Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BACKGROUND OF TIIE INVENTION
The present invention relates to material handling trucks and has
specific reference to a self-propelled robo-t platform truck intended no-
tably for warehouses where relatively large amounts of miseellaneous ar~
ticles are stored, notably in mail-order firms.
It is nowadays current practice to keep many different a~ticles
in warehouses and to use arrays of racks separated by lanes, each rack
receiving a basket containing the stored objects.
The articles can be picked up by means of fork lift trucks under
the control of an operator, the trucks being driven along the passages
and handling the baskets filled with articles. A department entrusted
with the regrouping of the eustomer's orders subsequently pieks up the
proper articles from the baskets and conveys the selected artieles to a
dispatching department where -the goods ordered by each customer are as-
sembled and dispatched. The baskets must subsequently be returned to the
corresponding racks. Obviously, this method involves many handling opera-
tions and therefore its limits are attained very rapidly, and it cannot
be used when the number of reference articles is very high.
Under these conditions, various firms have been led to use so-
called transtockers which are special-purpose trucks. However, these
trucks are confined to a specific lane between two rows of racks. A tran-
stocker may operate automatically and according to the selected program
it is capable of selecting the proper basket containing for instance spa-
re parts disposed at a well-defined location in the reference racks.
The articles thus picked up by the transtocker are delivered by
the truek to a eentral lane extending aeross the lanes in whieh the tran-
stoekers are operated, this eentral lane being provided as a rule with
a belt conveyor for transferring the objects to a regrouping centre.
In the present state of the art, this transtoeker arrangement
constitutes the latest improvement, so far as the Applicants are aware,
However, for various reasons it is far from being completely satisfac-
tory. Thus, notably, it can handle only one reference artiele at a time,
and must therefore make a return travel each time a different item is
eoneerned, so that its time-per-eycle rate is excessively low.
Moreover, transtockers do not carry out the final packing of the
selected articles, so that a sorting step must be contemplated at the out-
put end of the store for assembling the articles pertaining to a same or-
der and then directing the assembled articles toward the packing and dis-
patching department or station. - 2 -
Another important inconvenience characterizing the above-describ-
ed metllod lies in the fact that the complete warehouse operation is most
likely to be seriously impairea in case of failure of one of the transtock-
ers.
It is also worth pointing ou-t that a robot warehouse utilizing
transtockers is designed for operation at a predetermined rate which can-
not be changed as a function of the number of customers'orders to be pro-
cessed. Thus, in certain cases where the stock turn-round is lower or
higher than this predetermined rate, the use of automatic transtockers
control means does not pay for itself.
SUMMARY OF THE INVENTION
It is the primary object of the present invention to provide a
self-propelled robot platform truck adapted to be incorporated in a fully
automatic modular system of a warehouse for handling commercial articles
or spare parts.
With the self-propelled robot platform truck of the present in-
vention it is possible to perform the three essential functions required
in the management of stock, namely :
- re-stocking or picking-up full baskets of articles or spare
parts in the storage racks,
- picking up and sorting orders concerning several articles,
- picking up, packing and adressing orders concerning a single
article.
The self-propelled robot platform truck of the present invention
is in constant communication with a central computer issuing the corres-
ponding orders to the tr~ck in connection with these various tasks.
It is another object of the present invention to provide a self-
propelled platform robot truck adapted to carry out several commercial
orders so as to minimize the number of necessary handling operations or
steps.
Furthermore, the present invention is concerned with the provision
of a self-propelled robot platform truck adapted to operate in conjunction
with a plurality of similar platform trucks in a warehouse so as to meet
any momentary requirement.
Thus, the self-propelled robot platform truck of the present in-
vention can adapt itself to small and large units according to require-
ments.
sesides, the self-propelled robot platform truck according to the
present invention is adapted to pick up articles of very different types,
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due to the use of special tool means permit-ting its adaptatlon notably
to the requirements of mail-order firms in which very different articles
are to be handled.
Other objects, features and advantages of the present invention
will appear as the following description proceeds with reference to the
accompanying drawings showing various forms of emboodiment of the inven-
tion which are given by way of illustration, not of limitation.
