DE102014219933A1 - Method for controlling a material flow system - Google Patents

Abstract

The invention relates to a method for controlling a material flow system (110), the material flow system having modules (112) for transporting product packages (114, 118, 128) and the modules (112) autonomously communicating with one another in the material flow system (110). Here, the transport of each goods package (114, 118, 128) along a material flow path (116, 132) from a start module (120, 130) by means of transport steps to a destination module (122, 134), wherein each transport step of a particular commodity package (114, 118 , 128) comprises an outbound transport from a first participating module (112) and an inbound transport to a second participating module (112). According to the invention, each transport step of the particular goods package (114, 118, 128) is provided with a discrete time stamp and the goods packages (114, 118, 128) are transported in such a way that successive transport steps increase monotonically for each particular goods package (114, 118, 128) Accept values for the timestamp and that for each participating module (112), the outbound transport of a first specific commodity packet (114, 118) has a lower value, and only in the case of a tandem transport has the same value for the timestamp as the value for the timestamp for a subsequent incoming transport of a second specific merchandise package (114, 128).

Description

Field of the invention

The invention relates to a method for controlling a material flow system, the material flow system having modules adapted for transporting packages of goods, a computer program adapted to perform the steps of the method, an electronic storage medium on which the computer program is stored is, and an electronic control unit with the electronic storage medium.

State of the art

More recent developments, such as electronic commerce or the increasing individualization of products, require the introduction of complex material flow systems, in particular in order to be able to meet the increased requirements in the area of intralogistics. It is therefore desirable to have material flow systems which can be adapted as flexibly as possible to changing conditions without thereby sacrificing efficiency. Basic tasks which should be fulfilled by such material flow systems in the field of intralogistics include, in particular, the transport, assembly, sorting and buffering of product packages, in particular so-called "plug and work" material flow systems, which have a decentralized control of the individual modules, being used. to allow a flexible adaptation of the material flow system to the changing conditions.

Such a material flow system is the so-called "FlexConveyor", which, for example, from the DE 10 2008 059 529 A1 is known. It comprises a decentrally controllable material flow system, which has a plurality of preferably identical modules for transporting packages of goods, wherein the individual modules can be easily assembled or detached from one another in order to be able to provide a material flow system that corresponds to the respective requirements. The material flow system described therein allows the transport of packages of goods along a material flow path, starting from a start module by means of transport steps to a destination module. Here, each module of the material flow system can serve as a start or target module, so that the proposed material flow system under decentralized control complex transport tasks with a variety of goods packages, which can be promoted from different start modules to different target modules. Other material flow systems are in DE 10 2009 031 137 A1 and DE 10 2009 033 600 A1 disclosed.

Zaezilia Seibold, Thomas Stoll and Kai Furmans, Layout-optimized sorting of goods with decentralized controlled conveyor modules, Systems Conference (SysCon), 2013, IEEE International, p. 628-633, 2013 , describe in addition to the above-mentioned "FlexConveyor" another material flow system, which is also known under the name "GridSorter". In this case, the so-called "grid sorter" comprises, in particular, an area of modules that is as coherent as possible, which are preferably arranged in a rectangular shape. Because of this arrangement, the size and shape of the material flow system and the positions of start modules and target modules are freely selectable within wide limits, this device has a high degree of flexibility to adapt to the particular requirements and conditions of their use, especially in intralogistics. The "GridSorter" has a continuous process of independent layout recognition running in the background, which is primarily designed to detect possible layout changes, for example due to failures of individual modules.

In addition to preventing collisions between different commodity packages being transported at the same time in the material flow system, control in the material flow system should be arranged to avoid so-called "deadlocks", where the term deadlock describes a state of the commodity package in which the goods package is within a loop in the material flow system and therefore can not get to the desired destination module. According to Stephan H. Mayer, Development of a Completely Decentralized Control System for Modular Continuous Transferors, Scientific Reports of the Institute for Materials Handling and Logistics Systems of the Institute for Materials Handling and Logistics University of Karlsruhe (TH), volume 73, publisher Prof. Dr.-Ing. Kai Furmans, University of Karlsruhe, 2009, Chapter 4.2.3, pages 69-75 can be reduced by reserving the entire material flow path from the start module to the destination module before the actual shipment of the commodity packet in the associated material flow system. In this dissertation it is examined to what extent a discrete reservation of modules could be advantageous. In this case, each participating module would only be reserved for a specific time window in which the arrival of the goods package would be expected. A deadlock situation could be avoided by making a reservation for each participating module from the start module to the destination module for specific time windows. However, the author does not pursue this approach further, since he assumes that in case that several packages of goods are present in the material flow system at the same time, it estimates the probability as very high that the expected arrival times due to mutual interference of the goods packages at interfaces can not be guaranteed and therefore the time windows would have to be repeatedly postponed. In particular, to avoid deadlock situations, he assumes that the modules would be forced to permanently adjust their time windows to the actual arrival times and, accordingly, to update the already made reservations. This would considerably increase the computation time and data transfer effort required to do so, thereby raising significant concerns about the scalability of the material flow system controlled in this way.

