Conveyance device

Abstract

To provide a conveyance device capable of suppressing a decrease in efficiency of conveyance of a conveyance object by a travel cart.SOLUTION: A conveyance device comprises a travel cart, a mast, an elevation part, and a control part. The travel cart is provided with a plurality of drive units each having wheels, a motor driving the wheels, and a slip detection part detecting a wheel slip. The control part stops the travel cart (S4) when at least two slip detection parts among the plurality of slip detection parts detect a slip of a predetermined quantity or more (S2: YES), at least in a state in which the travel cart is accelerated.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a conveying device that conveys an object. [Background technology]

[0002] Conventionally, in automated warehouses, articles are transported by stacker cranes, and it is known that slippage occurs in the wheels of the traveling carriages of stacker cranes (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-254912 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, for example, if control is performed to stop the traveling carriage when slippage occurs in either the front or rear wheels of the traveling carriage, there is a problem that the efficiency of transporting the transported object by the traveling carriage decreases.

[0005] An object of one aspect of the present disclosure is to provide a conveying device that can suppress a decrease in the efficiency of conveying an object by a traveling carriage. [Means for solving the problem]

[0006] In order to solve the above problems, a conveyance device according to one aspect of the present disclosure includes a traveling carriage that travels along a track, a mast erected on the traveling carriage, an elevator that holds an object to be conveyed and moves up and down along the mast, and a control unit. The traveling carriage is provided with a plurality of drive units, each drive unit having wheels that roll on the track, a motor that drives the wheels, and a slippage detection unit that detects slippage of the wheels. The control unit stops the traveling carriage when two or more of the plurality of slippage detection units detect slippage of a predetermined amount or more while the traveling carriage is at least accelerating. [Effects of the Invention]

[0007] According to one aspect of the present disclosure, it is possible to suppress a decrease in the efficiency of transporting an object by a traveling carriage. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a front view of a stacker crane according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing the electrical configuration of the stacker crane according to the embodiment. [Figure 3] FIG. 2 is a block diagram showing the electrical configuration of a driving control unit according to the embodiment. [Figure 4] 10 is a flowchart showing an example of the flow of a slippage detection process performed by the control device according to the embodiment. [Figure 5] 10 is a flowchart showing an example of the flow of a sensor abnormality detection process performed by a traveling control unit according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to FIGS.

[0010] [Stacker crane schematic configuration] Fig. 1 is a front view of a stacker crane 1. The stacker crane 1 is an example of a transport device that transports objects in an automated warehouse or the like. As shown in Fig. 1, the stacker crane 1 includes a traveling carriage 10, a pair of masts 11, a lifting unit 12, and a transfer device 13.

[0011] For ease of explanation, the up-down direction and the front-to-rear direction of the stacker crane 1 are defined as shown by the arrows in Fig. 1. The front side of the paper in Fig. 1 is defined as the right side of the stacker crane 1, and the back side of the paper in Fig. 1 is defined as the left side of the stacker crane 1. The up-down direction of the stacker crane 1 corresponds to the direction in which the lifting unit 12 moves up and down. The front-to-rear direction of the stacker crane 1 corresponds to the direction in which the traveling cart 10 travels.

[0012] The traveling bogie 10 travels in a traveling direction, i.e., a forward and backward direction, along a track. The track is formed by a traveling rail R1. The traveling bogie 10 has a first wheel 21a and a second wheel 21b. The traveling bogie 10 travels on the traveling rail R1 as the first wheel 21a and the second wheel 21b rotate. The first wheel 21a and the second wheel 21b are an example of wheels that roll on the track.

[0013] The first wheel 21a is disposed on the front side of the traveling carriage 10. The second wheel 21b is disposed on the rear side of the traveling carriage 10. The first wheel 21a is driven by a first traveling motor 28a. The second wheel 21b is driven by a second traveling motor 28b. The first traveling motor 28a and the second traveling motor 28b are examples of motors that drive wheels.

[0014] A pair of masts 11 are erected on the upper part of the traveling carriage 10. The masts 11 are spaced apart in the front-to-rear direction and extend in the up-down direction. Each mast 11 is formed of a vertically long hollow member.

