Production plan generating method and apparatus

A production plan generating apparatus, and a method, are provided for generating production plans in sequential chronological order, from an ultimate downstream process in which a final product is produced, to all of the upstream processes required to produce components needed to make the final product. The apparatus includes an input device for inputting initial data including ultimate downstream process data, and a memory for storing the input data, machine data and process data, and a generator for generating a production plan for the final product, and upstream plans for the components and/or sub-components which are required in order to produce the final product. The generator uses the ultimate downstream process data to generate intermediate downstream process data relating to the production process that occurs just before the ultimate downstream process is effected, and sequentially generates data relating to further upstream processes in a sequential order, using data from an immediately prior upstream process plan.

BACKGROUND OF THE INVENTION 
I. Field of the Invention 
The present invention generally relates to a production plan generating 
method and to a related apparatus for generating production plans in 
accordance with the method, and more particularly relates to a dynamic 
scheduler which is adapted for coordinating the production of one or more 
assembly lines making different finished products, each assembly line 
including a plurality of production steps. 
II. Description of Background Material 
As a result of advances in technology and rapidly changing consumption 
patterns, manufacturers must presently contend with a rapidly changing 
manufacturing environment which is often characterized by the manufacture 
of a wide range of goods in relatively small production lots, with such 
goods having shorter delivery schedules and shorter product life cycles 
than has previously been the case. The ability to respond quickly and 
sensitively to market changes is now extremely important in such a 
multi-product, small-lot manufacturing environment, and requires the 
ability to generate precise plans for factories which produce goods having 
multiple production processes or steps and/or which include several 
product lines, the ability to rapidly change these plans, and the ability 
to efficiently produce an appropriate number of components and finished 
products without unnecessary expenditure of material, time or cost. 
A number of attempts have been made to facilitate and/or computerize 
production processes for the manufacture of various products. 
One known production plan generator is illustrated in FIG. 6, which 
schematically illustrates a system which was disclosed, e.g., in Japanese 
Published Patent Application 62-52,666. In this known generator, a central 
processing unit (i.e., CPU) 101, typically a computer, is used to generate 
a production plan in accordance with a provided production plan generating 
program 100. A memory 102 for storing basic data relating to the 
production equipment to be used, and other parameters, is connected to 
enable access to such data by the CPU 101. An additional memory 103 is 
used as working memory by the CPU, such that the CPU can therefore 
generate a production plan based upon the stored data. 
Known data that is essential to each of the processes to be scheduled by 
this system can be entered through an input device 104, e.g., a keyboard, 
connected to CPU 101. A "plan results" memory 106 is provided for storing 
the production plan generated by the production plan generating program in 
the CPU, a display device 107 is provided for displaying the plan results, 
and a printer 108 is provided for printing the plan results, with the 
printer also being connected to CPU 101. 
In this prior art system, the noted production plan generation process is 
executed separately for each step in the production process, based upon 
the basic data which is input via input device 104, and upon data which is 
provided in working memory 103. Because the product plan generation 
process is executed separately for each production process step, when one 
or more processes or steps are interrelated, the personnel operating the 
planner for an "upstream process" (i.e., a process which is performed 
earlier during production of a final product) must cross reference or 
otherwise relate the proposed production plan for such an upstream process 
step with the proposed production plan for a downstream process step 
(i.e., a sequentially later process which is required to be performed in 
order to produce a finished product). It is necessary to do so in order 
that the personnel can identify any factors present in the "downstream 
process" that depend upon certain conditions, requirements, or factors 
relating to the "upstream process" (e.g., the volume of product required 
by the downstream process), and to thereafter input any such conditions as 
feedback to the production plan generator for the upstream process. The 
generator must then run again in order to generate a production plan for 
the upstream process that is compatible with the requirements of the 
downstream process. In other words, the operator of the system which is 
designed to produce a production plan generating program for an upstream 
process cannot operate in ignorance of the later, downstream processes 
which are required in an overall production plan, and in fact requires 
information from the later in time (during production of a given final 
product) downstream processes in order to be able to properly plan a given 
upstream process. As an example, an operator would have to know the volume 
of product which is going to be produced at a downstream process step, and 
the date by which they need to be produced, and the time when they are 
produced, in order to accurately execute a final production plan for an 
upstream process. 
In many factories, however, goods are manufactured through a series of 
plural production process steps. Thus, while the system described in FIG. 
6 constitutes a conventional planning process which optimizes the 
production plans of individual processes or steps used to produce final 
products, it involves developing production plans dependent upon each 
specific process, or a number of processes, or developing separate 
production plans for each process; and such a system does not interrelate 
all of the processes or steps, and therefore cannot optimize the 
production plan for an overall production process which involves a series 
of steps, processes and/or components to produce a final product. In order 
to overcome such a deficiency, personnel working with an upstream process 
must necessarily identify the needs-production data (e.g., final 
parameters representing the quantities of specific products which are 
required to be produced in subsequent steps) of a later, downstream 
process or step (e.g., the final downstream process or an intermediate 
downstream process), and thereafter determine any conditions that must be 
satisfied by the upstream process which the personnel is involved with as 
a result of the later implementation of any such downstream steps. 
Thereafter, the needs-production data must be entered into the upstream 
production plan, and such production plan must be adjusted. As a result, 
significant time, input and effort from a relatively large number of 
personnel will be required to generate an overall production plan using a 
system in which individual processes are separately being planned. Even 
further, from a practical standpoint, it is extremely difficult to 
completely coordinate production plans for chronologically sequential 
processes or steps in an overall production process (some of which may, 
e.g., be located apart from each other), and the tendency in such 
circumstances is to coordinate such plans only in a very superficial or 
basic fashion. 
As an example of such difficulty, one should consider an upstream process 
which itself consists of a plurality of parallel (in time) component 
manufacturing processes, and a downstream process in which the components 
which are manufactured during the upstream process are then used to 
assemble the final products resulting from the components manufactured 
during the various upstream processes. 
In such an example, the assembly process, i.e., the downstream process in 
this example, typically is programmed to begin only when all of the 
components from the various upstream processes are available and on hand 
to be assembled. 
In such circumstances, the production start time of the downstream process 
must be set to start after providing a sufficient time for any delays 
which may occur during any of the upstream processes, and as a result 
significant and unnecessary time lags can occur during the production of 
final products. In other words, providing sufficient time or allowance, 
between processing steps, for the possible occurrence of such errors, can 
result in unnecessary waste of time in the overall production process. 
