Patent Publication Number: US-2023160916-A1

Title: Distribution system

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to European Patent Application No. 21210129.9, filed 24 Nov. 2021, the disclosure of which is hereby incorporated by reference in its entirety. 
     TECHNICAL FIELD 
     The present disclosure relates to a distribution system. The distribution system of the present disclosure, as an example, may be used for controlling movements of tube holders transporting sample containers, in particular sample tubes, filled with biological fluids to be analyzed or reagents, and/or cassettes with reagents, specimen slides, tissue material, waste, disposables like pipette tips or tube caps, and/or empty tubes for aliquoting, specifically in the field of diagnostic laboratories. However, other fields of application for the system requiring controlling movement of carriers transporting payload are also feasible. 
     BACKGROUND 
     In the field of diagnostic laboratories, generally, a plurality of samples, for example liquid samples, have to be handled automatically. The automatic handling of samples may comprise automatically transporting sample containers, specifically sample containers comprising the samples to be handled, via tube holders in the diagnostic laboratory by means of one or more distribution systems. 
     For example, WO 2011/138448 A1 discloses a system for transporting containers between different stations, wherein the containers are accommodated in container carriers. The system comprises a control unit, which controls the transportation of the container carriers, a transporting surface, which is subdivided into sub-surfaces and on which the container carriers can be arranged in a movable manner, and drive means, wherein the drive means are activated by the control unit. One drive means in each case is assigned to one sub-surface in each case. A drive means in each case is designed in order to provide an associated container carrier with driving power. 
     WO 2014/016199 A1 describes an automation module for the manual introduction and pick up of biological specimens to be directly interfaced with a testing module for laboratory diagnostics. The automation module comprises a pair of main lanes and one of secondary lanes on which carrying devices travel for carrying tubes containing said biological specimens. The automation module is provided with separate points for the introduction and the pickup of said tubes into/from said carrying devices, said points being along the secondary lane opposite being interfaced with said testing module. 
     U.S. Pat. No. 10,006,927 B2 discloses a method of operating a laboratory automation system. The laboratory automation system comprises a plurality of laboratory stations and a plurality of sample container carriers. The sample container carriers carry one or more sample containers. The sample containers comprise samples to be analyzed by the laboratory stations. The system also comprises a transport plane. The transport plane supports the sample container carriers. The system also comprises a drive. The drive moves the sample container carriers on the transport plane. The method comprises, during an initialization of the laboratory automation system, logically reserving at least one buffer area on the transport plane and, after the initialization of the laboratory automation system, buffering in the at least one buffer area sample container carriers carrying sample containers comprising samples waiting for a result of an analysis. Depending on the result of the analysis, the samples are further processed. 
     U.S. Pat. No. 9,902,572 B2 describes a method of configuring a laboratory automation system. The position of a laboratory station is detected automatically. A laboratory sample distribution system and a laboratory automation system adapted to perform such a method are also described. 
     EP 3 410 123 A1 discloses a method of operating a laboratory sample distribution system. The laboratory sample distribution system comprises: a number of sample container carriers, wherein each of the sample container carriers comprises at least one magnetically active device and wherein each of the sample container carriers is adapted to carry at least one sample container; a number of interconnected transport plane modules, wherein each of the transport plane modules is adapted to support a number of said sample container carriers; and a number of electro-magnetic actuators, wherein below each transport plane module a number of said electro-magnetic actuators is stationary arranged in rows and columns, wherein the electro-magnetic actuators are adapted to move a sample container carrier of said sample container carriers on top of said transport plane modules along a row of said rows or along a column of said columns by applying a magnetic move force to said sample container carrier. The method comprises the steps: a) assigning at least one transport plane module of said transport plane modules to a route category, wherein at least two traffic lanes are formed on the route categorized transport plane module, wherein said sample container carriers are moved within each traffic lane in a given transport direction, wherein the transport directions of the at least two traffic lanes are opposite to each other and wherein a change from one transport direction to the opposite transport direction is not possible for said sample container carriers moved on the route categorized transport plane module; b) assigning at least one another transport plane module of said transport plane modules to a waypoint category, wherein a change from one transport direction to the opposite transport direction is enabled for said sample container carriers moved on the waypoint categorized transport plane module. 
     WO 2016/188865 A1 describes method of operating a laboratory sample distribution system, wherein the laboratory sample distribution system comprises: a number of sample container carriers, wherein the sample container carriers are adapted to carry one or more sample containers, wherein the sample containers comprise samples to be analyzed by means of a number of laboratory stations, and a transport plan, wherein the transport plane is adapted to support the sample container carriers. The method comprises the steps: allocating an area of the transport plane as a buffer area, wherein the buffer area is adapted to store a variable number of sample container carriers, and controlling the buffer area using a puzzle-based control scheme or using an aisle-based control scheme as a function of a storage density of the buffer area. 
     Despite the advantages achieved by known methods and devices, several technical challenges remain. Specifically, known routing algorithms may generally not contain any queuing logic. However, suitable queuing strategies in distribution systems may be needed to absorb and reduce system variability. These queuing strategies should have minimum impact on routing the tube holders. Further, known routing algorithms generally do not comprise a queuing logic but would route tube holders from one queue field to another queue field. However, queuing strategies must ensure that queue fields are empty on arrival of the tube holder. 
     SUMMARY 
     Although the embodiments of the present disclosure are not limited to specific advantages or functionality, it is noted that in accordance with the present disclosure a distribution system is provided that reduces system variability and increases robustness of continuous operation, in particular in changing conditions. 
     In accordance with one embodiment of the present disclosure, a distribution system is provided comprising: a transport plane configured for distributing a plurality of tube holders, wherein the transport plane comprises at least one transportation area and at least one queue area, wherein the queue area comprises queues of a plurality of different queue types differentiating between tube holder with a sample container, empty tube holder, input queue and output queue; a drive system configured for moving the tube holders on the transport plane; and a control system configured to control movement of the tube holders on the transport plane, wherein the control system comprises a routing system configured for calculating routes for the tube holders on the transportation area of the transport plane, wherein the control system comprises a queue manager configured for calculating routes for the tube holders in the queue area considering the different queue types. 
