U.S. patent application number 13/860802 was filed with the patent office on 2015-12-31 for autonomous transports for storage and retrieval systems.
The applicant listed for this patent is SYMBOTIC, LLC. Invention is credited to Foster D. Hinshaw, John Lert, Robert Sullivan, Stephen Toebes, Nathan Ulrich.
Application Number | 20150375938 13/860802 |
Document ID | / |
Family ID | 51686911 |
Filed Date | 2015-12-31 |
View All Diagrams
United States Patent
Application |
20150375938 |
Kind Code |
A9 |
Lert; John ; et al. |
December 31, 2015 |
AUTONOMOUS TRANSPORTS FOR STORAGE AND RETRIEVAL SYSTEMS
Abstract
An autonomous transport vehicle for transferring case units to
and from predefined storage areas in an automated case unit storage
system, the automated case unit storage system including an array
of multilevel storage racks with picking aisles passing
therebetween and at least one multilevel vertical conveyor having
movable shelves, the autonomous transport vehicle including a frame
configured to traverse the picking aisles and a transfer deck
connecting the picking aisles to the at least one multilevel
vertical conveyor for transferring case units between the
predefined storage areas and the at least one multilevel vertical
conveyor, and a controller connected to the frame, the controller
being configured to effect movement of the autonomous transport
vehicle through the picking aisles for accessing each storage area
within a respective level of the array of multilevel storage racks
and each shelf of the at least one multilevel vertical
conveyor.
Inventors: |
Lert; John; (Wakefield,
MA) ; Toebes; Stephen; (Sunderland, MA) ;
Sullivan; Robert; (Wilmington, MA) ; Hinshaw; Foster
D.; (Cambridge, MA) ; Ulrich; Nathan; (Lee,
NH) |
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Applicant: |
Name |
City |
State |
Country |
Type |
SYMBOTIC, LLC |
Wilmington |
MA |
US |
|
|
Prior
Publication: |
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Document Identifier |
Publication Date |
|
US 20140308098 A1 |
October 16, 2014 |
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Family ID: |
51686911 |
Appl. No.: |
13/860802 |
Filed: |
April 11, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12757312 |
Apr 9, 2010 |
8425173 |
|
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13860802 |
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61168349 |
Apr 10, 2009 |
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Current U.S.
Class: |
414/281 ;
414/267; 414/807; 701/23 |
Current CPC
Class: |
B65G 1/1373 20130101;
B65G 1/065 20130101; B65G 1/0492 20130101 |
International
Class: |
B65G 1/04 20060101
B65G001/04 |
Claims
1. An autonomous transport vehicle for transferring case units to
and from predefined storage areas in an automated case unit storage
system, the automated case unit storage system including an array
of multilevel storage racks with picking aisles passing
therebetween and at least one multilevel vertical conveyor having
movable shelves, the autonomous transport vehicle comprising: a
frame configured so that the autonomous transport vehicle
traverses, as a unit, the picking aisles and a transfer deck
connecting the picking aisles to the at least one multilevel
vertical conveyor for transferring case units between the
predefined storage areas and the at least one multilevel vertical
conveyor; and a controller connected to the frame, the controller
being configured to effect movement of the autonomous transport
vehicle through the picking aisles for accessing each storage area
within a respective level of the array of multilevel storage racks
and each shelf of the at least one multilevel vertical conveyor and
to effect dynamic allocation of case units of dissimilar sizes into
dynamically allocated storage areas in the array of multilevel
storage racks.
2. The autonomous transport vehicle of claim 1, further comprising
an effector integral to and dependent from the frame, the effector
defining a case unit seating surface contacting the case unit being
held by the effector, the effector being configured to hold the
case units and being configured to transfer the case units between
the autonomous transport vehicle and each storage area and between
the autonomous transport vehicle and the at least one multilevel
vertical conveyor.
3. The autonomous transport vehicle of claim 1, wherein the
autonomous transport vehicle is configured to transfer case units
between each storage area of a respective level of the array of
multilevel storage racks and the at least one multilevel vertical
conveyor with one pick.
4. An automated case unit storage system for handling case units
that are adapted for being palletized for shipping to or from a
storage facility, the automated case unit storage system
comprising: an array of multilevel storage racks having predefined
storage areas; a controller configured to effect dynamic allocation
of case units of dissimilar sizes into dynamically allocated
storage areas in the array of multilevel storage racks; and an
independent autonomous transport vehicle operatively connected to
the controller, the independent autonomous transport vehicle being
configured for traversing an aisle or deck within one level of the
multilevel storage racks and for transferring the case units to or
from the predefined storage areas, the autonomous transport vehicle
including an independent frame, a support shelf adapted for holding
at least one case unit thereon, the support shelf being movably
connected to the frame so that the support shelf is movable between
extended and retracted positions, a drive system mounted to the
frame, and guiding devices mounted to the frame; where the
independent autonomous transport vehicle is configured to effect
dynamic allocation of case units of dissimilar sizes into the
dynamically allocated storage areas.
5. The automated case unit storage system of claim 4, wherein the
dynamic allocation of case units comprises the autonomous transport
vehicle being configured to stop at a dynamically determined
position along picking aisles of the array of multilevel storage
racks for aligning at least a portion of the support shelf with a
case unit or empty space located in the array of multilevel storage
racks for effecting a transfer of at least one case unit between
the support shelf and a storage area corresponding to one of the
case unit or empty space.
6. The automated case unit storage system of claim 4, wherein the
array of multilevel storage racks comprise a floor having tracked
transport areas for guiding the autonomous transport vehicle
through tracked and un-tracked transport areas, the autonomous
transport vehicle being configured to transition between the
tracked transport areas and the un-tracked transport areas, the
guiding devices including at least one sensor configured to sense
at least one feature of the un-tracked transport areas for
contactlessly guiding the autonomous transport vehicle in the
un-tracked transport areas.
7. The automated case unit storage system of claim 4, wherein the
predefined storage areas include slatted storage shelves having
raised support surfaces separated by open channels, the guiding
devices including sensors for detecting the raised support surfaces
for locating the autonomous transport vehicle within the array of
multilevel storage racks and effecting dynamic allocation of the
case units in the predefined storage areas.
8. The automated case unit storage system of claim 7, wherein the
support shelf includes extendable fingers configured to pass into
the open channels for removing and placing case units on the
slatted storage shelves.
9. The automated case unit storage system of claim 7, wherein the
autonomous transport vehicle includes a lifting device for lifting
and lowering the support shelf for transferring case units to or
from the slatted storage shelves.
10. The automated case unit storage system of claim 4, wherein the
frame has a first end and a second end, the autonomous transport
vehicle further include a pair of individually operable drive
wheels disposed at the first end and driven by the drive system and
a pair of idler wheels disposed at the second end.
11. The automated case unit storage system of claim 10, wherein the
autonomous transport vehicle further includes at least one caster
disposed on the second end, the at least one caster being
configured for extension and retraction, where extension of the
caster raises the idler wheels off of a floor surface for allowing
the autonomous transport vehicle to pivot about the drive wheels on
the at least one caster.
12. The automated case unit storage system of claim 4, further
comprising: a substantially continuous lift configured to transport
case units to predetermined levels of the array of multilevel
storage racks, the substantially continuous lift comprising slatted
transport shelves adapted for holding case units thereon, the
autonomous transport vehicle being configured to directly or
indirectly place or remove case units from the transport shelves of
the substantially continuous lift.
13. A transport system for a storage and retrieval system having an
array of storage levels, each storage level having respective
storage areas, the transport system comprising: a vertical conveyor
having a frame and support shelves movably coupled to the frame,
each support shelf being configured to hold one or more uncontained
case units in predetermined areas of the support shelf; and
transfer vehicles disposed on respective ones of the storage
levels, the transfer vehicles being configured to transfer the
uncontained case units substantially directly between each support
shelf and the storage areas in substantially one transfer vehicle
picking operation.
14. The transport system of claim 13, wherein the support shelves
include first elongated fingers and the transfer vehicles include
second elongated fingers, the first and second elongated fingers
being configured to pass between one another for transferring
uncontained case units between each support shelf and the transfer
vehicles.
15. A method for handling case units that are adapted for being
palletized for shipping to or from a storage facility, the method
comprising: providing an array of multilevel storage racks having
predefined storage areas; and positioning an autonomous transport
vehicle within the array of multilevel storage racks for
dynamically allocating case units of dissimilar sizes into
dynamically allocated storage areas.
16. The method of claim 15, wherein dynamically allocating case
units comprises stopping the autonomous transport vehicle at a
dynamically determined position along picking aisles of the array
of multilevel storage racks and aligning at least a portion of a
support shelf of the autonomous transport vehicle with a case unit
or empty space located in the array of multilevel storage racks for
effecting a transfer of at least one case unit between the support
shelf and a storage area corresponding to one of the case unit or
empty space.
17. The method of claim 15, wherein positioning the autonomous
transport vehicle is effected by the autonomous transport vehicle
determining its position within the automated case unit storage
system through one or more of bot odometry, slat counting, index
counting and bar code reading.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/757,312 filed on Apr. 10, 2010 and claims
the benefit of U.S. Provisional Patent Application No. 61/168,349
filed on Apr. 10, 2009, the disclosure of which is incorporated
herein by reference in its entirety.
[0002] This application is related to U.S. patent application Ser.
No. 12/757,381, entitled "STORAGE AND RETRIEVAL SYSTEM," filed on
Apr. 9, 2010 with Attorney Docket Number 1127P013678-US (PAR); U.S.
patent application Ser. No. 12/757,337, entitled "CONTROL SYSTEM
FOR STORAGE AND RETRIEVAL SYSTEMS," filed on Apr. 9, 2010 with
Attorney Docket Number 1127P013888-US (PAR); U.S. patent
application Ser. No. 12/757,354, entitled "LIFT INTERFACE FOR
STORAGE AND RETRIEVAL SYSTEMS," filed on Apr. 9, 2010 with Attorney
Docket Number 1127P013868-US (PAR); and U.S. patent application
Ser. No. 12/757,220, entitled "STORAGE AND RETRIEVAL SYSTEM," filed
on Apr. 9, 2010 with Attorney Docket Number 1127P013867-US (PAR),
the disclosures of which are incorporated by reference herein in
their entireties.
