Effect of upstream re-sequencing in controlling cycle time performance of batch processors

• Dynamic control of batch processor using near-future arrival information.
• Decision on waiting for future arrival or start a partial batch.
• Consider re-sequencing of jobs upstream while waiting to improve cycle time.
• New look-ahead batch control strategy using a rolling horizon decision making.
• Application in wafer fabrication and other systems with serial and batch processing.

This paper demonstrates the effect of incorporating upstream sequence decisions in the cycle time control of batch processors. The focus is on dynamic control of a batch processor where near-future arrival information is available by predicting the process times on its upstream processor. In a particular decision point, the dynamic control task is to decide whether to start the batch process with one of the available product types immediately or to wait for future arrivals coming from the upstream processor. While considering a wait decision alternative, a re-sequencing approach at the upstream processor is proposed to shorten the arrival time of the desired product. Combining this architecture with a rolling horizon decision making, we propose a new look-ahead batch control strategy. A serial-batch processor system that is typical in wafer fabrication is modeled to demonstrate the approach. Simulation based benchmarking shows promising results.