Note: Descriptions are shown in the official language in which they were submitted.
CA 02795022 2012-09-28
SYSTEM FOR STORING AND TRANSPORTING TRANSPORTING CONTAINERS
System for storing and transporting transport containers or the like of the
generic type
stated in the preamble of claim 1.
There are very many different and diverse designs and constructions of storage
and
transport systems. For example, it is known to equip the aisles of high rack
storage
facilities with rails in each storage level, in order to provide container-
transporting
vehicles which can travel horizontally on these rails. Such solutions are
disclosed e.g.
in DE 39 07 623 A or DE 102 54 647 A to name just a few examples.
Storage systems for removing containers from storage using satellite vehicles
are
disclosed e.g. in DE 10 2007 010 191 Al or DE 20 2007 051 238 Al.
As described in these reference documents, systems of this type require the
sequence, in which the respective containers are stored or discharged, to be
determined in advance, wherein in particular discharge and receiving devices
have to
be provided upstream of the racking systems, in order to provide certain
buffers or
collecting or sorting lines, to name just a few disadvantages of these known
systems.
If the containers in such systems have to negotiate transverse and
longitudinal paths
in order to be discharged or removed, the transfer points of the respective
path
sections require particular machine elements which can transfer the
containers, such
as turning platforms or the like.
Automatic picking storage facilities are confronted with partially conflicting
require-
ments. In addition to efficiency which, where possible, is so high that the
picking
personnel are continuously utilised to capacity, there is a desire for a short
reaction
time within the system expressed as the number of containers taken out of /
placed
into storage per unit of time, i.e. orders should also be processed in the
shortest time
possible after they have been generated. It is also advantageous if the
containers
which have been removed from storage are discharged to the pre-zone in exactly
the
desired sequence, since otherwise sorting must take place, during which the
goods
delivered from the storage facility must be finally sorted either manually or
with
additional technical outlay.
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2
On the one hand, it is known, for the lower range of efficiency, to use
standard racking
serving units having one or several load receiving means, the efficiency of
which,
however, is often not sufficient when a single device is used, multi-aisle
systems are
then installed with correspondingly complex conveyance technology in the pre-
zone of
the racks, on the other hand high-performance-container-storage systems are
known
which operate in accordance with the principle that a plurality of movements
are
performed in parallel with each other, e.g. Sistore (DE 39 07 623) or
Rotastore.
These systems are dependent on the fact that they select their storage-
removal/storage-entry activities from the longest possible list of orders so
that they
1o can optimise their travelling paths and their stops. This is at variance
with the
requirement for a short reaction time. It is likewise not possible to directly
generate
the sequence desired at the picking station. High-performance storage systems
of a
conventional design are distinguished by the fact that relatively complex pre-
zones
are required in order to fulfil the required distribution functions. These pre-
zones are
cost-intensive, require space and after putting into service cannot be adapted
very
effectively, if at all, to changing boundary conditions. A frequent problem is
also the
ability to gain access to such complex conveyance systems in the event of a
malfunction or for maintenance purposes.
The object of the invention is to provide a transport and storage system which
is
highly flexible and can dispense with additional buffer lines, collecting
lines and the
like, as well as with structural elements which change the direction of
container
transportation.
With a storage and transport system of the type stated in the introduction,
this object
is achieved in accordance with the invention by at least one vehicle which is
equipped
with a rail-compatible travelling mechanism and a floor-compatible travelling
mechanism, and by a racking system having rail-mounted and floor-level
travelling
paths for the vehicle. In other words, the vehicles have separate travelling
mecha-
3o nisms for the rail-mounted and floor-level travelling paths.
With a corresponding storage and transport system it is thus possible to use
both
floor-level and rail-mounted travelling paths for the respective vehicles,
which leads to
a series of advantages.
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3
By means of the invention, it is possible to produce e.g. storage systems
which have a
high storage-entry and removal-from-storage efficiency and which function
without
any fixed installation in the pre-zone of the storage facility and at the same
time fulfil
the requirement of short reaction times and correct removal-from-storage
sequence to
a significant extent. The transfer points can be disposed in a flexible manner
and at
any distance from the storage facility. High-performance picking warehouses
are also
possible, in which only a minimum of active mechanical equipment is installed
within
the rack and which are very compact in terms of construction owing to the use
of flat
transverse tunnels also provided in an embodiment of the invention.
Embodiments of the invention are described in the subordinate claims. As
already
indicated briefly above, it can be provided that the racking system is
equipped with
tunnel-like floor travelling paths in particular transversely with respect to
the rail-
mounted travelling paths, wherein the rail-mounted travelling paths form in
particular
the rack aisles of the racking system. In other words, the front longitudinal
beams of
the multi-level racking system support or form the rail-mounted travelling
paths.