BACKGROUND
[0003] 1. Field
[0004] The exemplary embodiments generally relate to material
handling systems and, more particularly, to transports for
automated storage and retrieval systems.
[0005] 2. Brief Description of Related Developments
[0006] Warehouses for storing case units may generally comprise a
series of storage racks that are accessible by transport devices
such as, for example, fork lifts, carts and elevators that are
movable within aisles between or along the storage racks or by
other lifting and transporting devices. These transport devices may
be automated or manually driven. Generally the items transported
to/from and stored on the storage racks are contained in carriers,
for example storage containers such as trays, totes or shipping
cases, or on pallets. Generally, incoming pallets to the warehouse
(such as from manufacturers) contain shipping containers (e.g.
cases) of the same type of goods. Outgoing pallets leaving the
warehouse, for example, to retailers have increasingly been made of
what may be referred to as mixed pallets. As may be realized, such
mixed pallets are made of shipping containers (e.g. totes or cases
such as cartons, etc.) containing different types of goods. For
example, one case on the mixed pallet may hold grocery products
(soup can, soda cans, etc.) and another case on the same pallet may
hold cosmetic or household cleaning or electronic products. Indeed
some cases may hold different types of products within a single
case. Conventional warehousing systems, including conventional
automated warehousing systems do not lend themselves to efficient
generation of mixed goods pallets. In addition, storing case units
in, for example carriers or on pallets generally does not allow for
the retrieval of individual case units within those carriers or
pallets without transporting the carriers or pallets to a
workstation for manual or automated removal of the individual
items.
[0007] It would be advantageous to have a storage and retrieval
system for efficiently storing and retrieving individual case units
without containing those case units in a carrier or on a
pallet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The foregoing aspects and other features of the disclosed
embodiments are explained in the following description, taken in
connection with the accompanying drawings, wherein:
[0009] FIG. 1 schematically illustrates an exemplary storage and
retrieval system in accordance with an exemplary embodiment;
[0010] FIGS. 2 and 3A-3C illustrate a transport robot in accordance
with an exemplary embodiment;
[0011] FIGS. 4A and 4B illustrate partial schematic views of the
transport robot of FIGS. 2, 3A and 3B in accordance with an
exemplary embodiment;
[0012] FIG. 4C illustrates a schematic view of a transport robot in
accordance with an exemplary embodiment;
[0013] FIGS. 5A-5C and 6A-6D illustrate a portion of a transfer arm
of the transport robot of FIGS. 12, 13A and 13B in accordance with
an exemplary embodiment;
[0014] FIG. 7 schematically illustrates a control system of the
transport robot of FIGS. 2, 3A and 3B in accordance with an
exemplary embodiment;
[0015] FIGS. 8, 9A and 9B schematically illustrate exemplary
operational paths of a transport robot in accordance with the
exemplary embodiments;
[0016] FIG. 10 schematically illustrates a portion of the control
system of FIG. 17 in accordance with an exemplary embodiment;
[0017] FIGS. 11A-11E, 12A, 12B, 13A and 13B schematically
illustrate exemplary operational paths of a transport robot in
accordance with the exemplary embodiments;
[0018] FIG. 14A illustrates a conventional organization of item
storage in a storage bay;
[0019] FIG. 14B illustrates an organization of items in a storage
bay in accordance with an exemplary embodiment; and
[0020] FIG. 14C illustrates a comparison of unused storage space
between the item storage of FIG. 14A and the item storage of FIG.
14B.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT(S)
[0021] FIG. 1 generally schematically illustrates a storage and
retrieval system 100 in accordance with an exemplary embodiment.
Although the embodiments disclosed will be described with reference
to the embodiments shown in the drawings, it should be understood
that the embodiments disclosed can be embodied in many alternate
forms. In addition, any suitable size, shape or type of elements or
materials could be used.
[0022] In accordance with one exemplary embodiment the storage and
retrieval system 100 may operate in a retail distribution center or
warehouse to, for example, fulfill orders received from retail
stores for case units (where case units as used herein means items
not stored in trays, on totes or on pallets, e.g. uncontained). It
is noted that the case units may include cases of items (e.g. case
of soup cans, boxes of cereal, etc.) or individual items that are
adapted to be taken off of or placed on a pallet. In accordance
with the exemplary embodiments, shipping cases or case units (e.g.
cartons, barrels, boxes, crates, jugs, or any other suitable device
for holding items) may have variable sizes and may be used to hold
items in shipping and may be configured so they are capable of
being palletized for shipping. It is noted that when, for example,
pallets of items arrive at the storage and retrieval system the
content of each pallet may be uniform (e.g. each pallet holds a
predetermined number of the same item--one pallet holds soup and
another pallet holds cereal) and as pallets leave the storage and
retrieval system the pallets may contain any suitable number and
combination of different items (e.g. each pallet may hold different
types of items--a pallet holds a combination of soup and cereal).
In alternate embodiments the storage and retrieval system described
herein may be applied to any environment in which items are stored
and retrieved.
[0023] The storage and retrieval system 100 may be configured for
installation in, for example, existing warehouse structures or
adapted to new warehouse structures. In one exemplary embodiment,
the storage and retrieval system 100 may include in-feed and
out-feed transfer stations 170, 160, multilevel vertical conveyors
150A, 150B, a storage structure 130, and a number of autonomous
vehicular transport robots 110 (referred to herein as "bots"). In
alternate embodiments the storage and retrieval system may also
include robot or bot transfer stations (as described in, for
example, U.S. patent application Ser. No. 12/757,220, entitled
"STORAGE AND RETRIEVAL SYSTEM," with Attorney Docket Number
1127P013867-US (PAR) previously incorporated by reference herein)
that may provide an indirect interface between the bots and the
multilevel vertical conveyor 150A, 150B. The in-feed transfer
stations 170 and out-feed transfer stations 160 may operate
together with their respective multilevel vertical conveyors 150A,
150B for transferring items to and from one or more levels of the
storage structure 130. The multilevel vertical conveyors may be
substantially similar to those described in U.S. patent application
Ser. No. 12/757,354, entitled "LIFT INTERFACE FOR STORAGE AND
RETRIEVAL SYSTEMS," with Attorney Docket Number 1127P013868-US
(PAR), previously incorporated by reference herein in its entirety.
It is noted that while the multilevel vertical conveyors are
described herein as being dedicated inbound conveyors 150A and
outbound conveyors 150B, in alternate embodiments each of the
conveyors 150A, 150B may be used for both inbound and outbound
transfer of case units/items from the storage and retrieval system.
The bots 110 may be configured to place items, such as the above
described retail merchandise, into picking stock in the one or more
levels of the storage structure 130 and then selectively retrieve
ordered items for shipping the ordered items to, for example, a
store or other suitable location. In one exemplary embodiment, the
bots 110 may interface directly with the multilevel vertical
conveyors 150A, 150B through, for example, access provided by
transfer areas 295 (FIGS. 8 and 11A-11E) while in other exemplary
embodiments, the bots 110 may interface indirectly with the
respective multilevel vertical conveyors 150A, 150B in any suitable
manner such as through bot transfer stations.
[0024] The storage structure 130 may be substantially similar to
the storage structure described in U.S. patent application Ser. No.
12/757,381, entitled "STORAGE AND RETRIEVAL SYSTEM," with Attorney
Docket Number 1127P013678-US (PAR) and U.S. patent application Ser.
No. 12/757,220, entitled "STORAGE AND RETRIEVAL SYSTEM," with
Attorney Docket Number 1127P013867-US (PAR), previously
incorporated herein by reference in their entirety. For example,
the storage structure 130 may include multiple levels of storage
rack modules, where each level includes picking aisles 130A (FIGS.
8-9D) that provide access to the storage racks, transfer decks 130B
(FIGS. 8-9D) that provide access to the picking aisles, and
charging stations (not shown) that are configured to replenish, for
example, a battery pack of the bots 110. The bots 110 and other
suitable features of the storage and retrieval system 100 may be
controlled by, for example, one or more central system control
computers (e.g. control server) 120 through, for example, any
suitable network 180. In one example, the central control computer
and network may be substantially similar to those described in U.S.
patent application Ser. No. 12/757,354, entitled "LIFT INTERFACE
FOR STORAGE AND RETRIEVAL SYSTEMS," having Attorney Docket Number
1127P013868-US (PAR), U.S. patent application Ser. No. 12/757,381,
entitled "STORAGE AND RETRIEVAL SYSTEM," having Attorney Docket
Number 1127P013678-US (PAR); U.S. patent application Ser. No.
12/757,220, entitled "STORAGE AND RETRIEVAL SYSTEM," with Attorney
Docket Number 1127P013867-US (PAR); and U.S. patent application
Ser. No. 12/757,337, entitled "CONTROL SYSTEM FOR STORAGE AND
RETRIEVAL SYSTEMS," with Attorney Docket Number 1127P013888-US
(PAR), previously incorporated by reference herein in their
entirety. The network 180 may be a wired network, a wireless
network or a combination of a wireless and wired network using any
suitable type and/or number of communication protocols. It is noted
that, in one exemplary embodiment, the system control server 120
may be configured to manage and coordinate the overall operation of
the storage and retrieval system 100 and interface with, for
example, a warehouse management system, which in turn manages the
warehouse facility as a whole.
[0025] As an exemplary operation of an order fulfillment process of
the storage and retrieval system 100, case units for replenishing
the picking stock are input at, for example, depalletizing
workstations so that case units bundled together on pallets (or
other suitable container-like transport supports) are separated and
individually carried on, for example, conveyors or other suitable
transfer mechanisms (e.g. manned or automated carts, etc.) to the
in-feed transfer stations 170. The in-feed transfer stations 170
assembles the case units into pickfaces (e.g. one or more case
units that may form a bot load) and loads the pickfaces onto
respective multilevel vertical conveyors 150A, which carry the
pickfaces to a predetermined level of the storage structure 130.
