Integration of Scheduling and Control in a Job Shop

In this work, we integrate scheduling and control algorithm in a job shop. An experimental system with centralized static scheduler, centralized on-line rescheduler, distributed real-time scheduler and distributed control architecture is also proposed herein. Three scheduling levels in our system are distinguished: static scheduling, rescheduling and real-time scheduling. The shifting bottleneck procedure is applied to static schedules and reschedules. Also, a dispatching rule MDT(Maximum Delivery Time) is proposed to be a real-time scheduling rule. How to design flexible manufacturing cells and develop cell controllers is also discussed. The Petri nets are used to design our flexible manufacturing cells. The PLC programming tool that follows the IEC1131-3 standard is then used to implement the cell controller in PLCs.