METHOD OF OPERATING AN AUTOMATED STORAGE AND RETRIEVAL SYSTEM

Abstract

A method of operating an automated storage and retrieval system includes: a rail system including a first set of parallel rails arranged in a horizontal plane and extending in a first direction, and a second set of parallel rails arranged in the horizontal plane and extending in a second direction which is orthogonal to the first direction, which first and second sets of rails form a grid pattern in the horizontal plane including a plurality of adjacent grid cells, a central control unit configured to receive, transmit and process data signals of a plurality of container handling vehicles for handling storage containers of the automated storage and retrieval system. Each container handling vehicle includes a vehicle body, a wheel assembly provided on the vehicle body, the wheel assembly being configured to move the vehicle along the rail system in both of the first direction and the second direction, a vehicle control unit configured to receive data signals from, transmit data signals to and process data signals of the central control unit, and a proximity sensor system configured to detect another container handling vehicle of said plurality of container handling vehicles and determine whether or not it is within a predetermined distance. The method includes detecting with the central control unit that access of a first container handling vehicle to a target cell, which is one of the plurality of grid cells, is blocked by a second container handling vehicle, transmitting a data signal from the central control unit to the vehicle control unit of the first container handling vehicle commanding the first container handling vehicle to move into the target cell when the second container handling vehicle is beyond said predetermined distance.

Claims

1. A central control unit, for an automated storage and retrieval system, configured to receive, transmit and process data signals of a plurality of vehicle control units of a plurality of respective container handling vehicles for handling storage containers of the automated storage and retrieval system, and further configured to: detect, based on information from a vehicle control unit of a first container handling vehicle, that access of the first container handling vehicle to a target cell of a plurality of grid cells of the automated storage and retrieval system is blocked by a second container handling vehicle; and transmit, to the vehicle control unit of the first container handling vehicle, a data signal commanding the first container handling vehicle to move into the target cell when the second container handling vehicle is beyond a predetermined distance.

2. An automated storage and retrieval system comprising: the central control unit according to claim 1; a rail system comprising a first set of parallel rails arranged in a horizontal plane and extending in a first direction, and a second set of parallel rails arranged in the horizontal plane and extending in a second direction which is orthogonal to the first direction, which first set of parallel rails and second set of parallel rails form a grid pattern in the horizontal plane comprising a plurality of adjacent grid cells; and a plurality of container handling vehicles.

3. The automated storage and retrieval system according to claim 2, wherein each container handling vehicle comprises: a vehicle body; a wheel assembly provided on the vehicle body, the wheel assembly being configured to move each container handling vehicle along the rail system in both of the first direction and the second direction; a vehicle control unit configured to receive data signals from, transmit data signals to and process data signals of the central control unit; and a proximity sensor system configured to detect another container handling vehicle of said plurality of container handling vehicles and determine whether or not it is within the predetermined distance.

4. The automated storage and retrieval system according to claim 3, where the predetermined distance is measured from a side surface of a container handling vehicle in a direction of the first set of parallel rails and the second set of parallel rails.

5. The automated storage and retrieval system according to claim 4, where each container handling vehicle comprises four vertical side surfaces: a first side surface facing a positive first direction, a second side surface facing a negative first direction, a third side surface facing a positive second direction, and a fourth side surface facing a negative second direction, wherein the positive first direction and the negative first direction are opposite of each other, wherein the positive second direction and the negative second direction are opposite of each other, and wherein the first side surface and the second side surface extend between the third side surface and the fourth side surface such that the side surfaces form a rectangular cross section in a horizontal plane.

6. The automated storage and retrieval system according to claim 5, wherein the proximity sensor system comprises at least any of: a first part sensor system directed outwards from the first side surface in the positive first direction and being capable of detecting another container handling vehicle within said predetermined distance from the first side surface, a second part sensor system directed outward from the second side surface in the negative first direction and being capable of detecting another container handling vehicle within said predetermined distance from the second side surface, a third part sensor system directed outwards from the third side surface in the positive second direction and being capable of detecting another container handling vehicle within said predetermined distance from the third side surface, and a fourth part sensor system directed outwards from the fourth side surface in the negative second direction and being capable of detecting another container handling vehicle within said predetermined distance from the fourth side surface.

7. The automated storage and retrieval system according to claim 5, wherein at least one of: the proximity sensor system comprises at least two proximity sensors, wherein each of the at least two proximity sensors are arranged to detect another container handling vehicle at boundaries of any of the first side surface, the second side surface, the third side surface, and the fourth side surface that is in the horizontal plane; the rectangular cross section of any of the first container handling vehicle or the second container handling vehicle corresponds to an integer multiple of grid cells; or the rectangular cross section of any of the first or second container handling vehicles corresponds to more than one grid cell.

8. The central control unit according to claim 1, wherein the central control unit is further configured to: transmit a data signal to a vehicle control unit of the second container handling vehicle commanding the second container handling vehicle to move clear of the target cell.