The type and volume of products to be produced, and the volume(s) of 
products and components which can be produced in manufacturing production 
lots, will differ in each process. Typical lot size restrictions (i.e., 
the volume of production of one operational run of a given line) represent 
another factor which may delay the assembly of a final product or 
component from a plurality of components or sub-components, respectively, 
i.e., waiting for the completion of one generally parallel process may 
delay the next step even though other components have been prepared, 
particularly if the lot size (i.e., a practical limitation on 
manufacturing speed and volume) has not been taken into account. Such 
delays can accumulate during an overall production plan, such that there 
may well be an steady increase in the amount of time required to develop 
an optimal production plan as the number of production processes (each 
having its own manufacturing limitations) required to produce a finished 
product increases. BENARIEH, U.S. Pat. No. 4,807,108, discloses another 
production process for manufacturing, e.g., an electronic circuit pack. 
Further, an inference planning system used for planning in a manufacturing 
system is disclosed in commonly assigned TANAKA et al., British Patent 
2,219,109, and is also disclosed in its counterpart U.S. patent 
application Ser. No. 08/116,730, which issued as U.S. Pat. No. 5,231,620 
on Jun. 14, 1994. 
Both United Kingdom Patent No. 2,219,109 and U.S. Pat. No. 5,321,620 are 
expressly incorporated by reference herein in their entireties. 
SUMMARY OF THE INVENTION 
Accordingly, one object of the present invention is to provide a production 
plan generating method and a related apparatus for rapidly developing an 
optimal production plan for a plurality of interrelated production 
processes or steps, which takes the respective limitations of the 
processes, and the relationship between the steps, into account when 
generating an overall production plan for producing a final product. 
In order to achieve this object, a production plan generating method is 
provided in accordance with the present invention which first generates a 
production plan for those process steps which are plannable based upon the 
receipt of basic data relating to, e.g., the production equipment to be 
used in such processes, process data which is specific to each process, 
and data relating to the goods to be produced. Thereafter, the method 
involves generation of a production plan for those processes which are 
plannable using previously generated production plan data and the 
above-noted three types of data. Thereafter, this latter planning step is 
repeatedly executed in order to generate production plans for the 
remaining steps of the process, while all the time accumulating the 
generated production plan data for each of the required process steps. 
More particularly, when there are a plurality of chronologically sequential 
process steps in a production process, the production plans for the 
downstream processes, i.e., the processes which occur later during the 
production of a final product, are generated first. Thereafter, final 
parameters for the data relating to "needs," i.e., the product part number 
and/or type, and the quantity of such products which are to be produced 
during the upstream processes, and whether such upstream processes are to 
be divided or combined, are then generated; these final parameters are 
based upon the production plan data which has already been generated for 
the downstream processes, component configuration data for controlling the 
production or various parts and components at each step of the production 
process, process data for the upstream processes, and inventory data for 
the downstream processes. Production plans for each of the upstream 
processes are then sequentially generated (until a plan for the earliest 
in time step has been generated) in order to satisfy the "needs" data. In 
other words, plans are sequentially generated for all required products 
and components, in a chronological order which is opposite to the order in 
which the steps need to be performed to produce a final product. 
In order to sequentially develop production plans for a plurality of 
processes, progressive control of plan generation is performed using the 
process data, process/process limitation data, and production plan 
completion data for each process. This makes it possible to search for and 
identify any processes for which a production plan has not yet been 
generated, and for those processes which will not be restricted by the 
limitations of other processes for which a production plan has not yet 
been generated, in order to be able to identify the next processes or 
steps for which production plans are to be generated. 
In order to achieve these and other objects of the present invention, the 
production plan generator in accordance with the present invention 
comprises an input device for entering basic data relating to production 
equipment, process data specific to each of the plural processes or steps 
involved in the overall production process, and produced goods data, first 
memory means for storing the entered basic data, process data and produced 
goods data, and a first production plan generator for determining the 
processes for which a production plan can be generated based upon only the 
basic data, the process data, and the produced goods data stored in the 
first memory means. The generator also includes means for generating 
production plan(s) for the selected process(es) A second memory is 
provided for storing the production plan data which is generated and then 
output by the first production plan generator, and a second production 
plan generator is provided for determining the processes for which a 
production plan can next be generated based upon the basic data, the 
process data, produced goods data, and the previously generated production 
plan data which is stored in the second memory means. The second 
production plan generator generates production plan(s) for selected 
process(es) or steps, and stores the production plans which result in the 
second memory, and then repeats this sequence in order to generate 
production plans for all of the remaining processes which are required in 
order to produce a desired final product. 
By using such a production plan generating method, production plans are 
first generated for those processes among the plural processes that can be 
scheduled based strictly upon known conditions, e.g., the basic data 
related to the production equipment to be used in the process, process 
data which is specific to each process, and produced goods data. 
Production plans are then generated for those processes which can be 
planned using the resulting "pre-generated production plan data", which is 
supplemented as needed by certain known condition data. The production 
plans which result from this last generation of plans are then accumulated 
as previously generated production plan data, and this process is repeated 
for all of the remaining steps or processes in the overall production 
process until production plans have been generated for all such processes 
which must be performed in the production process. As a result, production 
plans are generated in such an order that priority (in terms of the time 
when the plans are generated) is given to those processes for which 
production plans can be generated based only upon known conditions, and 
which are not dependent upon the chronological, spatial, or other 
relationship which exists between various production processes or steps 
(e.g., the ultimate or other downstream manufacturing step). In this way, 
the requirements that must be met for all of the remaining processes are 
gradually satisfied, and a coordinated plan is developed which will be 
appropriate for the overall production and for all of the process steps 
required. 
Further, an optimal production plan which minimizes the time lag between 
chronologically sequential processes can be generated for manufacturing 
processes involving the assembly of a plurality of components, 
manufactured in plural upstream processes, into a single final product or 
part in a downstream process. Such an optimal plan will result if, when a 
plurality of chronologically sequential processes are used, the production 
plans for downstream processes are first generated, and thereafter "needs" 
data, which includes the product model number or type, and the quantity or 
volume of goods which need to be produced in the upstream processes, as 
well as whether such processes are to be divided or combined, is then 
generated. Such generation is based upon, e.g., the previously generated 
production plan data for the downstream processes, component configuration 
data relating to component part or type numbers in each step of the 
process, process data relating to the upstream processes, and inventory 
data relating to the downstream processes. This process thus serves to 
generate production plans for the upstream processes, which will satisfy 
the final parameters which are necessary to complete the production of the 
final product by the system in an efficient fashion. 