Object of the invention

Proceeding from this, the object of the present invention is to provide a method for controlling a material flow system, wherein the material flow system has modules for transporting packages of goods, which at least partially overcomes the disadvantages and limitations of the prior art. In particular, the method should be able to set up the control of the material flow system such that the above-mentioned problems and restrictions do not occur during operation of the material flow system as far as possible. In particular, the inventive method should allow the most efficient and deadlock-free control of material flow, which is set up so that a synchronization of the modules is as little susceptible to interference, to allow for longer periods a coordinated flow of goods packages over the entire material flow system. In addition, a computer program that is set up to perform the steps of the method, an electronic storage medium on which the computer program is stored, and an electronic control unit with the electronic storage medium are to be provided.

Disclosure of the invention

This object is achieved by a method for controlling a material flow system, a computer program, an electronic storage medium and an electronic control unit having the features of the independent patent claims. Advantageous developments, which can be implemented individually or in any combination, are shown in the dependent claims.

Hereinafter, the terms "having", "having", "including" or "including" or any grammatical variations thereof are used in a non-exclusive manner. Accordingly, these terms may refer to situations in which, in addition to the features introduced by these terms, there are no other features or to situations in which one or more other features are present. For example, the expression "A has B", "A has B", "A includes B" or "A includes B" can both refer to the situation in which, apart from B, there is no further element in A. (ie a situation in which A consists exclusively of B), as well as the situation in which, in addition to B, one or more further elements in A are present, for example element C, elements C and D or even further elements ,

It is further to be understood that the terms "at least one" and "one or more" and grammatical variations of these terms, when used and to be used in connection with one or more elements or features, are intended to provide the element or feature in a single or multiple way can usually be used only once, for example, at the first introduction of the feature or element. In a subsequent re-mention of the feature or element, the corresponding term "at least one" or "one or more" is generally no longer used, without limiting the possibility that the feature or element may be provided once or more than once.

Furthermore, the terms "preferably", "in particular", "for example" or similar terms are used below in connection with optional features, without restricting alternative embodiments thereof. Thus, features introduced by these terms are optional features, and it is not intended by these features to limit the scope of the claims and, in particular, the independent claims. Thus, as those skilled in the art will recognize, the invention may be practiced using other embodiments. Similarly, features introduced by "in one embodiment of the invention" or by "in one embodiment of the invention" are to be understood as optional features without, however, being construed as limiting alternative embodiments or the scope of the independent claims. Furthermore, these introductory expressions are intended to combine all possibilities of combining the features thus introduced with other features optional or non-optional features, remain untouched.

The present invention thus relates to a method for controlling a material flow system, wherein the material flow system has modules for transporting packages of goods. Here, the term "module" or "conveyor module" means a device within the material flow system, which is equipped to receive within a transport step, a specific package of goods (so-called "incoming transport") and after a certain time to deliver the particular package again ( so-called "outgoing transport"). In order to fulfill this task, each module is connected to at least one neighboring module, wherein the connection is configured such that the goods package is transported within the transport step from the considered module to the neighboring module or from the neighboring module to the module under consideration.

In a preferred embodiment, in this case, the module is set up in such a way that it can perform so-called "tandem transport" (English batch batching). The term "tandem transport" is here understood to mean a transport carried out by the module in which the same module within the same time window emits a package of goods, i. perform an outbound transport, and can accept a merchandise package, i. can carry out an incoming transport. The tandem transport can in this case in particular be such that within the time window, a first goods package on a first side of the considered module, which performs the tandem transport is delivered to a neighboring module and within the same time window on a second, in particular the first side opposite arranged second side of Module considered a second commodity package, which is provided by another neighbor module can be accepted. In particular, the tandem transport has a considerable advantage that the module in question can still receive a second package of goods within one and the same time window after delivery of the first package, without the module in question having to remain unoccupied for an intervening period of time.

In order to be able to fulfill the tasks assigned to it, the module can have, on the one hand, actuators for transporting the product packages and, on the other hand, sensors for identifying packages of goods. In particular, each module can have its own controller, which can both control the transport of each package of goods that takes place via the relevant module, as well as edit requests and, based on an assessment of the requests, can make appropriate decisions. For this purpose, the modules of the material flow system autonomously communicate with each other, an embodiment is preferred in which a module concerned can communicate as directly as possible with all its associated neighboring modules as possible. In this way, on the one hand to dispense with a central communication point and on the other hand required for the communication within the material flow system technical effort to be minimized.

