WO2024227520A1

WO2024227520A1 - A remotely operated vehicle for handling a storage container

Info

Publication number: WO2024227520A1
Application number: PCT/EP2024/051344
Authority: WO
Inventors: Erik STRØMME; Ole-Martin KIRKEBY
Original assignee: Autostore Technology AS
Priority date: 2023-04-28
Filing date: 2024-01-22
Publication date: 2024-11-07

Abstract

A remotely operated vehicle (600) for handling a storage container (106) in an automated storage and retrieval system is provided The remotely operated vehicle (600) comprises wheels, at least one motor (615) and a vehicle control unit (604). The vehicle control unit (604) is configured to operate the at least one motor (615), the at least one motor (615) being operatively coupled with the wheels to move the vehicle (600). The vehicle control unit (604) is configured to limit at least one of a maximum travel speed and a maximum acceleration of the vehicle (600) in at least one direction depending on the weight of a storage container (106) carried by the vehicle (600), such that a tilting of the vehicle (600) and/or wheel skidding is prevented.

Description

A remotely operated vehicle for handling a storage container

FIELD OF THE INVENTION

[001] The present invention relates to a remotely operated vehicle for handling a storage container, a method for operating such a vehicle, an automated storage and retrieval system having at least one vehicle and a computer program.

BACKGROUND AND PRIOR ART

[002] Fig. 1 discloses a prior art automated storage and retrieval system 1 with a framework structure 100 and Figs. 2, 3 and 4 disclose three different prior art container handling vehicles 201,301,401 suitable for operating on such a system 1.

[003] The framework structure 100 comprises upright members 102 and a storage volume comprising storage columns 105 arranged in rows between the upright members 102. In these storage columns 105 storage containers 106, also known as bins, are stacked one on top of one another to form stacks 107. The members 102 may typically be made of metal, e.g. extruded aluminum profiles.

[004] The framework structure 100 of the automated storage and retrieval system 1 comprises a rail system 108 arranged across the top of framework structure 100, on which rail system 108 a plurality of container handling vehicles 201,301,401 maybe operated to raise storage containers 106 from, and lower storage containers 106 into, the storage columns 105, and also to transport the storage containers 106 above the storage columns 105. The rail system 108 comprises a first set of parallel rails no arranged to guide movement of the container handling vehicles 201,301,401 in a first direction X across the top of the frame structure 100, and a second set of parallel rails 111 arranged perpendicular to the first set of rails no to guide movement of the container handling vehicles 201,301,401 in a second direction Y which is perpendicular to the first direction X. Containers 106 stored in the columns 105 are accessed by the container handling vehicles 201,301,401 through access openings 112 in the rail system 108. The container handling vehicles 201,301,401 can move laterally above the storage columns 105, i.e. in a plane which is parallel to the horizontal X-Y plane.

[005] The upright members 102 of the framework structure 100 may be used to guide the storage containers during raising of the containers out from and lowering of the containers into the columns 105. The stacks 107 of containers 106 are typically self-supporting.

[oo6] Each prior art container handling vehicle 201,301,401 comprises a vehicle body 201a, 301a, 401a and first and second sets of wheels 201b, 201c, 301b, 301c, 401b, 401c which enable the lateral movement of the container handling vehicles 201,301,401 in the X direction and in the Y direction, respectively. In Figs. 2, 3 and 4 two wheels in each set are fully visible. The first set of wheels 201b, 301b, 401b is arranged to engage with two adjacent rails of the first set no of rails, and the second set of wheels 201c, 301c, 401c is arranged to engage with two adjacent rails of the second set 111 of rails. At least one of the sets of wheels 201b, 201c, 301b, 301c, 401b, 401c can be lifted and lowered, so that the first set of wheels 201b, 301b, 401b and/or the second set of wheels 201c, 301c, 401c can be engaged with the respective set of rails no, 111 at any one time.

[007] Each prior art container handling vehicle 201,301,401 also comprises a lifting device for vertical transportation of storage containers 106, e.g. raising a storage container 106 from, and lowering a storage container 106 into, a storage column 105. The lifting device comprises one or more gripping / engaging devices which are adapted to engage a storage container 106, and which gripping / engaging devices can be lowered from the vehicle 201,301,401 so that the position of the gripping / engaging devices with respect to the vehicle 201,301,401 can be adjusted in a third direction Z which is orthogonal the first direction X and the second direction Y. Parts of the gripping device of the container handling vehicles 301,401 are shown in Figs. 3 and 4 indicated with reference number 304,404. The gripping device of the container handling device 201 is located within the vehicle body 201a in Fig. 2 and is thus not shown.

[008] Conventionally, and also for the purpose of this application, Z=i identifies the uppermost layer available for storage containers below the rails 110,111, i.e. the layer immediately below the rail system 108, =2 the second layer below the rail system 108, =3 the third layer etc. In the exemplary prior art disclosed in Fig. 1, =8 identifies the lowermost, bottom layer of storage containers. Similarly, X=i...n and Y=i...n identifies the position of each storage column 105 in the horizontal plane. Consequently, as an example, and using the Cartesian coordinate system X, Y, Z indicated in Fig. 1, the storage container identified as 106’ in Fig. 1 can be said to occupy storage position X=i , Y=i, Z=6. The container handling vehicles 201,301,401 can be said to travel in layer Z=o, and each storage column 105 can be identified by its X and Y coordinates. Thus, the storage containers shown in Fig. 1 extending above the rail system 108 are also said to be arranged in layer Z=o.

[009] The storage volume of the framework structure 100 has often been referred to as a grid 104, where the possible storage positions within this grid are referred to as storage cells. Each storage column may be identified by a position in an X- and Y-direction, while each storage cell may be identified by a container number in the X-, Y- and Z-direction.

[0010] Each prior art container handling vehicle 201,301,401 comprises a storage compartment or space for receiving and stowing a storage container 106 when transporting the storage container 106 across the rail system 108. The storage space may comprise a cavity arranged internally within the vehicle body 201a, 401a as shown in Figs. 2 and 4 and as described in e.g. WO2O15/193278A1 and W02019/206487A1, the contents of which are incorporated herein by reference.

[0011] Fig. 3 shows an alternative configuration of a container handling vehicle 301 with a cantilever construction. Such a vehicle is described in detail in e.g. NO317366, the contents of which are also incorporated herein by reference.

[0012] The cavity container handling vehicle 201 shown in Fig. 2 may have a footprint that covers an area with dimensions in the X and Y directions which is generally equal to the lateral extent of a storage column 105, e.g. as is described in WO2O15/193278A1, the contents of which are incorporated herein by reference. The term ‘lateral’ used herein may mean ‘horizontal’.

[0013] Alternatively, the cavity container handling vehicles 401 may have a footprint which is larger than the lateral area defined by a storage column 105 as shown in Fig. 1 and 4, e.g. as is disclosed in W02014/090684A1 or W02019/206487A1.

[0014] The rail system 108 typically comprises rails with grooves in which the wheels of the vehicles run. Alternatively, the rails may comprise upwardly protruding elements, where the wheels of the vehicles comprise flanges to prevent derailing. These grooves and upwardly protruding elements are collectively known as tracks. Each rail may comprise one track, or each rail 110,111 may comprise two parallel tracks. In other rail systems 108, each rail in one direction (e.g. an X direction) may comprise one track and each rail in the other, perpendicular direction (e.g. a Y direction) may comprise two tracks. Each rail 110,111 may also comprise two track members that are fastened together, each track member providing one of a pair of tracks provided by each rail.

[0015] W02018/146304A1, the contents of which are incorporated herein by reference, illustrates a typical configuration of rail system 108 comprising rails and parallel tracks in both X and Y directions.

