unwinding the belt 5a, and lifts the gripping unit 6 by winding up the belt 5a. The lifting motor is driven and controlled by the transport vehicle controller 7. The transport vehicle controller 7 can detect the amount of belt 5a being unwound (belt length) by receiving a signal related to rotation from the lifting motor. The transport vehicle controller 7 can position the gripping unit 6 at any position in the vertical direction based on the amount of belt 5a being unwound (belt length). In this embodiment, the transport vehicle controller 7 positions the gripping unit 6 at the taught position P1 based on the amount of belt 5a being unwound (belt length). The transport vehicle controller 7 can also obtain the position (height position) of the gripping unit 6 at the stop position P2 (the gripping position where the FOUP 90 is gripped) based on the amount of belt 5a being unwound.

[0027] 3 and 5 , when transferring a FOUP 90 to the load port 102, the transport vehicle controller 7 lowers the gripper 6 relative to the traveling unit (main body) 2 at a first speed V1, and then lowers the gripper 6 from a pre-stored taught position P1 at a second speed V2 slower than the first speed V1, and stops the gripper 6 when the flange detection unit 20 detects the FOUP 90. More specifically, the transport vehicle controller 7 controls the lifting unit 5 so that the gripper 6 descends at the first speed V1 from a traveling position P0, which is the position of the gripper 6 when the transport vehicle 1 is traveling.

[0028] Next, the transport vehicle controller 7 controls the lifting unit 5 so that the gripper 6 descends from the taught position P1 at a second speed V2. The second speed V2 is, for example, a speed at which the gripper 6 can be stopped in a relatively short distance (e.g., 5 mm) when the lifting unit 5 is controlled to stop. The transport vehicle controller 7 controls the lifting unit 5 to stop the descent of the gripper 6 when the flange detection unit 20 detects the FOUP 90 (i.e., when it detects that the gripper 6 has reached a predetermined position with respect to the FOUP 90 placed on the load port 102).

[0029] Under such control by the transport vehicle controller 7, when the transport vehicle 1 transfers a FOUP 90 to the load port 102, the transport vehicle 1 initially lowers the gripper 6 at a high speed, and then lowers the gripper 6 at a slower speed from the taught position close to the FOUP 90. This shortens the time required for descent to the taught position, and by subsequently allowing the gripper 6 to descend slowly, it is possible to reduce impact when placing the FOUP 90 on the load port 102 and to prevent the gripper 6 from colliding with the flange 91 of the FOUP 90 when gripping the FOUP 90 placed on the load port 102. Such a taught position is set so that the distance between the taught position and the stop position P2 falls within a predetermined range. The taught position is stored by the transport vehicle controller 7 as a taught position P1, and the initial value of the taught position P1 is set as appropriate, for example, when the ceiling transport vehicle system 80 is installed.

[0030] The transport vehicle controller 7 corrects the taught position P1 stored for each of the multiple load ports 102 based on the actual stop position P2 of the gripper 6 when transferring the FOUP 90. Specifically, the area controller 70 determines whether the distance difference between the taught position P1 and the stop position P2 falls within a predetermined range (e.g., within ±5 mm). If the area controller 70 determines that the distance difference does not fall within the predetermined range, it calculates a correction value for the taught position P1 based on the stop position P2. The correction value is, for example, a shift amount relative to the taught position P1, indicating how much the taught position P1 needs to be shifted from the taught position P1 so that the distance from the stop position P2 falls within the predetermined range. The transport vehicle controller 7 transmits the correction value for the taught position P1 calculated in this manner to the area controller 70. In addition, when the transport vehicle controller 7 can obtain a correction value for the teaching position P1 from the area controller 70 during transfer, it determines whether the distance difference between the teaching position P1 and the stop position P2 taking the correction value into account falls within a specified range, and if it determines that the distance difference does not fall within the specified range, it calculates a correction value for the teaching position P1 based on the stop position P2.

[0031] The area controller 70 is configured to include a CPU, a ROM, a RAM, etc. The area controller 70 can be configured as software in which a program stored in the ROM is loaded onto the RAM and executed by the CPU, for example. The area controller 70 may also be configured as hardware such as electronic circuits. The area controller 70 transmits, for example, a transport command to cause the transport vehicle 1 to transport the FOUP 90. The area controller 70 is configured to be able to communicate with the transport vehicle 1 via a power supply unit or the like arranged on the traveling rail 101.

