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BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates in general to improvements in computer based
manufacturing systems and in particular to improvements in determining
optimal routes for moving materials between workstations in a computer
based manufacturing system. Still more particularly, the present invention
relates to a method and system for automatically determining an optimal
route among many available routes for transporting materials between
workstations within a computer based manufacturing system.
2. Description of the Related Art
Computer based manufacturing systems are well known in the art. The process
of designing, developing and manufacturing a new product, or making major
changes to existing products, presents many challenges to product managers
and manufacturing managers. It is important to maintain product quality
while bringing a product to market for the least cost, within a set
schedule. In today's highly competitive industries, product managers and
manufacturing managers require information to address many problems which
arise because of the complexity of new products and the complexity of
world-wide production and the changing nature of competition. A
requirement that products be manufactured for the least possible cost is
an important requirement in all industries.
Many texts have been written concerning the field of production management.
For example, Joseph Orlicky wrote Material Requirement Planning, published
by McGraw-Hill, which has become the industry standard reference for
almost all job shop planning requirements. This concept of planning and
releasing work to the manufacturing shop floor is well accepted and, even
today, many vendors are selling software based upon this concept. From a
dispatching point of view, this system takes into account only the general
concept of a first-in, first-out (FIFO) basis of dispatching. Dr. D. T.
Phillips and G. L. Hogg published a paper entitled A State-of-the-Art
Survey of Dispatching Rules for Manufacturing Shop Operations,
International Journal of Production Research, Volume 20, No. 1, pages
27-45, which provides varying dispatching rules which may be utilized in a
planning process.
International Business Machines Corporation has developed a product called
"Capacity Planning and Operation Sequencing System (CAPOSS)", described in
Education Guide No. SR19-5004-0, published by International Business
Machines Corporation, which provides static dispatching functions in the
form of deciding the next operation to be performed for an order after
completion of a prior operation.
One important feature in modern day manufacturing facilities is the need
for an improved parts and materials supply system which is necessary to
minimize inventory and floor space required for parts storage at the
workstations. The efficiency and economy of so-called "just in time"
inventory control systems is now well recognized and many systems have
been implemented which attempt to impose such a delivery system. For
example, U.S. Pat. No. 4,669,047 discloses an automated parts supply
system which may be utilized to implement a "just-in-time" supply system.
U.S. Pat. No. 4,472,783 describes an improved flexible manufacturing system
which utilizes multiple numerically controlled machine tools. In
accordance with a supervisory control computer the system described
therein supplies routing information to the material handling system
controller which in response, controls the movement of pallets through a
manufacturing production path to various machine tools. This system deals
with a novel method of controlling a specific type of manufacturing line.
Similarly, U.S. Pat. No. 4,561,060 describes a system for controlling the
flow of articles within a work area which includes multiple workstations
and for acquiring real time information relating to the status of the work
in progress.
None of the above described methods disclose a means for determining the
best method, among available alternatives, for transporting materials and
product between work centers, while considering various factors such as
fragility, size or weight. Modern systems have become so complex that it
is not uncommon for multiple modes of material movement to be available
for transferring product between locations within and among manufacturing
work centers and the availability of such multiple modes of transportation
has substantially increased the complexity of the tasks of determining an
optimal path for product to be transported within a computer based
manufacturing system. Further, a manufacturing process may be distributed
over a wide geographic area, requiring a much more sophisticated level of
control for transport of product throughout the process. It is therefore
obvious that a need exists for a method and system which may be utilized
to optimize the movement of material within a manufacturing process within
a dynamic, changing environment.
SUMMARY OF THE INVENTION
It is therefore one object of the present invention to provide an improved
computer based manufacturing system.
It is another object of the present invention to provide a method and
system for determining optimal routes for moving materials between
workstations within a computer based manufacturing system.
It is yet another object of the present invention to provide an improved
method and system for determining an optimal route among many available
routes for transporting material between workstations within a computer
based manufacturing system which is suitable for automatic processing.
The foregoing objects are achieved as is now described. A method and system
for determining an optimal material movement product path within a
computer based manufacturing system is disclosed. A transport matrix is
created having multiple rows and columns, each associated with a
workstation within a computer based manufacturing system. At each cell
within the matrix located at an intersection of a selected row and column,
the attributes for all possible methods of transport between the
associated workstations are listed. Preferably transport attributes, such
as transport type, velocity/distance, travel time, capacity, authorization
required, fragility, cost and current status of the transport system are
listed within the cell and may thereafter be dynamically updated. After
identifying a selected product path an analysis of the transport matrix
may be utilized to determine an optimal route based upon user inputs, such
as the most rapid, least expensive, or most reliable form of transport,
for transporting material between selected workstations.