     These and other features and advantages of the embodiments of the present disclosure will be more fully understood from the following detailed description taken together with the accompanying claims. It is noted that the scope of the claims is defined by the recitations therein and not by the specific discussions of features and advantages set forth in the present description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following detailed description of the embodiments of the present description can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which: 
         FIG.  1    shows an embodiment of a distribution system in a schematic view; 
         FIG.  2    shows exemplary static queues on a transport plane; and 
         FIG.  3    shows exemplary dynamic shared queues on a transport plane. 
     
    
    
     Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not been drawn to scale. For example, dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of the embodiment(s) of the present disclosure. 
     DETAILED DESCRIPTION 
     As used in the following, the terms “have”, “comprise” or “include” or any arbitrary grammatical variations thereof are used in a non-exclusive way. Thus, these terms may both refer to a situation in which, besides the feature introduced by these terms, no further features are present in the entity described in this context and to a situation in which one or more further features are present. As an example, the expressions “A has B”, “A comprises B” and “A includes B” may both refer to a situation in which, besides B, no other element is present in A (i.e., a situation in which A solely and exclusively consists of B) and to a situation in which, besides B, one or more further elements are present in entity A, such as element C, elements C and D or even further elements. 
     Further, it shall be noted that the terms “at least one”, “one or more” or similar expressions indicating that a feature or element may be present once or more than once typically will be used only once when introducing the respective feature or element. In the following, in most cases, when referring to the respective feature or element, the expressions “at least one” or “one or more” will not be repeated, non-withstanding the fact that the respective feature or element may be present once or more than once. 
     Further, as used in the following, the terms “typically”, “more typically”, “particularly”, “more particularly”, “specifically”, “more specifically” or similar terms are used in conjunction with optional features, without restricting alternative possibilities. Thus, features introduced by these terms are optional features and are not intended to restrict the scope of the claims in any way. The present disclosure may, as the skilled person will recognize, be performed by using alternative features. Similarly, features introduced by “in an embodiment of the present disclosure” or similar expressions are intended to be optional features, without any restriction regarding alternative embodiments of the present disclosure, without any restrictions regarding the scope of the present disclosure and without any restriction regarding the possibility of combining the features introduced in such way with other optional or non-optional features of the present disclosure. 
     In a first aspect of the present disclosure, a distribution system is disclosed. The distribution system comprises:
         a transport plane configured for distributing a plurality of tube holders, specifically a plurality of single tube holders, wherein the transport plane comprises at least one transportation area and at least one queue area, wherein the queue area comprises queues of a plurality of different queue types differentiating between tube holder with a sample container, empty tube holder, input queue and output queue;   a drive system configured for moving the tube holders on the transport plane;   a control system configured to control movement of the tube holders on the transport plane, wherein the control system comprises a routing system configured for calculating routes for the tube holders on the transportation area of the transport plane, wherein the control system comprises a queue manager configured for calculating routes for the tube holders in the queue area considering the different queue types.       

     The term “system” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary set of interacting or interdependent components forming a whole. Specifically, the components may interact with each other in order to fulfill at least one common function. The system may comprise at least two components, wherein the at least two components may be handled independently or may be coupled or connectable. 
     The term “distribution system” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a system configured for distributing tube holders from an initial position to a target destination. The distribution system may be an element of a laboratory automation system allowing to distribute tube holders to a target destination within the laboratory automation system. Distribution systems may be used in laboratory automation systems comprising a number of laboratory stations, for example pre-analytical, analytical and/or post-analytical stations. Distribution system are generally known by the skilled person e.g., from EP 3 095 739 A1 or WO 2012/158541. 
     The term “tube holder”, also denoted as carrier, as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a support structure configured for supporting and transporting a payload. The tube holder may be provided with appropriate holding means to support, and if required, to secure payload in a needed manner and orientation. The tube holder may be configured for receiving and/or holding at least one sample container, specifically at least one sample tube. The sample container may be or may comprise a laboratory diagnostic container or vessel, in particular a sample tube, filled with biological fluid to be analyzed, and/or cassettes filled with reagents, specimen slides, tissue material, waste, disposables like pipette tips or tube caps, and/or empty tubes for aliquoting, and the like. For example, the tube holder may be a single tube holder configured for receiving and/or holding one sample container. The tube holder can be self-propelling or can be propelled by and moved on a transport plane. 
     The term “tube holder with a sample container” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a tube holder comprising at least one sample container, specifically at least one sample tube. 
     The term “empty tube holder” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an unloaded tube holder. The empty tube holder may be a tube holder without a sample container. The empty tube holder may be configured for receiving at least one sample container, specifically at least one sample tube. 
     The term “transport plane” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to any kind of two dimensional plane, bed, layer, platform or base configured for transporting tube holders. The transport plane may be configured such that tube holders are positionable onto the transport plane, in particular on a surface of the transport plane, such that the tube holders are movable in at least two dimensions along the transport plane. For instance, the transport plane may be a sliding surface mounted in a diagnostics laboratory or the floor of a manufacturing site or inside a manufacturing hall. The transport plane may be installed vertically or horizontally including slopes. Also, curved transport planes may be possible. 
     The transport plane may be configured for providing movement of the tube holder by contact. The transport plane may be configured such that a tube holder can contact the surface of the transport plane, also denoted as transport surface, such that friction can be used to drive, stop and control movements of the tube holder. The tube holder may be in contact with the transport surface for a part of a node-to-node transportation duration, for example when the tube holders stop to wait for a next move. For a third dimension, either the transport plane may be formed correspondingly with corresponding limitations in upward and downward slope, or some kind of levitation mechanism may be installed such as magnetic levitation or air cushion technique with the corresponding limitations in reachable height without losing control. For vertical transportation in the third dimension, elevators or paternoster mechanisms can also be installed. 
     Tube holders on the transport plane may be identified by an identification or registration system. The identification and registration system can comprise at least one camera system and/or at least one optical sensor and/or at least one scanner identifying one or more of any optical signature on the tube holder or sample container, such as one or more of its size, its type, a bar code, a QR code, its payload. The barcode and/or QR code may be used to identify the tube holder. Alternatively or in addition, at least one RFID-reader system reading a unique RFID of the tube holder or sample container on the tube holder or sensors inside the transport plane can be used to identify positions and to localize the tube holders. A further option can be high precision GPS, in particular enhanced with Wi-Fi, Bluetooth and/or GSM signals. Any other suitable alternative can be in principle also used. 
     The transport plane may be divided into at least one transportation area and at least one queue area. 
