Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Background and Summary of the Invention
The present invention relates to a storage and retrieval
system and in particular to an improved system design that
maximizes the use of available storage space and provides
increased materials handling flexibility.
In the vast majority of storage warehouses, much of
the total available storage space within the facility is either
not used or is used in an inefficient manner. Moreover, in
storage facilities where a greater percentage of the available
space is utilized, the material is usually stored in a manner
that makes access to some of the material extremely difficult.
This, of course, increases the cost of storage and often leads
to problems of lost or misplaced material. Unfortunately, too
often the "solution" for such inefficiency is not the improve-
ment of the existing facility, but rather the construction of
additional facilities.
Many different types of automated storage and retrieval
systems have been proposed to improve the overall operating
efficiency of storage facilities. The semi-automated systems
initially proposed still required a substantial amount of hand
labor, and therefore were subject to the disadvantages inherent
in the use of manual labor. However, the continued reliance
upon manual labor also provided these systems with a great
deal of flexibility. As the more sophisticated fully automated
systems were developed, the efficiency of the storage facilities
improved, but the flexibility of the systems suffered. For
example, the development of the present generation storage and
retrieval machine in combination with the more advanced types
of rack structures currently being used greatly improved
storage efficiency. However, a storage and retrieval machine
operating between two rows of racks can transport material
retrieved from the racks only as far as the ends of the aisle.
Consequently, in some prior art systems, all material
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processing was t~pically conducted on a single conveyor posi-
~ioned transversely to the racks at the end of the aisle. In an
effort to improve upon this system, a "carousel" arrangement of
conveyors at the end of the aisle was proposed so that more
than one load of material could be accommodated in the process
area at a given time. However, the flexibility of this system
was still limited and the congestion problems caused by the
necessity of having to perform all of the shipping, receiving,
and machining operations in a single area remained.
Thus, it is the primary object of the present invention
to provide a storage system that combines the efficiency of a
fully automated system with the operating flexib.ility of a
manual system. More particularly, the system is adapted to
receive incoming material at a receiving area where the material
can be unloaded by an overhead crane and placed into empty
cassettes on conveyors positioned adjacent the first row of
storage racks. From there, the loaded cassettes are moved off
the conveyors and into the adjoining rack bays. The storage
and retrieval machine located on the opposite side of the first
row of racks then retrieves the loaded cassettes and stores
them in the designated bin locations under the control of the
main control center. Similarly, when a cassette is to be
retrieved from a rack and placed on a conveyor, it is passed
back through the first row of racks. Thus, since material
processing is no longer conducted at the ends of the aisle,
it is possible to provide as many loading and shipping con-
veyors as necessary to efficiently handle incoming and outgoing
material.
Ir~ a~dition, special double conveyors are provided to
service the designated work areas in the system. Initially,
the desired material is loaded by the storage/retrieval
machine onto the outboard one of the double conveyors by
passing the cassette ~hrough the rack as before. From there,
the workman transfers the material to the inboard conveyor where
the work operation is performed. This permits the S/R machine
to load a seconcl cassette onto the outboard conveyor while the
machinist is working on the first load. After the work is
completed, the first load is transferred back through the rack
to the S/R machine and the second load is transferred from the
outboard conveyor to the inboar~ conveyor. In this manner, it
can be seen that the operator of the control console can keep
the machinist continuously supplied with material, rather than
requiring the workman to wait while the S/R machine returns the
first load before a second load can be retrieved.
In order to minimize the possibility of lost loads,
the storage/retrieval machine of the present invention is pro-
vided with an optical scanner that is adapted to read and decode
bar-coded information appearing on labels placed on the storage
cassettes to uniquely identify each cassette. The information
read from a cassette during a "STORE" operation is fed back to
the ground console where it is checked against the instructional
information provided to the storage/retrieval machine to insure
that the proper load is being stored. This checking system
greatly reduces the chances of misplacing a load as well as
providing an immediate indication of an error condition before
the error is compounded.
The entire system is adapted to be controlled and
monitored by an electronic control unit. The front panel of
the control unit or ground console contains a series of "STORE"
and "RETRIEVE" buttons actuable by the operator to control the
movement of the storage/retrieval machine. In particular, a
pair of "STORE" and "RETRIEVE" buttons is associated with each
conveyor in the system. Thus, if a particular cassette is to
be loaded onto conveyor No. 1, for example, the "RETRIEVE"
button associated with conveyor No. I would be actuated. The
"address" information of each conveyor -- i.e., its horizontal
and vertical location, the side of the aisle it is on, and its
laod capacity -- is preset for each particular system so that
whenever a "STORE" or "RETRIEVE" button is activated, the
information establishing the location of the selected conveyor
is automatically provided to the microprocessors which instruct
the movement of the storage~retrieval machine.