BRIEF DESCRIPTION OF THE DRAWING
The novel features believed characteristic of the invention are set forth
in the appended claims. The invention itself however, as well as a
preferred mode of use, further objects and advantages thereof, will best
be understood by reference to the following detailed description of an
illustrative embodiment when read in conjunction with the accompanying
drawings, wherein:
FIG. 1 is a schematic view of a plurality of workstations within a computer
based manufacturing system;
FIG. 2 is a pictorial representation of a computer display screen depicting
a transport matrix created in accordance with the method and system of the
present invention;
FIG. 3 is a pictorial representation of the computer display screen of FIG.
2 including an additional display of transport attributes;
FIG. 4 is an enlarged pictorial representation of one embodiment of a
workstation row or column within the transport matrix of FIG. 2;
FIG. 5 is an enlarged pictorial representation of one embodiment of a
transport method cell within the transport matrix of FIG. 2;
FIG. 6 is a high level flowchart depicting the creation of the transport
matrix of FIG. 2; and
FIG. 7 is a high level flowchart depicting an analysis of an optimum
product path utilizing the transport matrix of FIG. 2.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
With reference now to the figures and in particular with reference to FIG.
1, there is depicted a schematic view of a plurality of workstations
within a computer based manufacturing system 10. As illustrated, computer
based manufacturing system 10 includes a plurality of workstations 16, 18,
20, 22, 24, 26 and 28. As those skilled in the art will appreciate, each
workstation depicted represents a location wherein an operation upon
material will occur or materials may be stored during the manufacturing
process. Of course, each workstation may represent a location within a
different country, multiple locations within a single country, multiple
locations among buildings at a single manufacturing site or multiple
locations among work cells or work areas within a single building.
Connecting each of the workstations depicted are various transport methods
30 which are depicted schematically utilizing arrows connecting individual
workstations.
Transport methods 30 represented schematically within FIG. 1 may represent
multiple types of transport such as a conveyor belt systems, carts,
trucking routes, air transport routes, or other various types of
transportation. Additionally, those skilled in the art will appreciate
that while a single transport method 30 may be depicted within FIG. 1 for
connecting a selected workstation to a second selected workstation in
reality multiple methods of transport may be available to relocate a
product from one workstation to a second workstation.
Also depicted within FIG. 1 is a computer 12. Computer 12 is preferably
utilized to schedule and control operations within the computer based
manufacturing system depicted and, may be implemented utilizing any
suitable computer, such as the International Business Machines Corporation
AS/400. A display screen 40 is depicted within computer 12 and may be
utilized, in accordance with the method and system of the present
invention, to display and depict a transport matrix which may be created
in accordance with the teachings contained herein. Additionally, a
graphical pointing device 14 is associated with computer 12 in a manner
well known to those skilled in the computer art and may be utilized, as
will be explained in greater detail herein, to manipulate data within a
transport matrix.
Referring now to FIG. 2, there is depicted a pictorial representation of a
computer display screen illustrating a transport matrix 40, which is
created in accordance with the method and system of the present invention.
As is illustrated, transport matrix 40 includes a plurality of rows and
columns, each of which is associated with a selected workstation within
computer based manufacturing system 10 (see FIG. 1). Thus, row 42 is
associated with workstation 1, row 44 is associated with workstation 2,
row 46 is associated with workstation 3 and row 48 is associated with
workstation N. Similarly, each column within transport matrix 40 is also
associated with a workstation within computer based manufacturing system
10. That is, columns 50, 52, 54, and 56 are associated respectively with
workstations 1, 2, 3 and N.
Of course, those skilled in the art will appreciate that transport matrix
40 may be created in whatever size is necessary to accommodate each
workstation within computer based manufacturing system 10. Thereafter, in
accordance with an important feature of the present invention, each cell
within transport matrix 40 has associated therewith a listing of methods
of transport and associated attributes for those methods of transport
which are available to transport material from a workstation associated
with a particular row to a workstation associated with a particular
column. 0f course, since transport between a workstation and itself will
not be necessary, the diagonal of transport matrix 40 will be left blank,
or may be utilized for local movement within a workstation, e.g.
input/output buffers.
In the depicted embodiment of FIG. 2, a graphic illustration of each type
of transport is illustrated. That is, a graphic depiction of a conveyor
belt, transport cart, truck or airplane may be utilized to indicate the
method of transport which is available to transport material from one
workstation to another workstation, as illustrated at various cells 60
within transport matrix 40. Additionally, in the event multiple methods of
transport exist for transporting material from a particular workstation to
a second workstation, transport matrix 40 may be three-dimensional in
nature or, alternatively, a graphic indication of alternate methods of
transport may be included within each cell 60, in a manner which will be
explained in greater detail herein. Also depicted within FIG. 2 is mouse
pointer 64, which may be utilized in the so-called "point and click"
method to select a particular method of transport and thereafter display
the attributes associated with that method of transport, in a manner which
will be depicted in greater detail below.
