Transport vehicle

Abstract

To provide a transport vehicle capable of performing transfer of an article at a proper position even in the case where the weights of articles are different, in the case of performing unloading operation.SOLUTION: A transport vehicle (1) which holds an article (C) and travels on a track R includes: a holding part 21 for holding the article (C); a lifting device 7 for moving up / down the holding part 21 which has moved to a transfer position; a horizontal discharge mechanism 8 for moving the holding part 21 to the transfer position by sliding to the lateral side of the track R; an acquisition part for acquiring the weight of the article (C) held by the holding part 21; and a control part 130 for controlling the slide amount of the horizontal discharge mechanism 8. The control part 130 changes the slide amount according to the weight of the article (C) acquired by the acquisition part.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a transport vehicle. [Background technology]

[0002] Patent Document 1 discloses a transport vehicle that transports and transfers articles. This transport vehicle includes a gripping unit that grips the article, a memory unit that stores information about the transfer position of the article, and a lateral delivery mechanism to which the gripping unit is attached. The transport vehicle moves the lateral delivery mechanism a predetermined amount in a lateral direction perpendicular to the traveling direction to move the article laterally to the transfer position, and transfers the article to a loading unit such as a port.

[0003] The transfer of items by the transport vehicle involves an unloading operation in which the item is placed on the loading platform, and an item grabbing operation in which the item on the loading platform is held. The lateral delivery mechanism moves laterally without gripping an item during the item grabbing operation, but moves laterally while gripping an item during the unloading operation.

[0004] During unloading, the weight of the article may cause the lateral delivery mechanism to bend. If the lateral delivery mechanism bends during unloading, the position of the article may deviate from the transfer position after the lateral delivery mechanism moves a predetermined amount laterally. Therefore, in Patent Document 1, the amount of movement of the lateral delivery mechanism is made different between unloading and article grasping operations, so that the position of the article does not deviate during unloading. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 5636849 Summary of the Invention [Problem to be solved by the invention]

[0006] The weight of all the items transported by the transport vehicle is not always the same, and it is possible that items of various weights will be transported and placed on the loading section. However, the above transport vehicle does not mention or suggest the possibility of misalignment of the items that may occur when moving items of different weights laterally.

[0007] An object of the present invention is to provide a transport vehicle that can transfer and load articles at appropriate positions when unloading, even if the weights of the articles vary. [Means for solving the problem]

[0008] A ceiling transport vehicle according to one aspect of the present invention is a transport vehicle that holds items and travels on a track to transport them, and is equipped with a holding section that holds the items, a lifting device that raises and lowers the holding section that has moved to a transfer position, a side-discharge mechanism that moves the holding section to the transfer position by sliding to the side of the track, an acquisition section that acquires the weight of the items held by the holding section, and a control section that controls the amount of sliding of the side-discharge mechanism, and the control section changes the amount of sliding depending on the weight of the items acquired by the acquisition section. [Effects of the Invention]

[0009] The overhead transport vehicle according to the present invention changes the amount of sliding depending on the weight of the article being carried. With this configuration, even if the weight of the article varies, the article can be transferred to the appropriate position.

[0010] Furthermore, the overhead transport vehicle according to the above aspect may include a memory unit that stores a first slide amount, which is a slide amount corresponding to the position of the placement unit to which the article is transferred, and the control unit may slide the lateral delivery mechanism by a second slide amount obtained by correcting the first slide amount according to the weight of the article acquired by the acquisition unit. With this configuration, the overhead transport vehicle corrects the slide amount according to the weight of the article, so that the article can be transferred at an appropriate position.

[0011] In addition, according to the ceiling transport vehicle of the above aspect, it is provided with a lifting motor for raising and lowering the holding unit, and the acquisition unit may acquire the weight of the item held by the holding unit by measuring the weight of the item based on the torque of the lifting motor.

[0012] Furthermore, in the ceiling-mounted transport vehicle according to the above aspect, the acquisition unit may measure the weight of an item while the transport vehicle is holding an item in the holding unit and while the transport vehicle is stopped. For example, the transport vehicle may use an elevator motor to raise the holding unit holding the item to place the item in a predetermined space, and transport the item by traveling with the item stored in the predetermined space, and the acquisition unit may measure the weight of the item while the item is stored in the predetermined space and the transport vehicle is stopped. This configuration can improve the accuracy of measuring the weight of the item. Furthermore, in the ceiling-mounted transport vehicle according to the above aspect, the acquisition unit may acquire data on the weight of the item held in the holding unit from an external controller via wired or wireless communication, or may include a sensor that measures the weight of the item held by the holding unit.