The term "material flow system" means a device which allows the transport of packages of goods via individual modules, which has the material flow system. In this case, the individual modules can be combined in any form, with each module having at least one neighboring module. For this purpose, there are three types of modules in the material flow system, which can differ in their function, without having to have a different technical structure as a result. The transport of each package of goods takes place here along a material flow path, starting from a "start module" or "source module", at which a goods package provided for transport enters the material flow system. The goods package then in the material flow system is finally transported along the material flow path to a "destination module" at which the goods package leaves the material flow system again after the transport has taken place. The remaining modules of the material flow system, which have neither the function of the start module nor the function of the target module, are arranged between the at least one start module and the at least one target module of the material flow system and are also referred to as "conveyor modules" because of their suitability for transporting the product packages. A topology of the material flow system resulting from said modules and their relative spatial arrangement in the material flow system can be recorded in a so-called "adjacency matrix". In this case, each module of the material flow system can obtain the topology of the material flow system through communication with the neighboring modules and in this way create the adjacency matrix itself.

In a particularly preferred embodiment, the modules of the material flow system are each configured such that their surface arranged for transport have a rectangular shape, preferably a square or approximately square shape. In particular, this type of embodiment, the modules can be arranged in the material flow system such that it is possible to transport packages of goods, starting from a particular module, in three or four directions. Here, the so-called "GridSorter" is designed such that in it equipped modules form a dense, cohesive network, which may be in the form of a two-dimensional matrix of conveyor modules, designed. In this way, the "GridSorter" can have a comparatively high degree of flexibility, in particular because the material flow path of a particular commodity package can be determined in a variety of ways. In particular, by controlling the material flow system according to the method according to the invention, it is possible to use the area formed by the modules for transporting goods as efficiently as possible in order in this way, the transport steps for each goods package within a shortest possible time, in a robust manner and especially under avoidance of deadlocks. Here, the term "robust" refers to a property of controlling the material flow system in which a number of occurrence of defects in the material flow system is as small as possible.

The present method of controlling the material flow system is suitable for transporting a variety of types of commodity packages. These include unpackaged goods, goods provided with a packaging and / or an outer packaging and / or goods, which are arranged individually or together with other goods unpacked, packed and / or repackaged on a substrate, such as a pallet. In particular in order to facilitate the recognition of the product packages, it is advantageous if the product package has an identification, for example in the form of a one- or two-dimensional code, for example a barcode or a data matrix code. Other suitable codes include QR Codes, Electronic Data Interchange (EDI) Codes, Radio Frequency Identification (RF ID) Codes, Serial Shipping Container Codes (SSCC), or other markings. In particular, in order to ensure that the goods package arrives from the selected start module to the desired destination module, the modules provided at least for this function, preferably arranged at the edge of the material flow system, can have a communication with an external system, wherein the external system can be set up for this purpose to specify the start module and the destination module for the relevant transport of the selected goods package.

• 1. Aufeinanderfolgende Transportschritte eines bestimmten Warenpaketes weisen monoton steigende Werte für den Zeitstempel auf. Somit besitzt der Wert eines ersten Zeitstempels für einen ersten Transportschritt einen geringeren Wert als der zweite Zeitstempel für einen zweiten, späteren Transportschritt desselben Warenpakets.
• 2. Der ausgehende Transport eines ersten bestimmten Warenpakets auf einem beteiligten Modul weist höchstens denselben Wert für den Zeitstempel auf wie der Wert für den Zeitstempel für einen darauffolgend eingehenden Transport eines zweiten bestimmten Warenpakets. Hierbei kann der Zeitstempel für den ausgehenden Transport des ersten bestimmten Warenpakets auf dem beteiligten Modul jedoch nur dann denselben Wert für den Zeitstempel des darauffolgend eingehenden Transport des zweiten bestimmten Warenpakets auf demselben Modul aufweisen, wenn das Modul den oben beschriebenen Tandemtransport für die beiden Warenpakete bereitstellen kann. Sollte dies nicht der Fall sein, ist es erforderlich, dass der ausgehende Transport eines ersten bestimmten Warenpakets auf dem beteiligten Modul einen geringeren Wert für den Zeitstempel, das heißt einen früheren Zeitstempel, aufweist, wie der Wert für den Zeitstempel des darauffolgend eingehenden Transport eines zweiten bestimmten Warenpakets auf demselben Modul.

As already described, each transport step of a particular merchandise package comprises an outbound transport from a first module involved in the respective transport and an inbound transport of the particular merchandise package to a second module also involved in the respective transport. According to the invention, each transport step of the specific goods package is provided with a discrete time stamp. Here, each incoming transport as well as each outgoing transport can be referred to as an "event", which is thus provided with one of the discrete time stamps. The term "timestamp" is understood to mean a relationship between the transport step and a follower of a monotonically increasing sequence. As a monotonically increasing sequence, the sequence of natural numbers 1, 2, 3, ... can be used; however, basically all monotonically increasing sequences are suitable for this purpose, as long as a particular sequence term of the sequence has a higher value compared to a preceding sequence term of the sequence. It is also irrelevant for the choice of numbers, whether they belong to the decimal system or another number system, such as the hexadecimal system. Accordingly, the discrete time stamp is an arbitrary numerical value whose absolute value is irrelevant, whereby the respective value of the time stamp can be used to produce a partial order in a distributed system, such as the material flow system of individual modules herein. That from Leslie Lamport, Time, Clocks and the Ordering of Events in a Distributed System, Communications of the ACM 21.7, pages 558-565, 1978 , presented concept of so-called "logical clocks" is able to introduce a partial time sequence of events in a distributed system, without the physical time prevailing in this system, which externally by a time measurement in seconds, fractions or multiples thereof must be used. Based on this, each module in the material flow system has a logical clock, wherein the logical clock can be understood as a counter which can only move forward, that is, can only take on a value which represents the value already present in the counter for the logical clock Clock exceeds. Thus, the counter hereby provides a monotonically increasing sequence which can be used to coordinate the above-described events, that is the outgoing transports and the incoming transports during a transport step from one module to an adjacent module. According to the invention, therefore, is set up so that the logical clock of each module can proceed with each event that has occurred. In this case, it is not necessary for each time step provided with a specific time stamp to have the same length since the logical clock remains decoupled from the physical time. The method according to the invention only provides that the transport of the product packages takes place in such a way that the following two conditions are met:

