U.S. patent number 3,790,006 [Application Number 05/306,862] was granted by the patent office on 1974-02-05 for position control system for a warehouse apparatus.
This patent grant is currently assigned to Hartman Metal Fabricators, Inc.. Invention is credited to Elmer C. Hartman, III.
United States Patent |
3,790,006 |
Hartman, III |
February 5, 1974 |
POSITION CONTROL SYSTEM FOR A WAREHOUSE APPARATUS
Abstract
An automatic stacker or load carrier has a trolley section
movable down an aisle between a pair of storage racks, an elevator
movable vertically on the trolley, and a retractable fork mechanism
movable out of either side of the elevator to pick up a load from,
or deposit a load into, a selected bin in one of the racks. A
stationary console remote from the stacker is connected
electrically to the stacker by a plurality of brush contacts on the
stacker, which have sliding, electrical contact with a like
plurality of conductors, which extend from the console down the
aisle. By means of a computer connected to the console, an operator
can program the stacker to perform a plurality of successive pick
up and deposit operations to transfer loads between selected bins
and a loading station at one end of the aisle, or between selected
bins in the racks. At the end of each cycle, which comprises either
a pick up or deposit operation, the stacker remains stationary
until the computer enters the address of a new cycle.
Inventors: |
Hartman, III; Elmer C. (Geneva,
NY) |
Assignee: |
Hartman Metal Fabricators, Inc.
(Victor, NY)
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Family
ID: |
23187198 |
Appl.
No.: |
05/306,862 |
Filed: |
November 15, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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73159 |
Sep 17, 1970 |
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Current U.S.
Class: |
414/274; 318/603;
318/629 |
Current CPC
Class: |
B65G
1/0421 (20130101) |
Current International
Class: |
B65G
1/04 (20060101); B65g 001/06 () |
Field of
Search: |
;214/16.4A,16.4B
;318/603,629 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Forlenza; Gerald M.
Assistant Examiner: Johnson; R. B.
Attorney, Agent or Firm: B. Edward Shlesinger et al.
Parent Case Text
This is a continuation of applicant's pending patent application
Ser. No. 73,159, filed Sept. 17, 1970 now abandoned.
Claims
1. In an automatic warehousing system having a plurality of load
supports,
a load carrier movable selectively into different transfer
positions in which it registers with one of said supports,
a transfer device on said carrier extensible selectively out of
either side thereof to pick up a load from, or to deposit a load
onto, the registering support, control apparatus comprising
means remote from said carrier for developing control signals
therefor, including a pair of address signals for selecting the
transfer position of the carrier, and a third signal for selecting
the direction in which the transfer device is to extend during a
transfer operation,
a first pair of conductors for transmitting said address signals
from said remote means to said carrier,
drive means on said carrier connected to said conductors and
responsive to signals thereon to move said carrier to the transfer
position represented by said address signals,
a third conductor for transmitting said third signal to said
carrier,
said remote means including means for causing said third signal to
have selectively one of two different polarities depending upon
from which side of the carrier the transfer device is to be
extended during a transfer operation, and
means on said carrier connected to said third conductor and
operative during each transfer operation to cause said transfer
device to be extended from one side of said carrier, when said
third signal is positive, and to be extended from the opposite side
of said carrier, when
2. An automatic warehousing system as defined in claim 1,
including
a fourth conductor connecting said remote means to said
carrier,
means on said carrier for developing a cycle complete signal of
predetermined polarity each time said transfer device moves from
one to the other of its pick-up and deposit positions,
respectively,
means on said carrier operative, prior to movement of said transfer
device from its pick-up to its deposit position, to test for the
presence of a load on the registering load support,
means to develop a reject signal having a polarity opposite to that
of said cycle complete signal, when a load is detected on the
last-named support by said testing means, and
means for transmitting both said cycle complete and said reject
signals to
3. An automatic warehousing system as defined in claim 2,
including
means on said carrier for sensing the presence of a load on said
transfer device, and operative to generate a load aboard signal of
predetermined polarity, when a load is present on said device,
a fifth conductor for transmitting said load aboard signal to said
remote means,
said remote means including means for applying to said fifth
conductor a stacker travel signal having a polarity opposite to
that of said load aboard signal, and
means on said carrier for preventing transmission of said address
signals to said carrier except when said stacker travel signal is
applied to said
4. Automatic storage apparatus, comprising
a plurality of load supports,
a load carrier mounted to move selectively into different transfer
positions in which it registers with one of said supports,
means on said carrier for developing a pair of position signals
corresponding to the actual position of said carrier relative to
said supports,
means remote from said carrier including
signal storage means connected at one side to a computer
intermittently to receive and store sets of coded command signals
from the computer,
a plurality of relays connected to the opposite side of said
storage means selectively to be energized in accordance with
command signals from said storage means upon receipt of cycle
complete signals from said carrier,
means controlled by said relays to convert said command signals
into pairs of address signals, each pair of said address signals
corresponding to a different desired position
a pair of conductors for transmitting said address signals to said
carrier,
means on said carrier for comparing each pair of address signals
with said position signals,
drive means on said carrier operative, when the compared address
and position signals disagree, to move said carrier toward said
desired position until the compared address and position signals
agree,
means for stopping said drive means, when the compared address and
position signals agree, and said carrier is in said desired
position,
a load transfer device on said carrier movable automatically
between pick-up and deposit positions each time said carrier has
reached the transfer position determined by the last-transmitted
pair of address signals, to transfer a load between said carrier
and the registering support,
a third conductor connecting said carrier to said computer,
means on said carrier operative, each time said transfer device is
moved from one to the other of its pick-up and deposit positions,
to apply a cycle complete signal of predetermined polarity to said
third conductor for transmission thereby to said computer, thereby
again to enable said relays selectively to be energized to produce
the next pair of address signals corresponding to the next desired
position of said carrier, and
reject means on said carrier operative to apply to said third
conductor a reject signal having a polarity opposite to that of
said cycle complete signal, when the support onto which a load is
to be deposited by said
5. Automatic storage apparatus as defined in claim 4, including
load sensing means on said carrier operative to transmit said
reject signal on said third conductor to the computer, when said
transfer device moves from
6. Automatic storage apparatus as defined in claim 5, including
a fourth conductor connecting said carrier to said computer,
said computer being operative to apply an enabling signal of one
polarity to said fourth conductor during movement of said carrier
from one transfer position to another, and
means on said carrier for detecting the presence of a load on said
transfer device, and for applying to said fourth conductor a load
aboard signal having a polarity opposite to that of said enabling
signal, when a load is
7. Automatic storage apparatus as defined in claim 4, wherein said
means controlled by said relays comprises
a first plurality of switches responsive to certain of said relays
selectively to apply to one of said pair of conductors a first
voltage corresponding to one address signal of a pair thereof,
a second plurality of switches responsive to the remainder of said
relays selectively to apply to the other of said pair of conductors
a second voltage corresponding to the other of the last-named pair
of address signals,
each of said first and second pluralities of switches being divided
into two equal groups, the switches of one group of each plurality
being normally-closed normally to apply ground potential to said
pair of conductors, and the switches of the other group of each
plurality normally being open, and
means operable upon selective energization of said relays and
consequent selective changes in the positions of said switches to
apply different
8. Automatic storage apparatus comprising
a plurality of load supports,
a movable load carrier,
a load transfer device on said carrier movable selectively out of
either side thereof between pick-up and deposit positions,
respectively, to pick up a load from or to deposit a load onto a
load support,
signal-responsive drive means for moving said carrier selectively
to different positions to register with different load supports,
respectively,
control means remote from said carrier for developing address
signals to actuate said drive means to move said carrier
selectively into registry with different load supports,
means for actuating said load transfer device, when the carrier is
in registry with a load support, to pick up a load from or to
deposit a load onto the registering load support,
a computer connected to said control means and capable of storing a
plurality of different programs, so that said control means is
actuated to cause said drive means to move said carrier into
registry with different load supports on successive operations of
said control means,
means connecting said load transfer device to said computer to
cause actuation of said control means after each pick-up and after
each deposit operation of said load transfer device,
a storage rack containing certain of said supports,
means mounting said carrier for movement in an aisle adjacent said
rack, and
said control means including means for moving said carrier
successively from registry with one to another of said supports in
said rack in response to successive actuations of said control
means,
said control means further including means for applying, through
said connecting means to said transfer device, a control signal
having selectively different polarity, depending upon the side of
the carrier from which the transfer device is to move to execute a
pick-up or deposit operation, and
said actuating means including means for moving said device out of
one side of said carrier, when the last-named signal is of one
polarity, and for moving said device out of the opposite side of
the carrier when said
9. Automatic storage apparatus as defined in claim 8, wherein
said connecting means comprises a plurality of stationary,
electrical conductors extending down said aisle adjacent said
rack,
sliding electrical contacts on said carrier engaging said
conductors,
one of said conductors is used to transmit said last-named signal
through one of said contacts to said transfer device, and
other of said conductors are used to transmit between said control
means and said carrier additional pairs of control signals, the
pair of control signals on each of said certain other conductors
being of opposite
10. In an automatic warehousing system having a plurality of load
supports,
a load carrier movable selectively into different transfer
positions in which it registers with one of said supports,
a transfer device on said carrier reciprocable from a retracted
position on said carrier selectively out of either side thereof to
pick up a load from, or to deposit a load onto, the registering
support, control apparatus comprising
means remote from said carrier for developing control signals
therefor, including a first pair of signals for selecting the
transfer position of the carrier,
a first pair of conductors for transmitting said first pair of
signals from said remote means to said carrier,
drive means on said carrier connected to said first pair of
conductors and responsive to signals thereon to move said carrier
to the transfer position represented by said first pair of
signals,
a third conductor for transmitting from said remote means to said
carrier a third signal having selectively one of two different
polarities depending upon from which side of the carrier the
transfer device is to be extended during a transfer operation,
and
means on said carrier connected to said third conductor and
operative during each transfer operation to cause said transfer
device to be extended from one side of said carrier, when said
third signal is positive, and to be extended from the opposite side
of said carrier, when said third signal is negative, and
a fourth conductor for transmitting from said carrier to said
remote means a fourth signal each time said transfer device returns
to its retracted position on said carrier,
said remote means including means operative to change said first
pair of signals each time said fourth signal is applied to said
fourth conductor.