[0013] Furthermore, in the overhead transport vehicle according to the above aspect, the storage unit may store correction information indicating a relationship between the weight of the article and a correction value for the slide amount, and the control unit may acquire a correction value corresponding to the weight of the article acquired by the acquisition unit from the correction information and correct the first slide amount based on the acquired correction value. Furthermore, the control unit may correct the first slide amount based on a first correction value that is a constant independent of the weight of the article and a second correction value corresponding to the weight of the article acquired by the acquisition unit. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a conceptual diagram showing an overhead transport vehicle according to a first embodiment. FIG. [Figure 2] 2 is a diagram showing a schematic electrical configuration of the ceiling transport vehicle according to the first embodiment. FIG. [Figure 3] 3A to 3C are diagrams illustrating a loading / unloading operation of the ceiling transport vehicle according to the first embodiment. [Figure 4]10A and 10B are diagrams illustrating the lateral dispensing operation when the weight of the container is small. [Figure 5] 10A and 10B are diagrams illustrating the lateral dispensing operation when the weight of the container is large. [Figure 6] 5 is a diagram schematically showing an example of the relationship between the mass of a container and the amount of displacement according to the first embodiment. FIG. [Figure 7] FIG. 2 is a diagram illustrating functional parts of a control unit according to the first embodiment. [Figure 8] 10 is a flowchart of a method for correcting a slide set amount in the ceiling transport vehicle 1 according to the first embodiment. [Figure 9] FIG. 10 is a diagram showing a schematic electrical configuration of an overhead transport vehicle according to a second embodiment. [Figure 10] FIG. 10 is a diagram showing a schematic electrical configuration of an overhead transport vehicle according to a third embodiment. [Figure 11] 10A and 10B are diagrams illustrating a method for correcting a slide set amount according to the third embodiment. [Figure 12] 10A and 10B are diagrams illustrating a modified example of a method for correcting a slide set amount according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention will be described below through embodiments, but the following embodiments are not limited to the inventions according to the claims. Furthermore, not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. In the drawings, identical or similar parts may be designated by the same reference numerals, and redundant explanations may be omitted. Furthermore, the shapes and sizes of elements in the drawings may be exaggerated for clarity, and may differ in shape and size from the actual product.

[0016] In the drawings, directions in the drawings may be explained using an XYZ coordinate system. In the XYZ coordinate system, a plane parallel to the horizontal plane is the XY plane. One direction in this XY plane is referred to as the X direction, and the direction perpendicular to the X direction is referred to as the Y direction. Furthermore, the direction perpendicular to the XY plane is referred to as the Z direction. The X, Y, and Z directions will be explained assuming that the direction indicated by the arrow in the drawing is the + direction, and the direction opposite to the arrow is the - direction.

[0017] FIG. 1 is a conceptual diagram of an overhead transport vehicle according to this embodiment. FIG. 1 conceptually shows an overhead transport vehicle 1 according to this embodiment as viewed from the -Y direction side. The overhead transport vehicle 1 is an example of a transport vehicle. The transport vehicle of the present invention is not limited to an overhead transport vehicle as long as it can transport articles. FIG. 2 is a diagram showing the schematic electrical configuration of the overhead transport vehicle according to this embodiment.

[0018] The ceiling transport vehicle 1 travels along a ceiling track R that is set higher than the floor, such as the ceiling of a clean room, and transports a container C suspended within the storage space AS. The ceiling transport vehicle 1 is used to transport the container C, for example, between a processing device and a container storage device, or between two processing devices. The X direction in FIG. 1 is the traveling direction of the ceiling transport vehicle 1. The Z direction in FIG. 1 is the vertical direction of the ceiling transport vehicle 1.

[0019] The overhead transport vehicle 1 is used to transport containers C, for example, between a processing device and a container storage device, or between two processing devices. The processing device is, for example, a film forming device, a coater / developer, an exposure device, an etching device, etc., and performs various processes in the process of manufacturing devices (e.g., semiconductor devices). The container storage device is, for example, disposed on a transport path for transporting the containers C and temporarily stores the containers C. The container storage device is, for example, disposed near the ceiling. The containers C store, for example, wafers or reticles used in the manufacture of semiconductor devices. The containers C are, for example, FOUPs (Front Opening Unified Pods), SMIF pods, or reticle pods whose interiors can be purged. The containers C are an example of an "article" in the present invention.

[0020] The ceiling transport vehicle 1 includes, for example, a traveling section 2, a connecting section 3a, a support section 3b, a main body section 4, a cover 5a, a cover 5b, a lifting section 6, and a control device 100.

[0021] The traveling unit 2 includes wheels 2a and a traveling drive unit 2b. The wheels 2a are arranged in contact with the overhead track R and are driven to rotate by the driving force of the traveling drive unit 2b. The traveling drive unit 2b generates the driving force for traveling the overhead transport vehicle 1. The traveling drive unit 2b has a traveling motor such as a linear motor or a rotary motor. The traveling drive unit 2b also has a rotary encoder or a linear encoder. The traveling drive unit 2b controls the linear motor or the rotary motor based on the detection results such as the number of rotations of the wheels 2a detected by the rotary encoder or the linear encoder, and increases or stops the speed of the overhead transport vehicle 1.

[0022] The connecting portion 3a connects the traveling drive unit 2b and the support unit 3b. For example, one end of the connecting portion 3a is connected to the traveling drive unit 2b, and the other end is connected to the support unit 3b. The support unit 3b is disposed along a horizontal plane and supports the main body unit 4.

[0023] The main body 4 is connected to the travel drive unit 2b via the connecting unit 3a, and moves along the ceiling track together with the travel unit 2. The main body 4 includes, for example, a lifting device 7 and a lateral feed mechanism 8. The lifting device 7 includes a lifting drive unit 11, a hanging member 12, and a torque sensor 40.

