Simulation modeling of a dynamic job shop rescheduling with machine availability constraints

In this paper we study dynamic job shop rescheduling where machine workstations are not always available due to breakdown or preventative maintenance. A visual interactive simulation model using the AWESIM discrete event modeling tools was constructed to show how the state dependent rescheduling technology is used. Heuristics have been refined in order to include job shop state variable information. It was found that the job shop rescheduling problem can be simplified by understanding the state of the entire job shop and using this state knowledge to sequence jobs in work station queues. We develop the PMBD heuristic that relies only on predicted downstream machine failure times and we compare it with other conventional heuristics that are modified to use job shop state information.