Information Technology for Manufacturing A Research Agenda (1995) / Chapter Skim
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5 Modeling and Simulation For the Virtual Factory
5 Modeling and Simulation For the Virtual Factory
Pages 109-118
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From page 109... ...
This approach requires a virtual factory to be a simulation that faithfully reflects that operation in all of the dimensions relevant to human managers, from the week-long and month-long time scales that characterize today's material requirements planning (MRP) and manufacturing resources planning (MAP-II)
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From page 110... ...
The most common user of information is a human being, who can be overwhelmed by either the number or the complexity of the user interfaces required to access or disseminate information. For example, senior factory managers are best able to comprehend results that are explicitly tied to financial metrics of performance; results tied to metrics relevant at lower levels in the hierarchy will be less helpful to them.
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From page 111... ...
(Factory floor communications are used, among other things, to keep track of equipment placement on the shop floor, a factor with a big impact on work flow; if a model does not reflect changes in equipment placement (which may change on a time scale of hours) , the model's output relevant to making work flow decisions may well be incorrect.)
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From page 112... ...
But the comprehensive integrated modeling of the manufacturing enterprise will provide new insight into the causes of and remedies for scheduling bottlenecks and new strategic options.2 An ultimate goal of the research agenda outlined here would be the creation of a demonstration platform that would compare the results of real factory operations with the results of simulated factory operations using information technology applications such as those discussed in this report. This demonstration platform would use a computer-based model of an existing factory and would compare its performance with that of a similarly equipped factory running the same product line, but using, for example, a new layout of equipment, a better scheduling system, a paperless product and process description, or fewer or more human operators.
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From page 113... ...
MODELING TECHNOLOGY A requirement for manufacturing models is that all levels of detail be internally consistent, since very small influences at a very local level may have a significant impact even at the highest factory level (e.g., if a piece of equipment goes down, the resulting schedule disruptions can shut down the entire factory)
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From page 114... ...
Reflecting factors such as resource availability, condition or repair status, and shop floor location, such models should interact with process and product models; indeed, at sufficiently high levels of abstraction, process model components may appear as components of a resource model. Careful configuration management of these models will provide an approach to alleviating the problem of validating models for a continually changing factory environment.
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From page 115... ...
· Developing new paradigms for understanding dynamic interactions among the different aspects and components of the manufacturing enterprise. A real factory consists of many interacting elements; thus, it is reasonable to expect a high-fidelity simulation to consist of many interacting elements (models)
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From page 116... ...
As a result, models have to be validated by being tested against understandable conditions, and in many cases, common sense must be used to judge if a model is "correct." Because models must be tested under stochastic factory conditions, which are hard to duplicate or emulate, outside the factory environment, an important area for research involves developing tools for use in both testing and validating model operation and behavior. Tools for automating sensitivity analysis in the testing of simulation models would help to overcome model validation problems inherent in a stochastic environment.
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From page 117... ...
Since manufacturing is such a varied and complex activity, and since the information exists over a very wide range (from high-level factory decision making to running a specific piece of equipment) , capturing the tacit knowledge of an experienced work force for later reuse represents a key challenge.
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From page 118... ...
The virtual factory simulation will require extensive parallel computation, but it will not be homogeneous. Therefore research is needed on new techniques to apply massive parallel processors to the simulation question.
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