9. The central control unit according to claim 8, wherein the central control unit is further configured to: transmit a data signal to the vehicle control unit of the second container handling vehicle commanding the second container handling vehicle to at least one of: move clear of the target cell and to another grid cell; move in a direction parallel to the direction between the target cell and the first container handling vehicle; or move in a direction orthogonal to the direction between the target cell and the first container handling vehicle.

10. The central control unit according to claim 1, wherein the central control unit is further configured to transmit a data signal to the vehicle control unit of the first container handling vehicle to specify the predetermined distance.

11. A vehicle control unit of a first container handling vehicle for handling storage containers of an automated storage and retrieval system, the vehicle control unit being configured to receive and transmit data signals from a central control unit of the automated storage and retrieval system, and further configured to: receive, from the central control unit, a data signal commanding the first container handling vehicle to move into a target cell that is blocked by a second container handling vehicle when the second container handling vehicle is beyond a predetermined distance; detecting that the second container handling vehicle is beyond the predetermined distance; and responsive to the detecting, causing the first container handling vehicle to move into the target cell that was blocked by the second container handling vehicle.

12. The vehicle control unit according to claim 11, wherein the automated storage and retrieval system comprises a rail system comprising a first set of parallel rails arranged in a horizontal plane and extending in a first direction, and a second set of parallel rails arranged in the horizontal plane and extending in a second direction which is orthogonal to the first direction, which first set of parallel rails and second set of parallel rails form a grid pattern in the horizontal plane comprising a plurality of adjacent grid cells, and wherein the predetermined distance is measured from a side surface of a container handling vehicle in a direction of a rail of the first set of parallel rails or the second set of parallel rails.

13. The vehicle control unit according to claim 12, where each container handling vehicle comprises four vertical side surfaces: a first side surface facing a positive first direction, a second side surface facing a negative first direction, a third side surface facing a positive second direction, and a fourth side surface facing a negative second direction, wherein the positive first direction and the negative first direction are opposite of each other, wherein the positive second direction and the negative second direction are opposite of each other, and wherein the first side surface and the second side surface extend between the third side surface and the fourth side surface such that the first side surface, the second side surface, the third side surface, and the fourth side surface form a rectangular cross section in a horizontal plane.

14. The vehicle control unit according to claim 13, wherein the vehicle control unit is in communication with a proximity sensor system comprising at least any of: a first part sensor system directed outwards from the first side surface in the positive first direction and being capable of detecting another container handling vehicle within said predetermined distance from the first side surface, a second part sensor system directed outward from the second side surface in the negative first direction and being capable of detecting another container handling vehicle within said predetermined distance from the second side surface, a third part sensor system directed outwards from the third side surface in the positive second direction and being capable of detecting another container handling vehicle within said predetermined distance from the third side surface, and a fourth part sensor system directed outwards from the fourth side surface in the negative second direction and being capable of detecting another container handling vehicle within said predetermined distance from the fourth side surface.

15. The vehicle control unit according to claim 14, wherein at least one of: the vehicle control unit is in communication with the proximity sensor system comprising at least two proximity sensors, wherein each of the at least two proximity sensors are arranged to detect another container handling vehicle at boundaries of any of the first side surface, the second side surface, the third side surface, or the fourth side surface that is in the horizontal plane; the rectangular cross section of any of the first container handling vehicle or the second container handling vehicle corresponds to an integer multiple of grid cells; or the rectangular cross section of any of the first or second container handling vehicles corresponds to more than one grid cell.

16. The vehicle control unit according to claim 11, wherein the vehicle control unit is further configured to continuously monitor, based on information from a proximity sensor system of the first container handling vehicle, as it moves into the target cell, to detect if the second container handling vehicle is within the predetermined distance.

17. The vehicle control unit according to claim 14, where the proximity sensor system of the first container handling vehicle is configured to measure the predetermined distance from a side surface of a plurality of side surfaces of the first container handling vehicle and wherein the predetermined distance is defined in a direction of a rail of the first set of parallel rails or the second set of parallel rails.

18. The vehicle control unit according to claim 17, wherein the vehicle control unit is further configured to determine, based on information from the vehicle control unit from which side surface of the first container handling vehicle to detect the second container handling vehicle.

19. A container handling vehicle comprising: the vehicle control unit according to claim 12; a vehicle body; a wheel assembly provided on the vehicle body, the wheel assembly being configured to move the vehicle along the rail system in both of the first direction and the second direction; and a proximity sensor system configured to detect another container handling vehicle of said plurality of container handling vehicles and determine whether or not it is within a predetermined distance.