The "address" information of each cassette in the
system is contained on standard IBM computer cards. A separate
computer card is provided for each cassette and contains the
cassette's horizontal and vertical location in the racks, the
side of the aisle it is on, and the unique identi-fication
number of the cassette (which matches the bar-coded number on
the cassette). The card is inserted in a card reader on the
front panel of the ground console prior to activation of one of
the "STORE" or "RETRIEVE" buttons.
The ground console which controls the operation of the
storage/retrieval machine, always runs through a complete cycle
comprising the operations: (1) go someplace and pick up a
cassette; and (2) go someplace else and drop it off. Thus,
the storage /retrieval machine operates in two half cycles,
one half cycle under the control of the information from the
card reader and the other half cycle under the control of the
preestablished conveyor location information. Whether the
conveyor address or the card reader will control the first half
cycle
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f Operation depends upon whether a "STORE" or "RETRIE~E"
button has been actlvated. If a "RETRIEVE" button is selected,
the ground console will first instruct the S/R machine to
retrieve the cassette located at the address determinea by the
information from the card reader, and then to proceed to the
appropriate conveyor location and deposit the cassette.
Conversely, if a "~TORE" button is activated, the ground console
will instruct the S/R machine to first proceed to the appro-
priate conveyor location, pick up the cassette and store it
in the rack location determined hy the address information
from the card reader.
In the preferred embodiment, the ground console i5
also provided with a group of status lights located adjacent
to each pair of "STORE" and "RETRIEVE" control buttons to
provide a visual indication of the current status of each
conveyor. In this manner, a single operator can readily
I monitor all of the conveyors in the system. In addition, a
numerical display is also provided which is adapted to display
a predetermined error code whenever any of several identifiable
fault conditions occur.
Broadly speaking and in summary of the above the present
invention may be seen as providing in an automated storage
and retrieval system including a storage area comprising at
least first and second locations, a processing area having a
plurality of conveyors located adjacent storage locations in
the first row of storage racks, transfer means operatively
associated with each of the conveyors for transferring material
from the adjac~nt storage locations onto the conveyors and
from the conveyors into the adjacent storage locations, and
a storage and retrieval machine adapted to travel along the
aisle defined between the first and second rows of storage
racks and retrieve material from a first location in the
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storage racks and deposit the load .in a second location in
the sto.rage racks, the improvement comprising:
control means for controlling the operation of
the storage and retrieval machine including a control panel
having a plurality of status lights associated with each
conveyor in the processing area for indicating to the operator
the status of each of the conveyors, including a first light
that is activated when material is deposited by the storage/
retrieval machine into the storage location adjacent the
conveyor,
a second light that is activated when material is
deposited onto the conveyor, a third.light that is activated
when material is transferred by the transfer means from the
conveyor into the storage location adjacent the conveyor, and
a fourth light that is activated when both the conveyor and
the adjacent storage location are empty.
The present invention may also be seen as providing
in an automated storage and retrieval system including a
storage area comprising at least first and second parallel
rows of storage racks each haying a plurality of storage
locations, a processing area having a plurality of conveyors
located adjacent storage locations in the first row of storage
racks, transfer means operatively associated with each of the
conveyors for transferring material from the adjacent storage
locations onto the conveyors and from the conveyors into the
adjacent storage locations, and a storage and retrieval machine
adapted to travel along the aisle and retrieve material from
a first location in the storage racks and deposit the load in
a second location in the storage racks, the improvement com-
prising:
control means for controlling the operation of
the stora~e and retrieval machine in accordance with a first
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address which designates the location in the storage racks .
where the s'orage/retrieval machine is to proceed to retrieve
a desired load of matexial and a second address which designates
the location in the storage racks where the storage/retrieval
machine i5 to proceed to deposit the desired load of material,
including a control panel haYing ~irst and second contxol
switches associated with each single conveyor, the first con-
trol switch being operative to designate the location of the
storage location adjacent the respective conveyor as the first
address when activated and the second control switch being
operative to designate the location of the storage location
adjacent the respective conveyor as the second address when
activated, and input means for designating the second address
when the first control switch is activated and the first
address when the second control is activated.