• 1. Successive transport steps of a particular commodity package have monotonically increasing values for the timestamp. Thus, the value of a first time stamp for a first transport step has a lower value than the second timestamp for a second, later transport step of the same commodity package.
• 2. The outbound transport of a first specific commodity packet on a participating module has at most the same value for the timestamp as the value for the timestamp for a subsequent incoming transport of a second particular commodity packet. In this case, however, the timestamp for the outgoing transport of the first specific merchandise package on the participating module can only have the same value for the timestamp of the subsequent incoming transport of the second specific merchandise package on the same module if the module can provide the tandem transport described above for the two merchandise packages , If this is not the case, it is necessary that the outbound transport of a first particular commodity packet on the participating module has a lower value for the timestamp, that is, an earlier timestamp, such as the value for the timestamp of the subsequent incoming transport of a second timestamp certain package of goods on the same module.

The logical clock in each module thus precedes each event that has occurred, with the events relating to a respective module occurring in the order determined by their timestamps. As already mentioned, it is not necessary here for each time step, which has a specific time stamp, to have the same length. Rather, it is ensured by the method according to the invention that each event, that is to say each outgoing transport from a first participating module and every incoming transport to a second participating module, is executed in the order partially determined according to the relative values of the time stamps. This may in particular be independent of a physical time, i. it is not necessary for a module to specify the timing of the events in physical units, that is, in seconds, fractions or multiples thereof. Rather, the method according to the invention enables complete decoupling of the sequence of events in the material flow system defined by the time stamp, which can also be referred to as logical time, from an external physical time predetermined by physical processes. In this way it becomes possible to avoid the otherwise particularly complex necessary coordination effort between the logical time in the material flow system and the physical time outside the material flow system. The material flow system working with the method according to the invention defines itself quasi its internal discrete, logical time, which, independent of an externally prevailing physical time, controls the events within the material flow system.

In a particularly preferred embodiment of the method according to the invention, as soon as a goods package enters the material flow system, a reservation process for the particular goods package for the entire material flow path from the start module to the destination module takes place, after completion of the reservation process the transport of each goods package along the material flow path in a transport process can be carried out from individual transport steps. In particular, in this case, the transport of the specific package of goods can be carried out until the specific package of goods is located at the destination module. In the event that a goods package enters the material handling system on an empty startup module, the startup module may start the reservation process, in particular by sending a reservation request to a neighbor module of the startup module. The reservation request can then be forwarded by the neighboring modules to further modules which are likely to be involved, preferably in the direction of the intended destination module. The reservation request can thus be forwarded by the participating modules in such a way, until the reservation request has reached the destination module. If the destination module also sends an acknowledgment to the reservation request, the confirmation can preferably be routed back to the start module together with the individual confirmations of the modules involved in the total reserved material flow path.

In a particularly preferred embodiment, the reservation of the participating modules for the individual transport steps can be made for the particular goods package intended for transport by reserving a value for the timestamp of the transport step for each particular transport step. In this case, the lowest value for the time stamp is reserved, which firstly exceeds the value for the last reserved time stamp for a preceding transport and for which, on the other hand, there is no reservation for the module involved in this transport step. By the first condition that the lowest, not yet assigned value for the time stamp is reserved, the order of the individual transport steps for the particular goods package can be determined in this way. The second condition, that only one value for the time stamp is reserved, for which the module involved in this transport step has not yet assigned any other reservation, ensures that no collision can occur between two goods packages whose material flow path runs over the same module. In this way, the reservation of a particular module with timestamps for incoming transport and for outbound transport only for time windows that have a time stamp for which there is no reservation is present. The logical clock present in the participating module, which also has a time stamp, can hereby ensure that no reservation is made for a time window which is related to the time stamps of the partial order in the material flow system in the past. This advantageous condition reflects the partial order of the order of the individual transports of the product packages introduced by the method according to the invention into the control of the material flow system.