     The term “transportation area” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a partial plane of the transport plane configured for transporting of tube holders from their respective initial position to a final position, e.g., from one laboratory station to another laboratory station. The transporting of the tube holders on the transportation area may be defined by using at least one routing algorithm. An order and/or sequence of the tube holders may change during transportation on the transporting area. Specifically, main traffic of tube holders may take place on the transportation area of the transport plane. Transportation of tube holders on the transportation area, in particular the main traffic of tube holders, may be controlled by at least one routing algorithm. 
     The transportation area may comprise a plurality of transportation fields. Transportation fields may be defined on the transport plane by hardware requirements and/or by software. The transportation fields may be imaginary positions in the routing algorithm and/or positions on the real transport plane. For example, a transportation field may be defined on the transport plane as a position at which the tube holder can stop, start and/or change direction. In systems such as described in EP 2 566 787 or WO 2013/098202, the drive system, as will be described in further detail below, may define these transportation fields by its hardware limitations. Transportation fields may be defined above an electro-magnetic coil. At these positions, it may be possible to stop the tube holder and to change its direction with the next move. The transportation fields may be defined as wanted or required to form a useful set of crossing points, junctions, start and stop positions. The transportation field may be a discrete position where the tube holder can stop. In particular, the transportation field may be defined by at least one physical entity of the drive system, such as an electromagnetic coil or a crossing of possible ways such as rails. Each of the transportation fields may be configured for being occupied by only one tube holder. Thus, two tube holders cannot share one transportation field. The transportation fields of the transportation area may be arranged adjacent to each other to form part of the two dimensional transport plane. For example, the transportation fields may comprise a rectangular shape, such as a quadratic shape, and may be arranged in a checkerboard pattern. However, other forms of the transportation fields may be also possible, in principle, such as a polygonal shape, for example hexagonal transportation fields arranged in a honeycomb pattern. 
     Transportation of the tube holders in the transportation area may comprise transporting the tube holders via the transportation fields, such as from their respective initial transportation field to a final transportation field. Specifically, the transportation of the tube holders on the transportation area may comprise moving the tube holders according to their calculated routes from their initial position to the final position. The term “route” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a set of partial routes from a start position to a final destination position. The route may be divided into one or more partial routes to intermediate destinations. The start position may be a transportation field where the tube holder stands on the transportation area when the routing algorithm starts calculating the route. The final destination position may be a transportation field on the transportation area where the tube holder needs to go to. Final destination positions may also be fields on the transport plane of a second, separately routed area, specifically queuing fields of the queue area, as will be outlined in further detail below. A start position for one tube holder can also be in particular a final destination position for another tube holder or more particular for the same tube holder. 
     The routes of the tube holders on the transportation area may be executed by an execution unit, specifically considering the calculated route, and may comprise one or more moves of the tube holder. The term “move” may refer to an “action” and may not include the waiting time before the next move will take place. A move may be defined as one movement of a tube holder in a straight line, starting from one transportation field and stopping at a second, different transportation field. A move can comprise a displacement of a tube holder of one or multiple transportation fields. Specifically, a move on the transportation area may comprise a displacement of tube holders of multiple transportation fields. The move length may be a number of transportation fields for each move. Specifically, a move may be a straight-line displacement without stopping the tube holder in between. Moving from a first final destination to a second final destination may be carried out in one or more moves with intermediate destinations. Each move has a start and a stop on a transportation field on the transport plane. The intermediate destination may also be a transportation field on the transport plane. The stop of a last move of a route is either an intermediate destination or a final destination. 
     The term “queue area” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a partial plane of the transport plane configured for storing a plurality of transport tubes to be processed and/or to be held for being processed by the transport area. For example, the queue area may have a function of a buffer. The term “queue” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a collection of tube holders to be stored and/or buffered, to be processed and/or to be held for being processed by the transport area. The queue may be designed such that the tube holders are maintained in a sequence, wherein tube holders can be added, also denoted as enqueuing, to the queue at one end of the sequence and can be removed from the queue from the other end of the sequence. The end of the sequence at which tube holders can be added may be called the back, tail, or rear of the queue. The other end, at which the tube holders can be removed, also denoted as dequeuing, may be called the head or front of the queue. For example, tube holders may be queued for being one or more of: removed from the transport plane, specifically being removed from the queue area of the transport plane, for example in order to supply connected devices, such as laboratory stations, with tube holders and/or sample tubes; inserted to the transport plane, specifically being inserted to the transportation area of the transport plane. The queue area may be operated as a first-in-first-out (FIFO) queue such that the first tube holder added to the queue area will be the first one to be removed. However, other queues, such as random access queues or queues comprising tube holders with enhanced priority, are also feasible. 
     The queue area may comprise a plurality of queue fields. The queue fields of the queue area may be embodied similar to the transportation fields of the transportation area. However, queue fields may comprise positions on the transport plane which have a special functionality, e.g., where a tube holder, a part of the sample, or a consumable is handed over from or to the transport plane to or from e.g., an analyzer or pre- or post-analytical system or storage system. Analogous to the transportation fields of the transport area, the queue fields may be arranged adjacent to each other to form part of the two dimensional transport plane. For example, the queue fields may comprise a rectangular shape, such as a quadratic shape, and may be arranged in a checkerboard pattern. However, other forms of the queue fields may be also possible, in principle, such as a polygonal shape, for example hexagonal queue fields arranged in a honeycomb pattern. 
     Tube holders may be movable in the queue area. Specifically, tube holders may be movable in the queue area according to the routes calculated by the queue manager. The routes of tube holders in the queue area may be or may comprise a set of partial routes from a start position to a final destination position, wherein the start position and/or the final destination position of the route may be queue fields. Specifically, the route may comprise one or more moves of the tube holder via the queue fields. A move may be defined as one movement of a tube holder in a straight line, starting from one queue field and stopping at a second, different queue field. A move can comprise a displacement of a tube holder of one or multiple queue fields. For example, a move on the queue area may comprise a move adding a tube holder to a respective queue. Thus, in this case, the move may comprise a displacement of the tube holder to be added to a certain queue to the back of the queue. Alternatively or additionally, a move on the queue may comprise a move of a queueing tube holder, i.e., of a tube holder comprised by a certain queue. In this case, the move may comprise a displacement of the queueing tube holder as far ahead as possible in order to advance further in the queue. A move of the tube holder inside the respective queue in one direction may be as far ahead as possible without causing any collisions or claiming fields of the transport plane of other tube holders. The moves of the tube holders in the queue area may be performed, similar to the moves of the tube holders in the transportation area, by the drive system, as will be described in further detail below. However, moves on the queue area may maintain an order or sequence of the tube holders within the respective queue. 