~ ~ Further objects and advantages of the present inven-
tion will become apparent from a reading of the detailed des-
cription of the preferred embodiment which makes reference to
the following set of drawings in which:
Brief Description of the Drawings
Figure 1 is a plan view of a storage system embodying
the teachings of the present invention;
Figure 2 is an end view of the storage system shown
in Figure l;
Figure 3 is a sectional view of the storage racks
shown in Figure 1 taken along line 3-3;
Figure 4 is a plan view of the preferred layout of
the front panel of the ground console;
Figure 5 is a perspective view of the optical scanner
of the present invention;
Figure 6 appearing on the same sheet as Figure 3, is
a view of an exemplary bar code lable of the type appearing on
the cassettes;
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Figure 7 is a block diagram of the electronic control
circuit of the present invention; and
Figure 8 is a more detailed block diagram of the
ground console block of the control circuit shown in Figure 7.
Detailed Descri tion of the Preferred Embodiment
P
Looking to Figures 1 and 2, an exemplary layout of
a storage facility according to the present invention is shown.
The storage system illustrated and described herein is particul-
arly suited for the storage and handling of straight stock in a
steel warehouse. However, as will subsequently become apparent
to those skilled in the art, the teachings of the present
invention are readily adaptable to use in a wide variety of
storage applications requiring a greater or lesser degree of
storage and processing capabilities.
The storage facility illustrated in Figures 1 and 2
has a receiving area 12 and a shipping area 14. Incoming mater-
ial is transported from the receiving area 12, and outgoing
material is transp~rted to the shipping area 14, by an overhead
crane lS which is
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adapted to operate above the processing area as indicated in
Figure 1. Materia] is typically brought to the storage facility
by rail car 16 or by truck 18. lhe incoming material is then
unloaded from the railway car 16 or truck 18 by the overhead
crane 15 and deposited onto empty cassettes 32 located on the
loading conveyors 20. I`he loading conveyors 20 are positioned
adjacent the first row of racks 30 in aligned arrangement with
the rack openings 22 at the height of the conveyors 20.
Although only two loading conveyors 20 are shown, additional
conveyors may be provided if required.
Once the material has been loaded onto an empty
cassette 32 on one of the conveyors 20, the next step in storing
the material is to transfer the cassette 32 into the aligned
rack opening 22 adjacent the conveyor 20. Referring momentarily
to Figure 3, an end view of the racks 30 is shown. As can be
seen from the drawing, the racks 30 comprise a plurality of
storage bins 24 stacked atop one another between the floor 26
and the ceiling 28 of the building. In the preferred embodiment
illustrated herein, there are 46 bays per row and 22 shelves per
bay. The width and depth of each storage bin 24 is the same,
however, the heights of the bins 24 vary from 12 inches to 21
inches. Importantly, it will be noted that the bin opening 22
at the height of the loading conveyors 20 through which cassettes
are passed is at least as large as the largest bin size in the
racks so that all of the various sized cassettes can be
accommodated.
Returning to Figure 2, each of the input/output
conveyors 2~48 is equipped with a "grabberl' machanism 35 that
moves along the length of th~ conveyor 20~48 and is adapted to
either push a cassette 32 into the first ~ow of racks 30 or
pull a cassette 32 out of the first row of racks 30. It will
be noted at this point that the length of the cassettes 32,
wllich are all equal is greater than the depth of the storage
racks 30/50. In this manner when the cassettes 32 are
deposited into the racks 30/50 the ends of the cassettes will
protrude slightly from the racks 30/50 as shown in Figure 1.
This permits the grabber mechanism 35 on the conveyors 20/48
to engage the end o~ the cassette 32 that protrudes from the
racks 30.
Once a cassette 32 has been transferred from a loading
conveyor 20 into the aligned rack opening 22 adjacent the
conveyor 20 the cassette 32 is then drawn onto the storage/
retrieval machine 40 on the opposite side of the first row of
racks 30. The storage/retrieval machine 40 is equipped with
a mechanism commonly referred to as a "table" 41 that is adapted
to move in and out of the rack openings to store and retrieve
cassettes 32. The table 41 on the storage/retrieval machine
40 also includes a grabber mechanism similar to that on the
input/output conveyors 20/48 for engaging the ends of the cassetes
32 extending from the racks 30. Upon retrieving a loaded cassette
32 from the storage bin 22 adjacent a loading conveyor 20 the
storage/retrieval machine 40 is then adapted to automatically
store the loaded cassette 32 into a predetermined bin location
under the control of the ground conso].e 45. The storage/retrieval
machine 40 operates along a depression in the floor between the
two rows of racks 30 and 50 referred to as a "pit" 42. The
movement of the machine 40 as noted, is electronically con-
trolled by the control or ground console 45. The ground console
45 controls all three axes of movement of the storage/retrieval
machine 40; horizontal and vertical movement of the machine 40
between the two rows o~ racks 30 and 50 and the movement of
the table 41 into an~ out of the racks 30/50 to store and
retrieve the cassettes 32. .~s will subsequently be explained
in greater detail the ground console 45 also controls the
speed of the storage/retrieval machine 40 in accordance with
the distance the machine is from the desired rack location.