Further, appropriate production plans for each process or step can be 
generated in accordance with known conditions at any given point in time, 
without error, and in an appropriate sequence, by monitoring the progress 
of production plan completion based upon process data, process step 
requirements data, and production plan completion data for each process; 
identifying those processes or steps for which production plans are still 
incomplete and whose plans are neither limited by nor dependent upon other 
processes for which production plans have not been generated, and 
thereafter defining these identified processes as the next processes for 
which production plans are to be generated during the sequential 
development of production plans for the plurality of processes or steps 
required to manufacture a given final product. 
Thus, by using a production plan generator in accordance with the present 
invention, basic data relating to production equipment, process data which 
is specific to each of the plurality of processes or steps, and produced 
goods data are stored in a first memory as such data is entered via an 
input device. The processes for which a production plan can then be 
generated are thereafter determined by the first production plan 
generator, based only upon the data which is stored in a first memory 
area, then generated, and thereafter stored as pre-generated production 
plan data in a second memory area. A second production plan generator 
thereafter determines the processes for which production plans can then be 
generated, based upon data which is stored in the first memory and the 
pre-generated production plan data which is stored in the second memory, 
generates production plan(s) for the selected process(es), and then stores 
the resulting production plans in the second memory area. The second 
production plan generator repeats this sequence in order to generate 
production plans for all remaining processes for which production plans 
have not yet been generated. As a result, simply by inputting initially 
known data, production plans can be automatically generated, with plans 
first being produced for those process steps for which production plans 
can be generated based only upon known conditions, irrespective of the 
chronological, spatial or other relationship between production steps. 
This system thus gradually meets all of the requirements that must be 
satisfied for all of the remaining processes or steps, and is thereby 
develops an overall production plan which is appropriate for all of the 
processes needed to manufacture a final product. 
A production plan generating apparatus is provided for generating a 
plurality of production plans, in sequential order to produce a product, 
for a downstream process in which said final product is to be produced, 
and for a plurality of upstream processes for producing components which 
are used in forming said final product from a plurality of components. The 
production plan generating apparatus comprises an input device for 
inputting initial data including data relating to said downstream process, 
a first memory area for storing said initial data, a first production plan 
generator for generating data relating to a first upstream process which 
needs to be performed, in order to produce said final product, before said 
downstream process is performed, said first production plan generator 
generating a production plan for said first upstream process, based upon 
at least some of said initial data, a second memory area for storing said 
plan generated by said first production plan generator, and a second 
production plan generator for generating a production plan for a second of 
said upstream processes, wherein the plan which is generated by said 
second production plan generator is based upon at least the plan stored in 
said second memory area, and wherein said second upstream process must be 
performed before said first upstream process is performed during 
manufacture of said final product. 
The second production plan generator comprises means for sequentially 
generating a production plan for each of an additional plurality of 
upstream processes, wherein each successive plan generated by said second 
production plan generator is based at least partially upon the production 
plan generated for a sequentially previous upstream process. The initial 
data includes basic data relating to the equipment required to produce 
said final product and all of said components, and production data 
specific to each component and process which is required to produce said 
final product. The apparatus further comprises a parameter generator for 
generating a plurality of process parameters for use by said second 
production plan generator in generating production plans for said second 
and additional upstream processes. 
The parameter generator comprises a system for generating preliminary 
parameters, said preliminary parameters comprising the types of specific 
components which must be produced in a sequentially previous upstream 
process, and the exact quantity of said specific components which will 
need to be produced in said sequentially later upstream process, and a 
system for generating final parameters which comprise the actual 
quantities of the specific components which must be produced during each 
of the second and additional upstream process. 
The invention is also directed to a production plan generating method for 
generating production plans in a chronologically sequential order, for a 
downstream process in which a final product is to be produced, and for a 
plurality of upstream processes which are required to form said final 
product from a plurality of components. The production plan generating 
method comprises the steps of inputting initial data including ultimate 
downstream process data which relates to the final product to be produced, 
storing said input initial data, generating first upstream process data 
based upon the initial input data, said upstream process data relating to 
one of said upstream processes which precedes production of said final 
product, storing said first upstream process data, and generating 
additional upstream process data which relates to an additional upstream 
process which occurs during production of said final product, said 
additional upstream process data being based at least partially upon said 
first upstream process data, wherein said additional upstream process must 
be performed before said first upstream process is performed during 
production of said final product. 
The method further comprises repeating step (e), based upon the most 
recently generated additional upstream process data, until no further 
Processes need to be performed in order to form said final product. 
In another aspect, the present invention is directed to a system for 
generating an overall production plan for producing final products, 
wherein each of said final products is comprised of a plurality of 
components, said system being provided for generating a plan to determine 
the timing of a plurality of sequential process steps used to produce said 
final products, and the volume of final products and components which are 
to be produced. The system comprises a device for inputting data relating 
to the volume of each final product required to be produced, and the date 
by which said required volume of said final products are required to be 
produced, a memory for scoring a data tree for each final product to be 
produced, said data tree comprising information regarding the number and 
types of components which are required to produce each said final product, 
for storing the sequence in which said process steps must be performed in 
order to produce each said final product, and for storing data relating to 
the time required to perform each of said sequential process steps, and a 
production plan generator apparatus for generating separate production 
plans for producing said final product and performing each of said steps, 
said overall production plan including the sequence in which said steps 
are to be performed and the volume of components which must be produced 
during each step, as well as the date by which each step must be performed 
in order to produce said final product in the required volume and by the 
required date. 
The device for inputting data comprises means for inputting data regarding 
a plurality of different final products. At least one of said plurality of 
final products has at least one component which is required to be used to 
manufacture said at least one final product in common with a second one of 
said plurality of different final products. Each of said final products is 
to be manufactured in accordance with a predetermined sequence, wherein 
said sequence involves a downstream process step in which the final 
product is assembled, and a plurality of sequential upstream steps in 
which the components which are required to manufacture said final product 
are assembled, wherein said production plan generator apparatus includes a 
first production plan generator and a second production plan generator, 
said first production plan generator comprising means for generating a 
plan for producing a final product in accordance with said downstream 
process step, based upon data input by said device for inputting data, and 
wherein said second production plan generator comprises means for 
generating a plan for performing each of said upstream process steps in 
accordance with at least some of the data input by said device for 
inputting data, and in accordance with data relating to an immediately 
preceding process step which is required to produce said final product. 