     In the queue area, tube holders may form queues according to different queue types differentiating between tube holder with a sample container, empty tube holder, input queue and output queue. The term “queue type” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to different usages of parts of the queue area. The queue type may be at least one criterion distinguishing parts of the queue area depending on the type of tube holders queued in the respective part. The type of tube holder may refer to one or more of tube holders with a sample container, empty tube holders, tube holders designated for being inserted to the transportation area, and tube holders designated for being removed from the transportation area. 
     The queue area comprises queues of a plurality of different queue types differentiating between tube holder with a sample container, empty tube holder, input queue and output queue. 
     The term “input queue” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a queue configured and/or assigned and/or reserved for comprising tube holders designated for being inserted to the transportation area of the transport plane. 
     The term “output queue” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a queue configured and/or assigned and/or reserved for comprising tube holders designated for being removed from the transport plane, specifically from the queue area of the transport plane. 
     For example, the queue area may comprise a sample container output queue, a sample container input queue, an empty tube holder output queue, and an empty tube holder input queue. The term “sample container output queue” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a queue configured and/or assigned and/or reserved for supplying connected devices with sample containers. In the sample container output queue, tube holders with a sample container may be queueing. The sample container output queue may be used to modulate fluctuations in number of sample container arrivals. The sample container output queue may be split into emergency (STAT) samples and routine samples. Emergency (STAT) samples may be samples with enhanced priority. The STAT samples may be samples which require a short turnaround time, e.g., an hour or less from specimen receipt until result reporting. The queue manager may be configured for calculating the route of a tube holder loaded with a STAT sample so that it can skip part of the sample container output queue. The sample container output queue may be used for continuous supply of sample containers to connected devices, such as to laboratory stations of laboratory automation systems. “STAT” may be a type of priority. Orders, samples or any other element with this priority may be handled by the system with the highest priority. A STAT sample may be a sample that is or is required to be processed with the highest priority. “Routine” may be a type of priority. Elements, e.g., samples, with this priority may be handled by the system in a regular way. A routine sample may be a sample that is processed in a regular way, thus not with high priority. 
     The term “sample container input queue” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a queue configured and/or assigned and/or reserved for queuing tube holders entering the transport plane. The sample container input queue may be configured for storing tube holders with a sample container entering the transportation area. For tube holders in the sample container input queue, the control system, specifically the routing system, may decide their next target considering delays between query and response. The tube holders may be stored in the sample container input queue until their next target is known. The sample container input queue may be a random access queue or a First-IN-First-out queue. Random access queue may be beneficial when long delays for the query occur. 
     The term “empty tube holder output queue” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a queue configured and/or assigned and/or reserved for storing empty tube holders for being provided to connected devices. The empty tube holder output queue may be configured for providing a constant supply of empty tube holders at a loading position of the transport plane to connected devices. The empty tube holder output queue may guarantee constant supply such that connected devices reach their stated throughput. The empty tube holder output queue may have a high capacity in order to modulate fluctuations of tube holder demands by connected devices. 
     The term “empty tube holder input queue” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a queue configured and/or assigned and/or reserved for storing empty tube holders for being provided to the transport plane, specifically to the transportation area of the transport plane. The empty tube holder input queue may be configured for storing empty tube holder from a transport interface of the distribution system to provide access to the transportation area to travel to its next target. The empty tube holder input queue may have storage capacity in order to account for delays of empty tube holders moving from the empty tube holder input queue to the transportation area when traffic on the transportation area is dense. The empty tube holder input queue may free connected devices from empty tube holders in order to not block the connected devices. 
     The queues may be static queues which are placed such their purpose is fulfilled while minimizing their obstruction with a main traffic of tube holders on the transportation area. Each of the queues may comprise a plurality of queue fields. The queue fields may be fields on the transport plane. 
     The transport plane may comprise at least one dynamic shared queue having at least one dynamic shared queue field. The term “dynamic shared queue field” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a transportation field which is temporarily assignable as queue field. The routing system may be configured for dynamically assigning the at least one dynamic shared queue field of the dynamic shared queue to every tube holder on the transport plane. The dynamic shared queue may be a random access queue. Tube holders within the dynamic shared queue may be not movable. The dynamic shared queue field may specifically be a queue with capacity of one tube holder, where tube holders can drive on from the transportation area and later drive off again. Tube holders may only drive on the dynamic shared queue field if it is the final target field. The routing system may be configured for assigning all dynamic shared queue fields to a list of forbidden fields such that tube holders can only drive on a dynamic shared queue field if it is its final target field. 
     A location of the at least one dynamic shared queue field on the transport plane may be selected according to the following rules:
         a field of the transport plane, if it does not contain static queues or if it is directly connected to a field with static queues; and   if there are exactly three neighboring fields physically available.       

     For example, the dynamic shared queue may be arranged on an outer lane of the transportation area. The location of the dynamic shared queue fields may be selected such that its interference with the main traffic on the transportation area is minimal and a high number of dynamic shared queue fields are available in a layout. The location of the dynamic shared queue fields may be selected such that fields on the transportation area having only two neighboring fields may be excluded, e.g., transportation fields around corners may be excluded from dynamic shared queues as they may be not reachable. The term “high” number of dynamic shared queue fields may be referred to in relation to the number of tube holders on the system. A high ratio may be 1:1 and/or situations where more shared queue fields than tube holders are available. The term “high” number of dynamic shared queue fields may also be referred to in relation to density. The density may relate to the ability to get sample carriers from the dynamic queue to the static queue in time to avoid starvation. This may be dependent on one or more of drive velocity, drive time predictability and the density, e.g., how much queue capacity is available in the neighborhood. One can trade off the local dynamic shared queue capacity and static queue capacity with the risk of starvation. One would need to pick a meaningful tradeoff for the application. A very large static queue would be a good guard against starvation, but obviously comes at a cost. The categorization as “high” number of dynamic shared queue fields may depend on the system size. 