The storage/retrieval machine 40 provides position
feedback information to the ground console 45 via a pair of
absolute encoders 43 and 47. The encoders utilized in the
preferred embodiment are manufactured by Vernitron Corp.,
mfgr. No. OADC-30/5/BCDQ(200)L. One encoder 43 is utilized to
provide vertical position feedback information, and the other
47 is utilized to provide horizontal position feedback informa-
tion. As best illustrated in Figure 2, the vertical position
encoder 43 is mounted to the table 41 of the storage/retrieval
machine 40 and is adapted to engage a vertical guide rail
fastened to the machine 40. The horizontal position encoder
47 is mounted to the base of the storage/retrieval machine 40and
is adapted to engage a horizontal guide rail secured to the
side wall of the pit 42. In this manner, the ground console 45
can control the movement of the storage/retrieval machine 40
without having to count rack openings 24, thus permitting
accurate alignment of the table 41 with the rack openings
regardless of the size or locati.on of the rack openings 24.
In addition, the use of encoders eliminates the necessity of
having to return the storage/retrieval machine 40 to a base
location following a power shutdown or manual operation.
To retrieve stored material for shipment, the operator
of the ground console 45 merely instructs the storage/retrieval
machine 40 to retrieve the desired material from its storage
location in the racks 30/50 and insert the loaded cassette 32
into a bin location in rack 30 aligned with one of the shipping
conveycrs 48. From there, the grabber mechanism 35 on the
conveyor 48 draws the loaded cassette 32 onto the conveyor 48
where the material is banded and tagged for shipment. The
material is then removed from the cassette 32 and loaded onto
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a waiting truck or freight car by the overhead crane 15 and
the empty cassette 32 either returned to its rack loeation or
transferred to one Or the loadillg conveyors 20 for receipt of
additional incoming material.
Significantly, it will be noted that the provision of
a plurality of shipping conveyors 48 (herein four) provides
the present system with a substantial amount of flexibility in
handling the shipment of material. For example, one or more
of the shipping conveyors 48 can be used exclusively to main-
tain a supply in the shipping area 14 of the types of material
in the greatest demand. In this manner, the time of the storage/
retrieval machine 40 is not consumed by the repeated storage
and retrieval of the same material as would otherwise be
necessary to insure the availability at all times of an
unoccupied shipping conveyor 48. In addition, if an order is
received for only a few pieces of several different types of
material, the storage/retrieval machine 40 can deposit a load
of each type of material on one of the conveyors 48 so that
the desired pieces can be processed and loaded at the same time.
In addition, the present storage system also provides
efficient means for handling and transporting material to and
from a designated work area. In steel warehouses, for example,
orders are frequently received for custom material which must
be individually machined. Thus, special work areas easily
accessible by the storage/retrieval machine 40 must be provided
where such machining opera~ions can be performed. ~loreover,
since warehouse machines of this type are usually quite
expensive, it is important from a cost standpoint, that the
machi~es ~e kept as busy as po~sible. Accordingly, to satisfy
these requirements, the present system includes special double
conveyors 44/46 that are adapted to service a designated work
area, herein a pair of saw stations 47, in the processing area.
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As will be appreciated by those skilled in the art, the double
conveyors 44/46 provide a means of maintaining a continuous
supply of material at the workstations 47. In particular, the
material to be machined is initially retrieved by the storage/
retrieval machine 40 from its designated rack location and
inserted into the bin 54 aligned with either of the two out-
board conveyors 44. The loaded cassette is then drawn through
the racks 30 and onto the outboard conveyor 44. Once the cassette
is loaded onto the outboard conveyor 44, it is now under the
control of the workman at the workstation 47. When the workman
is ready to work on the material contained in the cassette on
the outboard conveyor 44, the cassette is transferred to the
inboard conveyor 46 from where the material can be individually
handled and machined. Once a cassette has been transferred from
the outboard conveyor 44 to the inboard conveyor 46, another
cassette can be loaded onto the outboard conveyor 44 and a
third cassette inserted into the now vacant bin 54 by the S/R
machine 40. Thus, when the workman has completed machining
the material from the first cassette, the cassette on the inboard
conveyor 46 can be transferred back into the racks 30 through
the aligned bin location 56 to the storage/retrieval machine
40, the loaded cassette on the outboard conveyor 44 trans-
ferred to the inboard conveyor 46, and the third cassette loaded
onto the outboard conveyor 44 from bin 54. In this manner, it
can be seen that the workman is not required to wait for the
storage/retrieval machine 40 to store the finished material
before the next load of material can be retrieved and trans-
ported back to the workstation 47. Accordingly, the efficiency
of the workman and the machines are improved.