However, it may be advantageous if the startup module not only posts a single reservation request, but initiates at least two different reservation requests and selects one of the possible material flow paths through the material flow system by a subsequent evaluation of the reservation request acknowledgments. In this case, it may be advantageous to include in the evaluation whether a waiting time on one of the modules occurs along a specific material flow path and whether the waiting time can possibly be shortened by presetting the time stamp of the associated transport step. The term "waiting time" on one of the modules is understood to mean a time window in which the logical clock of the participating module increases, but the goods packet remains on the specific module without an outgoing transport to a neighboring module occurring in the relevant time window. From this it follows that a certain material flow path, taking into account the waiting times, can receive a changed assessment. However, due to the order only partially present in the material flow system, it may be the case that there may be a gap between a lower value for the timestamp of an inbound transport to a particular module and the higher value for the logical clock of the particular module Module within the gap has no further reservations. In this case, the time stamp of the relevant event can be set to the value of the logical clock of the associated conveyor module and the reservation for the transport of the specific goods package without waiting time.

As soon as the above-described confirmation of the reservation request finally arrives at the start module again, the start module can begin the transport process for the particular goods package. Accordingly, the transport of the particular package of goods can take place after the reservation for the particular package has been made for at least part of the material flow path, preferably for the entire material flow path, from the start module to the destination module. As already mentioned, it can be particularly advantageous if the transport method for a goods package, which comprises carrying out all transport steps from the start module to the destination module, can take place as soon as possible after receiving the reservation confirmation and, if applicable, after carrying out the evaluation of at least two reservation confirmations , In this case, the transport of the goods packages can preferably be carried out in such a way that in each case the transport step which has the lowest value for the time stamp is first executed. By virtue of the above relationship between the value for the timestamp and an associated monotonic sequence, this can ensure that the transport of the commodity package is in the reserved order in the material flow system. This is important insofar as, as is customary in practice, more than one package of goods is to be transported on the same material flow system over the same time windows. A transport of the specific goods package which has actually taken place along the reserved material flow path can in this case increase the logical clock of the participating modules to the value of the time stamps for the actual transport steps that have actually taken place. In this way, the logical time in the material flow system can be adjusted according to the order of the already processed transport steps and in this way enable further transport steps for further product packages. In this case, the involved module only executes an incoming transport step for a specific goods package if no transport step is provided for another goods package before, that is, with a lower value for the time stamp.

The method according to the invention makes it possible to set a partial sequence of all transport steps on the entire material flow system through the entirety of the reservation methods for all the packages of goods. As already mentioned, the order of all transport steps is therefore only partial, because preferably only there an order of the transport steps is determined, where the material flow paths of two product packages overlap. In the transport method preferably following the reservation procedure, the transport steps are then processed in accordance with the specified partial sequence. For this purpose, before each transport step from a first module to a second module between the first module and the second module, a communication to release the relevant transport step take place. In addition, this communication can also be used to be able to take into account any sources of error that may occur in the material flow system, for example due to the failure of a module or due to the fact that a goods package has been left on a specific module.

In another aspect, the present invention includes a computer program which is set up to perform the steps of the method according to the invention. The present invention also relates here to an electronic storage medium on which such a computer program is stored. Finally, the present invention also relates to an electronic control unit which has an electronic storage medium on which such a computer program is stored.

For the operation of the "grid sorter", a time-window-based reservation method has been developed according to the invention, each module reserving only a specific time window for a specific goods package along the intended material flow path. In this way, the "GridSorter" determines an order for the shipments of the individual goods packages whose compliance requires a synchronization of the individual modules of the material flow system with each other. After confirmation of the reservation, the transport of the specific goods package takes place on the material flow path, wherein the involved modules autonomously synchronize with each other for the execution of this task.

In particular, the method according to the invention can increase the performance and robustness of the control of a material flow system with bidirectionally used modules for transporting packages of goods. In particular, the method according to the invention enables the extensive exclusion of so-called deadlocks already in the reservation process and in the subsequent transport process of a commodity package. Here, waiting times in the reservation process can be taken into account. Because of the partial order of the sequence of the individual transport steps introduced by the logical time, the method according to the invention is robust to fluctuations in the transport time actually occurring in the relevant material flow system for a specific goods package along a concrete material flow path. In addition, the method of the invention may allow for possible inclusion of tandem transports. The autonomous communication of the individual modules in the material flow system has a manageable communication effort during the reservation process and a limited, only locally required communication effort during the transport process. An additional synchronization of the shipments of the product packages in the entire material flow system is automatically established in the present method and therefore does not require any additional communication between the individual modules of the material flow system.

The inventive method thus allows the reservation of material flow paths for certain time windows, for which the individual modules must have a common understanding of time. According to the invention, the synchronization is no longer bound to the physical time, whereby the communication effort can be significantly reduced and a susceptibility to interference due to stochastic influences on the scheduled timings can be omitted. Rather, according to the invention, the entire material flow system is synchronized on the basis of logical time, which uses the event structure of the transports of the product packages via the modules of the material flow system. For this purpose, it is sufficient if the synchronization of the modules in the material flow system is limited to those modules that are each involved in a particular transport, which is significantly reduced in particular during the transport process, the communication effort.