This design renders it possible to utilize, by means of the pre-set routes,
which are
generally provided for accessing the rack aisles in the racking unit and are
arranged
transversely with respect thereto, by means of their tunnel-like design, the
air space
above these routes completely from the first rack level as a racking unit,
which results
in a more compact construction whilst maintaining the same storage capacity of
a
racking unit.
As is known per se, in accordance with the invention each vehicle is equipped
with
dedicated load receiving means and in an embodiment is also equipped with a
control
and drive unit linked to a computer, which means that the vehicles can be
moved and
activated completely automatically both on the floor-level and rail-mounted
travelling
paths. Therefore, AGV-functionality (Automated Guided Vehicle System) of the
vehicles is provided.
For the purpose of advancing movement within the rack-rail system and within
the
surface area (on the floor) the vehicle is equipped with two travelling
mechanisms
which on the drive side consist of two motors and associated power
electronics. The
two motors are connected to the right and left drive wheels of the two
travelling
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4
mechanisms by a respective transmission. The motors can rotate independently
of
each other at the same or even different speed. For journeys within the rail
system,
the two motors will always rotate at the same rotational speed. For a journey
on the
floor, identical rotational speeds produce straight-ahead travel, whereas
different
rotational speeds permit cornering ("differential steering").
In accordance with the invention, it is also provided that each vehicle is
equipped with
at least one sensor for detecting obstacles and/or for detecting position
markers.
Detection of obstacles can be performed e.g. by means of so-called laser
scanners
1o which provide the angle and distance of located obstacles.
Fully automatic control procedures can be achieved by means of these sensor
devices. With corresponding positionally fixed sensor markers it is e.g.
possible to
detect the centre of a lane or a preferred lane path by means of the
corresponding
reflection, i.e. in order to permit automatic filtering from floor-level
travel to rail-
mounted travel.
The current position of the vehicle can be determined on the basis of a known
starting
position using coupled navigation algorithms. The information required for
this
purpose relating to the distance travelled and the direction maintained is
obtained by
measuring the revolutions of the two motors. Since on account of various error
influences the current vehicle position, which is calculated in this manner,
has ever
increasing deviations with respect to the real position as the travel distance
increases,
it is not possible by means of this method alone to carry out a longer journey
over the
free surface area to the point of entry into rail system of the racking unit
or a picking
station with sufficient degree of accuracy. In this case, "sufficient" means
that the
vehicle arrives at the centre between the right and left rails with a degree
of accuracy
which is better than about 2cm. A lateral offset (positioning error) in this
order of
magnitude can be compensated for by means of mechanical lead-in chamfers,
whereas larger deviations could result in the vehicle becoming stuck at the
entrance
or suffering mechanical damage. For this reason, at the end of a journey,
i.e., at a
distance of ca. 3 metres from the destination (e.g. entry into the rail
system), a switch
is made to a different - more accurate - relative locating method: with the
aid of a laser
scanner which is mounted on the end side of the vehicle, two reflector markers
which
are mounted on the left- and right-hand side directly next to the entrance to
the rails
CA 02795022 2012-09-28
are detected and their position relative to the vehicle is measured. From
these
measured values, which change constantly as the vehicle continues to move
closer to
the entrance, it is possible by means of suitable evaluation algorithms to
perform a
journey all the way to the centre of the entrance with a sufficient degree of
accuracy.
5
The distinctiveness of the method resides in the fact that, although the
measured
values of the laser sensor do not have the level of accuracy required for the
task,
skilled filtering of the measured values and fusion of the sensor measured
values with
the - likewise error-prone - movement information of the vehicle, which is
based upon
1o the measurement of the wheel revolutions, facilitate a sufficiently precise
determina-
tion of position.
Therefore in general terms, as the vehicle drives onto the rail, i.e., upon a
change
from the floor-compatible travelling mechanism to the rail-compatible
travelling
mechanism, it is possible to obtain position information, which is
sufficiently accurate
for the task, by means of suitable filter algorithms from in principle error-
prone
measured values of the path measurement and distance measurement devices,
which
means that the vehicle can drive onto said rail without becoming damaged.
It is apparent that the invention can ensure that the sequence of removed
transport
containers for final discharge and/or for sorting can also be random, since
the control
options of the floor-level and rail-mounted vehicles render it possible to
effect a
change in sequence without any problems, i.e., by overtaking a vehicle which
is in
front of a vehicle at a rear position in the sorting system.
In accordance with the invention, it is also provided that with an identical
drive a drive
is effected such that the speed of the journey performed on rails is greater
than the
speed of the journey conducted on the floor. The steering kinematics can be
achieved e.g. by means of differential steering, wherein in accordance with
the
invention other options are of course also incorporated.
The supply of power is effected via power accumulators which are charged
during
travel in the racking unit via contact lines or in a contactless manner, e.g.
by means of
an inductive power transfer system, wherein other solutions are also possible,
e.g.
boost-charging at individual start-up positions or accumulator-change systems.