     A combination of static queues, which may be used by tube holders being assigned to a specific connected device, and dynamic shared queues, which may be used by all tube holders on the transport plane, may allow a proper queueing behavior while minimizing the overall queue capacity and a bad impact on the main traffic on the transport plane. 
     As outlined above, the distribution system comprises the drive system configured for moving the tube holders on the transport plane and the control system configured to control movement of the tube holders on the transport plane. The term “drive system” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a system configured for moving tube holders on the transport plane. The drive system can be implemented in the tube holders itself e.g., wheels connected to an electric motor with or without connected battery and electronics. Another possibility are linear motors. Also possible are passive tube holders. For instance, the tube holder may comprise and/or may be at least one magnetic element. For example, a magnetic device is fixed in the tube holder and/or the tube holders may be made of a magnetic, e.g., paramagnetic, material. A magnetic force may be provided by magnetically active and drivable elements such as electro-magnetic coils, enforcing the tube holders to move by generated electro-magnetic fields. The coils can be installed under, above, besides or in the transport plane. For instance, an arrangement of magnetic coils underneath the transport plane is described e.g., in EP 2 566 787 or WO 2013/098202. Additionally or alternatively, the coils may be inside the tube holder and the permanent magnets in the transport plane. 
     The term “control system” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary system configured for performing the named operations, typically by using at least one data processing device and, more typically, by using at least one processor and/or at least one application-specific integrated circuit. Thus, as an example, the at least one control system may comprise at least one data processing device having a software code stored thereon comprising a number of computer commands. The control system may provide one or more hardware elements for performing one or more of the named operations and/or may provide one or more processors with software running thereon for performing one or more of the named operations. The control system may comprise one or more programmable devices such as one or more computers, application-specific integrated circuits (ASICs), Digital Signal Processors (DSPs), or Field Programmable Gate Arrays (FPGAs) which are configured to perform a control function. The control system may comprise at least one computer. The computer can be an embedded computer e.g., micro controller or programmable logic devices such as FPGAs. Additionally or alternatively, however, the control system may also fully or partially be embodied by hardware. 
     As outlined above, the control system comprises the routing system configured for calculating routes for the tube holders on the transportation area of the transport plane and the queue manager configured for calculating routes for the tube holders in the queue area considering the different queue types. Additionally, the control system may comprise at least one execution unit for execution of movements of the tube holders according to the calculated routes. 
     The term “routing system” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to an arbitrary system configured for calculating routes for moving the tube holders on the transport plane. The routing system may comprise at least one data processing device. The routing system may be configured for using at least one algorithm, in particular denoted as routing algorithm. A routing algorithm may be an algorithm calculating a route for each tube holder on the transport plane from a start position to an intermediate destination position towards a final destination position. The routing algorithm may calculate several straight moves for each route starting with the current position of the tube holder as a starting position to an intermediate destination position. The planned route, also denoted as routing plan, may comprise all moves or only the next few moves to carry out until a second final destination is reached. The routing system may be functionally separated from the execution unit. However, the two processes of calculating routes performed by the routing system and executing the calculated routes performed by the execution unit can run on the same computer, on the same or multiple computation cores etc. or on different computers and/or microcontrollers etc. 
     The term “queue manager” as used herein is a broad term and is to be given its ordinary and customary meaning to a person of ordinary skill in the art and is not to be limited to a special or customized meaning. The term specifically may refer, without limitation, to a hardware and/or software implemented system configured for calculating routes for the tube holders in the queue area considering the different queue types. The queue manager may comprise at least one data processing device, specifically being comprised by the control system. Additionally or alternatively, the queue manager may be a software implemented system comprising instructions, e.g., at least one algorithm, which, when executed by the control system, cause the control system to perform the queueing logic as described in further detail above. The queue manager may be configured for routing tube holders, specifically for calculating and/or executing routes for the tube holders, in the queue area of the transport plane. 
     At least one queue field of the respective queue may be an interface field between the transportation area and the at least one queue area. On the interface field, one field moves may be allowed from and to the interface field on a side of the queue area. For example, a first queue field of the respective output queue and a last queue field of the respective input queue may be interface fields. The routing system and the queue manager may be configured for being aware of movement within the interface fields, specifically of movement of the queueing tube holders within the interface fields. 
     The sample container output queue may comprise an interface field to the STAT queue. The STAT queue may be the sample container output queue with the emergency (STAT) samples. The interface field may be configured for providing an interface to STAT samples to merge into the output queue of the routine samples. Starting from this interface field, the sample container output queue may comprise tube holders with both priorities, STAT sample and routine samples. In case tube holders in the sample container output queue have to be rerouted, it may be possible to route the respective tube holders through the connected devices and/or enter back to the sample container input queue and/or directly retrieve the respective tube holders through a potentially empty STAT queue and/or sample container input queue. 
     The queue manager and the routing system may be configured for interacting with each other. As outlined above, at least one queue field of the respective queue may be an interface field between the transportation area and the queue area. At the interface field, tube holders may be handed over from the routing system to the queue manager, and/or vice versa. The handing over may comprise removing the tube holders from the control of the routing system or the queue manager, and adding the tube holder to the queue manger or routing system, respectively. The interface fields may be located at the first queue field of the respective output queues and the last queue field of the respective input queues. Whenever there is a movement on one of those fields, both the routing system and the queue manager may be aware of the movement and may be ready to accept the moved tube holder. 
     In case a tube holder is routed by the routing system to the interface field, the tube holder may drive onto the interface field if the interface field is not occupied and/or reserved by other tube holders. The queue manager may be configured for adding the tube holder to the routing system by an appropriate call to the routing system before routing the tube holder to the interface field. If the tube holder is successfully added to the routing algorithm, the move onto the interface field may be executed. 
     In case a tube holder finishes a move away from the interface field, the tube holder may be removed from the routing system and/or queue manager. For the routing system, the interface fields may be added to the forbidden fields list, where moves are only allowed when it is their final target. Due to interference of unpredictable waiting times on the interface field with optimal performance of the routing system, only one field moves may be allowed from and to the interface field by the queue manager. This may reduce an occupancy on the interface field and may simplify the handover between the routing system and the queue manager. Further, the combination of the routing system and the queue manager may increase robustness of the distribution system under changing conditions, specifically for continuous operation. Specifically, the distribution system may allow reducing system variability. Generally, many stochastic influences introduce a high system variability, e.g., on the input side (arrival pattern, assigned workflows, and the like), the transport system itself (drive times, communication delays, and the like) and the operation (failures, rerouting, and the like). In order to handle the complex traffic problem, the present disclosure allows to reduce the system variability by a proper queueing management. A more deterministic problem with a lower complexity can be offered to the actual routing algorithm. 