[0015] The upper ends of the pair of masts 11 are connected by an upper frame 14. The upper frame 14 has guide rollers 15. The guide rollers 15 are guided by guide rails R2 fixed to the ceiling (not shown). The upper frame 14 is configured to be movable in the front-to-rear direction while being guided by the guide rails R2.

[0016] The lifting unit 12 is supported by a pair of masts 11 and moves up and down along the masts 11. The lifting unit 12 is supported by being suspended by four wires 20 wound around a rotating body 23. One lifting motor 22 is provided at the front of the traveling carriage 10. The lifting motor 22 is driven to rotate the rotating body 23 forward and backward, thereby winding or unwinding the wire 20, causing the lifting unit 12 to move up and down along the masts 11. Two lifting motors 22 may be provided, one at the front and one at the rear of the traveling carriage 10.

[0017] The transfer device 13 is supported by the lifting section 12. The transfer device 13 has a fork mechanism (not shown) that holds the transported object M. The transfer device 13 places the transported object M at a predetermined transfer position in a storage section (not shown) by moving the fork mechanism out and back.

[0018] The traveling carriage 10 is provided with a lifting sensor 26. The lifting sensor 26 detects the vertical position of the lifting unit 12. The lifting sensor 26 emits laser light in the vertical direction toward a reflector 26a arranged on the underside of the lifting unit 12, and receives the light reflected by the reflector 26a to detect the distance to the lifting unit 12, thereby detecting the vertical position of the lifting unit 12. Note that although a laser-type distance sensor is used as the lifting sensor 26, this is not limiting and a barcode-type distance meter may also be used.

[0019] The traveling carriage 10 is also provided with a traveling sensor 29. The traveling sensor 29 is an example of a position detection unit that detects the position of the traveling carriage 10 along the track. The traveling sensor 29 emits laser light along the longitudinal direction of the traveling rail R1 toward a reflector 29a arranged at one end of the traveling rail R1, and receives the light reflected by the reflector 29a to detect the distance to the reflector 29a, thereby detecting the position of the traveling carriage 10.

[0020] [Stacker crane electrical configuration] Next, the electrical configuration of the stacker crane 1 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the electrical configuration of the stacker crane 1. As shown in Fig. 2, the stacker crane 1 further includes a first notification unit 24, a second notification unit 25, a first encoder 27a, a second encoder 27b, and a control device 30.

[0021] The first notification unit 24 is a component for notifying the user that slippage has occurred in the first wheel 21a when slippage of the first wheel 21a is detected by the first slippage detection unit 34. The first notification unit 24 is configured to have, for example, a speaker that outputs sound and a display that displays error codes and the like.

[0022] The second notification unit 25 is a component for notifying the user that slippage has occurred in the second wheel 21b when slippage of the second wheel 21b is detected by the second slippage detection unit 35. The second notification unit 25 is configured to have, for example, a speaker that outputs sound and a display that displays error codes and the like.

[0023] The first encoder 27a is, for example, a rotary encoder that is disposed near the first running motor 28a and detects the rotation speed of the first running motor 28a. The first encoder 27a outputs a signal corresponding to the rotation speed of the first running motor 28a to the first slip detection unit 34.

[0024] The second encoder 27b is, for example, a rotary encoder that is disposed near the second travel motor 28b and detects the rotation speed of the second travel motor 28b. The second encoder 27b outputs a signal corresponding to the rotation speed of the second travel motor 28b to the second slip detection unit 35.

[0025] The control device 30 has a travel control unit 31, a lifting control unit 32, a transfer control unit 33, a first slippage detection unit 34, and a second slippage detection unit 35, and controls the operation of each part of the stacker crane 1.

[0026] The traveling control unit 31 is an example of a control unit that controls the traveling operation of the traveling carriage 10. The traveling control unit 31 controls the driving of the first traveling motor 28a and the second traveling motor 28b based on the detection result of the traveling sensor 29, thereby controlling the traveling operation of the traveling carriage 10.

[0027] The lifting control unit 32 controls the lifting operation of the lifting unit 12 by controlling the drive of the lifting motor 22 based on the detection results of the lifting sensor 26, and moves the transfer device 13 to the desired stopping position in the vertical direction.