11. An automatic warehousing system as defined in claim 10,
including
means mounting said transfer device for movement upwardly and
downwardly on said carrier between pick-up and deposit modes during
a transfer operation, respectively, to pick up a load from, or
deposit a load onto, the registering support,
a fifth conductor for transmitting from said carrier to said remote
means a fifth signal whenever a load is present on said transfer
device, and
means operative, when said transfer device has returned to its
retracted position in its pick-up mode, automatically to move said
device down on said carrier to its deposit mode unless said fifth
signal is present on
12. An automatic warehousing system as defined in claim 11,
including
means for transmitting a sixth signal on said fifth conductor from
said remote means to said carrier to enable application of said
first pair of signals to said drive means,
means on said carrier for developing a reject signal, when said
transfer device attempts to transfer a load to an already occupied
load support, and
means for transmitting said reject signal from said carrier to said
remote means on said fourth conductor.
Description
This invention relates to automated stackers or load carriers of
the type employed in automatic warehouse systems, and more
particularly to a stacker which can be programmed automatically to
transfer loaded pallets between loading stations and selected bins
in one or more storage racks. In a more specific aspect, this
invention relates to an automatic stacker which can be programmed
by a computer disposed remote from the stacker.
Conventional stackers can be programmed to effect a single or dual
command - i.e., to effect automatic delivery of a load from a home
loading station to a selected bin in a nearby storage rack, and/or
to retrieve a load from a selected bin in the rack. Heretofore,
however, with many types of stackers it has been necessary to cycle
the stacker home after each command, whether single or dual, to
enable the operator to program the stacker for a new command. The
reason is that the address switches, which must be manually
actuated to program a command, have been mounted on the stacker
itself, and consequently it was essential that the stacker be
returned to the head of the aisle at the completion of a command so
as to be accessible to the operator for the programming of a new
command.
Some stackers, though, have been built with remote controls; which
in such cases may be located any desired distance from the stackers
which they control, and from the racks served by the stackers.
However, even where remote controls have been employed, it has been
necessary heretofore in the case of certain dual command stackers
to employ two separate sets of bin selector switches, one set for a
storage command and another set for a retrieval command.
A further disadvantage of prior such stackers is that they are
capable only of transferring loads between a loading station at one
end of the aisle in which the stacker travels and any one of the
bins in the associated racks; and they are not capable of
transferring loads between bins in the racks.
It is an object of this invention to provide an improved remote
controlled automatic stacker which does not have to return to any
particular home or operating station in order to be programmed.
Another object of this invention is to provide a novel stacker of
the type described which has only one set of selector switches
programmable by a computer remote from the stacker to effect
successive load pick up and deposit cycles for as long a period as
the computer imparts program information to the stacker.
A further object of this invention is to provide an automatic
stacker of the type described which is substantially more compact
and versatile than prior such stackers.
Other objects of the invention will be apparent hereinafter from
the specification and the recital of the appended claims,
particularly when read in conjunction with the accompanying
drawings.
In the drawings;
FIG. 1 is an end elevation and FIG. 2 is a schematic plan view of
part of a warehousing system and a typical stacker therefor made in
accordance with one embodiment of this invention;
FIGS. 3A, 3B, 3C, 3D, 3E and 3F are electrical wiring diagrams
illustrating one manner in which this stacker may be wired for
remote control operation, portions of the stacker also being
illustrated schematically; and
FIGS. 4 and 5 are truth charts for the horizontal and vertical
selector relays which control the corresponding motions of the
stacker.
Referring now to the drawings by numerals of reference, 20 (FIGS.
1, 2 and 3B) denotes generally a stacker comprising a trolley
portion 21, an elevator 22, which is mounted for vertical movement
on a mast 28 carried by the trolley, and a reciprocable,
load-bearing fork or shuttle mechanism 23, which is mounted on the
elevator for telescopic movement selectively out of opposite sides
thereof. Trolley 21 is mounted in a conventional manner for
movement by a motor HM (FIG. 3F) longitudinally in an aisle between
a pair of identical, spaced storage racks 24 and 25, and two pairs
of loading stations 26 and 27, which are located at opposite ends
of the aisle. The two racks 24 and 25 have their storage bins 29
arranged in confronting horizontal rows and vertical columns at
opposite sides of the aisle. The elevator 22 is movable vertically
on mast 28 by a motor VM (FIG. 3F); and the fork 23 is movable
laterally out of either side of the elevator by a motor LM (FIG.
3F). Each of the motors HM, LM and VM has a brake (not
illustrated), which normally is in its braking state, and which is
released in a known manner, when the associated motor is
energized.
Trolley 21 carries a horizontal sensing head HHD (FIG. 3B), which
travels just above a pair of series-connected wires HCW, that are
fixed to the floor beneath the stacker to extend longitudinally
down the aisle between the racks. These wires, which cross and
recross one another at spaced points along the aisle, from at
alternate intersections thereof a plurality of stable nulls, or
null points HO, H1, H2, etc. through HX, which are designed to
develop in head HHD a control signal that is used to stop trolley
21 precisely at any one of a plurality of different horizontal
positions in the aisle, in each of which positions the trolley will
be in registry with a pair of confronting columns of bins of the
racks. When the stacker 20 is properly positioned between one of
the pair of loading stations 26 and 27 (FIG. 2), the head HHD will
register with either the null point H0 or HX, respectively. The
remaining horizontal null points correspond in number to, and
register with, the columns of bins in each rack, and they are
positioned so that as the stacker registers with successive pairs
of confronting columns of bins during its movement in the aisle,
its head HHD will register successively with the corresponding null
points.
The elevator 22 carries a pair of vertically spaced heads UVHD and
LVHD (FIG. 3B), which cooperate with a further pair of
series-connected wires VCW mounted on the vertical mast 28 that
projects upwardly from the trolley 21 for movement therewith. As in
the case of the horizontal wires HCW, the vertical crossover wires
VCW cross and recross one another at vertically spaced intervals to
form at alternate crossings a plurality of null points, two of
which are illustrated at VN1 and VN2 in FIG. 3B. These null points
correspond to successive, vertically spaced rows of storage bins in
each rack, and are arranged so that point VN1 corresponds to the
lowest row of bins in each rack, point VN2 corresponds to the
second row of bins up from the bottom of each rack; and so on. In
cooperation with the heads UVHD and LVHD these wires serve to
position the elevator 22 in precise vertical alignment with any
selected row of bins in the racks in a manner described in more
detail below.
Mounted on the elevator for vertical movement therewith is a
vertical wiper VW (FIG. 3B), which has sliding electrical contact
with a vertical wiper track 183. Wiper track 183 is mounted on the
same mast 28 that supports the wires VCW, and comprises a plurality
of vertical spaced conductor bars, two of which are designated as
184-1 and 184-2, respectively. The number of conductor bars in
track 183 equals the number of rows of bays or bins arranged
vertically in each rack and, therefore, the number of null points
in the vertical wires VCW. The confronting ends of the vertically
spaced conductors 184-1, 184-2, etc. are connected to one another
by resistors 186, which are selected to develop a predetermined,
equal voltage drop (for example 1 volt) between adjacent conductors
in the track, so that the uppermost conductor in the track will be
at a higher voltage than the lowermost.
Fixed to a stationary support above the stacker 20 to extend down
the aisle between the racks is a horizontal wiper track 200 (FIG.
3B), comprising a plurality of horizontally spaced conductor bars
200-0, 200-1, etc. through 200-X. The trolley 21 carries a
horizontal wiper contact HW, which has sliding electrical contact
with the conductors of track 200. The bars in track 200 are two
greater in number than the columns of bays in each rack, and are
spaced along the aisle horizontally so that bar 200-0 registers
with the loading stations 26 at one end of the aisle, the bar 200-X
registers with the loading stations 27 at the opposite end, and the
remaining bars register with the columns of bays in the racks. As
in the case of the vertical track 183, confronting ends of adjacent
conductor bars 200 are connected by like resistors 199, which
develop predetermined equal voltage drops (for instance 1 volt)
between adjacent bars in the track 200.
The potentials on the wipers HW and VW correspond, respectively, to
the particular conductor bar of the tracks 200 and 183,
respectively, with which they are engaged at any particular moment.
The voltages on the horizontal and vertical wipers HW and VW thus
represent the actual position of the stacker 20 at any given
instant. For example, when the stacker 20 is properly positioned
between the loading stations 26, the horizontal wiper HW (FIG. 3B)
is at the ground potential of the bar 200-0, while its vertical
wiper VW is at the ground potential of the vertical conductor bar
184-1.
The stacker carries both a horizontal voltage comparator HVC and a
vertical voltage comparator VVC, each of which has a pair of input
terminals. The voltage of the horizontal wiper HW is applied by a
wire 30 to one of the input terminals of the horizontal comparator
HVC; and the potential of the vertical wiper VW is applied by a
wire 31 to one of the input terminals of the vertical comparator
VVC.
The other input terminals of the comparators HVC and VVC, as
represented by the wires 40 and 41, respectively, are adapted to be
placed selectively at different potentials corresponding to the
positions to which it is desired to dispatch the stacker trolley 21
and elevator 22. When the input potentials (40, 30) to the
horizontal comparator HVC are equal, the trolley 21 stops; but when
these inputs are unequal, the trolley moves in a direction to
equalize these inputs. Similarly the elevator 22 is moved
vertically whenever the inputs (41, 31) to the vertical voltage
comparator VVC are unequal, and its vertical movement is stopped,
when the inputs 41, 31 are equal.
