Time-optimal control for re-entrant semiconductor fabrication lines

This paper addresses the problem of determining time-optimal resource allocation schedules for re-entrant semiconductor manufacturing lines. More specifically, a solution is presented for the problem of determining a product (start) release schedule and machine work schedules such that the buffer levels are driven from a given initial state to a final desired state in minimum time. The development is based upon widely used flow models. Algorithms are presented for determining the optimal reachability time and an admissible time-optimal scheduling policy