Abstract:
A multi-tier automated warehouse includes first and second stacking racks having multiple tiers of shelves and being positioned facing one another in parallel; loading shuttles which are capable of horizontal travel between the stacking racks, and which carry out loading and unloading of cargo upon the shelves; and an elevator device for moving the loading shuttles to different tiers. The elevator device further includes masts which are positioned adjacent to the stacking racks; a shuttle elevator platform, which is positioned elevatably on the inner side of the masts, for elevating the loading shuttles; and cargo elevator platforms, which are positioned elevatably on the outer side of the masts, for elevating the cargo. In a state where the shuttle elevator platform is aligned with the cargo elevator platforms, it is possible for the loading shuttles on the shuttle elevator platforms to carry out cargo loading and unloading to the cargo elevator platforms, allowing handling cargo even while the loading shuttles are being elevated, obviating the need for wasteful waiting for cargo. As a result, it is possible to implement high performance.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims the priority benefits of International Patent Application No. PCT/JP2011/072277, filed on Sep. 28, 2011, which is hereby incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a highly-functional and flexible automated storage/retrieval system that includes at least one pair of multi-tier racks arranged parallel to each other and a transferring shuttle running horizontally between these multi-tier racks to store a load to or retrieve a load from the multi-tier racks. 
     BACKGROUND ART 
     As the above type of automated storage/retrieval system, for example, the automated storage/retrieval system described in Japanese Patent Application Publication No. JPH08-324721 is well-known. The automated storage/retrieval system described in JPH08-324721 includes at least one pair of left and right multi-tier racks, each being composed of multi-tier shelves. Between these multi-tier racks are provided a transferring shuttle that can run in a horizontal direction. The transferring shuttle is for storing a load to or retrieving a load from the left or right multi-tier racks. 
     The automated storage/retrieval system described in such Japanese patent application publication is referred to as a captive-type automated storage/retrieval system since one transferring shuttle is exclusively provided for each tier of the multi-tier racks. This captive-type automated storage/retrieval system is highly efficient, but the increase of the number of tiers of the multi-tier racks increases the number of expensive transferring shuttles and the number of waiting transfer shuttles thereof, which in turn increases the whole cost of the automated storage/retrieval system. 
     Then, conventionally, as described in Japanese Patent Application Publication No. 11-278607, an automated storage/retrieval system is known in which an elevator to move a transferring shuttle upward and downward is disposed adjacent to a multi-tier rack. That is, by using the elevator to move the transferring shuttle to another tier, the number of transferring shuttles can be made to be less than the number of tiers of the multi-tier racks. Such an automated storage/retrieval system is referred to as a roaming-type automated storage/retrieval system since the transferring shuttle can move to any tier of the multi-tier racks. 
     SUMMARY OF THE INVENTION 
     In the above conventional roaming-type automated storage/retrieval system, reduction of the number of transferring shuttles can reduce the whole cost of the system, but there is the problem that lifting movement of the transferring shuttle takes time, thereby limiting the throughput performance of the system. 
     Accordingly, the present invention provides a roaming-type automated storage/retrieval system that has an advantage of lower cost and a high throughput performance. 
     An automated storage/retrieval system according to a first aspect of the present invention includes a first multi-tier rack and a second multi-tier rack arranged parallel to each other, each having shelves; a transferring shuttle that can run in a horizontal direction along a shelf of a selected tier between the first and second multi-tier racks to store a load onto and retrieve a load from the shelf; and an elevator for moving a transferring shuttle to another tier, wherein the elevator includes a shuttle elevating platform for lifting movement with a transferring shuttle placed thereon, the shuttle elevating platform being able to move upward and downward adjacent to the first and second multi-tier racks, and a first load elevating platform and a second load elevating platform for lifting movement with a load placed thereon, respectively. The first and second load elevating platforms are able to move upward and downward together with the shuttle elevating platform while being horizontally in alignment with the shuttle elevating platform. When the shuttle elevating platform is in alignment with the first load elevating platform, a transferring shuttle on the shuttle elevating platform can deliver a load to or receive a load from the first load elevating platform, and when the shuttle elevating platform is in alignment with the second load elevating platform, a transferring shuttle on the shuttle elevating platform can deliver a load to or receive a load from the second load elevating platform. 
