The invention relates to methods of managing a warehouse
with a plurality of autonomously controlled transport devices for
Transportation and storage of storage objects, the transport devices
by means of locally based position determining means their position
during driving and when storing storage objects
determine and communicate to a central office.
efficient management, especially large stock provides
a significant logistical problem dar
Increased efficiency in this area a high potential for savings
For companies. Modern warehouse management systems are therefore
usually computerized, using a variety of procedures
to optimize complex processes, such as the assignment of
Orders for storage and retrieval of storage objects
individual transport devices, position detection and storage
stored objects, error monitoring, etc. are known.
Concept of "warehouse" is within the scope of the present description
far to understand and includes both classic shelf storage, at
which storage objects are provided for this purpose and the storage location
storage devices, as well as open space storage,
where the storage objects themselves define the storage location by their position.
Also, the term in the local context includes both camps in closed
or semi-closed buildings, as well as open air storage.
Concept of "transport device" is also widely understood
and concerns any type of device that is suitable to the position
of a warehouse object within the warehouse.
However, the present description refers only to autonomous
controlled transport devices, d. H. those whose individual
Movement actions on locally made decisions
based on local conditions
the basis for all parties agreed and valid
Rules are taken. A classic example of such
Autonomically controlled transport device is one of a human
Driver controlled forklift.
From the DE 199 38 345 C1
a generic warehouse management method is known. Individual orders are created by a central office, in particular a central computer, and communicated via radio communication to individual forklifts of a forklift fleet. The concrete rules of the order creation and award, which are not the subject of the present invention are based, inter alia, significantly on the fact that the headquarters has knowledge of the respective whereabouts of the individual forklifts of the fleet. Since, as explained above, it is autonomously controlled stacker, the position determination has to be carried out at least partially locally and communicated to the control center.
the aforementioned document is the position determination by
the so-called "coupling" known. When coupling, starting from
a known reference point, all movements of the truck
vectorially detected by means of suitable, local sensors and the
each current position as a vector sum from the reference point
calculated. This results in the problem that the errors,
which attach to each individual sensor measurement, when determining the position
Add up so that increases with distance from the reference point
Setting a growing error that quickly scales
The expansion of the storage objects can achieve, so a reliable retrieval
stored objects is no longer possible. The named
This paper addresses this problem with a sporadic update of the
Points of reference, in particular whenever the truck has one of
a plurality of predetermined fixed points for the stacker
are clearly marked, happens. Each time passing a
Such fixed point this becomes the new reference point of the truck,
so that the coupling error is reset with each update
In this method, the high computational or communication effort.
In order to obtain sufficient accuracy, i. H. in particular an accuracy
in the centimeter range, to achieve a variety
performed by highly accurate sensor measurements and with each other
be combined. If this is done locally in the stacker this must be with
be equipped with a data processing device of high capacity,
which is especially at large fleets with adverse costs
connected is. On the other hand, the calculation on the central computer
Relocate, a variety of sensor data to the central computer
and the determined positions are communicated back to the forklifts
become. This requires especially for high accuracy requirements
the position determination a considerable radio traffic volume. There
anyway already by the order communication between forklifts
and headquarters a relatively high volume of radio traffic unavoidable
is the system through the positioning radio communication
additionally loaded and must be correspondingly larger
be interpreted, which in turn leads to disadvantageous additional costs.
To avoid the above-mentioned disadvantages of the coupling method, GPS-based positioning systems are known. Special receivers of the forklifts receive signals from satellites of the Global Positioning System (GPS) and detect them from this their position through trilateration. However, the GPS typically does not provide sufficient resolution, so the accuracy of position determinations required for efficient inventory management is not achieved. In addition, the GPS signals in closed buildings are difficult or impossible to receive.
From the DE 197 20 828 B4
For example, a method is known which addresses these problems by occupying an area to be detected with a multiplicity of permanently installed, stationary transceivers which communicate with corresponding mobile, local transceivers at the objects to be located. At regular intervals, the local transceiver communicates with selected stationary transceivers and performs distance measurements thereon. The position is determined on the basis of trilateration or according to the principle of hyperbolic or pseudorange detection. This system, which is disclosed in the cited document for monitoring aircraft on an airfield, is suitable for constantly monitoring the aircraft positions with a constant accuracy which does not have to be better than several meters. A detection in the centimeter range is not required because the fine positioning, z. B. when docking at terminals, is done manually by the air and ground staff and due to the predefined, immutable position of the terminals no need for centimeter accurate position detection by the center exists.
