FIELD

The invention relates to a shelf system comprising movable shelves and more particularly to a shelf system lift comprising a lift for transporting the movable shelves.

BACKGROUND

Previously known is a palletless storing system of goods, among others from U.S. patent publication. 6129497, where palletless goods crates stacked, one on top of another, are retrieved from the warehouse rack and stacked on the rack. A collecting apparatus is moving on rails in the warehouse, which apparatus is adjusted to take and stack goods crates on different rack levels. On a rack there can be many stacks of crates side by side. The stack retrieved from the rack so that the lifting means of the stacking apparatus catches the bottom-edge of the lower crate in the stack, whereby the whole stack can be lifted on and removed together with the apparatus. The crates are on the rack so that the lifting means can be placed under their edges. This has been resolved so that the crates on the rack are on a smaller base than their bottom part.

With the apparatus it is possible to handle other than crates of a cer- tain size, which are stacked one on top of another, a certain quantity at the most. Anyway, no bearing pallets are needed. Steering of the apparatus takes place from the control centre in the lifting carrier. In the system the content of crates is not identified.

Shelf lifts are capable of moving shelves between their parking posi- tions and an operating station. A shelf may be positioned to be supported in the parking position, when a shelf lift is not transporting the shelf. The Each shelf can store goods that are needed in a specific operating station at a specific time. However, some of the goods on the shelves may be only seldom needed, whereby carrying such goods on the shelves reduces the efficiency of the shelf lift. On the other hand restocking seldom needed goods to the shelves takes place even more seldom than the goods are needed and typically involve manual work. Floor space required by manual restocking may be relatively large particularly in large warehouses, having many rows of shelves. Floor space should be reserved for people and equipment that the people drive such as trolleys or fork lift trucks. BRIEF DESCRIPTION OF SOME EMBODIMENTS

The following is a simplified summary of the invention to provide basic understanding of some aspects of the invention. This summary is not an extensive description of the invention and is not intended to identify the im- portant/critical elements of the invention or to define the scope of the invention. Its only intention is to present some concepts of the invention in a simplified form as an introduction to a more detailed description that follows.

It is an object of the present invention to develop a solution to alleviate the above-mentioned drawbacks. The object of the invention is achieved by an arrangement, a method and a computer program product that are characterised by what is stated in the attached independent claims. Preferred embodiments of the invention are disclosed in the dependent claims.

Some embodiments provide stocking palletless items to a movable shelf and/or collecting palletless items from a movable shelf.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following the invention will be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which

Figure 1 a illustrates an arrangement according to an embodiment; Figure 1 b illustrates an arrangement comprising a warehouse management system according to an embodiment;

Figure 2 illustrates shelf systems in different floors in an arrangement according to an embodiment;

Figures 3a and 3b illustrate controlling arrangements by warehouse management systems according to embodiments;

Figure 4 illustrates controlling an arrangement according to an embodiment;

Figure 5 illustrates guides in a shelf system an embodiment;

Figures 6a and 6b illustrates positions of guides in a shelf system according to an embodiment;

Figures 7a and 7b illustrate partitioners for palletizing palletless variable size items to a movable shelf according to embodiments; and

Figure 8 illustrates a method according to an embodiment. DETAILED DESCRIPTION

Figure 1 a illustrates an arrangement according to an embodiment. Figure 1 a illustrates the arrangement from above. The arrangement may comprise at least one shelf system 102 comprising movable shelves 104a, 140b, 104c, at least one operating station 106 for collecting items from a movable shelf at the operating station and a lift 108 for transporting the movable shelves between parking positions of the shelves in the shelf system and the operating station. This lift may be referred to as a shelf lift. The arrangement further comprises another lift 1 10 for transporting and engaging palletless variable size items. This lift may be referred to as a palletless lift. The palletless lift is capable of docking to the movable shelves 104a, 104b, 104c of the shelf system for communicating items to the shelves or from the shelves.

The items may comprise palletized items and palletless items. The palletized items may refer to items on a movable shelf of the shelf system. The palletless items may refer to variable size items that are transported by the palletless lift to and/or from a movable shelf without a shelf or other structure serving as pallet. The arrangement may store the items in the shelf system and transport the items palletized on the movable shelves to the operating station by the shelf lift. Accordingly, palletless items may be palletized by the pallet- less lift to the movable shelves by the palletless lift transporting palletless items to the movable shelves.