     In such a configuration, the shuttle elevating platform and the first load elevating platform and/or second load elevating platform can move upward and downward in alignment with each other, and during the lifting movement, a load can be delivered between the load elevating platform and the shuttle elevating platform. Accordingly, during the lifting movement of the transferring shuttle, it is not necessary to have a load wait on the transferring shuttle, thus contributing to improvement of the throughput performance of the automated storage/retrieval system. 
     The first load elevating platform and second load elevating platform may be fixed to the shuttle elevating platform in alignment with each other to move upward and downward together with the shuttle elevating platform, or the shuttle elevating platform, first load elevating platform and second load elevating platform may move upward and downward independently from one another. 
     The load elevating platform may include a conveyor that can convey a load thereon. This enables the load elevating platform to deliver a load to or receive a load from a storage conveyor and a retrieval conveyor of a conveying system outside the automated storage/retrieval system. 
     If higher throughput performance is needed, a waiting platform to place a load for waiting may be disposed on at least part of the tiers of the first multi-tier rack and second multi-tier rack, allowing for delivery of the load between this waiting platform and the first load elevating platform and second load elevating platform. In the area where the waiting platform is disposed, only loads can be delivered on the tiers with the waiting platform, as with a captive-type automated storage/retrieval system, further improving the throughput performance of the system. 
     The waiting platform may include a conveyor that can convey a load thereon in order to smoothly deliver a load to or receive a load from the load elevating platforms. 
     Instead of providing a conveyor on the waiting platform, the load elevating platform may include a handling mechanism that pushes a load onto the waiting platform or pulls a load from the waiting platform. 
     Each of the shelves may include a frame to fix auxiliary equipment, and the waiting platform may be fixed to this frame. This allows for easy change from the roaming-type to the captive-type or easy change from the roaming-type to a hybrid-type of the roaming-type and captive-type. 
     In the automated storage/retrieval system according to the present invention as described above, the shuttle elevating platform and load elevating platform can move upward and downward in alignment with each other. Accordingly, by performing handover of a load between the load elevating platform and the shuttle elevating platform while a transferring shuttle is moving upward and downward, the transferring shuttle does not need to have a load wait thereon. This can improve the throughput performance of the automated storage/retrieval system even if the system is the roaming-type. In addition, the automated storage/retrieval system according to the present invention can reduce an occupied time of the transferring shuttle on operation, which can reduce the number of transferring shuttles, exhibiting the roaming-type&#39;s inherent effect, that is, an advantageous effect in cost. 
     These and other objects, advantages and features of this invention will become apparent upon review of the following specification in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic top plan view illustrating an automated storage/retrieval system according to a first embodiment of the present invention; 
         FIG. 2  is a schematic side elevation view of the automated storage/retrieval system in  FIG. 1 ; 
         FIG. 3  is a schematic top plan view illustrating an automated storage/retrieval system according to a second embodiment of the present invention; 
         FIG. 4  is a schematic side elevation view of the automated storage/retrieval system in  FIG. 3 ; 
         FIG. 5  is a schematic top plan view of an automated storage/retrieval system according to a third embodiment of the present invention; and 
         FIG. 6  is a schematic side elevation view of the automated storage/retrieval system in  FIG. 5 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Now, preferred embodiments of the present invention will be described with reference to the drawings. In the drawings, identical or corresponding parts have the same reference numbers. 
       FIG. 1  is a schematic plane view illustrating an automated storage/retrieval system  100 . This automated storage/retrieval system  100  is the roaming-type and includes an elevator  12  for moving the transferring shuttle  10  upward and downward. 
     Specifically, this automated storage/retrieval system  100  includes at least one pair of left and right pair multi-tier racks  14 L,  14 R, as illustrated. Each of the multi-tier racks  14 L,  14 R has shelves  16  extending in the same horizontal direction (front-back direction in  FIG. 1 ). The pair of multi-tier racks  14 L,  14 R are arranged parallel to each other in a predetermined space apart from each other. The left multi-tier rack  14 L corresponds to the first multi-tier rack in the claims, and the right multi-tier rack  14 R corresponds to the second multi-tier rack in the claims. 
