Scheduling has been a complex problem across most industries, especially in the
context of online scheduling, where information availability can often be limited or
uncertain. Companies are therefore, tasked with making appropriate scheduling
decisions to enhance their business value. This thesis begins with evaluating the
performance of widely employed scheduling methods, then examine whether
production aggregation could improve efficiency through iterative simulations. The
results of the experiments suggest that production aggregations require more
holding costs and do not reduce the machine changeover time as we expected.
Nonetheless, the overall reward does not show any sign of differences compared to
the priority heuristic. Beyond analyzing the scheduling method, we created DRL
environments based on the heuristics and trained them with DQN and PPO.
Notably, DQN yielded significant performance improvements, especially in the
production aggregation environment. Unfortunately, the PPO algorithm does not
properly converge due to its sensitive nature in model design and hyperparameter
tuning. In conclusion, this thesis provides valuable insights on online scheduling,
stochastic manufacturing systems, production aggregation, and shed the light of
primary application of DRL in online scheduling.
«
Scheduling has been a complex problem across most industries, especially in the
context of online scheduling, where information availability can often be limited or
uncertain. Companies are therefore, tasked with making appropriate scheduling
decisions to enhance their business value. This thesis begins with evaluating the
performance of widely employed scheduling methods, then examine whether
production aggregation could improve efficiency through iterative simulations. The
results...
»