Bots 110 located on the predetermined level of the storage
structure 130 interface with the multilevel vertical conveyor 150A
at, for example, the transfer areas 295 for removing the pickfaces
from the multilevel vertical conveyor 150A. The bots 110 transfer
the pickfaces from the multilevel vertical conveyors 150A to a
predetermined storage module of the storage structure 130. When an
order for individual case units is made the bots 110 retrieve the
corresponding pickfaces from a designated storage module of the
storage structure 130 and transfer the ordered case units to
transfer areas 295 located on a level of the storage structure 130
from which the ordered case units were picked. The bots 110
interfaces with multilevel vertical conveyor 150B for transferring
the pickfaces to the multilevel vertical conveyor 150B. The
multilevel vertical conveyor 150B transports the ordered case
unit(s) of the pickface to the out-feed transfer stations 160 where
the individual case units are transported to palletizing
workstations by conveyors 230 where the individual case units are
placed on outbound pallets (or other suitable container-like
transport supports) for shipping to a customer.
[0026] As may be realized, the storage and retrieval system 100 may
include multiple in-feed and out-feed multilevel vertical conveyors
150A, 150B that are accessible by, for example, bots 110 on each
level of the storage and retrieval system 100 so that one or more
case unit(s), uncontained or without containment (e.g. case unit(s)
are not sealed in trays), can be transferred from a multilevel
vertical conveyor 150A, 150B to each storage space on a respective
level and from each storage space to any one of the multilevel
vertical conveyors 150A, 150B on a respective level. The bots 110
may be configured to transfer the uncontained case units between
the storage spaces and the multilevel vertical conveyors with one
pick (e.g. substantially directly between the storage spaces and
the multilevel vertical conveyors). By way of further example, the
designated bot 110 picks the uncontained case unit(s) from a shelf
730 of a multilevel vertical conveyor, transports the uncontained
case unit(s) to a predetermined storage area of the storage
structure 130 and places the uncontained case unit(s) in the
predetermined storage area (and vice versa). In one exemplary
embodiment, the storage and retrieval system 100 may include a bot
positioning system for positioning the bot adjacent the shelves 730
of the multilevel vertical conveyor 150A, 150B for picking/placing
a desired pickface from a predetermined one of the shelves 730
(e.g. the bot 110 is positioned so as to be aligned with the
pickface on the shelf or a position on the shelf designated to
receive the pickface). The bot positioning system may also be
configured to correlate the extension of the bot transfer arm 1235
with the movement (e.g. speed and location) of the shelves 730 so
that the transfer arm 1235 is extended and retracted to remove (or
place) pickfaces from predetermined shelves 730 of the multilevel
vertical conveyors 150A, 150B. It is noted that at least a portion
of the bot positioning system may reside within the control system
1220 (FIG. 7) of the bot 110.
[0027] Referring now to FIGS. 2-6D, the bots 110 that transfer
loads (e.g. pickfaces formed of at least one case unit) between,
for example, the multilevel vertical conveyors 150A, 150B and the
storage shelves of a respective level of storage structure 130 will
be described. It is noted that in one exemplary embodiment the bots
110 may transfer loads directly to and/or from the multilevel
vertical conveyors 150A, 150B as will be described below, while in
alternate embodiments the bots 110 may interface with the
multilevel vertical conveyors indirectly such as through the bot
transfer stations. In one example, the bots 110 may be configured
for substantially continuous operation. For exemplary purposes
only, the bots 110 may have a duty cycle of about ninety-five (95)
percent. In alternate embodiments the bots may have any suitable
duty cycle and operational periods.
[0028] As can be seen in FIG. 2, the bots 110 generally include a
frame 1200, a drive system 1210, a control system 1220, and a
payload area 1230. The drive system 1210 and control system 1220
may be mounted to the frame in any suitable manner. The frame may
form the payload area 1230 and be configured for movably mounting a
transfer arm or effector 1235 to the bot 110.
[0029] In one exemplary embodiment, the drive system 1210 may
include two drive wheels 1211, 1212 disposed at a drive end 1298 of
the bot 110 and two idler wheels 1213, 1214 disposed at a driven
end 1299 of the bot 110. The wheels 1211-1214 may be mounted to the
frame 1200 in any suitable manner and be constructed of any
suitable material, such as for example, low-rolling-resistance
polyurethane. In alternate embodiments the bot 110 may have any
suitable number of drive and idler wheels. In one exemplary
embodiment, the wheels 1211-1214 may be substantially fixed
relative to the a longitudinal axis 1470 (FIG. 4B) of the bot 110
(e.g. the rotational plane of the wheels is fixed in a
substantially parallel orientation relative to the longitudinal
axis 1470 of the bot) to allow the bot 110 to move in substantially
straight lines such as when, for example, the bot is travelling on
a transfer deck 130B (e.g. FIGS. 8-9B) or within a picking isle
130A (e.g. FIGS. 8-9B). In alternate embodiments, the rotational
plane of one or more of the drive wheels and idler wheels may be
pivotal (e.g. steerable) relative to the longitudinal axis 1470 of
the bot for providing steering capabilities to the bot 110 by
turning the rotational planes of one or more of the idler or drive
wheels relative to the longitudinal axis 1470. The wheels 1211-1214
may be substantially rigidly mounted to the frame 1200 such that
the axis of rotation of each wheel is substantially stationary
relative to the frame 1200. In alternate embodiments the wheels
1211-1214 may be movably mounted to the frame by, for example, any
suitable suspension device, such that the axis of rotation of the
wheels 1211-1214 is movable relative to the frame 1200. Movably
mounting the wheels 1211-1214 to the frame 1200 may allow the bot
110 to substantially level itself on uneven surfaces while keeping
the wheels 1211-1214 in contact with the surface.
[0030] Each of the drive wheels 1211, 1212 may be individually
driven by a respective motor 1211M, 1212M. The drive motors 1211M,
1212M may be any suitable motors such as, for exemplary purposes
only, direct current electric motors. The motors 1211M, 1212M may
be powered by any suitable power source such as by, for example, a
capacitor 1400 (FIG. 4B) mounted to the frame 1200. In alternate
embodiments the power source may be any suitable power source such
as, for example, a battery or fuel cell. In still other alternate
embodiments the motors may be alternating current electric motors
or internal combustion motors. In yet another alternate embodiment,
the motors may be a single motor with dual independently operable
drive trains/transmissions for independently driving each drive
wheel. The drive motors 1211M, 1212M may be configured for
bi-directional operation and may be individually operable under,
for example, control of the control system 1220 for effecting
steering of the bot 110 as will be described below. The motors
1211M, 1212M may be configured for driving the bot 110 at any
suitable speed with any suitable acceleration when the bot is in
either a forward orientation (e.g. drive end 1298 trailing the
direction of travel) or a reverse orientation (e.g. drive end 1298
leading the direction of travel). In this exemplary embodiment, the
motors 1211M, 1212M are configured for direct driving of their
respective drive wheel 1211, 1212. In alternate embodiments, the
motors 1211M, 1212M may be indirectly coupled to their respective
wheels 1211, 1212 through any suitable transmission such as, for
example, a drive shaft, belts and pulleys and/or a gearbox. The
drive system 1210 of the bot 110 may include an electrical braking
system such as for example, a regenerative braking system (e.g. to
charge, for example, a capacitor 1400 (FIG. 4B) powering the bot
110 under braking). In alternate embodiments, the bot 110 may
include any suitable mechanical braking system. The drive motors
may be configured to provide any suitable acceleration/deceleration
rates and any suitable bot travel speeds. For exemplary purposes
only the motors 1211M, 1212M may be configured to provide the bot
(while the bot is loaded at full capacity) a rate of
acceleration/deceleration of about 3.048 m/sec.sup.2, a transfer
deck 130B cornering speed of about 1.524 m/sec and a transfer deck
straightaway speed of about 9.144 m/sec or about 10 m/sec.
[0031] As noted above drive wheels 1211, 1212 and idler wheels
1213, 1214 are substantially fixed relative to the frame 1200 for
guiding the bot 110 along substantially straight paths while the
bot is travelling on, for example, the transfer decks 130B (e.g.
FIGS. 8-9B). Corrections in the straight line paths may be made
through differential rotation of the drive wheels 1211, 1212 as
described herein. In alternate embodiments, guide rollers 1250,
1251 may be mounted to the frame to aid in guiding the bot 110 on
the transfer deck 130B such as through contact with a wall 1801,
2100 (FIG. 8) of the transfer deck 130B. However, in this exemplary
embodiment the fixed drive and idler wheels 1211-1214 may not
provide agile steering of the bot 110 such as when, for example,
the bot 110 is transitioning between the picking aisles 130A,
transfer decks 130B or transfer areas 295 (FIGS. 8 and 11A-11E). In
one exemplary embodiment, the bot 110 may be provided with one or
more retractable casters 1260, 1261 for allowing the bot 110 to
make, for example, substantially right angle turns when
transitioning between the picking aisles 130A, transfer decks 130B
and bot transfer stations 140A, 140B. It is noted that while two
casters 1260, 1261 are shown and described, in alternate
embodiments the bot 110 may have more or less than two retractable
casters. The retractable casters 1260, 1261 may be mounted to the
frame 1200 in any suitable manner such that when the casters 1260,
1261 are in a retracted position both the idler wheels 1213, 1214
and drive wheels 1211, 1212 are in contact with a flooring surface
such as surface 1300S of the rails 1300 or a transfer deck 130B of
the storage structure 130, whereas when the casters 1260, 1261 are
lowered the idler wheels 1213, 1214 are lifted off the flooring
surface. As the casters 1260, 1261 are extended or lowered the
idler wheels 1213, 1214 are lifted off of the flooring surface so
that the driven end 1299 of the bot 110 can be pivoted about a
point P (FIG. 14B) of the bot through, for example, differential
rotation of the drive wheels 1211, 1212. For example, the motors
1211M, 1212M may be individually and differentially operated for
causing the bot 110 to pivot about point P which is located, for
example, midway between the wheels 1211, 1212 while the driven end
1299 of the bot swings about point P accordingly via the casters
1260, 1261.