With reference now to FIG. 3, there is depicted a pictorial representation
of the computer display screen of FIG. 2, including an additional display
of transport attributes. As illustrated, transport matrix 40 of FIG. 2 is
depicted and a particular cell 60 at the intersection of row 42 and column
52, has been selected, preferably utilizing a graphical selecting device,
such as mouse pointer 64. In response to such selection a transport
attribute viewport 66 is displayed which includes a plurality of
attributes associated with the particular method of transport depicted
within cell 60. In the depicted embodiment of the present invention,
attributes such as the type of transport, velocity/distance or travel
time, capacity, authorization required, fragility, cost and current status
of the type of transport are displayed. Additionally, a second transport
attribute viewport 68 may be displayed in an overlapped manner, such as
that depicted within FIG. 3, indicating the existence of an alternate
method of transport between workstation 1 and workstation 2.
Referring now to FIG. 4, there is depicted an enlarged pictorial
representation of one embodiment of a workstation row or column within the
computer display screen of FIG. 2. As illustrated, in this depicted
embodiment of the present invention, row 42 which is associated with
workstation 1, includes a graphic illustration 70 which may be utilized to
depict in iconic form an identification of the type and/or purpose of
workstation 1. Iconic representation 70 is preferably utilized to indicate
that workstation 1 is a stamping workstation wherein material may be
modified utilizing a stamping or die cutting type machine.
With reference now to FIG. 5, there is depicted a transport method cell 60
within the computer display screen of FIG. 2, which includes an iconic
representation 72 which may be utilized to identify the method of
transport which is illustrated within cell 60. Iconic representation 72
depicts a truck, indicating that transport of material from the
workstation associated with the associated row to the workstation
associated with the column associated with cell 60 is by truck transport.
Additionally, alternate transport selection blocks 74, 76, 78 and 80 may
be utilized to graphically indicate the presence of additional methods of
transport between the workstations associated with this cell.
Referring now to FIG. 6, there is depicted a high level flowchart depicting
the creation of transport matrix 40 of FIG. 2. As illustrated, the process
begins at block 90 and thereafter passes to block 92 which depicts an
identification of all workstations within a selected computer based
manufacturing system. Next, the process passes to block 94 which depicts
the creation of a transport matrix in the manner depicted within FIG. 2.
Thereafter, all available methods of transport between the various
workstations located within the transport matrix are identified, as
illustrated in block 96, and block 98 then depicts the filling of the
cells within the transport matrix with transport method attributes.
Thereafter, the process terminates, as illustrated at block 100.
Finally, with reference to FIG. 7, there is depicted a high level flowchart
depicting an analysis of an optimum product path utilizing the transport
matrix of FIG. 2. As above, the process begins at block 110 and thereafter
passes to block 112, which illustrates the identification of a desired
product path. Those skilled in the computer based manufacturing arts will
appreciate that scheduling of a particular product path may be
accomplished by identifying those workstations which must necessarily
operate upon a material to create the desired product. Additionally,
multiple methods of transport may exist for moving material from each
workstation within the desired product path to a subsequent workstation.
Therefore, block 114 illustrates the prompting of a user for desired path
attributes. These attributes may be selected by a user in order to
minimize or maximize any objective function. For example, the fastest
available method may be selected. Alternately, the least expensive method
or shortest route may be selected by the user for a desired path
attribute. Similarly, the desired path attributes may be arbitrarily
complex. For example, a user may require the optimum path to be specified
as that route which is least expensive which; however, has a ninety
percent probability of completion within a specified period of time.
Similarly, a user may specify a path which will complete production at the
earliest possible moment including considerations of availability,
reliability, and speed. Of course, those skilled in the art will
appreciate that the term "user" as utilized herein, may mean a dispatch or
shipping program, in addition to an actual human operator of the system.
In situations wherein the "user" is a shipping program or the like, the
method and system and system of the present invention may be processed
automatically.
After prompting the user for the desired path attributes for an identified
product path block 116 depicts the analysis of the transport matrix, which
was created within FIG. 6. This may be accomplished utilizing any well
known matrix/path analysis technique. Block 118 then illustrates the
specification of the optimum product path complying with the user's
desired path attributes and the process then terminates, as depicted at
block 120.
Upon reference to the foregoing those skilled in the art will appreciate
that the Applicants herein have provided a method and system for
describing alternate modes of material movement between locations within a
computer based manufacturing system and for the efficient utilization of
this information in creating an optimum routing for material within that
system. The information regarding alternate modes of material movement, as
well as particular information relating to each of these alternate modes
may be dynamically updated to compensate for variations in the transport
modes available while still providing an optimized route for material
movement within the system.
While the invention has been particularly shown and described with
reference to a preferred embodiment, it will be understood by those
skilled in the art that various changes in form and detail may be made
therein without departing from the spirit and scope of the invention.
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