CN110316499B

CN110316499B - Article conveying device

Info

Publication number: CN110316499B
Application number: CN201910211128.5A
Authority: CN
Inventors: 田中繁行; 田中淳
Original assignee: Daifuku Co Ltd
Current assignee: Daifuku Co Ltd
Priority date: 2018-03-29
Filing date: 2019-03-20
Publication date: 2022-02-08
Anticipated expiration: 2039-03-20
Also published as: KR20190114776A; TW201945263A; CN110316499A; TWI782198B; JP2019172439A; JP6870643B2

Abstract

The invention provides an article conveying device, wherein an article support body for supporting an article protrudes towards the left and right direction from a lifting platform which lifts along the vertical direction, and the article conveying device properly controls the actions of the lifting platform and the article support body. Among the plurality of elevation drive devices that control the elevation operation of the elevation table, the elevation drive device positioned on the side of the projecting direction operates in the position control mode, and the elevation drive device positioned on the opposite side operates in the torque control mode.

Description

Article conveying device

Technical Field

The present invention relates to an article transport apparatus for transporting an article in a facility, and more particularly to an article transport apparatus including a lift base that is raised and lowered by a lift column extending in a vertical direction.

Background

In facilities such as automated storage facilities that manage a plurality of articles, an article transport apparatus for moving the articles in the facilities is used. Patent document 1 describes a stacker crane as an example of a conventional article conveying device. The stacker crane lifts and lowers the lift table along the column. In addition, a articulated fork (SCARA fork) is provided on the lift table.

The stacker crane moves in the front-rear direction in the machine, moves the article in the up-down direction by lifting the lift table in a state where the article is loaded on the articulated fork, and moves the article in the left-right direction by extending and contracting the articulated fork. The stacker crane moves the article forward, backward, upward, downward, and leftward and rightward in this manner. The articulated fork transfers an article between a structure for storing the article, for example, a rack or the like provided in the equipment, and a stacker crane.

Patent document

Patent document 1: japanese patent laid-open publication No. 2006-219233

Disclosure of Invention

If the articulated fork of the stacker crane is extended toward the frame in a state of carrying the article, the front end of the articulated fork is sagged by the weight of the article, and the articulated fork is inclined. In the stacker crane of patent document 1, the height of the lift table is controlled by the inclination angle of the articulated fork, and the height of the base of the stacker crane is adjusted to prevent the inclination.

However, even if the inclination angle of the articulated fork is constant, the amount of sagging of the front end of the articulated fork may be different due to the extension of the articulated fork to the right or to the left. Fig. 6 and 7 show a case where the conventional stacker crane 70 transfers the article 50 to a storage rack (rack). In fig. 6, the article 50 is moved to the left article storage rack 80L in the figure, and in fig. 7, the article 50 is moved to the right article storage rack 80R in the figure.

As shown in fig. 6 and 7, the stacker crane 70 includes a plurality of

columns

72L and 72R arranged in parallel on the left and right, and the lift table 74 is raised and lowered by both a left lifter 76L that raises and lowers the lift table 74 along the left column 72L and a right lifter 76R that raises and lowers the lift table 74 along the right column 72R. When a plurality of lifters raise and lower 1 of the lifter tables 74 as described above, each lifter shares tasks such that one lifter controls the vertical position and the other lifter controls the lifting torque, and each lifter can smoothly raise and lower without losing the balance between the left and right. Here, the left lifter 76L controls the vertical position, and the right lifter 76R controls the lifting torque.

When the vertical lift 74 reaches the target height 70H, the left lifter 76L that controls the vertical position (height) operates to maintain the left side of the vertical lift 74 at the target height 70H. If the articulated fork 78 on the lift table 74 is extended to the left side in this state as shown in fig. 6, the height of the left side of the lift table 74 is maintained at the target height 70H, but the tip of the articulated fork 78 hangs down by the weight of the article 50 and is slightly lower than the expected height 78H (the upper position higher than the target height 70H by the thickness of the articulated fork 78).