The shelf system may comprise a plurality of shelves, where items may be stored to be collected at the operating station. The shelves may be supported on top of each other and there may be several shelves in parallel. The shelf system may include support structures such as vertical and horizontal beams for supporting the shelves in the shelf system.

The movable shelf may be transferred between its parking position in the shelf system and the operating station by the shelf lift. The parking position may be capable of receiving the movable shelf from the shelf lift and sup- porting the movable shelf in the parking position. In Figure 1 a, the movable shelves are at their parking positions.

The shelf lift 108 may be capable of moving between the parking positions and the movable shelves in the shelf system. The shelf lift may have docking means for attaching to movable shelves. The docking means may be operatively connected to moving means 1 12 of the shelf lift. The moving means may move the docking means for attaching to the movable shelves and transferring the shelves between the parking positions and the operating station. Examples of the moving means comprise a hoisting machinery for vertical movement of the shelf lift, a rail for horizontal movement of the shelf lift in the width direction of the shelves 'w _s ' and a unit for horizontal movement towards a shelf in the depth direction of the shelves 'd _s '.

The palletless lift may comprise a grabber for attaching to palletless items. An example of the grabber is described with Figures 7a and 7b. The palletless lift may be capable of moving between the shelves in the shelf system and an operating station 106. The operating station of the palletless lift may be the same as the operating station of the shelf lift. However, the arrangement may comprise a separate operating station for the palletless lift such that disturbances to the operation of the shelf lift in transporting shelves to the operating station may be avoided. In this way the palletless lift may be capable of stocking palletless items from the operating station to the shelves.

The palletless lift may have docking means for engaging to shelves in the shelf system. The docking means provide that times may be moved from the palletless lift to the shelf and from the shelf to the palletless lift. The palletless lift may comprise moving means 1 14 for moving the palletless lift between the shelves and the operating station. The docking means may be operatively connected to moving means of the palletless lift. Examples of the moving means comprise a hoisting machinery for vertical movement of the palletless lift, a rail for horizontal movement of the palletless lift in the width direction of the shelves 'w _p ' and a unit for horizontal movement towards a shelf in the depth direction of the shelves 'd _p '. An example of the unit for horizontal move- ment is described in more detail with Figures 6a and 6b. It should be appreciated that since the palletless lift transports items that are not palletized, the palletless lift may operate with both fixed shelves and movable shelves in the shelf system. However, it may be preferred to operate the palletless lift with movable shelves for palletizing items on the movable shelves for transportation to the operating station of the movable shelves.

It should be appreciated that the shelves in the shelf system may be movable or fixed. However, in the shelf system at least one of the shelves should be movable for serving the operating station 106 with items palletized on a shelf. It is also possible that all the shelves 104a, 104b, 104c are mova- ble, whereby the movable shelf at the operating may be changed by the shelf lift 108 to another movable shelf from the shelf system. The movable shelves may have the same palletized items, whereby the movable shelf at the operating station may be changed by the shelf lift 108 to another movable shelf in order to remove possible outage of one or more items at the operating station. On the other hand, the movable shelves may have at least partly different pal- letized items, whereby the movable shelves may serve the operating station in different work phases performed at the operating station. Accordingly, the items palletized in the movable shelves may serve different work phases performed at the operating station.

The operating station may have a parking position for a movable shelf such that the movable shelf may be received at the operating station. The operating station allows personnel to collect items from the movable shelf located at the operating station. The arrangement may comprise more than one operating station. At least one operating station may serve collecting items from a movable shelf. At least one operating station may serve feeding pallet- less items for transportation by the palletless lift to the shelf system. Personnel may be present at the operating stations for feeding and collecting the items.

Figure 1 b illustrates an arrangement comprising a Warehouse Management System (WMS) 120 according to an embodiment. The warehouse management system may be connected to units of the arrangement compris- ing a palletless lift 122, a shelf lift 124, operating station 126 and a shelf system 128, examples of which are described above with Figure 1 a. It should be appreciated that there may be more than one, for example two, three, four or any number of units of each kind.