The self-propelled robot platform truck for warehouses in which
articles are assembled according to their specific reference mark, number
or like symbol in baskets, hoppers or dispensers disposed in arrays of
racks, for the dual purpose of re-stocking the racks and picking up se-
lected articles concerning a specific order received from a customer,
said truck, comprising a frame structure provided with a motor and unt-
ed on wheels, being adapted to travel along lanes lined on both sides
with said warehouse racks, is characterized by the fact that it comprises
means for extracting a basket, hopper or dispenser from the warehouse
racks, and an embarked store comprising several compar-tments for storing
the articles picked up from the warehouse.
THE DRAWINGS
.
FIGURE 1 illustrates in perspective view the self-propelled plat-
form truck of the present invention during its operation along a lane of
a warehouse.
FIGU~E 2 illustrates diagramnatically the self-propelled platform
truck of the present invention in its restocking version.
FIGURE 3 is a view similar to Figure 2 showing the same truck
equipped with means for picking up multifarious articles.
FIGrJRE 4 shows the self-propelled truck of this invention equipped
with means for picking up and packing articles of the same type.
FIGrJRE 5 is a front elevational view of the self-propelled robot
platform truck equipped with a handling system.
FIGURE 6 is a plane view from above of the truck of Figure 5.
FIGURES 7a and 7b are front and top views respectively for faci
litating the understanding of the de of operation of the fork-type pick-
up system.
FIGrJRES 8a and 8b are front and top views, respectively, of a
storage basket of a dular rack kept in the warehouse, according to a
preferred form of embodiment thereof.
FIGURE 9 is a front view of the pick-up head of the handling sys-
tem
-- 4
It may be emphasized that the articles are assembled or reyrouped
according to their reference marks, since a data control system is used,
so that the articles are identified by the computer according to their re-
ference marks.
The articles are assembled by groups in the baskets, hoppers 2 or
dispensers 3 according to the specific nature of the product concerned.
In general, baskets are used for tin-can articles or articles contained
in brick-like containers, the hopper is intended for loose flexible arti-
cles and the dispenser is used in general for small articles difficult to
pick up by means o~ ordinary gripping means. Of course, other form of
storage may be contemplated without departing the basic principles of the
nventlon .
The baskets 1, hoppers 2 or dispensers 3 are arranged in modular
racks 4 from which they can be extracted when necessary.
These modular racks 4 line the sides of the lanes 5 in which the
above-mentioned self-propelled robot platform trucks 6 can travel freely.
The self-propelled truck of the instant invention is self-con-
tained and according to requirements a variable number of trucks of this
type may be used in a given warehouse.
The self-propelled truck according to the prezent invention which
comprises a frame structure 7 mounted on wheels 8 is also provided with
means 9 for picking up a basket, hopper or dispenser from modular racks 4
of a warehouse or like store.
These pick-up means are bidirectional and therefore capable of
either extracting the selected basket, hopper or dispenser from a rack or
replacing the previously extracted basket, hopper or dispenser into a rack.
Moreover, the self-propelled truck according to the present inven-
tion is characteriæed by the fact that it comprises a so-called embarked
store 10 comprising several compartments for storing articlesO
The use of an embarked s-tore is attended by many advantages, nota
bly in that it minimizes the handling periods by reducing the courses. For
instance, the self-propelled truck of the instant invention is capable of
executing several orders simultaneously or restocking during its travel
the various articles in store.
The function of the self-propelled robot platform truck of the
present invention is twofold. On the one hand, it must be capable of re-
stocking the automatically controlled store and on the other hand it per-
mits of taking gooas from the store for carrying out orders~
The truck equipments may be changed according to the specific
-- 6 --
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FIGURE 10 illustrates in side elevational view with parts in
section of the pick-up head of the handling system.
FIGURES 11a and 11b illustrate diagrammatically the various steps
of the operation of the twin-wheel pick-up device.
FIGURE 12 is a top view of the self-propelled robot platform truck
of the present invention equipped with a device for packing articles of
a same and single typeO
FIGURE 13 is a front view of the self-propelled robot platform
truck of the present invention, equipped with a device for packing arti-
cles of a same and single type, and
FIGURE 14 illustrates diagrammatically the path of a self-pro-
pelled robo~ platform truck according to this invention in an automatical-
ly operated warehouse.
DESCRIPTION OF THE PREEERRED EMBODIMENTS
The present invention is directed to provide a self-propelled ro-
bot platform truck for warehouses where articles are stored by groups ac-
cording to their specific reference mark~ number or symbol in baskets,
hoppers or dispensers disposed in dular racks.
