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BACKGROUND OF THE INVENT
1. FIELD OF THE INVENTION
This invention relates generally to inventory systems, and more
specifically to a method for locating and retrieving a randomly placed
object.
2. DESCRIPTION OF THE PRIOR ART
The use of automated inventory and retrieval systems has become a necessity
for many large-volume processes in which a large number of items must be
stored for a period of time. Such processes include assembly line
operations wherein a large number of identical items are temporarily
stored prior to subsequent non-identical processing as well as retrieval
systems where a large number of unique items must be stored in a manner
such that quick retrieval is allowed.
In the prior art, an apparatus and method for positioning a vehicle at a
storage bin in an automated storage and retrieval system is disclosed in
U.S. Pat. No. 4,415,975, Burt. A retrieval vehicle is positioned at a
storage bin in a three-dimensional rack structure containing objects in
discrete storage bins of the rack structure. The method described by Burt
allows precise positioning of the retrieval vehicle given an already known
location of the stored object. This known method, however, requires a
rigid rack structure, and presupposes that the location of the stored
object in the rack structure is already known. Frequently, however,
storage areas do not contain rack structures nor are the storage locations
of the objects already known so as to allow positioning of a retrieval
vehicle. For example, in steel finishing facilities, steel coils are
temporarily stored in a random manner in production or storage bays in any
available space.
In the manufacture of various alloy products, such as stainless steel
sheets or silicon steel sheets, the product at several intermediate stages
of production and the final product is in the form of a coil. These coils
are placed in holding areas next to the production units and/or, when
space permits in-storage bays prior to further processing or, after
processing is completed, prior to shipment to a customer. To move the
coils, use is often made of an overhead crane. The overhead crane embodies
a crane bridge that moves through the bay warehouse along parallel tracks
thereby providing movement back and forth in one direction. The crane
further embodies a crane trolley that moves horizontally along the crane
bridge in a direction of travel perpendicular to that of the crane bridge,
thereby providing movement back and forth in a second direction. The crane
bridge and trolley allow the overhead crane to be positioned above any
area in which coils can be placed. The trolley has a reel that allows
raising and lowering of an object fastener such as a hook or a magnet, for
example. The object fastener is connected to the trolley by a cable and
the object fastener is raised and lowered by winding and unwinding hhe
cable connected to the reel of the trolley.
In conventional practice, coils are placed in rows, and, in some storage
areas, a second and even third layer of coils are stacked vertically. Each
coil is identified by a tag affixed thereto, or by markings directly on
the coil. Unfinished coils may be selected for further processing in a
specific order on the basis of the requirements of the next process. For
example, different coils may be selected so that the width of strip in a
rolling mill progressively decreases between successive coils, or to allow
progressive increase of the acidity of a liquid in tubs of a pickling
line.
In conventional practice, a particular coil is located by a person, called
a stocker, who moves on foot through the storage area and manually locates
each of the required coils. When the coil has been located in this manner,
the person then signals a crane operator to position the crane above the
coil. If the crane is not available to pick up the coil, the coil is
marked on the top thereof for identification and later retrieval by the
crane operator. This is a cumbersome, unsafe, and time-consuming
operation. Consequently, the production schedule for further processing of
coils frequently cannot be maintained because the coils cannot be located
and retrieved in an expeditious manner.
It is accordingly a primary object of the present invention to provide a
method for locating and retrieving randomly placed objects without
requiring manual discovery of their location.
A further, more specific object of the invention is to provide a method for
locating coils so that a coil can be picked up by an overhead crane
wherein the crane bridge, trolley, and object fastener may be moved to the
proper position for pickup of the desired coil without manually locating
the coil and subsequent signalling to the crane operator with respect to
the location of the coil.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a method for
locating and retrieving a randomly placed object. The method includes the
steps of interrogating a previously created data base by entering the
indicia of identification. The software returns the X, Y, Z location of
the object. These coordinates can then be supplied to the retrieval
vehicle operator. The method includes building the data base by the prior
steps of attaching an indicia of identification to each object to be
randomly placed, recording the indicia of identification and determining
the coordinates of the location of the object at the time of placement and
indexing the coordinates of the object to the indicia of identification.
When recovering an object, the additional steps include determining
coordinates for the location of a transporting means, comparing the
coordinates of the transporting means with the coordinates of the object,
and moving the transporting means to the coordinates of the object.