The connection between the WMS and the palletless lift, the shelf lift and the operating station and the shelf system may be provided by a communications bus, for example. However, also dedicated connections may be implemented between the WMS and each unit. The communications bus may be an IP based Ethernet network or an industrial bus. The connection provides transfer of information from the units for maintaining information of items stored in the shelf system in the WMS and for controlling the units. The information of items stored in the shelf system may comprise for each items, information identifying the item and quantity and a location in the shelf system. Additionally, also information of the supplier may be stored each item. Examples of the information of the supplier may comprise name and contact information such as an email address. Information of palletized items stored in the shelf system may be obtained from the movable shelves, the shelf lift and/or from the oper- ating station. Information of palletless items stored in the shelf system may be obtained from the palletless lift or the operating station. The shelf system, operating station, movable shelves, shelf lift and palletless lift may comprise sensors that may detect receiving an item, collecting an item, a position of the pal- letless lift in the shelf system and a position of the shelf lift. Examples of the sensors comprise cameras, weight sensors and optical sensors. The sensors generate information that may be used to determine information of the items stored in the shelf system.

The WMS may maintain a task list that may define items needed at a specific operating station at a given time and/or in a specific work performed by personnel at the operating station. The WMS may control the palletless lift and the shelf lift as needed. The shelf lift may be controlled for transporting items on the movable shelves to and from the operating station or between shelf systems in different floors. The palletless lift may be controlled for trans- porting items to the movable shelves for transportation to the operating station on the movable shelves or to a shelf system in a different floor. It should be appreciated that although only one WMS is illustrated in Figure 1 b further WMSs may be connected with the one or more items described in Figure 1 b, for example using the described connections. Controlling an arrangement by more than one WMS is described in more detail in Figures 3a and 3b.

Figure 2 illustrates shelf systems in different floors in an arrangement according to an embodiment. At least one shelf system 202 may be installed to a higher floor 204 and at least one shelf system 206 may be installed to a lower floor 208. A shelf lift 210 may be installed movable between the shelf system in the lower floor and the higher floor. The shelf systems may be shelf systems in arrangements according to Figure 1 a, where the shelf lift is capable of moving between different floors and between the shelf system and the operating station in each floor. The floors may be connected by a hoistway comprising hoisting means 214, for example hoisting machinery and ropes, for moving the shelf lift between the floors in the hoistway. On the other hand the shelf systems in different floors may be connected by one shelf lift and the arrangements in each floor have a further shelf lift (not shown) for transporting movable shelves between parking positions of the shelves in the shelf system and the operating station.

In an embodiment, the shelf systems in different floors have parking positions for one or more shelves transported by the shelf lift. The shelf lift may transport a movable shelf transported from a parking positon in one floor to a parking position in another floor. The shelf systems in different floors may have more than one parking positions for the shelves transported by the shelf lift such that a plurality of shelves from one floor may be transported to another floor.

In an embodiment, the arrangement comprising shelf systems in different floors may comprise one or more palletless lifts 212 for transporting and engaging palletless variable size items in at least one of the shelf systems or both of the shelf systems. The palletless lift is capable of docking to the mova- ble shelves of the shelf system for communicating palletless items to the movable shelves or from the movable shelves.

Figures 3a and 3b illustrate controlling arrangements by warehouse management systems according to embodiments. The arrangements may comprise one of the arrangements described above. Figure 3a illustrates con- trolling a shelf lift 304 and a palletless lift 306 by a single Warehouse Management System (WMS) 302. Accordingly, the WMS may control both the shelf lift and the palletless lift. Figure 3b illustrates controlling a shelf lift 312 and a palletless lift 314 by a plurality of WMSs 308, 310. Accordingly, the shelf lift may be controlled by one WMS 308 and the palletless lift may be controlled by another WMS 310. In Figure 3b at least one of the WMSs may be capable of operating as master to the other WMS. The WMSs that are not masters may be referred to as slaves. Accordingly, the WMSs may have master-slave relationship, where the slave WMS may operate under control of the master WMS. The master WMS may issue command to the slave WMS. The commands may identify one or more items for transportation to a specific location, for example an operating station, a movable shelf or a partition on the movable shelf.