In contrast, when the articulated fork 78 extends to the right as shown in fig. 7, the base of the articulated fork 78 is positioned on the right side of the elevating table 74, and the distance between the position where the left lifter 76L maintains the height (the left side of the elevating table 74) and the front end of the articulated fork 78 becomes large. Thus, even if the height of the left side of the elevating platform 74 is maintained at the target height 70H, the difference between the height of the front end of the articulated fork 78 and the expected height 78H becomes larger than when the articulated fork 78 is extended toward the left side. As shown in fig. 6 and 7, even when the inclination angle α of the articulated fork 78 is the same between the case where the articulated fork 78 is extended to the left side and the case where the articulated fork 78 is extended to the right side, the height of the front end of the articulated fork 78 is low in the case where the articulated fork is extended to the right side.

Therefore, when the articulated fork 78 extends to the right, if the lifter or the like adjusts the height of the base of the articulated fork 78 only in accordance with the inclination angle α, the tip of the articulated fork 78 cannot be prevented from drooping sufficiently. Further, since the (absolute) height of the front end of the articulated fork 78 is lower than the expected height 78H, even if the relative height between the base and the front end of the articulated fork 78 is adjusted by a lifter or the like, the sagging cannot be sufficiently prevented. As a result, as shown in fig. 7, when the articulated fork 78 extends to the right (opposite side to the lifter that controls the vertical position), the height of the front end of the articulated fork 78 becomes too low, and the front end of the articulated fork 78 enters the height region of the shelf of the storage rack 80. In this case, the articulated fork 78 or the article 50 interferes with the shelf, or the lifter or the like does not move the articulated fork 78 in the vertical direction by an accurate amount when the article 50 is transferred to the shelf, and the article transport apparatus may not normally transfer the article 50.

Therefore, an object of the present invention is to prevent the front end of the articulated fork from excessively drooping even when the articulated fork (article support) is extended (projected) to the left or extended to the right, and to prevent a problem that the article transport device cannot normally transfer an article due to the articulated fork intruding into a height region of a shelf of a storage rack.

In order to solve the above problem, an example of an article transport device according to the present invention includes: a lifting table which is lifted along the vertical direction; and an article support that can support an article and can protrude from the lift table in a left-right direction intersecting the vertical direction, wherein the lift table is guided by a plurality of lift columns extending in the vertical direction, and the lift operation of the lift table is controlled by a lift drive device provided to each of the lift columns, the lift drive device is operable in any one of a position control mode in which a vertical position of the lift table is controlled and a torque control mode in which a lift torque for raising and lowering the lift table in the vertical direction is controlled, and the lift drive device that operates in the position control mode operates to maintain the vertical position of the lift table when the lift table stops being raised and lowered in the vertical direction, when the article support protrudes toward one side in the left-right direction, the lifting drive device provided to the lifting column located on the one side operates in the position control mode, and the lifting drive device provided to the lifting column located on the other side operates in the torque control mode.

Preferably, the lifting columns are disposed at four corners of a quadrangle in a plan view and provided with 4, the lifting table is provided with a transfer operation control device capable of controlling an operation of moving the article support body to the left or right side along the left-right direction, and the transfer operation control device is capable of executing: the article support device is configured to be capable of being lifted by the lifting table in a manner that the article support device is protruded from the inner side of the 4 lifting columns to the outer side and is protruded to either the left side or the right side, and the article support device is configured to be pulled up from the outer side of the 4 lifting columns to the inner side.

More preferably, the transfer operation control device performs the protrusion operation after performing the lifting operation of the lifting table, performs the pull-up operation before performing the lifting operation of the lifting table, determines, before starting the lifting operation of the lifting table, which direction the transfer operation control device is to protrude the article support body toward either the left side or the right side after the lifting operation, and when starting the lifting operation of the lifting table, the lifting drive devices provided to the 2 lifting columns located on the side where the transfer operation control device is to protrude the article support body are all operated in the position control mode, and the lifting drive devices provided to the 2 lifting columns located on the other side are all operated in the torque control mode.

In addition, the 4 lifting columns may be provided with lifting marks indicating positions in the vertical direction, and the lifting drive device operated in the position control mode may be operated to raise and lower the lifting table to a position of the lifting mark corresponding to a target position in the vertical direction.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the article transport device of the present invention, since the elevation drive device located on the side of the direction in which the article support protrudes operates in the position control mode, the distance between the portion held at a constant vertical position by the elevation drive device in the position control mode and the tip of the article support does not become large, and therefore, the tip of the article support does not sag greatly, and excessive inclination of the article support can be prevented.

Drawings

Fig. 1 is a plan view of a stacker crane according to an embodiment of the present invention.