The dispatch signals to the comparator leads 40 and 41 are provided
by a plurality of address selecting relays CR1 through CR11 (FIG.
3A), which are mounted in a stationary console (not illustrated)
remote from the stacker, and which are energizable selectively by
signals emanating from a conventional computer (not illustrated).
The address relays CR1, CR2, CR3 and CR4 control the vertical
position of the elevator 22 by operating a vertical voltage
selector denoted generally at VVS in FIG. 3B; and the relays CR5,
CR6, CR7, CR8, CR9, CR10 and CR11 control the horizontal position
of the trolley portion 21 of the stacker through operation of a
horizontal voltage selector denoted generally at HVS in FIG. 3B. In
FIG. 3B the components to the left of the broken line A are located
in the stationary console, while the apparatus and circuits carried
by the stacker 20 are illustrated at the right of this line.
The horizontal voltage selector network HVS comprises two identical
sets of series connected resistors R1 through R7 (FIG. 3B)
corresponding, for example, to 10, 20, 40, 80, 100, 250 and 500
ohms, respectively. The resistors R1 to R7 of one set (the left
hand set in FIG. 3B) are connected, respectively, in parallel with
normally-open relay switches CR11, CR10, CR9, CR8, CR7, CR6 and
CR5, respectively, between a line 201 and a direct current power
source 208 of, for example, 100 volts. The resistors R1 to R7 of
the other set (the right hand set in FIG.3B) are connected,
respectively, in parallel with normally-closed relay switches CR11,
CR10, CR9, CR8, CR7, CR6 and CR5, respectively, between the line
201 and ground. Consequently, when switches CR5 through CR11 are in
the positions illustrated in the drawing (FIG. 3B), line 201 will
be placed at ground potential, and 100 ma. flows in the circuit,
with the full 100 volt potential on terminal 208 being dropped
across the left hand set of resistors R1 to R7. When, however, the
positions of these switches are reversed, line 201 will be at the
potential of terminal 208, or at 100 volts. By selective
energization of the relays CR5 to CR11 as illustrated in part by
the chart in FIG. 4, the potential applied by the selector HVS to
line 201 can be made to be any-where from zero to 100 volts.
The vertical voltage selector VVS (FIG. 3B) comprises ten terminals
VO through V9 separated from one another by like, series connected
resistors, each of which may have a value, for example, of 20 ohms.
Terminal V0 is connected to ground potential, and terminal T9 to a
direct current power source 207 (e.g. 24 volts) which is operative
to maintain terminals VO through V9 at voltage potentials of zero
through 9 volts, respectively. These terminals are adapted to be
connected selectively to a line 202 by a bank of relay switches
CR1, CR2, CR3 and CR4, some of which are normally open, and some of
which are normally-closed. When these switches are in the positions
shown in FIG. 3B, the zero voltage or ground potential of terminal
VO is applied to line 202. By selective operation of the relays CR1
to CR4 in the manner indicated by the chart in FIG. 5, the
terminals VO to V9 may be connected selectively to line 202 thereby
to apply anywhere from zero to nine volts to line 202.
Line 201 extends down the aisle between the racks 25 and 24, and is
slidingly engaged by a wiper contact 201' carried by the stacker,
and connected through a normally-open relay switch CR50-3 and a
normally-closed switch CR79-1 to horizontal comparator input 40.
Line 202 also extends down the aisle between racks 25 and 24, and
is slidingly engaged by another wiper contact 202', which is
mounted on the stacker for movement therewith, and which is
connected through normally-open switch CR50-4 and normally-closed
switch CR79-2 with the vertical comparator input 41. It is
therefore possible to apply preselected horizontal and vertical
address signals to the comparators HVC and VVC regardless of where
the stacker is located in the aisle.
As shown in FIG. 3C, additional wiper contacts 203', 204' and 205'
are carried by the stacker 20 for transmitting signals between the
console and the stacker along lines 203, 204 and 205, respectively.
These signals are controlled, at least in part, by solid state
logic circuitry (FIGS. 3D and 3E), which is mounted on a stacker
control panel for movement with the stacker.
The address signals AS1 through AS11 (FIG. 3A) for controlling the
address relays CR1-CR11 originate at the computer with a twelfth
address signal AS12, which determines which rack (left or right) is
to be serviced by the command represented by the stacker
dispatching signals AS1-AS11. Each of the twelve address signals
AS1-AS12 is applied to one of the inputs of twelve dual input AND
gates G1 through G12, respectively, the outputs of which are
applied in parallel to the inputs 1 to 12 of a twelve bit register
302 (FIG. 3A). The outputs 1 to 12 of register 302 are applied
through conventional DC amplifiers 303 to the relays CR1-CR12,
respectively; relay CR12 being operable, as noted hereinafter, to
determine from which side of the elevator 22 the fork or shuttle 23
will advance, when the stacker reaches its programmed
destination.
The computer also develops at certain times a "clear" signal CLR
(FIG. 3A), which is applied to one of the inputs of an AND gate
G13; a "load" signal LS which is applied to the input of AND gate
G14; and a "read" RS signal, which is applied to the input of an
AND gate G15. The other input to each of gates G13, G14 and G15 is
a "code" signal CS, which is developed at the computer to supply
signals, for example, selectively to one of a plurality of stackers
similar to stacker 20, and which is decoded at the stationary
console by a conventional decoding device (not illustrated) before
being applied as an enabling signal to gates of the type denoted at
G13, G14 and G15. When gate G13 is enabled, it produces at its
output a signal 304, which resets register 302, and resets a flip
flop 306, which controls an "enabling" relay CR13. When G14 is
gated it produces at its output a signal 308, which is applied to
gates G1 through G12, and to flip flop 306 to set the latter and
energize CR13. When G15 is gated, its output signal 310 is applied
to one of the inputs of AND gates G25, G26, G27 and G28, which will
be described hereinafter.
Power for operating the console and stacker circuits, including the
stacker motor control circuits of FIG. 3F, is supplied from a
conventional three phase alternating current power source through a
manually operable power switch MPP (FIG. 3B) to power lines L1, L2
and L3. Line L1 supplies power to the console (FIG. 3C), while all
three of these lines are connected (for example by conventional
wiper contacts, not illustrated) to the input terminals T1, T2 and
T3 (FIG. 3B) of a control panel on the stacker 20.
To avoid unnecessary repetition, it will be assumed hereinafter
that the switch MPP has been closed to apply power to the
system.
With switch MPP closed, the hot terminals T1, T2 and T3 (FIG. 3B)
on the stacker energize the stacker power lines L1', L2' and L3',
respectively. Line L1' energizes a photo cell unit PC3, which is
mounted on the stacker elevator 22 to detect the presence or
absence of a load on the fork or shuttle 23. If a load is present
the load will prevent light from a lamp on the elevator from
falling on the photo cell PC3, and consequently will permit its
associated switch PC3-1 (FIG. 3D) to return to its normally-closed
position. If on the other hand there is no load on the elevator,
the photo cell PC3 will be actuated by the light from its
associated lamp, and switch PC3-1 will be held open.
On the negative half-cycle of the voltage applied to line L1' upon
the closing of switch MPP, a "cycle complete" relay CR15 (FIG. 3C)
in the stationary console is energized from line L1' through the
normally-closed relay switch CR53-1, the diode D1, the
normally-closed switch CR53-2, the wiper contact 204' on the
stacker, conductor 204, diode D2 and relay CR15 to ground. A diode
D3 and a bin reject relay CR16 are connected in parallel with the
diode D2 and relay CR15, but diode D3 is oriented oppositely with
respect to the diodes D1 and D2, so that it prevents current flow
in the bin reject relay CR16, when the cycle complete relay CR15 is
energized. The now energized relay CR15 closes its switch contacts
CR15-1 (FIG. 3C) and CR15-2 (FIG. 3A), thereby sending a "cycle
complete" signal to one of the inputs of the dual input AND gate
G25 (FIG. 3A), and energizing a time delay unit TD1 (FIG. 3C),
which momentarily delays the energization of a reset relay CR18.
This relay is used to indicate the absence of power in the stacker
logic. At this time the stacker-power-on switch SPON (FIG. 3B) has
not yet been closed, so that after a brief delay the relay CR18 is
energized by TD1 and closes its switch CR18-1 (FIG. 3A) to send a
"power off" or "reset" signal to one of the inputs of the AND gate
G28.
At this time, assuming that the signals from the computer are
intended for stacker 20, the decoder (not illustrated) on the
console will produce the code signal CS (FIG. 3A), which partially
enables gates G13, G14 and G15. At this time also the computer
applies a "read" signal RS to gate G15 to determine the present
mode of the stacker. Gate G15 is therefore enabled and produces an
output signal 310 which is applied to one of the inputs of each of
the AND gates G25, G26, G27 and G28, which when gated, send signals
to the computer. Since switches CR15-2 and CR18-1 are closed at
this time, gates G25 and G28 are enabled and send "cycle complete"
and "reset" signals, respectively, to the computer. It will be
assumed that there is no load on elevator 22 at this time, so that
switch CR17-1 (FIG. 3A) is open and G27 is not gated.
The computer responds to the "cycle complete" signal by sending a
"clear" signal CLR together with the code signal CS to the gate G13
so that the latter is enabled and produces an output signal in line
304, which resets the twelve bit "Address" register 302 and the
"enable" flip flop 306. Normally, when a pluraity of successive
commands are being fed to the stacker by the computer, the "cycle
complete" signal appears only momentarily, each time the fork
mechanism retracts back onto the elevator 22 after a pickup or
deposit operation, or just long enough to reset the register 302
and the flip flop 308. At this time, however, power has not yet
been applied to the stacker logic circuitry, (i.e., switch SPON
(FIG. 3B) has not yet been pushed closed) so that the energizing
voltage for relays CR15 and CR18 continues to be applied through
switches CR53-1 and CR53-2 (FIG. 3C). The prolonged energization of
relay CR15, and the consequent energization of relay CR18,
indicates to the computer that the stacker power must be "reset" or
turned on by pushing switch SPON. This reset condition, which may
be indicated at the computer by a print out or other visual
indicator means, will occur whenever relay CR18 is energized.