[0024] The lifting device 7 lowers or raises the lifting unit 6 at a predetermined speed, and maintains the lifting unit 6 at a target height. The lifting unit 6 is suspended from the main body 4 by a plurality of suspension members 12. The lifting drive unit 11 is, for example, a hoist, and lowers the lifting unit 6 by reeling out the plurality of suspension members 12. The lifting drive unit 11 also raises the lifting unit 6 by winding up the plurality of suspension members 12.

[0025] For example, the lifting drive unit 11 includes one or more rotating bodies 30 and a lifting motor 31. The rotating body 30 is, for example, a cylindrical drum having a winding surface for the hanging members 12 on its outer periphery. The lifting motor 31 is an electric motor that rotates the rotating body 30 to wind and unwind (lower) the multiple hanging members 12. Note that the lifting drive unit 11 may include, for example, rollers such as pulleys that support the multiple hanging members 12.

[0026] One end of the hanging member 12 is connected to the lifting drive unit 11, and the other end is connected to the lifting unit 6. The hanging member 12 is, for example, a belt. In this embodiment, the lifting unit 6 is hung from the main body unit 4 by, for example, three or four hanging members 12. However, the number of hanging members 12 is not particularly limited, and may be any number as long as there is more than one.

[0027] The torque sensor 40 measures the torque of the lift motor 31. The torque sensor 40 is connected to the control device 100. The torque sensor 40 outputs the measured torque of the lift motor 31 to the control device 100.

[0028] A cover 5a is provided on the -X side of the main body 4, and a cover 5b is provided on the +X side. The covers 5a and 5b are each fixed to the support 3b and extend from the support 3b in the -Z direction. The pair of covers 5a and 5b form a space in which the container C is accommodated, i.e., an accommodation space AS.

[0029] The lifting unit 6 includes a lifting platform 20 and a holding unit 21. The other ends of the multiple hanging members 12 are fixed to the lifting platform 20. The lifting platform 20 is, for example, a plate-like member, and is suspended by the multiple hanging members 12 so that its plane is parallel to the horizontal plane. However, in this embodiment, the shape of the lifting platform 20 is not particularly limited.

[0030] The holding unit 21 is fixed to the underside of the lifting platform 20. The holding unit 21 holds the container C. For example, the holding unit 21 holds the container C by gripping a flange of the container C, thereby suspending and holding the container C. The method by which the holding unit 21 grips the container C is not particularly limited, and the container C may be gripped from above, or may be gripped by pinching it from the left and right.

[0031] The holding unit 21 is, for example, a chuck having a plurality of claws 21a that are movable in the horizontal direction. The holding unit 21 moves the claws 21a below the flange by a driving force such as a motor. The lifting drive unit 11 then lifts the hanging member 12, causing the holding unit 21 to rise, thereby holding the container C in a suspended state.

[0032] The lateral delivery mechanism 8 moves the holding unit 21 in a direction to the side of the ceiling track R (hereinafter referred to as the "lateral direction"). In other words, the lateral delivery mechanism 8 supports the holding unit 21 in a cantilevered manner and protrudes it laterally. This allows the holding unit 21 to move laterally to a predetermined transfer position. In FIGS. 1 and 2, the traveling direction is the X direction, and the lateral direction is the Y direction. The lifting device 7 raises and lowers the holding unit 21 that has moved to the transfer position. For example, when the ceiling transport vehicle 1 unloads an item, the lifting device 7 lowers the holding unit 21 holding a container C from the transfer position and places the container C on the loading platform LD. On the other hand, when the ceiling transport vehicle 1 grips an item, the lifting device 7 lowers the holding unit 21 that has moved to the transfer position and lifts the holding unit 21 once it has gripped the container C on the loading platform LD.

[0033] The lateral ejection mechanism 8 includes, for example, a base portion 13 and one or more slide portions 14. The lateral ejection mechanism 8 illustrated in FIG. 1 has two slide portions 14. One slide portion 14 may be referred to as a "first slide portion 14A," and the other slide portion 14 may be referred to as a "second slide portion 14B."

[0034] The base portion 13 is attached below the connecting portion 3a. The base portion 13 is attached to, for example, the support portion 3b. The base portion 13 is, for example, a plate-shaped member. The base portion 13 is arranged so that the plane of the base portion 13 is parallel to the horizontal direction.

[0035] The first sliding portion 14A is disposed on the underside of the base portion 13. The first sliding portion 14A is, for example, a plate-shaped member, and is disposed so that its plane is parallel to the plane of the base portion 13 in the Z direction. The first sliding portion 14A has, for example, the same shape as the base portion 13. The first sliding portion 14A is slidable in the lateral direction relative to the base portion 13.

[0036] The second slide portion 14B is disposed on the underside of the first slide portion 14A. The second slide portion 14B is, for example, a plate-shaped member, and is disposed so that its plane in the Z direction is parallel to the plane of the base portion 13 and the plane of the first slide portion 14A. The second slide portion 14B has, for example, the same shape as the first slide portion 14A. The lifting drive unit 11 is provided on the underside of the second slide portion 14B.