Fig. 2 is a rear view showing the stacker crane of the present embodiment.

Fig. 3 is a flowchart showing an operation procedure of the stacker crane according to the present embodiment.

Fig. 4 is a rear view showing a state where the stacker crane according to the present embodiment transfers an article to the left storage rack.

Fig. 5 is a rear view showing a state where the stacker crane according to the present embodiment transfers an article to the right storage rack.

Fig. 6 is a rear view showing a state in which the conventional stacker crane transfers an article to the left storage rack.

Fig. 7 is a rear view showing a state where the conventional stacker crane transfers an article to the right storage rack.

Description of the symbols:

10 … stacker crane, 11 … transport control device, 12 … upright post, 14 … lifting driving device, 16 … lifting mark, 20 … lifting platform, 24 … transfer motion control device, 30 … articulated fork, 40 … storage rack, 50 … article, 70 … stacker crane, 78 … articulated fork, 80L, 80R … storage rack and alpha … inclination angle.

Detailed Description

Fig. 1 and 2 show a plan view and a rear view of a stacker crane 10 as an article carrying device according to an embodiment of the present invention. The stacker crane 10 moves along a moving rail 18, and the moving rail 18 is provided along a conveyance path set in advance in the facility. Fig. 2 is a rear view of the stacker crane 10 viewed from the rear side in the moving direction. The stacker crane 10 is provided with a conveyance control device 11, and the conveyance control device 11 comprehensively manages all operations of the stacker crane 10, such as movement along the movement rail 18, a lifting operation by a lifting drive device 14 described later, and a projecting and retracting operation by a transfer operation control device 24 described later.

The stacker crane 10 includes a plurality of columns 12 (lifting columns) extending in the vertical direction. As shown in fig. 1, each corner of the quadrangle in plan view has 1 column and 4 columns 12 in total. The scale (the elevation mark 16) indicating the position in the vertical direction of the column 12 may be disposed by a method of providing scales or numerical value display at a constant interval along the column 12, or embedding a magnet. Hereinafter, the 2 columns on the left side in the left-right direction are sometimes referred to as left columns 12La, 12Lb, and the 2 columns on the right side are sometimes referred to as right columns 12Ra, 12 Rb.

The stacker crane 10 is provided with: an elevating platform 20 which is guided by the column 12 and ascends and descends in the vertical direction; and a joint type fork 30 (article support) which can protrude (extend and retract) in the left-right direction from the elevating table 20. The articulated fork 30 can support the article 50, and the article 50 can be transferred between the storage rack 40 provided on the left and right sides of the stacker crane 10 and the stacker crane 10 by the articulated fork 30 protruding in the left-right direction.

Each of the columns 12 is provided with a vertical movement driving device 14 for vertically moving the vertical movement table 20. As a specific configuration example of the elevation drive device 14, a sprocket (not shown) is attached to each column 12, and the elevation base 20 is elevated by a chain (not shown) wound around the sprocket. That is, the chain connected to the elevating table 20 is wound or fed by rotating the above-described sprocket by a motor or the like which is electronically controlled, and the elevating table 20 can be elevated. In this embodiment, the height, the moving speed, and the lifting torque of the lifting table 20 can be controlled by controlling the winding amount, the winding speed, and the winding torque of the chain by electronic control.

Hereinafter, the vertical movement driving devices provided on the left columns 12La and 12Lb may be referred to as left vertical movement driving devices 14La and 14Lb, respectively, and the vertical movement driving devices provided on the right columns 12Ra and 12Rb may be referred to as right vertical movement driving devices 14Ra and 14Rb, respectively.

The elevation driving device 14 can check the height (vertical position) of the elevation base 20 at present by referring to the elevation marks 16 provided along the column 12. As a method of referring to the elevation mark 16, a scale provided on the column 12 may be detected by an optical detection means such as a camera or a numerical display, or a magnet embedded in the column 12 may be detected by a magnetic sensor. When the elevation driving device 14 detects the scale and the magnet, the current height may be calculated by counting the number of times of detection since the state where the elevating table 20 is located at the lowest stage, or the shape of the scale and the correspondence between the magnetic pattern of the magnet and the height may be determined in advance, and the current height may be determined based on the correspondence.