For purposes of explanation, it will be assumed that the empty
stacker is positioned between the load stations 26, and that it is
desired to pick up a loaded pallet from the left hand station 26
(FIG. 2), and to place this pallet in the right hand rack 24 in a
bin 29 which is the fourth bin up from ground level in the fourth
column of bins down the aisle from stations 26. To perform these
operations, the computer is programmed to instruct the stacker to
perform two successive cycles; the first cycle comprising picking
up the load from the left station 26, and the second comprising
depositing the load in the selected bin. A "cycle complete" signal
is generated at the end of each of these cycles.
The operator now closes the stacker Power On switch SPON to
energize the main control relay MC from the line L1' through the
normally-closed stacker Power On switch SPOF and switch SPON. This
closes a holding switch MC-2 to maintain the relay MC energized
upon release of the switch SPON, and closes switch MC-1 to supply
power to the stacker logic through leads 4L1, 4L2 and 4L3. These
leads then remain energized until relay MC is deenergized, for
example by the manual opening of switch MPP, or by a conventional
safety circuit (not ilustrated). Instantly the Power On relay CR53
(FIG. 3C) is energized from line L1' through the holding switch
MC-2, line 35 and relay CR53 to ground, thereby opening the
switches CR53-1 and CR53-2 and removing the signal from wiper
contact 204'. This deenergizes the "cycle complete" relay CR15,
thereby opening switches CR15-2 (FIG. 3A) and CR15-1 (FIG. 3C) and
deenergizing reset relay CR18-1 so that both the cycle complete and
reset signals are removed from the computer input.
When the "cycle complete" and "reset" signals are removed , the
computer initiates the first of the two above-noted cycles by
applying a "load" signal LS together with a code signal CS to the
inputs of gate G14 (FIG. 3A), at the same time that it applies the
programmed address signals to selected ones of the gates G1-G12.
Gate G14 is thus enabled, producing a signal in line 308, which
simultaneously "enables" those of gates G1 through G12 which are
receiving address signals from the computer, and sets flip flop 306
to energize the "stacker enabling" relay CR13. Relay CR13 then
closes its switches CR13-1 and CR13-2 (FIG. 3C).
At this time, since the stacker is already in position to pick up a
load from station 26, it need not be moved before picking up the
load; and consequently no signals are present on any of the address
signal lines AS1 through AS11, whereby relays CR1 through CR11
remain deenergized. However, at this time the computer does apply a
signal to line AS12 (FIG. 3A) to energize relay CR12 to program the
forks 23 for movement left. Relay CR12 closes switch CR12-1 (FIG.
3C) and opens CR12-2 to energize the "forks left" relay CR48 on the
positive half cycle of the voltage in line L1 through CR13-1,
CR12-1 diode D6, line 203, wiper 203', diode D7 and CR48 to ground.
With relay CR48 energized, its switch CR48-1 (FIG. 3D) will be
closed to energize converter 903. Since at this time there is no
load on the elevator 22, switch PC3-1 (FIG. 3D) will be open, and
converter 906 deenergized.
Also at this time the switches which are illustrated as controlling
motors LM, VM and HM (FIG. 3F) are open, so these motors remain in
their deenergized, braked mode. Moreover, the now-energized line
4L1 energizes a transformer TR2 (FIG. 3B), and direct current power
supplies PS-1 and PS-2 (FIG. 3F) and PS-9 (FIG. 3D). The output of
the transformer TR2 supplies power for the vertical crossover wires
VCW (FIG. 3B); the power supplies PS-1 and PS-2 provide,
respectively, positive and negative 24 volt power supplies for the
stacker motor circuits (FIG. 3F); and the power supply PS9 supplies
a negative 125 volts DC for the stacker logic illustrated in FIGS.
3D and E. The power supply PS-1 also has its output connected to
the vertical wiper track 183 as shown in FIG. 3B.
The now-energized power supply PS-9 applies an input signal through
a pair of normally-closed switches PC1' and PC2' (FIG. 3D) to a
converter 911 in the stacker solid state logic. This produces an
output signal MM in the logic to indicate that the bin testing
system is ready. Switches PC1' and PC2' are controlled by
photoelectric cell units PC1 and PC2 (FIG. 3C), which are adaptd to
be energized selectively through normally-open relay switches
CR76-1 and CR78-1 from line 4L1. These units, which are
conventional, are mounted on the left and right hand sides,
respectively, of elevator 22 to detect the presence or absence of a
load in a selected bin, or on one of the loading stations, to
prevent the stacker from attempting to deposit a load in a filled
bin or station. Whenever either unit PC1 or PC2 is energized from
line 4L1 to perform a testing operation, the corresponding switch
PC1' or PC2', respectively, is opened. The normally-open switches
PC1-1 and PC2-1, however, which are in parallel with one another,
and in series with the converter 908 (FIG. 3D), are closed only
when the light from the lamp associated therewith is reflected onto
the photoelectric cell of the particular unit during conduction of
a test.
At this time the power On relay switches CR53-3 (FIG. 3C) and
CR53-4 are closed to enable the transmission of signals between the
stacker and console through the wipers 204' and 205'. Also, as
previously noted, relay CR13 has been energized by signals from the
computer, so that its switches CR13-1 and CR13-2 (FIG. 3C) are
closed. Consequently, on the positive half cycle of the voltage in
line L1, power is applied through these switches, a diode D8, line
205, wiper 205', switch CR53-4, line 39, diode D9 and both relays
CR50 and CR51 to ground. Relay CR51 then closes its switches CR51-1
and CR51-2 (FIG. 3F) so that signals may be sent the horizontal and
vertical motor controllers HMC and VMC as noted hereinafter. Also,
since the stacker travel enabling relay CR50 is now energized, its
normally-closed switches CR50-1 and CR50-2 (FIG. 3B) are opened;
its switches CR50-3 and CR50-4 are closed to enable address
voltages to be applied from selectors HVS and VVS to the inputs 40
and 41 of the horizontal comparator HVC and vertical comparator VVC
through the normally-closed switches CR79-1 and CR79-2,
respectively; and switch CR50-5 (FIG. 3D) is closed to energize
converter 910.
At this time, however, none of the address relays CR1-CR11 are
energized, so that lines 201 and 202 apply ground potential to the
comparator inputs 40 and 41. Since the stacker is between stations
26 with its elevator in its lowermost position (FIG. 3B), the
inputs 30 and 31 of the comparators HVC and VVC are also at ground
potentials.
The comparators HVC and VVC (FIG. 3B) operate in known manner to
control relays CR46, CR47 and CR41, CR42, respectively, which are
connected to their outputs. When the inputs to either comparator
are equal, there is no signal at the output of the comparator, and
consequently neither of its relays CR46, CR47 or CR41 or CR42 is
energized. If the inputs to a comparator HVC or VVC are different,
an output signal is produced to energize one of its output relays.
For the horizontal comparator HVC, if the address signal or voltage
on input 40 is greater than (more positive with respect to) the
signal on input 30, the relay CR46 will be energized to energize
the horizontal or trolley motor HM (FIG. 3F) in a direction to
drive the stacker 20 away from stations 26 and toward stations 27.
Merely for purposes of description, this will be referred to as the
forward direction of travel of the stacker. Conversely, if the
voltage on line 30 is greater than on the input line 40, the relay
CR47 will be energized and the stacker will travel in a reverse
direction (toward stations 26).
When the address voltage on the vertical comparator input 41 (FIG.
3B) is greater than that on line 31 the relay CR41 is energized to
cause the elevator to be driven upwardly; and when the voltage on
line 31 exceeds the voltage on line 41, the relay CR42 is energized
to drive the elevator downwardly.
Referring now to FIG. 3F, CR39 and CR44 represent two relays, which
control what may be defined as the "coarse" and "fine" feed
operations of the vertical and horizontal motors VM and HM. When
the two relays CR39 and CR44 are deenergized, the horizontal and
vertical motors HM and VM are in "coarse" control and will operate
at high speeds to move the stacker and elevator, respectively,
rapidly toward a selected designation; and when these two relays
are energized, the motors HM and VM are switched from "coarse" to
"fine" control mode in which they operate slowly to bring the
stacker and elevator precisely to the desired destination. During
"coarse" control predetermined direct current voltages are applied
to the horizontal and vertical motor controllers HMC and VMC (FIG.
3F); but during "fine" control variable signals are applied to the
inputs of the controllers from the sensing heads HHD and UVHD, LVHD
(FIG. 38) on the stacker. These heads develop signals only when
moved relative to their associated wires HCW and VCW, and during
"coarse" control they have no effect on the controllers HMC and
VMC. When input signals, either "coarse" or "fine," are applied to
the controllers HMC and VMC, the reversible motors HM (FIG. 3F) and
VM are rotated in one direction or the other, depending upon the
polarity of the input signals. Moreover, whenever the horizontal
motor HM is energized, the controller HMC energizes a horizontal
tachometer relay CR45;and when the motor VM is energized,
controller VMC energizes a vertical tachometer relay CR40. Relays
CR45 and CR40 control normally-closed switches CR45-1 and CR40-1
(FIG. 3D) in a zero center control circuit.
At this time relays CR39 and CR44 (FIG. 3F) are energized from the
power supply PS-1 through the normally-closed switches CR41-1 and
CR42-1, and the normally-closed switches CR46-1 and CR47-1,
respectively, and relays CR40 and CR45 are deenergized.
