|Move Blocking Strategy Applied to Re-entrant Manufacturing Line Scheduling
Tae Y. Jung, Hong Jang, and Jay H. Lee*
International Journal of Control, Automation, and Systems, vol. 13, no. 2, pp.410-418, 2015
Abstract : Model predictive control (MPC)-based approach to fabwide scheduling has been suggested to solve constraint-aware production optimization and in-process inventory level control simultaneously at each scheduling instance. However, application of this approach to real fab suffers from computational difficulties brought by the need to solve a huge optimization problem on-line as real fab scheduling problems are characterized by long cycle times, multiple product types, hundreds of ma-chines/processing steps and re-entrant product flows. This study explores the use of an offset-blocking strategy combined with a modified recursive least square (RLS) estimation in the fab-wide scheduler, in order to alleviate the difficulty. The strategy is tested on a modified version of published case study called Intel Mini-Fab (IMF) problem. Despite its simplicity, the blocking strategy showed excellent performance in the face of realistic demand changes and plant/model mismatch.
Fab-wide scheduling, model predictive control (MPC), move blocking strategy, recursive least square estimation, re-entrant manufacturing line.
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