Since the present invention was developed for use in the mail-or-
der industry, the following exemplary form of embodiment relates re par-
ticularly to the general re-stocking of warehouses and the preparation of
the articles listed in each specific order by regrouping the articles to
be dispatched, the orders relating either to a single article or to seve-
ral articles. However, the present invention is applicable to a conside-
rably wider field in many industries wherein the self-propelled truck of
this invention can be used, such as spare-parts shops and the like.
As will be clearly understood from the following description, the
specific nature of the stored parts or articles is immaterial, provided
that they can be handled in a dular storage system for example of the
type comprising baskets, hoppers, dispensers or other similar means.
The self-propelled robot platform truck according to the present
invention is intended for incorp~ration in a fully automatic warehouse
control system nitored by a central computer.
The various duties devolved to the self-propelled truck of the
present invention are determined through a permanent or intermittent dia-
logue between the truck and the central computer.
Figure 1 illustrates diagrammatically a warehouse in which arti-
cles designated by specific reference numbers or signs are kept in baskets
1, hoppers 2 or dispensers 3.
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function contemplated. However, according to a preferred forrn of embodi-
ment of the truck of the present invention these equipments may be inter-
changed very rapidly to meet immediate re~uiremen-ts.
Figure 2 illustrates diagrammatically a self-propelled robot plat-
form-type material handling truck with means for restocking a warehouse.
For this purpose, the truck 6 comprises pick-up means 9 capable of extract-
ing a basket, hopper or dispenser from a modular rack in the warehouse.
On the other hand, this self-propelled truck 6 also comprises an
emharked store 10 of which the various compartments are adapted to recei-
ve a basket, hopper or dispenser similar to those utilized for storing
goods in the warehouse racks.
The pick-up means 9 may also operate in connection with the em-
barked store 10. In other words, said pick-up means are capable of re-
trieving a basket, hopper or dispenser from this embarked store 10 and
replacing it into this store.
The mode of operation of the self-propelled truck 9 in its re-
stocking version is as follows : the truck travelling along the warehouse
lanes is stopped in front of the rack containing an empty basket. The
pich-up means 9 are then actuated for extracting this empty basket and in-
troducing it into the embarked store 10. Then, the same pick-up means 9
take from the embarked store another basket filled with articles and in-
troduces this full basket into the rack as a substitute for the empty
basket. As a rule, the embarked store comprises a plurality of compart-
ments and consequently the warehouse can be restocked very rapidly,
Fiyure 3 illustrates diagrammatically a self-propelled robot plat-
form truck adapte~ to pick up several articles. For this purpose, the
-truck 6 comprises pick-up means 9 adapted to extract or replace a basket,
hopper or dispenser from and into dular racks of the warehouse. More-
over, the pick-up means comprise a handling system 11 adapted to pick up
an article from a basket, hopper or dispenser supported by said pick up
means 9.
The self-propelled truck 6 further comprises an embarked store 10
containing baskets for regrouping the various articles of a same order.
These regrouping baskets are adapted to be introduced into, or taken from,
the embarked store 10 by operating the pick-up means 9. This self-pro-
pelled truck operates as follows :
The truck travels along the warehouse lanes and stops in front of
the rack housing the basket containing one of the articles necessary for
completing a given order. The pick-up means 9 take the basket concerned
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Erom its rack and the handling system 11 picks up the article concernedfrom the basket. When this article has been properly gripped by the hand-
ling system 11, the basket is replaced into the rack and the pick-up means
9 are actuated for extracting -the basket for regrouping the articles of a
same given order from the rack. Then~ the handling system 11 drops the
ordered article into the regrouping basket and the pick-up means.return
the basket for regrouping the ordered article in the embarked store 10.
It will be seen that just after the basket has been re-introduced
into the rack, the self-propelled truck 6 can move again in the warehouse
for picking up another basket, the ordered article being delivered to the
regrouping basket during the movement of the truck from one ~tation to an-
other. Thus, some of the steps take place simultaneously, so that an ap-
preciable amount of time is saved.
Since the embarked store 10 can hold several order-regrouping bas-
kets, the self-propelled truck can carry out several orders simultaneous-
ly .