The production plan generator apparatus includes a parameter generator, 
said parameter generator including means for generating a preliminary 
parameter and means for generating a final parameter, said means for 
generating a preliminary parameter including means for extracting data 
regarding an immediately preceding downstream process production plan, 
process data, and tree construction data relating to the components or the 
final product to be produced, from said memory, said final parameter 
generator comprising means for extracting inventory data and component lot 
size manufacturing data from said memory. Each of said production plan 
generators comprises means for generating a production plan for 
controlling a plurality of machines used in different process steps 
required to produce said final product. 
Means are provided for controlling production of said final products in 
accordance with said overall production plan generated by said system. The 
system includes a printer for printing each production plan which is 
generated by said system, and a display device or displaying each 
production plan which is generated by said system; and the memory 
comprises a RAM. Means are also provided for controlling production of 
each final product in accordance with said overall production plan 
generated by said system. 
A method is also provided for generating an overall production plan for 
producing final products each comprised of a plurality of components. The 
overall production plan governs the production of said components and said 
final products in a production process including a plurality of sequential 
process steps, said sequential process steps including a downstream 
production process step which produces said final products, and a 
plurality of upstream production process steps for producing said 
components. The method comprises inputting and storing basic data relating 
to said production process and production data regarding the volume of 
said final products which is required to be produced, and the date by 
which said required volume of final products is required to be produced, 
generating and storing a first production plan for producing said final 
products in said downstream production process step, said first production 
plan being based upon at least some of said basic data and said production 
data, generating and storing a second production is plan for a first 
upstream process step preceding said downstream process step, based upon 
at least some of said basic data, said production data and said first 
production plan, determining whether any additional upstream processes 
require planning, and if any additional upstream processes are identified 
as requiring planning, generating and storing a third production plan for 
an additional upstream process step which has not yet been planned and 
which must be performed before the first upstream stem is performed during 
manufacture of the final products, based upon at least some of said basic 
data, said production data, and the second production plan. 
The method further comprises generating and storing overall production 
plans for a plurality of final products, wherein at least two of said 
final products to be produced have at least one component in common. The 
method further comprises printing said overall production plan, and 
displaying said production plan. 
The method further comprises repeatedly determining whether any required 
upstream process still require planning, and then generating a production 
plan for the next sequential upstream process step to be performed in 
producing said final product, each time that any upstream process steps 
are determined to still require planning. Then, a final parameter relating 
to the volume and type of components which must be produced in the next 
process step to be planned is generated, prior to the generation of each 
of said upstream production plans. 
The method further comprises producing said final parameter by extracting 
from a memory production plan data for the sequentially preceding plan, 
construction tree data relating to the component which must be next 
produced, and process specific data, generating a preliminary parameter, 
and modifying the preliminary parameter, in order to generate a final 
parameter after extracting inventory data and component lot size from 
memory. Then, the method involves controlling the production of each of 
said final products and each of said components in accordance with said 
overall production plan. 
The present application is based upon Japanese Patent Application Serial 
No. 4-318,822, which was filed on Nov. 27, 1992, the entire content of 
which is expressly incorporated by reference herein.

DETAILED DESCRIPTION OF THE DRAWINGS 
The system of the present invention is adapted to be used for manufacturing 
any type of product, particularly with respect to products involving a 
plurality of assembly lines or processing steps which must be coordinated. 
This process and assembly line control system are thus designed to 
coordinate the production of finished products from a plurality of 
parallel and/or sequential assembly lines or manufacturing different 
components which are used to make final products; and can be used either 
with a single assembly line or with a plurality of assembly lines. While 
the present invention is applicable to many types of products made in 
accordance with such processes, Applicants note, by way of non-limiting 
example, that the production planning process could be used, e.g., for 
generating an overall production assembly plan for producing printed 
circuit boards, televisions, or automobiles. With such products, it is 
possible that related products (e.g., a 25" television and a 20" 
television, two different automobile models manufactured by the same 
company, or printed circuit boards having a similar base but having 
different components) may include one or more component parts in common. 
The present invention is not only adapted to be used to generate a 
production plan for a single finished product, but is also well adapted 
for use in situations in which a company may be faced with the need to 
produce a number of different products at the same time, which products 
have one or more components in common. 
In the case of a printed circuit board, e.g., the finished or downstream 
product may be the printed circuit board, with the components comprising, 
for example, a laminated base, one or more modules, and one or more 
electronic components. If the manufacturing process is directed to 
producing televisions, for example, the final products could be different 
size television sets, e.g., a 25" television and a 20" television, with 
common components including, e.g., certain circuit boards, and different 
components including, e.g., different LCD assemblies. As another 
non-limiting example herein, the final product could include different 
automobile models of a single automobile manufacturer, with the different 
components including doors and common components including radios, 
switches or door handles. 
Thus, as can be seen from the above examples, the applicability of the 
present invention is quite wide in scope, and none of the examples which 
have been given herein is intended to limit the application of the 
invention. The application is thus broadly applicable to planning 
production for a variety of manufacturing processes, as can be used in the 
fashion set forth hereinafter. 
Referring now more specifically to the invention as described in FIG. 1, an 
illustrative embodiment of a production plan generating apparatus/assembly 
according to the present invention is illustrated. This apparatus includes 
an input device 14, e.g., a keyboard, for entering initial known data, and 
a memory 11 having a basic data storing area 21, a process specific 
production data storing area 22, and a plan result data storage area 23. 
The production plan generating apparatus further comprises a central 
processing unit (i.e., CPU) 1, a display device 12 and a printer 13, for 
respectively displaying and printing a generated production plan. 
CPU 1 has a first production plan generator 2, a parameter generator 4 for 
generating a variety of parameters used in the production planning 
process, and a second production plan generator 3. 
The first production plan generator 2 generates production plans for those 
processes that can be planned using only initially known data, e.g., basic 
data 21 and process specific production data 22. In other words, the first 
production plan generator 2 is provided for generating appropriate 
production plans as part of an overall, final production process, based 
upon parameters which are in turn based upon data received from the basic 
data storage area 21 and production data storage area 22. Thus, production 
plan generator 2 is provided for generating production plans which are not 
dependent upon the requirements of any other processes or steps, and which 
can be generated before receiving information relating to such processes 
or steps. 