Referring now to Figure 4, a pl~n view of the preferred
layout of the front panel of the control console 45 is shown.
As can be seen from the drawing, the control console 45 contains
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a pair of controi buttons 60 and 62, labeled "STORE" and
"RETRIEVE", for each input/output conveyor 20/48~ an~ a pair of
control buttons for each set of double conveyors 44/46. Ihe
control buttons appearing in phantom are shown to indicate that
additional sets of control buttons can be accommodated if
additional conveyors are utili~ed. The control buttons 60 and
62 associated with eacll conveyor are u~ilized to direct the
movement of cassettes to and from that conveyor. Specifically,
if a cassette is to be loaded OlltO a particular conveyor, the
"RETRIEVE" button associated with that conveyor is actuated.
Similarly, if a cassette is to be removed from a conveyor and
stored in the racks, the "STORE" button associated with that
particular conveyor is depressed.
Located above each pair of conveyor control buttons 60
and 62 is a set of status lights 64 which are adapted to provide
the console operator with complete in-formation as to the
current status of each conveyor in the system. In particular,
each of the individual input/output conveyors 20/48 has associated
therewith four status lights: (1) store, (2) empty, (3) ready,
and (4) full. The double conveyors 44/46 that service the
workstations 47, on the other hand, have six status lights:
(1) empty, (2) ready, and (3) full, associated with the out-
board conveyor 44, and (4) store, (5) empty, and (6) full,
associated with the inboard conveyor 46. When a cassette is
placed into the rack bin adjacent one of the conveyors by the
storage/retrieval machine 40, the "READY" light associated
with that conveyor will go on. The "FULI," light will turn on
when the cassette is transferred from the rack onto the con-
veyor. When the cassette is returned to the adjacent rack bin,
the "STORE't light will go on. And ~inally, when the storage/
retrieval machine 40 retrieves the cassette from the bin for
storage, the "EMPTY" 'ight will turn on. The status lights
associated with the dcublc conv~ctrs 44/~6 f~lnction in an
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identical manner with the fol]owing two exceptions. A "store"
status light is not required for the outboard conveyors 44
because a cassette is never removed from an outboard conveyor
44 by the storage/retrieval machine 40 for storage. Similarly,
a "ready" status light is not required for the inboard conveyors
46 because the storage/retrieval machine 40 never loads a
retrieved cassette onto an inboard conveyor 46.
As noted previously, the ground console 45 which con-
trols the movement of the storage/retrieval machine 40, always
runs through a complete cycle comprising the functions: "go
someplace and pick up a cassette; go someplace else and drop it
off." Thus, for each "STORE" or "RETRIEVE" instruction, the
storage/retrieval machine 40 must be provided with two address
locations: the address location of the place where the cassette
is to be picked up and the address location of the place where
it is to be dropped off. The address information required for
each operating cycle is provided by the card reader 66 and
the preset conveyor address information contained in the control
console 45. The card reader 66 is adapted to extract address
information from a plastic adaptation of a standard IB~I computer
card. Initially, a separate computer card is prepared for each
storage location in the racks 30/50. Each card contains the
following information: (1) the horizontal and vertical address
location of the storage bin, (2) the side of the aisle it is
located on, and (3) the identification or bar-code number of
the cassette located therein. The address information relating
to each conveyor, comprising: (1) horizontal and vertical
location, (2) the side of the aisle, and (3) load capacity, is
preset into the console 45 for each system layout and automati-
cally provided to the control circuitry whenever the "STORE" or
"RETRIEVE" button associated with a particular conveyor is
activated. Whether the preset conveyor address information or
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the address information from the card rea~er will control the
irst half cycle of operation of the storage/retrieval machi]le
40 depen~s upon whether the "STORE" or "RETRIF.V~" button is
activated. Specifically, if the "RETRIEVE" button 62 is
depressed, the ground console 45 will instruct the storage/
retrieval machine 40 to initia]ly proceed to the bin location
determined by the address information from the card reader 66,
retrieve the cassette stored therein, and then deposit the
cassette in the bin location in rack 30 adjacent the designated
conveyor. Conversely, if the "STORE" button 60 is activated,
the storage/retrieval machine 40 will retrieve the cassette
from the designated conveyor first before proceeding to the
bin location determined by the address information from the
card reader 66 to store the cassette therein.