[0032] The area controller 70 includes a teaching position storage unit 70A that stores information about the teaching position P1. The teaching position storage unit 70A is a storage device such as a hard disk drive (HDD) or a solid state drive (SSD). As shown in FIG. 8A , the teaching position storage unit 70A stores a correction value for one teaching position P1 associated with each of a plurality of load ports 102 provided in the ceiling transport vehicle system 80.

[0033] The area controller 70 stores the correction values ​​of the taught position P1 transmitted from the multiple transport vehicles 1 in the taught position memory unit 70A. If the correction value of the taught position P1 is not stored in the taught position memory unit 70A, the area controller 70 newly stores the transmitted correction value of the taught position P1. If the correction value of the taught position P1 is already stored, the area controller 70 overwrites (updates) it with the transmitted correction value of the taught position P1. It can be said that the area controller 70 of this embodiment corrects the taught position P1 based on the stop position P2 acquired every time a transfer operation is performed by the multiple transport vehicles 1. In other words, in this embodiment, the taught position P1 for one load port 102 can be corrected by each transfer operation of the multiple transport vehicles 1.

[0034] In the overhead transport vehicle system 80 described above, the correction of the taught position P1 executed by the area controller 70 will be described with reference to the flowcharts of Figures 6 and 7. Here, an example will be described in which the taught position P1 is corrected by two of the multiple transport vehicles 1, 1, and the correction value has already been stored in the taught position memory unit 70A of the area controller 70. For ease of explanation, the two transport vehicles 1, 1 will be referred to as the first transport vehicle 1A and the second transport vehicle 1B, respectively.

[0035] 6, when the first vehicle 1A transfers a FOUP 90 to load port A (hereinafter simply referred to as "port A"), which is one of the multiple load ports 102, the transport vehicle controller 7 of the first vehicle 1A inquires of the area controller 70 about a correction value for the taught position P1 of port A (hereinafter referred to as the "correction value of port A") (step S1). Upon receiving the inquiry, the area controller 70 extracts the correction value of port A from the taught position memory unit 70A (step S2) and transmits the correction value of port A to the transport vehicle controller 7 of the first vehicle 1A (step S3). The transport vehicle controller 7 of the first vehicle 1A receives the correction value of port A transmitted from the area controller 70 (step S4).

[0036] The transport vehicle controller 7 of the first vehicle 1A transfers the FOUP 90 to port A based on the pre-stored taught position P1 and the port A correction value (step S5). The transport vehicle controller 7 of the first vehicle 1A determines whether the difference between the stop position P2 at the time of transfer and the taught position P1 taking the correction value into account is within a predetermined range. If the transport vehicle controller 7 of the first vehicle 1A determines that the difference is not within the predetermined range, it calculates a correction value (port A correction value) for correcting the taught position P1 to fall within the predetermined range based on the stop position P2 (step S6). The transport vehicle controller 7 of the first vehicle 1A transmits the calculated port A correction value to the area controller 70 (step S7). The area controller 70 stores (updates) the port A correction value received from the first vehicle 1A in the taught position memory unit 70A (step S8). Specifically, the area controller 70 updates the database as shown in FIG. 8A.

[0037] When second car 1B transfers FOUP 90 to port A, transport vehicle controller 7 of second car 1B inquires of area controller 70 about the correction value of port A (step S11). Upon receiving the inquiry, area controller 70 extracts the correction value of port A from taught position memory unit 70A (step S12) and transmits the correction value of port A to transport vehicle controller 7 of second car 1B (step S13). Transport vehicle controller 7 of second car 1B receives the correction value of port A transmitted from area controller 70 (step S14).