[0016] In the framework structure 100, a majority of the columns are storage columns 105, i.e. columns 105 where storage containers 106 are stored in stacks 107. In addition to storage columns 105, there are special-purpose columns within the framework structure. In Fig. 1, columns 119 and 120 are such specialpurpose columns used by the container handling vehicles 201,301,401 to drop off and/or pick up storage containers 106 so that they can be transported to an access station (not shown) where the storage containers 106 can be accessed from outside of the framework structure 100 or transferred out of or into the framework structure 100. Within the art, such a location is normally referred to as a ‘port’ and the column in which the port is located may be referred to as a ‘port column’ 119,120. The transportation to the access station may be in any direction, that is horizontal, tilted and/or vertical. For example, the storage containers 106 may be placed in a random or dedicated column 105 within the framework structure 100, then picked up by any container handling vehicle and transported to a port column 119,120 for further transportation to an access station. The transportation from the port to the access station may require movement along various different directions, by means such as delivery vehicles, trolleys or other transportation lines. Note that the term ‘tilted’ means transportation of storage containers 106 having a general transportation orientation somewhere between horizontal and vertical.

[0017] In Fig. 1, the first port column 119 may for example be a dedicated drop-off port column where the container handling vehicles 201,301,401 can drop off storage containers 106 to be transported to an access or a transfer station, and the second port column 120 may be a dedicated pick-up port column where the container handling vehicles 201,301,401 can pick up storage containers 106 that have been transported from an access or a transfer station.

[0018] The access station may typically be a picking or a stocking station where product items are removed from or positioned into the storage containers 106. In a picking or a stocking station, the storage containers 106 are normally not removed from the automated storage and retrieval system 1, but are returned into the framework structure 100 again once accessed. A port can also be used for transferring storage containers to another storage facility (e.g. to another framework structure or to another automated storage and retrieval system), to a transport vehicle (e.g. a train or a lorry), or to a production facility.

[0019] A conveyor system comprising conveyors is normally employed to transport the storage containers between the port columns 119,120 and the access station.

[0020] If the port columns 119,120 and the access station are located at different levels, the conveyor system may comprise a lift device with a vertical component for transporting the storage containers 106 vertically between the port column 119,120 and the access station.

[0021] The conveyor system may be arranged to transfer storage containers 106 between different framework structures, e.g. as is described in W02014/075937A1, the contents of which are incorporated herein by reference.

[0022] When a storage container 106 stored in one of the columns 105 disclosed in Fig. 1 is to be accessed, one of the container handling vehicles 201,301,401 is instructed to retrieve the target storage container 106 from its position and transport it to the drop-off port column 119. This operation involves moving the container handling vehicle 201,301,401 to a location above the storage column 105 in which the target storage container 106 is positioned, retrieving the storage container 106 from the storage column 105 using the container handling vehicle’s 201,301,401 lifting device (not shown), and transporting the storage container 106 to the drop-off port column 119. If the target storage container 106 is located deep within a stack 107, i.e. with one or a plurality of other storage containers 106 positioned above the target storage container 106, the operation also involves temporarily moving the abovepositioned storage containers prior to lifting the target storage container 106 from the storage column 105. This step, which is sometimes referred to as “digging” within the art, may be performed with the same container handling vehicle that is subsequently used for transporting the target storage container to the drop-off port column 119, or with one or a plurality of other cooperating container handling vehicles. Alternatively, or in addition, the automated storage and retrieval system 1 may have container handling vehicles 201,301,401 specifically dedicated to the task of temporarily removing storage containers 106 from a storage column 105. Once the target storage container 106 has been removed from the storage column 105, the temporarily removed storage containers 106 can be repositioned into the original storage column 105. However, the removed storage containers 106 may alternatively be relocated to other storage columns 105.

[0023] When a storage container 106 is to be stored in one of the columns 105, one of the container handling vehicles 201,301,401 is instructed to pick up the storage container 106 from the pick-up port column 120 and transport it to a location above the storage column 105 where it is to be stored. After any storage containers 106 positioned at or above the target position within the stack 107 have been removed, the container handling vehicle 201,301,401 positions the storage container 106 at the desired position. The removed storage containers 106 may then be lowered back into the storage column 105, or relocated to other storage columns 105.

[0024] For monitoring and controlling the automated storage and retrieval system 1, e.g. monitoring and controlling the location of respective storage containers 106 within the framework structure 100, the content of each storage container 106, and the movement of the container handling vehicles 201,301,401 so that a desired storage container 106 can be delivered to the desired location at the desired time without the container handling vehicles 201,301,401 colliding with each other, the automated storage and retrieval system 1 comprises a control system 500 which typically is computerized and which typically comprises a database for keeping track of the storage containers 106.

[0025] If a remotely operated vehicles carries a very heavy storage container, it may tend to tip over during an emergency braking process. A measure to avoid this is shown in WO 2022/112166 Al, which discloses a remotely operated vehicle for handling a storage container, wherein the vehicle comprises a mass balancing system for purposely displacing a balance weight in order to improve stability of the remotely operated vehicle and avoid, inter alia, tipping up of the vehicle.

[0026] It is an object of the invention to provide an alternative solution for preventing a tipping over or other instabilities of a remotely operated vehicle.

SUMMARY OF THE INVENTION

[0027] This summary is provided to introduce in simplified form a selection of concepts that are further described herein. The summary is not intended to identify key or essential features of the invention. [0028] The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention. The present invention is also set forth and characterized in the independent clauses, while the dependent clauses describe other characteristics of the invention.

[0029] In one aspect, the invention is related to a remotely operated vehicle for handling a storage container, said remotely operated vehicle arranged to work on a rail system of an automated storage and retrieval system, said rail system comprising a first set of parallel rails and a second set of parallel rails arranged perpendicular to the first set of parallel rails, said remotely operated vehicle comprising a first set of wheels being arranged to engage with two adjacent rails of the first set of rails, and a second set of wheels being arranged to engage with two adjacent rails of the second set of rails, said vehicle further comprising at least one motor and a vehicle control unit, the vehicle control unit configured to operate the at least one motor, the at least one motor being operatively coupled with the wheels to move the vehicle on the rail system, and the vehicle control unit being configured to limit at least one of a maximum travel speed and a maximum acceleration of the vehicle in at least one direction depending on the weight of a storage container carried by the vehicle, such that a tilting of the vehicle and/or wheel skidding is prevented.

[0030] The remotely operated vehicle is preferably controlled by a central control system mentioned further above. It may, for example, receive commands from the control system to drive from a starting point, e.g. a first grid cell, to an end point, e.g. a second grid cell, and to retrieve or place a storage container at the starting point and/or the end point. The control system is preferably capable of planning the motion paths and actions of a plurality of remotely operated vehicles depending on a task to be accomplished by the storage and retrieval system. The control system then sends respective commands to the vehicles.

[0031] Each of the vehicles may be configured to receive and implement the commands. In addition to moving forward, backward, or laterally, the vehicles are also capable of stopping at a desired location, retrieving a storage container from a storage column, carrying a storage container, and storing a storage container in a storage column. Furthermore, the vehicles may be adapted to conduct an emergency braking process upon receiving an associated command. It is conceivable that a certain braking distance is defined, along which the moving vehicle shall come to a full stop. [0032] When carrying a storage container, the vehicle and the storage container form a combined unit with a combined center of gravity. Depending on the design of the vehicle, the carrying position of the storage container, and the weight of the storage container, the combined center of gravity may shift in a vertical and/or horizontal position relative to the center of gravity of the vehicle alone. Consequently, the dynamic behavior of the vehicle that carries a storage container differs from that of the vehicle alone. If the vehicle carries a heavy storage container underneath a cantilever structure extending into a forward direction, the vehicle may have a tendency to tip over if it conducts an emergency braking from a motion along the forward direction.

[0033] The maximum travel speed may be reduced with increasing weight of the storage container that is carried by the vehicle. The vehicle that carries a heavy storage container will thus travel at a reduced speed in at least one direction. Thus, it does not need to decelerate as quickly as a vehicle carrying a lighter storage container or no storage container at all to come to a full stop in the defined braking distance. Hence, when reducing the maximum travel speed in at least one direction, the inertial force acting onto the combined unit of storage container and vehicle resulting from an emergency braking process when traveling in the respective direction can be reduced. The maximum travel speed of the vehicle can be chosen in a way that a tilting of the vehicle can be avoided during an emergency braking process.