Thus, to instruct the storage/retrieval machine 40 to
perform either a "store" or "retrieve" operation, the operator
first selects the computer card associated with the desirecl
cassette, inserts the card into the card reader 66, and then
depresses ei~her the "STORE" or "RETRIEVE" button associated
with the selected conveyor. For convenience, the preferred
control console 45 also includes a plurality of cardholders 68
located immediately above each pair of control buttons 60 and
62 for storing the address card of a cassette after it has been
deposited on one of the conveyors. In this manner the possi-
bility of accidently inserting the wrong address card into the
card reader 66 when the cassette is to be ret~rned to its
designated rack location is greatly reduced. Consequently,
the chances of misplacing or losing a load are reduced.
When instructing the movement of the storage retrieval
machine 40~ the oper~tor of the control console 45 must be
cognizant of the status of the selected conveyor to be involved
in the instruction. Specifically, before a "STORE" command
from a particular -onveyor can be properly executed, the
"STORE" status light associated with that conveyor must be
on. Similarly, in order to properly execute a "RETRIEVE"
command to a particular conveyor (except to one of the out-
board conveyors 44), the "EMPTY" status light associated with
that conveyor must be on. If the status of the selected
conveyor is wrong for a chosen command, the "COMMAND ERROR"
light 74 will go on when the "STORE" or "RETRIEVE" button for
that conveyor is pushed. The "COMMAND ERROR" light 74
indicates to the control operator that the cammand has not
been accepted by the control unit 45.
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.len a E~roL~er com~and is entered, the "I~l CYCI.F" light 78 will
turn on indicatiTIg that tile storage/retrieval machi.ne ~0 is
executing the command.
If during the performance of a command the control
unit 45 detects an error condition which prevents th~ cycle
from continuing,-the "C~CLE ERROR" light 76 will be activated.
Contemporaneously, the control unit 45 is adapted to generate
an error code identifying the type of error detected and dis-
play the error code on the console at 75 ~xamples of detect-
able error conditions include:
(1) store an oversized load
(2) store a load into a full rack location;
(3) the casette identification code does not agree
with the identification code on the computer card.However, as w.ill be readily apparent to those skilled in the
art, the present system can be easily adapted to detect numerous
other types of error conditions depending upon the requirements
of the particular storage facility,
As a means of significantly reducing the possibility of
lost loads, the present storage system incorporates a novel op-
tical scanner 70 located on the storage/retxieval machine 40
that is adapted to read the identification codes appearing on the
cassettes, When the system is .initially set up, a label containing
a unique bar code is placed in a predetermined location on each
cassette. In addition, the identification number represented by
the bar code is entered on the computer card associated with that
cassette, Thus, before the storage/retrieval machine 40 will
execute a STORE instruction and retrieve a cassette from a con-
veyor, the cassette identification code read by the scanner must
agree wi.th the identification number on the computer card. In
: particular, the microprocessor in the ground console, to be sub~
sequently described is programme to compare the identification
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,lumber read off the computer card by the card reader with the
i.dentification number read by the scanner. If the two num~ers
do not match the microprocessor is further programmed to instruct
the S/R machine 40 to return the cassette to the pass-through
rack opening adjacent the conveyor where the casse~te was picked
up. Contemporaneously, the "CYCLE ERROR" the light 76 is
activated and the identification code read by hhe scanner 70 is
displayed on the error code display 75,
The optical scanner utilized in the preferred embodi-
ment comprises a low power laser scanner 70, shown in Fi.gure 5,
that is mounted to the storage/retrieval machine 40 in a pre-
determined location so that the scanner 70 will be able to read
the bar codes on the cassettes when the storage/retrieval machine
40 is properly positioned adjacent a cassette, As the drawing
indicates, the position of the scanner is important since the
scanner 70 has a limited "reading area" 72, The scanner 70
utilized in the preferred embodiment is manufactured by Computer
Identics Corporation, Model 6000, and has an optical throw of
six inches, a field depth of six inches, and a scan height of 12
inches, Thus, the effective reading area 72 of the scanner 70,
as indicated by the shaded portion in the drawing, comprises a
6" x 12" rectangular area, The optical scanner 70 is adapted
to illuminate passing objects with a sweeping laser beam and
convert the reflected light signal into an electrical analog
signal, The analog signal is then provided to a decoding and
conversion circuit 73, which converts the analog signal to a
digital signal and examines the signal to determine if it meets
the proper criteria for a signal reflected from a valid code
. pattern. If it is determined that the signal is valid, the
digital signal is conditioned for transmission to the control
. console 45, The decoding and conversion circuit 73 ut;.lized in
the preferred embodiment is also manufactured by Computer Identics
Corporation as part of the optical scanning sys-tem
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and is referred to by the manufacturer as a "I)ecodatran".