The lift table 20 is provided with a transfer operation control device 24 that controls the operation of the articulated fork 30 described above. The transfer operation control device 24 can perform a projecting operation for projecting the articulated fork 30 from the inside of the 4 columns 12 to the outside and a drawing operation for drawing the articulated fork 30 from the outside to the inside, and can change the direction of projecting and drawing the articulated fork to the left or right side. The transfer operation control device 24 is operable in conjunction with the operating state of each of the elevation drive devices 14, and performs the projecting operation and the retracting operation of the articulated fork 30 when the elevation table 20 is at an appropriate height.

The elevation drive device 14 can be operated in any one of 2 modes, i.e., a position control mode and a torque control mode. The position control mode is a mode for moving the elevating platform 20 to a target position, and the elevating drive device 14 in this mode elevates the elevating platform 20 to a height (to find the target elevating marker 16) indicated (set) from the outside while referring to the elevating marker 16 provided on the column 12. For example, when the elevation drive device 14 is configured to include the aforementioned sprocket, chain, and motor and the motor is a pulse motor, the elevation table 20 can be moved to the target height by operating the pulse motor by the number of pulses required to reach the target height. When the elevation table 20 reaches the target height, the elevation drive device 14 in the position control mode stops the elevation of the elevation table 20 and operates to maintain the height of the elevation table 20 at the position.

The torque control mode is a mode for controlling the lifting torque for lifting the lifting table 20, and the lifting drive device 14 operating in this mode operates basically following the operation of the lifting drive device 14 operating in the position control mode described above. That is, the elevation drive device 14 in the torque control mode does not function by itself, and when a plurality of (4 in this case) elevation drive devices 14 are associated with 1 elevation stage 20 as shown in fig. 1, some of them (2 on the left and right sides in this case) operate in the position control mode, and the others operate in the torque control mode. The elevation driving device in the torque control mode operates in accordance with the movement speed and the elevation torque when the elevation driving device 14 in the position control mode intends to move the elevation base 20 toward the target height, so as to obtain the movement speed and the elevation torque equivalent thereto.

In the stacker crane 10 according to the present embodiment, which of the lifting/lowering drive devices 14 is the position control mode and which of the lifting/lowering drive devices 14 is the torque control mode are changed depending on which of the left and right sides the articulated fork 30 protrudes. The operation of the stacker crane 10 will be described below with reference to the flowchart of fig. 3, and fig. 4 and 5.

As an example, a case where the stacker crane 10 transfers the article 50 that has been placed on the articulated fork 30 toward the vacant position of the storage shelf 40 will be described. First, a "transfer target position" indicating a position (front-rear, up-down, and left-right direction positions) of the storage rack 40 to which the article 50 should be transferred (placed), that is, a position (front-rear, up-down, and left-right direction positions) in the storage rack 40 is transmitted from the outside (a person or a system such as an equipment manager or an operator who has an authority to determine the processing of the article 50) to the conveyance controller 11 of the stacker crane 10, and the conveyance controller 11 receives the transfer target position (step S01 in fig. 3).

The conveyance control device 11 that has received the "transfer target position" determines which of the left and right sides the articulated fork 30 is to be finally projected, moves the stacker crane 10 to the front-rear direction position corresponding to the "transfer target position", and transfers the article 50 to the "transfer target position" (step S02 in fig. 3).

When it is determined which of the left and right sides the articulated fork 30 is to be projected, the elevation drive device 14 located on the side of the direction in which it is intended to be projected is determined as the person in charge of the "position control mode" (step S03). That is, if the predetermined articulated fork 30 protrudes to the left, the left elevation drive devices 14La and 14Lb are position control mode actors, and if the predetermined articulated fork 30 protrudes to the right, the right elevation drive devices 14Ra and 14Rb are position control mode actors. The elevation drive device 14 located on the opposite side of the direction in which the projection is planned is assumed to be in the role of the "torque control mode".

When the clerk in the "position control mode" is determined and the stacker crane 10 has moved to the target front-rear direction position, the lifting operation of the lifting platform 20 is started (step S04). At this time, as previously determined, the elevation drive device 14 located on the side of the predetermined articulated fork 30 in the projecting direction is operated in the "position control mode", and the elevation drive device 14 located on the opposite side thereof is operated in the "torque control mode". The elevation driving device 14 operating in the "position control mode" refers to the elevation mark 16 provided on the column 12 to check the height (vertical position) of the elevation base 20 to which the elevation base is currently located. When the lifting platform 20 moves to a height corresponding to the "transfer target position", the lifting operation is completed, and the lifting drive device 14 operating in the "position control mode" operates to maintain the height of the lifting platform 20 at the position.