In Figures 3a and 3b the WMSs are capable of maintaining information of items stored in a shelf system and on determining a need for one or more items in a shelf system or at an operating station. The arrangement may comprise shelf systems in different floors and the WMS may be capable of determining a need for one or more items in one of the floors. The items may be needed in the same floor or in another floor.

In an embodiment, the master-slave relationship between the WMSs may be fixed. Accordingly, one of the WMSs may be set as a master and one of the WMSs may be set as a slave. The master WMS and the slave WMS may be connected such that the master WMS may cause the slave WMS to transport items in the arrangement. The slave WMS and master WMS may be connected by a management interface which allows the master WMS to issue commands for execution by the slave WMS. The slave WMS may provide information of items stored in the shelf system via the management inter- face.

In an embodiment, the master-slave relationship between the WMSs may be negotiated. The WMSs may be connected for negotiating the master-slave relationship, for issuing command from the master WMS to the slave WMS and for exchanging information of items stored in the shelf system. The master WMS and slave WMS may be determined by a protocol of negotiating the master and slave. The protocol may be implemented in both the master and the slave.

In one example of the protocol, a WMS may be set as a master by a request issued by the WMS to one or more other WMSs. The request may be a request to the slave WMSs to transport an item. In this way, the WMS issuing the request may be assumed as master. In another example of the protocol a WMS may request a master token from the slaves. When a WMS accepts the request for the master token, the WMS may send the master token as response, whereby the receiver of the master token may be set as the master and the originator of the master token may be set as a slave.

Figure 4 illustrates controlling an arrangement according to an embodiment. The arrangement may be one of the arrangements described above. The method may start 400, when a palletless lift is operational and capable of transporting and engaging palletless variable size items.

Information of items stored in a shelf system may be maintained

402. The arrangement may comprise a plurality of shelf systems. The shelf systems may be in different floors. The information of the items may be maintained for example by a WMS described with Figure 1 b.

A need for one or more items may be determined 404. The items may be identified by name and location, where the item is needed. The items may be needed in the arrangement, for example at an operating station, a movable shelf, palletless lift and/or a shelf lift. A quantity of needed items may also be determined. The quantity may be expressed by a count of items or by weight for example. In one example, the need may be determined on the basis of a task list of the WMS or a user ordering an item to an operating station. In an embodiment the need may be comprise a need for palletizing one or more items on a movable shelf. In an embodiment the need may be comprise a need for one or more items in a shelf system in a specific floor or at an operating station.

In an embodiment, the need for items palletized on the movable shelf may be determined 404 to meet a demand for items, wherein the needed items comprise frequently needed items and infrequently needed items and the demand for frequently needed items is maintained over a time period during which the demand for infrequently needed items is changed, whereby at least part of the infrequently needed items currently palletized on a movable shelf are changed after the time period has elapsed. In this way the items palletized on the movable shelf may be varied according to the demand. The frequently needed items may be needed constantly, for example daily, whereby the demand for frequently needed items may be relatively constant. The needed items may be defined by a task list maintained by the WMS. The infrequently needed items palletized on the movable shelf may be changed by controlling a palletless lift to transport at least some or all of the infrequently needed items currently palletized on the movable shelf to one or more other shelves in the shelf system and palletizing new infrequently needed items from the shelf system and/or received from an operating station to the movable shelf. The pallet- ized items may additionally comprise frequently needed items to restock the movable shelf. The needed items may be needed by personnel working at the operating station, whereby changing the infrequently items palletized on the movable shelf allow adaptation according to the work phases performed by the personnel. The time period may be for example one day such that the infre- quently needed items may be changed daily, for example at night to prepare the movable shelf for the next work day.

The shelf system may be checked 406 for the presence of the needed items. The presence may be checked from the maintained 402 information. The checking may comprise comparing the needed items determined in 404 to the maintained 402 information. The presence of the needed items may be determined on the basis of information, for example name, identifying the needed items. Additional requirement for the presence may be that the maintained information comprises the needed quantity of the needed items. In an embodiment, the presence of the needed items may be checked in the shelf systems located in different floors. Accordingly, the maintained information may comprise items stored to the shelf systems in different floors and the needed items may be determined present even if they are in a different floor than the location, where the items are needed.