     Further disclosed and proposed herein is a computer program including computer-executable instructions for performing the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, when the program is executed on a computer or computer network. Specifically, the computer program may be stored on a computer-readable data carrier and/or on a computer-readable storage medium. 
     As used herein, the terms “computer-readable data carrier” and “computer-readable storage medium” specifically may refer to non-transitory data storage means, such as a hardware storage medium having stored thereon computer-executable instructions. The computer-readable data carrier or storage medium specifically may be or may comprise a storage medium such as a random-access memory (RAM) and/or a read-only memory (ROM). 
     Thus, specifically, one, more than one or even all of method steps for the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, as indicated above may be performed by using a computer or a computer network, typically by using a computer program. 
     Further disclosed and proposed herein is a computer program product having program code means, in order to perform the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, the program is executed on a computer or computer network. Specifically, the program code means may be stored on a computer-readable data carrier and/or on a computer-readable storage medium. 
     Further disclosed and proposed herein is a data carrier having a data structure stored thereon, which, after loading into a computer or computer network, such as into a working memory or main memory of the computer or computer network, may execute the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types. 
     Further disclosed and proposed herein is a computer program product with program code means stored on a machine-readable carrier, in order to perform the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, when the program is executed on a computer or computer network. As used herein, a computer program product refers to the program as a tradable product. The product may generally exist in an arbitrary format, such as in a paper format, or on a computer-readable data carrier and/or on a computer-readable storage medium. Specifically, the computer program product may be distributed over a data network. 
     Finally, disclosed and proposed herein is a modulated data signal which contains instructions readable by a computer system or computer network, for performing the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types. 
     Referring to the computer-implemented aspects of the disclosure, one or more of the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, may be performed by using a computer or computer network. Thus, generally, any of the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, may be performed by using a computer or computer network. 
     Specifically, further disclosed herein are:
         a computer or computer network comprising at least one processor, wherein the processor is adapted to perform the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types,   a computer loadable data structure that is adapted to perform the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, while the data structure is being executed on a computer,   a computer program, wherein the computer program is adapted to perform the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, while the program is being executed on a computer,   a computer program comprising program means for performing the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, while the computer program is being executed on a computer or on a computer network,   a computer program comprising program means according to the preceding embodiment, wherein the program means are stored on a storage medium readable to a computer,   a storage medium, wherein a data structure is stored on the storage medium and wherein the data structure is adapted to perform the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, after having been loaded into a main and/or working storage of a computer or of a computer network, and   a computer program product having program code means, wherein the program code means can be stored or are stored on a storage medium, for performing the controlling of movements of the tube holders on the transport plane, calculating of routes for the tube holders on the transportation area of the transport plane, and/or calculating of routes for the tube holders in the queue area considering the different queue types, if the program code means are executed on a computer or on a computer network.       

     Summarizing and without excluding further possible embodiments, the following embodiments may be envisaged: 
     Embodiment 1: A distribution system comprising:
         a transport plane configured for distributing a plurality of tube holders, wherein the transport plane comprises at least one transportation area and at least one queue area, wherein the queue area comprises queues of a plurality of different queue types differentiating between tube holder with a sample container, empty tube holder, input queue and output queue;   a drive system configured for moving the tube holders on the transport plane;   a control system configured to control movement of the tube holders on the transport plane, wherein the control system comprises a routing system configured for calculating routes for the tube holders on the transportation area of the transport plane, wherein the control system comprises a queue manager configured for calculating routes for the tube holders in the queue area considering the different queue types.       

     Embodiment 2: The distribution system according to embodiment 1, wherein the queue area comprises a sample container output queue, a sample container input queue, an empty tube holder output queue, and an empty tube holder input queue. 
     Embodiment 3: The distribution system according to embodiment 2, wherein the sample container output queue is split into emergency (STAT) samples and routine samples, wherein the queue manager is configured for calculating the route of a tube holder loaded with a STAT sample so that it can skip part of the sample container output queue. 
     Embodiment 4: The distribution system according to any one of embodiments 2 or 3, wherein the sample container output queue is used for continuous supply of sample containers to connected devices. 
     Embodiment 5: The distribution system according to any one of embodiments 2 to 4, wherein the sample container input queue is configured for storing tube holders with a sample container entering the transport plane. 
     Embodiment 6: The distribution system according to embodiment 5, wherein the sample container input queue is a random access queue or a First-IN-First-out queue. 
     Embodiment 7: The distribution system according to any one of embodiments 2 to 6, wherein the empty tube holder output queue is configured for providing a constant supply of empty tube holders at a loading position of the transport plane to connected devices. 
     Embodiment 8: The distribution system according to any one of embodiments 2 to 7, wherein the empty tube holder input queue is configured for storing empty tube holder from a transport interface of the distribution system to provide access to the transportation area to travel to its next target. 
     Embodiment 9: The distribution system according to any one of embodiments 1 to 8, wherein the queues are static queues which are placed such their purpose is fulfilled while minimizing their obstruction with a main traffic of tube holders on the transportation area. 
     Embodiment 10: The distribution system according to any one of embodiments 1 to 9, wherein a move of the tube holder inside the respective queue in one direction is as far ahead as possible without causing any collisions or claiming fields of the transport plane of other tube holders. 
     Embodiment 11: The distribution system according to any one of embodiments 1 to 10, wherein each of the queues comprises a plurality of queue fields, wherein at least one queue field of the respective queue is an interface field between the transportation area and the at least one queue area. 
     Embodiment 12: The distribution system according to embodiment 11, wherein a first queue field of the respective output queue and a last queue field of the respective input queue are interface fields, wherein the routing system and the queue manager are configured for being aware of movement within the interface fields. 
     Embodiment 13: The distribution system according to any one of embodiments 11 or 12, wherein the sample container output queue comprises an interface field to the STAT queue, wherein said interface field is configured for providing an interface to STAT samples to merge into the output queue of the routine samples. 