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The rail-compatible travelling mechanism permits not only direct serving of
racking
systems, rail-mounted sections can also be integrated into the travel route,
in order to
be able to cover individual distances e.g. at a higher speed or else in order
to travel
from rack sections to spatially separate rack sections, i.e., via suspended
rails, which
means that such rail systems can run at a corresponding height over e.g.
sections of a
production area which are located on the floor. It is thus possible e.g. to
create a
traffic system without any intersections, in that unused spaces above
production
plants are utilised or else in order to connect spatially separate rack
sections via
suspended rails. This type of rail system can also run at a corresponding
height over
sections of production areas which are located on the floor.
In order to move the vehicles to a different location, racking serving units
or
lift/distribution carriages can also be provided in the racking aisles or at
corresponding
locations. The vehicles are therefore vehicles which in each case serve only
one level
or individual racking bays in the racking unit from the rails. If required,
they change
levels by means of the aforementioned lifts which can be located at any
position.
These vehicles are also known as satellite vehicles.
In an expedient manner, at least two tunnel regions are provided within a
racking unit
in order to permit a circulating operation without two-way traffic. The
tunnels can be
designed to be very flat in accordance with the constructional height of the
vehicles
and can be of such a width that not only can buffer sections be formed in
front of and
behind the lifts, which means that by reason of the directed flow of the
vehicles the
lifts are used in double-cycle, i.e., while a vehicle coming from upper
racking levels
departs from the lift in the lower lift position, a vehicle wishing to travel
upwards
moves at the same time onto the lifting table on the other side. This enables
the lifts
to achieve high throughput rates.
The tunnels can also be designed in such a way that the aforementioned
overtaking of
the vehicles is possible, in order thus to be able to effect a certain amount
of sorting at
the same time.
In order to load and unload the transport vehicles, a transfer device can be
provided
which is allocated in particular to the rail-compatible travelling mechanism
of the
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7
vehicle and is adapted thereto. In other words, the load receiving means of
the
vehicles is used in the rail operation, since an accurate definition of the
vehicle with
respect to the transfer location is then possible.
Further features, details and advantages of the invention are apparent from
the
description hereinafter and with reference to the drawings, in which:
Figure 1 shows a top view of a part of a storage facility with vehicles
travelling on the
floor,
Figure 2 shows a side view taken approximately along line II-II in Figure 1,
Figure 3 shows an enlarged illustration of a transport vehicle in a three-
dimensional
illustration prior to filtering into a rail system,
Figure 4 shows a three-dimensional bottom view of the transport vehicle,
Figure 5 shows an enlarged filtering region for the vehicles from floor-level
travel to
rail-mounted travel, and
Figure 6 shows a load-changing station for loading and unloading the vehicle,
and
Figure 7 shows a further embodiment during the filtering procedure.
The storage and transport system which is designated in general by the
reference
numeral 1 is formed substantially by a racking unit, e.g. a high racking unit,
which is
designated in general by the reference numeral 2 and which is loaded by
vehicles
designated by the reference numeral 3, wherein in the top view in accordance
with
Figure 1 the vehicles designated by the reference numeral 3 use the floor
level as a
travel level, whereas the vehicles designated by the reference numeral 3a are
positioned so that they can travel in the rail system of the racking unit 2.
The vehicles 3 thus travel in the racking unit 2 itself on rails on the
respective level in
order to supply and remove products to and from the racking bays located on
this
level, whereas for travel on the floor they travel on the ground. To this end,
they have
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8
separate travelling mechanisms.
It is apparent that the vehicles on the floor surface can also overtake one
another (see
vehicles 3b and 3c in Figure 1 above). The racking system 2 has inter alia
tunnel-like
floor-level travelling paths, designated in general by the reference numeral
4, as well
as rail-mounted travelling paths, designated in general by the reference
numeral 5,
wherein the rail-mounted travelling paths 5 provide access to the racking
locations 6
in the racking unit for the containers which are transported on the vehicles
and are
designated in general by the reference numeral 7.
As shown in Figure 2, the floor-level, tunnel-like travelling paths 4 render
it possible
for the air space located thereabove having further racking locations 6 to be
used for
receiving the corresponding containers 7.
Located at some preferred locations, into which rail-mounted travelling paths
are
integrated, are lift systems which are designated by the reference numeral 8
and
enable the vehicles to change levels.
Details of the vehicles 3 are indicated in Figures 3 and 4. For example, the
wheels 9
provided for travel on rails and the wheels 10 and 1 Oa provided for floor-
level travel
and separate therefrom, wherein in this case the common drives are not
illustrated in
greater detail.
Figures 3 and 4 also illustrate load receiving means 11 which are indicated
merely
symbolically and which render it possible to receive the containers 7, either
empty or
filled, and to deposit them in the racking locations 6 or at another location.