Although this system would also be applicable to warehouse management.
However, it should be clear in terms of accuracy
be improved, resulting in more frequent communication
between mobile and stationary transceivers and communication
the resulting location results could be achieved at the headquarters.
However, this would lead to a considerable amount of radio traffic
lead, which brings the above-mentioned disadvantages.
is the object of the present invention, a generic
Warehouse management system to improve such that the disadvantages
of the prior art are overcome and that in particular
the computing or radio traffic volume can be reduced.
Task is combined with the features of the preamble of
Claim 1 achieved in that the position determination
when storing with a higher accuracy than during
of the driving operation.
The basic idea
The invention is the accuracy of the position determination needs
to vary. While driving, z. From forklifts,
is an exact knowledge of the position by the headquarters not required
because steering, acceleration and deceleration decisions
be made locally by the autonomously acting driver. The position knowledge
through the central office is necessary only insofar as this (rough)
Position when creating new storage or removal orders
must be used. On the other hand, when storing storage objects
a very precise knowledge of the position required because of this position
corresponds to the storage location of the storage object and to retrieval
the object must be approached very accurately again. this applies
especially for bearings without defining the storage locations
Device, such as fixed shelves. By use of the present invention can
the computing or radio traffic during the comparatively
long periods of driving can be reduced significantly without the
Accuracy of position determination at the relevant times
Basically, it does not matter which specific system is used to determine the position. Advantageously, however, the positioning means of each transport device comprise a local transceiver and the position determination by means of radio communication takes place between the local and a plurality of stationary reference transceivers. Such a kind of position determination is basically from the above already cited DE 197 20 828 B4
However, although advantageous developments of the technical design, in particular the position determination with different accuracies, will be explained in more detail below.
An application of the present invention to that of DE 197 20 828 B4
known system has a non-optimized aspect. Unlike the airfields disclosed in the cited document, the area of a typical warehouse is not necessarily static. On the contrary, typical bearings "breathe" during the day or season, depending on production cycles or cyclical conditions. This means that at certain times a much larger storage area is required than at other times. With the known system, this phenomenon can only be counteracted by illuminating the maximum possible storage area with a sufficient number of stationary reference transceivers. This leads to considerable investment costs, with some of the stationary transceivers being used at peak times at most.
A development of the present invention therefore provides that the local transceivers of at least some transport devices in their idle state serve as reference transceivers for other transport devices. This can reduce the number of stationary transceivers to a mini mum - in the best case on two transceivers - be reduced. If a local transceiver has determined its position relative to the stationary transceivers, communicates with the control center and is in a dormant state, eg. During a paging or paging operation, additional transport devices may be instructed to determine their own position using this dormant, local transceiver as the new reference transceiver. In this way, the storage area equipped with reference transceivers can be expanded or reduced as required, in particular as required.
is provided that before a release of a local transceiver
as a reference transceiver, a positioning of the transceiver
carrying transport device with high accuracy, d. H. With
one against the position determinations during
the driving increased accuracy occurs. Is, as preferred,
a local transceiver during a putaway process
Released as a reference transceiver, its position is as above
already explained, already detected with high accuracy.
However, cases are also conceivable in which the exact
Position determination specifically for the purpose of release as a reference transceiver
already indicated, the position determination is preferably carried out
by distance determination based on distance measurements between the
local and multiple reference transceivers and subsequent
Trilateration. Such a procedure typically requires
at least three ("tri") distance measurements. In the present case
However, as explained in more detail below,
also two distance measurements be sufficient. It is advantageously
applied a method in which any distance measurement by emitting
a radio spectrum through the local transceiver, receiving the
emitted spectrum through a reference transceiver, retransmission
of the received spectrum by the reference transceiver, Re-receiving
the re-transmitted spectrum through the local transceiver
and determining the distance between the local and reference transceivers
by comparing the emitted spectrum with the received spectrum
he follows. Is the time delay in receiving and re-sending the
Radio signal known by the reference transceiver, lets go through
Analysis of the sent and received by the local transceiver
Spectrum to determine the distance to the reference transceiver very accurately.