The indicia of identification attached to the object may be a visual
indicia and such indicia can be recorded by a camera mounted on the
transporting means. Recording and indexing the indicia of identification
and the coordinates of location of the object may further be carried out
in a computer, while the transporting means may include a land vehicle
such as a ram truck or an overhead crane, bridge, trolley and object
fastener.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be better understood and further advantages and uses
thereof more readily apparent when considered in view of the following
detailed description of exemplary embodiments taken with the accompanying
drawings in which:
FIG. 1 is a block diagram of one form of apparatus to practice the method
of the present invention for locating and retrieving a randomly placed
object;
FIG. 2 is an isometric illustration of an overhead crane operative above
steel coils in a storage area;
FIG. 3 is an elevational view of a further embodiment of apparatus to carry
out the present invention as applied to a storage area containing steel
coils; and
FIG. 4 is a schematic of a further embodiment of apparatus to carry out the
method of the present invention in a storage area containing steel coils
wherein the indexed coordinates of location of the steel coils are
telemetered to a remote computer.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to FIG. 1, there is shown a block diagram of an apparatus to
practice the method of the present invention. In its broadest form, the
method consists of identifying an object, placing it at any available open
spot, recording the identification, determining the location of the object
and creating an index with the object's identification indexed to the
location of the object. An identification means 8 allows a determination
of the identity of an object. The object identity, as determined by the
identification means 8, is inputted by line 10 to a recording means 12.
Also inputted to the recording means 12 is the location of the identified
object. The location of the object may be expressed as coordinates of a
coordinate system, such as coordinates X, Y, and Z of a Cartesian
coordinate system. These coordinates are recorded by the recording means
12 through lines 14, 16, and 18 indicating the X, Y, and Z coordinates of
the object, respectively. After recording, the coordinates of the object
and the identification of the object are correlated by an indexing means
20. Both recording and indexing may, for example, be accomplished by a
computer, identified by reference numeral 22 and encompassing both the
recording means 12 and the indexing means 20. The computer 22 allows
recording of data in a computer data base and indexing by simple software
manipulation. The indexed information of the coordinates of the location
of the object may be accessed at a later point in time, thereby allowing
quick retrieval of the object. Retrieval of the object may be accomplished
by retrieval means 24 which may be any of many types of retrieval devices.
While the apparatus shown by FIG. 1 is useful in many different
applications, described henceforth is a specific application of the method
as applied to a storage bay containing steel coils. The steel coils are
randomly stored in the bay awaiting further processing or shipment to a
customer.
Shown in FIG. 2 is an overhead crane 26 situated above steel coils 28 in a
storage area. The overhead crane 26 is movable in both the X and Y
direction of the coordinate system 30 to allow positioning above any
location in the storage area. The crane 26 comprises a crane bridge 31
containing girders 32 and 34 upon which tracks 36 and 38 are mounted,
respectively. A crane trolley 40 is supported on the tracks 36 and 38 by
wheels 42, thereby allowing movement back and forth across the bay in the
Y direction. At the extreme ends (one end shown) of the crane bridge 31
are wheels 43 supported by rails 44 running in a direction perpendicular
to the length of the crane bridge 31 allowing the crane 26 to be moved
back and forth along the bay in the X direction.
The trolley 40 is provided in a conventional manner with a winch for
winding and unwinding of cables 45 to which an object fastener 46, such as
a hook, is connected. The object fastener 46 connects to a "C" hook 48 to
allow lifting of a steel coil 28. Attached to each steel coil 28 is a tag
49 whose markings constitute the indicia identification of a particular
coil.
In operation, when a coil 28 is to be picked up by the crane 26, the bridge
31 moves along the rails 44 and the trolley 40 is then moved along tracks
36 and 38 of the bridge 31 to a position above the coil 28, whereupon the
"C" hook 48 is lowered by cable 45 for connection to the coil 28.
Referring now to FIG. 3, there is shown schematically an embodiment of the
present invention applied to the above-described warehouse which allows
location and retrieval of a steel coil 28 randomly placed by an overhead
crane in a storage area. The overhead crane 26 is shown in elevation, with
the Y direction of the coordinate system perpendicular to the plane of the
illustration. The crane bridge 31 may be moved back and forth in the X
direction, which is from left to right and vice-versa as one views FIG. 3.
Also shown in FIG. 3 is a video camera of a vision system 50 connected to
the crane trolley 40. The video camera 50 functions to record the indicia
of identification of the steel coil 28. This indicia of identification is
placed in a position readable by the camera 50 by means of tag 49, for
example.
Various specific practices may be used to identify the steel coil 28 as
well as the position of the overhead crane 26. For example, the identity
of the coil 28 may be determined at the time of placement by the vision
systems. By recording the digitized location of the overhead crane 26, in
terms of the position of the crane bridge 31 (the X coordinate), the
position of the crane trolley 40 (the Y coordinate), and the position of
the hook 48 (the Z coordinate), at the instant in time when the steel coil
28 is placed in its storage position, the digitized information of the
coordinate at this instant in time of the overhead crane 26 may be
recorded in a computer data base and indexed by computer software to the
identity indicia, thereby providing an indexed record of the identity and
of the position of the steel coil 28.