[0037] The second slide portion 14B is slidable laterally relative to the first slide portion 14A. The lateral extension mechanism 8 has, for example, a drive unit 15, and uses the driving force from the drive unit 15 to slide the first slide portion 14A laterally relative to the base portion 13, and also slides the second slide portion 14B in the same laterally direction relative to the first slide portion 14A in conjunction with the sliding movement of the first slide portion 14A. Note that the lateral extension mechanism 8 only needs to have a configuration that can laterally extend the lift drive unit 11, and may employ a configuration including a base portion 13 and one slide portion 14, or may employ a configuration including a base portion 13 and three or more slide portions 14.

[0038] The driving device 15 is provided, for example, on the base unit 13. The driving device 15 includes, for example, a transfer motor 16 and a rotation amount detection unit 17.

[0039] The transfer motor 16 is a drive source for sliding the lateral feeding mechanism 8 laterally. That is, by driving the transfer motor 16, the first slide portion 14A slides laterally relative to the base portion 13, and the second slide portion 14B slides laterally relative to the first slide portion 14A. Note that, hereinafter, the operation of sliding the multiple slide portions 14 to slide the holding portion 21 laterally may be referred to as the "lateral feeding operation."

[0040] The rotation amount detection unit 17 detects the amount of rotation of the transfer motor 16. The rotation amount detection unit 17 is connected to the control device 100. The rotation amount detection unit 17 is, for example, an encoder. The rotation amount detection unit 17 outputs, for example, a signal corresponding to the amount of rotation of the transfer motor 16 (hereinafter referred to as a "rotation signal") to the control device 100.

[0041] The rotation signal is, for example, a pulse signal corresponding to the rotation amount of the transfer motor 16. The control device 100 can recognize the current slide amount of the lateral delivery mechanism 8 by using the pulse signal corresponding to the rotation amount of the transfer motor 16. The slide amount of the lateral delivery mechanism 8 is the distance by which the slide part 14 is slid during the lateral delivery operation. In other words, the slide amount of the lateral delivery mechanism 8 is the length by which the slide part 14 is advanced by the driving force of the transfer motor 16 during the lateral delivery operation.

[0042] The control device 100 may include a processor such as a CPU (Central Processing Unit) or an MPU (Micro Processing Unit) and non-volatile or volatile semiconductor memory (e.g., RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable Read Only Memory), and EEPROM (Electrically Erasable Programmable Read Only Memory)). For example, the control device 100 may be a microcontroller such as an MCU.

[0043] The control device 100 controls various operations of the ceiling transport vehicle 1. The control device 100 controls the travel of the ceiling transport vehicle 1 by controlling the travel drive unit 2b. The control device 100 controls the lift drive unit 11. For example, the control device 100 controls the rotation of the lift motor 31 to control the winding and unwinding (lowering) of the hanging member 12. In other words, the control device 100 can control the position of the holding unit 21 in the Z direction by controlling the rotation of the lift motor 31.

[0044] The control device 100 controls the transfer operation of the container C by the ceiling transport vehicle 1. The transfer operation of the container C includes an unloading operation in which the container C is placed on a loading platform LD such as a port, and a load grasping operation in which the container C on the loading platform LD is grasped. During the unloading operation or the load grasping operation, the control device 100 controls the transfer motor 16 provided in the lateral feeding mechanism 8, thereby controlling the lateral feeding operation of the slide section 14.

[0045] The unloading operation according to this embodiment will be described below. Fig. 3 is a diagram showing a schematic diagram of the unloading operation of the ceiling transport vehicle according to this embodiment. The unloading operation is to place the container C on a predetermined placement table LD by unwinding the hanging member 12 after the lateral unloading operation.

[0046] The overhead transport vehicle 1 travels on the overhead track R, for example, with a container C stored in the storage space AS (hereinafter referred to as the "storage state"). When performing an unloading operation, the overhead transport vehicle 1 travels to a predetermined position (hereinafter referred to as the "transport position"). Then, the overhead transport vehicle 1 stops at the transport position and performs lateral transfer.

[0047] The ceiling transport vehicle 1 shown by the solid line in Figure 3 is stopped at a transport position to perform an unloading operation. In this state, the container C is stored in the storage space AS. When the ceiling transport vehicle 1 starts the unloading operation, it operates the transfer motor 16 to move the slide part 14 by a predetermined slide amount (hereinafter referred to as the "set slide amount") Ds. As a result, the holder 21, while holding the container C, moves laterally from the stored state to a predetermined transfer position TP. The set slide amount Ds is an example of a first slide amount.

[0048] The ceiling transport vehicle 1 recognizes a change in the position of the holding unit 21 based on a rotation signal from the rotation amount detection unit 17. For example, the ceiling transport vehicle 1 monitors the rotation signal from the rotation amount detection unit 17 to determine whether the sliding unit 14 has moved laterally by the set slide amount Ds. If the ceiling transport vehicle 1 determines that the sliding unit 14 has moved laterally by the set slide amount Ds, it recognizes that the holding unit 21 has moved to the transfer position TP. The sliding unit 14 shown by the dashed dotted line in Figure 2 is in a state where it has moved laterally by the set slide amount Ds. The set slide amount Ds is set in advance according to the transfer position TP. The transfer position TP is, for example, a position above the mounting table LD.