[0028] The transfer control unit 33 controls the fork mechanism to control the transfer operation of the transfer device 13. In this way, the control device 30 controls the traveling operation of the traveling carriage 10, the lifting operation of the lifting unit 12, and the transfer operation of the transfer device 13 to carry the transported article M into or out of the storage unit.

[0029] The first slippage detection unit 34 detects slippage of the first wheel 21a based on the rotation speed of the first running motor 28a detected by the first encoder 27a and the amount of change in position in the running direction of the running cart 10 detected by the running sensor 29.

[0030] The second slippage detection unit 35 detects slippage of the second wheel 21b based on the rotation speed of the second running motor 28b detected by the second encoder 27b and the amount of change in position in the running direction of the running cart 10 detected by the running sensor 29.

[0031] The first wheel 21a, the first notification unit 24, the first encoder 27a, the first running motor 28a, and the first slippage detection unit 34 constitute a first drive unit 41. The second wheel 21b, the second notification unit 25, the second encoder 27b, the second running motor 28b, and the second slippage detection unit 35 constitute a second drive unit 42. The first wheel 21a of the first drive unit 41 and the second wheel 21b of the second drive unit 42 are arranged at different positions in the running direction of the traveling carriage 10.

[0032] [Electrical configuration of driving control unit] Next, the electrical configuration of the traveling control unit 31 will be described in detail with reference to Fig. 3. Fig. 3 is a block diagram showing the electrical configuration of the traveling control unit 31. As shown in Fig. 3, the traveling control unit 31 has a synchronization control unit 36, a first servo amplifier 37, and a second servo amplifier 38.

[0033] The synchronization control unit 36 ​​receives an abnormality signal from the first slip detection unit 34 indicating that slip has occurred in the first wheel 21a, and receives an abnormality signal from the second slip detection unit 35 indicating that slip has occurred in the second wheel 21b.

[0034] The synchronization control unit 36 ​​also determines the travel pattern of the traveling vehicle 10 based on the distance between the position of the traveling vehicle 10 in the traveling direction detected by the travel sensor 29 and the target stopping position. The travel patterns include an acceleration state, a constant speed state, and a deceleration state.

[0035] The synchronization control unit 36 ​​transmits traveling speed command information that commands a target traveling speed according to the traveling pattern to the first servo amplifier 37. The first servo amplifier 37 operates the first traveling motor 28a based on the difference between the traveling speed calculated from the change in traveling position per unit time detected by the traveling sensor 29 and the target traveling speed from the synchronization control unit 36.

[0036] The first servo amplifier 37 determines a torque command value so as to make the difference between the above-mentioned running speed and the target running speed zero, and controls the rotation of the first running motor 28a by supplying a current according to the torque command value to the first running motor 28a.

[0037] The first servo amplifier 37 provides the determined torque command value to the second servo amplifier 38. Based on the torque command value from the first servo amplifier 37, the second servo amplifier 38 supplies a current corresponding to the torque command value to the second traveling motor 28b, thereby controlling the rotation of the second traveling motor 28b.

[0038] [Slip detection process by the control device] Next, the flow of the slippage detection process performed by the control device 30 will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of the flow of the slippage detection process performed by the control device 30.

[0039] 4, first, the first slippage detection unit 34 of the control device 30 determines whether or not a predetermined amount of slippage or more of the first wheel 21a has been detected (S1). In step S1, the first slippage detection unit 34 performs a threshold determination to determine whether or not the difference between the travel distance of the traveling carriage 10 calculated based on the rotation speed of the first traveling motor 28a detected by the first encoder 27a and the amount of change in position in the traveling direction of the traveling carriage 10 detected by the traveling sensor 29 is equal to or greater than a predetermined threshold.

[0040] Then, the first slippage detection unit 34 determines that a predetermined amount of slippage or more has occurred in the first wheel 21a when the difference between the calculated travel distance of the traveling carriage 10 and the amount of change in position of the traveling carriage 10 in the traveling direction is greater than or equal to a predetermined threshold value.

[0041] The first slippage detection unit 34 performs the threshold determination every time the first travel motor 28a makes a predetermined number of rotations, for example, every two rotations. Here, the travel distance of the traveling carriage 10 based on two rotations of the first travel motor 28a is defined as L1 (mm). For example, if the difference between the travel distance L1 (mm) of the traveling carriage 10 and the amount of change in position of the traveling carriage 10 in the traveling direction detected by the travel sensor 29 is 0.4 × L1 (mm) or more, the first slippage detection unit 34 determines that a slippage of a predetermined amount or more has occurred in the first wheel 21a.