     Between these multi-tier racks  14 L,  14 R are disposed guide rails (not illustrated), at each tier, parallel to each other in the direction in which the shelves  16  extend; and the transferring shuttles  10  can run along these guide rails. The transferring shuttle  10  is for storing a load P onto and retrieving a load P from the left and right multi-tier racks  14 L,  14 R, and can be a conventional-type transferring shuttle. That is, the transferring shuttle  10  (not specifically illustrated in detail) is composed of a travelling cart  18  that can place a load P on the center portion thereof, and a handling mechanism  20  that is provided in the travelling cart  18  and is for pushing the placed load P rightward or leftward and pulling the load P from outside of the travelling cart  18 . This handling mechanism  20  includes a pair of arms  22  that extend both leftward and rightward in a horizontal direction (left-right direction in  FIG. 1 ) orthogonal to the running direction of the transferring shuttle  10 , and fingers  24  that can open and close which are fixed to each of the arms  22 . By extending the arm  22  either leftward or rightward with the fingers  24  closed, the load P placed on the center portion of the transferring shuttle  10  can be pushed out, enabling the load P to be stored onto a shelf  16  that is on the same height level as that of the surface of the center portion of the travelling cart  18  in the transferring shuttle  10 . By extending the arm  22  onto the shelf  16  with the fingers  24  open, hooking the load P with the fingers  24  and retracting the arm  22  with the fingers  24  closed, the load P can be collected onto the transferring shuttle  10 . 
     Since this automated storage/retrieval system  100  is the roaming-type, a transferring shuttle  10  is disposed at some tiers, but not all tiers, and the number of transferring shuttles  10  is set to be less than the number of tiers of multi-tier racks  14 L,  14 R. A transferring shuttle  10  is moved, between tiers, by the elevator  12  disposed to one end of the left and right multi-tier racks  14 L,  14 R. 
     The elevator  12  is composed of masts  26  disposed at an area adjacent to the space between the left and right multi-tier racks  14 L,  14 R; a shuttle elevating platform  28  that can move upward and downward between these masts  26 ; and a drive motor (not illustrated) for shuttle elevating platform  28 . The shuttle elevating platform  28  includes guide rails that can connect to the guide rail of each tier. Accordingly, by moving the shuttle elevating platform  28  up or down to dispose at a height of a desired tier, the transferring shuttle  10  at the tier can be pulled onto the shuttle elevating platform  28 . Then, by moving the shuttle elevating platform  28  with the transferring shuttle  10  placed thereon to another tier, the transferring shuttle  10  can be put onto a guide rail in the tier. 
     By moving the shuttle elevating platform  28  to the lowest position, the transferring shuttle  10  can be retrieved onto the building floor in which the automated storage/retrieval system  100  is installed. This enables the transferring shuttle  10  to be retrieved from the system without a special crane or the like so that the maintenance work for the shuttle  10  can be performed outside the system. 
     In the automated storage/retrieval system  100  according to the present embodiment, both of the outer left and right sides of the masts  26  of the elevator  12  are further provided with load elevating platforms  30 L,  30 R for moving a load P upward and downward, respectively. In the present embodiment, these load elevating platforms  30 L,  30 R are coupled to the shuttle elevating platform  28  in a horizontal alignment with each other, and travels, that is, moves upward and downward together with the shuttle elevating platform  28 . These load elevating platforms  30 L,  30 R can deliver a load P onto and receive the load P from the transferring shuttle  10  on the shuttle elevating platform  28 . The left load elevating platform  30 L corresponds to a first load elevating platform and the right load elevating platform  30 R corresponds to a second load elevating platform. These load elevating platforms  30 L,  30 R and the shuttle elevating platform  28  may be configured to move upward and downward independently from one another. In such a case, each of the load elevating platforms  30 L,  30 R will have a drive motor. 