Figure 4 shows the self-propelled truck 6 of the present invention
in its version corresponding to the picking up of single articles. In this
case, the truck is provided with pick-up means 9 and also with a handling
system 11 simllar to the system described with reference to Figure 3, so
that unitary articles can be picked up from the proper storage baskets
supported by the racks. Besides, since the order to be executed refers to
only one station per article, the truck 6 is provided with a bagging de-
vice 12 to which the selected article is fed. Therefore, the container
~or a carriage 44, see Figures 12, 13) disposed downstream of the bagging
device 12 receives packed articles ready for dispatching.
Figures 5 and 6 illustrate a front view and a plane view from a-
bove, respectively, of a self-propelled robot platform truck according to
the present invention, intended more particularly for restocking opera-
tions and picking up multifarious articles.
This self-propelled truck comprises a motorized frame 7 mounted
on wheels 8. According to a specific feat~lre of the present invention, the
motor is an electric motor energized by means of storage batteries 13
adapted to be recharged periodically by means of a battery charger connect-
ed to the mains.
The pick-up means 9 consist of a set of pick-up forks 14 movable
vertically along a post 15. Thus, the pick-up forks 14 can be positioned
in the horizontal direction with respect to the racks according to the
position of the frame 7 of truck 6, and in the vertical direction by the
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position of forks 14 on said post 15 on which they are slidably mounted.
With this arrangement, the pick-up forks 14 can be brought to a
position in front of the rack containing the basket, hopper or dispenser
to be extracted, and an extractor 16 is adapted to engage the selected
basket, hopper or dispenser and cause same to slide on said forks 1~.
With a reverse movement the extractor 16 may be caused to push the basket,
hopper or dispenser back into the rack.
Figures 8a and 8b are a side view and a front view respectively
of a basket 1 for storing articles in a rack 4.
In a preferred form of embodiment the racks 4 comprise slideways
17 in which the baskets, hoppers or dispensers are disposed.
The pick-up forks 14 have a configuration somewhat similar to that
of slideways 17 and therefore the sliding movement of a basket 1 from a
rack 4 to the Eorks 14 of the truck is greatly simplified.
Figures 7a and 7b are a front view and a plane view from above,
respectively, of the pick-up means 9 of the truck of this invention. Said
pick~up means 9 comprise pick-up forks 14 adapted to be brought into a-
lignment with the slideways 17 of rack 4 in which the basket containing
the articles to be picked up is kept. The mutual alignment between the
pick-up forks 14 and the slideways 17 of rack 4 is adjusted a-t the last
moment by means of an analogical position detec-tor 18. Preferably, the
uprights of rack 4 are provided with coded reference marks 19 so that
the analogical position detector 18 can add more precision to the posi-
tioning of the pick-up forks 14 by modifying on the one hand the level
of the pick-up means 9 carried by the post 15 and on the other hand the
position of the truck proper 6.
The extractor 16 comprises a motorized carriage 20 movable longi-
tudinally along the pick-up forks 14. Moreover, the extractor 16 comprises
means 21 for detachably anchoring said extractor to the basket, hopper or
dispenser in which the articles are stored.
In the case contemplated herein, the anchoring means 21 consist
simply of an electromagnet adapted to attract a metal member 22 secured
to the front side of each basket, hopper or dispenser 1.
Thus, the extractor 16 is firstly moved along the forks 14 until
the electromagnet 21 is relatively close to the metal member 22. ~hen the
electromagnet 21 is energized and thus caused to engage the metal m~mber
22 rigid with basket 1, rrhe extractor 16 is subsequently moved in the op-
posite direction along -the forks 14 and carries along the basket 1 which
will thus engage the slideways of pick-up forks 14.
_ 9 _
In order to ascertain that the selected article corresponds exact-
ly to the desired reference, there is provided according to this invention
on the front side of the baskets for storing the articles a coded label
23 with the reference number or symbol of the product contained in the
basket. A reader 24 for example of the laser type, carried by the truck,
will read the coded reference number or symbol of label 23 preliminary to
the picking up of the article in order to warrant the exac-tness of the o-
peration.
On the other hand, it is also possible to provide the pick-up means
with a device for assisting and controlling the picking up step. Thus, for
example, an optical device may be used for locating the position of the
articles in the basket for assisting the handling unit to be described
presently, this handling unit being designed for picking up said articles.
Preferably, the pick-up forks are mounted on a turn-table 25. This
possibility of rotating the pick-up forks 14 permits their alignment on
either side of the truck 6 and also their movement towards the embarked
store 10.