Brief description of the figures

Further details and features of the present invention will become apparent from the following description of preferred embodiments, in particular in conjunction with the dependent claims. In this case, the respective features can be implemented on their own or in combination with one another. The invention is not limited to the embodiments. The embodiments are shown schematically in the figures. The same reference numerals in the individual figures designate the same or functionally identical or with respect to their functions corresponding elements.

In detail show:

1 a schematic representation of a first embodiment of a reservation method in the method according to the invention for controlling a material flow system;

2 a schematic representation of a first embodiment of a transport method in the method according to the invention for controlling a material flow system;

3 a schematic representation of a second embodiment of a reservation method in the method according to the invention for controlling a material flow system; and

4 a schematic representation of a second embodiment of a transport method in the method according to the invention for controlling a material flow system.

Description of the embodiments

In the 1 to 4 is in each case schematically a particular aspect of the invention Method for controlling a material flow system 110 shown. In all of these embodiments, the material flow system has 110 about modules 112 , which in each case to a transport of goods packages 114 are set up.

1 schematically represents with the steps a) to d) a first embodiment of a reservation method. To make reservations, the modules communicate 112 of the material flow system 110 autonomous with each other to exchange reservation messages, including in particular reservation requests, reservation rejections and reservation confirmations. The start and destination modules of the goods packages are arranged in this example so that a tandem transport is not useful.

1a) shows by way of example a first material flow path 116 which is for a first goods package 118 that comes from a first boot module 120 to a first target module 122 is already reserved. The reserved route for the first material flow path 116 In this case has three transport steps, each of the three transport steps with a discrete time stamp, here "1", "2" and "3", is provided. The first transport step for which the first time stamp "1" was reserved leads here from the first start module 120 to a first neighbor module 124 and includes both outgoing transport of the first commodity package 118 from the first boot module 120 as well as an incoming transport to the first neighbor module 124 , In an analogous manner, the transport step takes place with the time stamp "2" from the first neighbor module 124 to the second neighbor module 126 and thus includes an outbound transport from the first neighbor module 124 and an incoming transport to the second neighbor module 126 , In a likewise analogous manner, the third transport step with the discrete time stamp "3" comprises the transport of the goods package 118 from the second neighbor module 126 to the first target module 122 and thus has an outgoing transport from the second neighbor module 126 and an inbound transport to the first destination module 122 on.

In the present embodiments, a natural number 1, 2, 3, ... was selected for the numeral stamp of each transport step. However, it is readily possible to use any other sequence of numbers as long as it has monotonically increasing sequence terms. As already mentioned, it is irrelevant whether the selected numbers belong to the decimal system, the hexadecimal system or any other number system. Rather, it is important that the reservation for the first material flow path 116 , as in 1a) shown, for successive transport steps monotonically increasing values for the time stamp. By choosing the in 1a) displayed values for the time stamp of the first material flow path 116 will ensure that for the first package of goods 118 the outgoing transport in each of the participating modules 120 . 122 . 124 . 126 has a higher timestamp than the respective incoming transport.

Continue trying in 1a) now a second package of goods 128 , which is in a second start module 130 located, a second material flow path 132 to a second target module 134 to reserve. For this purpose, it starts a reservation request with the time stamp "1" to the adjacent thereto second neighbor module 126 , The second neighbor module 126 However, there is already a reservation request through the first goods package 118 before, which has the time stamp "2". The goods package 128 can not timestamp "2" to the destination module 134 tandem transport can only be carried out on opposite sides. Consequently, as in 1a) shown, for the reservation request with the time stamp "1" no reservation confirmation.

Rather, communicates according to 1b) the second neighbor module 126 the second start module 130 in that a reservation confirmation is possible at the earliest for the time stamp "4". The time stamp "3" is omitted, since in this situation, no tandem transport is possible and therefore the time stamp "3" already for the outbound transport of the first goods package 118 from the second neighbor module 126 is reserved.

Now, as in 1c) schematically illustrated, a new reservation request of the second start module 130 to the second neighbor module 126 for a time slot with the time stamp "4", this reservation request is evaluated positively, whereupon the second neighbor module 126 another reservation request for the time window "5" to the adjacent second target module 134 can make, which as in 1d) sketched, can also be evaluated positively, which then the second material flow path 132 for the second package of goods 128 from the second startup module 130 over the second neighbor module 126 to the second destination module 134 can be confirmed. The second material flow path 132 here comprises two transport steps, namely the transport step with the time stamp "4" with an outgoing transport from the second start module 130 and an inbound transport to the second neighbor module 126 and the transport step with the time stamp "5" with an outgoing transport from the second neighbor module 126 and an inbound transport to the second destination module 134 ,

In 2 is now schematically the transport method for the goods packages 114 about the modules 112 of the material flow system 110 in accordance with the reservations of the first embodiment in 1 shown schematically. The transport through the modules 112 takes place according to the in 1 schematically illustrated reservation for the material flow paths 116 . 132 , wherein each transport step of the goods packages 114 is made in the order of their discrete timestamps.

According to 2a) are initially the first goods package 118 on the first start module 120 while the second goods package 128 on the second start module 130 is arranged.