     The load elevating platforms  30 L,  30 R, each includes a conveyor  32  so as to convey the load P in a parallel direction with the running direction of the transferring shuttle  10 . Various types can be considered for the type of conveyor  32 , but a roller conveyor is preferable so as to perform delivery of the load P in a direction orthogonal to the conveying direction of the conveyor  32 . 
     As for the conveying direction of the conveyor  32 , that of the left conveyor  32  is a direction that approaches the multi-tier rack  14 L, and that of the right conveyor  32  is a direction that moves away from the multi-tier rack  14 R, in the illustrated embodiment, but it is preferable that these directions can be reversed. 
     Each of the load elevating platforms  30 L,  30 R preferably carries more than one piece of loads P placed thereon and in the illustrated embodiment two pieces of loads P can be placed next to each other along the conveying direction, but each of the load elevating platforms  30 L,  30 R may also be configured to be able to carry only one load P placed thereon. 
     Further, to each of the load elevating platforms  30 L,  30 R can be connected a storage conveyor  34  and a retrieval conveyor  36  extending from the conveying system outside the automated storage/retrieval system  100 . The storage conveyor  34  and retrieval conveyor  36  are disposed at a suitable height level, and in  FIG. 2  both of the storage conveyor  34  and retrieval conveyor  36  are at the same height level as that of the lowest tiers of the multi-tier racks  14 L,  14 R. When the left load elevating platform  30 L is at the same height level as that of the lowest tiers of the multi-tier racks  14 L,  14 R, the exit end of the storage conveyor  34  is aligned with the load elevating platform  30 L, thus enabling the load P from the storage conveyor  34  to be placed onto the load elevating platform  30 L. Similarly, when the right load elevating platform  30 R is at the same height level as that of the lowest tiers of the multi-tier racks  14 L,  14 R, the entrance end of the retrieval conveyor  36  is aligned with the load elevating platform  30 R, thus enabling the load P to be moved from the load elevating platform  30 R to the retrieval conveyor  36 . 
     It should be appreciated that in the automated storage/retrieval system  100  having the above configuration, since the shuttle elevating platform  28  and load elevating platforms  30 L,  30 R operate integrally, the load P on the transferring shuttle  10  can be placed onto the load elevating platform  30 R and the load P on the load elevating platform  30 L can be placed onto the transferring shuttle  10  during the movement of the transferring shuttle  10 . 
     For example, a case where the following three operations are performed will be described: (1) retrieving a load P on the fifth shelves  16  of the multi-tier racks  14 L,  14 R onto the retrieval conveyor  36 , (2) storing a load P from the storage conveyor  34  onto the tenth shelves of the multi-tier racks  14 L,  14 R, and (3) moving a transferring shuttle  10  on the fifth tier to the tenth tier of the multi-tier racks  14 L,  14 R. First, a transferring shuttle  10  on the fifth tier is operated to move in front of the load P to be retrieved, and the load P is retrieved by the handling mechanism  20 . During this time, the shuttle elevating platform  28  of the elevator  12  is moved so that a guide rail of the shuttle elevating platform  28  is in alignment with a guide rail on the fifth tier of the multi-tier racks  14 L,  14 R. After that, the transferring shuttle  10  with the load P placed thereon is moved onto the shuttle elevating platform  28  of the elevator  12 , and then the shuttle elevating platform  28  is moved downward to the same height level as that of the retrieval conveyor  36 . Since the shuttle elevating platform  28  and load elevating platforms  30 L,  30 R are adjacent to each other and moves upward and downward integrally, the load P on the transferring shuttle  10  can be transferred onto the right load elevating platform  30 R by operating the handling mechanism  20  of the transferring shuttle  10  even during descent of the shuttle elevating platform  28 . By this configuration, as soon as the load elevating platform  30 R is aligned with the retrieval conveyor  36 , the load P on the load elevating platform  30 R can be retrieved to the retrieval conveyor  36 . 