[0032] In other exemplary embodiments, the idler wheels 1213, 1214
may be replaced by non-retractable casters 1260', 1261' (FIG. 4C)
where the straight line motion of the bot 110 is controlled by
differing rotational speeds of each of the drive wheels 1211, 1212
as described herein. The non-retractable casters 1260', 1261' may
be releasably lockable casters such that the casters 1260', 1261'
may be selectively locked in predetermined rotational orientations
to, for example, assist in guiding the bot 110 along a travel path.
For example, during straight line motion of the bot 110 on the
transfer deck 130B and/or within the picking aisles 130A the
non-retractable casters 1260', 1261' may be locked in an
orientation such that the wheels of the casters 1260', 1261' are
substantially in-line with a respective one of the drive wheels
1213, 1214 (e.g. the rotational plane of the wheels of the casters
is fixed in a substantially parallel orientation relative to the
longitudinal axis 1470 of the bot). The rotational plane of the
wheels of non-retractable casters 1260', 1261' may be locked and
released relative to the longitudinal axis 1470 of the bot 110 in
any suitable manner. For example, a controller 1701 (FIG. 7) of the
bot 110 may be configured to effect the locking and releasing of
the casters 1260', 1261' by for example controlling any suitable
actuator and/or locking mechanism. In alternate embodiments any
other suitable controller disposed on or remotely from the bot 110
may be configured to effect the locking and releasing of the
casters 1260', 1261'.
[0033] The bot 110 may also be provided with guide wheels
1250-1253. As can be best seen in FIGS. 3B and 3C, while the bot
110 is travelling in, for example, the picking aisles 130A and/or
transfer areas 295 (FIGS. 8 and 11A-11E) the movement of the bot
110 may be guided by a tracked or rail guidance system. It is noted
that the transfer areas 295 may allow the bots 110 to access
transport shelves 730 of the multilevel vertical conveyors 150A,
150B. The rail guidance system may include rails 1300 disposed on
either side of the bot 110. The rails 1300 and guide wheels
1250-1253 may allow for high-speed travel of the bot 110 without
complex steering and navigation control subsystems. The rails 1300
may be configured with a recessed portion 1300R shaped to receive
the guide wheels 1250-1253 of the bot 110. In alternate embodiments
the rails may have any suitable configuration such as, for example,
without recessed portion 1300R. The rails 1300 may be integrally
formed with or otherwise fixed to, for example, one or more of the
horizontal and vertical supports 398, 399 of the storage rack
structure 130. As can be seen in FIG. 3C the picking aisles may be
substantially floor-less such that bot wheel supports 1300S of the
guide rails 1300 extend away from the storage areas a predetermined
distance to allow a sufficient surface area for the wheels
1211-1214 (or in the case of lockable casters, wheels 1260', 1261')
of the bot 110 to ride along the rails 1300. In alternate
embodiments the picking aisles may have any suitable floor that
extends between adjacent storage areas on either side of the
picking aisle. In one exemplary embodiment, the rails 1300 may
include a friction member 1300F for providing traction to the drive
wheels 1211, 1212 of the bot 110. The friction member 1300F may be
any suitable member such as for example, a coating, an adhesive
backed strip or any other suitable member that substantially
creates a friction surface for interacting with the wheels of the
bot 110.
[0034] While four guide wheels 1250-1253 are shown and described it
should be understood that in alternate embodiments the bot 110 may
have any suitable number of guide wheels. The guide wheels
1250-1253 may be mounted to, for example, the frame 1200 of the bot
in any suitable manner. In one exemplary embodiment, the guide
wheels 1250-1253 may be mounted to the frame 1200, through for
example, spring and damper devices so as to provide relative
movement between the guide wheels 1250-1253 and the frame 1200. The
relative movement between the guide wheels 1250-1253 and the frame
may be a dampening movement configured to, for example, cushion the
bot 110 and its payload against any change in direction or
irregularities (e.g. misaligned joints between track segments,
etc.) in the track 1300. In alternate embodiments, the guide wheels
1250-1253 may be rigidly mounted to the frame 1200. The fitment
between the guide wheels 1250-1253 and the recessed portion 1300R
of the track 1300 may be configured to provide stability (e.g.
anti-tipping) to the bot during, for example, cornering and/or
extension of the transfer arm 1235 (e.g. to counteract any tipping
moments created by a cantilevered load on the transfer arm). In
alternate embodiments the bot may be stabilized in any suitable
manner during cornering and/or extension of the transfer arm 1235.
For example, the bot 110 may include a suitable counterweight
system for counteracting any moment that is created on the bot
through the extension of the transfer arm 1235.
[0035] The transfer arm 1235 may be movably mounted to the frame
1200 within, for example, the payload area 1230. It is noted that
the payload area 1230 and transfer arm 1235 may be suitably sized
for transporting cases in the storage and retrieval system 100. For
example, the width W of the payload area 1230 and transfer arm 1235
may be substantially the same as or larger than a depth D (FIG. 6B)
of the storage shelves 600. In another example, the length L of the
payload area 1230 and transfer arm 1235 may be substantially the
same as or larger than the largest item length transferred through
the system 100 with the item length being oriented along the
longitudinal axis 1470 (FIG. 4B) of the bot 110.
[0036] Referring also to FIGS. 4A and 4B, in this exemplary
embodiment the transfer arm 1235 may include an array of fingers
1235A, one or more pusher bars 1235B and a fence 1235F. In
alternate embodiments the transfer arm may have any suitable
configuration and/or components. The transfer arm 1235 may be
configured to extend and retract from the payload area 1230 for
transferring loads to and from the bot 110. In one exemplary
embodiment, the transfer arm 1235 may be configured to operate or
extend in a unilateral manner relative to the longitudinal axis
1470 of the bot (e.g. extend from one side of the bot in direction
1471) for increasing, for example, reliability of the bot while
decreasing the bots complexity and cost. It is noted that where the
transfer arm 1235 is operable only to one side of the bot 110, the
bot may be configured to orient itself for entering the picking
aisles 130A and/or transfer areas 295 with either the drive end
1298 or the driven end 1299 facing the direction of travel so that
the operable side of the bot is facing the desired location for
depositing or picking a load. In alternate embodiments the bot 110
may be configured such that the transfer arm 1235 is operable or
extendable in a bilateral manner relative to the longitudinal axis
1470 of the bot (e.g. extendable from both sides of the bot in
directions 1471 and 1472).
[0037] In one exemplary embodiment, the fingers 1235A of the
transfer arm 1235 may be configured such that the fingers 1235A are
extendable and retractable individually or in one or more groups.
For example, each finger may include a locking mechanism 1410 that
selectively engages each finger 1235A to, for example, the frame
1200 of the bot 110 or a movable member of the transfer arm 1235
such as the pusher bar 1235B. The pusher bar 1235B (and any fingers
coupled to the pusher bar), for example, may be driven by any
suitable drive such as extension motor 1495. The extension motor
1495 may be connected to, for example, the pusher bar, through any
suitable transmission such as, for exemplary purposes only, a belt
and pulley system 1495B (FIG. 4A).
[0038] In one exemplary embodiment, the locking mechanism for
coupling the fingers 1235A to, for example, the pusher bar 1235B
may be, for example, a cam shaft driven by motor 1490 that is
configured to cause engagement/disengagement of each finger with
either the pusher bar or frame. In alternate embodiments, the
locking mechanism may include individual devices, such as solenoid
latches associated with corresponding ones of the fingers 1235A. It
is noted that the pusher bar may include a drive for moving the
pusher bar in the direction of arrows 1471, 1472 for effecting, for
example, a change in orientation (e.g. alignment) of a load being
carried by the bot 110, gripping a load being carried by the bot
110 or for any other suitable purpose. In one exemplary embodiment,
when one or more locking mechanisms 1410 are engaged with, for
example, the pusher bar 1235B the respective fingers 1235A extend
and retract in the direction of arrows 1471, 1472 substantially in
unison with movement of the pusher bar 1235B while the fingers
1235A whose locking mechanisms 1410 are engaged with, for example,
the frame 1200 remain substantially stationary relative to the
frame 1200.
[0039] In another exemplary embodiment, the transfer arm 1235 may
include a drive bar 1235D or other suitable drive member. The drive
bar 1235D may be configured so that it does not directly contact a
load carried on the bot 110. The drive bar 1235D may be driven by a
suitable drive so that the drive bar 1235D travels in the direction
of arrows 1471, 1472 in a manner substantially similar to that
described above with respect to the pusher bar 1235B. In this
exemplary embodiment, the locking mechanisms 1410 may be configured
to latch on to the drive bar 1235D so that the respective fingers
1235A may be extended and retracted independent of the pusher bar
and vice versa. In alternate embodiments the pusher bar 1235B may
include a locking mechanism substantially similar to locking
mechanism 1410 for selectively locking the pusher bar to either the
drive bar 1235D or the frame 1200 where the drive bar is configured
to cause movement of the pusher bar 1235B when the pusher bar 1235B
is engaged with the drive bar 1235D.
[0040] In one exemplary embodiment, the pusher bar 1235B may be a
one-piece bar that spans across all of the fingers 1235A. In other
exemplary embodiments, the pusher bar 1235B may be a segmented bar
having any suitable number of segments 1235B1, 1235B2. Each segment
1235B1, 1235B2 may correspond to the groups of one or more fingers
1235A such that only the portion of the pusher bar 1235B
corresponding to the finger(s) 1235A that are to be
extended/retracted is moved in the direction of arrows 1471, 1472
while the remaining segments of the pusher bar 1235B remain
stationary so as to avoid movement of a load located on the
stationary fingers 1235A.
[0041] The fingers 1235A of the transfer arm 1235 may be spaced
apart from each other by a predetermined distance so that the
fingers 1235A are configured to pass through or between
corresponding support legs 620L1, 620L2 of the storage shelves 600
(FIG. 5A) and corresponding support fingers 910 of the shelves 730
on the multilevel vertical conveyors 150A, 150B. In alternate
embodiments the fingers 1235A may be configured to pass through
corresponding support fingers of bot transfer stations for passing
the bot load to multilevel vertical conveyor through the bot
transfer station. The spacing between the fingers 1235A and a
length of the fingers of the transfer arm 1235 allows an entire
length and width of the loads being transferred to and from the bot
110 to be supported by the transfer arm 1235.