[0049] When the ceiling transport vehicle 1 moves the slide portion 14 by the slide set amount Ds, it controls the rotation of the lift motor 31 to unwind the hanging member 12, thereby lowering the holding portion 21. Then, the ceiling transport vehicle 1 releases the holding portion 21 from holding the container C while the container C is in contact with the mounting table LD, thereby allowing the container C to be placed on the mounting table LD.

[0050] 3 shows a state in which the slide portion 14 is not bent, but in reality, when a lateral dispensing operation is performed while holding a container C, the slide portion 14 may bend due to the weight of the container C. The slide portion 14 may bend due to the weight of the container C. In such a case, even if the ceiling transport vehicle 1 recognizes that the holding portion 21 has moved to the transfer position TP based on the rotation signal, it is possible that the actual position of the holding portion 21 may be deviated from the transfer position TP.

[0051] Furthermore, the amount of deflection of the slide portion 14 changes depending on the weight of the container C. Therefore, even if the ceiling transport vehicle 1 recognizes that the holder 21 has moved to the transfer position TP based on the rotation signal, there may be cases where the deviation between the actual position of the holder 21 and the transfer position TP falls outside the allowable range depending on the weight of the container C.

[0052] Furthermore, as shown in Figure 4, when the weight of container C is light, the hanging member 12 tends to extend diagonally downward from the lifting / lowering drive unit 11 toward the holding unit 21, whereas when the weight of container C is heavy, the hanging member 12 tends to extend vertically from the lifting / lowering drive unit 11 toward the holding unit 21, as shown in Figure 5. Therefore, when the weight of container C is heavy, the position of holding unit 21 may shift laterally compared to when it is light. As a result, when the weight of container C is light, the deviation between the actual position of holding unit 21 and transfer position TP is within the allowable range, but when the weight of container C is heavy, the deviation between the actual position of holding unit 21 and transfer position TP may exceed the allowable range.

[0053] In this way, when the sliding unit 14 is slid laterally during an unloading operation, the stopping position of the holding unit 21 fluctuates depending on the weight of the container C held by the holding unit 21. Therefore, when performing an unloading operation, the ceiling transport vehicle 1 of this embodiment adjusts the slide setting amount according to the weight of the container C so that the deviation between the actual position of the holding unit 21 and the transfer position TP is within an acceptable range. As an example, the ceiling transport vehicle 1 corrects the slide setting amount according to the weight of the container C and moves the sliding unit 14 by the corrected slide amount. As a result, even if the weight of the container C is large, the deviation between the actual position of the holding unit 21 and the transfer position TP is within an acceptable range, and the item can be transferred at an appropriate position even if the weight of the container C varies.

[0054] The following describes the functional units of the control device 100 according to this embodiment. As shown in FIG.

[0055] The storage unit 110 stores transfer information 50 and correction information 51. The transfer information 50 includes, for example, information indicating a slide set amount. The slide set amount is, for example, a slide amount set so that the position of the holder 21 becomes the transfer position TP when the slide unit 14 is moved while not holding a container C. The transfer information 50 may also include information on the transfer position TP. The control device 100 may, for example, receive information on the slide set amount from an external device and store the information on the slide set amount in the storage unit 110. The control device 100 may, for example, receive information on the transfer position TP from the external device, calculate a slide set amount corresponding to the transfer position TP using a predetermined formula or table, and store the calculated slide set amount in the storage unit 110.

[0056] The correction information 51 is information indicating the relationship between the weight of the container C and the correction value of the slide setting amount. For example, the correction information 51 may be table information in which the weight of the container C is associated with a correction value for correcting the slide setting amount according to the weight of the container C. The correction information 51 may also be a mathematical formula such as a function that obtains a correction value by inputting the weight of the container C. The correction information 51 may be determined, for example, experimentally or theoretically.

[0057] The correction value is a value for correcting the slide setting amount so that the deviation ΔP between the actual position of the holder 21 and the transfer position TP falls within an allowable range. FIG. 6 is a diagram schematically illustrating an example of the relationship between the mass of a container and the deviation ΔP according to the first embodiment. In the example illustrated in FIG. 6, the deviation ΔP increases in proportion to the mass of the container. That is, the deviation ΔP and the mass of the container C are proportional to each other. The correction value is a correction value for correcting the slide setting amount so that the deviation ΔP proportional to the mass of the container C is eliminated or reduced to within an allowable range. However, the relationship between the mass of the container C and the deviation ΔP illustrated in FIG. 6 is merely an example, and a nonlinear relationship, such as a quadratic change, may also be considered. For example, the relationship between the mass of the container C and the deviation ΔP may be determined by experiment or the like, and the correction value may be set based on the results.