20. A non-transitory computer-readable storage medium comprising instructions which, when executed, cause performance of: a method comprising: detecting, based on information from a vehicle control unit of a first container handling vehicle, that access of the first container handling vehicle to a target cell of a plurality of grid cells is blocked by a second container handling vehicle; and transmitting, to the vehicle control unit of the first container handling vehicle, a data signal commanding the first container handling vehicle to move into the target cell when the second container handling vehicle is beyond a predetermined distance; or a method comprising: receiving, from a central control unit, a data signal commanding the first container handling vehicle to move into a target cell that is blocked by a second container handling vehicle when the second container handling vehicle is beyond a predetermined distance; detecting that the second container handling vehicle is beyond the predetermined distance; and responsive to the detecting, causing the first container handling vehicle to move into the target cell that was blocked by the second container handling vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Following drawings are appended by way of example only to facilitate the understanding of the invention.

[0099] FIG. 1 is a perspective view of a grid of a prior art automated storage and retrieval system.

[0100] FIG. 2a is a perspective view of a prior art container handling vehicle having a centrally arranged cavity for containing storage containers therein.

[0101] FIG. 2b is a perspective view of a prior art container handling vehicle having a cantilever for containing storage containers underneath.

[0102] FIG. 3 is a top view of a prior art single rail grid.

[0103] FIG. 4 is a top view of a prior art double rail grid.

[0104] FIG. 5 is a schematic illustration of the four vertical side surfaces formed by a container handling vehicle with an irregular projection on the horizontal plane of the rail system.

[0105] FIG. 6 is a perspective view of a container handling vehicle schematically illustrating side surfaces and possible locations of a proximity sensor system.

[0106] FIG. 7 is a perspective view of a container handling vehicle schematically illustrating side surfaces and possible locations of a proximity sensor system.

[0107] FIG. 8a is a side view of a container handling vehicle comprising a protruding section, schematically illustrating side surfaces on said vehicle.

[0108] FIG. 8b is a perspective view of two container handling vehicles, of the same type shown in FIG. 8a, operating on adjacent rows of grid cells.

[0109] FIG. 9a is a perspective view of a container handling vehicle for container delivery, schematically illustrating side surfaces on said vehicle.

[0110] FIG. 9b is a perspective view of a storage system comprising a cantilever container handling vehicle operating on a rail system of a grid, and a container handling vehicle for container delivery operating [0111] on a lower rail system.

[0112] FIG. 10 is a schematic top view of a rail system, illustrating the projection and side surfaces formed by several different container handling vehicles.

[0113] FIG. 11 is a flow chart illustrating the steps of a method of operating an automated storage and retrieval system.

[0114] FIGS. 12a through 12d are each a schematic top view of a rail system, illustrating steps of a method where the container handling vehicles move in the same direction.

[0115] FIGS. 13a through 13d are each a schematic top view of a rail system, illustrating steps of a method similar to FIGS. 12a-12d but where the second container handling vehicle occupies a cell adjacent to a target cell.

[0116] FIGS. 14a through 14d are each a schematic top view of a rail system, illustrating steps of a method similar to FIGS. 12a-12d but where the second container handling vehicle partially occupies a target cell.

[0117] FIGS. 15a through 15d are each a schematic top view of a rail system, illustrating the steps of a method where the container handling vehicles move in an orthogonal direction to each other.

[0118] In the drawings, like reference numerals have been used to indicate like parts, elements or features unless otherwise explicitly stated or implicitly understood from the context.

DETAILED DESCRIPTION OF THE INVENTION

[0119] In the following, embodiments of the invention will be discussed in more detail by way of example only and with reference to the appended drawings. It should be understood, however, that the drawings are not intended to limit the invention to the subject-matter depicted in the drawings.

[0120] The framework 100 of the automated storage and retrieval system 1 is constructed in accordance with the prior art framework 100 described above in connection with FIGS. 1-4, i.e. a number of upright members 102 and a number of horizontal members 103, which are supported by the upright members 102, and further that the framework 100 comprises a rail system 108 of parallel rails 110,111 in X direction and Y direction arranged across the top of storage columns 105/grid columns 112. The horizontal area of a grid column 112, i.e. the area along the X and Y directions, may be defined by the distance between adjacent rails 110 and 111, respectively (see FIGS. 3 and 4).

[0121] In FIG. 1 the grid 104 is shown with a height of eight cells. It is understood, however, that the grid 104 in principle can be of any size. In particular it is understood that grid 104 can be considerably wider and/or longer and/or deeper than disclosed in FIG. 1. For example, the grid 104 may have a horizontal extent of more than 700700 grid cells and a depth of more than twelve grid cells.