By determining the distance to several reference transceivers
the position of the local transceiver can be determined. The
Setting the accuracy of the position determination is preferably carried out
by selecting the number of used for position determination
Reference transceiver. This means, among other things, that the radio traffic
between local and reference transceivers for a rough one
Position determination, as during driving, clearly
is less than for a precise position determination, for example
when storing storage objects and / or before releasing a
local transceivers as a reference transceiver.
is in the headquarters based on positions and recorded locally
Lanes that are communicated by the transport devices,
an actual road network of the camp reconstructed to compare with
to recognize a predetermined target road network warehouse management error. Especially
the position data collected by the transport devices during
of the driving operation and communicated to the control center,
In the synopsis they represent those ways that
the transport devices in the fulfillment of their orders
typically driving along. Will the data be a variety of
Transport devices summarized, for example, by
an appropriate averaging can be done results in an actual road network
high accuracy, although the individual position data used to
Structure of road network information contribute, a comparatively low accuracy
to have. Especially with an open space warehouse without permanently installed
Storage devices, the road network is not structurally predetermined, but
results from the actually realized storage locations and
can change over time. By constant regular
or sporadic comparison of positional data by individual
Transport devices are transmitted with the like
above explained statistically reconstructed road network
to recognize changes easily. These changes
can either be from intended changes
in the structure of the warehouse or by errors. As a cause of the error
come z. B. Disturbance of position determination, Add
new or removal of known objects or accidental shifts
of storage objects and thus of storage locations in question. Although allowed
the described measure is not the immediate recognition
the cause of the error; but it leads to very rapid detection
the mistake itself and thus opens up the possibility
a timely investigation and correction.
As already mentioned, an important part of a warehouse management system is to store the specific storage locations centrally. In connection with the present invention, it is proposed to be advantageous to store the positions determined during the storage of storage objects in an inventory file. Although the position determination in many cases does not capture the actual position of the storage object but rather the position of the transport device. When using a fleet However, preferably identical transport devices can be closed from the position of the transport device readily to the precise storage location.
will be in the inventory file in addition to the items
also the respective storage objects individualizing data stored.
This can preferably take place in that data which the
Individualize storage objects, based on the transport devices
recorded by markings of the storage objects and communicated to headquarters
become. This can be used to build an inventory file that
for each individual storage object can specify exactly which concrete
Storage location is assigned to the object. This is especially important
if, unlike, for example, only generically distinguishable
Stock objects, an individually different treatment of
Stock objects is required.
were only three situations in which position data to the
Central transmitted, distinguished, namely
during storage of storage objects, while driving
and before releasing a local transceiver as a reference transceiver,
the latter case overlapping with the former
can. In an advantageous embodiment of the invention is further
provided that when outsourcing storage objects the respective
Position of the transport device determined with high accuracy
and communicated to the central office. This has, especially in
Connecting to an inventory file has the advantage of being recognized
of errors a position that determines when an object is swapped out
was used in the inventory file when storing the same warehouse object
stored position can be compared. Communicated position deviations
between the storage and the removal of the same storage object
can either be based on errors of positioning or
indicate unintentional movement of storage objects. In
In any case, such error detection allows a fast
Intervention and, if necessary, a correction of the error or an adjustment
of the system, in particular the inventory file, to changed conditions.
it can be seen that the communication between transport devices
and the central office an essential feature of modern warehouse management systems
in general and that of the present invention in particular
is. An error or a collapse of the communication could
have fatal consequences for the entire administrative system.
In a further development of the invention is therefore intended
that positions determined by a transport device
before communication to the control center temporarily in a local
Memory of the transport device can be cached.
This means that in case of communication problems between transport devices
and headquarters, the z. B. by a temporarily particularly high
Radio traffic may be conditional, positional data
stored locally and at a later date, though
For example, a low radio traffic volume prevails at
the control center can be communicated. This allows one
"smaller" interpretation of the communication system, then with a
largely constant utilization can be operated. This
is advantageous compared to a "large" designed communication system,
this is very low with high load peaks and long phases
Utilization is operated.
The previous ones were storage objects and transport devices always
treated as separate terms. In the context of the invention, however, is intended
also be aware of the possibility that the
Warehouse objects with the transporters structural units
form. As an example serve here the new car warehouse of an automobile manufacturer.
Here the storage objects, namely new cars, form their own
own transport device, so that the case of a structural
Unit between storage object and transport device is given.
The for carrying out the invention
Method required position determining means can
fixed or reversible in or on the transporters / storage objects
Features and advantages of the invention will become apparent from the following,
special description and the drawings.
1 : a simplistic, schematic representation of a position determination with minimized number of reference transceivers.
2 : A highly simplified, schematic representation of a position determination using a local transceiver as a reference transceiver.
3 : a highly simplified, schematic representation of positional determinations of different accuracy.
