Real world modeling and control process
DCFirst Claim
1. A process for modeling a manufacturing plant, which comprises delineating a set of factory operating rules which define how part lots interact with machines in actual operation of the plant, defining the manufacturing plant by specifying machines in the plant and at least batch size and processing time parameters of each machine, defining products manufactured in the plant, providing fabrication sequences consisting of process steps for the products manufactured in the plant, assigning the process steps to the machines, defining at least time and yield characteristics of each process step, identifying which phenomena in the manufacturing plant are stochastic in nature, and assigning distributions and parameters of the distributions to the stochastic phenomena.
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Abstract
A modeling and control process for distributed factories having fabrication sequences starts with a definition of how the factory actually operates, rather than a mathematical theory which ultimately leads to a definition of the plant operation. The process begins by delineating a set of factory operating rules which define how part lots interact with machines in actual operation of the factory. A dynamic model of the factory is selected from a group of specimen models for such factories. The model defines the factory by its machines, products, fabrication sequences, collections of job sets, scheduling rules, and machine reliability parameters. The parameters that describe the specific factory are determined and defined in terms of data structures of the individual factory model. The factory specific model contains descriptions of the dynamic interactions of lots and machines. The behavior of the factory can be simulated in detail. A comparision of such a simulation against actual observation of the factory can be used to refine the model. Because the process begins with a definition of how the factory actually operates, calculations for even very complex-factory simulations, such as integrated circuit fabrication facilities, are simplified so that small computers, such as personal computers, may be employed. The models and simulations can be made accurate enough to allow automatic computer control of the factory using the models and simulations.
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Citations
58 Claims
- 1. A process for modeling a manufacturing plant, which comprises delineating a set of factory operating rules which define how part lots interact with machines in actual operation of the plant, defining the manufacturing plant by specifying machines in the plant and at least batch size and processing time parameters of each machine, defining products manufactured in the plant, providing fabrication sequences consisting of process steps for the products manufactured in the plant, assigning the process steps to the machines, defining at least time and yield characteristics of each process step, identifying which phenomena in the manufacturing plant are stochastic in nature, and assigning distributions and parameters of the distributions to the stochastic phenomena.
- 18. A process for modeling a distributed manufacturing plant which has fabrication sequences consisting of process steps, in which a model describing actual operation of the plant is obtained, which comprises choosing a dynamic model for the plant from a group of specimen sequenced-dynamic-factory models, determining a set of parameters that describe the plant, describing the parameters in terms of data structures of the chosen model, the chosen factory-specific dynamic model containing descriptions of the dynamic interactions of part lots and machines in the plant, simulating the dynamic behavior of the plant using the chosen factory-specific dynamic model, comparing predictions obtained with the simulation using the model with observed manufacturing trends in the plant, and using the comparison to refine the model.
- 34. In a process for dynamic, real world modeling of a manufacturing plant including the steps of specifying machines in the manufacturing plant and defining lots of parts manufactured in the plant, the improvement which comprises defining dynamic fabrication sequences as an ordered sequence of process steps and an ordered sequence of product flow, both of which change in time as a result of manufacturing plant conditions.
Specification