[0042] The transfer arm 1235 may include any suitable lifting
device(s) 1235L configured to move the transfer arm 1235 in a
direction 1350 (FIG. 13B) substantially perpendicular to a plane of
extension/retraction of the transfer arm 1235.
[0043] Referring also to FIGS. 5A-5C, in one example, a load
(substantially similar to loads 750-753) is acquired from, for
example, a storage shelf 600 by extending the fingers 1235A of the
transfer arm 1235 into the spaces 620S between support legs 620L1,
620L2 of the storage shelf 600 and under one or more target items
1500 located on the shelf 600. The transfer arm lift device 1235L
is suitably configured to lift the transfer arm 1235 for lifting
the one or more target items 1500 off of the shelf 600. The fingers
1235A are retracted so that the one or more target items are
disposed over the payload area 1230 of the bot 110. The lift device
1235L lowers the transfer arm 1235 so the one or more target items
are lowered into the payload area 1230 of the bot 110. In alternate
embodiments, the storage shelves 600 may be configured with a lift
motor for raising and lowering the target items where the transfer
arm 1235 of the bot 110 does not include a lift device 1235L. FIG.
5B illustrates an extension of three of the fingers 1235A for
transferring a load 1501. FIG. 5C shows a shelf 1550 having two
items or loads 1502, 1503 located side by side. In FIG. 5C, three
fingers 1235A of the transfer arm 1235 are extended for acquiring
only load 1502 from the shelf 1550. As can be seen in FIG. 5C, it
is noted that the loads carried by the bots 110 may include cases
of individual items (e.g. load 1502 includes two separate boxes and
load 1503 includes three separate boxes). It is also noted that in
one exemplary embodiment the extension of the transfer arm 1235 may
be controlled for retrieving a predetermined number of items from
an array of items. For example, the fingers 1235A in FIG. 5C may be
extended so that only item 1502A is retrieved while item 1502B
remains on the shelf 1550. In another example, the fingers 1235A
may be extended only part way into a shelf 600 (e.g. an amount less
than the depth D of the shelf 600) so that a first item located at,
for example, the front of the shelf (e.g. adjacent the picking
aisle) is picked while a second item located at the back of the
shelf, behind the first item, remains on the shelf.
[0044] As noted above the bot 110 may include a retractable fence
1235F. Referring to FIGS. 6A-6D, the fence 1235F may be movably
mounted to the frame 1200 of the bot 110 in any suitable manner so
that the loads, such as load 1600, pass over the retracted fence
1235F as the loads are transferred to and from the bot payload area
1230 as can be seen in FIG. 6A. Once the load 1600 is located in
the payload area 1230, the fence 1235F may be raised or extended by
any suitable drive motor 1610 so that the fence 1235F extends above
the fingers 1235A of the bot 110 for substantially preventing the
load 1600 from moving out of the payload area 1230 as can be seen
in FIG. 6B. The bot 110 may be configured to grip the load 1600 to,
for example, secure the load during transport. For example, the
pusher bar 1235B may move in the direction of arrow 1620 towards
the fence 1235F such that the load 1600 is sandwiched or gripped
between the pusher bar 1235B and the fence 1235F as can be seen in
FIGS. 6C and 6D. As may be realized, the bot 110 may include
suitable sensors for detecting a pressure exerted on the load 1600
by the pusher bar 1235B and/or fence 1235F so as to prevent
damaging the load 1600. In alternate embodiments, the load 1600 may
be gripped by the bot 110 in any suitable manner.
[0045] Referring again to FIGS. 4B and 4C, the bot 110 may include
a roller bed 1235RB disposed in the payload area 1230. The roller
bed 1235RB may include one or more rollers 1235R disposed
transversely to the longitudinal axis 1470 of the bot 110. The
rollers 1235R may be disposed within the payload area 1230 such
that the rollers 1235R and the fingers 1235A are alternately
located so that the fingers 1235A may pass between the rollers
1235R for transferring items to and from the payload area 1230 as
described above. One or more pushers 1235P may be disposed in the
payload area 1230 such that a contact member of the one or more
pushers 1235P extends and retracts in a direction substantially
perpendicular to the axis of rotation of the rollers 1235R. The one
or more pushers 1235P may be configured to push the load 1600 back
and forth within the payload area 1230 in the direction of arrow
1266 (e.g. substantially parallel to the longitudinal axis 1470 of
the bot 110) along the rollers 1235R for adjusting a position of
the load 1600 longitudinally within the payload area 1230. In
alternate embodiments, the rollers 1235R may be driven rollers such
that a controller of, for example, the bot drives the rollers for
moving the load 1600 such that the load is positioned at a
predetermined location within the payload area 1230. In still other
alternate embodiments the load may be moved to the predetermined
location within the payload area in any suitable manner. The
longitudinal adjustment of the load 1600 within the payload area
1230 may allow for positioning of the loads 1600 for transferring
the loads from the payload area to, for example, a storage location
or other suitable location such as the multilevel vertical
conveyors 150A, 150B or bot transfer stations 140A, 140B.
[0046] Referring now to FIG. 7, the control system 1220 of the bot
will be described. The control system 1220 may be configured to
provide communications, supervisory control, bot localization, bot
navigation and motion control, case sensing, case transfer and bot
power management. In alternate embodiments the control system 1220
may be configured to provide any suitable services to the bot 110.
The control system 1220 may include any suitable programs or
firmware configured for performing the bot operations described
herein. The control system 1220 may be configured to allow for
remote (e.g. over a network) debugging of the bot. In one example,
the firmware of the bot may support a firmware version number that
can be communicated over, for example, the network 180 so the
firmware may be suitably updated. The control system 1220 may allow
for assigning a unique bot identification number to a respective
bot 110 where the identification number is communicated over the
network 180 (FIG. 1) to, for example, track a status, position or
any other suitable information pertaining to the bot 110. In one
example, the bot identification number may be stored in a location
of the control system 1220 such that the bot identification number
is persistent across a power failure but is also changeable.
[0047] In one exemplary embodiment, the control system 1220 may be
divided into a front end 1220F (FIG. 2) and back end 1220B (FIG. 2)
having any suitable subsystems 1702, 1705. The control system 1220
may include an on-board computer 1701 having, for example, a
processor, volatile and non-volatile memory, communication ports
and hardware interface ports for communicating with the on-board
control subsystems 1702, 1705. The subsystems may include a motion
control subsystem 1705 and an input/output subsystem 1702. In
alternate embodiments, the bot control system 1220 may include any
suitable number of portions/subsystems.
[0048] The front end 1220F may be configured for any suitable
communications (e.g. synchronous or asynchronous communications
regarding bot commands, status reports, etc.) with the control
server 120. The communications between the bot 110 and the control
server 120 may, in one exemplary embodiment, provide for a
substantially automatic bootstrap from, for example, initial
installation of the bot 110, operational failure of the bot 110
and/or bot replacement. For example, when a bot 110 is initialized,
the bot may obtain an identification number and subscribe to a bot
proxy 2680 (FIG. 26A) via communication with the front end 1220F.
This allows the bot to become available for receiving tasks. The
front end 1220F may receive and decompose tasks assigned to the bot
110 and reduce the task into primitives (e.g. individual commands)
that the back end 1220B can understand. In one example, the front
end 1220F may consult any suitable resources such as, for example,
a map of the storage structure 130 (FIG. 1) to decompose a task
into the primitives and to determine the various movement related
parameters (e.g. velocity, acceleration, deceleration, etc.) for
each portion of the task. The front end 1220F may pass the
primitives and movement related parameters to the back end 1220B
for execution by the bot 110. The bot front end 1220F may be
configured as a pair of state machines where a first one of the
state machines handles communication between the front end 1220F
and the control server 120 and a second one of the state machines
handles communication between the front end 1220F and the back end
1220B. In alternate embodiments the front end 1220F may have any
suitable configuration. The first and second state machines may
interact with each other by generating events for each other. The
state machines may include a timer for handling timeouts such as
during, transfer deck 130B access. In one example, when a bot 110
is entering a transfer deck 130B (e.g. FIG. 8), a bot proxy of the
central system control computers may inform the front end 1220F of
a predetermined entrance time that the bot is to enter the transfer
deck 130B. The front end 1220F may start the timer of the state
machines according to a time the bot is to wait (based on the
predetermined entrance time) before entering the deck. It is noted
that the timers (e.g. clocks) of the state machines and the bot
proxy 2680 may be synchronized clocks so as to substantially avoid
collisions between bots travelling on the transfer deck 130B and
bots entering the transfer deck 130B.
[0049] The back end 1220B may be configured to effect the functions
of the bot described above (e.g. lowering the casters, extending
the fingers, driving the motors, etc.) based on, for example, the
primitives received from the front end 1220F. In one example, the
back end 122B may monitor and update bot parameters including, but
not limited to, bot position and velocity and send those parameters
to the bot front end 1220F. The front end 1220F may use the
parameters (and/or any other suitable information) to track the
bot's 110 movements and determine the progress of the bot task(s).
The front end 1220F may send updates to, for example, the bot proxy
2680 so that the control server 120 can track the bot movements and
task progress and/or any other suitable bot activities.
[0050] The motion control subsystem 1705 may be part of the back
end 1220B and configured to effect operation of, for example, the
drive motors 1211M, 1212M, 1235L, 1495, 1490, 1610 of the bot 110
as described herein. The motion control subsystem 1705 may be
operatively connected to the computer 1701 for receiving control
instructions for the operation of, for example, servo drives (or
any other suitable motor controller) resident in the motion control
subsystem 1705 and subsequently their respective drive motors
1211M, 1212M, 1235L, 1495, 1490, 1610. The motion control subsystem
1705 may also include suitable feedback devices, such as for
example, encoders, for gathering information pertaining to the
drive motor operation for monitoring, for example, movement the
transfer arm 1235 and its components (e.g. when the fingers 1235A
are latched to the pusher bar, a location of the pusher bar,
extension of the fence, etc.) or the bot 110 itself. For example,
an encoder for the drive motors 1211M, 1212M may provide wheel
odometry information, and encoders for lift motor 1235L and
extension motor 1495 may provide information pertaining to a height
of the transfer arm 1235 and a distance of extension of the fingers
1235A. The motion control subsystem 1705 may be configured to
communicate the drive motor information to the computer 1701 for
any suitable purpose including but not limited to adjusting a power
level provided to a motor.