[0038] The transport vehicle controller 7 of the second vehicle 1B transfers the FOUP 90 to port A based on the pre-stored taught position P1 and the port A correction value (step S15). The transport vehicle controller 7 of the second vehicle 1B determines whether the difference between the stop position P2 at the time of transfer and the taught position P1 taking the correction value into account is within a predetermined range. If the transport vehicle controller 7 of the second vehicle 1B determines that the difference is not within the predetermined range, it calculates a correction value (port A correction value) to correct the taught position P1 based on the stop position P2 so that it falls within the predetermined range (step S16). As shown in Figure 7, the transport vehicle controller 7 of the second vehicle 1B transmits the calculated port A correction value to the area controller 70 (step S17). The area controller 70 stores (updates) the port A correction value received from the second vehicle 1B in the taught position memory unit 70A (step S18). Specifically, the area controller 70 updates the database as shown in FIG. 8(A).

[0039] Note that transport vehicles 1 other than the first vehicle 1A and the second vehicle 1B can also calculate the correction value of port A in a similar manner and transmit it to the area controller 70. The area controller 70 can store (update) the correction value of port A received from transport vehicles 1 other than the first vehicle 1A and the second vehicle 1B in the teaching position memory unit 70A.

[0040] When the first vehicle 1A transfers a FOUP 90 to load port B (hereinafter simply referred to as "port B"), which is one of the multiple load ports 102, the transport vehicle controller 7 of the first vehicle 1A inquires of the area controller 70 about the correction value for port B (step S21). The area controller 70, having received the inquiry, extracts the correction value for port B from the taught position memory unit 70A (step S22) and transmits the correction value for port B to the transport vehicle controller 7 of the first vehicle 1A (step S23). The transport vehicle controller 7 of the first vehicle 1A receives the correction value for port B transmitted from the area controller 70 (step S24).

[0041] The transport vehicle controller 7 of the first vehicle 1A transfers the FOUP 90 to port B based on the pre-stored taught position P1 and the correction value for port B (step S25). The transport vehicle controller 7 of the first vehicle 1A determines whether the difference between the stop position P2 at the time of transfer and the taught position P1 taking the correction value into account is within a predetermined range. If the transport vehicle controller 7 of the first vehicle 1A determines that the difference is not within the predetermined range, it calculates a correction value (port B correction value) for correcting the taught position P1 to fall within the predetermined range based on the stop position P2 (step S26). The transport vehicle controller 7 of the first vehicle 1A transmits the calculated port B correction value to the area controller 70 (step S27). The area controller 70 stores (updates) the port B correction value received from the first vehicle 1A in the taught position memory unit 70A (step S28). Specifically, the area controller 70 updates the database as shown in FIG. 8(A).

[0042] Note that guided vehicles 1 other than the first vehicle 1A can also calculate the correction value of port B in a similar manner and transmit it to the area controller 70. The area controller 70 can store (update) the correction value of port B received from guided vehicles 1 other than the first vehicle 1A in the teaching position storage unit 70A. Specifically, the area controller 70 updates the database as shown in FIG. 8(A).

[0043] The effects of the overhead transport vehicle system 80 of the above embodiment will be described. In the overhead transport vehicle system 80 of the above embodiment, when the gripper 6 is lowered, it is lowered at high speed in sections where the possibility of collision is low and at low speed in sections where the possibility of collision is high. The starting point of this section where the possibility of collision is high is pre-stored as the taught position P1. However, due to factors such as those described above, the positional relationship (distance) between the taught position P1 and the stop position P2 may be unintentionally too short or too long. If this relationship is unintentionally too short, the FOUP 90 cannot be properly transferred to the load port 102. If this relationship is unintentionally too long, it takes time to transfer the FOUP 90 to the load port 102. In this regard, in the overhead transport vehicle system 80 of the above embodiment, the taught position P1 for each load port 102 is appropriately corrected based on the stop position P2 during transfer to the load port 102. As a result, even if the distance between the teaching position P1 and the stop position P2 unintentionally widens or shortens, the distance can be returned to an appropriate distance by this correction, so that the FOUP 90 can be transferred to the load port 102 appropriately and in a short time.

[0044] In the ceiling transport vehicle system 80 of the above embodiment, the taught position storage unit 70A stores one taught position P1 associated with each of the multiple load ports 102, and the area controller 70 corrects the taught position P1 based on the stop position P2 acquired each time a transfer operation is performed by the multiple transport vehicles 1. This makes it possible to update the correction value regardless of which transport vehicle 1 transfers a FOUP 90 to the load port 102. This makes it possible to update the correction value frequently, making it possible to respond quickly to unintended factors.