When the elevating operation of the elevating platform 20 is completed, the transfer operation control device 24 starts the projecting operation of projecting the articulated fork 30 (step S05). During the projecting operation, the up-down driving device 14 continues the "position control mode" and the "torque control mode" that it is in. That is, the elevation drive device 14 on the side close to the direction in which the articulated fork 30 protrudes operates in the "position control mode" so as to maintain the height of the elevation table 20 at the current position.

When the protrusion operation of the articulated fork 30 is completed and the article 50 on the articulated fork 30 is transferred to the "transfer target position" in the storage rack 40, the drawing operation of drawing the articulated fork 30 is started (step S06). When the drawing operation is completed, the operation of transferring the article 50 to the "transfer target position" is completed.

In practice, the operation for delivering the article 50 on the articulated fork 30 to the storage rack 40 may be performed between the projecting operation (step S05) and the drawing operation (step S06). For example, if the front-rear width of the articulated fork 30 is designed to be smaller than the gap between the shelves of the storage rack 40 and the front-rear width of the article 50 is larger than the gap between the shelves, it is possible to leave only the article 50 on the shelves by slightly lowering the articulated fork 30 by the elevation driving device 14 and passing through the gap between the shelves of the storage rack 40 from the top down.

When the operation of transferring the article 50 to the "transfer target position" is completed as described above, the transport controller 11 of the stacker crane 10 receives the next "transfer target position" from the outside (return to step S01). However, the next "transfer target position" is not a position within the storage shelf 40 where the article 50 is to be placed, but a position within the storage shelf 40 where the article 50 is to be taken out.

Although the above description has been made of the case where the stacker crane 10 transfers ("sets") the article 50 already placed on the articulated fork 30 to the vacant position of the storage rack 40, the transport control device 11 receives the position of the article 50 in the storage rack 40 from the outside as the "transfer target position" and performs the processing in the same manner as the above-described operation procedure when the stacker crane 10 transfers ("takes out") the article 50 stored in the storage rack 40 to the articulated fork 30. Further, between the protrusion operation (step S05) and the drawing operation (step S06), the article 50 can be moved from above the shelf to the articulated fork 30 by, for example, slightly raising the articulated fork 30 by the elevation drive device 14 and passing through the gap of the shelf of the storage rack 40 from below to above.

According to the stacker crane 10 of the present embodiment, the elevation drive device 14 on the side close to the projecting direction of the articulated fork 30 in the projecting operation (step S05) operates in the "position control mode", and therefore, the tip end of the articulated fork 30 does not largely droop.

Specifically, fig. 4 shows a case where the articulated fork 30 protrudes to the left (the stacker crane 10 transfers the article 50 to the left storage rack 40). In this case, since the left elevation drive devices 14La and 14Lb are in the "position control mode", the left side of the elevation table 20 is maintained at the height of the elevation flag 16 corresponding to the "transfer target position". Since the distance between the portion maintaining the height and the front end of the articulated fork 30 is not so large, the front end of the articulated fork 30 does not largely droop.

Next, fig. 5 shows a case where the articulated fork 30 protrudes toward the right (the stacker crane 10 transfers the article 50 toward the storage rack 40 on the right). In this case, since the right elevation drive devices 14Ra and 14Rb are in the "position control mode", the right side of the elevation table 20 is maintained at the height of the elevation mark 16 corresponding to the "transfer target position". Since the distance between the portion maintaining the height and the front end of the articulated fork 30 is not so large, the front end of the articulated fork 30 does not largely droop.

As can be seen by comparing fig. 4 and 5, in the present embodiment, the amount of sagging of the front end of the articulated fork 30 is not different between the case where the direction in which the articulated fork 30 protrudes is the left side and the case where the direction in which the articulated fork 30 protrudes is the right side. In both cases, the front ends of the articulated forks 30 do not hang down significantly, and therefore, it is possible to prevent a problem that the hanging articulated forks 30 enter the height area of the shelf of the storage rack 40 and the articles 50 cannot be transferred normally.