Consequently, the switches CR39-1, CR40-1, CR45-1 and CR44-1 (FIG.
3D) are closed, so that voltage is applied from PS-9 to the input
of the stacker converter 909. Also switches CR39-2 and CR44-2 (FIG.
3F) are open to isolate controllers VMC and HMC from the DC power
supplies PS-1 and PS-2, and switches CR39-3 and CR44-3 are closed
to enable signals developed by the head HHD to be applied through
switches CR44-3 and CR51-2 to the input of controller HMC and to
enable signals from head UVHD to be applied through CR71-1, CR39-3
and CR51-1 to the input of controller VMC. Since the stacker 20 is
now motionless in the position illustrated in FIG. 3B, its
horizontal head HHD registers with the null HO of the horizontal
wires HCW, and its upper vertical head UVHD is in registry with the
lowermost null VNL of the vertical wires VCW. As a result, no
sensing signals are developed in these heads by the associated
wires, and consequently at this time there are no input signals to
the horizontal and vertical controllers HMC and VMC. The vertical
and horizontal motors VM and HM therefore remain deenergized.
At this time the fork mechanism 23 is in its retracted or centered
position on elevator 22, where it holds closed two limit switches
FC-1 and FC-2 (FIG. 3D), which therefore complete a signal input
circuit from the power supply PS-9 to the converter 907. At this
time, therefore, the converters 903, 907, 909 910 and 911 (FIGS. 3D
and 3E) are receiving input signals. Converter 903 produces the
signal in line AA, which indicates to stacker 20 that its fork
mechanism 23 is to be moved to the left, when actuated. Converter
911 produces the signal MM, which indicates that the bin sensor
device is ready. Converters 907 and 909 now produce the
forks-centered signal FF and the stacker-centered signal DD,
respectively (FIGS. 3D and E).
Signal FF is applied to the input of a memory element M1, which
controls the mode of the fork mechanism 23 by preparing it for
either a "retract" or an "extend" operation. Although signal FF
tends to place M1 in its "extend" mode, it is already in this mode
as a result of having received an initial setting signal on line
110 from a unit reset device U1, which is energized from the power
supply PS-9 when the stacker switch SPON (FIG. 3B) is depressed.
Each time it is pulsed, the reset U1 (FIG. 3E) also resets the step
memories S1 and S2, the memory M2, the sealed AND element A15 to
produce the output signals in lines 119 (FIG. 3D), GG, 129 and 150,
respectively. The timer elements of the logic illustrated in FIGS.
3D and E are also reset upon the appearance of the signal 110 to
produce signals in lines 124 and 122 at the output of the timers T2
and T4, respectively.
At this time unit S1 (FIG. 3D), which controls the energization of
the upper and lower heads UVHD and LVHD (FIGS. 3B and 3F) by the
solenoid CR71 (FIG. 3D), has its output signal along line 118
blocked, which therefore prevents the energization of the relay
CR71, so that its normally-closed switch CR71-1 (FIG. 3F) remains
closed to maintin the upper vertical head UVHD energized, while the
switch CR71-2 remains open to deenergize the lower vertical head
LVHD. With the upper head energized, the elevator 22 is maintained
in its lower position with respect to the two different positions
it assumes for picking up and depositing, respectively.
Signal FF also blocks the output of the NOT element N2 (FIG. 3D)
and gates the AND/NOT element A'1 to produce the output signal in
line 121. For the first two seconds after the stacker switch SPON
(FIG. 3B) is closed, the resulting signal FF combines with the
input signal 124 at the AND/NOT unit A'2 (FIG. 3E) to produce an
output signal in line 127 that momentarily energizes the "cycle
complete" relay CR73. Signal FF is also applied to the input of the
two-second time delay element T2, so that approximately two seconds
after T2 is actuated, the latter is gated to produce the output
signal in line 147, and to block the output signal from line 124.
This removes the signal from line 124 to the input to element A'2,
and causes this element to switch its mode, thus blocking any
output signal to line 127 and deenergizing relay CR73, and
producing instead at A'2 an output signal through line 154. This
pulsing of the "cycle complete" relay CR73 occurs each time that
the forks-centered signal FF is generated at the completion of a
cycle, when the forks retract back onto the center of the elevator.
This pulse causes the momentary closing of the switch CR73-1 (FIG.
3C) so that a "cycle complete" signal can be transmitted from line
4L1, upon the negative half cycle of its voltage, through switch
CR73-1, diode D4, the now-closed switch CR53-3, the brush contact
204' and its associated conductor 204, the diode D2 and the relay
CR15 to ground. This, as noted above, momentarily closes switch
CR15-2 (FIG. 3F) to send a cycle complete signal to the
computer.
The output signal in line 154 (FIG. 3E) from the element A'2 is
applied with the signal DD (FIGS. 3D and 3E) to the AND element A14
(FIG. 3D) to produce an output signal in line 107, which gates the
OR element 03 to produce an output signal in line 130. The "pick
up" signal GG is applied to the input of the OR element 05 to
produce an output signal in line 131, which appears with the signal
in line 130 at the input of the AND element A8. The energized
converter 910 is producing the stacker enabling signal PP in the
stacker logic, thereby completing the input signals (150, 154, PP)
to the AND element A13, thus gating this element and producing a
signal in line 152. Signal 152 completes the input signals (130,
131, 152) to element A8, which is thus gated to produce the input
signal 133 for the timer T5. Approximately 5 seconds later this
timer is gated producing an output signal in line 148, which is
applied to the inputs of the AND elements A11 and A12. Since at
this time the forks are not extended, there is no input signal EE
for the NOT element N1, so that this element has an output signal
EE', which completes the input signals AA, BB, and EE' to the AND
element A3, thus gating this element and producing an output signal
in line 134, which gates the OR element 01. This produces an output
signal in line 142, which is applied to the input of the element
A11. At this time the bin sensor ready signal MM is applied to the
inputs of the AND elements A11 and A12. This completes the input
signals (142, 148, MM) to element A11, which is therefore gated
producing the output signal 144, which energizes the forks left
relay CR74 in the stacker logic.
The stacker now begins to operate because relay CR74 closes switch
CR74-1 (FIG. 3C) to energize the forks left relay LR from the line
4L1 through switches CR74-1, to normally closed right relay switch
RR-2, and relay LR to ground. The relay LR closes the switch LR-1
(FIG. 3F) to energize the reversible motor LM in a direction to
drive the associated fork mechanism 23 out of the left hand side of
the elevator 22 and beneath the load on the left hand loading
station 26.
As the fork mechanism 23 moves out of the left side of the
elevator, it allows the fork center switches FC-1 and FC-2 (FIG.
3D) to open, thus removing the input to the converter 907 and
blocking the output signal FF, so that during the time that the
forks are not centered on the elevator 22, the NOT element N2 has
an output signal FF', which energizes the relay CR79, reversing its
associated switches CR79-1, CR79-2, CR79-3 and CR79-4 from the
positions illustrated in FIG. 3B and holding these switches in
their reversed positions. This shunts the two input signals to each
of the horizontal and vertical voltage comparators HVC and VVC to
prevent energization of any of the relays CR41, CR42, CR46 and CR47
during the lateral movement of the fork mechanism.
The signal FF' also is applied to the inputs of elements A4 and A6,
neither of which is gated at this time; and signal FF' also gates
the OR elements 06 and 03 to produce signals in lines 146 and 130,
respectively. The signal in line 130 already exists at this time
because of the presence of a signal in line 107, which is not
blocked upon the removal of signal FF from elements T2 and A'2. The
reason for this is that although signal 124 now reappears at the
input to A'2, the latter is not gated because signal FF is missing,
therefore signal 154 remains to keep element A14 gated.
When the fork mechanism 23 has extended completely under the load
it closes the forks-left limit switch FLL (FIG. 3C) to energize the
forks-extended relay CR52 from of said carrier relative to said
supports, through switch FLL and relay CR52 to ground. The relay
switch CR52-1 (FIG. 3D) is thus closed to apply an input signal
from the power supply PS-9 to the converter 905 in the stacker
logic. This produces the fork-extended signal EE, which blocks the
signal EE' to deenergize element 01 to A11, and the relays CR74 and
LR. This stops the fork mechanism 23 in its extended position.
Signal EE also appears simultaneously at the input to the timer T1
and the amplifier SA1 (FIG. 3D). There is a delay of four seconds
before the timer T1 is gated, and during this period the amplifier
SA1 applies an output signal to line 113, which gates the step
memory S1 to block its output signal to line 119, and to produce
instead an output signal in line 118, which energizes the head
control relay CR71 to open switch CR71-1 (FIG. 3F) and to close
switch CR71-2, so that the upper vertical head UVHD becomes
deenergized, and the lower vertical head LVHD is instead energized.
Since it is not precisely in registry with the vertical null V1,
the lower head now develops a signal which, causes the elevator 22
to move slightly upwardly in a known manner unitl the lower
vertical head LVHD registers with the null VH, at which time the
elevator stops. This slight upward movement, which takes slightly
less than four seconds, is sufficient to cause the fork mechanism
23 to engage and lift the loaded pallet slightly off of the loading
station 26.
Shortly after the load is lifted, the timer T1 times out, and is
gated to produce an output signal in line 112 (FIG. 3D), which
switches the mode of the memory M1 to block its output signal BB,
and to produce the "retract" signal BB', which is applied to the
inputs of the AND elements A4 and A6. This causes the AND element
A6 to be gated, therefore producing an output signal in line 137,
which gates the OR element 02 to produce an input signal in line
143 to element A12. This completes the input signals (143, 148, MM)
to the element A12, which therefore energizes the forks-right relay
CR75 (FIG. 3D), thus closing the switch CR75-1 (FIG. 3C) to
energize the fork right relay RR from line 4L1 through switch
CR75-1, switch LR-2 and relay RR. This closes switch RR-1 (FIG. 3F)
in the lateral motor circuit to energize motor LM from the lines
4L1, 4L2 and 4L3 in the reverse direction. The now-loaded fork
mechanism 23 then begins to retract toward the right onto the
elevator.