     When the right load elevating platform  30 R is in alignment with the retrieval conveyor  36 , the right load elevating platform  30 L is in alignment with the storage conveyor  34 . Accordingly, while the load P is being retrieved, the load P can be transferred from the storage conveyor  34  to the load elevating platform  30 L. When retrieval of the load P and storage of the load P have been completed, the elevator  12  is driven to move the shuttle elevating platform  28  up, having the guide rail of the shuttle elevating platform  28  in alignment with the tenth guide rails of the multi-tier racks  14 L,  14 R. During this movement, the load P on the load elevating platform  30 L can be taken by the handling mechanism  20  onto the transferring shuttle  10 . Accordingly, once the shuttle elevating platform  28  reaches a predetermined height level, the transferring shuttle  10  can immediately move into the multi-tier rack and store the load P at a predetermined position on the shelf  16 . 
     Since the load P can be transferred onto the transferring shuttle  10  during the movement of the transferring shuttle  10  in the above-mentioned way, the three operations can be performed in a series of process without time loss, thus improving the whole throughput capability of the automated storage/retrieval system. 
     The transferring shuttle  10  can move from a predetermined tier to another predetermined tier to directly transfer the load P without returning to storage and retrieval conveyors  34 ,  36 . This operation can reduce the occupied time of the transferring shuttle in storage and retrieval, thus improving the efficiency of the transferring shuttle  10 , which in turn can reduce the number of transferring shuttles. In this case, the load elevating platforms  30 L,  30 R only need to return to the level of the storage and retrieval conveyors  34 ,  36  at every interval of several cycles (=the number of loads that can be placed on the load elevating platforms), and discharge the retrieved load P and receive the load P to be stored. Accordingly, this mode is performed where the elevating platforms have sufficient capability and the transferring shuttle  10  do not have enough capability. In actual operation, these two modes are dynamically combined to realize optimal operation as a whole. 
     It should be easily understood by a person skilled in the art that where the load elevating platforms  30 L,  30 R and shuttle elevating platform  28  can move upward and downward independently as described above, any load can be handled in more various operation modes. 
     Second Embodiment 
     Next, a second embodiment of the present invention will be described. 
       FIG. 3  is a schematic plane view illustrating an automated storage/retrieval system  200  according to the second embodiment, and  FIG. 4  is a schematic side view thereof. This automated storage/retrieval system  200  basically has the same configuration as that of the automated storage/retrieval system  100  according to the first embodiment. Accordingly, parts identical or corresponding to those of the automated storage/retrieval system  100  according to the first embodiment have the same reference numbers, and overlapped description will be omitted. 
     The automated storage/retrieval system  200  according to the second embodiment is different from the automated storage/retrieval system  100  according to the first embodiment in that the automated storage/retrieval system  200  includes waiting platforms  50 L,  50 R to have the load P wait at elevator  12 -side ends of the left and right multi-tier racks  14 L,  14 R. The waiting platforms  50 L,  50 R may be provided at all tiers of the multi-tier racks  14 L,  14 R. Alternatively, as illustrated in  FIG. 4 , the multi-tier racks  14 L,  14 R may be divided into upper and lower parts, the waiting platforms  50 L,  50 R being provided at each tier in the lower part and no waiting platforms  50 L,  50 R being provided in the upper part, or vice versa. In the embodiment illustrated in  FIG. 4 , the upper part will correspond to the roaming-type automated storage/retrieval system according to the first embodiment, and the lower part will correspond to the captive-type automated storage/retrieval system in which a transferring shuttle  10  is provided at each tier. This design is intended to make part of the automated storage/retrieval system the roaming-type and to store slow moving loads to be stored or retrieved in this part, restraining increase of cost, and to make the remaining part thereof almost captive-type or completely captive-type and to store so-called fast moving loads to be stored or retrieved in this remaining part, thus maximizing throughput performance. Accordingly, this design is advantageous for a high-rise automated storage/retrieval system and/or an automated storage/retrieval system that stores loads whose storage and retrieval frequencies are various. 