With reference to Figure 6, the format of the bar
code utili~ed in the preferred embodiment is illustrated. As
can readily be seen from the drawing, the bar code employed
herein is similar to that frequently appearing on the packages
of many types of consumer products. In the present system,
a plastic label con+aining the identification code is placed
on the side of each cassette used in the storage facility.
The identification code, of course, defines a different
five digit number for each cassette. In this manner, when
the storage/retrieval machine 40 is instructed to store a
particular cassette, the bar code on the cassette can be
read by the optical scanner 70 and the identification number
checked with that appearing on the computer card for that
cassette, to insure that the proper cassette is being stored.
This procedure greatly reduces the possibility of lost loads
and consequently improves the operating efficiency of the
system. It is to be understood, that although the present
optical scanning system is adapted to read the bar code
located on the cassette only during a "STORE" instruction,
the present system can be readily adaptable to check the
cassette identification code during a "REIRIEVE" instruction
as well.
The output instructions entered by the operator of
the ground console 45 are provided to an electronic control
circuit which processes the instruction signals and provides
directive output signals which control the movement of the
storage/retrieval machine 40. Looking to Figure 7, a block
diagra~ of the control circuit 80 used in the preferred
embodiment is shown. At this point, it should be understood
that the implementation of the electronic control for the
present invention can be accomplished in numerous different
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ways, depending upon the approach of the particular designer.
Accordingly, only a description of the block diagram illustrating
the general approacll taken in the preferred embodiment will be
provided.
As can be readily seen from the drawing, the control
circuit 80 employs three separate microprocessors, one to
control each axis of movement. In particular, a first micro-
processor 8Z controls horizontal movement of the storage/
retrieval machine 40, a second microprocessor 84 controls
vertical movement of the machine 40, and a third microprocessor
86 controls movement of the table 41. The horizontal, vertical,
and table sections of the electronic control unit 80 operate
in essentially the same manner, therefore, the following
description of the horizontal section applies equally to
the vertical and table sections. The a.c. inputs block 90
represents a series of converter circuits that receive
signals from the storage/retrieval machine 40 and convert
these 120 volt a.c. signals to five volt d.c. signals. The
a.c. input signals from the storage/retrieval machine 40 are
also optically isolated from the d.c. output signals, as is
conventional in machine control circuits of this type. The
d.c. output signals are either a logic HI or a logic LO to
indicate either the presence or absence of the corresponding
a.c. input signals.
The d.c. output signals from the a.c. inputs block 90
~;
. are provided to an input interface block 92 which comprises
a series of tri-state gates that serve to gate the information
received from the storage/retrieval machine 40 for entry into
the microprocessor 82. The input interface block 92 also
gates the information received from the ground control 88
to be provided to the microprocessor 82. The microprocessor
82 "reads" the information interfaced by the input interface
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block 92 by providing an appropriate signal code on the
address buss line llO which enables the tri-state gates in
the input interface block 92, thereby placing the data from
the input interface 92 on the data buss line 112.
The microprocessor 82 instructs movement of the
storage/retrieval machine 40 via a return path through the
output interface block 98 and the a.c. outputs block 96. The
output interface block 98 comprises a series of latch circuits
(i.e. flip-flops) that are adapted to latch the information
present on the data buss line 112 when enabled by the appro-
priate signal code on the address buss line l10. The latched
d.c. logic information is then converted back to 120 volt a.c.
signals by the a.c. outputs block 96. The a.c. outputs block
96 has -four outputs -- forward (slow), reverse (slow), high
speed, and medium speed, -- which control the horizontal
speed and direction of the storage/retrieval machine 40.