Preferably, this embarked store 10 is in the form of a swivelling
cabinet comprising several stacks of superposed modular racks disposed at
spaced intervals around the cabinet 10.
Thus, by way of example, Figure 6 illustra~es four stacks adapted
to receive storage baskets or order-regrouping baskets.
Due to its rotational mounting, the swivelling cabinet is adapted
to direct one of the stacks towards vertically movable pick-up means per-
mitting of extracting the basket contained in the swivelling cabinet for
restocking purposes or delivering thereto an article picked up by the
handling system, said basket being subsequently re-introduced into the
swivelling cabinet which therefore operates as a means for regrouping the
articles corresponding to predetermined orders.
The handling system 11 comprises a pick-up head 26 of the type
shown in Flgure 10, mounted on a carriage 27 movable along a horizontal
rod 28 secured to the post 15. This rod 28 is adapted to slide along the
post 15 and connected through means 29 for example as shown diagrammati-
cally in Figure 5 to the turn-table assembly 25 supporting the pick-up
forks 14 so as to preserve a relative constant position with respect to
the pick-up means.
On the other hand, the pick-up head 26 comprises a vertically mo-
vable support arm 30 permitting the downward movement of this head into
the baskets supported by the pick-up forks 14 for picking up an article
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contained in this basket.
Considering the wide variety of articles likely to be kept inthe warehouse, the pick-up head may comprise various gripping tools adapt-
ed to be actuated selectively according to requirements. In the example
shown in Figure 9 the gripping tools comprise a small sucker-cup 31, a
large sucker-cup 32 and wheels 33 of which the mode of operation will be
described presently. The principle of operation of sucker-cups 31 and 32
is well known per se. In short, a vacuum is created therein to that the
article adheres to the cup. Possibly, the sucker-cup 32 for example may
be provided with means for rotating it through an angle of 90 to permit
the storage of the article or object thus picked up.
The vacuum created in the operative sucker-cup is obtained by means
of a turbine 37 (Figure 10) connected to the three-armed spider 35 compris-
ing for this purpose hollow arms and a distributor associated therewith
for connecting the hollow arm 34 of the selected or operative sucker-cup
to the turbine.
l'he twin-wheels 33 are specially designed for engagement with
flexible or soft objects loosely contained in the storage hoppers 2. In
fact, it is particularly difficult to pick up a single flexible article
loosely disposed in a hopper, such as textile articles.
The principle of operation of wheels 33 is illustrated in Figures
11a and 11b.
Preferably, the wheels 33 have a conical configuration; however,
a cylindrical shape may also be contemplated. The wheels 33 are power
driven and kept in mutual contact through their common generatrices.
In operation, the wheels 33 are lowered into the hopper 2 as il-
lustrated in Figure 11a until they engage the articles 38 loosely dis-
posed in the hopper 2.
Then, the wheels 33 are caused to rotate in opposite directions
so as to grip the thus engaged flexible article.
A device is provided for detecting the presence of the article
between the wheels 33. A device responsible to the gap existing between
the wheels 33 as a consequence of the introduction of an article there-
between may be provided.
When the article is snapped up the rotary motlon of wheels 33 is
stopped and the gripping tool can be raised as shown in Figure 11b, the
article being pulled upwards between the wheels 33.
To release the article 38 from the wheels, it is only necessary
to reverse the direction of rotation of wheels 33. Preferably, a hopper
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2 is used for storing loose articles so that they gather by gravity in the
bottom of the hopper, irrespective of their number or a unt. Under these
conditions, the articles can be picked up separately with great facility
irrespective of the n~ber of articles remaining in the hopper.
Consequently, the above-described movable carriage is applicable
to the picking up of multifarious articles from stocks in order tQ gather
the articles thus picked up in pick-up baskets kept in the embarked store
10, said pick-up baskets being subsequently delivered to the dispatching
department or station where the articles are packed and dispatched.
The self-propelled truck described hereinabove may also be used
for restocking warehouses.In this case, the handling system 11 is not
used.
In case the orders relate to a single article, one may advanta-
geously use the self-propelled truck illustrated in Figures 12 and 13. In
this case, the self-propelled truck 6 comprises pick-up means 9 similar
to those described with reference to the preceding form of embodiment
which comprises extraction forks 14 mounted on a vertical post 15 and a
handling system 11 adapted to pick up an article contained in a basket
supported by the extraction forks 14.