Second production plan generator 3 is provided for thereafter generating 
production plans for those processes that can only be properly planned 
using both the initially known data and production plan data which is 
previously generated by the first production plan generator 2. In other 
words, second production plan generator 3 is provided for generating 
appropriate production plans for production processes, other than the 
final (i.e., the downstream) actual production process, based upon 
parameters received from parameter generator 4. This second generator thus 
generates production plans for those upstream production processes or 
steps which are dependent upon the requirements and capabilities of later 
performed (i.e., downstream) production processes. 
Memory 11 includes a plurality of information storage areas, and thus 
stores a variety of data, including initial known data which is input via 
input device 14, plan result data which is generated by the first 
production plan generator 2 and stored in data storage area 23, as well as 
plan result data which is generated by second production plan generator 3, 
and then stored in storage area 23. 
Basic data storage area 21 stores data/information relating to production 
equipment used in the various processes in an overall manufacturing 
process for a given final product, such as the number of buildings which 
the factory includes, the number of assembly lines located in each 
building, and the number and type of machines in each line. 
Production data stored at storage area 22 comprises, in this embodiment, 
process data which is specific to each process or step required to 
manufacture a final produce, as well as data relating to the goods which 
are being produced (the latter data being referred to hereinafter as 
"produced goods data"). More specifically, production data includes the 
number of final goods or products (and, where applicable, the model number 
or type) to be produced, the due date by which each of the final products 
must be produced, and component tree configuration data which incorporates 
information relating to the number and type of components which are 
required to make a final product, illustrated in a tree and branch 
configuration which also includes information relating to the number and 
type sub-components required to manufacture each component. Production 
data stored at area 22 further includes assembly step data which specifies 
the specific machines which are required to manufacture various components 
as well as the final product, production rate data which specifies the 
amount of time required to make each component or final product which is 
to be produced in the production process, lot size data, which specifies 
the volume of each component or final product which can be produced in a 
single working operation run, the time (e.g., number of hours) required 
for each such working operation run, inventory data relating to the number 
of final products and/or components which have already been produced, and 
other relevant data relating to the production process. 
As noted previously, any given manufacturing process includes a final 
downstream process or step, which involves the assembly of the final 
product to be manufactured, an initial upstream process or step in which 
certain sub-components or components are manufactured, and a plurality of 
intermediate processes or steps. Processes or steps are referred to herein 
as upstream or downstream with respect to the time at which they take 
place during an overall manufacturing process; and, therefore, other than 
the first and last steps, all steps can be considered both upstream and 
downstream. Applicants further note that other than the final downstream 
assembly step, all other steps can be considered upstream steps; and that 
other than the first and last steps in a process, each other step may be 
either upstream or downstream, dependent upon the step that it is being 
related to. 
The process or step that can be planned by the first production plan 
generator 2 is generally considered a "downstream" process, and those 
processes which can be planned by the second production plan generator 3 
are generally referred to as upstream processes in this specification, 
since the second generator uses the data from previous "downstream" 
processes that have been planned during a previous calibration or 
calculation. More particularly, first production plan generator 2 is 
utilized for generating "downstream process" data using "ultimate 
downstream process" data, with the second production plan generator 3 
being repeatedly used to generate upstream process data using intermediate 
downstream process data, and so on. In this case, ultimate downstream 
process data is data input through input device 14, i.e., data relating to 
the production of the final product which is to be produced by the plan, 
with intermediate downstream process data being internally developed data, 
relating to the production plans for various production steps, which is 
prepared by the first production plan generator 2 or (later) by the second 
production plan generator 3. 
An upstream process is a process which may be affected by, i.e., which will 
be limited to or restricted by, other production plan processes; thus, the 
upstream, processes can be determined only after the closest adjacent (in 
time) downstream process has been planned. When it is determined that a 
plurality of processes are ready to be planned by the first production 
plan generator 2 (e.g., when X and Y data are together received) or to be 
next planned by the second production plan generator 3, the production 
plans for these processes can be developed in any order. This could occur, 
e.g., with respect to process steps which occur at parallel levels within 
a production process, for which the specific order of performance is not 
critical. 
FIGS. 4a-4c represent three different planning levels used in generating a 
plan for producing 100 final products X and 100 final products Y, e.g., 
where X could comprise a 25" television and Y could comprise a 20" 
television. Alternately, X and Y could each be final products to later be 
assembled together. As shown in the far left hand portion of FIG. 4a, data 
input at 14 in FIG. 1 will show that one customer requires 100 of product 
X by March 1, with another customer requiring 100 of product Y by March 2. 
This data for products X and Y is input through input device 14 and is 
referred to as "ultimate downstream process" data, since it includes the 
customer date and quantity requirements for final products. The production 
data memory area 22 includes component tree configuration data (shown in 
FIGS. 5a and 5b, respectively) for the final product X and final product 
Y. This component tree information includes the number of final products 
which are required (e.g., 100 of X and 100 of Y), as well as showing the 
number of components and/or sub-components which are required to make each 
final product X and Y, respectively. In both of these figures, the numbers 
shown in parentheses show the number of parts necessary to make a single 
component or part represented by an immediate parent node on the tree. For 
example, a single final product X requires two components a and one 
component b; and to make each component a, two sub-components A and three 
subcomponents A are required. Therefore, to make one final product X, sour 
A and six A will be necessary. The numbers in each tree which are provided 
under the numbers in parentheses indicate the normal lot size for each 
component, i.e., the number of components which will be produced during a 
single working operation run. As shown in FIG. 5a, during one working 
operation run, 300 components "a" will be produced, even though only 200 
are necessary to make the desired 100 final products X. The difference 
between these two numbers, i.e., 300-200=100, will later be stored as 
excess inventory and used in further process planning. 
As shown in FIG. 5b, each product Y requires one component a and three 
components c, with each component c requiring one component A and two 
components .gamma., with each component "a" again requiring three .beta. 
and two .alpha.. 