[0058] The weight acquisition unit 120 determines the weight of the container C held by the holder 21 based on the torque of the lift motor 31 measured by the torque sensor 40. In other words, the weight acquisition unit 120 determines the weight of the container C by estimating the weight of the container C held by the holder 21 based on the torque of the lift motor 31. For example, the weight acquisition unit 120 has in advance information such as a table or function indicating the correspondence between the torque of the lift motor 31 and the weight of the container C (hereinafter referred to as "torque-weight conversion information"), and obtains the weight of the container C held by the holder 21 by determining the weight of the container corresponding to the torque of the lift motor 31 using the torque-weight conversion information.

[0059] Here, the weight acquisition unit 120 can execute a process of acquiring the weight of the container C held by the holder 21 based on the torque of the lift motor 31 (hereinafter referred to as "weight measurement process") at any timing.

[0060] For example, the weight acquisition unit 120 may execute the weight measurement process while the overhead transport vehicle 1 is holding the container C at the holding unit 21 and the overhead transport vehicle 1 is stopped. As a specific example, the weight acquisition unit 120 may execute the weight measurement process while the container C is in a stored state and the overhead transport vehicle 1 is stopped. This improves the accuracy of the measurement value of the torque sensor 40, and the weight acquisition unit 120 can acquire the weight of the container C more accurately.

[0061] 7 is a diagram showing the functional units of the control unit 130 according to the first embodiment. As shown in FIG.

[0062] The calculation unit 210 acquires a correction value corresponding to the weight of the container C acquired by the weight acquisition unit 120 from the correction information 51. The calculation unit 210 corrects the slide set amount based on the correction value acquired from the correction information 51. For example, the calculation unit 210 corrects the slide set amount by adding or subtracting the correction value acquired from the correction information 51 to or from the slide set amount. In this case, for example, the correction value is the deviation amount ΔP corresponding to the weight of the container C acquired by the weight acquisition unit 120, as shown in FIG. 6 .

[0063] The calculation unit 210 may correct the slide setting amount by, for example, multiplying or dividing the slide setting amount by a correction value (for example, a coefficient) acquired from the correction information 51. In the following description, the slide setting amount corrected by the correction value may be referred to as a "corrected slide setting amount." The corrected slide setting amount is an example of a second slide amount.

[0064] The drive control unit 220 controls the transfer motor 16 to control the lateral movement operation of the slide unit 14. The drive control unit 220 recognizes the current slide amount of the slide unit 14 based on the rotation signal from the rotation amount detection unit 17. When performing a load-grabbing operation, the drive control unit 220 moves the slide unit 14 laterally by the slide set amount. When performing an unloading operation, the drive control unit 220 moves the slide unit 14 laterally by the slide set amount corrected by the calculation unit 210, i.e., the corrected slide set amount.

[0065] The following describes the flow of the method for correcting the slide set amount in the ceiling transport vehicle 1 according to this embodiment. Fig. 8 is a flowchart of the method for correcting the slide set amount in the ceiling transport vehicle 1 according to the first embodiment.

[0066] When transporting a container C from a platform at point A to a platform at point B, the ceiling transport vehicle 1 first performs an operation of grabbing the container C placed on the platform at point A (step S101). The ceiling transport vehicle 1 performs an operation of grabbing the container C placed on the platform at point A, and then holds the container C in a suspended state by the holding unit 21 rising as a result of the lifting drive unit 11 winding up the hanging member 12 (step S102).

[0067] With the container C suspended, the torque sensor 40 measures the torque of the lift motor 31 and outputs the measured torque to the control device 100. The weight acquisition unit 120 estimates the weight of the container C held by the holder 21 based on the torque of the lift motor 31 (step S103). For example, the processing of step S102 may be executed while the holder 21 is rising, or may be executed when the holder 21 has completed rising and the container C is in a stored state. When the processing of step S102 is completed, the ceiling transport vehicle 1 starts traveling toward the platform at point B.

[0068] The control unit 130 acquires a correction value corresponding to the weight of the container C estimated in step S102 from the correction information 51 (step S104). Then, the control unit 130 acquires a corrected slide set amount by correcting the slide set amount with the acquired correction value (step S105). When performing an unloading operation on the platform at point B, the control unit 130 moves the slide unit 14 by the corrected slide set amount (step S106). This makes it possible to keep the deviation ΔP between the holder 21 and the transfer position TP within an allowable range even if the weight of the container C varies. Therefore, the ceiling transport vehicle 1 can transfer the item at an appropriate position even if the weight of the container C varies.

[0069] (Second embodiment) In the first embodiment, the control unit 130 calculates the slide amount by which the sliding unit 14 is moved by correcting the slide set amount, but this is not limited to this. For example, the control unit 130A according to the second embodiment directly calculates the slide amount by which the sliding unit 14 is moved during the unloading operation from the weight of the container C. FIG. 9 is a diagram showing a schematic electrical configuration of the ceiling transport vehicle according to the second embodiment. Note that the ceiling transport vehicle according to the second embodiment may be the same as the first embodiment in other respects, except for the method of calculating the slide amount by which the sliding unit 14 is moved during the unloading operation.

[0070] The storage unit 110A stores information (hereinafter referred to as "slide amount calculation information") indicating the relationship between the weight of the container C and the slide amount at which the amount of deviation ΔP caused by that weight is within an allowable range. The slide amount calculation information may be table information in which the weight of the container C is associated with the slide amount, or may be a mathematical formula such as a function that, when the weight of the container C is input, obtains the slide amount corresponding to that weight. The slide amount calculation information may be determined, for example, experimentally or theoretically.