[0042] This makes it possible to detect the occurrence of slippage of the first wheel 21a of a predetermined amount or more at an early stage. Also, by appropriately setting the threshold value for the threshold determination, it becomes possible to more quickly detect the occurrence of slippage of the first wheel 21a of a predetermined amount or more.

[0043] If the first slippage detection unit 34 has not detected a slippage of the first wheel 21a of the predetermined amount or more (S1: NO), it repeats step S1. On the other hand, if the first slippage detection unit 34 has detected a slippage of the first wheel 21a of the predetermined amount or more (S1: YES), it determines whether the second slippage detection unit 35 has detected a slippage of the second wheel 21b of the predetermined amount or more (S2).

[0044] In step S2, the second slip detection unit 35 performs a threshold determination to determine whether the difference between the travel distance of the traveling carriage 10 calculated based on the rotation speed of the second traveling motor 28b detected by the second encoder 27b and the amount of change in position in the traveling direction of the traveling carriage 10 detected by the traveling sensor 29 is greater than or equal to a predetermined threshold.

[0045] Then, the second slippage detection unit 35 determines that a predetermined amount of slippage or more has occurred in the second wheel 21b when the difference between the calculated travel distance of the traveling carriage 10 and the amount of change in position of the traveling carriage 10 in the traveling direction is greater than or equal to a predetermined threshold value.

[0046] The second slippage detection unit 35 performs the threshold determination every time the second travel motor 28b makes a predetermined number of rotations, for example, two rotations. Here, the travel distance of the traveling carriage 10 based on two rotations of the second travel motor 28b is set to L2 [mm]. For example, if the difference between the travel distance L2 [mm] of the traveling carriage 10 and the amount of change in position of the traveling carriage 10 in the traveling direction detected by the travel sensor 29 is 0.4 × L2 [mm] or more, the second slippage detection unit 35 determines that a predetermined amount or more of slippage has occurred in the second wheel 21b.

[0047] This makes it possible to detect the occurrence of slippage of the second wheel 21b of a predetermined amount or more at an early stage. Also, by appropriately setting the threshold value for the threshold determination, it becomes possible to more quickly detect the occurrence of slippage of the second wheel 21b of a predetermined amount or more.

[0048] If the second slip detection unit 35 does not detect slippage of the second wheel 21b of the predetermined amount or more (S2: NO), the process returns to step S1. On the other hand, if the traveling control unit 31 detects slippage of the second wheel 21b of the predetermined amount or more (S2: YES), the traveling control unit 31 controls the first servo amplifier 37 to stop the rotation of the first traveling motor 28a (S3).

[0049] After step S3, the traveling control unit 31 controls the second servo amplifier 38 to stop the rotation of the second traveling motor 28b (S4). This stops the traveling carriage 10. This completes the slip detection process by the traveling control unit 31 shown in FIG.

[0050] In this way, the traveling control unit 31 will stop the traveling carriage 10 when all slippage detection units, i.e., the first slippage detection unit 34 and the second slippage detection unit 35, detect slippage of a predetermined amount or more, at least when the traveling carriage 10 is accelerated.

[0051] [Flow of sensor abnormality detection process by driving control unit] Next, the flow of the sensor abnormality detection process performed by the traveling control unit 31 will be described with reference to Fig. 5. Fig. 5 is a flowchart showing an example of the flow of the sensor abnormality detection process performed by the traveling control unit 31. In this embodiment, the sensor abnormality detection process shown in Fig. 5 is executed, for example, at predetermined time intervals.

[0052] 5, first, the traveling control unit 31 determines whether the traveling vehicle 10 is traveling or not (S11). In step S11, the traveling control unit 31 determines whether the traveling vehicle 10 is traveling or not based on the rotation of the first traveling motor 28a and the second traveling motor 28b detected by the first encoder 27a and the second encoder 27b.

[0053] If the first encoder 27a and the second encoder 27b do not detect rotation of the first running motor 28a and the second running motor 28b, the running control unit 31 determines that the running carriage 10 is not running (S11: NO) and returns to step S11.