If 408 the needed items are present in the shelf system, the method may proceed to 410. The needed items may be considered present in the shelf system, when the items are stored in the shelf system. The items may be present, when the items are palletized on a movable shelf for example. If the needed items are not present in the shelf system, the method may end 418.

In an embodiment an e-mail order to the supplier for the needed items may be sent, if 408 the needed items are not present. Information of the supplier comprising for example name and contact information such as an email address, may be associated to the information of the item maintained by the WMS.

If 410 the needed items are present in a different floor than the floor, where the items are needed, the method may proceed to transporting 414 the needed items by a shelf lift to the floor, where the items are needed. The transporting may comprise palletizing 412 the needed items from the shelf system to a movable shelf of a shelf lift and transporting 414 the needed items by the shelf lift to the floor, where the items are needed. The needed items may be palletized on the movable shelf by a palletless lift. It should be appreciated that the items may be palletized on the movable shelf before the need for items has occurred, whereby it may be sufficient to determine that the items are on the movable shelf that may be transported to another floor.

If 410 the needed items are present in the same floor, where the items are needed, the method may continue to palletizing 416 the needed items from the shelf system to a movable shelf of a shelf lift for transportation the items on the movable shelf to the location, where the items are needed. The needed items may be palletized on the movable shelf by a palletless lift. It should be appreciated that the items may be palletized on the movable shelf before the need for items has occurred, whereby it may be sufficient to deter- mine that the items are on the movable shelf that may be transported to the needed location.

The method may end 418 after the needed items are palletized on the movable shelf. Thanks to the items being palletized by the palletless lift on the movable shelf operated by the shelf lift, items may be stocked as needed to avoid outages of items on the movable shelves.

Figure 5 illustrates guides 504 in a shelf system according to an embodiment. The guides 504 facilitate docking a palletless lift to a movable shelf. The guides are illustrated in a structure 502. The structure may be a movable shelf, for example an edge of the shelf, or the structure may be a fixed structure at the parking position of the shelf system. When the guides are arranged fixed to the parking positions, the guides may be used for positioning the palletless lift even if the movable shelf is not present at the parking position. In this way freedom may be provided to the positioning of the palletless lift with respect to the shelf system. The palletless lift may have one or more sensors that allow detection of the guides and positioning the palletless lift to the guides. The guides may be arranged in the width direction of the movable shelf.

The guides may be holes 504 in the structure such that protrusions from the lift may enter the guides for docking the lift to the movable shelf. The holes may be through-holes or recesses. The protrusion may extend in the depth direction of the movable shelf and be received within the holes. Accordingly, the holes may be open towards the protrusions. After the protrusions are received in the holes, the palletless lift may be docked to the movable shelf.

Figures 6a and 6b illustrates positions of guides 608, 610 in a shelf system 600 according to embodiments. The shelf system may comprise at least one movable shelf 602 and one or more parking positions 604 for the movable shelves. The guides may be arranged in the width direction 'w' of the movable shelf. In Figures 6a and 6b the movable shelf may be parked in the parking position such that a palletless item in a palletless lift 606 is capable to be moved by sliding from the palletless lift to the movable shelf docked at the parking position or vice versa. In Figure 6a, the shelf system comprises guides 608 fixed at the parking position. The guides may be fixed to a horizontal beam in the shelf system for example. In Figure 6b guides 610 are arranged at the movable shelf. In the movable shelf the guides may be arranged at one or more edges of the movable shelf. In Figure 6 and 6b the guides are preferably arranged in the shelf system to a side, where the palletless lift is operating palletless items.