As shown in FIG. 3D, during travel of the forks either to the left
or to the right in response to the output signals in line 144 or
145, the OR element 010 is gated to produce an output signal in
line 156, which is applied to the input of a time delay element T8,
which has a delay of approximately ten seconds before it is gated
to produce an output signal in line 157. Under normal operation
this output signal is not generated. If, however onstruction such
as a misplaced load should prevent the fork mechanism 23 from
completing its movement either outwardly, or rearwardly back onto
the elevator, within the ten second period, the timer T8 will be
gated to produce a signal in line 157, which will gate an OR
element 08 to energize a bin-reject realy CR7 in a manner which
will be described in more detail below.
After the load is picked up from the loading station, and during
the retraction of the load back onto the elevator, and switch FLL
(FIG. 3C) reopens to remove signal EE (FIG. 3D); and the lamp for
the photoelectric cell PC3 (FIG. 3B) is blocked, therefore
deenergizing the photocell and permitting its switch PC3-1 (FIG.
3D) to close to complete the input signal to the converter 906 from
the power supply PS9. This produces the signal NN indicating the
presence of a load on the fork mechanism but at this time (during
retraction) the input signal FF to the element A'1 is missing, so
that the latter element is not gated. The signal NN does gate at
this time the OR element 06 to maintain the signal in line 146 at
the inputs to the step memory units S1 and S2; but this has no
effect on these units at this time.
When the fork mechanism finally returns in loaded condition to the
center of the elevator, it once again closes the fork center
switches FC-1 and FC-2 (FIG. 3D) to apply an input signal to the
converter 907, thereby producing an output signal FF, and blocking
the output signal FF' of the NOT element N2. This removes the input
signal FF'from the element A6, thereby deenergizing the forks-right
relay CR75 to stop the lateral motor LM. The removal of signal FF'
also deenergizes the relay CR79 so that the inputs to the
horizontal and vertical voltage comparators HVC and VVC are no
longer shunted. Also at this time the cycle-complete pulse or
signal in line 127 (FIG. 3E) is triggered by the application of the
fork-centered signal FF simultaneously to the unit T2 and the
element A'2.
As noted above, during the two second interval it takes before the
timer T2 is gated, the element A'2 is momentarily gated to block
its output signal 154, and to produce an output signal in line 127,
which momentarily energizes the cycle-complete relay CR73. Also,
since the load-present signal NN is present, when the loaded fork
mechanism returns to the center of the elevator, the AND/OR element
A'1 is also gated to remove the output signal from line 121, and to
develop instead an output signal in line 120. Signal 121 is removed
in time to prevent the gating of the sealed AND element A15. Also,
the removal of signal 121 from the input to the step memory S1 has
no effect on the latter, which is already in the mode that produces
a signal in line 118. The blocking of signal through line 121 to
the input of the step memory S2, on the other hand, switches the
mode of this element from "pickup" to "deposit", by blocking the
output signal GG, and producing instead a signal GG. The signal in
line 120 energizes the load present relay CR72; and the signal FF
switches the memory M1 to block its output signal BB' and to
produce instead the output signal BB.
When the relays CR72 and CR73 are thus energized, they send signals
from the stacker to the remote console to indicate that the stacker
is loaded and ready to travel to the selected bin into which the
load is to be deposited. The relay CR72 closes switch CR72-1 (FIG.
3C) to apply the voltage of line 4L1, on the negative half cycle
thereof, through the switch CR72-1, a diode D11, the line 39, the
now-closed switch CR53-4, the brush 205' and its associated
conductor 205, the diode D12, and through the load-present or
load-aboard relay CR17 in the console to ground, thus energizing
relay CR17.
Also on the negative half cycle thereof, the voltage in line 4L1 is
applied through the now-closed switch CR73-1 (FIG. 3C), the diode
D4, now-closed switch CR53-3, the brush 204' and its associated
conductor 204, and through the diode D2 and the cycle-complete
relay CR15 in the console to ground.
Relays CR15 and CR17 close their associated switches CR15-1, CR15-2
and CR17-1 (FIGS. 3A and 3C), to energize the timer unit TD1 (FIG.
3C) and to apply "cycle complete" and "load aboard" signals to
gates G25 and G27 (FIG. 3A). The computer then sends the clear
signal CLR (FIG. 3A), which resets or clears the register 302 and
the enable flip-flop 306. By this time the time-delay period for
element T2 (FIG. 3E) has expired, and a signal in line 147 appears
at its output, thereby blocking the signal in line 124 so that
element A'2 is no longer gated, thereby blocking a signal from line
127 so that the cycle-complete relay CR73 is deenergized. This
opens switch CR73-1 and deenergizes CR15 to remove the
cycle-complete signal to the computer before TD1 times out, thus
preventing energization of the reset relay CR18.
When the register 302 has been cleared, and the "cycle complete"
signal has expired, the computer sends the next address to the
register 302 (FIG. 3A) to instruct the stacker 20 to deposit its
load in the right hand rack 23, fourth bin up in the fourth column
of bins down the aisle from stations 26. This address includes the
load signal LS and code signal CS to enable gate G14, plus the
address signals AS1, AS2 (vertical) and AS9 (horizontal). Since the
forks are to be extended to deposit in the right hand rack, the
signal AS12 is not present. Since the enabling signal in line 308
is present, gates G1, G2 and G9 are enabled and cause relays CR1,
CR2 and CR9 to become energized, thereby reversing the positions of
their associated switches in the vertical and horizontal selectors
VVS and HVS (FIG. 3B), and as indicated by the charts in FIGS. 4
and 5, producing a potential of three volts on line 202, and four
volts on line 201.
The enabling signal in line 308 has again set flip flop 306 so that
relay CR13 is energized, and so that its switches CR13-1 and CR13-2
(FIG. 3C) are closed. Since relay CR12 is not energized at this
time, on its negative half cycle the voltage in line L1 will
energize the forks-right relay CR49 from the line L1 through the
now-closed switches CR13-1 (FIG. 3C), CR12-2, the diode D13, the
conductor 203 and its associated brush 203' on the stacker 20, the
diode D14 and the relay CR49 to ground. This closes the associated
switch CR49-1 (FIG. 3D) to energize the stacker converter 904 from
the power supply PS-9, thus producing the output signal CC in the
stacker logic. Similarly the stacker travel relay CR50 will be
energized through switch CR13-2, etc., so that signals may be
applied from the voltage selector HVS and VVS to the comparator
inputs 40 and 41.
Since the voltage which is applied through line 201 to the
comparator input line 40 (FIG. 3B) is approximately four volts
greater than, or positive with respect to, the ground potential,
which is at this time applied by the horizontal wiper HW to the
other input lead 30 of the comparator HVC, this positive voltage
differential causes the "forward" relay CR46 of this comparator to
be energized. Also, since the voltage applied by the conductor 202
and its associated wiper contact 202' to the input lead 41 of the
vertical voltage comparator VVC also is approximately three volts
greater than the ground potential which is presently applied to the
other input terminal 31 of this comparator by the vertical wiper
VW, the "up" relay CR41 of the vertical comparator VVC is
energized.
The now-energized relays CR46 and CR41 cause their associated
switches CR46-1, CR46-2, CR41-1 and CR41-2 to be reversed from the
positions illustrated in FIG. 3F, thereby deenergizing the relays
CR39 and CR44. These latter relays in turn permit their switches
CR39-1 and CR44-1 (FIG. 3D) to return to their normally-open
positions, thereby opening the zero center circuit, and removing
the input to the converter 909 in the stacker logic. Also at this
time switch CR41-3 (FIG. 3F) is closed, and CR41-4 is open, so that
a positive, coarse, twenty-four volt signal is applied from the
power supply PS-1 through the now-closed switches CR41-3, CR39-2
and CR51-1 to the input of the vertical controller VMC. This
positive voltage energizes the vertical motor "up" relay VMU. Also
at this time switch CR46-3 is closed and CR46-4 is open, so that a
positive, coarse, twenty-four volt signal is applied from power
supply PS-1 through switch CR46-3, CR44-2 and CR51-2 to the
horizontal controller HMC, which in turn energizes the horizontal
motor "forward" relay HMF. At this time, and whenever the stacker
is in "coarse" control (i.e., relays CR44 and CR39 deenergized),
the switches CR44-3 and CR39-3 are open so that the signals
developed by the heads HHD and UVHD or LVHD, cannot be applied to
the associated controller HMC or VMC. The relay switches VMU-1 and
HMF-1 now close to energize the vertical and horizontal motors VM
and HM in the up and forward directions, respectively. Accordingly,
the trolley and elevator sections of the stacker travel
simultaneously toward the selected bin (4X4). During this stacker
movement the tachometer relays CR40 and CR45 (FIG. 3F) are
energized so that their switches CR40-1 and CR45-1 (FIG. 3D) are
held open.
When the carriage or trolley 21 has moved far enough down the aisle
to register approximately with the fourth column of bins in each
rack, its horizontal wiper HW (FIG. 3B) moves into contact with the
fourth conductor away from the conductor 200-0 in the horizontal
wiper track 200, so that the wiper HW will apply through the line
30 a voltage that is equal to the four volts then being applied by
the address selector HVS through line 40 to the other input of the
comparator HVC. Consequently the forward relay CR46 once again
becomes deenergized. Similarly, when the elevator 22 has traveled
upwardly far enough to register approximately with the fourth row
of bins, its wiper VW engages the third conductor up from the
lowermost conductor 184-1 in the vertical wiper track 183, whereby
the input voltage supplied by the line 31 to the vertical voltage
comparator VVC will be identical with the voltage then being
applied by the line 41 to the other input terminal of this
comparator from the address selector VVS. At this time the "up"
relay CR41 will therefore become deenergized. Consequently the
relays CR39 and CR44 (FIG. 3F) once again become energized so that
the coarse, positive, 24 volt inputs to the horizontal and vertical
controllers HMC and VMC are removed by the opening of the switches
CR45-3, CR41-3, CR44-2 and CR39-2.