[0122] The grey area of FIG. 5 illustrates the projection 6 onto a horizontal plane of an irregularly shaped container handling vehicle 400 and the side surfaces 7,8,9,10 parallel to the first direction X and the second direction Y, on the tangent of the projection 6, thereby forming a rectangular cross section 11 represented by the full line. Accordingly, a first side surface 7 and a second side surface 8 are parallel to a vertical plane V, illustrated by a dashed line, which is also parallel to the second direction Y, whilst a third side surface 9 and a fourth side surface 10 are parallel to vertical plane V, illustrated by another dashed line orthogonal to the one previously mentioned, which is also parallel to the first direction X. The projection 6 illustrates the outermost lateral blocking extent of the container handling vehicle in the first direction X and second direction Y, i.e. the outermost points of the container handling vehicle where another vehicle cannot pass by. As illustrated by the example along the first positive direction X+, the predetermined distance D is measured from the first side surface 7 independent of the shape of the container handling vehicle. As a proximity sensor system 4 on the container handling vehicle illustrated FIG. 5 cannot physically be arranged along the first side surface 7, the distance from a sensor in the proximity sensor system 4 to the side surface 7 needs to be accounted for.

[0123] As shown in FIG. 5 the proximity sensor system 4 is arranged to detect along an entire side surface 7,8,9,10. The first side surface 7 thus faces a positive first direction X+, a second side surface 8 faces a negative first direction X, a third side surface 9 faces a positive second direction Y+ and a fourth side surface 10 facing a negative second direction Y. The negative directions are oriented oppositely to their respective positive directions. The side surfaces 7,8,9,10 combined form a rectangular cross section 11 in the horizontal plane P such that the first side surface 7 and the second side surface 8 extend between the third side surface 9 and the fourth side surface 10 and vice versa.

[0124] As illustrated in FIG. 5, the directions of detection of the proximity sensor system 4 are represented by the arrows pointing out from the side surfaces 7,8,9,10. Thus, a first part sensor system 4X+ is arranged to detect along the first side surface 7 in a positive first direction X+, a second part sensor system 4X is arranged to detect along the second side surface 8 in a negative first direction X, a third part sensor system 4Y+ is arranged to detect along a third side surface 9 in a positive second direction Y+ and a fourth part sensor system 4Y is arranged to detect along the fourth side surface 10 in a negative second direction Y.

[0125] FIG. 6 is a perspective view of a container handling vehicle 101, illustrating how the side surfaces 7,8,9,10 may be defined on this type of container handling vehicle 101. The dashed lines represent the horizontal and vertical borders of the side surfaces 7,8,9,10, and as shown, the side surfaces 7,8,9,10 are parallel to respective vertical planes V and the respective first direction X and second direction Y. In this embodiment, the side surfaces 7,8,9,10 thus generally correspond to the physical side surfaces of the container handling vehicles 101 exterior housing, but as will be understood by the person skilled in the art, this may not always be the case, especially for an irregularly shaped container handling vehicle 400. A coordinate system is inserted in FIG. 6 to illustrate how the second side surface 8 faces the first negative direction X, and the fourth side surface 10 faces the negative second direction Y. It should however be noted that the coordinates and the orientation of the container handling vehicle 101 in FIG. 6 are merely an example to illustrate how side surfaces 7,8,9,10 may be defined on a container handling vehicle 101. The definition of which side is which, is dependent on the orientation of the container handling vehicle 101 as it is placed on a grid 104, which gives the frame of reference as to what are the positive and negative first X, second Y and third Z directions. Four sensors 17 of the proximity sensor system 4 are exemplified as each being arranged in an upper corner of each side surface 8,10 of the exterior housing of the container handling vehicle 101. As will be apparent, similar sensors may be found on the sides 7 and 9 of the container handling vehicle 101 not shown in FIG. 6. Advantageously, the sensors 17 are arranged near the boundary of a side surface 7,8,9,10 as this allows them to detect the presence of another container handling vehicle moving parallel to said side surface.

[0126] In an alternative embodiment of the present invention the proximity sensor is placed on the top most surface of the container handling vehicle. In this embodiment a single proximity sensor can be used. This proximity sensor can be tilted or rotated in order to cover the entire 360 area around the container handling vehicle.

[0127] In yet another embodiment of the present invention four proximity sensors can be placed on the top most surface of the container handling vehicle. Using four sensors it is possible to cover the entire 360 area around the container handling vehicle without having to move the sensors. Each sensor covers one side of the container handling vehicle. A first proximity sensor is directed outwards in the positive first direction and is capable of detecting another container handling vehicle within said predetermined distance from the first side surface, and a second proximity sensor is directed outwards in the negative first direction and being capable of detecting another container handling vehicle within said predetermined distance from the second side surface, and a third proximity sensor is directed outwards in the positive second direction and being capable of detecting another container handling vehicle within said predetermined distance from the third side surface, and a fourth proximity sensor is directed outwards in the negative second direction and being capable of detecting another container handling vehicle within said predetermined distance from the fourth side surface.