[0045] Although one embodiment has been described above, one aspect of the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the invention.

[0046] (Variant 1) In the above embodiment, the teaching position memory unit 70A associates and stores one teaching position P1 for each of multiple load ports 102, and the area controller 70 corrects the teaching position P1 based on the stop position P2 obtained each time a transfer operation is performed by multiple transport vehicles 1, but this is not limited to this example.

[0047] In the guided vehicle 1 according to the first modification, the teaching position storage unit 7A may be provided in the guided vehicle controller 7 instead of the area controller 70. The teaching position storage unit 70A is a storage device such as a hard disk drive (HDD) or a solid state drive (SSD). The teaching position storage unit 7A is a storage device such as a hard disk drive (HDD) or a solid state drive (SSD). The teaching position storage unit 7A is provided for each guided vehicle 1, and as shown in FIGS. 8B and 8C, stores teaching positions P1 corresponding to each of the multiple guided vehicles 1 for each of the multiple load ports 102. The guided vehicle controller 7 then corrects the teaching positions P1 based on the stop positions P2 acquired by each of the guided vehicles 1 for each of the multiple load ports 102.

[0048] The correction of the taught position P1 executed by the carrier controller 7 in the carrier 1 according to the first modification will be described with reference to the flowchart in Figure 9. Here, an example will be described in which two carriers 1, 1 among the multiple carriers 1 correct the taught position P1 using their own carrier controller 7, and the correction value has already been stored in the taught position memory unit 7A of the carrier controller 7 of each carrier 1. Again, for ease of explanation, the two carriers 1, 1 will be referred to as the first carrier 1A and the second carrier 1B, respectively.

[0049] The first vehicle 1A transfers the FOUP 90 to port A. The transport vehicle controller 7 of the first vehicle 1A transfers the FOUP 90 to port A based on the pre-stored taught position P1 and the correction value for port A (step S41). The transport vehicle controller 7 of the first vehicle 1A determines whether the difference between the stop position P2 at the time of transfer and the taught position P1 taking the correction value into account is within a predetermined range. If the transport vehicle controller 7 of the first vehicle 1A determines that the difference is not within the predetermined range, it calculates a correction value (port A correction value) for correcting the taught position P1 to fall within the predetermined range based on the stop position P2 (step S42). The transport vehicle controller 7 of the first vehicle 1A stores (updates) the calculated port A correction value in the taught position memory unit 7A (step S43). Specifically, the transport vehicle controller 7 updates the database as shown in FIG. 8(B).

[0050] Next, the first vehicle 1A transfers the FOUP 90 to port B. The transport vehicle controller 7 of the first vehicle 1A transfers the FOUP 90 to port B based on the pre-stored taught position P1 and the correction value for port B (step S44). The transport vehicle controller 7 of the first vehicle 1A determines whether the difference between the stop position P2 at the time of transfer and the taught position P1 taking the correction value into account is within a predetermined range. If the transport vehicle controller 7 of the first vehicle 1A determines that the difference is not within the predetermined range, it calculates a correction value (port B correction value) for correcting the taught position P1 to fall within the predetermined range based on the stop position P2 (step S45). The transport vehicle controller 7 of the first vehicle 1A stores (updates) the calculated correction value for port B in the taught position memory unit 7A (step S46). Specifically, the transport vehicle controller 7 updates the database as shown in FIG. 8B.

[0051] Similarly to the first car 1A, the second car 1B also executes steps S51 to S53 shown in Figure 9 to store (update) the correction value for port A in the teaching position memory unit 7A provided in its own transport vehicle controller 7. The second car 1B also executes steps S54 to S56 shown in Figure 9 to store (update) the correction value for port B in the teaching position memory unit 7A. In these cases, the transport vehicle controller 7 updates the database as shown in Figure 8(C).

[0052] In the transport vehicle 1 according to the first modification, the positional relationship (distance) between the teaching position P1 and the stopping position P2 is set between each load port 102 and each transport vehicle 1. This makes it possible to deal with problems caused by machine differences, such as elongation of the belt 5a that suspends the gripper 6. Furthermore, in the transport vehicle 1 according to the first modification, the teaching position P1 is corrected for each transport vehicle 1, so the amount of communication required when correcting the teaching position P1 can be reduced.