The microprocessor 82 receives feedback information
relating to the actual position of the storage/retrieval
machine 40 from the horizontal encoder 47. The output
information from the encoder 47 is latched by the position
encoder interface block 100 which is enabled every few
milliseconds by a strobe signal received from the micro-
processor 82. The microprocessor 82 compares the actual
position of the storage/retrieval machine 40 as determined
by the encoder 47 with the desired location of the machine
40 as determined by the instructional information from the
ground control 88. If additional movement is required, the
microp~ocessor 82 instructs ~ovement of the storage/retrieval
machine 40 accordingly via the a.c. outputs
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block 96, The microprocessor 82 also determines the speed at
which the storage/retri~val machine 40 should move to the desired
location in accordance with the distance the machine 40 is away
from the desired location. If the storage/retrieval machine 40
is beyond a first distance, then the microprocessor 82 will
instruct the machine 40 to move at a hiyh rate of speed until
it is within a second predetermined distance from the desired
location, at which point the microprocessor 82 will instruct the
machine 40 to slow to a medium speed, Further, when the storage/
retrieval machine ~0 has converged to within a third prffletRrr.~ned
distance of the desired location, the microprocessor 82 will
instruct the machine 40 to slow to its slowest speed from which
it can come to a complete stop when the desired location i5
reached, These predetermined distances are set by the digit
switch module 102 which comprises a plurality of range switches
that can be set to any desired distance in accordance with the
mass of the storage/retrieval machine 40, In addition, the pre-
ferred embodiment of the control circuit 80 utilizes thumb wheel
microswitches which can be readily adjusted by the operator. In
this manner~ the distance settings can be easily altered by the
operator without having to change the softward of the system to
insure th~t the storage/retrieval machine 40 travels to the
desired location in a minimum amount of time.
The programma~le read-only memory block (PROM) 104
contains the softward for the microprocessor 82, and the master
control block 106 represents conventional buffering and inverter
; logic circuitry, interfaces to the microprocessor 82, as well as
on the control lines from the status flag displays and interrupt
controls, The display interface 108 is an optional circuit that
is required if a display terminal is desired.
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The vertical section of the control circuit 80
operates identically to the horizontal section. The table
section, however, includes a scanner interface block 115
in place of the position encoder interface 100, which receives
the serial output si~nals from the optical scanner 70 located
on the storage/retrieval machine 40 and converts the infor-
mation to parallel digital output signa]s which are provided
on the data buss line 116 to the microprocessor S6. As pre-
viously noted, the microprocessor 86 is programmed to compare
the information received from the optical scanner 70 with the
identification information received from the card reader on
the ground control 88. If the information from the two
sources does not agree, an error signal is generated.
Referring now to Figure 8, a more detailed block
diagram of the ground control circuit 88 is shown. Since the
circuitry is duplicated for each conveyor in the system, only
one setup will be described. The conveyor controls block
120 represents a group of relays which provide status signals
from the conveyor indicating the four status conditions
visually displayed on the control panel. The outputs from
the conveyor controls block 120 are provided to an a.c.
inputs block 122 which converts the incoming a.c. signals
to d.c. logic levels. The a.c. inputs block 122 also receives
and converts the output signals from the STORE and RETRIEVE
pushbuttons 124 associated with that conveyor. In this
manner, a direct interlock is provided to insure that the
particular instructions selected can be performed given the
- current status of the conveyor. Thus, as previously noted, a
bad command will not be accepted. The d.c. logic signals
from the ~ c~ inpu~s b~ock 122 along with the preset conveyor
address information from block 126,
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tre provicled to t-he c3round control ci.rcuit 128 In addition,
the ground control circuit 128 is also provided with the cassette
address informati.on from the outpu-t of the card reader 130,
17hen a STORE or RETRIEVE button for a particular
conveyor i6 actuated, all of the other conveyors connected to
the ground control circuit 128 are locked out, Thus, if ada-
itional control buttons are pushed before the storagejretrieval
machine 40 has completed its operating cycle, the instructions
will be iqnored. The ground control circuit 128 is adapted to
determine, in accordance with the instruction entered~ whether
the storage/retrieval machine 40 is to proceed to the conveyor
address or to the cassette address first, and to provide to the
electronic control circuit 80 the necessary address information
in thè appropriatè order
Specifically, as previously discussed, iE a STORE
button is actuated, the conveyor address indicates the location
where the S/R machine 40 must first proceed to retrieve the
desired cassette, and the cassette address indicates the rack
location where the S/R machine 40 must then proceed to deposit
the cassette. Similarly, if a RETRIEVE button is actuated,
the cassette address indicates the location where the S/R
machine 40 must first proceed to retrieve the desired cassette
and the conveyor address indicates the conveyor location where
the S/R machine is to deposit the cassette
~ hile the above description constitutes the preferred
embodiment of the invention, it will be appreciated that the
invention is
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susceptible to modification, variation and change without
departing from the proper scope or fair meaning of the
accompanying claims.
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