     Since these waiting platforms  50 L,  50 R according to the second embodiment, each includes a conveyor  52 , the load P can be delivered onto or received from the load elevating platforms  30 L,  30 R of the elevator  12 . More specifically, in the lower part of the automated storage/retrieval system  200 , the conveying direction of the conveyor  52  of the left waiting platform  50 L is backward so that the conveyor  52  can receive the load P from the load elevating platform  30 L to the left of the elevator  12 , and the conveying direction of the conveyor  52  of the right waiting platform  50 R is forward so that the conveyor  52  pushes the load P to the load elevating platform  30 R to the right of the elevator  12 . The waiting platforms  50 L,  50 R on each tier are positioned so as to face the transferring shuttle  10  at the tier, which enables the load P to be transferred between the transferring shuttle  10  and the waiting platforms  50 L,  50 R. Accordingly, in order to smoothly deliver the load P to or receive the load P from the transferring shuttle  10 , the conveyors  52  of the waiting platforms  50 L,  50 R are preferably composed of roller conveyors. 
     In the illustrated second embodiment, each of the waiting platforms  50 L,  50 R is configured to be able to have two pieces of loads P placed thereon, but may also be configured to be able to have one piece of load P or more than two pieces of loads P placed thereon. 
     If the conveyors  32  of the load elevating platforms  30 L,  30 R can be driven in the opposite directions, it is preferable that the conveyors  52  of the waiting platforms  50 L,  50 R can be driven in the opposite directions. 
     In such a configuration, the lower part of the automated storage/retrieval system  200  is operated in the same way as or similar way to a conventional common captive-type automated storage/retrieval system. That is, the load elevating platform  30 L, which is to the right of the elevator  12 , with the load P from the storage conveyor  34  placed thereon moves to the height level of a predetermined right waiting platform  50 R, and transfers the load P onto the waiting platform  50 R. Then, the transferring shuttle  10  at the tier receives the load P from the waiting platform  50 R and stores the load P onto a shelf  16 . Meanwhile, the load P taken out from the shelf  16  waits on a left waiting platform  50 L at the tier, moves to the right load elevating platform  30 R of the elevator  12 , and is transferred to the retrieval conveyor  36 . During this, basically, the shuttle elevating platform  28  of the elevator  12  moves upward and downward empty except when the transferring shuttle  10  is moved. 
     As can be seen from arrows in  FIG. 3 , since a load can be moved rightward and leftward by the transferring shuttle  10 , the load P waiting on the waiting platform  50 L or  50 R at a tier can be moved to the waiting platform  50 L or  50 R at another tier via a transferring shuttle  10  that is moved upward and downward by the elevator  12 . 
     The upper part of the automated storage/retrieval system  200  is operated as with the above first embodiment. 
     The whole of the automated storage/retrieval system  200  may be configured to be the roaming-type and all tiers thereof may be provided with the waiting platforms  50 L,  50 R. In this case, even if the upper part of the automated storage/retrieval system  200  needs to be changed to the captive-type and the lower part needs to be changed to the roaming-type, the need can be dealt with by changing the instructions without a mechanical change, thus advantageously allowing for a dynamic change from the captive-type to the roaming-type or vice versa. 
     Returning to  FIG. 1 , each of portions indicated by a dashed-two dotted line in  FIG. 1  is a frame  40  provided at a shelf  16  at each tier to fix an auxiliary equipment. The frame  40  can be used to increase the area of the shelf  16  by fixing the removable shelf board to the frame  40 . To the frame  40  waiting platform  50 L or  50 R can be fixed but to be removable. This allows for easy design change from the roaming-type in  FIGS. 1 and 2  to the captive-type in  FIGS. 3 and 4 , and also allows for easy design change to the hybrid type of the roaming-type and captive-type. 
     Third Embodiment 
       FIG. 5  and  FIG. 6  are schematic plane and side views illustrating an automated storage/retrieval system  300  according to a third embodiment, respectively. This automated storage/retrieval system  300  is the same as the automated storage/retrieval system  100  according to the first embodiment in basic configuration, and is the same as the automated storage/retrieval system  200  according to the second embodiment in including the waiting platforms  50 L,  50 R. Accordingly, parts identical or corresponding to those of the automated storage/retrieval systems  100  and  200  according to the first and second embodiments have the same reference numbers and overlapped description will be omitted. 
     The automated storage/retrieval system  300  according to the illustrated third embodiment differs from that of the second embodiment in that all tiers of the multi-tier racks  14 L,  14 R are provided with the waiting platforms  50 L,  50 R. The waiting platforms  50 L,  50 R do not have conveyors, the upper surface of each of the waiting platforms  50 L,  50 R is a plane surface and has an area for only one piece of load P. 