[0054] On the other hand, when the first encoder 27a and the second encoder 27b detect the rotation of the first running motor 28a and the second running motor 28b, the running control unit 31 determines that the running carriage 10 is running (S11: YES), and determines whether the position of the running carriage 10 detected by the running sensor 29 has changed (S12).

[0055] If the position of the traveling carriage 10 detected by the traveling sensor 29 changes (S12: YES), the traveling control unit 31 determines that the traveling sensor 29 is operating normally, and returns to step S11.

[0056] On the other hand, if the position of the traveling carriage 10 detected by the traveling sensor 29 does not change (S12: NO), the traveling control unit 31 determines that an abnormality has occurred in the traveling sensor 29 (S13), and stops the rotation of the first traveling motor 28a and the second traveling motor 28b, thereby stopping the traveling carriage 10 (S14). This ends the sensor abnormality detection process shown in Fig. 5.

[0057] In the stacker crane 1 of this embodiment described above, the traveling control unit 31 stops the traveling carriage 10 (S4) only when all of the first slippage detection unit 34 and the second slippage detection unit 35 detect slippage of a predetermined amount or more (S2: YES).

[0058] Here, in the stacker crane 1, the mast 11 is erected on the traveling carriage 10, so that the traveling carriage 10 is prone to tilt in the traveling direction when accelerating, and while the wheels on the front side of the traveling carriage 10 in the traveling direction are prone to slippage, the wheels on the rear side in the traveling direction are less likely to slip due to the greater load on them.

[0059] When transporting an object M using a stacker crane 1 having such a structure, even if slippage occurs on one of the first wheel 21a or the second wheel 21b, the traveling carriage 10 can still travel using the other wheel, thereby avoiding unnecessary stopping of the traveling carriage 10 and suppressing a decrease in the efficiency of transporting the object M by the stacker crane 1.

[0060] Furthermore, the first wheel 21a, which is the wheel of the first drive unit 41, is arranged on the front side of the traveling carriage 10, and the second wheel 21b, which is the wheel of the second drive unit 42, is arranged on the rear side of the traveling carriage 10. By arranging the first wheel 21a and the second wheel 21b in different positions in the traveling direction of the traveling carriage 10 in this way, it is possible to prevent the stacker crane 1, in which the mast 11 is erected on the traveling carriage 10, from tilting in the traveling direction during acceleration.

[0061] Furthermore, when the traveling control unit 31 determines in the sensor abnormality detection process shown in FIG. 5 that an abnormality such as a breakdown has occurred in the traveling sensor 29 (S13), it stops the traveling carriage 10 (S14).

[0062] If an abnormality occurs in the travel sensor 29, there will be no change in the travel speed calculated from the change in travel position per unit time detected by the travel sensor 29. In this case, the first servo amplifier 37 will supply excessive current to the first travel motor 28a in an attempt to bring the travel speed closer to the target travel speed, causing the rotation speed of the first travel motor 28a to become too high, resulting in excessive acceleration of the traveling carriage 10.

[0063] Therefore, in this embodiment, the traveling control unit 31 stops the traveling carriage 10 when it determines that an abnormality has occurred in the traveling sensor 29, thereby preventing the traveling carriage 10 from being excessively accelerated. This ensures safety when the stacker crane 1 transports the transported object M.

[0064] Other embodiments In the above-described embodiment, the traveling bogie 10 is provided with two drive units, the first drive unit 41 and the second drive unit 42. However, this is not limiting and, for example, four drive units may be provided. In this case, the traveling bogie 10 may be stopped when all of the slippage detection units of the four drive units detect a predetermined amount or more of slippage in each wheel. Furthermore, for example, the traveling bogie 10 may be stopped when the slippage detection units of two or more of the four drive units detect a predetermined amount or more of slippage in each wheel.

[0065] In the above embodiment, the traveling sensor 29, which is a laser distance sensor, is used as the position detection unit that detects the position of the traveling carriage 10 along the track, but this is not limiting. For example, a barcode-type distance meter that includes a barcode extending along the track and a reading unit that is disposed on the traveling carriage 10 and reads the barcode may be used as the position detection unit.