At this moment both the trolley and elevator sections of the
stacker are moving so that signals are developed in the heads HHD
(FIG. 3B) and LVHD by the associated wire systems HCW and VCW.
Moreover, since relays CR39 (FIG. 3F) and CR44 are energized, these
signals are fed through the now-closed switches CR39-3 and CR51-1
to the input of the vertical motor controller VMC, and through
switches CR44-3 and CR51-2 to the input of the horizontal motor
controller HMC so that the horizontal and vertical motors HM and VM
are now controlled by the head signals as in U. S. letters Pat. No.
3,349,303, issued Oct. 24, 1967 to Burch and Burnight. The heads
HHD and LVHD cause the carriage and elevator to stop in exact
registry with the selected bin (4X4) in rack 24. Moreover, since
the motors HM and VM have stopped, the associated tachometer relays
CR45 and CR40 have become deenergized.
The preceding operations of the motors HM qnd VM need not, of
course, always terminate simultaneously. I.e., either motor HM or
VM may halt in advance of the other, assuming the associated
trolley or elevator section reaches its destination in advance of
the other section.
At this time switches CR39-1, CR44-1 and CR45-1 (FIG. 3D) are
closed, so that power is applied to converter 909. This developes
the zero-center signal DD, and initiates a test to determine
whether or not the selected bin is empty. The signal DD completes
the input signals in lines 154, DD to element A14 which therefore
is gated to produce the signal in line 107, which gates element 03.
This produces a signal in line 130, which is applied to the inputs
of elements A8, and T4. Element A4 is not gated at this time, but
after approximately one second delay, T4 is gated to block the
signal from line 122 and generate a signal in line 123. The removal
of the signal from line 122 blocks the output signal in line 155
from element 09; and the signal in line 123 completes the input
signals (GG', 147, 123) needed to gate the AND element A7, which
produces the output signal in line 132 that is applied to the input
of the AND element A10. The memory M2 is still producing the signal
in line 129 (until its mode is switched by an input signal in line
117), so that the input signals (129, 132, CC) to A10 are
completed, and A10 is gated to produce the test signal in line
139.
The signal in line 139 gates the OR element 04 to apply an input
signal through line 140 to the time delay unit T3, and
simultaneously energizes the right-bin-test relay CR78. Relay CR78
immediately closes switch CR78-1 (FIG. 3C) to energize the reflex
photoelectric cell PC2 (FIG. 3C) at the right side of the elevator
from line 4L1 through switch CR78-1 and the unit PC2 to ground.
This opens switch PC2' (FIG. 3D) to deenergize converter 911 and to
remove signal MM from the stacker logic to prevent actuation of the
fork mechanism during the test period. There is approximately a two
second time delay before the signal in line 140 gates the unit T3
to product a reject signal in line 141. During this interval the
selected bin is tested by the unit PC2. If the selected bin is
already occupied by a loaded pallet, the light from the lamp in
unit PC2 is not reflected onto the associated photo cell, and
consequently the unit PC2 is not actuated at this time; but if the
selected bin is empty, the reflected light from the associated lamp
does actuate the cell PC2 to close its associated switch PC2-1 as
noted in more detail below.
Assuming that the selected bin (4X4) is full, and that the
photocell unit PC2 is not actuated, the time delay element T3 will
be gated after the expiration of the two second time interval,
producing the reject signal in line 141, which gates the OR element
08 to apply an actuating signal through line 149 to the bin-reject
relay CR77. Relay CR77 now closes its switch CR77-1 (FIG. 3C) to
apply a reject signal from the stacker to the console on the
positive half cycle of the voltage in the line 4L1 through the
switch CR77-1, a diode D15, switch CR53-3, the wiper contact 204'
and its associated conductor 204, and through the diode D3 and the
bin-reject relay CR16 in the console to ground. Relay CR16 closes
switch CR16-1 (FIG. 3A) to apply an input signal to gate G26, which
at this time also receives a signal through line 310 so that a bin
reject signal is sent to the computer.
When the computer receives the reject signal it indicates to the
operator in any desired manner (e.g. by operating a reject lamp or
printing out a reject notice) that the selected bin is loaded, and
that the computer must be reprogrammed to send the loaded stacker
to another bin. At this time the computer is still receiving the
"load aboard" signal from the output of gate G27 (FIG. 3A), memory
S1 (FIG. 3D) is still in the mode in which it energizes relay CR71
to maintain the lower vertical head LVHD energized, and memory S2
is still in its "deposit" mode producing signal GG'. Thus, assuming
that a new program is entered in the computer calling, for example,
for the load to be deposited in the left rather than the right bin,
the computer would send, together with the code signal CS, first
the clear signal CLR to reset the register 302 and the flip flop
306. As soon as the enable flip flop 306 is reset, it deenergizes
relays CR77 and CR78 so that the photo cell unit PC2 is
deenergized, and the cycle reject relay CR16 is consequently
deenergized. Then the computer sends the load signal LS together
with the new address signals, which would include signal AS12 to
effect energization of relay CR12 (FIG. 3A), and consequent
energization of the "left deposit" relay CR48 in a manner that will
be apparent from the above disclosure. Since the stacker is already
at its newly programmed destination, the bin test photo cell unit
PC1 is energized to check whether or not the left bin is loaded. If
the new address had necessitated movement of the stacker to a new
bin, this movement would, of course, occur before the bin testing
step.
Assuming that when the stacker reached the originally programmed
bin 4X4 the bin was empty, and that no reject signal was developed
in the logic, the photocell PC2 would have been energized by light
reflected back from the selected bin before the time delay element
T3 had had an opportunity to be gated. In this case the switch
PC2-1 (FIG. 3D) closes before timer T3 is gated. This applies an
input signal to the converter 908, which produces the bin-empty
signal HH in the stacker logic, thereby gating the OR element 07 to
produce a signal in line 117, which reverses the mode of the memory
M2 to block the signal from line 129, and to produce instead a
signal in line 128. The blocking of the signal from line 129
removes the input signal in line 140 from timer T3 before the
latter is gated, and also effects the deenergization of relay CR78
and the photo cell unit PC2.
The signal in line 128 now gates the OR element 05 to produce the
input signals (130, 131, 152) to element A8, which is gated to
produce the input signal through line 133 for the time delay
element T5, which has a one second delay to permit stabilization of
the logic signals before the forks are advanced. The time T5 thus
is gated to produce a signal in line 148, which is applied to the
input of the AND element A12. Since the photocell unit PC2 is
deenergized, switch PC2' has reclosed so that the bin-sensor-ready
signal MM (FIG. 3D) is also present at the input to A12. At this
time, the AND element A5 is gated by the input signals in lines CC,
BB and EE', thereby producing the output signal in line 136, which
gates the OR element 02. This produces a signal in line 143, which
completes the input signals (143, 148, MM) to the element A12,
which is gated to produce the signal in line 145, which energizes
the forks right relay CR75. The loaded forks are thus extended out
of the right side of the elevator into the empty bin.
When the forks are fully extended, they close the forks-right limit
switch FRL to energize the forks-extended relay CR52 (FIG. 3C) from
line 4L1. This closes switch CR52-1 (FIG. 3D) to apply a signal to
the converter 905, thus developing the signal EE in the stacker
logic. This blocks the NOT element N1 to remove signal EE',
therefore blocking element A5 and deenergizing relay CR75 to stop
the forks. The signal EE then actuates the signal amplifier SA1 to
switch the mode of memory S1 and deenergize relay CR71. The fork 23
then deposits the load in the selected bin. After the elevator has
dropped slightly to deposit the load in the bin, the reenergized
head UVHD "homes" out at the selected null point on wires VCW, and
the timer T1 is gated to effect return of the empty fork mechanism
to the center of the elevator. When the shuttle 23 is fully
retracted it momentarily develops the cycle-complete signal in line
127.
At this time, there is no load aboard the elevator so that the
photo cell unit PC3 is energized and switch PC3-1 (FIG. 3D) is held
open, therefore deenergizing converter 906 and removing signal NN
from the stacker logic. This deenergizes relay CR72 and opens
switch CR72-1 (FIG. 3C) so that the load aboard relay CR17 is
deenergized, thereby blocking gate G27 and removing the "load
aboard" signal from the computer. Since the stacker is motionless,
converter 909 is energized; the forks are centered so that
converter 907 is energized; the bin sensors are ready so that
converter 911 is energized, and the momentary application of the
cycle complete signal to the computer from gate G25 signals the
computer to send another address to the stacker.
In a manner that will be apparent from the above description, the
computer then transmits another address to the register 306 (FIG.
3A). Since the stacker is unloaded at this time, the new address
must, of course, amount to an instruction to pick up a load from
one of the bins or from one of the loading stations 26 or 27.
Assuming that the new address is to pick up a load from the bin
which is the second bin up in the second column of bins down the
aisle from the loading stations 26, the relays CR4 (vertical) (FIG.
3A) and CR10 (horizontal) will be energized to apply, for example,
two volts to the input lead 40 of the horizontal comparator HVC,
and one volt to the input line 41 of the vertical comparator
VVC.