[0034] Similarly, the acceleration in at least one direction may be limited depending on the weight of the storage container that is carried by the vehicle. If the vehicle carries a heavy storage container underneath a cantilever structure extending into a forward direction, the vehicle may have a tendency to tip over if it quickly accelerates into a rearward direction. Thus, by limiting the acceleration in this direction, a tilting of the vehicle carrying the storage container can be prevented.

[0035] Also, in analogy to the above, travel speed and acceleration in lateral directions may be limited depending on the weight of the storage container to prevent a tilting of the vehicle.

[0036] In a similar way, a wheel skidding may be prevented. A wheel skidding may be experienced before a tilting would occur, when driving wheels are not sufficiently pressed onto the respective rails, as will be explained in more detail in the following. [0037] It is conceivable that the control system, which controls the operation of all remotely operated vehicles, has knowledge about the weight of each storage container stored in the storage and retrieval system. Hence, the weight of a storage container to be carried by a remotely operated vehicle may be already known to the control system. The control system may be capable of calculating maximum travel speed values and/or maximum acceleration values for each path segment of the vehicles according to the above. Also, these values may be different for different travel directions. The respective values may be transmitted to the individual vehicles and each of the vehicles may follow these values through the respective vehicle control unit. The calculation of the values maybe integrated into a path planning algorithm in the control system. Using different travel speeds and/or accelerations has an effect on the automated storage and retrieval system, which is to be considered in the path planning and the meshing of the motion paths of different vehicles.

[0038] As an alternative and/or additionally thereto, the vehicle control unit of each of the vehicles may be configured to calculate the maximum values depending on the weight of the storage container that is carried by the respective vehicle. The vehicle control unit may then transfer these values to the control system of the storage and retrieval system, such that it is capable of retrieving exact information about the expected motion of all remotely operated vehicles.

[0039] Thus, the functionality described herein may be provided by the control system of the automated storage and retrieval system, by the respective vehicle control units of the remotely controlled vehicles operating in the automated storage and retrieval system. Also, a combination of both is conceivable, e.g. when operating mixed types of remotely-operated vehicles on the automated storage and retrieval system.

[0040] The at least one motor of the vehicle as mentioned above is used for driving the vehicle and maybe realized through different embodiments. For example, it may comprise one or two central motors for selectively driving the wheels of the first set and the second set. However, the at least one motor may comprise a set of motors, such as in-wheel motors included into the wheels of the first and second set of wheels. More torque might be applied to one pair compared to the other to compensate for movement in where the combined center of gravity acts through the footprint of the wheels by adjusting the forces involved. [0041] Resultantly, the vehicle is capable of conducting a dynamic control of the vehicle speed and/or acceleration depending on the weight of the storage container carried by the vehicle.

[0042] In particular when limiting the maximum acceleration, the weight of the remotely operated vehicle may be reduced by an appropriate amount, while tilting and/ or wheel skidding may still be avoided. A remotely operated vehicle with a reduced weight may lead to a reduced power consumption, which in turn may lead to a longer runtime on battery, if the size of the battery remains the same. However, with a reduced weight and reduced travel speed and/or acceleration, the size of the battery may be reduced, while the same runtime on battery may be achieved. This would lead to a reduced manufacturing and maintenance costs.

[0043] It is conceivable that the vehicle comprises at least one brake, which is coupled with the vehicle control unit. The vehicle control unit may monitor the travel speed of the vehicle and may operate the brake to limit the travel speed if it is exceeded. In this case, a certain speed limiting brake force shall not be exceeded.

[0044] The vehicle may be a cantilever type vehicle for lifting and carrying a storage container on a side of the vehicle below a cantilever structure of the vehicle. The vehicle may thus have a main vehicle body comprising or being attached to a chassis, which may carry the wheel sets at opposite sides of the chassis. A lifting frame for releasably connecting to a storage container may be coupled with the cantilever structure, which extends over the footprint of the chassis to one side. The lifting frame may be coupled with a lifting device through four lifting bands, wherein each of the lifting bands is connected to one of four corner regions of the lifting frame. By this design, the storage container is carried beyond the footprint of the wheels of the vehicle. If the storage container is heavy, the combined unit formed by the vehicle and the storage container is horizontally shifted towards the cantilever structure.

[0045] It is to be understood that other types of remotely controlled vehicles are conceivable, such as substantially symmetric vehicles having a receiving space inside of a vehicle body configured to receive the storage container to be carried.

[0046] The vehicle may comprise at least one weight sensor configured to measure a weight of a storage container carried by the vehicle, wherein the at least one weight sensor may be coupled with the vehicle control unit. The at least one weight sensor may be integrated into the lifting device that is coupled with lifting bands. The at least one weight sensor may be integrated into gripping devices arranged on the lifting frame and engageable with storage containers. Also, the at least one weight sensor may be integrated into a connecting part between the lifting frame and a lifting band. The at least one weight sensor may also comprise a plurality of weight sensors, e.g. one for every corner of the lifting frame. The at least one weight sensor may be configured to measure a downwardly directed force acting onto the lifting frame or a lifting band. Additionally, and/or as an alternative, the at least one weight sensor maybe realized by an algorithm, which is configured to receive information about the power consumption of a lifting motor that is configured to lift the lifting frame. The power consumption may either be a measurable electric power, or it may be calculated from a measured torque on a drive shaft of the respective lifting motor and the angular velocity of the shaft. Thus, the at least one weight sensor may comprise a torque sensor attached to the drive shaft of the respective lifting motor. Altogether, the at least one weight sensor is provided for measuring the weight of a storage container carried by the vehicle to be able to limit the maximum speed and/or acceleration of the vehicle depending on the weight of the storage container.

[0047] The vehicle control unit may be configured to limit the maximum travel speed and/or acceleration of the vehicle depending on the position of the combined center of gravity of the vehicle carrying a storage container, which position depends on the weight of the storage container. By knowing the position of the combined center of gravity, a tilting point of the vehicle carrying the storage container can be calculated. During an emergency braking process, the tilting point is reached if the rearward wheels still engage the rails, but do not carry any weight anymore. At the same time the inertial force in a forward direction and the weight force into a downward direction act onto the combined center of gravity and create a moment equilibrium on the forward wheels. As the inertial force onto the combined center of gravity is the product of combined mass and deceleration, the weight force on the combined center of gravity is the product of combined mass and gravitational acceleration. Depending on the actual position of the combined center of gravity, a vertical distance from the combined center of gravity and a contact point of a forward wheel is created, which is the lever arm for the moment created by the inertial force. A horizontal distance from the combined center of gravity to the contact point of a forward wheel is created, which is the lever arm for the moment created by the weight force. If both moments are in equilibrium and if the rear wheels do not carry any weight anymore, the vehicle just does not tip over. Every increase in deceleration would lead to a tilting motion of the vehicle. In analogy to this, a tilting point for an acceleration motion can be calculated, in which it is assumed that (depending on the direction of the motion) one wheel pair engages the rails but does not carry any weight anymore, while the weight force and the inertial force resulting from the acceleration form an equilibrium. This also applies for lateral motions. Thus, by knowing the position of the combined center of gravity, the tilting point for a planned motion of the vehicle can be calculated, which determines the maximum absolute value for the acceleration or deceleration of the vehicle to prevent tilting. A determination of the maximum travel speed and/or the maximum acceleration maybe conducted by the control system and/or the vehicle control unit.

[0048] If wheels that are driving the vehicle engage the rails, but are not sufficiently pressed onto the rails, a wheel skidding may occur. This means that the wheels may slip or spin and do not provide a sufficient acceleration or deceleration. This may occur if the vehicle carries a rather heavy storage container, which results in a position of the combined center of gravity that in some load cases leads to reducing the load on one pair of the wheels. If this particular pair is the only driven pair of wheels, a skidding may occur. In this case, a skidding point may be reached before reaching the tilting point explained above and may depend on the friction coefficient of the wheel/rail combination and which of the wheels are driven. The reduction of the vertical load onto the driven wheels at a certain acceleration in a certain direction may reduce the friction and thus the achievable limit of driving force. However, if another pair of wheels is driven, e.g. the pair of wheels facing the storage container in a cantilever-type vehicle, a skidding may not be expected. In such a case, the pressing force onto the driving wheels increases with the weight inside the storage container, which leads to a higher potential for acceleration.