[0066] Alternatively, a magnetic force detection type rangefinder may be used as the position detector, which has magnet parts with alternating north and south poles arranged at predetermined intervals along the track and detects the position of the traveling carriage 10 on the track based on detecting changes in the magnetic force of the magnet parts. Furthermore, a rangefinder having a scale arranged on the traveling rail R1 and an encoder arranged on the traveling carriage 10 to detect the scale may be used as the position detector.

[0067] In the above embodiment, the traveling control unit 31 is configured to stop the traveling carriage 10 when all of the slippage detection units detect a slippage of a predetermined amount or more while the traveling carriage 10 is at least accelerating, but this is not limited to this. For example, the traveling control unit 31 may stop the traveling carriage 10 when all of the slippage detection units detect a slippage of a predetermined amount or more while the traveling carriage 10 is traveling at a constant speed or while the traveling carriage 10 is decelerating.

[0068] Furthermore, in the above-described embodiment, the first slippage detection unit 34 detects slippage of the first wheel 21a based on the rotation speed of the first traveling motor 28a detected by the first encoder 27a and the amount of change in the position of the traveling carriage 10 in the traveling direction detected by the traveling sensor 29, but this is not limiting. For example, the first slippage detection unit 34 may detect slippage of the first wheel 21a by determining whether the difference between the traveling distance of the traveling carriage 10 calculated based on the torque command value from the first servo amplifier 37 and the amount of change in the position of the traveling carriage 10 detected by the traveling sensor 29 is equal to or greater than a predetermined value.

[0069] Furthermore, in the above embodiment, the traveling carriage 10 is stopped when the position of the traveling carriage 10 in the traveling direction detected by the traveling sensor 29 does not change while the traveling carriage 10 is traveling, but this is not limiting. For example, a torque sensor that detects the torque applied to the second wheel 21b may be provided, and the traveling carriage 10 may be stopped when the torque detected by the torque sensor is equal to or greater than a predetermined threshold. This prevents the second traveling motor 28b from rotating too much and generating heat.

[0070] In the above embodiment, the first servo amplifier 37 performs torque control to obtain a torque command value so as to make the difference between the traveling speed and the target traveling speed zero, but the present invention is not limited to this. The first servo amplifier 37 may perform proportional-integral control to perform proportional control and integral control based on the difference between the traveling speed and the target traveling speed.

[0071] 〔summary〕 A conveying device according to a first aspect of the present disclosure includes a traveling carriage that travels along a track, a mast erected on the traveling carriage, an elevating unit that holds an object to be conveyed and moves up and down along the mast, and a control unit. The traveling carriage is provided with a plurality of drive units, each drive unit having wheels that roll on the track, a motor that drives the wheels, and a slippage detection unit that detects slippage of the wheels. The control unit stops the traveling carriage when, at least while the traveling carriage is accelerating, two or more of the plurality of slippage detection units detect slippage of a predetermined amount or more.

[0072] According to the above configuration, by providing multiple wheels, even if one wheel slips, the carriage can continue to travel using the remaining wheels, and the carriage is stopped only when slippage is detected on two or more wheels. This reduces the frequency with which the carriage stops, and prevents a decrease in the efficiency of transporting objects by the transport device.

[0073] In a conveying device according to aspect 2 of the present disclosure, in aspect 1 above, the control unit may stop the traveling carriage when all of the slippage detection units detect a slippage of a predetermined amount or more while the traveling carriage is at least in a state where the traveling carriage is accelerated.

[0074] According to the above-mentioned configuration, the traveling carriage is stopped only when slippage is detected in all of the wheels, thereby minimizing the frequency with which the traveling carriage stops and further suppressing a decrease in the efficiency of transporting transported items by the transport device.

[0075] The conveying device according to a third aspect of the present disclosure is the one according to the first or second aspect, further comprising a position detection unit that detects a position of the traveling carriage along the track. The slippage detection unit may detect the slippage based on the number of rotations of the motor and the amount of change in the position detected by the position detection unit.

[0076] According to the above-described configuration, the slippage detection unit can detect slippage based on the number of rotations of the motor and the amount of change in position detected by the position detection unit, so that the traveling carriage can be stopped at the desired timing.