[0051] The input/output subsystem 1702 may also be part of the back
end 1220B and configured to provide an interface between the
computer 1701 and one or more sensors 1710-1716 of the bot 110. The
sensors may be configured to provide the bot with, for example,
awareness of its environment and external objects, as well as the
monitor and control of internal subsystems. For example, the
sensors may provide guidance information, payload information or
any other suitable information for use in operation of the bot 110.
For exemplary purposes only, the sensors may include a bar code
scanner 1710, slat sensors 1711, line sensors 1712, case overhang
sensors 1713, arm proximity sensors 1714, laser sensors 1715 and
ultrasonic sensors 1716.
[0052] The bar code scanner(s) 1710 may be mounted on the bot 110
in any suitable location. The bar code scanners(s) 1710 may be
configured to provide an absolute location of the bot 110 within
the storage structure 130. The bar code scanner(s) 1710 may be
configured to verify aisle references and locations on the transfer
decks by, for example, reading bar codes located on, for example
the transfer decks, picking aisles and transfer station floors to
verify a location of the bot 110. The bar code scanner(s) 1710 may
also be configured to read bar codes located on items stored in the
shelves 600.
[0053] The slat sensors 1711 may be mounted to the bot 110 at any
suitable location. The slat sensors 1711 may be configured to count
the slats or legs 620L1, 620L2 of the storage shelves 600 (e.g.
FIG. 5A) for determining a location of the bot 110 with respect to
the shelving of, for example, the picking aisles 130A. The slat
information may be used by the computer 1701 to, for example,
correct the bot's odometry and allow the bot 110 to stop with its
fingers 1235A positioned for insertion into the spaces between the
legs 620L1, 620L2. In one exemplary embodiment, the bot may include
slat sensors 1711 on the drive end 1298 and the driven end 1299 of
the bot to allow for slat counting regardless of which end of the
bot is facing the direction the bot is travelling. The slat sensors
1711 may be any suitable sensors such as, for example, close range
triangulation or "background suppression" sensors. The slat sensors
1711 may be oriented on the bot 110 so that the sensors see down
into the slats and ignore, for example, the thin edges of the legs
620L1, 620L2. For exemplary purposes only, in one exemplary
embodiment the slat sensors 1711 may be mounted at about a 15
degree angle from perpendicular (relative to the longitudinal axis
1470 (FIG. 4B) of the bot 110). In alternate embodiments the slat
sensors 1711 may be mounted on the bot in any suitable manner.
[0054] The line sensors 1712 may be any suitable sensors mounted to
the bot in any suitable location, such as for exemplary purposes
only, on bumpers 1273 (FIG. 2) disposed on the drive and driven
ends of the bot 110. For exemplary purposes only, the line sensors
may be diffuse infrared sensors. The line sensors 1712 may be
configured to detect guidance lines provided on, for example, the
floor of the transfer decks 130B (e.g. FIG. 8). The bot 110 may be
configured to follow the guidance lines when travelling on the
transfer decks 130B and defining ends of turns when the bot is
transitioning on or off the transfer decks 130B. The line sensors
1712 may also allow the bot 110 to detect index references for
determining absolute localization where the index references are
generated by crossed guidance lines. In this exemplary embodiment
the bot 110 may have about six line sensors 1712 but in alternate
embodiments the bot 110 may have any suitable number of line
sensors.
[0055] The case overhang sensors 1713 may be any suitable sensors
that are positioned on the bot to span the payload area 1230
adjacent the top surface of the fingers 1235A. The case overhang
sensors 1713 may be disposed at the edge of the payload area 1230
to detect any loads that are at least partially extending outside
of the payload area 1230. In one exemplary embodiment, the case
overhang sensors 1713 may provide a signal to the computer 1701
(when there is no load or other items obstructing the sensor)
indicating that the fence 1235F may be raised for securing the
load(s) within the payload area 1230. In other exemplary
embodiments, the case overhang sensors 1713 may also confirm a
retraction of the fence 1235F before, for example, the fingers
1235A are extended and/or a height of the transfer arm 1235 is
changed.
[0056] The arm proximity sensors 1714 may be mounted to the bot 110
in any suitable location, such as for example, on the transfer arm
1235. The arm proximity sensors 1714 may be configured to sense
objects around the transfer arm 1235 and/or fingers 1235A of the
transfer arm 1235 as the transfer arm 1235 is raised/lowered and/or
as the fingers 1235A are extended/retracted. Sensing objects around
the transfer arm 1235 may, for exemplary purposes only,
substantially prevent collisions between the transfer arm 1235 and
objects located on, for example, shelves 600 (e.g. FIG. 5A) or the
horizontal and/or vertical supports of the storage structure
130.
[0057] The laser sensors 1715 and ultrasonic sensors 1716
(collectively referred to as case sensors) may be configured to
allow the bot 110 to locate itself relative to each case unit
forming the load carried by the bot 110 before the case units are
picked from, for example, the storage shelves 600 and/or multilevel
vertical conveyor (or any other location suitable for retrieving
payload). The case sensors may also allow the bot to locate itself
relative to empty storage locations for placing case units in those
empty storage locations. This location of the bot relative to the
case units to be picked and/or empty storage locations for placing
the case units may be referred to as bot localization, which will
be described in greater detail below. The case sensors may also
allow the bot 110 to confirm that a storage slot (or other load
depositing location) is empty before the payload carried by the bot
is deposited in, for example, the storage slot. In one example, the
laser sensor 1715 may be mounted to the bot at a suitable location
for detecting edges of items to be transferred to (or from) the bot
110. The laser sensor 1715 may work in conjunction with, for
example, retro-reflective tape (or other suitable reflective
surface, coating or material) located at, for example, the back of
the shelves 600 to enable the sensor to "see" all the way to the
back of the storage shelves 600. The reflective tape located at the
back of the storage shelves allows the laser sensor 1715 to be
substantially unaffected by the color, reflectiveness, roundness or
other suitable characteristics of the items located on the shelves
600. The ultrasonic sensor 1716 may be configured to measure a
distance from the bot 110 to the first item in a predetermined
storage area of the shelves 600 to allow the bot 110 to determine
the picking depth (e.g. the distance the fingers 1235A travel into
the shelves 600 for picking the item(s) off of the shelves 600).
One or more of the case sensors may allow for detection of case
orientation (e.g. skewing of cases within the storage shelves 600)
by, for example, measuring the distance between the bot 110 and a
front surface of the case units to be picked as the bot 110 comes
to a stop adjacent the case units to be picked. The case sensors
may allow verification of placement of a case unit on, for example,
a storage shelf 600 by, for example, scanning the case unit after
it is placed on the shelf.
[0058] It is noted that the computer 1701 and its subsystems 1702,
1705 may be connected to a power bus for obtaining power from, for
example, the capacitor 1400 through any suitable power supply
controller 1706. It is noted that the computer 1701 may be
configured to monitor the voltage of the capacitor 1400 to
determine its state of charge (e.g. its energy content). In one
exemplary embodiment, the capacitor may be charged through charging
stations located at, for example, one or more transfer areas 295
(FIGS. 8 and 11A-11E) or at any other suitable location of the
storage structure 130 so that the bot is recharged when
transferring payloads and remains in substantially continuous use.
The charging stations may be configured to charge the capacitor
1400 within the time it takes to transfer the payload of the bot
110. For exemplary purposes only, charging of the capacitor 1400
may take about 15 seconds. In alternate embodiments, charging the
capacitor may take more or less than about 15 seconds. During
charging of the capacitor 1400 the voltage measurement may be used
by the computer 1701 to determine when the capacitor is full and to
terminate the charging process. The computer 1701 may be configured
to monitor a temperature of the capacitor 1400 for detecting fault
conditions of the capacitor 1400.
[0059] The computer 1701 may also be connected to a safety module
1707 which includes, for example, an emergency stop device 1311
(FIG. 3A) which when activated effects a disconnection of power to,
for example, the motion control subsystem 1705 (or any other
suitable subsystem(s) of the bot) for immobilizing or otherwise
disabling the bot 110. It is noted that the computer 1701 may
remain powered during and after activation of the emergency stop
device 1311. The safety module 1707 may also be configured to
monitor the servo drives of the motion control subsystem 1705 such
that when a loss of communication between the computer and one or
more of the servo drives is detected, the safety module 1707 causes
the bot to be immobilized in any suitable manner. For example, upon
detection of a loss of communication between the computer 1701 and
one or more servo drives the safety module 1707 may set the
velocity of the drive motors 1211M, 1212M to zero for stopping
movement of the bot 110.
[0060] The communication ports of the control system 1220 may be
configured for any suitable communications devices such as, for
example, a wireless radio frequency communication device 1703
(including one or more antennae 1310) and any suitable optical
communication device 1704 such as, for example, an infrared
communication device. The wireless radio frequency communication
device 1703 may be configured to allow communication between the
bot 110 and, for example, the control server 120 and/or other
different bots 110 over any suitable wireless protocol. For
exemplary purposes only, the wireless protocol for communicating
with the control server 120 may be the wireless 802.11 network
protocol (or any other suitable wireless protocol). Communications
within the bot control system 1220 may be through any suitable
communication bus such as, for example, a control network area bus.