[0053] (Variation 2) In the transport vehicle 1 according to Variation 1, an example has been described in which the transport vehicle controller 7 provided in each transport vehicle 1 corrects the taught position P1 and stores the corrected value in the taught position memory unit 7A provided in the transport vehicle controller 7 of each transport vehicle 1, but this is not limiting. In the ceiling transport vehicle system 80 according to Variation 2, the transport vehicle controller 7 of each transport vehicle 1 calculates a correction value for each port based on the stop position P2 acquired during transfer and transmits it to the area controller 70, and the area controller 70 stores (updates) the correction value for each port acquired from the transport vehicle controller 7 in the taught position memory unit 70A for each transport vehicle.

[0054] The correction of the taught position P1 executed by the area controller 70 in the overhead transport vehicle system 80 according to the second modification will be described with reference to the flowcharts in Figures 10 and 11. Here, the case where the taught position P1 is corrected by two of the multiple transport vehicles 1, 1, and the correction value has already been stored in the taught position memory unit 7A of the transport vehicle controller 7 of each transport vehicle 1 will be described as an example. For ease of explanation, the two transport vehicles 1, 1 will be referred to as the first transport vehicle 1A and the second transport vehicle 1B, respectively.

[0055] 10, when first car 1A transfers FOUP 90 to port A, transport vehicle controller 7 of first car 1A inquires of area controller 70 about the correction value of port A (step S61). Upon receiving the inquiry, area controller 70 extracts the correction value of port A of first car 1A from teaching position memory unit 70A (step S62) and transmits the correction value of port A of first car 1A to transport vehicle controller 7 of first car 1A (step S63). Transport vehicle controller 7 of first car 1A receives the correction value of port A of first car 1A transmitted from area controller 70 (step S64).

[0056] The transport vehicle controller 7 of the first vehicle 1A transfers the FOUP 90 to port A based on the pre-stored taught position P1 and the port A correction value (step S65). The transport vehicle controller 7 of the first vehicle 1A determines whether the difference between the stop position P2 at the time of transfer and the taught position P1 taking the correction value into account is within a predetermined range. If the transport vehicle controller 7 of the first vehicle 1A determines that the difference is not within the predetermined range, it calculates a correction value (port A correction value) for correcting the taught position P1 to fall within the predetermined range based on the stop position P2 (step S66). The transport vehicle controller 7 of the first vehicle 1A transmits the calculated port A correction value to the area controller 70 (step S67). The area controller 70 stores (updates) the port A correction value received from the first vehicle 1A in the taught position memory unit 70A as the port A correction value of the first vehicle 1A (step S68). Specifically, the area controller 70 updates the database as shown in FIG. 8(D).

[0057] When second car 1B transfers FOUP 90 to port A, transport vehicle controller 7 of second car 1B inquires of area controller 70 about the correction value of port A (step S71). Upon receiving the inquiry, area controller 70 extracts the correction value of port A of second car 1B from teaching position memory unit 70A (step S72) and transmits the correction value of port A of second car 1B to transport vehicle controller 7 of second car 1B (step S73). Transport vehicle controller 7 of second car 1B receives the correction value of port A of second car 1B transmitted from area controller 70 (step S74).

[0058] The transport vehicle controller 7 of the second car 1B transfers the FOUP 90 to port A based on the pre-stored taught position P1 and the correction value for port A (step S75). The transport vehicle controller 7 of the second car 1B determines whether the difference between the stop position P2 at the time of transfer and the taught position P1 taking the correction value into account is within a predetermined range. If the transport vehicle controller 7 of the second car 1B determines that the difference is not within the predetermined range, it calculates a correction value (port A correction value) for correcting the taught position P1 to fall within the predetermined range based on the stop position P2 (step S76). As shown in Figure 11, the transport vehicle controller 7 of the second car 1B transmits the calculated correction value for port A to the area controller 70 (step S77). The area controller 70 stores (updates) the correction value of port A received from the second car 1B in the teaching position storage unit 70A as the correction value of port A of the second car 1B (step S78). Specifically, the area controller 70 updates the database as shown in FIG. 8(D).