[0128] FIG. 7 is a perspective view of a container handling vehicle 201, illustrating how the side surfaces 7,8,9,10 may be formed on this type of container handling vehicle 201. In this embodiment, it should be noted that the side surfaces 7,8,9,10 do not generally correspond to the exterior housing of the container handling vehicle 201, apart from the second side surface 8. Due to the cantilever construction of this container handling vehicle 201, it is the outermost part of the cantilever 202 which defines the third side surface 9 since it extends over a grid cell 122 and blocks other container handling vehicles from occupying that cell 122. The fourth side surface 10 thus also extends from the edge of the cantilever 202 to the second side surface 8. Three sensors 17 of the proximity sensor system 4 are exemplified as each being arranged in an upper corner of the second side surface 8 and third side surface 9 of the exterior housing of the container handling vehicle 201, whilst a fourth sensor 17 is arranged near the edge of the cantilever 202. As will be apparent, similar sensors 17 may be found on the sides 7 and 9 not fully shown in FIG. 7, with sensors 17 also being arranged in the outermost edge of the cantilever 202 facing the positive first direction X+. Advantageously, the sensors 17 are arranged near the boundary of a side surface 7,8,9,10 as this allows them to detect the presence of another container handling vehicle moving parallel to said side surface 7,8,9,10.

[0129] In an alternative embodiment of the present invention the proximity sensor is placed on the top most surface of the container handling vehicle. In this embodiment a single proximity sensor can be used. This proximity sensor can be tilted or rotated in order to cover the entire 360 area around the container handling vehicle.

[0130] In yet another embodiment of the present invention four proximity sensors can be placed on the top most surface of the container handling vehicle. Using four sensors it is possible to cover the entire 360 area around the container handling vehicle without having to move the sensors. Each sensor covers one side of the container handling vehicle. A first proximity sensor is directed outwards in the positive first direction and is capable of detecting another container handling vehicle within said predetermined distance from the first side surface, and a second proximity sensor is directed outwards in the negative first direction and being capable of detecting another container handling vehicle within said predetermined distance from the second side surface, and a third proximity sensor is directed outwards in the positive second direction and being capable of detecting another container handling vehicle within said predetermined distance from the third side surface, and a fourth proximity sensor is directed outwards in the negative second direction and being capable of detecting another container handling vehicle within said predetermined distance from the fourth side surface.

[0131] FIGS. 8a and 8b illustrate another type of container handling vehicle 301 with a contact area against the rail system 108 which has a horizontal extension that is equal to the lateral area defined by a grid column 112 or grid cell 122. The container handling vehicle 301 also comprises a protruding section 302, as shown in FIG. 8a, which extends laterally beyond the contact area of the container handling vehicle 301 and, when the container handling vehicle 301 is positioned above a grid cell 122, into a neighbouring grid cell 122. The container handling vehicle 301 comprises a vehicle body 301a and drive means 301b for driving in the first direction X, and drive means 301c for driving in the second direction Y. Though the drive means 301c in the second direction Y are not shown in the side view of FIG. 8a, they can be seen in FIG. 8b and are similarly arranged as the drive means 301b in the first direction X.

[0132] However, the protruding section 302 does not prevent another container handling vehicle 301 from travelling over the neighbouring grid cell 122, i.e. the grid cell 122 into which the protruding section 302 of the first vehicle extends. To achieve this, the container handling vehicles 301 each comprise a recessed section 303 arranged opposite the protruding section 302, which recessed section 303 is capable of accommodating the protruding sections 302 of other vehicles 301 when they pass over a neighbouring grid cell 122. The recessed section 303 may have a shape which is complementary to the shape of the protruding section 302 and may extend across the whole width or length of the container handling vehicle 301, thus allowing vehicles 301 to pass each other over adjacent grid cells 122. When the vehicles 301 operate on the rail system 108, the recessed section 303 of each container handling vehicle 301 is capable of accommodating the protruding sections 302 of other container handling vehicles 301 when they pass over a neighbouring grid cell 122, thus allowing container handling vehicles 301 to travel along neighbouring rows of grid cells, as illustrated in FIG. 8b.

[0133] The container handling vehicle 301 in FIGS. 8a and 8b is included herein to illustrate that a protruding section 302 does not necessarily block access to an adjacent grid cell 122, but that this is dependent on the shape of the container handling vehicle. It will therefore be apparent to the person skilled in the art that other variations of container handling vehicles with protrusions, or even without corresponding recesses, can be employed on a rail system 108 without the protrusions acting to block other container handling vehicles from accessing adjacent grid cells 122. The difference between the container handling vehicles of FIGS. 7 and 8 is therefore noteworthy, as both comprise parts extending over an adjacent grid cell 122, yet only the container handling vehicle 201 of FIG. 7 has a side surface 9 defined from the edge of the cantilever 202, contrary to the container handling vehicle 301 of FIG. 8a, FIG. 8b, where the first side surface 7 is not defined by the outermost edge of the protruding section 302.

[0134] FIGS. 9a and 9b illustrate another aspect of a container handling vehicle according to the invention, where a container handling vehicle 601 for container delivery, is shown in FIG. 9a and in relation to an automated storage and retrieval system 1 in FIG. 9b.