If the steel coil 28 is picked up and moved to another location in the
storage warehouse, the new position of coil at the time of placement is
recorded in the computer data base. The indicia of identification on the
tag 49 is first recorded by the camera 50, and the coordinates for the
bridge 31, trolley 40, and hook 48 of the crane 26 are determined,
recorded, and indexed to the indicia of identification of the tag 49
located on the coil so that the location of the steel coil 28 may be
updated. In this manner, determination of the crane position and the
indexing thereto to the indicia of identification of the steel coil 28 is
maintained on a continual basis.
The crane 26 may be operated either manually to position it at a desired
location or, alternatively, automatically in response to a computer
output.
In the simplest embodiment of the invention, a crane operator uses a
keyboard to input into a computer 52 the indicia of identification located
on the tag 49 of steel coil 28 after viewing the picture from the video
camera 50. The operator also enters into the computer 52 a visual estimate
of the location of the overhead crane 26 when the steel coil 28 is placed
in its storage position. A referenced location is thereby established
which can be used later to locate and retrieve the coil 28. The operator
can then operate a retrieval device such as a vehicle or crane for
movement of the retrieval device to the retrieval location.
In a more sophisticated embodiment, a display in the crane cab of the X, Y,
and Z coordinates of the crane position is available at all times,
allowing the crane operator to input the coordinates by a keyboard into
the computer 52 each time a coil 28 is placed in a storage location.
Further, this input may be entered into the computer 52 automatically by
electronic means rather than manually by the crane operator. The video
camera 50 may further include a microprocessor with character recognition
software, thereby avoiding all manual entry by the crane operator. With
such electronic inputs to the computer 52, the only additional duties of
the crane operator are to position the coil 28 to ensure that during
storage the tag 49 is always in the field of view of the camera 50, and to
initiate recording of the location of the coil 28. By simply pushing a
"PLACE" button, at the instant in time when the coil 28 is placed in its
storage location, the identity and location of the coil 28 may be inputted
to the computer 52.
Although various equipment is commercially available for use to practice
the present invention, the following is a description of specific
apparatus suitable for use. A vision system to "see and read" the indicia
of identification, such as a tag, on the object to be located, picked up,
or otherwise retrieved, may be a reading system, per se, is well known in
the optical character reading art. This vision system "sees" and displays
on a screen the indicia of identification and also outputs the indicia of
identification in computer readable form. The indicia may be stored in any
conventional microcomputer which may be located directly in the crane cab.
In an embodiment in which an overhead crane 26 is the retrieval means, a
rotatable, preferably a non-driven wheel on the crane bridge 31 and a
rotatable, preferably a non-driven wheel on the trolley 40 may be coupled
to pulse generators 54 and 56, respectively, which delivers pulsed outputs
to a microcomputer corresponding to the rotary motion of the wheels
according to the location of the bridge 31 and trolley 40. To record the
vertical (Z) coordinate in a storage area in which coils are stacked upon
one another, the crane operator may be given a series of numbered "PLACE"
buttons. When the crane 26 is stopped to place a coil 28, the crane
operator pushes a first "PLACE" button if the coil is placed on the floor,
a second "PLACE" button if the coil is placed in a second layer, and etc.
Thus, the vertical location Z has a unique value of 1, 2, etc., depending
on the practice in that storage area. When the button is pushed, the
microcomputer records which button is pushed, and retains the X and Y
values existing at that instant along with the identity of the coil 28.
In the fullest embodiment, the indexed information of the identity and
location of the coil 28 is telemetered from the computer 52 to a ground
base receiver. As shown in the schematic of FIG. 4, the computer 52 is
inputted information concerning the identity of the coil 28 from the
camera 50, and the coordinates of the position of the crane 26 from the
pulse generators 54 and 56. Transmitting means connected to the computer
52 is transmitted to the ground receiver 58. The ground receiver 58
transfers the indexed information to a plant inventory and scheduling
oomputer 60 and the information then becomes resident in the data base of
the computer. A terminal 62 for the plant inventory and scheduling
computer is operative to determine the most expeditious sequencing of coil
handling for further processing, and allows quick determination of the
location of the entire inventory of coils in the storage areas. By
inputting the indicia for coils to be retrieved their location can be
given to the operator of the storage vehicle by hand list or by reverse
transmission to be displayed on the vehicle operator's CRT.
While the present invention has been described in connection with the
preferred embodiment shown in FIG. 3, it is understood that other similar
embodiments may be used or modifications and additions may be made to the
described embodiment for performing the same functions of the present
invention without deviating therefrom. For example, many storage
warehouses use ram trucks as opposed to overhead cranes to move the steel
coils. It is to be noted, thus, that the teachings of the method of the
present invention are applicable to the system regardless as to the exact
means of transportation used to move the steel coils. Furthermore, the
objects to be moved need not be steel coils, but may be virtually any bulk
object sought to be identified and retrieved in any random warehouse.
Therefore, the present invention should not be limited to any single
embodiment but rather construed in breath and scope in accordance with the
recitation of the appended claims.
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