4 : a simplistic, schematic representation of the flexible extension of a storage area.
1 shows in a highly simplified, schematic representation of a storage area 10 , at whose in 1 lower edge 10a a first stationary transceiver 12 and at their in 1 left edge 10b a second stationary transceiver 14 are installed. The transceivers 12 and 14 are set up to receive and transmit a transmitted radio spectrum. In this case, the spectrum can in each case be embedded in a more complex signal, which contains, for example, identification codes for identifying or addressing transmitters and / or receivers. With the help of such identification codes, it is possible to operate the transceiver 12 . 14 to reduce to cases where they are addressed individually. In this way, the radio traffic can be compared to cases where the transceivers 12 . 14 receive and retransmit each receivable radio signal, be significantly reduced. It should be noted that an identification code can also be realized by the specific structure of the spectrum, ie, for example, the relative distribution of its frequencies.
On the storage area 10 is still a forklift 16 shown. Note that for purposes of this specific part of the description, the term "stackers" is used for illustrative purposes only. This is not intended in any way to limit the generality of the present invention, which relates to any type of autonomously controlled transport devices. The truck 16 can get along in 1 not shown transport roads over the storage area 10 move and also in 1 Store stored items not shown at predetermined locations or outsource from there. The truck 16 is equipped with a local transceiver which is substantially equivalent to the previously discussed stationary transceivers 12 and 14 works, in contrast to these, however, with the truck 16 over the storage area 10 emotional.
To perform a position determination sends the transceiver of the truck 16 one radio signal each to the stationary transceiver, which always operates as a reference transceiver 12 . 14 and receives their re-transmitted signal. By comparing the transmitted and received again signal can be a local processing unit in the truck 16 the current distances of the truck 16 to the reference transceiver 12 and the reference transceiver 14 determine. This distance information is for an unambiguous position determination of the truck 16 unsatisfactory. Rather, one would be at the connection line 18 the stationary transceiver 12 . 14 mirrored position 16 ' give the same distance measurements. However, if the calculating system has suitable additional information, such as. B. the expansion of the storage area 10 , in the case shown, the theoretical position 16 ' , in the 1 dashed lines are discarded, so that the position of the truck 16 can be done clearly. This variant of the known trilateration method, which typically requires three distance measurements, reduces the number of stationary transceivers to a minimum, which brings significant cost advantages.
2 shows the same scenario as 1 with an additional stacker 20 , The truck 20 is located approximately on the connecting line 18 the stationary transceiver 12 . 14 so that a position determination according to the simplified trilateration method explained above is not possible since both possible positions lie within the permissible area, so that no unambiguous position determination can be made on the basis of only two distance measurements. To the position of the truck 20 Nevertheless, the dormant forklift becomes still to be determined 16 whose position was previously according to 1 was determined to be used as an additional reference transceiver. To determine its position, the truck communicates 20 with the reference transceivers 12 . 14 . 16 in the manner described above, thus performing a "true" trilateration procedure.
Note that the representations of the 1 and 2 - As well as the following figures - not only in terms of the geometry of the bearing surface 10 are greatly simplified, but in particular for the sake of clarity, only an unrealistically small number of forklifts show. Typically, on the storage area 10 a whole fleet of several 10 to several 100 trucks or vehicles on the road, each of which can be used in their dormant state after a position determination as a (temporary) reference transceiver for determining the position of other forklifts. The decisions as to which stacker serves as reference transceiver for which other stackers at which time are made by a computer-aided control center, which also communicates these decisions to the relevant stackers.
As an example, assume that a stacker receives a specific deposit order. Together with the order, he receives the order to make himself available at the storage location as a reference transceiver for other forklifts. These are preferably forklifts that are in the vicinity of the notified storage location and require positioning at the time of storage. These are preferably transmitted an identifier of the intended as a reference transceiver truck so that they can connect with their position determination with this. In a typical scenario with a large number of stackers, it is realistic to assume that the majority of the position determination without the involvement of stationary transceivers 12 . 14 he follows. Rather, one or more trilateration calculations (with or without the use of additional geometric information) can be carried out to determine the position. There in the accuracy of the position determination by the number of carried out distance determinations, ie in particular the number used for determining position reference transceiver, be increased.
3 shows in a highly simplified, schematic representation of the principle of the demand-based variation of the accuracy of position determinations to optimize the overall system. In the illustration shown, the bearing surface 10 several separate rows of warehouses 22a - 22e , between which transport routes 24a -F, on which forklifts can move, are created. In 3 are the schematics of two position determinations of a stacker 26 shown at different times.