For convenience of description, the stacker crane 10 performs the lifting operation after the movement in the front-rear direction is completed, and performs the protrusion operation after the lifting operation is completed, but the operation of the next stage may be started before the operation of the previous stage is completed. That is, the up-and-down operation may be started during the movement in the front-and-rear direction, and the protrusion operation may be started during the up-and-down operation. In this case, since the operation of the previous stage does not need to be continued until the end, the time required for transferring the article 50 is shorter.

In addition, although the stacker crane 10 provided with 4 columns 12 has been described above, the number of columns is not limited to this, and may be, for example, one on the left side and one on the right side, 2 in total, or more than 4. Regardless of the number of columns, when the articulated fork 30 is projected, the elevation drive device 14 located in the direction of the projection may be operated in the position control mode.

In addition, in order to simplify the control, the step of determining the operation mode of the elevation drive device 14 according to the direction in which the articulated fork 30 is projected before the start of elevation (step S03 in fig. 3) may be omitted. That is, for example, it may be determined that the left elevation drive devices 14La and 14Lb select the position control mode and the right elevation drive devices 14Ra and 14Rb select the torque control mode during the elevation (step S04), and after the elevation table 20 reaches the target height and the elevation is stopped, only during the projecting operation and the retracting operation of the articulated fork 30 (during the periods of step S05 and step S06), which one of the left elevation drive devices 14La and 14Lb and the right elevation drive devices 14Ra and 14Rb selects the position control mode may be newly determined according to the projecting and retracting directions.

The elevation mark 16 provided on the column 12 is not necessarily required, and the elevation mark 16 may not be provided if the vertical position of the elevating platform 20 is estimated by another method. For example, in the case where the lifting drive device 14 includes a sprocket, a chain, and a motor, if the conveyance control device 11 or the like checks the operation history of the lifting drive device 14 to find how much the motor winds and feeds the chain from the initial state, the movement amount of the lifting table 20 can be calculated.

Claims

1. An article conveying device, comprising: a lifting table which is lifted along the vertical direction; and an article support body capable of supporting an article and capable of protruding from the lifting table in a left-right direction intersecting the up-down direction,

the article carrying device is characterized in that,

the lifting table is guided by a plurality of lifting columns extending in the vertical direction, and the lifting action of the lifting table is controlled by a lifting driving device arranged on each lifting column,

the lifting drive device can be operated in any one of a position control mode for controlling the position of the lifting table in the vertical direction and a torque control mode for controlling the lifting torque for lifting the lifting table in the vertical direction,

the elevation driving device operating in the position control mode operates to maintain the vertical position of the elevation table when the elevation table stops moving up and down in the vertical direction,

when the article support protrudes toward one side in the left-right direction, the lifting drive device provided to the lifting column located on the one side operates in the position control mode, and the lifting drive device provided to the lifting column located on the other side operates in the torque control mode.

2. The article carrying device according to claim 1,

the lifting upright columns are provided with 4 pieces of lifting upright columns which are arranged at the corners of a quadrangle in a plan view,

a transfer operation control device capable of controlling an operation of moving the article support in the left-right direction to the left or right is provided on the lifting table,

the transfer operation control means can execute: a projecting operation of projecting the article support body from the inner side of the 4 lifting columns to the outer side and projecting the article support body in either of the left side or the right side, and a drawing operation of drawing the article support body from the outer side of the 4 lifting columns to the inner side,

when the elevating table is moved up and down, the elevating drive devices provided to the 2 elevating columns located on the left side are all operated in the same control mode, and the elevating drive devices provided to the 2 elevating columns located on the right side are all operated in a control mode different from that of the elevating drive device located on the left side.

3. The article carrying device according to claim 2,

the transfer operation control device performs the protrusion operation after the lifting operation of the lifting table is performed, and performs the pull-up operation before the lifting operation of the lifting table is performed,

determining, before starting the elevating operation of the elevating table, which direction the article support body is projected toward either the left side or the right side by the transfer operation control device after the elevating operation,

when starting the lifting operation of the lifting table, the lifting drive devices provided to the 2 lifting columns located on the side where the transfer operation control device is scheduled to project the article support body are all operated in the position control mode, and the lifting drive devices provided to the 2 lifting columns located on the other side are all operated in the torque control mode.

4. The article carrying device according to claim 2 or 3,

the 4 lifting upright columns are respectively provided with a lifting mark for showing the position in the vertical direction,

the elevation driving means operated in the position control mode operates to elevate the elevation base to a position of the elevation flag corresponding to a position in the vertical direction set as a target.