The palletless lift may comprise one or more protrusions 612 for docking the lift to the movable shelf by the protrusions entering the guides. The protrusions may be extensible and retractable in the protruding direction such that they may be extended for docking the palletless to the movable shelf and retracted for undocking the palletless lift way from the movable shelf. The pal- letless lift may comprise a unit for horizontal movement 614 of the lift for moving the palletless lift towards the movable shelf and to a position for communicating palletless items from the lift to the movable shelf at the parking position or at the operating station or for communicating palletless items from the park- ing positon or movable shelf to the palletless lift. The unit for horizontal movement may be caused to actuate after the protrusions have engaged the guides. When the protrusions are engaged to the guides, the palletless lift may be maintained at the parking position, whereby the unit for horizontal movement may cause the palletless lift to move the palletless lift towards the movable shelf. In this way a gap between the palletless lift and the movable shelf may be decreased for facilitating communications of palletless items between the lift and the palletless lift. In one example the unit for horizontal movement comprises an electric motor connected to the protrusions for driving the protrusions towards the guides and away from the guides, and an electric motor for driving the palletless lift towards the movable shelf and away from the movable shelf. A single electric motor may be sufficient for driving both the protrusions and the palletless lift.

In an embodiment, the guides comprise holes arranged in a width direction of the movable shelves and the palletless lift has protrusions for penetrating and engaging to the holes and a unit for horizontal movement of the lift towards the shelves. The unit for horizontal movement is caused to actuate after the protrusions have engaged the holes.

Figures 7a and 7b illustrate partitioners 702 for palletizing palletless variable size items to a movable shelf 704 according to embodiments. The movable shelf may be a shelf in a shelf system in an arrangement according to an embodiment. Figure 7a is a view from one end of the movable shelf. Thereby the width direction of the movable shelf is into the page. Figure 7b is a view from above the movable shelf. The movable shelf comprises partitioners 702. The partitioners 702 maybe installed to one or more movable shelves 704 in the shelf system for partitioning the movable shelves and receiving a grabber 706 from the lift for transporting and engaging palletless items. The partitioners may extend in the depth 'd' direction of the movable shelf such that a pair of partitioners may form a partition on the movable shelf in the space between the partitioners in the width direction 'w _p i ', 'w _P 2' of the movable shelf. In this way, the partitioners prevent movement of items in the width direction of the movable shelf and reserve space for the grabber of the palletless lift. The partition- ers may be at least partly elevated to a height 'h' from an upper surface of the movable shelf and open to the side of the movable shelf, where the palletless lift operates such, such that the grabber may be received between the partitioners and the upper surface of the movable shelf. The partitioners may be of sufficient width such that grabber may enter in the depth direction of the movable shelf between the partitioners and the movable shelf. In this way the partitioners 702 provide that space is reserved for the grabber on the movable shelf on both sides of the item located in the partition.

A grabber 706 of the palletless lift may comprise gripping members for transporting and engaging palletless variable size items. The gripping members may be movable in the width direction of the movable shelf 'w _p i \ 'w _P 2', for engaging an item between the gripping members. The gripping members may be movable in the depth 'd' direction of the movable shelf for moving an item between the gripping members from the palletless lift to the movable shelf or from the movable shelf to the palletless lift. When an item is engaged between the gripping members, the item is engaged by the gripping members pressing the item from opposite sides of the item. When the item is not engaged between the gripping members, the gripping members may be separated in the width direction 'w _p i \ 'w _P 2', of the movable shelf. The separation of the gripping members in width direction may be defined by the width of the 'w _p i \ 'w _P 2' partition the palletless lift is parked at. In this way the gripping members may be received under the partitioners, between the partitioners and the movable shelf, according to the width of each partition.

An embodiment concerns operating a palletless lift to transport pal- letless items to and/from a movable shelf. The palletless lift may be operated under control of a warehouse management system.

Transporting a palletless item from the movable shelf may comprise collecting the item by the palletless lift from the movable shelf. The movable shelf may comprise partitioners. The palletless lift may be docked to the mova- ble shelf guided by guides after which the gripping members may be extended from the palletless lift towards the movable shelf and received under the partitioners. The gripping members may engage the item in the partition by moving the gripping members separated in the width direction of the movable shelf towards each other. The gripping members may engage the items and exert a force to the item sufficient to hold the item between the gripping members. Then the grabber move back and pull the item to the palletless lift. Transporting a palletless item from the movable shelf may comprise stocking the palletless item by a palletless lift to the movable shelf. The movable shelf may comprise partitioners. The palletless lift may be docked to the movable shelf guided by guides. The gripping members may be engaged to the palletless item carried in the palletless lift. The gripping members may be extended from the palletless lift towards the movable shelf and push the item from the palletless lift on the movable shelf. After the palletless item is on the movable shelf, the gripping members may be moved apart in the width direction of the movable shelf and under the partitioners. Then the gripping mem- bers may be retracted back to the palletless lift.