     Embodiment 14: The distribution system according to any one of embodiments 11 to 13, wherein on the interface field one field moves are allowed from and to the interface field on a side of the queue area. 
     Embodiment 15: The distribution system according to any one of embodiments 1 to 14, wherein the transport plane comprises at least one dynamic shared queue having at least one dynamic shared queue field, wherein the routing system is configured for dynamically assigning the at least one dynamic shared queue field of the dynamic shared queue to every tube holder on the transport plane. 
     Embodiment 16: The distribution system according to embodiment 15, wherein the dynamic shared queue is a random access queue, wherein tube holders within the dynamic shared queue are not movable. 
     Embodiment 17: The distribution system according to any one of embodiments 15 or 16, wherein the routing system is configured for assigning all dynamic shared queue fields to a list of forbidden fields such that tube holders can only drive on a dynamic shared queue field if it is its final target field. 
     Embodiment 18: The distribution system according to any one of embodiments 15 to 17, wherein a location of the at least one dynamic shared queue field on the transport plane is selected according to the following rules:
         a field of the transport plane, if it does not contain static queues or if it is directly connected to a field with static queues; and   if there are exactly three neighboring fields physically available.       

     Embodiment 19: The distribution system according to any one of embodiments 15 to 18, wherein the dynamic shared queue is arranged on an outer lane of the transportation area. 
     Further optional features and embodiments will be disclosed in more detail in the subsequent description of embodiments, typically in conjunction with the dependent claims. Therein, the respective optional features may be realized in an isolated fashion as well as in any arbitrary feasible combination, as the skilled person will realize. The scope of the present disclosure is not restricted by the typical embodiments. The embodiments are schematically depicted in the Figures. Therein, identical reference numbers in these Figures refer to identical or functionally comparable elements. 
     In order that the embodiments of the present disclosure may be more readily understood, reference is made to the following examples, which are intended to illustrate the disclosure, but not limit the scope thereof. 
       FIG.  1    shows an exemplary embodiment of a distribution system  110  in a schematic view. The distribution system  110  comprises a transport plane  112  configured for distributing a plurality of tube holders  114 . Specifically, the tube holder  114  may be a single tube holder  116  configured for receiving and/or holding one sample container  118 . However, the tube holders  114  to be distributed by the transport plane  112  may also comprise tube holder racks (not shown in  FIG.  1   ) configured for receiving multiple sample containers  118 . 
     The distribution system  110  may be an element of a laboratory automation system  120  allowing to distribute tube holders  114  to a target destination within the laboratory automation system  120 . As shown in  FIG.  1   , the distribution system  110  may be used in laboratory automation systems  120  comprising a number of laboratory stations  122 , for example pre-analytical, analytical and/or post-analytical stations. Thus, in this example, the sample container  118  received by the tube holder  114  may comprise a laboratory diagnostic container or vessel, in particular a sample tube  124 , filled with biological fluid to be analyzed, and/or cassettes filled with reagents, specimen slides, tissue material, waste, disposables like pipette tips or tube caps, and/or empty tubes for aliquoting, and the like. 
     The transport plane  112  comprises at least one transportation area  126  and at least one queue area  128 . The queue area  128  comprises queues of a plurality of different queue types differentiating between tube holder  114  with a sample container  118 , empty tube holder  114 , input queue and output queue. Exemplary queues, specifically static queues and dynamic shared queues, are shown in  FIG.  2    and  FIG.  3   , respectively. Thus, for more details regarding the queues, reference is made to the description of  FIGS.  2  and  3   . 
     The distribution system  110  further comprises a drive system  130  configured for moving the tube holders  114  on the transport plane  112 . In the example of  FIG.  1   , the drive system  130  may be partially implemented in the tube holders  114  itself. The tube holders  114  may be passive tube holders. For instance, the tube holder  114  may comprise and/or may be at least one magnetic element. For example, a magnetic device is fixed in the tube holder  114  and/or the tube holders  114  may be made of a magnetic, e.g., paramagnetic, material. A magnetic force may be provided by magnetically active and drivable elements such as electro-magnetic coils (not shown in  FIG.  1   ), enforcing the tube holders  114  to move by generated electro-magnetic fields. The coils can be installed under, above, besides or in the transport plane  112 . 
     The distribution system  110  comprises a control system  132  configured to control movement of the tube holders  114  on the transport plane  112 . The control system  132  comprises a routing system  134  configured for calculating routes for the tube holders  114  on the transportation area  126  of the transport plane  112 . Further, the control system  132  comprises a queue manager  136  configured for calculating routes for the tube holders  114  in the queue area  128  considering the different queue types. 
     Tube holders  114  on the transport plane  112  may be identified by an identification or registration system  138 . As shown in  FIG.  1   , the identification and registration system  138  may be a camera system  140  for identifying one or more of any optical signature on the tube holder  114  or sample container  118 , such as its size, its type, a bar code, a QR code, its payload. The barcode and/or QR code may be used to identify the tube holder  114 . However, other systems such as optical sensors and scanners, RFID-reader systems reading a unique RFID of the tube holder  114  or sample container  118  on the tube holder  114  or sensors inside the transport plane  112 , can be used to identify positions and to localize the tube holders  114 . A further option can be high precision GPS, in particular enhanced with Wi-Fi, Bluetooth and/or GSM signals. Any other suitable alternative can be in principle also used. 
       FIG.  2    shows exemplary static queues  141  on the transport plane  112 . The queues in this example may be static queues  141  which are placed such their purpose is fulfilled while minimizing their obstruction with a main traffic of tube holders  114  on the transportation area  126 . As can be seen in  FIG.  2   , the static queues  141  may be placed next to a laboratory station  122  of the laboratory automation system  120 , and, as an example, may be placed on the queue area  128  branching from the transportation area  126  to minimize the obstruction with the main traffic of tube holders  114  on the transportation area  126 . The laboratory station  122  may specifically be configured for picking (denoted by reference number  142 ) and/or placing (denoted by reference number  144 ) tube holders  114  and/or sample containers  118  from the transport plane  112 . 