As shown in FIG. 4a, the final products X and Y are assembled or produced 
by different stations or machines A1 and A2, respectively. The number of 
Final products X and Y which are required, and the dates (March 1 and 
March 2, respectively) are input as customer requirements (i.e., ultimate 
downstream process data) via input device 14. By using this input data, 
the dates then indicated in FIG. 4a, namely, the operation dates of 
February 27--February 28 for machine A1 and the operation dates of 
February 28--March 1 for machine A2 are calibrated/calculated by first 
production plan generator 2. Plan generating systems and subsystems which 
may be used to carry out the functions of the first production plan 
generator 2, as well as second production plan generator 3, are described 
in commonly assigned British Patent 2,219,109 (and its counterpart U.S. 
application), which has already been incorporated by reference herein in 
its entirety. 
The production plan which is illustrated in FIG. 4a, and which is obtained 
by first production plan generator 2, is scored as a plan result in plan 
result data storage area 23. The data which is provided in FIG. 4a, 
relating to machines A1 and A2, will then be considered as intermediate 
downstream process data for calibrating the upstream process data relating 
to the other machines involved in the adjacent upstream processes, i.e., 
in the next step of the process, machines B1, B2 and B3 will be used, as 
described hereinafter. For purposes of facilitating the manner in which 
the present product plan generating system and method operate, only three 
levels of machines, namely, levels A, B and C, are illustrated. Each of 
the numbers A1-A2, B1-B3 and C1-C3 represent a different machine or 
station for producing different components or final products. 
FIG. 2 illustrates the details of the parameter generator 4 which is used 
for determining a variety or parameters needed to plan the sequential 
upstream process(es), using data collected from data areas 21, 22 and 23, 
as shown in FIG. 1. Parameter generator 4 comprises a downstream process 
production plan data extractor 32 for extracting downstream process 
production plan data from the plan result data that was generated during a 
previous operation cycle, i.e., for a sequentially later (during 
production) downstream process; a component tree configuration data 
extractor 34 for extracting a portion of tree configuration data, examples 
of which are illustrated in both FIGS. 5a and 5b, from production data 
area 22, in order to obtain data indicative at the number and type of 
parts which will need to be produced in the upstream process(es); and a 
process data extractor 33 for extracting process data (e.g., time and/or 
production capability) related to machinery that is necessary for making 
products in the upstream process that occurs just prior to the downstream 
step for which downstream process data was extracted by extractor 32; and 
a preliminary parameter generator 31. Based upon the extracted downstream 
production plan data, the process/machinery data, and data which indicates 
the number of component parts to be produced in the next upstream process, 
preliminary parameter generator 31 will generate preliminary parameters, 
such as the part numbers of the parts that must be produced during the 
next upstream process(es) and the exact quantities of the corresponding 
parts that will need to be used to effect the production plans for the 
downstream processes which will occur later in the chronological, 
operational sequence of the manufacturing process. 
Parameter generator 4 also comprises an inventory data extractor 35 for 
extracting inventory data with respect to any of the parts or components 
that must be produced in the upstream process, i.e., data relating to 
whether there is any inventory of any such parts, a lot size data 
extractor 36 for extracting data regarding the lot size in which 
components/parts that are to be manufactured in the various upstream 
processes are normally produced, a final parameter generator 37, and a 
final parameter memory 38. Based upon the amount of inventory available, 
i.e., the inventory data, and the lot size data, the preliminary 
parameters generated at 31 are revised to final parameters which give the 
actual quantity of each given part number or type that must be 
manufactured in any given upstream process. In other words, preliminary 
parameter generator 31 determines the volume of components which must be 
produced to satisfy the requirements of the generated downstream step or 
process plan, and the final parameter generator modifies these parameters 
by imposing practical limitations, resulting from lot size manufacture and 
inventory, upon such preliminary parameter(s). The final parameters are 
then stored in memory 38 and are used by second production plan generator 
3 to generate schedules for manufacturing components during the various 
upstream processes or steps. 
Thus, in order to generate a parameter for use by the second product plan 
generator, FIG. 10 illustrates the basic steps performed by parameter 
generator 4. First, at step S31, downstream plan data, the appropriate 
tree construction data, and process/machinery data are extracted from 
memory, and at step S32, one or more preliminary parameters are generated 
which are based upon the production requirements imposed by the downstream 
process plan, the amount of time required as determined from the process 
data, and the number of components and/or sub-components required to be 
produced, as determined from the tree construction data. Thereafter, at 
step S33, inventory data and lot size data are extracted from memory 11, 
and one or more final parameters are generated which impose practical 
manufacturing limits upon the preliminary parameter(s) which were 
generated. More particularly, based upon the lot size which can be 
produced, less any excess inventory of a final product, component or 
sub-component which has been stored and retained in memory, a final 
parameter representing the number of components or sub-components which 
are to be produced is generated. 
As a result, production plans for the various upstream processes are 
calculated/determined, based at least in part upon the requirements of the 
production plans previously generated for the previous downstream 
process(es). It is therefore possible to automatically and efficiently 
produce an overall appropriate production plan for interrelated upstream 
and downstream processes and steps, i.e., for planning the coordinated, 
efficient production of all required components, sub-components and final 
product(s). 
Thus, parameter generator 4 serves to extract the appropriate data from 
memory 11, based upon the next level component to be manufactured (from 
the tree construction data) and the amount of time, e.g., that it takes to 
perform each process and transfer a product from one process to another 
(from the process data extractor 33), and information relating to the 
number of components or sub-components required, from downstream process 
production plan 32. Thus the preliminary parameter generator 31, based 
upon this information, determines what components need to be manufactured 
next, how much time it will take to transfer those components, and based 
upon the data provided from the adjacent (timewise) downstream process 
production plan which has been previously generated, and the tree 
construction data, the quantity of components which need to be made. This 
information is then sent to the final parameter generator 37, which 
modifies that information by reducing the number of components which need 
to be manufactured in view of any excess inventory which exists, and by 
then taking the lot size for each component into account, from lot size 
data extractor 36, in order to determine how many lots of each component 
must be made (which will likely increase the number of components to be 
produced). This data is stored in the final parameter memory 38, and is 
thereafter sent to second production plan generator 3. 