In 2 B) is shown as the first boot module 120 the transport step of the first commodity package 118 with the timestamp "1", which queries the outgoing transport from the first start module 120 and the incoming transport to the first neighbor module 124 includes. In parallel, the second start module asks 130 the transport step of the goods package 128 with the time stamp "4" from the second start module 130 to the second neighbor module 126 at. However, this is the responsibility of the second neighbor module 126 no release to the second start module 130 because the second neighbor module 126 there must be a first reservation with the timestamp "2" for the inbound transport and with the timestamp "3" for the outbound transport, which must be performed beforehand. Due to the lack of release remains the second start module 130 in a wait until it, as in 2f) shown schematically, from the second neighbor module 126 the information gets transmitted that the logical clock of the second neighbor module 126 now set to the timestamp "4".

Consequently, according to 2c) only the transport of the first goods package in the time window with the time stamp "1" from the first start module 120 to the first neighbor module 124 , In an analogous manner is according to 2d) during the time window with the time stamp "2" only the first goods package 118 from the first neighbor module 124 to the second neighbor module 126 transported. Likewise, according to 2e) in the time window with the time stamp "3" exclusively the transport of the first goods package 118 from the second neighbor module 126 to the first target module 112 ,

As in 2f) shown schematically, is at the end of the time window with the time stamp "3" the first commodity package 118 in the destination module 122 arrived and has thus achieved his goal. In the subsequent time window with the time stamp "4" informs the second neighbor module 126 now the second start module 130 in that for the following time window "4" an incoming transport of the second goods package 128 from the second start module 130 is expected. This transport step with the time stamp "4", shown schematically, in 2g) instead of.

The final transport of the second goods package 128 from the second neighbor module 126 to the second destination module 134 is schematic in 2h) shown. After completion of the time window with the time stamp "5" thus both goods packages 118 . 128 from their respective startup modules 120 . 130 to their respective target modules 122 . 134 transported without a collision of the two product packages 118 . 128 occurred. Rather, the time stamps issued by the control system made it possible to partially determine the transport order of the product packages 114 in the material flow system 110 within certain time windows in which the modules 112 of the material flow system 110 each had free transport. The logical clocks of the modules remain in the time stamp of the last executed transport step.

In the 3 and 4 schematically is a second embodiment of the inventive method for controlling the material flow system 110 represented, in which by the arrangement of the modules 112 tandem transport 136 are meaningful.

3 shows the reservation process in a schematic representation. According to 3a) Here was the first material flow path 116 for the first goods package 118 , starting from the first start module 120 about the neighboring modules 124 . 126 . 138 to the second destination module 122 for the time windows "1" to "4" already reserved.

Because the goods packages 118 and 130 can be transported in the same direction, this can be the second neighbor module 126 accept a reservation for the transport step with the timestamp "1" because, as in 3b) is shown schematically, the tandem transport 136 such that for the second neighbor module 126 within the same time window with the time stamp "2" at the same time an outgoing transport from the second neighbor module 126 to a third neighbor module 138 and an incoming transport from the first neighbor module 124 to the second neighbor module 126 can be done.

Because of this, as in 3c) shown schematically, a fourth neighbor module 140 to the time window with the time stamp "3" an incoming transport from the third neighbor module 138 Reservations.

Thus, as in 3d) shown schematically, the first material flow path 116 for the first goods package 118 from the first boot module 120 to the first target module 122 and the second material flow path 122 for the second package of goods 128 from the second startup module 130 to the second destination module 134 within the time slots with the time stamps from "1" to "4". The use of tandem transport makes this possible 136 a considerably faster transport of the two packages of goods 118 . 128 ,

4 finally shows the implementation of the transport process for the material flow system 110 in accordance with the reservations of the second embodiment in 3 , the tandem transports 136 include.

4a) schematically shows the transport requests of the first start module 120 for the first goods package 118 to the first neighbor module 124 and the second start module 130 for the second package of goods 128 to the second neighbor module 126 , each in the time window with the time stamp "1". Since neither the first neighbor module 124 still the second neighbor module 126 a reservation with a time stamp lower than "1", the respective transport request can be confirmed.

As in 4b) shown schematically, takes place during the time window with the time stamp "1" the transport of the first commodity package 118 from the first start module to the first neighbor module 124 and at the same time, that is to say within the same time window with the time stamp "1", the transport of the second goods package 128 from the second startup module 130 to the second neighbor module 126 ,

4c) now shows schematically an example of the tandem transport 136 , In the time window with the time stamp "2", both the first goods package 118 from the first neighbor module 124 to the second neighbor module 126 as well as the second package of goods 128 from the second neighbor module 126 to the third neighbor module 138 transported. The tandem transport 136 here denotes the fact that in the second neighbor module 126 in the time window with the time stamp "2" at the same time an outgoing transport of the second commodity package 128 and a detailed transport of the first goods package 118 can be done.