[0071] When performing an unloading operation, the control unit 130A acquires the weight of the container C from the weight acquisition unit 120 and acquires the slide amount corresponding to the acquired weight of the container C from the slide amount calculation information. Then, when performing an unloading operation, the control unit 130A moves the slide unit 14 by the slide amount acquired from the slide amount calculation information. As a result, even if the weight of the container C fluctuates, the amount of deviation ΔP between the holder 21 and the transfer position TP can be kept within the allowable range, and the item can be transferred at an appropriate position even if the weight of the container C varies.

[0072] (Third embodiment) In the first embodiment, the control unit 130 calculated the corrected slide set amount by correcting the slide set amount with one correction value, but this is not limited to this. For example, the control unit 130B according to the third embodiment calculates the corrected slide set amount by correcting the slide set amount with multiple correction values. FIG. 10 is a diagram showing the schematic electrical configuration of the ceiling transport vehicle according to the third embodiment. Note that the ceiling transport vehicle according to the third embodiment differs from the first embodiment in the method of correcting the slide amount by which the slide section 14 is moved during the unloading operation, but may be the same as the first embodiment in other respects.

[0073] For example, transfer information 50, a first correction value 60, and correction information 61 are stored in the storage unit 110B.

[0074] The first correction value 60 is a constant. The first correction value 60 is a value for correcting the slide setting amount when the holder 21 holds the container C, regardless of the weight of the container C.

[0075] The correction information 61 is information indicating the relationship between the weight of the container C and the second correction value of the slide set amount. For example, the correction information 61 may be table information in which the weight of the container C is associated with the second correction value for correcting the slide set amount according to the weight of the container C. The correction information 61 may also be a mathematical formula such as a function that obtains the second correction value by inputting the weight of the container C. The correction information 61 may be determined, for example, experimentally or theoretically. The second correction value is a value for correcting the slide set amount so that the deviation ΔP between the actual position of the holder 21 and the transfer position TP falls within an allowable range.

[0076] 11 is a diagram illustrating a method for correcting a slide set amount according to the third embodiment. When the weight of container C acquired by weight acquisition unit 120 is within a first range, control unit 130B corrects the slide set amount by a first correction value 60. The first range is a range of weights of container C indicating that the weight of container C is small. When the weight of container C is within the first range, control unit 130B corrects the slide set amount by the first correction value 60, which is a constant, thereby making it possible to keep the deviation amount ΔP within an allowable range.

[0077] When the weight of the container C acquired by the weight acquisition unit 120 is within a second range different from the first range, the control unit 130B corrects the slide setting amount with a second correction value. The second range is a range of weights of the container C that is higher than the first range and indicates that the weight of the container C is large. When the weight of the container C is within the second range, the control unit 130B corrects the slide setting amount with a second correction value that changes depending on the weight of the container C, thereby making it possible to keep the deviation amount ΔP within an acceptable range. Specifically, when the weight of the container C is within the second range, the control unit 130B acquires a second correction value corresponding to the weight of the container C acquired by the weight acquisition unit 120 from the correction information 61, as in the first embodiment. Then, the control unit 130B corrects the slide setting amount based on the second correction value acquired from the correction information 61.

[0078] The second correction value in the correction information 61 may be a value that takes into account the first correction value 60. FIG. 12 is a diagram illustrating a modified example of the slide set amount correction method according to the third embodiment. When the ceiling transport vehicle 1 holds a container C, the control unit 130B corrects the slide set amount by the first correction value 60, regardless of the weight of the container C. Then, when the weight of the container C acquired by the weight acquisition unit 120 is within a predetermined range, the control unit 130B further corrects the slide set amount by a second correction value that changes depending on the weight of the container C. That is, when the weight of the container C acquired by the weight acquisition unit 120 is within a predetermined range, the control unit 130B further corrects the slide set amount corrected by the first correction value 60 by the second correction value. The predetermined range corresponds to the second range described above. This allows the deviation amount ΔP to be within the allowable range even when the weight of the container C fluctuates.

[0079] In the first, second, and third embodiments, the weight acquisition unit 120 estimates the weight of the container C from the torque of the lifting motor 31, but this is not limiting. For example, in the first, second, and third embodiments, the weight acquisition unit 120 may acquire data on the weight of the container C from an external device (e.g., an external controller) other than the ceiling transport vehicle 1 via wired or wireless communication. Furthermore, in the first, second, and third embodiments, the weight acquisition unit 120 may estimate the weight of the container C using the output of a sensor other than a torque sensor.

