Effects of Arrival Uncertainty on Solver Performance in Dynamic Stacking Problems
S. Raggl, A. Beham, S. Wagner, M. Affenzeller - Effects of Arrival Uncertainty on Solver Performance in Dynamic Stacking Problems - Proceedings of the 32nd European Modeling & Simulation Symposium (EMSS 2020), Online, Greece, 2020, pp. 193-200
In this paper, we present a dynamic stacking problem with uncertainty. We developed a simulation environment, an optimizer for solving it, and performance measures to determine the success of the optimizer. The problem requires handling
incoming blocks, stacking them efficiently, and meeting deadlines for delivery, while not knowing exactly when blocks will
arrive or when they will be ready for delivery.
The optimizer models the problem as a dynamic Block Relocation Problem and solves it using a branch&bound based
heuristic. The simulation and optimizer run concurrently and the distribution of random variables is not disclosed to the
solver and must, therefore, be estimated.
We study the influence of uncertainty on the solver and show that the degree of uncertainty has a significant impact on the
performance of the overall system. We also experiment with different measures to estimate uncertain arrival times and show
that the choice of measure is important for achieving good performance.