     In the example shown in  FIG.  2   , the queue area  128  may comprise a sample container output queue  146 , a sample container input queue  148 , an empty tube holder output queue  150 , and an empty tube holder input queue  152 . In the sample container output queue  146 , tube holders  114  with a sample container  118  may be queueing. The sample container output queue  146  may be used to modulate fluctuations in number of sample container  118  arrivals. The sample container output queue  146  may be split into emergency (STAT) samples and routine samples, specifically into a queue of emergency (STAT) samples  154  and a queue of routine samples  156 . Emergency (STAT) samples may be samples with enhanced priority. The queue manager  136  may be configured for calculating the route of a tube holder  114  loaded with a STAT sample so that it can skip part of the sample container output queue  146 . The sample container output queue  146  may be used for continuous supply of sample containers  118  to connected devices, such as to at least one of the laboratory station  122  of the laboratory automation system  120 . 
     The sample container input queue  148  may be configured for storing tube holders  114  with a sample container  118  entering the transport plane  112 . For tube holders  114  in the sample container input queue  148 , the control system  132 , specifically the routing system  134 , may decide their next target considering delays between query and response. The tube holders  114  may be stored in the sample container input queue  148  until their next target is known. The sample container input queue  148  may be a random access queue or a First-IN-First-out queue. Random access queue may be beneficial when long delays for the query occur. 
     The empty tube holder output queue  150  may be configured for providing a constant supply of empty tube holders  150  at a loading position  158  of the transport plane  112  to connected devices, specifically to the laboratory station  122 . The empty tube holder output queue  150  may guarantee constant supply such that connected devices reach their stated throughput. The empty tube holder output queue  150  may have a high capacity since it is not predictable when empty tube holders  114  are needed in connected devices. 
     The empty tube holder input queue  152  may be configured for storing empty tube holder  114  from a transport interface  160  of the distribution system  110  to provide access to the transportation area  126  to travel to its next target. The empty tube holder input queue  152  may have storage capacity in order to account for delays of empty tube holders  114  moving from the empty tube holder input queue  152  to the transportation area  126  when traffic on the transportation area  126  is dense. The empty tube holder input queue  152  may free connected devices, specifically the laboratory station  122 , from empty tube holders  114  in order to not block the connected devices. 
     As shown in  FIG.  2   , each of the queues  146 ,  148 ,  150 ,  152  may comprise a plurality of queue fields  162 . The queue fields  162  may be fields on the transport plane  112 . At least one queue field  162  of the respective queue may be an interface field  164  between the transportation area  126  and the at least one queue area  128 . On the interface field  164 , one field moves may be allowed from and to the interface field  164  on a side of the queue area  128 . For example, a first queue field of the respective output queue  166  and a last queue field of the respective input queue  168  may be interface fields  164 . The routing system  134  and the queue manager  136  may be configured for being aware of movement within the interface fields  164 , specifically of movement of the queueing tube holders  114  within the interface fields  164 . A move of the tube holder  114  inside the respective queue in one direction may be as far ahead as possible without causing any collisions or claiming fields  162  of the transport plane  112  of other tube holders  114 . 
     Additionally, the sample container output queue  146  may comprise an interface field  164  to the STAT queue  154 . The STAT queue  154  may be the sample container output queue  146  with the emergency (STAT) samples. The interface field  164  may be configured for providing an interface to STAT samples to merge into the output queue  146  of the routine samples. Starting from this interface field  164 , the sample container output queue  146  may comprise tube holders  114  with both priorities, STAT samples and routine samples. In case tube holders  114  in the sample container output queue  146  have to be rerouted, it may be possible to route the respective tube holders  114  through the connected devices and/or enter back to the sample container input queue  148  and/or directly retrieve the respective tube holders  114  through a potentially empty STAT queue and/or sample container input queue  148 . 
       FIG.  3    shows exemplary dynamic shared queues  170  on a transport plane  112 . In addition or as an alternative to the static queues  141 , as exemplarily shown in  FIG.  2   , the transport plane  112  may comprise at least one dynamic shared queue  170  having at least one dynamic shared queue field  172 . The routing system  134  may be configured for dynamically assigning the at least one dynamic shared queue field  172  of the dynamic shared queue  170  to every tube holder  114  on the transport plane  112 . The dynamic shared queue  170  may be a random access queue. Tube holders  114  within the dynamic shared queue  170  may be not movable. 
     The dynamic shared queue field  172  may specifically be a queue with capacity of one tube holder  114 , where tube holders  114  can drive on from the transportation area  126  and later drive off again. Tube holders  114  may only drive on the dynamic shared queue field  172  if it is the final target field. The routing system  134  may be configured for assigning all dynamic shared queue fields  172  to a list of forbidden fields such that tube holders  114  can only drive on a dynamic shared queue field  172  if it is its final target field. 
     A location of the at least one dynamic shared queue field  172  on the transport plane  112  may be selected according to the following rules:
         a field of the transport plane  112 , if it does not contain static queues  141  or if it is directly connected to a field with static queues  141 ; and   if there are exactly three neighboring fields physically available.       

     Thus, as highlighted in  FIG.  3    by the circles  174  around corners of the transport plane  112 , fields on the transport plane  112  having only two neighboring fields may be excluded from dynamic shared queues  170  as they may be not reachable. However, the dynamic shared queue  170  may be arranged on an outer lane  176  of the transportation area  126 . The location of the dynamic shared queue fields  172  may be chosen such that its interference with the main traffic on the transportation area  126  is minimal and a high number of dynamic shared queue fields  172  are available in a layout. Outer lanes  176  on the transport plane  112  may be suitable for being assigned as a dynamic shared queue field  172 . 
     LIST OF REFERENCE NUMBERS 
     
         
           110  distribution system 
           112  transport plane 
           114  tube holder 
           116  single tube holder 
           118  sample container 
           120  laboratory automation system 
           122  laboratory station 
           124  sample tube 
           126  transportation area 
           128  queue area 
           130  drive system 
           132  control system 
           134  routing system 
           136  queue manager 
           138  identification or registration system 
           140  camera system 
           141  static queue 
           142  picking tube holders and/or sample containers 
           144  placing tube holders and/or sample containers 
           146  sample container output queue 
           148  sample container input queue 
           150  empty tube holder output queue 
           152  empty tube holder input queue 
           154  queue of emergency (STAT) samples 
           156  queue of routine samples 
           158  loading position 
           160  transport interface 
           162  queue field 
           164  interface field 
           166  first queue field of the respective output queue 
           168  last queue field of the respective input queue 
           170  dynamic shared queue 
           172  dynamic shared queue field 
           174  circle 
           176  outer lane