Computer Simulation of Demand Controlled Production

Abstract

This paper examines the application of advanced control techniques, originating from the process industries to supply chain management (SCM) problems arising in semiconductor manufacturing. The main objective of this work is to demonstrate the usefulness of the applied model-based, multi-layer controller/optimiser structure. The tactical local decision policy is an integral part of a comprehensive hierarchical decision framework, achieving operational excellence. A flow network analogy is used to describe the dynamics of the supply chain. Compared to traditional flow control problems, challenges of SCM in semiconductor manufacturing result from high stochasticity and nonlinearity, associated with throughput times, yields and customer demands. (Lehőcz and Csukás, 2005; Lehőcz, 2007) The system’s elements are dependent on each other. They mainly depend on their neighbours, but the effect of a local decision expands to the whole system, stepwise. The type, strategy and parameters of the local controllers are varied, and defined on-line by a genetic algorithm during the optimization process. The ’’achieving operational excellence’’can be quantified by a scalar performance (cost) index which should be minimized. In this case this index is the operation cost.