[0135] As FIG. 9a illustrates, the container delivery vehicle 601 is arranged for top-down receival of a storage container 106, and therefore comprises a container carrier 602 arranged above a vehicle body 601a to receive a storage container 106. The container delivery vehicle 601 comprises drive means 301b in first direction X, and drive means 301c in the second direction Y similar to that of the other aforementioned container handling vehicles 101,201,301. Side surfaces 7,8,9,10 are defined for the container delivery vehicle 601 as for the other container handling vehicles, with the second 8 and fourth 10 side surfaces visible in FIG. 9a. Possible proximity sensor locations are also illustrated by reference 17.

[0136] FIG. 9b illustrates a container delivery vehicle 601 operating on a rail system 108 below the rail system 108 of a storage grid 104. The delivery rail system 50 may be constructed in the same way or a similar way as the rail system 108 for the container handling vehicles 200,300.

[0137] A container handling vehicle 201, according to the embodiment of FIG. 2b is shown operating on the rail system 108 of the storage grid 104. However, as will be apparent to the person skilled in the art, any kind of container handling vehicle 101,201,301 may be operated on the rail system 108 of the grid, for example according to the embodiments illustrated in FIGS. 6-8. The container handling vehicles 201 may thus lower storage containers down to container delivery vehicles 601 operated on the lower rail system 108. The container delivery vehicles 601 are typically arranged for delivery of storage containers 106 to an access point (not shown) at the periphery of the rail system 108, where the storage containers 106 may be picked. Though not illustrated herein, the lower rail system 108 typically comprises a multitude of container delivery vehicles 601, and as they move between cells below port columns and access points on the periphery of the lower rail system 108, problems of congestion and queuing may arise. Thus, the invention is advantageously applied to rail systems 108 with container delivery vehicles 601 in a similar manner as for container handling vehicles 101,201,301 of a rail system 108 of a grid 104.

[0138] FIG. 10 illustrates the projection 6 on a rail system, side surfaces 7,8,9,10 and rectangular cross sections 11 formed by several different examples of container handling vehicles. The rectangular cross section 11 labelled A could for example be from the container handling vehicle 101 of FIG. 2a, FIG. 6 or FIG. 9a, FIG. 9b, as the rectangular cross section 11 formed by its side surfaces is equal to the lateral area defined by a grid cell 122. The rectangular cross section 11 labelled B is equal to the area defined by one (in the X direction) times one and a half (in the Y direction) grid cells 122, and could for example be from a container handling vehicle with some similarities to the one illustrated in FIG. 2a but where one side wall of the vehicle is enlarged and takes up the area of half a grid cell 122. The rectangular cross section 11 labelled C has an irregular projection and may be of a container handling vehicle 400 similar to that of the illustrative example of FIG. 5. The rectangular cross section 11 labelled D, could for example be from the container handling vehicle 201 of FIG. 2b or FIG. 7. However, it is conceivable that a container handling vehicle similar to that of FIG. 2a, with a lateral area corresponding to two grid cells 122 and capable of lifting two storage containers 106 simultaneously from adjacent grid cells 122 could also form a rectangular cross section 11 as that labelled D. As will be apparent to the person skilled in the art based on the disclosure of the invention herein, many more variations of container handling vehicles are conceivable.

[0139] FIG. 11 is a flow diagram schematically representing the steps of a method for operating an automated storage and retrieval system 1. The method is typically initiated by a step 700 where the central control unit 15 detects a conflict over a grid cell 122 by two container handling vehicles 2,3. A container handling vehicle on route to a target cell 12 is labelled as a first container handling vehicle 2, and the container handling vehicle blocking access to the target cell 12 of the first container handling vehicle 2 is labelled as a second container handling vehicle 3. A target cell may typically be a grid cell 122, on rail system 108,108, where a container handling vehicle has received a command from the central control unit 15 to move. In the next step, the first container handling vehicle 2 moves to a grid cell 122 adjacent to its target cell 12, and receives a data signal from the central control unit 15 which it processes in its vehicle control unit 14. The data signal comprises a command to activate the first container handling device's 2 proximity sensor system 4, i.e. to start monitoring for another container handling vehicle in the direction of the target cell 12 which coincides with its the direction of travel. The data signal may also comprise specification of a predetermined distance D within which the first container handling vehicle 2 is to detect the second container handling vehicle 3 and to move into the target cell 12 once the second container handling 3 vehicle is beyond said distance D. Another data signal is transmitted from the central control unit 15 to the vehicle control unit 14 of the second container handling vehicle 3 commanding the second container handling vehicle 3 to move clear of the target cell 12. In some aspects, the second container handling vehicle 3 may have already received a command to move clear of the target cell 12 before first container handling vehicle 2 receives a command to activate its proximity sensor system 4 and move, but the second container handling vehicle 3 has not yet moved, for example because it is busy lowering or lifting storage containers 106. Thus the data signal from the central control unit to the first container handling vehicle 2 is illustrated by step 710, and the activation of its proximity sensor system 4 by step 720. In any case, the second container handling vehicle 3 moves away from its blocking position of the target cell 12, as illustrated by step 730. The vehicle control unit 14 of the first container handling vehicle 2 continuously monitors data from its proximity sensor system 4, and upon the predetermined distance D being free from an object i.e. the second container handling vehicle 3, the vehicle control unit 14 controls the first container handling vehicle 2 to move into the target cell 12 represented by step 740. Depending on the direction of travel of the second container handling vehicle 3 relative to the first container handling vehicle 3, the vehicle control unit 14 may continue to monitor whether the second container handling vehicle 3 is within the predetermined distance during movement of the first container handling vehicle 2.