Figure 3 also indicates rails 5a of the rail-mounted travel regions as well as
lateral
guide wheels 12, in order to facilitate filtering and travel on the rails.
The slightly enlarged illustration of Figure 5, as an extract of Figure 1,
indicates that
the vehicles 3 are equipped with sensors 13 which can detect e.g. reflective,
positionally fixed control markers 14 and 14a, in order to reach the centre
position of a
rail-mounted travel lane, designated in Figure 5 by the reference numeral 15,
between
these markers by means of a corresponding computing operation.
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The control computers of the vehicles 3 having sensors 13 providing data for
filtering
purposes can also be used to provide other controls, which means that the
floor-level
travel of the vehicles can also be established accordingly via calculated
virtual
travelling paths (lanes). By means of these sensors, it is also possible to
determine
the distances between individual vehicles next to one another and in front of
one
another, which is illustrated by dotted lines in Figure 5, wherein the beams
which
determine the target point are designated by the reference numeral 16.
In the variant shown in Figure 7, the current position of the vehicles 3' is
determined
on the basis of a known starting position S (cf. direction of travel arrow in
Figure 7)
using coupled navigation algorithms. The information required for this purpose
relating to the distance travelled (cf. direction of travel arrow in Figure 7)
and the
direction maintained is obtained by measuring the revolutions of the two
motors of the
floor-compatible travelling mechanism or of the wheels 10 and 1 Oa.
Since on account of various error influences the current vehicle position,
which is
calculated in this manner, has ever increasing deviations with respect to the
real
position as the travel path increases, it is not possible by means of this
method alone
to carry out a longer journey over the free surface area to the point of entry
into the
rail system 5 of the racking unit 2 or a picking station or load-changing
station (cf.
Figure 6) with a sufficient degree of accuracy. In this case, "sufficient"
means that the
vehicle arrives at the centre between the right and left rails with a degree
of accuracy
which is better than about 2cm. A lateral offset (positioning error) in this
order of
magnitude can be compensated for by means of mechanical lead-in chamfers (cf.
Figure 3), whereas larger deviations could result in the vehicle becoming
stuck in the
entrance during filtering into the racking aisle 15 or when driving to the
rail ends 5a at
this location, or in the vehicle suffering mechanical damage.
3o For this reason, at the end of a journey, i.e., at a distance of ca. 3
metres in front of
the entrance into the rail system 5 or the racking aisle 15 (or another
corresponding
destination) a switch is made to another - more precise - relative locating
method.
With the aid of a laser scanner 21 which is mounted on the end side of the
vehicle 3'
and which "monitors" the region (shaded in Figure 7) in front of the vehicle,
two
CA 02795022 2012-09-28
reflector markers 14, 14A, which are mounted on the left- and right-hand side
directly
next to the entrance to the rails are detected and their position relative to
the vehicle
3' is measured. The laser scanner 21 provides the control computer of the
vehicles
with the angle and distance of obstacles, in this case the reflector markers
14, 14A.
5 From these measured values, which change constantly as the vehicle 3'
continues to
move closer to the entrance of the racking aisle 15, a journey is conducted,
by means
of suitable evaluation algorithms, all the way to the centre of the entrance
(indicated
by a dot-dash line) with a sufficient degree of accuracy.
10 The laser scanner 21 can also be used to detect and drive round obstacles.
The
obstacles can appear unexpectedly in particular during floor-level travel,
since e.g.
persons or further vehicles can move on the ground.
Figure 6 illustrates one possible load-changing station 20, in order to load
the vehicles
3 with corresponding containers 7' or in order to receive containers 7
therefrom.
Positioned within a frame 18 is a double lift 17, wherein in the illustrated
example the
right-hand part of the double lift is designated by the reference numeral 17
and the
left-hand part is designated by the reference numeral 17a. Connected to the
upper lift
positions of the lift 17 or the lift 17a, are roller conveyors 19 and 19a,
wherein the front
roller conveyor 19 on the right-hand side in Figure 6 is inclined so as to
descend
towards the lift 17, whereas the slightly more highly positioned rear roller
conveyor
19a is inclined so as to descend to a sorting and loading region 21 such that
the
containers designated by the reference numeral 7' can run off to the left,
whereas the
containers designated by the reference numeral 7 can run off to the right in
the
illustrated example.
In the respectively lower position, the lifts 17 and 17a are aligned with the
loading
region of the vehicle 3, so that containers 7 can be discharged and containers
7' can
be received respectively.
At this juncture, it should be noted that the station illustrated in this case
can also be
designed in a different manner. The illustrated example represents an option
for
integration into the existing rail system with the running rails 5a for the
vehicles 3
which are then rail-mounted.
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11
Of course, the described exemplified embodiment of the invention can also be
modified in many respects, without departing from the basic idea.