Figure 8 illustrates a method according to an embodiment. The embodiment may be performed in an arrangement described above for example by a warehouse management system. The method provides stocking palletless items to a movable shelf and/or collecting palletless items from the movable shelf.

The method may start 800, when a palletless lift is operational and capable of transporting and engaging palletless variable size items. The items may be located on a movable shelf of the shelf system or at an operating station, where the items maybe engaged for transportation by the palletless lift.

The palletless lift may be controlled 802 for transporting and engaging palletless variable size items. The palletless items may be engaged and transported by the palletless lift between an operating station and a shelf of the shelf system, and between shelves of the shelf system. Shelves and shelf systems may be located in different floors, whereby the palletless items may be palletized to a movable shelf movable between the different floors by a shelf lift.

The palletless lift may be docked 804 to a movable shelf of the shelf system. The shelf system may have guides for positioning the palletless lift to a parking position of the movable shelf. The palletless lift may comprise protru- sions for engaging the guides and a unit for horizontal movement that may be caused to actuate after the protrusions have engaged the guides. Actuating the unit for horizontal movement may cause moving the palletless lift towards the movable shelf.

When the palletless lift is docked to the movable shelf, items may be stocked from the palletless lift to the movable shelf and/or collected from the movable shelf to the palletless lift. Accordingly, items may be communicated between the movable shelf and the palletless lift docked to the movable shelf.

The method may end 806 after communication of items to/from the palletless lift is provided and stocking palletless items to a movable shelf and/or collecting palletless items from the movable shelf is facilitated.

In an embodiment there is provided a computer program comprising computer program code for execution on a computer to cause a method according to an embodiment. The computer program may be embodied on a computer -readable storage medium.

In an embodiment there is provided a computer program product for a computer, comprising a computer program according to an embodiment.

In an embodiment, an apparatus or arrangement, for example a warehouse management system described in an embodiment, may comprise at least one processor, memory and a computer program code that form processing means or a computer for carrying out an embodiment.

Embodiments as described may be carried out in the form of a computer process defined by a computer program. The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, which may be any entity or device capable of carrying the program. For example, the computer program may be stored on a computer -readable storage medium. The computer -readable storage medium may be a computer program distribution medium readable by a computer or a processor. The computer -readable storage medium may be, for example but not limited to, a record medium, computer memory, read-only memory, electrical carrier signal, telecommunications signal, and software distribution package, for example.

The techniques described herein may be implemented by various means so that an arrangement, warehouse management system or a unit of the arrangement or the warehouse management system implementing one or more functions of an arrangement or warehouse management system de- scribed with an embodiment comprises not only prior art means, but also means for implementing the one or more functions of a corresponding apparatus or unit described with an embodiment and it may comprise separate means for each separate function, or means may be configured to perform two or more functions. For example, these techniques may be implemented in hardware (one or more apparatuses), firmware (one or more apparatuses), software (one or more modules), or combinations thereof. In one example im- plementation, an arrangement or warehouse management system, or a unit of the arrangement or warehouse management system may be a software application that is executable on a platform. The platform may be a software and/or hardware platform capable of executing software applications. A computer may be an example of a hardware platform. A software platform may comprise, for example an operating system. A combination of hardware and software platform may be formed by an operating system that is executable on a computer. Examples of the software platforms include operating systems, for example OSX from Apple Inc., and Windows Vista from Microsoft.

For a firmware or software, implementation can be through modules

(e.g., procedures, functions, and so on) that perform the functions described herein. The computer program codes may be stored in any suitable, processor/computer-readable data storage medium(s) or memory unit(s) or article(s) of manufacture and executed by one or more processors/computers. The data storage medium or the memory unit may be implemented within the processor/computer or external to the processor/computer, in which case it can be communicatively coupled to the processor/computer via various means as is known in the art.

It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.