[0059] Note that transport vehicles 1 other than the first vehicle 1A and the second vehicle 1B can also calculate the correction value of port A in a similar manner and transmit it to the area controller 70. The area controller 70 can store (update) the correction value of port A received from transport vehicles 1 other than the first vehicle 1A and the second vehicle 1B as the correction value of port A of each transport vehicle 1 in the teaching position memory unit 70A.

[0060] When first car 1A transfers FOUP 90 to port B, transport vehicle controller 7 of first car 1A inquires of area controller 70 about the correction value of port B (step S81). Upon receiving the inquiry, area controller 70 extracts the correction value of port B of first car 1A from taught position memory unit 70A (step S82) and transmits the correction value of port B of first car 1A to transport vehicle controller 7 of first car 1A (step S83). Transport vehicle controller 7 of first car 1A receives the correction value of port B of first car 1A transmitted from area controller 70 (step S84).

[0061] The transport vehicle controller 7 of the first vehicle 1A transfers the FOUP 90 to port B based on the pre-stored taught position P1 and the port B correction value (step S85). The transport vehicle controller 7 of the first vehicle 1A determines whether the difference between the stop position P2 at the time of transfer and the taught position P1 taking the correction value into account is within a predetermined range. If the transport vehicle controller 7 of the first vehicle 1A determines that the difference is not within the predetermined range, it calculates a correction value (port B correction value) for correcting the taught position P1 to fall within the predetermined range based on the stop position P2 (step S86). The transport vehicle controller 7 of the first vehicle 1A transmits the calculated port B correction value to the area controller 70 (step S87). The area controller 70 stores (updates) the port B correction value received from the first vehicle 1A in the taught position memory unit 70A as the port B correction value of the first vehicle 1A (step S88). Specifically, the area controller 70 updates the database as shown in FIG. 8(D).

[0062] Note that guided vehicles 1 other than the first vehicle 1A can also calculate the correction value of port B in a similar manner and transmit it to the area controller 70. The area controller 70 can store (update) the correction value of port B received from guided vehicles 1 other than the first vehicle 1A in the taught position storage unit 70A as the correction value of port B of each guided vehicle 1. Specifically, the area controller 70 updates the database as shown in FIG. 8(D).

[0063] In the transport vehicle 1 according to the second modification, the positional relationship (distance) between the teaching position P1 and the stop position P2 is set between each load port 102 and each transport vehicle 1. This makes it possible to deal with problems caused by machine differences, such as elongation of the belt 5a that suspends the gripper 6.

[0064] (Other Modifications) In the above embodiment and Modification 2, an example has been described in which the transport vehicle controller 7 calculates the correction values ​​for port A and port B. However, the transport vehicle controller 7 may transmit only information related to the stop position P2, and the area controller 70 may calculate the correction values ​​for port A and port B. The method for calculating the correction values ​​for port A and port B is as described above.

[0065] In the above embodiment and the modified example, the correction value calculated during transfer is directly stored (updated) in the teaching position storage unit 7A (70A). However, this is not limiting. For example, when the area controller 70 (transport vehicle controller 7) determines that the distance difference between the teaching position P1 and the stop position P2 (the distance difference between the teaching position P1 and the stop position P2 taking the correction value into account) is not within a predetermined range (i.e., when it determines that a correction value needs to be calculated), the area controller 70 may use a predetermined small shift amount (e.g., 1 mm) as the correction value instead of the calculated correction value. Note that the shift amount is set to a value smaller than the correction value that would be calculated. Control according to this modified example prevents a single transfer operation from significantly changing the teaching position P1, i.e., from significantly varying the amount of movement when the gripper 6 descends at high speed.

[0066] In the above embodiment and the above modified example, an example was described in which the correction value is stored (updated) in the teaching position memory unit 7A (70A) each time the correction value is calculated for one transfer. However, this is not limited to this. For example, the area controller 70 (transport vehicle controller 7) may calculate a correction value and store (update) it in the teaching position memory unit 7A (70A) when the number of such determinations exceeds a predetermined number, rather than immediately calculating a correction value when it determines that the distance difference between the teaching position P1 and the stop position P2 (the distance difference between the teaching position P1 and the stop position P2 taking the correction value into account) is not within a predetermined range. In this modified example, the correction value can be updated after confirming that the distance difference is steadily changing.