[0140] In the following, with reference to FIGS. 12-15, various steps of methods of operating an automated storage and retrieval system are exemplified in accordance with the invention. To illustrate these, a schematic rail system and two of one type of container handling vehicle 2,3 are used throughout FIGS. 12-15. The container handling vehicles 2,3 exemplified in FIGS. 12-15 have a rectangular cross section 11 equal to one by one and a half grid columns (i.e. 11.5), as described in relation to portion B of FIG. 10, and comprise a container receiving space 13 arranged to one side of the vehicle body. The container handling vehicles 2,3 may further comprise a proximity sensor system 4 such as that shown in FIGS. 6-9, but only activated sensors 17 are illustrated in FIGS. 12-15, i.e. sensors which monitor whether the second container handling vehicle 3 is within the predetermined distance D. However, the remaining sensors 17 may also be active during execution of the method.

[0141] FIG. 12 is a schematic top view of a rail system 108, illustrating steps of a method where a first container handling vehicle 2 and a second container handling vehicle 3 are located on adjacent grid cells 122 when the method is initiated, as illustrated in portion A by the central control unit 15 transmitting a data signal to each of the container handling vehicles 2,3. The second container vehicle 3 is illustrated as covering the entire target cell 12, and is oriented such that its container receiving space 13 is also over the target cell 12. Such a starting point as shown in FIG. 12, may be common around ports, where the target cell 12 is located over a port column 19,20 through which storage containers 106 are dropped off and picked up. The first container handling vehicle 2 thus activates it proximity sensor system 4 as represented by the black dots 17 and continuously monitors the predetermined distance D as it moves into the target cell 12 to avoid collision with the second container handling vehicle 3.

[0142] In portion B of FIG. 12, the second container handling vehicle 3 is moving, as illustrated by the arrow and the position of the vehicle 3 across two grid cells 122. The proximity sensor system 4 of the first container handling vehicle 2 is monitoring the presence of the second container handling vehicle 3 within the predetermined distance D, which may typically be set to 2 meters when the container handling vehicles 2,3 move in parallel.

[0143] Portion C of FIG. 12 thus illustrates first container handling vehicle 2 after it has detected that there is no second container handling vehicle 3 within the predetermined distance D, and both container handling vehicles 2,3 are moving across the rail system 108. The first container handling vehicle's 2 proximity sensor system 4 may thus continuously monitor in the first positive direction X+ in order to avoid a collision, for example if the second container handling vehicle 3 should unexpectedly stop. Note that the second container handling vehicle 3 is partially within the target cell 12 when the first container handling vehicle 2 starts to move.

[0144] Portion D of FIG. 12 illustrates the end result of the method, where the first container handling vehicle 2 has moved over the target cell 12 and the second container handling vehicle 3 has moved to a new position on the rail system 108. Typically, the new position for the second container handling vehicle 3 may be related to a new task such as retrieving or depositing a storage container 106 somewhere in the grid 104.

[0145] FIG. 13 is a schematic top view of a rail system 108, illustrating steps of a method where a first container handling vehicle 2 is located on a grid cell 122 adjacent to its target cell 12 which is unoccupied, yet the second container handling vehicle 3 is blocking access to the target cell 12 due to size and thus the rectangular cross section 11 of the first container handling vehicle 2. The steps illustrated by the portions A-B in FIG. 13 are essentially the same as for the steps in FIG. 12, however only the sensor 17 in the corner of the first container handling vehicle 2 which is closest to the second container handling vehicle 3 is required to be activated. The central control unit 14 may transmit the direction of travel and position for the second container handling vehicle 3, whereupon the vehicle control unit 14 of the first container handling vehicle 2 may determine which sensors are required to monitor for the presence of the second container handling vehicle 3 within the predetermined distance. Alternatively, the central control unit 15 may give a direct command to the first container handling vehicle 2 regarding which sensors are to be activated.