It is noted that the control server 120 and the bot control system
1220 may be configured to anticipate momentary network
communication disruptions. For example, the bot may be configured
to maintain operation as long as, for example, the bot 110 can
communicate with the control server 120 when the bot 110 transits a
predetermined track segment and/or other suitable way point. The
optical communication device 1704 may be configured to communicate
with, for example, the bot transfer stations for allowing
initiation and termination of charging the capacitor 1400. The bot
110 may be configured to communicate with other bots 110 in the
storage and retrieval system 100 to form a peer-to-peer collision
avoidance system so that bots can travel throughout the storage and
retrieval system 100 at predetermined distances from each other in
a manner substantially similar to that described in U.S. patent
application Ser. No. 12/757,337, entitled "CONTROL SYSTEM FOR
STORAGE AND RETRIEVAL SYSTEMS," with Attorney Docket Number
1127P013888-US (PAR), previously incorporated by reference herein
in its entirety.
[0061] Referring to FIGS. 2, 4B and 8-13B, bot navigation and
motion control will be described. Generally, in accordance with the
exemplary embodiments, the bot 110 has, for example, three modes of
travel. In alternate embodiments the bot 110 may have more than
three modes of travel. For exemplary purposes only, in the picking
aisles 130A the bot travels on wheels 1211-1214 (or lockable
casters 1260', 1261' in lieu of idler wheels 1213, 1214) and is
guided by guide wheels 1250-1253 against the sides of track 1300
(FIG. 3B). On the transfer deck 130B, the bot 110 uses casters
1261, 1262 (or releases lockable casters 1260', 1261') while making
substantially right angle turns when transitioning from/to the
picking aisles 130A or transfer stations 140A, 140B. For traveling
long distances on, for example, the transfer deck 130B the bot 110
travels on wheels 1211-1214 (or lockable casters 1260', 1261' in
lieu of idler wheels 1213, 1214 where the casters 1260', 1261' are
rotationally locked as described above) using a "skid steering"
algorithm (e.g. slowing down or stopping rotation of one drive
wheel relative to the other drive wheel to induce a turning motion
on the bot) to follow guidance lines 1813-1817 on the transfer deck
130B.
[0062] When traveling in the picking aisles 130A, the bot 110
travels in substantially straight lines. These substantially
straight line moves within the picking aisles 130A can be in either
direction 1860, 1861 and with either bot orientation (e.g. a
forward orientation with the drive end 1298 trailing the direction
of travel and a reverse orientation with the drive end 1298 leading
the direction of travel). During straight line motion on the
transfer deck 130B the bot 110 travels in, for exemplary purposes
only, a counterclockwise direction 1863, with a forward bot
orientation. In alternate embodiments the bot may travel in any
suitable direction with any suitable bot orientation. In still
other alternate embodiments, there may be multiple travel lanes
allowing bots to travel in multiple directions (e.g. one travel
lane has a clockwise direction of travel and another travel lane
has a counter-clockwise direction of travel). In one example, the
turns to and from the picking aisles 130A and/or transfer areas 295
are about 90 degrees where the center point of rotation P of the
bot is located substantially midway between the drive wheels 1211,
1212 such that the bot can rotate clockwise or counterclockwise. In
alternate embodiments the bot turns may be more or less than about
90 degrees. In another example, the bot may make a substantially
180 degree turn (i.e. two substantially 90 degree turns made in
sequence without a stop) as will be described below.
[0063] As described above, the transfer deck 130B may include
guidance lines 1810-1817 for guiding the bot 110. The guidance
lines 1810-1817 may be any suitable lines adhered to, formed in or
otherwise affixed to the transfer deck 130B. For exemplary purposes
only, in one example the guidance lines may be a tape affixed to
the surface of the transfer deck 130B. In this exemplary embodiment
the transfer deck 130B includes a track 1800 having a first side
1800A and a second side 1800B separated by a wall 1801. The first
and second sides 1800A, 1800B of the track 1800 are joined by end
track sections 1800E (only one of which is shown in FIG. 8). In
alternate embodiments the track 1800 may have any suitable
configuration. Each of the first and second sides 1800A, 1800B
includes two travel lanes defined by, for example, guidance lines
1813, 1814 and 1816, 1817 respectively. The end track portions
1800E include, for example, one travel lane defined by, for
example, guidance line 1815. In alternate embodiments the
sections/sides of the track 1800 may have any suitable number of
travel lanes defined in any suitable manner. In accordance with the
exemplary embodiments each picking lane 130A and/or transfer area
295, includes a lead in/out guidance line 1810-1812. The lead
in/out guidance lines 1810-1812 and the single guidance line 1815
of the end track portions 1800E may be detected by the bot 110 as
index marks for bot localization during long line-following moves.
The lead in/out guidance lines 1810-1812 and guidance line 1815 may
also be detected by the bot 110 as reference marks for making
turns.
[0064] When the bot 110 moves in substantially straight lines, such
as in the picking aisles 130A and/or transfer areas 295, the drives
for motors 1211M, 1212M may be configured as torque controllers.
For example, the computer 1701 may be configured to close a
velocity loop as shown in FIG. 10 using the average of the velocity
feedback from both wheels 1211, 1212 as the "bot velocity". To
improve performance and avoid velocity loop instabilities, the
velocity loop may be augmented with torque-feedforward and operated
at a low gain. The computer 1701 may also be configured to close a
position loop as also shown in FIG. 10 for final position at a stop
location of the bot 110. The computer 1701 may also be configured
to sum in a differential torque offset to implement line following.
It is noted that the drive wheels 1211, 1212 may loose traction
with the transfer deck 130A or floor of a picking aisle 130A or
transfer area 295 when the flooring surfaces and/or the wheels are
contaminated with liquids, dirt or other particulates. The velocity
control loop may be configured to mitigate the loss of traction by
backing off the torque to both wheels 1211, 1212 whenever feedback
provided by, for example, an encoder for one or both wheels 1211,
1212 indicates a velocity higher than a predetermined velocity of
the bot 110.
[0065] When travelling long distances on, for example, the transfer
deck, the bot 110 travels on drive wheels 1211, 1212 and idler
wheels 1213, 1214 (or locked casters 1260', 1261') so that the bot
is deterred from veering off of the straight line trajectory
through the fixed nature of the drive wheels 1211, 1212 and idler
wheels 1213, 1214 (or locked casters 1260', 1261'). The computer
1701 may be configured with any suitable line following algorithm
to substantially ensure that the bot 110 maintains travel in a
straight line. The line following algorithm may also allow for
correction of initial line following errors due to, for example,
misalignment from turns. In one exemplary embodiment the bot 110
uses line sensors 1712 to estimate its heading and offset from a
guidance line 1810-1817. The bot 110 may be configured to use, for
example, any suitable algorithm such as a fuzzy logic algorithm to
generate corrections in the travel path of the bot 110. The
correction may be applied as a differential torque to the wheels as
the bot is travelling (e.g. skid steering--rotating one drive wheel
slower than the other drive wheel to produce increased drag on one
side of the bot for inducing a turning moment on the bot).
[0066] For turns, such as for example, substantially right angle
turns, the drives for motors 1211M, 1212M may be configured as
position controllers. For example the drives may be commanded by
the computer 1701 to rotate their respective wheels in opposite
directions for a predetermined distance to generate a pivot turn of
slightly more than about 90 degrees. When for example, line sensors
1712 detect a stopping guidance line, the turning move is
terminated. In alternate embodiments the drives for the motors
1211M, 1212M may be operated in any suitable manner for driving the
bot in substantially straight lines or during turns.
[0067] FIGS. 9A and 9B illustrate an exemplary turn sequence for a
substantially 90 degree turn made by the bot 110 while
transitioning onto the transfer deck 130B from a picking aisle
130A. In this example, the bot is traveling in a forward
orientation in the direction of arrow 1910. As the bot 110 exits
the picking aisle 130A, the bot 110 lowers the casters 1260, 1261
(FIG. 4A) so that the idler wheels 1213, 1214 are lifted off of the
transfer deck 130B (or unlocks casters 1260', 1261'). Using line
sensors 1712 located at for example the driven end 1299 of the bot
110, the bot 110 detects the inner travel lane guidance line 1814
and then using corrected wheel odometry, stops with its pivot point
P at or close to the outer travel lane guidance line 1813. The bot
110 rotates about 90 degrees in the direction of arrow 1920 using a
differential torque in the drive motors 1211M, 1212M to turn the
drive wheels 1211, 1212 in opposite directions such that the bot
110 rotates about point P. The bot 110 detects the guidance line
1813 with the line sensors 1712 and terminates the turn. The bot
110 raises the casters 1260, 1260 so that the idler wheels 1213,
1214 contact the transfer deck 130B (or locks casters 1260', 1261')
and proceeds to follow guidance line 1813 using, for example, line
following. It is noted that turning of the bot to enter, for
example, picking aisle 130A may occur in substantially the same
manner as that described above for exiting the picking aisle
130A.
[0068] FIGS. 11A-13B illustrate exemplary travel paths of a bot 110
including straight line travel and turn sequences. It is noted that
while the specific examples of bot travel are shown and described,
the bot 110 may be configured to perform any suitable number of
turns and transition between any suitable number of travel lanes in
any suitable manner for travelling throughout a respective level of
the storage structure 130. FIG. 11A illustrates a travel path of
the bot 110 where the bot 110 transitions from one, for example,
picking aisle (or transfer station), across the transfer deck 130B
and into a transfer area 295 (or other picking aisle) with the bot
110 transitioning from a reverse orientation (e.g. drive end 1298
leading) to a forward orientation (e.g. drive end 1298 trailing).
In this example, the bot 110 exits the picking aisle 130A in a
reverse orientation such that a line sensor(s) 1712 disposed
substantially at pivot point P detects the inner travel lane
guidance line 1814. The bot 110 pivots about point P in a
counterclockwise direction in a manner substantially similar to
that described above with respect to FIGS. 9A and 9B. The bot
follows guidance line 1814 in a forward orientation until, for
example, line sensors 1712 (located proximately to or at one or
more of the drive end 1298 and driven end 1299 of the bot 110)
detect the crossing of guidance lines 1814 and 1815 (FIG. 8) at
which point the bot 110 pivots counterclockwise about point P in a
manner similar to that described above so that the bot follows line
1815 substantially to a point where guidance line 1815 crosses the
inner travel lane guidance line 1816. At the crossing of guidance
lines 1815, 1816 the bot 110 pivots counterclockwise to follow
guidance line 1816. The bot follows guidance line 1816 until the
line sensors 1712 detect a crossing of guidance lines 1816 and 1812
at which point the bot pivots clockwise to enter transfer area 295
in a forward orientation.