[0049] A certain safety factor may be included into such a calculation, such that a tolerable absolute value for acceleration or deceleration may be slightly lower than the calculated maximum value. This may be, for example, be in a range of 60 to 90% and preferably of 70 to 80%. If the tolerable absolute value for deceleration is known, the maximum travel speed can be calculated from the tolerable deceleration value and a defined braking distance. [0050] The vehicle control unit may be configured to determine the position of the combined center of gravity based on the measured weight of the storage container carried by the vehicle. The position of the storage container relative to the vehicle may be determined by the position of the lifting frame when carrying the storage container. It may be assumed that the lifting frame is in an uppermost position when the vehicle moves on the grid above the storage columns. It may be assumed that the center of gravity and the overall dimensions of the vehicle is known. It may also be assumed that the position of the center of gravity of the storage container is known or can at least be estimated. However, to reflect uncertainties about the position of the center of gravity of the storage container, it may be assumed that the center of gravity of the storage container is in a vertical center of the storage container, or slightly further to the top of the storage container. It may be assumed that the center of gravity of the storage container may be arranged in a worst position with regard to tilting and/or skidding, in a horizontal direction. For example, the center of gravity of the storage container may be placed 2/3 from a back wall of the storage container, i.e. the wall directed to the vehicle, which could define a worst-case scenario for the tilting. If the center of gravity is about 1/3 from the back wall, this could define a skidding, i.e. a lowest potential for acceleration. The vertical position of the center of gravity of the storage container affects the dimension of the lever arm for the moment introduced by the inertial force around the respective wheels, as explained above. The horizontal position of the center of gravity of the storage container affects the dimension of the lever arm for the moment introduced by the gravitational force around the respective wheels. The vehicle may include the at least one weight sensor mentioned above. This would allow to calculate the position of the combined center of gravity under consideration of a known, preferably predefined center of gravity of the vehicle alone. The position of the combined center of gravity may be calculated after picking up a storage container or after placing a storage container. This may be done by calculating the sum of the products of the individual coordinates of the centers of gravity and the respective individual weight and divide the sum by the total mass:

wherein cog_c are the vectorial coordinates of the combined center of gravity. The term cogt refers to the individual centers of gravity, i.e. the vehicle center of gravity and the storage container center of gravity. In analogy, mi are the individual masses, i.e. the mass of the vehicle and the mass of the storage container. The coordinates may be defined in a vehicle coordinate system. [0051] It is assumed that the center of gravity of the storage container remains substantially constant. However, if the goods are able to move inside the storage container, this may temporarily change the center of gravity of the storage container and thus, the combined center of gravity.

[0052] As an alternative and/or additionally thereto, instead of the calculation of the combined center of gravity, an estimation of a maximum travel speed and/or a maximum acceleration in at least one direction maybe conducted. For example, the vehicle control unit and/or the control system may comprise lookup tables, in which storage container weights and maximum travel speeds and/or accelerations in at least one direction are linked.

[0053] The vehicle control unit may be configured to receive weight information for the storage container carried by the vehicle from externally, and to determine the position of the combined center of gravity based on the received weight information. The storage and retrieval system may already have information about the respective storage container stored in the grid, including information about the weight. This information may be transferred to the respective vehicle to be considered when determining the position of the combined center of gravity. The weight information may include the mass of the storage container including the goods contained therein. It also may include information about a fill level, which allows to estimate the center of gravity of the storage container. It is conceivable that the weight information also include other details, like the height of the storage container, and/or a parameter to take account of uneven loading or shift in load. The weight information may comprise an active parameter that starts with a fully loaded or empty container that is adjusted over time as items are removed from or placed into the container over time.

[0054] It is conceivable that the vehicle control unit and/or the control system to comprise geometric information of the vehicle, such as the position of the wheels in relation to the storage container carried by the vehicle. This allows to determine or estimate a tilting point of the vehicle that carries a storage container.

[0055] The vehicle control unit may be configured to limit the maximum travel speed in a first direction of travel, wherein the first direction of travel is defined by the orientation of the container carried by the vehicle relative to a body of the vehicle. The first direction of travel may be a forward direction of a cantilever type vehicle, which carries the storage container underneath a cantilever structure that extends in a forward direction of the vehicle.

[0056] The vehicle control unit may be configured to limit a maximum acceleration in a second direction of travel, wherein the second direction of travel is opposite to the first direction. A strong acceleration in the second direction of travel may have the same effect as a strong deceleration in the first direction.

[0057] Further functionalities may be provided by the vehicle to prevent a tilting. For example, lifting up a heavy storage container maybe limited in speed, in order to reduce the inertial force acting onto the vehicle during lifting. The vehicle maybe configured to start to lower and/or finish raising a storage containers before they come to a halt and/ or start moving off, depending on the actual travel direction, to avoid a tilting.

[0058] It may be conceivable if the vehicle recognizes, which wheels are in contact with the rails. For example, weight sensors maybe integrated into wheel supports, coupled with the vehicle control unit. If a weight measured by a weight sensor is lower than expected, wheels leaving the rails can be concluded. If it is measured that wheels are about to leave the rails, a tilting and/or wheel skidding maybe detected. The vehicle may then actively reduce the acceleration and/or travel speed and/or re-determine the limits.

[0059] In a second aspect, the invention concerns a method for operating a vehicle for handling a storage container, said vehicle working on a rail system of an automated storage and retrieval system, said rail system comprising a first set of parallel rails and a second set of parallel rails arranged perpendicular to the first set of parallel rails, said vehicle comprising a first set of wheels being arranged to engage with two adjacent rails of the first set of rails, and a second set of wheels being arranged to engage with two adjacent rails of the second set of rails, said vehicle further comprising at least one motor, and a vehicle control unit, the method comprising: operating the at least one motor operatively coupled with the wheels to move the vehicle on the rail system, and limiting a maximum travel speed of the vehicle depending on the weight of a storage container carried by the vehicle, through the vehicle control unit.

[0060] The method may comprise measuring a weight of a storage container carried by the vehicle through at least one weight sensor connected to the vehicle control unit. [0061] Limiting the maximum travel speed of the vehicle may be conducted depending on the position of the combined center of gravity of the vehicle carrying a storage container, which position depends on the weight of the storage container.

[0062] The method may comprise determining the position of the combined center of gravity based on the measured weight of the storage container carried by the vehicle through the vehicle control unit.

[0063] The method may comprise receiving weight information of the storage container carried by the vehicle from externally, and determining the position of the combined center of gravity based on the received weight information through the vehicle control unit.

[0064] Limiting the maximum travel speed may comprise limiting the maximum travel speed in a first direction of travel, wherein the first direction of travel is defined by the orientation of the container carried by the vehicle relative to a body of the vehicle.

[0065] The method may comprise limiting a maximum acceleration in a second direction of travel through the vehicle control unit, wherein the second direction of travel is opposite to the first direction.

[0066] In a third aspect the invention is directed to an automated storage and retrieval system, comprising a framework structure having 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 and second sets of rails form a grid pattern in the horizontal plane comprising a plurality of adjacent grid cells, each comprising a grid opening defined by a pair of neighboring rails of the first set of rails and a pair of neighboring rails of the second set of rails; and at least one remotely operated vehicle for handling a storage container according to the above being configured to move on the rail system above the storage columns.

[0067] The methods described herein may be implemented using computerexecutable instructions. Accordingly, in a fourth aspect the invention provides a computer program such as a computer program on a carrier medium (e.g. a non- transitory carrier medium) comprising computer-executable instructions which, when executed by at least one processor, cause the methods described herein to be performed or implemented. Framed alternatively, in the fourth aspect , the invention is directed to a computer program product for a control unit, the computer program product comprising instructions that when performed on the control unit performs the described methods.

BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Following drawings are appended to facilitate the understanding of the invention. The drawings show embodiments of the invention, which will now be described by way of example only, where:

[0069] Fig. 1 is a perspective view of a framework structure of a prior art automated storage and retrieval system.

[0070] Fig. 2 is a perspective view of a prior art container handling vehicle having an internally arranged cavity for carrying storage containers therein.

[0071] Fig. 3 is a perspective view of a prior art container handling vehicle having a cantilever for carrying storage containers underneath.

[0072] Fig. 4 is a perspective view, seen from below, of a prior art container handling vehicle having an internally arranged cavity for carrying storage containers therein.

[0073] Figs. 5 and 6 show a cantilever-type vehicle traveling forward or backward, wherein relevant forces occurring during a braking process are shown.

[0074] Fig. 7 shows the cantilever-type vehicle traveling laterally, wherein relevant forces occurring during a braking process are shown.

[0075] Fig. 8 shows a detail of a lifting frame with a storage container and weight sensors.

[0076] Fig. 9 shows a block-oriented diagram of a vehicle.

[0077] Fig. 10 shows a block-oriented diagram of the method.

[0078] Fig. 11 shows a perspective view of an automated storage and retrieval system. DETAILED DESCRIPTION OF THE INVENTION

[0079] In overview, a remotely operated vehicle (600) for handling a storage container (106) is provided. The remotely operated vehicle (600) comprises wheels, at least one motor (615) and a vehicle control unit (604). The vehicle control unit (604) is configured to operate the at least one motor (615), the at least one motor (615) being operatively coupled with the wheels to move the vehicle (600). The vehicle control unit (604) is configured to limit at least one of a maximum travel speed and a maximum acceleration of the vehicle (600) in at least one direction depending on the weight of a storage container (106) carried by the vehicle (600), such that a tilting of the vehicle (600) and/or wheel skidding is prevented. The remotely operated vehicle is for use with an automated storage and retrieval system. The system may comprise a rail system for the wheels of the vehicle to engage with.

[0080] In the following, embodiments of the invention will be discussed in more detail 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.

[0081] The framework structure 100 of the automated storage and retrieval system 1 is constructed in a similar manner to the prior art framework structure 100 described above in connection with Figs. 1-3. That is, the framework structure 100 comprises a number of upright members 102, and comprises a first, upper rail system 108 extending in the X direction and Y direction.

[0082] The framework structure 100 further comprises storage compartments in the form of storage columns 105 provided between the members 102 wherein storage containers 106 are stackable in stacks 107 within the storage columns 105.

[0083] The framework structure 100 can be of any size. In particular it is understood that the framework structure can be considerably wider and/or longer and/or deeper than disclosed in Fig. 1. For example, the framework structure 100 may have a horizontal extent of more than 700x700 columns and a storage depth of more than twelve containers.

[0084] One embodiment of the automated storage and retrieval system according to the invention will now be discussed in more detail with reference to Figs. 5 to 9. [0085] Fig. 5 shows a remotely controlled vehicle 600 having a vehicle body 601, and a cantilever structure 605 extending away from one side of the vehicle body 601. A lifting frame 606 for lifting storage containers 106 is provided and can be moved vertically relative to the cantilever structure 605. In this illustration, the lifting frame 606 carries a storage container 106, which maybe lifted from a storage column of a storage and retrieval system shown in Fig. 1.

[0086] For the following detailed explanation of core aspects of the invention it is referred to the description of the rail system 108 further above. As described, the rail system 108 may comprise rails with grooves in which the wheels of the vehicle 600 run. Alternatively, the rails may comprise upwardly protruding elements, where the wheels of the vehicle 600 comprise flanges to prevent derailing. These grooves and upwardly protruding elements are referred to as tracks. Each rail may comprise one track, or each rail no, 111 may comprise two parallel tracks. As also mentioned before, in another rail system 108 each rail in one direction (e.g. an X direction) may comprise one track and each rail in the other, perpendicular direction (e.g. a Y direction) may comprise two tracks. Each rail no, 111 may also comprise two track members that are fastened together, each track member providing one of a pair of tracks provided by each rail.

[0087] As explained above, the vehicle 600 comprises a first set of wheels 301b to move vehicle 600 in a first direction, which is indicated with an X. The vehicle 600 is moving along the X direction, such that the first set of wheels 301b engage the rails 110, i.e. they run in grooves or upwardly protruding elements, which run along the X direction. In this motion direction, a pair of wheels 608 can be considered front wheels 608, while another pair of wheels 607 can be considered rear wheels 607. A second set of wheels 301c is provided for moving the vehicle 600 in a second direction, which is indicated with an Y. In this illustration, the second set of wheels 301c is deactivated and do not engage with the perpendicular rails 111. The lifting frame 606 is held by lifting bands, which are not shown herein, to be moved in a Z direction.

[0088] The empty vehicle 600, i.e. the vehicle 600 without the storage container 106, has a vehicle center of gravity 602, which is exemplarily shown to be substantially in the center of the vehicle body 601. Internal components of the vehicle 600 may be arranged in the vehicle body 601 in a way that the vehicle center of gravity 602 is near a center of the vehicle body 601. When carrying the storage container 106, a combined unit consisting of the vehicle 600 and the storage container 106 is formed. This results in a combined center of gravity 603, which is shifted at least in the X direction towards the storage container 106. It is conceivable that the combined center of gravity 603 also shifts in a Z direction upwards or downwards. This depends on the weight and distribution of the goods stored in the storage container 106 and the empty weight of the storage container 106.

[0089] The vehicle 600 travels in the X direction with a certain traveling speed vt, wherein the storage container 106 is in front of the vehicle body 601 in the motion direction. When conducting an emergency braking process, the vehicle 600 carrying the storage container 106 is supposed to come to a full stop during a braking distance sb, such that it does not move on the rails no anymore. It is desired, that the vehicle 600 does not tilt on the rails no during such an emergency braking process. A tilting can occur, if the rear wheels 607 leave the rails 110, i.e. move away from the grooves or upwardly protruding elements, and do not carry any weight of the vehicle 600 anymore, while contact points 609 between the front wheels 608 and the rails 110 define a tilting axis for the vehicle 600 around which the vehicle 600 tilts in a mathematical positive way, i.e. counter-clockwise.

[0090] To find the tilting point, where the rear wheels 607 do not carry any weight anymore and start to leave the rails no, following calculation under consideration of a simplified physical model may be made. Additional dynamic characteristics of the vehicle 600 maybe considered by the skilled person. Upon braking, an initial force Ft acts through the combined center of gravity 603 in the forward direction. Ft is calculated as the product of the combined mass m_c of the vehicle 600 and the storage container 106 and the absolute value of the deceleration ad. The deceleration ad depends on the action of the brake. It is conceivable that a maximum value of a deceleration may be slightly above 1 m/s², for example between 1 m/s² and 2 m/s². At the same time, a weight force W acts through the combined center of gravity 603 in the Z direction, wherein the weight force W is the product of the combined mass m_c and the gravitational acceleration g. It is assumed that a vertical force F_r acting onto the rear wheels 607 is zero, while the vertical force Ff acting onto the contact points 609 between the front wheels 608 and the rails no equals the weight force Win the tilting point. This is the case when the moments resulting from Ft and W about the tilting axis are in equilibrium:

m_c ■ a_d - s_t = W ■ s_w wherein st is the vertical distance from the combined center of gravity of the contact points 609 and siv is the horizontal distance from the combined center of gravity 603 to the contact points 609. From this, a maximum deceleration ad, max can be determined:

_ W - s_w a^d’^max ~ m_c - _Si

[0091] The vehicle 600 will tilt if the deceleration exceeds the maximum deceleration ad, max. To ensure that the vehicle 600 does not need to exceed the maximum deceleration ad, max, the vehicle 600 must be able to stop in the defined braking distance sb, which defines the longest traveling distance of the vehicle 600 from the beginning of the braking process until coming to a full stop. Assuming a constant deceleration ad during the braking distance, and assuming the use of the full braking distance sb, a maximum initial travel speed vt,max before starting to brake can be calculated as following:

[0092] Thus, if the cantilever-style vehicle 600 travels in the X direction with a speed vt that equals vt,max at a maximum, the vehicle 600 will not tilt during an emergency braking when using the full available braking distance. The determination of the maximum travel speed vt,max takes the weight of the storage container 106 into consideration. In particular, the location of the combined center of gravity determines the maximum allowed deceleration and thus the maximum travel speed when entering an emergency braking process.

