Aggregate Control of Production Systems

Abstract

In the design of production systems one is often interested in capacity oriented, rather than detailed performance objectives. An example of a detailed performance objective is the timely delivery of specific product types. Capacity oriented objectives, also called “aggregate” objectives, are objectives with respect to the global behavior of the system, expressed in some aggregate product unit. Examples of such capacity oriented objectives are the realization of a certain production volume (expressed as “products” per year), or the achievement of short average lead times and little work-in-process. It is the task of production control to realize both a good detailed and a good capacity performance. Consider the case of a manufacturer of coin validators (a coin validator is the tool that evaluates coins in coffee machines for instance). This manufacturer is designing a new production line. He has a good idea about what the market will be: worldwide he can sell about 550,000 coin validators a year. The production line has to be able to manufacture this amount of products. The manufacturer does not know in advance to what countries he will sell nor in what quantities. This creates a problem, because different countries demand different coin validators, with different manufacturing characteristics. He has to make sure that, whatever the eventual required product mix will be, he can fulfill this demand (at reasonable costs).