The result of the operations which are performed by parameter generator 4 
and by the second production plan generator 3 is illustrated in FIGS. 4b 
and 4c. As shown in FIG. 4b, based upon known data, i.e., based upon the 
intermediate (i.e., sequentially later) downstream process data determined 
with respect to machines A1 and A2, and the tree configuration data shown 
in FIGS. 5a and 5b, upstream process data relating to machines B1, B2 and 
B3 are determined. Particularly, the lot size, i.e., 300 pieces of part 
"a", can be produced by machine B1 if it operates from February 22 to 
February 26, in order to supply enough components (a) to machine A1 in 
time for it to begin its operation on the required date of February 27. Of 
the 300 pieces which are produced, 200 will be supplied to machine A1 by 
February 27, and 100 need to be supplied to machine A2 for the manufacture 
of final product Y, by February 28. It should be noted that it is 
coincidental that the 300 lot size for component (a) equals the total 
requirement of machines A1 and A2 in this example. For example, if the 
requirement of machine A2 had also been 200 (in which case 200 of final 
product Y would have been required), then it would have been necessary to 
manufacture 600 or component "a" (two lots of 300) in order to supply the 
400 components (a) which would have been required in that case. 
As can further be seen, one lot size (i.e., 100 pieces) of component "b" 
will be produced by machine B2, which will need to operate for two days, 
i.e., on February 25 and 26, in order to provide 100 components "b" to 
machine A1 in time for it to begin operation on February 27. Further, one 
lot size, i.e., 300 pieces of component "c", will be produced by machine 
B3, which will need to operate from February 24 through February 27 in 
order to supply 300 components "c" for the manufacture of 100 final 
products Y in a timely fashion, since machine A2 needs 300 components "c" 
on or before February 28. The production plan shown in FIG. 4b is 
generated by production plan generator 3 and is stored as a plan result in 
data storage area 23 of memory 11. The data which is illustrated in FIG. 
4b, particularly as it relates to machines B1, B2 and B3, will then serve 
as the next intermediate downstream process data for calibrating and 
determining the next sequential upstream process data which relates to 
machines C1, C2 and C3, all as shown in FIG. 4c. 
FIG. 4c illustrates the next step for calibrating upstream process data. In 
the present example, this is the last step of the final upstream data 
which will be calibrated; although for any given production process, there 
can be numerous additional such steps. 
As shown in FIG. 4c, upstream process data relating to machines C1, C2 and 
C3 is determined and calibrated based upon known data, i.e., based upon 
the intermediate downstream process data plan which has already been 
generated with respect to machines B1, B2 and B3, and the tree 
configuration data shown in FIGS. 5a and 5b. As shown in this plan, 600 
sub-components .alpha. (e.g., two for each component a) will need to be 
produced, as will 1200 subcomponents component .beta. (900 for component 
a, or three for each such component a, and 300 for component c, or one for 
each component c), and 600 .gamma. components will need to be made (in 
order to supply two for each component c). These determinations are made 
in a virtually identical fashion to the determinations which were made 
with respect to machines B1, B2 and B3. 
For example, 600 sub-components a will have to be sent to machine B1 by 
February 20, and thus must be completed by February 19. Based upon the 
process data which is extracted by process data extractor 33, it will take 
a period of time between February 15-February 19 to manufacture a 
sufficient quantity of sub-components .alpha. to satisfy the requirement 
to make component "a" in sufficient quantity at machine B1, starting on 
February 20. Thus, 600 pieces (i.e., two lot sizes) of component or part 
.alpha. will be produced by machine C1, which will be operated from 
February 15-February 19, and all 600 pieces of component a will be 
supplied to machine al by February 20. 
Furthermore, two lot sizes, i.e., 1200 pieces of sub-component .beta., will 
be produced by machine C2, which will need to be operated from February 
13-February 19 to produce the same in time to supply machines B1 and B3 as 
required. Of those 1200 components .beta., 900 will need to be supplied to 
machine B1 for manufacture of 300 components "a" by February 19, and 300 
will need to be supplied to machine B3 by February 23. Additionally, two 
lot sizes, i.e., 600 pieces of sub-component .gamma., will need to be 
produced by machine C3 in a time sufficient to supply them to machine B3 
by February 23. Thus, 600 sub-components .gamma., will be produced by 
machine C3, which will need to be operated prom February 16-February 20, 
and all 600 pieces will be supplied to machine B3 by February 24. 
The production plan which is illustrated in FIG. 4c was produced by second 
production plan generator 3, and is stored as a plan result in data 
storage area 23. The data which is shown in FIG. 4c, particularly with 
respect to machines C1, C2 and C3, thus serves as starting process data, 
e.g., as "ultimate" upstream data, which is required to produce 100 pieces 
of each of the final products X and Y by the customer required due dates 
of March 1 and March 2, respectively. 
As is noted above, the first step in preparing an appropriate plan is to 
input the basic data 21 which relates to the production equipment being 
used, production data 22, i.e., process data which is specific to each 
process, and produced goods data, through input device 14. This input data 
can be referred to as data for "known conditions," and is stored by memory 
11. 
When CPU 1 is operated, processes/steps that can be planned based only upon 
data stored in basic data storage area 21 and production storage area 22 
in memory 11 will first be determined by the first Production plan 
generator 2. This first plan generator then proceeds to generate 
production plans for the selected processes and stores the resulting 
pre-generated production plan data for all such steps as plan result data 
23 in memory 11. 
Second production plan generator 3 then determines which processes can be 
next planned based upon the data (i.e., basic data 21, production data 22 
and plan result data 23) which is stored in memory 11, generates 
production plans for the next selected processes, and cumulatively stores 
the resulting pre-generated production plans in data storage area 23 of 
memory 11. The second production plan generator 3 repeats the process of 
plan determination-(i.e., (i.e., identifying the next step to be 
planned)-plan generation-data storage by following all of the process 
steps sequentially backwardly (i.e., in an order inverse to that in which 
they will be performed), for all remaining processes and steps, until 
production plans have been generated for all steps/processes, components, 
sub-components and final products which are required to produce the final 
product(s) 
This process is illustrated in FIG. 7a, which shows the first step (the 
input and storage of basic and production data at step S20), the 
generation and storage of the first level production plans by first 
production plan generator 2 at step S21, and the generation and storage of 
all subsequent levels of production plans by second production plan 
generator 3, at step S22. After second production plan generator 3 stores 
the plan for each downstream process, it is then determined, at step S23, 
whether there are any further components or sub-components for which plans 
need to be generated, and if additional plans need to be generated, then 
step S22 will again be executed. If no additional plans need to be 
generated, then the overall plan is printed by printer 13, or displayed on 
a terminal or other display device 12, or forwarded to an automated 
control facility. As a result, simply by inputting initially known data, 
production plans can be automatically generated, with priority given to 
those processes for which production plans can be generated based upon 
known conditions, irrespective of the chronological, spatial or other 
relationships between production processes; and thereafter, plans for all 
of the other required steps in the overall manufacturing process can be 
generated in a successive fashion. 