[0093] In analogy to this, the absolute value of the maximum acceleration for a backward motion, i.e. into the exemplarily illustrated -X direction and having the vehicle body 601 forward of the cantilever structure 605, the absolute value of the maximum acceleration a max equals the absolute value of the abovedetermined maximum deceleration to avoid a tilting of the vehicle 600. [0094] As illustrated in Fig. 6, an emergency braking process from a motion in the backward direction, i.e. into the exemplarily illustrated -X direction and having the vehicle body 6oi forward of the cantilever structure 605, may not be limited to the same maximum deceleration ad, max with the exemplary combined center of gravity 603 as shown. A tilting of the vehicle 600 would only occur, if the front wheels 608 leave the rails no and do not carry any weight of the vehicle 600 anymore. This is the case, when the moments resulting from Ft and W about the tilting axis, which in this case is determined by contact points 610 of the rear wheels 607 and the rails no, are in equilibrium and when the force Ff on the front wheels is zero. Assuming that the combined center of gravity is shifted towards the cantilever structure 605, the relevant lever arm, which is indicated by s_wb in Fig. 6, for the weight force W around the tilting axis is clearly greater than the lever arm s_w from Fig. 5. Thus, a tilting of the vehicle 600 would require a much higher inertia force, i.e. a deceleration much higher than ad, max above.

[0095] Given these two examples shown in Figs. 5 and 6, the skilled person will be able to determine the maximum travel velocity vt and/or the maximum deceleration ad, max and/or the maximum acceleration a_max for preventing a tilting of the vehicle 600 in any direction with any location of the combined center of gravity 603.

[0096] This is also the case for a lateral motion, as illustrated in Fig. 7, where a front view of the vehicle 600 is shown. The combined center of gravity 603 maybe shifted upwards relative to the vehicle center of gravity 602. It is assumed that the vehicle 600 drives in the -Y direction, i.e. to the right-hand side in Fig. 7, with the velocity vt. For this, the second set of wheels 301c is used and the wheels to the right-hand side in Fig. 7 are named “left wheels” 611, as they are on the left-hand side of the vehicle 600 when viewing from the vehicle body 601 to the cantilever structure 605. In analogy to this, the wheels on the left-hand side of Fig. 7 are named “right wheels” 612. The vehicle 600 tilts during an emergency braking process with a deceleration adi when the right wheels 612 leave the rails 111, such that the left wheels 611 carry the whole weight force W. At the tilting point, the moments about a tilting axis determined by contact points 613 between the left wheels 611 and the rails 111 are in equilibrium:

wherein si is again the vertical distance from the combined center of gravity 603 to the contact points 613, which is the same as to the contact points 609. The term swi is the horizontal distance from the combined center of gravity 603 to the contact points 613. From this, a maximum lateral deceleration adi,max can be determined in analogy to the explanations of Fig. 5:

_ W ■ s_Wi a_di,_max ~ _mc . _s.

[0097] The same applies to the motion in the opposite lateral direction. If the combined center of gravity is not arranged in the center of the combined unit of the vehicle 600 and the storage container 106 in the Y direction this is considered in the determination of the parameter swi.

[0098] If the exact location of the combined center of gravity 603 is not known, it maybe estimated. For this, the weight of the storage container 106 and the kind of goods inside the storage container 106 maybe used to determine the weight distribution and/or a fill level. The determination or estimation of the combined center of gravity 603 maybe done by the vehicle control unit 604 and/or the control system 500. Also, the maximum travel speed, the maximum absolute value of deceleration and/or of acceleration maybe determined by the vehicle control unit 604 and/or of the control system 500.

[0099] Wheel skidding maybe prevented similarly. It is again referred to Fig. 5. If the front wheels 608 are driving the vehicle 600, the load onto the front wheels 608 increases with increasing weight of the storage container 106, which counteracts skidding.

[00100] However, if it is assumed that the rear wheels 607 are driving the vehicle 600, this maybe different. The rear wheels 607 always require a sufficient friction on the rails no to drive the vehicle 600. A driving force that will accelerate the vehicle 600 is the product of the force Fr on the rear wheels 607 and a friction coefficient u. The higher the acceleration into the rearward direction is, i.e. into the right-hand side of Fig. 5, the lower the load onto the rear wheels 607 will be. This means that with higher acceleration the lower the friction between the rear wheels 607 and the rails no will be, which may in some cases with very heavy storage containers 106 may result in a wheel skidding. In a skidding point, the moments generated by the vertical forces Ff onto the front wheels 608 and by the vertical forces Fr onto the rear wheels 607 as well as the inertial force Ft resulting from the acceleration form an equilibrium, wherein as a further condition the force Fr onto the rear wheels is at the minimum to provide a sufficient friction:

F_t - s_t + F_r - s = W ■ s_w wherein s is the horizontal distance between the contact point 609 of the front wheels 608 and a contact point between the rear wheels 607 and the rails no.

[00101] For achieving an acceleration a_s of the vehicle 600, at which a skidding would begin, a force F_s acts onto the combined center of gravity 603 in the opposite direction to Ft and - in this example - is provided by the rear wheels 607. According to Coulombs Law, the force F_s equals the product of the friction coefficient zz and the vertical force Fr onto the rear wheels 607. This leads to a required minimum vertical force Fr onto the rear wheels:

F_s = F ■ Fr m_c ■ a_s = /z ■ F_r m_c ■ a_s F_r = -

F

[00102] Thus, the skidding point is reached under following condition:

Fi - si + F_r - s = W ■ s_w

[00103] Hence, in the case of the rear wheels 607 driving the vehicle, the acceleration as should not be exceeded for this example and this motion direction to avoid skidding. However, if all wheels 607 and 608 are driven or if only the front wheels 608 are driven, or if another motion direction is intended, the skilled person will be able to find a suitable acceleration limit for avoiding skidding at the respective load case according to the example above.

[00104] Fig. 8 shows an exemplary embodiment of the lifting frame 606, to which four lifting bands 404a are coupled. Between the lifting bands 404a and the lifting frame 606, weight sensors 614a, 614b, 614c and 6i4d are provided. These are configured to measure the force acting between the respective lifting band 404a and the lifting frame 606, i.e. a partial weight of the lifting frame 606 and the storage container 106 held by it. Consequently, the vehicle 600 is capable of measuring the weight of the storage container 106. By using four weight sensors 404a at four corners of the lifting frame 606, a horizontal distribution of the weight of the storage container 106 may be determined. This may allow to adjust the determination of the deceleration, acceleration and/or travel speed, e.g. if it is determined that the storage container 106 carries a heavy item in a forward location, which leads to shifting the combined center of gravity more forward.

[00105] The weight sensors 6i4a-6i4d are coupled with the vehicle control unit 604, which is configured to receive signals representing the weight of the storage container 106 and to process the weight to provide the above-mentioned functions.

[00106] Fig. 9 shows a schematic, block-oriented view of the vehicle 600. It exemplarily comprises at least one motor 615 and the vehicle control unit 604 that is configured to operate the at least one motor 615. The at least one motor 615 is operatively coupled with the wheels 607, 608, 611, 612 shown further above to move the vehicle 600 on the rail system 108. The vehicle control unit 604 is configured to limit at least one of a maximum travel speed and a maximum acceleration of the vehicle 600 in at least one direction depending on the weight of a storage container 106 carried by the vehicle 600, such that a tilting of the vehicle 600 is prevented. For powering the at least one motor 615, an energy storage O maybe provided, such as a battery. The vehicle 600 may comprise at least one weight sensor 614, i.e. 614a, 614b, 614c, 6i4d, mentioned further above.