[0080] The above embodiment discloses the following configuration. (Configuration 1) The overhead transport vehicle 1 holds a container C and transports it by traveling on the ceiling track R. The overhead transport vehicle 1 is equipped with a holding unit 21 that holds the container C, a lifting device 7 that raises and lowers the holding unit 21 that has moved to the transfer position, a lateral delivery mechanism 8 that moves the holding unit 21 to the transfer position by sliding it to the side of the ceiling track R, an acquisition unit (120) that acquires the weight of the container C held by the holding unit 21, and a control unit 130 that controls the slide amount of the lateral delivery mechanism 8. The control units 130, 130A, 130B change the slide amount depending on the weight of the container C acquired by the acquisition unit. (Configuration 2) In the configuration 1, the ceiling transport vehicle 1 includes memory units 110, 110A, and 110B that store a first slide amount, which is a slide amount corresponding to the position of the placement unit to which the container C is transferred. The control units 130, 130A, and 130B may slide the lateral delivery mechanism 8 by a second slide amount obtained by correcting the first slide amount according to the weight of the container C acquired by the acquisition unit. (Configuration 3) In configuration 1 or 2, a lift motor 31 is provided for lifting and lowering the holder 21. The acquisition unit may acquire the weight of the container C held by the holder 21 by measuring the weight of the container C based on the torque of the lift motor. (Configuration 4) In the configuration 1 or 2, the acquisition unit may include a sensor that measures the weight of the container C held by the holder 21. (Configuration 5) In any of the configurations 1 to 4, the acquisition unit may measure the weight of the container C while the ceiling transport vehicle 1 is holding the container C at the holding unit 21 and while the ceiling transport vehicle 1 is stopped. (Configuration 6) In any of configurations 1 to 5, the ceiling transport vehicle 1 transports the container C by raising the holding unit 21 holding the container C with the lifting motor 31 to place the container C in a predetermined space and traveling with the container C placed in the predetermined space. The acquisition unit may measure the weight of the container C while the container C is placed in the predetermined space and the ceiling transport vehicle 1 is stopped. (Configuration 7) In the configuration 1 or 2, the weight acquisition unit 120 may acquire data on the weight of the container C held by the holder 21 from an external controller via wired or wireless communication. (Configuration 8) In any of configurations 1 to 7, the storage unit 110, 110B stores correction information indicating the relationship between the weight of the container C and a correction value for the slide amount. The control unit 130, 130B may acquire a correction value corresponding to the weight of the container C acquired by the acquisition unit from the correction information, and correct the first slide amount based on the acquired correction value. (Configuration 9) In any of configurations 1 to 8, the control unit 130B may correct the first slide amount based on a first correction value, which is a constant independent of the weight of the item, and a second correction value corresponding to the weight of the container C acquired by the acquisition unit.

[0081] One or more of the requirements described in the above-described embodiments may be omitted. Furthermore, the requirements described in the above-described embodiments may be combined as appropriate. Furthermore, the execution order of each procedure shown in this embodiment may be realized in any order, as long as the results of a previous procedure are not used in a subsequent procedure. Furthermore, even if the operations in the above-described embodiments are described using terms such as "first," "next," and "followed" for convenience, it is not essential that they be performed in this order. [Explanation of symbols]

[0082] 1 Ceiling transport vehicle, 8 Lateral delivery mechanism, 21 Holding unit, 130, 130A, 130B Control unit, 110, 110A, 110B Storage unit

Claims

1. A transport vehicle that carries an item and travels on a track, a holding portion for holding the article; a lateral delivery mechanism that moves the holding unit to a transfer position by sliding laterally along the track; an elevating device that elevates the holding unit that has moved to the transfer position; an acquisition unit that acquires the weight of the item held by the holding unit; a control unit that controls the slide amount of the lateral feed mechanism, The control unit changes the slide amount according to the weight of the item acquired by the acquisition unit.

2. a storage unit configured to store a first slide amount corresponding to a position of the placement unit onto which the article is transferred; The transport vehicle according to claim 1 , wherein the control unit slides the lateral feeding mechanism by a second slide amount obtained by correcting the first slide amount in accordance with the weight of the item acquired by the acquisition unit.

3. a lifting motor for lifting and lowering the holding unit; the acquisition unit acquires the weight of the item held by the holding unit by measuring the weight of the item based on the torque of the lifting motor. The transport vehicle according to claim 2 .

4. the acquisition unit includes a sensor for measuring the weight of the item held by the holding unit; The transport vehicle according to claim 2 .

5. The transport vehicle according to claim 1 , wherein the acquisition unit measures the weight of the item while the transport vehicle is holding the item in the holding unit and while the transport vehicle is stopped.

6. the transport vehicle raises the holding unit holding the item to store the item in a predetermined space, and travels with the item stored in the predetermined space to transport the item; The transport vehicle according to claim 5 , wherein the acquisition unit measures the weight of the item while the item is contained in the predetermined space and the transport vehicle is stopped.

7. The acquisition unit acquires data on the weight of the item held by the holding unit from an external controller via wired communication or wireless communication. The transport vehicle according to claim 2 .

8. the storage unit stores correction information indicating a relationship between the weight of the article and a correction value of the slide amount, The transport vehicle according to claim 2 , wherein the control unit acquires the correction value corresponding to the weight of the item acquired by the acquisition unit from the correction information, and corrects the first slide amount based on the acquired correction value.

9. The transport vehicle described in claim 2, wherein the control unit corrects the first slide amount based on a first correction value that is a constant independent of the weight of the item and a second correction value that corresponds to the weight of the item acquired by the acquisition unit.

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