Instead of the flow operation shown in FIG. 7a, the flow operation shown in 
FIG. 7b can be used (and, at present, is a preferred method of 
implementing the present invention). The difference is that step S22 is 
shifted after "YES" selection of step S23. 
FIG. 3 is a flow chart which represents a specific process for 
determining/identifying which processes can next be planned, using the 
pre-generated production plan data, in order to sequentially generate all 
production plans in an appropriate fashion. This process is executed by 
the second production plan generator 3, based upon the initially known 
data and the production plan data which is generated for the processes 
that are plannable based upon the initially known data, while generating 
final parameters for use in the planning of upstream processes. 
As shown in FIG. 3, the completion status of production plans is monitored 
at process selection step 41, based upon the final parameters (which have 
taken process data 33' into consideration) stored in memory 38, which are 
obtained during preliminary parameter generation step 31', and final 
parameter generation step 37' shown in FIG. 3, and progress data 43, which 
tracks the completion of production plans for processes/steps that can be 
planned using only the process data and known data. This makes it possible 
to determine those processes for which production plans have not yet been 
generated, but which are no longer dependent upon another process for 
which a production plan has not yet been generated, i.e., it assists in 
determining those processes which are not then limited by, or dependent 
upon, any other process, and which thus could then be generated. All such 
processes are placed next on the queue for process selection 41. 
In production plan generation process 42, the operation of second 
production plan generator 3 is carried out. More particularly, a 
production plan is generated for the preceding process (i.e., the next 
upstream process) selected by process selection 41, based upon basic data 
21', production data 22', and plan result data 23'. If the process for 
which the production plan is determined is yet another upstream process 
for a downstream process, the preliminary parameter generation step 31' 
and the final parameter generation step 37' will be run based upon the 
most recently generated production plan. If no such further upstream 
process then exists, the procedure will move back directly to the process 
selection 41. This loop is then repeated as required until production 
plans have been developed for all processes. 
The data which is extracted by the parameter generator 4 includes tree 
construction data 34', lot size data 36', inventory data 35' and process 
data 33'. 
As a result, appropriate production plans for each process/step can be 
developed without error, and in appropriate order, based upon the known 
conditions at any point in time. 
FIGS. 8, 9a and 9b are schematic representations of one way in which the 
overall plan which is generated, printed and displayed in FIG. 1 may be 
used to control the operation of a process for producing one or more final 
products. In FIG. 8, a control system 50 is shown which controls two 
different production lines, e.g., production line 52 for final product X 
(e.g., a 25" television) and production line 54 for final product Y (e.g., 
a 20" television). Although the exact manner of implementing the control 
of the production lines is not shown herein, it would be possible to 
implement a plan which is generated to control either or both of lines 52 
and 54, either by controlling individual machines or stations in 
accordance with the overall plan generated, or by input into a central 
controller which then would control all such machines or stations. 
The machines or (more likely) stations (each station comprising one machine 
or a plurality of machines) in each of the processes are illustrated 
schematically in FIGS. 9a and 9b and generally correspond to the 
stations/machines shown in FIGS. 4a-4c. More particularly, FIGS. 9a and 9b 
show machines/stations A1 and A2 which are required to assemble the final 
products X and Y, respectively, as part of respective assembly lines 52 
and 54. The required machines/stations for final product X include 
machines B1 and B2, and machines C1 and C2 for producing and supplying 
sub-components to component station B1. For assembly line 54, the final 
product Y which is assembled at station/machine A2 receives components 
from stations/machines B1 and B3. Station B1, in turn, receives 
sub-components from stations C1 and C2, with station B3 receiving 
sub-components from stations C2 and C3. The apparatus and method of the 
present invention can thus be used with production lines having a 
plurality of stations with each station having individual machines or a 
plurality of machines. 
By using the production plan generating method of the present invention as 
described above, it is possible to efficiently develop appropriate 
production plans for all processes because individual production plans 
will be generated in a coordinated fashion in sequential order, with 
priority given to generating plans for those processes for which 
production plans can be generated based upon known conditions at any point 
in time, and which do not depend upon the chronological, spatial or other 
relationship between production processes, thereby limiting the generation 
of production plans for remaining processes while gradually developing 
plans appropriate for all of the processes/steps of manufacturing 
components, sub-components and the final product(s). 
Further, if production plans for downstream processes are generated first 
in a process in which there are a plurality of chronologically sequential 
processes, the parameters, including the product number, type and quantity 
of goods to be produced in the upstream processes, and when the processes 
are to be divided or combined, can then be generated based upon previously 
generated production plan data for the downstream processes, with the 
later generated production plans for upstream processes being generated to 
satisfy those parameters; and, in this fashion, an optimal production 
plan, which minimizes the time lag between chronologically sequential 
processes, can be generated for manufacturing processes which assemble 
components, manufactured in a plurality of upstream process steps, as a 
single product or part in a downstream process. 
Further, by monitoring the progress of production plan completion for each 
process/step, and by identifying for next plan generation, those processes 
for which production plans have not yet been completed, and which can be 
generated without information from another process for which a production 
plan has not yet been generated, appropriate and complete production plans 
for each production step can be generated in accordance with known 
conditions at any given point in time without error and in appropriate 
sequence, efficiently and without (or with minimum) failure. 
By using the production plan generator system in accordance with the 
present invention, a production plan for a plurality of processes or steps 
can be generated easily and within a relatively short period of time 
merely by inputting initially known data, since individual production 
plans can be generated with priority given to those processes for which 
production plans can be generated based upon known conditions, and which 
do not depend upon a chronological, spatial or other relationship between 
production processes in order to produce their respective plans. This will 
satisfy the conditions which limit generation of production plans for 
remaining processes while gradually developing plans which are appropriate 
for all such processes. 
Having thus described the invention, it is apparent that there are other 
variations which are within the skill of one of ordinary skill in the art 
and which should not be regarded as a departure from the scope of the 
invention. Thus, all such modifications as would be within the skill of 
one of ordinary skill in the art are intended to be included within the 
scope of the claims which follow.