[00107] Fig. 10 shows a block-oriented illustration of a method for operating a vehicle 600 for handling a storage container 106. The method may comprise operating 617 the at least one motor 615 operatively coupled with the wheels 607, 608, 611, 612 to move the vehicle 600 on the rail system 108, and limiting 618 at least one of a maximum travel speed and a maximum acceleration of the vehicle 600 depending on the weight of a storage container 106 carried by the vehicle 600, through the vehicle control unit 604. This may comprise measuring a weight of a storage container 106 carried by the vehicle 600 through at least one weight sensor 614 connected to the vehicle control unit 604.

[00108] Limiting 618 the maximum travel speed and/or the acceleration of the vehicle may be conducted depending on the position of the combined center of gravity of the vehicle 600 carrying a storage container 106, which position depends on the weight of the storage container 106. Thus, in an exemplary embodiment, the method comprises determining 620 the position of the center of gravity based on the measured weight of the storage container 106 carried by the vehicle 600 through the vehicle control unit 604. This may include receiving 621 weight information of the storage container 106 carried by the vehicle 600 from externally. The limiting 618 can be done in all directions, depending on a tendency to tilting as explained above.

[00109] Fig. 11 shows an automated storage and retrieval system 700 with a framework structure 100, on which the vehicle 600 as described above operates. The framework structure 100 corresponds to the framework structure 100 as explained with Fig. 1. It comprises upright members 102 and a storage volume comprising storage columns 105 arranged in rows between the upright members 102. In these storage columns 105 storage containers 106 are stacked one on top of one another to form stacks 107. The members 102 may typically be made of metal, e.g. extruded aluminum profiles.

[00110] The framework structure 100 of the automated storage and retrieval system 1 comprises the rail system 108 arranged across the top of framework structure 100, on which rail system 108 a plurality of container handling vehicles 600 according to the invention and common container handling vehicles may be operated to raise storage containers 106 from, and lower storage containers 106 into, the storage columns 105, and also to transport the storage containers 106 above the storage columns 105. As explained previously, the rail system 108 comprises a first set of parallel rails no arranged to guide movement of the container handling vehicles 600 in the first direction X across the top of the frame structure 100, and a second set of parallel rails 111 arranged perpendicular to the first set of rails no to guide movement of the container handling vehicles 600 in the second direction Y which is perpendicular to the first direction X. Containers 106 stored in the columns 105 are accessed by the container handling vehicles 600 through access openings 112 in the rail system 108. The container handling vehicles 600 can move laterally above the storage columns 105, i.e. in a plane which is parallel to the horizontal X-Y plane.

[00111] The upright members 102 of the framework structure 100 may be used to guide the storage containers during raising of the containers out from and lowering of the containers into the columns 105. The stacks 107 of containers 106 are typically self-supporting. [ooii2] In the preceding description, various aspects of the delivery vehicle and the automated storage and retrieval system according to the invention have been described with reference to the illustrative embodiment. For purposes of explanation, specific numbers, systems and configurations were set forth in order to provide a thorough understanding of the system and its workings. 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, which are apparent to persons skilled in the art to which the disclosed subject matter pertains, are deemed to lie within the scope of the present invention.

LIST OF REFERENCE NUMBERS

Prior art (figs 1-4):

Prior art automated storage and retrieval system 0 Framework structure 2 Upright members of framework structure 4 Storage grid 5 Storage column 6 Storage container 6’ Particular position of storage container 7 Stack 8 Rail system o Parallel rails in first direction ( ) 2 Access opening 9 First port column 0 Second port column 1 Prior art container handling vehicle 1a Vehicle body of the container handling vehicle 201 1b Drive means / wheel arrangement / first set of wheels in first direction (X) 1c Drive means / wheel arrangement / second set of wheels in second direction (F) 1 Prior art cantilever container handling vehicle 1a Vehicle body of the container handling vehicle 301 1b Drive means / first set of wheels in first direction (X) 1c Drive means / second set of wheels in second direction (F) 4 Gripping device 1 Prior art container handling vehicle 1a Vehicle body of the container handling vehicle 401 1b Drive means / first set of wheels in first direction (X) 1c Drive means / second set of wheels in second direction (F) 4 Gripping device 4a Lifting band 4b Gripper 4c Guide pin 4b Lifting frame 0 Control system 0 Vehicle 1 Vehicle body 2 Center of gravity of empty vehicle 3 Combined center of gravity of vehicle carrying a container 4 Vehicle control unit 605 Cantilever structure

606 Lifting weight

607 Wheel

608 Wheel

609 Contact point

610 Contact point

611 Wheel

612 Wheel

613 Contact point

614 Weight sensor

615 Motor

616 Energy storage

617 Operating

618 Limiting

619 Measuring

620 Determining center of gravity

621 Receiving weight information

700 Automated storage and retrieval system

First direction

Y Second direction

Z Third direction

CLAUSES

Aspects and features of the present invention are defined in the following clauses.

1. A remotely operated vehicle (600) for handling a storage container (106), said remotely operated vehicle (600) arranged to work on a rail system of an automated storage and retrieval system, said rail system comprising a first set of parallel rails and a second set of parallel rails arranged perpendicular to the first set of parallel rails, said remotely operated vehicle (600) comprising a first set of wheels being arranged to engage with two adjacent rails of the first set of rails, and a second set of wheels being arranged to engage with two adjacent rails of the second set of rails, said vehicle (600) further comprising at least one motor (615) and a vehicle control unit (604), the vehicle control unit (604) configured to operate the at least one motor (615), the at least one motor (615) being operatively coupled with the wheels to move the vehicle (600) on the rail system, and the vehicle control unit (604) being configured to limit at least one of a maximum travel speed and a maximum acceleration of the vehicle (600) in at least one direction depending on the weight of a storage container (106) carried by the vehicle (600), such that a tilting of the vehicle (600) and/or wheel skidding is prevented.

2. The vehicle (600) of clause 1, wherein the vehicle (600) is a cantilever type vehicle for lifting and carrying a storage container (106) on a side of the vehicle (600) below a cantilever structure (605) of the vehicle (600).

3. The vehicle (600) of clause 1 or 2, comprising at least one weight sensor (614) configured to measure a weight of a storage container (106) carried by the vehicle (600), wherein the at least one weight sensor (614) is coupled with the vehicle control unit (604).

4. The vehicle (600) of any of the preceding clauses, wherein the vehicle control unit (604) is configured to limit the maximum travel speed and/or acceleration of the vehicle (600) depending on the position of the combined center of gravity (603) of the vehicle (600) carrying a storage container (106), which position depends on the weight of the storage container (106).

5. The vehicle (600) of clause 3 and 4, wherein the vehicle control unit (604) is configured to determine the position of the combined center of gravity (603) based on the measured weight of the storage container (106) carried by the vehicle (600).

6. The vehicle (600) of clause 4, wherein the vehicle control unit (604) is configured to receive weight information for the storage container (106) carried by the vehicle (600) from externally, and to determine the position of the combined center of gravity (603) based on the received weight information.

7. The vehicle (600) of any of the preceding clauses, wherein the vehicle control unit (604) is configured to limit the maximum travel speed in a first direction of travel, wherein the first direction of travel is defined by the orientation of the container (106) carried by the vehicle (600) relative to a body (601) of the vehicle (600).

8. The vehicle (600) of clause 7, wherein the vehicle control unit (604) is configured to limit a maximum acceleration in a second direction of travel, wherein the second direction of travel is opposite to the first direction.

9. Method for operating a vehicle (600) for handling a storage container (106), said vehicle (600) working on a rail system of an automated storage and retrieval system, said rail system comprising a first set of parallel rails and a second set of parallel rails arranged perpendicular to the first set of parallel rails, said vehicle (600) comprising a first set of wheels being arranged to engage with two adjacent rails of the first set of rails, and a second set of wheels being arranged to engage with two adjacent rails of the second set of rails, said vehicle (600) further comprising at least one motor (615), and a vehicle control unit (604), the method comprising: operating the at least one motor (615) operatively coupled with the wheels to move the vehicle (600) on the rail system, and limiting (610) a maximum travel speed of the vehicle (600) depending on the weight of a storage container (106) carried by the vehicle (600), through the vehicle control unit (604).