Another tandem transport 136 is in 4d) shown schematically. In this case, in the time window with the time stamp "3" both an outgoing transport of the second commodity package 128 from the third neighbor module 138 as well as a detailed transport of the first goods package 118 in the third neighbor module 138 ,

In 4e) is finally shown how the two packages of goods 118 . 128 their respective target modules 122 . 134 reach, with which the intended transport process is completed.

LIST OF REFERENCE NUMBERS

110

 Material Flow System

112

 module

114

 goods package

116

 first material flow path

118

 first goods package

120

 first start module

122

 first target module

124

 first neighbor module

126

 second neighbor module

128

 second goods package

130

 second start module

132

 second material flow path

134

 second target module

136

 tandem transport

138

 third neighbor module

140

 fourth neighbor module

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008059529 A1 [0003]
• DE 102009031137 A1 [0003]
• DE 102009033600 A1 [0003]

Cited non-patent literature

• Zaezilia Seibold, Thomas Stoll and Kai Furmans, Layout-optimized sorting of goods with decentralized controlled conveyor modules, Systems Conference (SysCon), 2013, IEEE International, pp. 628-633, 2013 [0004]
• University of Karlsruhe (TH), volume 73, publisher Prof. Dr.-Ing. Kai Furmans, University of Karlsruhe, 2009, Chapter 4.2.3, pages 69-75 [0005]
• Leslie Lamport, Time, Clocks and the Ordering of Events in a Distributed System, Communications of the ACM 21.7, pages 558-565, 1978 [0017]

Claims (11)

Method for controlling a material flow system ( 110 ), whereby the material flow system has modules ( 112 ) on the transport of packages of goods ( 114 . 118 . 128 ), whereby the modules ( 112 ) in the material flow system ( 110 ) autonomously communicate with each other, whereby the transport of each package of goods ( 114 . 118 . 128 ) along a material flow path ( 116 . 132 ) from a startup module ( 120 . 130 ) by means of transport steps to a destination module ( 122 . 134 ), whereby each transport step of a particular commodity package ( 114 . 118 . 128 ) an outbound transport from a first participating module ( 112 ) and an inbound transport to a second participating module ( 112 ), each transport step of the particular package of goods ( 114 . 118 . 128 ) is provided with a discrete time stamp and the transport of the goods packages ( 114 . 118 . 128 ) is carried out in such a way that for each particular package of goods ( 114 . 118 . 128 ) successive transport steps assume monotonically increasing values for the time stamp and that for each participating module ( 112 ) the outgoing transport of a first specific package of goods ( 114 . 118 ) has at most the same value for the time stamp as the value for the time stamp for a subsequent incoming transport of a second specific goods package ( 114 . 128 ). Method according to the preceding claim, wherein the transport of the goods packages ( 114 . 118 . 128 ) is carried out in such a way that for each participating module ( 112 ) the outgoing transport of the first specific package of goods ( 114 . 118 ) has the same value for the time stamp as the value for the time stamp for the subsequent incoming transport of the second specific goods package ( 114 . 128 ), if the module has a tandem transport ( 136 ) for the first specific package of goods ( 114 . 118 ) and the second specific package of goods ( 114 . 128 ). Method according to one of the preceding claims, wherein for the particular goods package ( 114 . 118 . 128 ) a reservation of participating modules ( 112 ) for the transport steps is carried out by reserving for a particular transport step the lowest value for time stamps which exceeds the value of the current time stamp and which has not yet been allocated to the modules involved in this transport step ( 112 ) is reserved for another package of goods. Process according to the preceding claim, wherein the material flow path ( 116 . 132 ) for the transport of the specified package of goods ( 114 . 118 . 128 ) is selected by evaluating the reservation requests, including in the evaluation whether a waiting time for at least one of the modules ( 112 ) and whether the waiting time can be shortened by setting the time stamp. Method according to one of the two preceding claims, wherein the transport of the particular goods package ( 114 . 118 . 128 ) after the specific package of goods ( 114 . 118 . 128 ) the reservation for at least part of the material flow path ( 116 . 132 ) from the start module ( 120 . 130 ) to the target module ( 122 . 134 ) is done. Method according to one of the preceding claims, wherein the transport of the goods packages ( 114 . 118 . 128 ) takes place in such a way that the transport step which has a lower value for the time stamp is executed first. Method according to one of the preceding claims, wherein each module ( 112 ) is associated with a logical clock, wherein a completed transport step of the particular commodity package ( 114 . 118 . 128 ) causes the logical clock of the participating module ( 112 ) is set to the value of the time stamp of the completed transport step, whereupon the module ( 112 ) executes only that transport step which has a lowest value for the time stamp which is higher than the value of the logical clock of the participating module ( 112 ). Method according to one of the preceding claims, wherein the transport of the particular goods package ( 114 . 118 . 128 ) until the particular package of goods ( 114 . 118 . 128 ) at the destination module ( 122 . 134 ) is located. Computer program adapted to perform the steps of the method of any one of the preceding claims. An electronic storage medium on which a computer program according to the preceding claim is stored. An electronic control device comprising an electronic storage medium according to the preceding claim.

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