However, the embarked store 10 comprises a bagging device 12, In
the example of Figures 12 and 13 the self-propelled truck comprises a con-
veyor 39 adapted to be loaded with the goods to be packed. This conveyor
39 drops the article or articles into a spout 40. The bottom of this spout
40 consists of a bag 41 preformed from a plastic film 42 paid off a supply
roll. This plastic film 42 may consist for example of a polyethylene film
adapted to be welded on the machine. The selected article falls into the
bag 41 which is then sealed, suitable means 43 being provided for subse-
quently applying a label to this bag, this label displaying for example
the reference numbers and signs of the customer's order as well as the
consignee's address.
The bag is cut and directed toward a storage basket in the form
of a small wheeled box 44. In the example illustrated in Figures 12 and
13 four boxcs 44 are provided. Cutting the bag permits of forming the
bottom of the next bag and thus the bag for the next article is pre-shaped
automatically. If desired, the self-propelled truck 6 of the present in-
vention may be provided with a handling system 45 for dispensing advertis-
ing articles or gifts. In this case, the truck 6 is provided with a dis-
penser 46 containing all the gifts 47 to be dispatched with each order.
The handling system 45 will pick up automatically a gift 47 in the dispen-
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ser and this gift 47 will be released on conveyor 39 so that each article
picked up by the pick-up means 9 and handling system 11 is accompanied by
a gift introduced into the spout 40 simultaneously with the ordered arti
cle.
A sorting mechanism 48 may advantageously be disposed at the out~
put end of the bagging device 12 for directing the bags towards one of the
wheeled boxes 44 so as to meet predetermined requirements.
Thus, according to the specific nature of the operations perform-
ed, the self-propelled truck of this invention may be provided with one
or more of the various equipments described hereinaboveO
Figure 14 illustrates in plane view a robot goods-handling ware-
house adapted to be equipped with self-propelled trucks according to the
present invention. Of course, this arrangement is given by way of example,
not of limitation.
The warehouse comprises a relatively large number of storage racks
4 filled with baskets/ hoppers or dispensers. Preferably, the warehouse
is divided into several sections, departments, stations or areas; in the
example illustrated, it is divided into four sections I, II, III, IV
corresponding each to an article of specific or different nature, notably
relatively cumbersome articles in the 'upstream' sections and small, loose
articles in the remaining sections.
~ he path followed by the self-propelled trucks for collecting the
elements or articles relating to a specific order is made of successive
imbricated loops. In the example shown in Figure 14, the incoming and empty
self-propelled trucks from the dispatching station travel in the direction
of the arrow 49 and engage lane 50 for picking up any article or articles
stored therein, then penetrate into lane 51 in the opposite direction and
through lane 52, before returning through lane 53, so that the truck has
run through the entire section I. Sections II, III and IV are also covered
in the same manner. However, it is unnecessary to cause the truck to run
through all the lanes iE no article is to be picked up in a there and back
run.
At the end of section IV, the self-propelled trucks follow the
track 54 leading to the packing station.
Preferahly, the lanes are wide enough to enable one truck to over-
take another truck. This possibility will improve considerably the rate
of operation and cannot cause any undesired holdup in the system, even in
case of truck failure.
Restocking is made possible by -the provision of special auxiliary
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racks 55. These racks 55 are particular in that the baskets or like con~
tainers disposed therein can be extracted from one or the other side of
the rack. ~hus, the operators 56 disposed behind the racks will firstly
remove the empty baskets from the rack in order to fill them with articles
brought from the main general store, and then re-introduce the filled bas-
kets into the racks. Special restocking self-propelled trucks will be dri-
ven along the aux.iliary racks 55 in lanes 57 for bringing empty baskets
and pick up the filled baskets for restocking the racks 4. However, arti-
cles can be picked up by the self-propelled pick-up trucks from racks 55
by driving the trucks along lanes 57, that is, without interfering with
the picking up of reference articles during the restocking thereof.
In the example described hereinabove, the simultaneous operation
of self-propelled trucks for picking up articles from the stock, and of
other trucks for restocking the warehouse, is contemplated. ~lowever, in
slack business periods it is possible to use only a single truck operat-
ing at times for restocking and at other times for collecting articles
according to a given order.
Of course, other modes of operation will readily occur to those
conversant with the art without departing from the basic principles of
the invention.
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