For the example of 3 Let's assume that more forklifts 28 . 30 . 32 with warehousing work on the warehouse rows 22a respectively. 22e are busy and are there in a dormant state, with their position of the headquarters is known. Next, suppose that the dormant forklift 28 . 30 . 32 have been given the command to provide their local transceiver as a reference transceiver. At a first time (in 3 shown by solid lines) is the stacker 26 while driving, what by the movement arrow 34 is indicated. During driving, it is not necessary for the control panel to be informed of the stacker position with high accuracy, since it does not control the truck operation 26 has to take over. This is rather controlled autonomously by a driver who from the central office a specific order, eg. B. the collection of a special stored goods from the stock row 22e had received. Nevertheless, it is necessary for efficient warehouse management that the head office is at least roughly informed about the positions of moving forklifts. Therefore, the truck performs 26 during the driving operation, a trilateration measurement, whereby he the stationary transceiver 14 as well as the temporary reference transceivers of the stackers 28 and 30 for determining the position. Their ID and position had previously been submitted to him by the headquarters.
At a second time (in 3 shown in dashed lines) has the truck 26 his mission goal, namely a predetermined storage location in the storage row 22e reaches and goes into the dormant state to perform the arranged storage work. At this time, a precise position determination makes sense. On the one hand, the autonomously used storage location can be compared with the storage location registered in an inventory file, deviations indicating errors. On the other hand, the dormant forklift 26 serve as a reference transceiver for other trucks. However, his position must be known exactly. Consequently, at this time, highly accurate positioning is performed, except for the transceivers 14 . 28 and 30 also the stationary transceiver 12 and the temporary reference transceiver 32 to increase measurement accuracy. These transceivers were the forklift 26 preferably previously referred to by the center as to be addressed reference transceiver.
4 shows in a highly simplified schematic representation of the possibility of flexible expansion of the storage area 10 , It is assumed the storage area 10 should be over its edges 10a and 10b beyond the extension area 10 ' be extended. As additional difficulty be assumed, the extension area 10 ' wise a radio communication restricting barrier 34 , z. As a wall or a building, on. Finally, assume the position of a stationary truck 36 in the original storage area 10 be the headquarters known exactly. If the central office now requires a forklift 38 to a storage location in the extension area 10 ' The difficulty may arise that the forklift 38 can not or not accurately determine its position at the given storage location due to lack of communication with reference transceivers. In the example shown is about the communication between the truck 38 and the stationary transceiver 12 ' (dash-dotted line) through the barrier 34 with special needs. To remedy this situation, the head office therefore sends another stacker 40 into an area of the extension area 10 ' , in which a precise position determination - in the example by distance measurement to the stationary transceivers 12 . 14 and the temporary reference transceiver 36 - can be determined with sufficient accuracy. Preferably, this posting is associated with a specific warehouse order. At the given place, the stacker 40 available as a reference transceiver. The truck 38 now finds with the stationary transceiver 14 as well as the temporary reference transceivers 36 and 40 a sufficient number of reference transceivers to determine its position.
In this example as well, it should be expressly noted that the advantages of the system manifest themselves above all in the case of a large number of forklifts or vehicles, and the representation of 4 and the associated description represent an actually unrealistic oversimplification for purely illustrative purposes.
Of course, the embodiments discussed in the specific description and shown in the figures represent only illustrative embodiments of the present invention. Those skilled in the art will appreciate from the disclosure herein Tes Variation spectrum given. In particular, the special technique of the distance measurements can be modified as needed. Nor is it necessary that the transport devices are stackers in the strict sense. Rather, the possibility should also be recognized that transport devices and laboratory objects form structural units. Further improvements of the system, for example, in an individual marking of storage objects, their capture by the truck and their use by the control center, z. B. in an inventory file, may exist, of course, also be realized. Finally, the further use of the determined position data is not limited to the use described in the examples. In particular, the position data can be used to detect actual travel paths of the forklifts and to compare them with a desired route network which, for example, corresponds to an actual route network thus detected at an earlier point in time.
QUOTES INCLUDE IN THE DESCRIPTION
The documents listed by the applicant have been automated
generated and is solely for better information
recorded by the reader. The list is not part of the German
Patent or utility model application. The DPMA takes over
no liability for any errors or omissions.
Cited patent literature
- - DE 19938345 C1 
- - DE 19720828 B4 [0009, 0014, 0015]