[0146] FIG. 14 is a schematic top view of a rail system 108, illustrating steps of a method where a first container handling vehicle 2 is located on a grid cell 122 adjacent to its target cell 12 which is partially occupied by a second container handling vehicle 3, due to the orientations of the two vehicles 2,3 on the rail system 108 being different. The steps illustrated by the potions A-B in FIG. 13 are essentially the same as for the steps in FIG. 14.

[0147] FIG. 15 is a schematic top view of a rail system 108, illustrating steps of a method where a first container handling vehicle 2 and a second container handling vehicle 3 are initially located on adjacent grid cells 122 similarly to the starting point of the method in FIG. 12. Contrary to the steps of FIG. 12 however, the second container handling vehicle 3 moves in a direction orthogonal to the direction in which the first container handling vehicle 2 is to travel, as illustrated in Portion B of FIG. 15. Thus, the first container handling vehicle's 2 sensor 17 arranged in the corner of the direction of travel of the second container handling vehicle 3 is activated. Furthermore, the predetermined distance D which the proximity sensor system 4 is to detect the second container handling vehicle 3 may be less than 2 (two) meters, for example 10 (ten) centimeters, as it is only required to detect when the second container handling vehicle 3 has passed its corner. The vehicle control unit 14 of the first container handling vehicle 2 may receive information from the central control unit 15 regarding the predetermined distance D and which sensor to activate, or the vehicle control unit 14 may determine the distance and which sensors to activate by receiving information regarding the direction of travel of the second container handling vehicle 3. Once the sensor 17 of the first container handling vehicle 2 has detected that there is no obstruction, said container handling vehicle 2 can move into the target cell 12. In a prior art execution of the method illustrated in FIG. 15, the central control unit 15 could not know that the target cell 12 was free until the second container handling vehicle 3 had moved at least to the position illustrated in portion D of FIG. 15, thus leaving the first container handling device 3 to await moving in to the target cell 12 for an excessive amount of time. The steps of the method in FIG. 15 thus clearly illustrate the time saving aspects of the invention.

[0148] The predetermined distance D may be dynamically adapted to the speed the container handling vehicles are moving in. The container handling vehicles are set to have a default predetermined distance D for a given speed. The container handling vehicles themselves will adapt the distance D to the speed they are traveling in.

[0149] In the preceding description, various aspects of a method of operating an automated storage and retrieval system, and an automated storage and retrieval system according to the invention have been described with reference to the illustrative embodiment. However, this description is not intended to be construed in a limiting sense. Various modifications and variations of the illustrative embodiment, as well as other embodiments of the system and the method which are apparent to persons skilled in the art, are deemed to lie within the scope of the present invention as defined by the following claims.

REFERENCE NUMERALS

[0150]

TABLE-US-00001 Reference numerals: 1 Storage and retrieval system 2 First container handling vehicle 3 Second container handling vehicle 4 Proximity sensor system D Predetermined distance 5 Side surface 6 Projection of first container handling vehicle 7 First side surface 8 Second side surface 9 Third side surface 10 Fourth side surface 11 Rectangular extent 12 Target cell 13 Container receiving space 14 Vehicle control unit 15 Central control unit 16 Data signal 17 Proximity sensor 19 Port column 20 Port column 100 Framework structure 101 Container handling vehicle 101a Vehicle body of the container handling vehicle 101 101b Drive means in first direction (X) 101c Drive means in the second direction (Y) 102 Upright members of framework structure 103 Horizontal members of framework structure 104 Grid 105 Storage column 106 Storage container 106 Particular position of storage container 107 Stack 108 Rail system 108 Rail system for delivery vehicle 110 Parallel rails in first direction (X) 110a First rail of neighboring rails 11 110b Second rail of neighboring rails 11 111 Parallel rails in second direction (Y) 111a First rail of neighboring rails 12 111b Second rail of neighboring rails 12 112 Grid column 115 Grid opening 122 Footprint/grid cell/storage cell 201 Cantilever container handling vehicle 201a Vehicle body of the cantilever container handling vehicle 201 201b Drive means in first direction (X) of the cantilever container handling vehicle 201c Drive means in second direction (Y) of the cantilever container handling vehicle 202 Cantilever section 301 Container handling vehicle with protruding section 301a Container handling vehicle body 301b Drive means in first direction (X) of the container handling vehicle with protruding section 301c Drive means in second direction (Y) of the container handling vehicle with protruding section 302 Protruding section 303 Recessed section 400 Irregularly shaped container handling vehicle 601 Remotely operated delivery vehicle 601a Vehicle body of the delivery vehicle 601 602 Container carrier of the delivery vehicle 601 700 Control unit detects conflict 710 Command prepare to move transmitted 720 First vehicle activates sensor system 730 Second vehicle moves clear of target cell 740 First vehicle moves into target cell X First direction X Negative first direction X+ Positive first direction Y Second direction Y+ Positive second direction Y Negative second direction Z Third direction P Horizontal plane P Horizontal plane of delivery vehicle rail system 108 V Vertical plane D Predetermined distance