10. Method of clause 9, comprising measuring a weight of a storage container (106) carried by the vehicle (600) through at least one weight sensor connected to the vehicle control unit (604).

11. Method of clause 9 or 10, wherein limiting (610) the maximum travel speed of the vehicle (600) is conducted depending on the position of the combined center of gravity of the vehicle (600) carrying a storage container (106), which position depends on the weight of the storage container (106).

12. Method of clauses 10 and 11, comprising determining the position of the combined center of gravity based on the measured weight of the storage container (106) carried by the vehicle (600) through the vehicle control unit (604).

13. Method of clause 11, comprising receiving weight information of the storage container (106) carried by the vehicle (600) from externally, and determining the position of the combined center of gravity based on the received weight information through the vehicle control unit (604). 14- Method of any of the clauses 9 to 13, wherein limiting (610) the maximum travel speed comprises limiting (610) the maximum travel speed in a first direction of travel, wherein the first direction of travel is defined by the orientation of the container (106) carried by the vehicle (600) relative to a body (601) of the vehicle (600).

15. Method of clause 14, comprising limiting (611) a maximum acceleration in a second direction of travel through the vehicle control unit (604), wherein the second direction of travel is opposite to the first direction.

16. An automated storage and retrieval system, comprising: a rail system (108) comprising a first set of parallel rails (110) arranged in a horizontal plane and extending in a first direction (X), and a second set of parallel rails (111) arranged in the horizontal plane and extending in a second direction (Y) which is orthogonal to the first direction (X), which first and second sets of rails (110, 111) form a grid pattern in the horizontal plane comprising a plurality of adjacent grid cells, each comprising a grid opening defined by a pair of neighboring rails (110) of the first set of rails (110) and a pair of neighboring rails (111) of the second set of rails (111); a plurality of stacks (107) of storage containers (106) arranged in storage columns (105) located beneath the rail system (108), wherein each storage column (105) is located vertically below a grid opening; at least one remotely operated vehicle (600) for handling a storage container (106) according to any of the clauses 1 to 8 being configured to move on the rail system (108) above the storage columns (105).

Claims

1. A remotely operated vehicle (600) for handling a storage container (106), said remotely operated vehicle (600) comprising wheels, at least one motor (615) and a vehicle control unit (604), the vehicle control unit (604) configured to operate the at least one motor (615), the at least one motor (615) being operatively coupled with the wheels to move the vehicle (600), and the vehicle control unit (604) being configured to limit at least one of a maximum travel speed and a maximum acceleration of the vehicle (600) in at least one direction depending on the weight of a storage container (106) carried by the vehicle (600), such that a tilting of the vehicle (600) and/or wheel skidding is prevented.

2. The vehicle (600) of claim 1, wherein the vehicle is arranged to work on a rail system of an automated storage and retrieval system, said rail system comprising a first set of parallel rails and a second set of parallel rails arranged perpendicular to the first set of parallel rails, said wheels of said remotely operated vehicle (600) comprising a first set of wheels being arranged to engage with two adjacent rails of the first set of rails, and a second set of wheels being arranged to engage with two adjacent rails of the second set of rails,

3. The vehicle (600) of claim 1 or claim 2, wherein the vehicle (600) is a cantilever type vehicle for lifting and carrying a storage container (106) on a side of the vehicle (600) below a cantilever structure (605) of the vehicle (600).

4. The vehicle (600) of any preceding claim, comprising at least one weight sensor (614) configured to measure a weight of a storage container (106) carried by the vehicle (600), wherein the at least one weight sensor (614) is coupled with the vehicle control unit (604).

5. The vehicle (600) of any preceding claim, wherein the vehicle control unit (604) is configured to limit the maximum travel speed and/or acceleration of the vehicle (600) depending on the position of the combined center of gravity (603) of the vehicle (600) carrying a storage container (106), which position depends on the weight of the storage container (106).

6. The vehicle (600) of claim 4 or 5, wherein the vehicle control unit (604) is configured to determine the position of the combined center of gravity (603) based on the measured weight of the storage container (106) carried by the vehicle (600).

7. The vehicle (600) of claim 5, wherein the vehicle control unit (604) is configured to receive weight information for the storage container (106) carried by the vehicle (600) from externally, and to determine the position of the combined center of gravity (603) based on the received weight information.

8. The vehicle (600) of any preceding claim, wherein the vehicle control unit (604) is configured to limit the maximum travel speed in a first direction of travel, wherein the first direction of travel is defined by the orientation of the container (106) carried by the vehicle (600) relative to a body (601) of the vehicle (600).

9. The vehicle (600) of claim 8, wherein the vehicle control unit (604) is configured to limit a maximum acceleration in a second direction of travel, wherein the second direction of travel is opposite to the first direction.

10. Method for operating a vehicle (600) for handling a storage container (106), said vehicle (600) said comprising wheels, at least one motor (615), and a vehicle control unit (604), the method comprising: operating the at least one motor (615) operatively coupled with the wheels to move the vehicle (600), and limiting (610) a maximum travel speed of the vehicle (600) depending on the weight of a storage container (106) carried by the vehicle (600), through the vehicle control unit (604).

11. Method of claim 10, wherein said vehicle is working on a rail system of an automated storage and retrieval system, said rail system comprising a first set of parallel rails and a second set of parallel rails arranged perpendicular to the first set of parallel rails, said wheels of said vehicle (600) comprising a first set of wheels being arranged to engage with two adjacent rails of the first set of rails, and a second set of wheels being arranged to engage with two adjacent rails of the second set of rails,

12. Method of claim 10, comprising measuring a weight of a storage container (106) carried by the vehicle (600) through at least one weight sensor connected to the vehicle control unit (604).

13. Method of any of claims 10 to 12, wherein limiting (610) the maximum travel speed of the vehicle (600) is conducted depending on the position of the combined center of gravity of the vehicle (600) carrying a storage container (106), which position depends on the weight of the storage container (106).

14. Method of claims 12 or 13, comprising determining the position of the combined center of gravity based on the measured weight of the storage container (106) carried by the vehicle (600) through the vehicle control unit (604).

15. Method of claim 13, comprising receiving weight information of the storage container (106) carried by the vehicle (600) from externally, and determining the position of the combined center of gravity based on the received weight information through the vehicle control unit (604).

16. Method of any of the claims 10 to 15, wherein limiting (610) the maximum travel speed comprises limiting (610) the maximum travel speed in a first direction of travel, wherein the first direction of travel is defined by the orientation of the container (106) carried by the vehicle (600) relative to a body (601) of the vehicle (600).

17. Method of claim 16, comprising limiting (611) a maximum acceleration in a second direction of travel through the vehicle control unit (604), wherein the second direction of travel is opposite to the first direction.

18. An automated storage and retrieval system, comprising: at least one remotely operated vehicle (600) for handling a storage container (106) according to any of the claims 1 to 9.

19. The automated storage and retrieval system of claim 18, further comprising: a rail system (108) comprising a first set of parallel rails (110) arranged in a horizontal plane and extending in a first direction (X), and a second set of parallel rails (111) arranged in the horizontal plane and extending in a second direction (Y) which is orthogonal to the first direction (X), which first and second sets of rails (110, 111) form a grid pattern in the horizontal plane comprising a plurality of adjacent grid cells, each comprising a grid opening defined by a pair of neighboring rails (110) of the first set of rails (110) and a pair of neighboring rails (111) of the second set of rails (111); a plurality of stacks (107) of storage containers (106) arranged in storage columns (105) located beneath the rail system (108), wherein each storage column (105) is located vertically below a grid opening; wherein said at least one remotely operated vehicle (600) is configured to move on the rail system (108) above the storage columns (105).

20. A computer program comprising executable instructions which, when executed by at least one processor, implement the method of any of claims 10 to 17.