Since at this time the horizontal and vertical wipers HW and VW
engage the four and three volt conductors, respectively, in the
horizontal and vertical wiper tracks 200 and 183, respectively, the
voltage inputs in the lines 30 and 31 are greater than, or positive
with respect to, the voltages applied to the respective comparators
by the leads 40 and 41. Consequently the reverse and the down
relays CR47 and CR42 (FIG. 3B), respectively, are energized by the
comparators to open switches CR42-1 (FIG. 3F) and CR47-2, thus
deenergizing the relays CR39 and CR44. This applies a coarse,
negative voltage from the power supply PS-2 through the now-closed
switches CR47-3, CR46-4, CR44-2 to the horizontal motor controller
HMC, and through the switches CR42-3, CR41-4, CR39-2 and CR51-1 to
the vertical controller VMC, respectively. These negative input
voltages cause the energization of the reverse and down relays HMR
and VMD, thereby closing switches HMR-1 and VMD-1 in the horizontal
and vertical motor circuits, respectively, so that the motors HM
and VM are energized to cause the trolley 21 and elevator 22 to
move simultaneously in the reverse and down directions,
respectively.
When the stacker elevator 22 is in proper registry with the
selected bin (2X2), the zero center circuit is once again energized
to provide a zero center signal DD in the stacker logic. This again
gates the AND element A14, but does not result in the gating of the
element A7, and the consequent energization of one of the bin
testing relays CR76 and CR78, because at this time the step memory
S2 is in its "pickup" mode, wherein it blocks the signal GG', which
is necessary for the gating of element A7. Output signal GG,
however, is present and gates the OR element 05 to complete the
input signals to the element A8, which therefore actuates the timer
unit T5 in a manner similar to that described above. Shortly
thereafter the signal 148 appears at element A12, which is already
receiving the bin-sensory-ready signal MM, because neither bin
testing photoelectric cell PC1 nor PC2 are energized at this time.
Also the signals CC, BB, and EE' are present at this time to gate
the element A5, which in turn gates the OR element 02 to complete
the input signals (143, 148, MM) to element A12, which therefore
energizes the forks-right relay CR75. The empty fork mechanism 23
then extends into the selected bin in the right hand rack to pick
up the load and to return to the center of the elevator in the
usual manner.
After the fork mechanism 23 has returned to the center of the
elevator, a test is made to determine whether or not it picked up a
load from the selected bin. This test is triggered by the pulsing
of the cycle-complete relay CR74, which occurs each time the fork
mechanism 23 is retracted onto the elevator.
Assuming that the fork mechanism did not pick up a load, the load
present signal NN is not present when the fork mechanism has
centered on the elevator. Consequently the element A'1 is not gated
to produce the load-present signal in line 120. Instead a signal
through line 121 is produced simultaneously with the production of
the cycle complete output signal 127 from the element A'2. Also at
this time, since the forks are elevated, the step memory S1 is
producing an output signal in line 118, which appears momentarily
with the signals in lines 121 and 127 at the input to the sealed
AND element A15. This gates A15 to produce a signal in line 151,
which gates the OR element 08 to energize the bin-reject relay
CR77.
The appearance of the forks centered signal FF at the input of the
NOT element N2 removes the output signal FF', and consequently
blocks the output signal in line 146 from the OR element 06, since
the other input signal NN (load-present signal) is not present at
the element 06 at this time. The blocking of the signal from line
146 switches the mode of the step memory S1 to block the output
signal in line 118 and to produce a signal in line 119, but not
before the signal in line 118 has gated the sealed AND element A15.
This deenergizes the head control relay CR71 so that the upper
vertical head UVHD once again becomes energized through the
now-closed switch CR71-1 (FIG. 3F). The elevator 22 is thus lowered
slightly until the upper vertical head UVHD registers with the
adjacent vertical null point VN2, corresponding to the bin (second
bin up in the second column of bins) from which the fork mechanism
23 had attempted to remove a load. The elevator is thus
automatically reset to a position in which the fork or shuttle will
pass beneath a load to pick it up, the next time that the shuttle
23 is advanced out of the elevator.
With the last-mentioned energization of the bin reject relay CR77,
a reject signal is transmitted in the usual manner from the stacker
20 through its wiper contact 204' (FIG. 3C) to' energize the reject
relay CR16 in the console. This closes CR16-1 (FIG. 3A) and enables
gate G26, which then sends a reject signal to the computer. Any
conventional means is then employed to alert the operator that the
stacker failed to pick up a load and that a new "pick up" program
is required.
Assuming that a load had in fact been retrieved from the second bin
up in the second column of bins in the right hand rack (bin 2X2),
the bin-empty reject signal would not have been produced by the
logic. In such case, as the loaded forks return to the center of
the elevator the forks-centered signal FF (FIG. 3D) is generated to
cause momentary energization of the cycle complete relay CR73, and
consequent gating of gate G25 (FIG. 3A) to send a cycle complete
signal to the computer. Also now, the load present signal NN (FIG.
3D) is present in the stacker logic so that the OR element 06 is
gated to maintain the input signal in line 146 for the step
memories S1 and S2. At this time, however, the load-present and
fork-centered signals NN and FF cause element A'1 to be gated to
block the signal from line 121, thereby maintaining the memory S1
in the mode to produce an output signal in line 118, which holds
the head control relay CR71 energized and the fork mechanism 23 in
its "upper" position. The removal of the signal from line 121 also
switches unit S2 into its deposit mode to block the output signal
GG, and to produce instead the output signal GG'. Element A'1 now
produces the signal 120, which energizes the load-present relay
CR72 so that gate G27 is enabled to advise the computer that there
is a load aboard the stacker.
After the computer receives the "cycle complete" and "load aboard"
signals, it transmits a "deposit" address to the register 302 (FIG.
3A) in a manner that will be apparent from the preceding
discussion. If the computer has not been programmed for another
address, the loaded stacker will remain motionless until a new
address is entered in register 302. If there is another address in
the computer ready for entry into the register 302, the new address
will enter the register in the usual manner and cause the loaded
stacker to travel to the new bin address. After arriving at the new
bin, the bin testing step will occur to determine whether or not
the bin is empty. If so the stacker will deposit the load in the
usual manner. On the other hand if the new bin is full, the bin
reject gate G26 will be enabled to pass the reject signal to the
computer, and to suspend operation of the stacker until a new
address is received.
After the load has been deposited in one of the bins, or on one of
the load stations 26 and 27, the load aboard gate G27 is
disenabled, and the cycle complete gate G25 is once again enabled
to inform the computer that the stacker is empty and ready for a
"pick up" operation.
From the foregoing it will be apparent that the computer-controlled
stacker disclosed herein is designed to develop a "cycle complete"
signal each time the forks 23 retract to their fully centered
positions on the elevator 22. Each time this signal occurs the
computer sends another address or command to the register 302, and
hence to the stacker logic. These commands merely instruct the
stacker to move to a particular bin or loading station, and
initially to move the forks either to the right or left. The
command does not include an instruction to "pick up" a load or to
"deposit" a load at the destination. This "pick up" or "deposit"
operation is determined by the mode of the stacker at the time it
reaches its addressed destination. If the stacker is already loaded
it attempts to deposit the load by first testing the new bin to see
if it is empty. If not, the "reject" signal is sent by gate G26 to
the computer, indicating that the loaded stacker must be
readdressed to an empty bin. Moreover, if the stacker attempts to
"pick up" a load from an empty bin or loading station 26 or 27, the
reject signal is produced and the elevator is automatially dropped
slightly to its "pick up" mode to be ready to pick up a load when a
new address is received from the computer.
With this form of control the stacker can transfer loads directly
from one bin to another, in the racks; or between the bins and
loading stations, or can transfer loads directly between the
loading stations 26 and 27 without first placing the load in one of
the storage bins. This type of control also permits the stacker to
remain in the aisle between the racks at the completion of a "pick
up" or "deposit" command rather than requiring the stacker to
return to a "start" position. Since the stacker can remain down the
aisle between the racks after depositing a load in one of the
racks, rather than having to return to the head of the aisle there
is a saving in time of operation achieved, for the stacker does not
have to return to a load station, and then travel away from that
station again to pick up or deposit a load; it is already down the
aisle, ready for a new pick-up or deposit operation. Thus, also, a
considerable amount of wear and tear on the stacker is avoided.
A still further advantage of this type of control is that much
information can be stored in the computer and retrieved when
desired. For example, if certain loads are to be removed from the
racks and delivered to a transport vehicle, for instance, at some
future time, the information may first be recorded in the computer,
and at a future time when the transport arrives, the information
can be transferred out of the computer to the register 302 to
effect the necessary retrieval operations.
Another advantage is that, merely by using the five sliding brush
contacts 201' through 205' on the stacker, together with their
associated conductors 201 through 205, it is possible to program
the stacker from any points remote therefrom -- even, for example,
from a control room separate from the room containing the stacker
20 and the associated racks. At no time, after having pushed the
stacker power-on button SPON, need the operator approach the
control circuitry on the stacker itself in order to manipulate any
of the switches manually, as was the case in most prior stackers.
Moreover, by sending more than one signal in opposite directions
through the wiper contacts on the stacker to the associated
conductors that lead to the remote console, both the cost and the
complexity of the stacker control circuitry is reduced. Also,
whenever power is removed from the logic circuitry on the stacker,
for example by pushing button SPOF (FIG. 3B), or by triggering a
conventional safety circuit (not illustrated) designed to
deenergize relay MC (FIG. 3B), the Power On relay CR53 is instantly
deenergized, thereby causing switches CR53-1 and CR53-2 to reclose.
This will, as noted above, result in energization of both the cycle
complete and reset relays CR15 and CR18 to signal the computer
operator that power is missing from the stacker logic.
Although the invention has been described in connection with the
use of ten rows and 100 columns of bins in each rack, it will be
apparent that a different number of bins may be employed if
desired. Moreover, although the loading stations 26 and 27 have
been selected to register with the lowermost row of bins in each
rack, it will be apparent that the height of the loading stations
may be altered merely by applying a different vertical address
voltage to line 41, when the stacker is between a pair of loading
stations.
* * * * *