[0077] In a conveying device according to aspect 4 of the present disclosure, in aspect 3 above, the slippage detection unit may perform a threshold determination as to whether the difference between the travel distance of the traveling carriage calculated based on the rotation speed of the motor and the amount of change in position detected by the position detection unit is greater than or equal to a predetermined threshold, and may determine that slippage of greater than or equal to the predetermined amount has occurred if the difference is greater than or equal to the threshold.

[0078] According to the above-described configuration, by appropriately setting the threshold value for threshold determination, it is possible to quickly detect the occurrence of wheel slippage.

[0079] In a conveyance device according to a fifth aspect of the present disclosure, in any one of the first to fourth aspects, the plurality of drive units include a first drive unit and a second drive unit. The wheels of the first drive unit and the wheels of the second drive unit may be disposed at different positions on the traveling carriage in the traveling direction of the traveling carriage.

[0080] According to the above-mentioned configuration, by arranging the wheels of the first drive unit and the wheels of the second drive unit at different positions in the traveling direction of the traveling carriage, it is possible to prevent the conveying device from tilting in the traveling direction when accelerating, and effectively prevent a decrease in the transportation efficiency of the transported items.

[0081] In a conveying device according to aspect 6 of the present disclosure, in any of aspects 1 to 5 above, if the position detected by the position detection unit does not change when the traveling carriage is traveling due to the rotation of the motor of the drive unit, the control unit may determine that an abnormality has occurred in the position detection unit and stop the traveling carriage.

[0082] According to the above configuration, when the control unit determines that an abnormality has occurred in the position detection unit, the control unit stops the traveling carriage, thereby preventing the traveling carriage from being excessively accelerated and improving the safety of the conveyance device.

[0083] In the conveyance device according to a seventh aspect of the present disclosure, in the third aspect, the slippage detection unit may perform the threshold determination every time the motor makes a predetermined number of rotations.

[0084] According to the above-described configuration, the occurrence of slippage of each wheel can be detected at an early stage by performing a threshold determination each time the motor makes a predetermined number of revolutions.

[0085] In a conveying device according to aspect 8 of the present disclosure, in any of aspects 1 to 7 above, the drive unit may have an alarm unit that notifies the outside when the slippage detection unit detects slippage of the predetermined amount or more.

[0086] According to the above-mentioned configuration, each of the drive units is provided with a notification unit, and each notification unit issues a notification corresponding to the wheel that has slipped. This allows the user to identify the wheel that has slipped, for example, when only some of the wheels are slipping, and to take appropriate measures.

[0087] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0088] 1 stacker crane 10 Traveling cart 11 Mast 12 Lifting section 13 Transfer equipment 21a 1st wheel 21b 2nd wheel 22 Lifting motor 24 First Notification Department 25 Second Notification Department 26 Lift sensor 27a First encoder 27b Second encoder 28a First traction motor 28b Second traction motor 29 Driving sensor 30 Control device 31 Driving control unit 32 Lift control section 33 Transfer control unit 34 First slip detection unit 35 Second slip detection unit 41 First drive unit 42 Second drive unit

Claims

1. a traveling carriage that travels along a track; a mast erected on the traveling carriage; a lifting unit that holds an object to be conveyed and moves up and down along the mast; A control unit; Equipped with the traveling carriage is provided with a plurality of drive units, each drive unit including a wheel that rolls on the track, a motor that drives the wheel, and a slip detection unit that detects slippage of the wheel; The control unit A conveying device characterized in that, when at least the traveling carriage is accelerated, two or more of the plurality of slippage detection units detect the slippage of a predetermined amount or more, the traveling carriage is stopped.

2. The control unit 2. The conveying device according to claim 1, wherein the traveling carriage is stopped when all of the slippage detection units detect a slippage of a predetermined amount or more at least while the traveling carriage is being accelerated.

3. a position detection unit that detects a position of the traveling carriage along the track, 3. The conveying device according to claim 1, wherein the slippage detection unit detects the slippage based on the number of rotations of the motor and the amount of change in the position detected by the position detection unit.

4. The conveying device described in claim 3, characterized in that the slippage detection unit performs a threshold judgment to determine whether the difference between the travel distance of the traveling carriage calculated based on the rotation speed of the motor and the amount of change in the position detected by the position detection unit is greater than or equal to a predetermined threshold, and determines that the slippage of greater than or equal to the predetermined amount has occurred if the difference is greater than or equal to the threshold.

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