[0067] In the above embodiment and modified example, an example has been described in which a transfer is performed to retrieve a FOUP 90 placed on the load port 102, but the stop position P2 can also be obtained when a transfer is performed to place a FOUP 90 on the load port 102. In other words, the above-mentioned correction value can be calculated.

[0068] 1...Ceiling transport vehicle (transport vehicle), 1A...First vehicle (transport vehicle), 1B...Second vehicle (transport vehicle), 2...Running unit (main body), 3...Lateral feed unit, 4...Rotating unit, 5...Lifting unit, 6...Gripping unit, 7...Transport vehicle controller (taught position correction unit), 7A...Taught position memory unit (memory unit), 20...Flange detection unit (detection unit), 70...Area controller (taught position correction unit), 70A...Taught position memory unit (memory unit), 80...Ceiling transport vehicle system, 101...Running rail, 102...Load port (station), P1...Taught position, P2...Stop position (gripping position).

Claims

1. A ceiling transport vehicle system includes a plurality of transport vehicles that raise and lower a gripping unit that grips an article relative to a main body unit that travels on a track supported on a ceiling by unwinding or winding a belt connected to the gripping unit, and transfers the article to a plurality of stations, Each of the plurality of transport vehicles a lifting unit that unwinds or winds the belt; a detection unit provided in the gripping unit, the detection unit detecting contact with the article placed on the station, thereby detecting that the gripping unit has reached a stop position where the gripping unit grips the article placed on the station; a memory unit that stores in advance, as the amount of belt payout, a teaching position that is set so that the distance from the stopping position falls within a predetermined range; a transport vehicle controller that controls the amount of lift of the gripper relative to the main body based on the amount of payout of the belt, lowers the gripper relative to the main body at a first speed, and then lowers the gripper from the taught position at a second speed slower than the first speed, and stops the gripper when the detection unit detects that the gripper has reached the stop position, thereby transferring the article to the transport vehicle, and acquires the amount of payout of the belt at the stop position; An overhead transport vehicle system comprising: a teaching position correction unit that corrects the amount of extension of the teaching position belt stored for each of the plurality of stations based on the actual stopping position of the gripping unit when the item is transferred.

2. the storage unit stores one of the teaching positions in association with each of the plurality of stations, The overhead transport vehicle system according to claim 1 , wherein the teaching position correcting unit corrects the teaching position based on the stop position acquired every time the plurality of transport vehicles perform all transfer operations.

3. the storage unit stores the teaching positions corresponding to the plurality of transport vehicles in association with each other for each of the plurality of stations, 3. The overhead transport vehicle system according to claim 1, wherein the teaching position correcting unit corrects the teaching position based on the stop position acquired by each of the transport vehicles for each of the plurality of stations.

4. 4. The overhead transport vehicle system according to claim 3, wherein the storage unit is provided in each of the plurality of transport vehicles.

5. A ceiling transport vehicle that lifts and lowers a gripping unit that grips an article relative to a main body that travels on a track supported on a ceiling by unwinding or winding a belt connected to the gripping unit, and transfers the article to a plurality of stations, a lifting unit that unwinds or winds the belt; a detection unit provided in the gripping unit, the detection unit detecting contact with the article placed on the station, thereby detecting that the gripping unit has reached a stop position where the gripping unit grips the article placed on the station; a memory unit that stores in advance, as the amount of belt payout, a teaching position that is set so that the distance from the stopping position falls within a predetermined range; a transport vehicle controller that controls the amount of lift of the gripper relative to the main body based on the amount of payout of the belt, lowers the gripper relative to the main body at a first speed, and then lowers the gripper from the taught position at a second speed slower than the first speed, and stops the gripper when the detection unit detects that the gripper has reached the stop position, thereby transferring the article to the station and acquiring the amount of payout of the belt at the stop position; and a teaching position correction unit that corrects the teaching position stored for each station based on the actual stopping position of the gripping unit when the article is transferred.