     Each of the load elevating platforms  30 L,  30 R of the elevator  12  is composed of a section  32  on which two pieces of loads P can be placed and transferred thereon, and a section  60  that extends from the section  32  to the multi-tier rack  14 L or  14 R. The extended sections  60  are arranged adjacent to the waiting platform  50 L,  50 R at each tier by moving the load elevating platforms  30 L,  30 R upward or downward. Both of the sections  32  and  60  have conveyors and can have three pieces of loads in total placed and transferred thereon. In this Figure, three pieces of loads P in total can be arranged along a transferring direction, but the number of loads that can be placed may be one, two, or more than three. 
     Further, each of the extended sections  60  includes, as a means to transfer a load P to the waiting platforms  50 L,  50 R, a handling mechanism  62  similar to the handling mechanism  20  mounted in a transferring shuttle  10 . That is, the handling mechanism  62  includes a pair of arms  64  that are extendable in the running direction of the transferring shuttle  10  and fingers  66  that can open and close and are fixed to each of the arms  64 . By extending the arm  64  either forward or backward with the fingers  66  closed, the load P placed on the extended section  60  can be pushed out, enabling the load P to be transferred onto the waiting platform  50 L,  50 R or load elevating platform  30 L,  30 R adjacent to the extended section  60 . By extending the arm  64  onto the waiting platforms  50 L,  50 R with the fingers  66  open, hooking a load P with the fingers  66  and retracting the arm  64  with the fingers  66  closed, the load P can be transferred onto the extended section  60  of the load elevating platform  30 L or  30 R. 
     In such a configuration, where the load P is placed on the waiting platform  50 L or  50 R, if the transferring shuttle  10  is disposed at the same tier of the waiting platform  50 L or  50 R and the transferring shuttle  10  does not need to move between tiers (for example, there is no order for another tier, or there is another load that can be retrieved in the same tier), the transferring shuttle  10  can be used to store the load P to the shelf  16  or to collect the load P from the shelf  16 . That is, at all tiers, a captive-type automated storage/retrieval system operation can be performed. 
     The same roaming-type operation as that of the first embodiment can be operated without waiting platforms  50 L,  50 R. In the roaming-type operation, the waiting platforms  50 L,  50 R can be used in order to reduce the time of movement between tiers. In this case, the transferring shuttle  10  never transfers a load or performs only either storage or retrieval on the shuttle elevating platform  28 . 
     In the third embodiment, loads P can be rearranged in the load elevating platforms  30 L,  30 R. That is, by adjusting the method to retrieve the load P between the transferring shuttle  10  on the shuttle elevating platform  28  of the elevator  12 , the sections  32  and  60  of the load elevating platforms  30 L,  30 R, and the waiting platforms  50 L,  50 R, the sequence of loads P arranged on the sections  32  and  60  of the load elevating platforms  30 L,  30 R can be changed from the order of storage and retrieval. This rearrangement of loads P before retrieval leads to easier handling of loads P after retrieval. Since the sequence of storage and retrieval on the load elevating platforms does not necessarily have to correspond to the order of storage and retrieval of transferring shuttles  10 , waiting time of transferring shuttles  10  is reduced, that is, the utilization of transferring shuttles  10  is improved, which in turn improves the throughput performance of the automated storage/retrieval system and reduces the number of transferring shuttles, that is, contributes to cost reduction. 
     In the third embodiment, like the second embodiment, a frame  40  for fixing an auxiliary equipment illustrated in  FIG. 1  can be used to fix the waiting platform  50 R or  50 L to a shelf  16 . This allows for easy design change from the configuration illustrated in  FIGS. 1 and 2  to the configuration illustrated in  FIGS. 5 and 6 . 
     Preferred embodiments of the present invention have been described in detail, but it should be appreciated that the present invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention. For example, in the above embodiments, one storage conveyor and one retrieval conveyor are provided, but storage conveyors and retrieval conveyors arranged one above the other may be provided at each of the right and left tiers, or an independent elevating platform may be configured in two tiers.