[0069] FIG. 11B illustrates an exemplary travel path of the bot 110
where the bot exits the picking aisle 130A in a reverse orientation
and enters transfer area 295 in a reverse orientation. In this
example, the motion of the bot is substantially similar to that
described above with respect to FIG. 11A, however, after travelling
around wall 1801 the bot transitions to the outer travel lane
guidance line 1817 so that the bot 110 is in a reverse orientation.
The reverse orientation of the bot 110 allows the bot to pivot
counterclockwise into an open area of the transfer deck 130B for
entering the transfer area 295 in a forward orientation without
colliding with the outside wall 2100 of the transfer deck 130B.
[0070] FIG. 11C illustrates the bot 110 exiting the picking aisle
130A in a forward orientation and entering transfer area 295 in a
forward orientation. The motion of the bot is substantially similar
to that described above however, in this example, the bot 110
transitions from outer travel lane guidance line 1813 to inner
travel lane guidance line 1816 so that the bot can enter the
transfer area 295 in a forward orientation.
[0071] FIGS. 11D and 11E illustrate the bot 110 exiting the picking
aisle 130A in a forward orientation and entering the transfer area
295 in a reverse orientation using the outer travel lane guidance
lines 1813 and 1817. The motion of the bot 110 may be substantially
similar to that described above, however as the bot 110 travels
along guidance line 1815 the bot 110 makes three turns 2110-2112
(e.g. where turns 2110, 2111 turn the bot substantially 180 degrees
along guidance line 1815) to orient the bot 110 for making the
final turn 2113 into the transfer area 295. As can be seen in FIG.
11E, without the additional turn the bot 110 would not be able to
transition from outer travel lane guidance line 1813 onto outer
travel lane guidance line 1817 without colliding with the outer
wall 2100 (as indicated by the shaded area) using line following as
described herein.
[0072] FIGS. 12A and 12B illustrate an exemplary travel path of bot
110 from picking aisle 130A1 to picking aisle 130A2 where travel of
the bot 110 within the picking aisle 130A1 is in a forward
orientation and travel within picking aisle 130A2 is in a reverse
orientation. In this example, the bot uses the outer travel lane
guidance line 1813 for transitioning between picking aisles 130A1,
130A2. As can be seen in FIG. 12A when travelling along the outer
travel lane guidance line 1813 and entering picking aisle 130A2 the
bot pivots in a direction so the driven end 1299 of the bot swings
towards the inner travel lane of the transfer deck 130B so as to
avoid colliding with the outer wall 2100 as shown in FIG. 12B.
[0073] FIGS. 13A and 13B illustrate an exemplary travel path of bot
110 from picking aisle 130A1 to picking aisle 130A2 where travel of
the bot 110 within the picking aisles 130A1, 130A2 is in a reverse
orientation. In this example, the bot uses the inner travel lane
guidance line 1814 for transitioning between picking aisles 130A1,
130A2. As can be seen in FIG. 13A when travelling along the inner
travel lane guidance line 1814 the bot pivots in a direction so the
driven end 1299 of the bot swings towards the outer travel lane of
the transfer deck 130B so as to avoid colliding with the inner wall
1801 as shown in FIG. 13B.
[0074] It is noted that the bot may be configured to transition
between the tracked travel lanes of the picking aisles 130A and the
open transfer deck 130B in any suitable manner. In one exemplary
embodiment, the guidance lines 1810-1812 may guide the bot into the
tracks 1300 of the picking aisles. In alternate embodiments, one or
more of the sensors 1710-1716 may allow the bot 110 to detect, for
example, edges or other suitable features of the tracks 1300 (FIG.
3B) and position itself so the bot 110 passes between opposing
tracks 1300 with the guide wheels contacting the recesses 1300R in
the tracks 1300.
[0075] In accordance with one exemplary embodiment, in the above
described examples of the bot travel paths, when the bot is turning
the bot is supported by the drive wheels 1211, 1212 and the casters
1260, 1261 (or casters 1260', 1261'). The straight line moves of
the bot may be made with the bot supported on the drive wheels
1211, 1212 and the idler wheels 1213, 1214 (or casters 1260',
1261'). As noted above, any corrections to the bot travel path
while the bot is traveling in a straight line may be made using
skid steering. In alternate embodiments, the bot may travel in a
straight line path with the casters 1260, 1261 deployed. In still
other alternate embodiments, correction to the bots straight line
travel paths may be made through steerable wheels.
[0076] Referring again to FIG. 7, the bot 110 can determine its
position within the storage and retrieval system 100 for
transitioning through the storage structure 130 as described above
through, for example, bot localization. In one exemplary embodiment
bot localization may be derived through one or more of bot
odometrey, slat counting, index counting and bar code reading. As
described above, the bot odometry may be provided from encoders
associated with, for example, wheels 1211-1214 (FIG. 2). It is
noted that encoder information from each wheel 1211-1214 may be
averaged and scaled in any suitable manner to provide a distance
traveled by the bot. In alternate embodiments, the distance
traveled by the bot may be obtained from the wheel encoder
information in any suitable manner. The slat counting may be
provided by, for example, the slat sensors 1711 as the bot travels
through the picking aisles. The slat counting may supplement the
odometry information when the bot is within the picking aisles. The
index counting may be provided, by for example, the line sensors
1712 as the bot passes over crossed sections of the guidance lines
1810-1817 (FIG. 8). The index counting may supplement the bot
odometry when the bot is traveling on the transfer deck 130B. Bar
code reading may be provided by bar code scanner 1710. The bar code
reading may be configured to allow the bot 110 to determine an
initial position of the bot such as when the bot is powered up from
an off or dormant state. The bar codes may be located at transfer
stations 140A, 140B (FIG. 1) or any other suitable location within
the storage structure 130 for initializing the bot 110. Bar codes
may also be located within the picking aisles and on the transfer
deck to, for example, confirm bot location and correct for missed
slats or indexes. The on-board computer 1701 of the bot 110 may be
configured to use any suitable combination of bot odometrey, slat
counting, index counting and bar code reading to determine the
bot's 110 position within the storage structure 130. In alternate
embodiments, the computer 1701 may be configured to determine the
location of the bot using only one or any suitable combination of
bot odometrey, slat counting, index counting and bar code reading.
In still other alternate embodiments, the location of the bot may
be determined in any suitable manner such as through, for example,
an indoor spatial positioning system. The indoor spatial
positioning system may be substantially similar to a global
positioning system and use any suitable technique for determining
the position of an object such as, for example, acoustic, optical,
or radio frequency signaling.
[0077] In one exemplary embodiment, one or more of the sensors
1710-1716 described above may allow for dynamic positioning of bots
110 within the picking aisles 130A in any suitable manner. The
position at which the bot 110 is stopped for dynamically allocating
case units may be determined by, for example, the control server
120 (FIG. 1), the control system 1220 of the bot or by a
combination thereof. For example, dynamic allocation of the storage
space may be determined by, for example, the control server 120 in
any suitable manner such that any open storage spaces in the
storage structure 130 are filled with items having a size capable
of fitting within those open storage spaces. The control server may
communicate to the appropriate components of the storage and
retrieval system 100, for example, a location of a predetermined
storage location and an appropriately sized case unit or case units
for placement in the predetermined storage location. That case unit
may be transferred into the storage and retrieval system 100 where
a bot 110 delivers the case unit to the predetermined storage
location. As a non-limiting example, the sensors 1710-1716 of the
bots 110 may count slats 620L1, 620L2 (FIG. 5A) and/or detect edges
of case units on the storage shelves for dynamically positioning
the bots for placing the case unit in the predetermined storage
location. Dynamically positioning the bots 110 and/or the dynamic
allocation of shelf storage space may allow for the positioning of
case units having varying lengths in each storage bay 5000, 5001
(FIGS. 14A and 14B) such that the use of the storage space is
maximized. For example, FIG. 14A illustrates a storage bay 5000
divided into storage slots S1-S4 as is done in conventional storage
systems. The size of the storage slots S1-S4 may be a fixed size
dependent on a size of the largest case unit (e.g. case unit 5011)
to be stored on the shelf 600 of the storage bay 5000. As can be
seen in FIG. 14A, when case units 5010, 5012, 5013 of varying
dimensions, which are smaller than case unit 5011, are placed in a
respective storage slot S1, S2, S4 a significant portion of the
storage bay capacity, as indicated by the shaded boxes, remains
unused. In accordance with an exemplary embodiment, FIG. 14B
illustrates a storage bay 5001 having dimensions substantially
similar to storage bay 5000. In FIG. 14B the case units 5010-5016
are placed on the shelf 600 using dynamic allocation. As can be
seen in FIG. 14B, dynamically allocating the storage space allows
placement of case units 5014-5016 on shelf 600 in addition to case
units 5010-5013 (which are the same case units placed in storage
bay 5000 described above) such that the unused storage space, as
indicated by the hatched boxes, is less than the unused storage
space using the fixed slots of FIG. 14A. FIG. 14C illustrates a
side by side comparison of the unused storage space for the fixed
slots and dynamic allocation storage described above. It is noted
that the unused storage space of bay 5001 using dynamic allocation
may be decreased even further by decreasing the amount of space
between the case units 5010-5016 which may allow for placement of
additional case units on the shelf 600. As may be realized, as
items are placed within the storage structure the open storage
spaces may be analyzed, by for example the control server 120,
after each case unit placement and dynamically re-allocated
according to a changed size of the open storage space so that
additional case units having a size corresponding to (or less than)
a size of the re-allocated storage space may be placed in the
re-allocated storage space.
[0078] It should be understood that the exemplary embodiments
described herein may be used individually or in any suitable
combination thereof. It should also be understood that the
foregoing description is only illustrative of the embodiments.
Various alternatives and modifications can be devised by those
skilled in the art without departing from the embodiments.
Accordingly, the present embodiments are intended to embrace all
such alternatives, modifications and variances that fall within the
scope of the appended claims.
* * * * *