OPTEC - K.U.Leuven Center of Excellence: Optimization in Engineering

'Robust Optimal Control of Vessel Processing in Container Terminals'
Johannes Paefgen (ETH, Zurich)

Abstract:

With growth of maritime container traffic being a long-term trend, container terminal operators are continuously facing challenges in automation and optimization of logistic processes. Efficiency as well as reliability are necessary to handle an increasing cargo throughput and to prevail in competition. Improvement of planning methods plays a crucial role in this context. Container vessels reach the port on a weekly basis within an arrival window of given length, according to a fixed periodic schedule. Their processing requires an assignment of quay cranes and berth sections to vessels, and should be completed within a contractually agreed service time limit. This can be formulated as a stochastic dynamic resource allocation problem. In this thesis, an adaptive planning solution for vessel processing in a container terminal under uncertainty is developed. A Markov decision process model is proposed, and algorithms for derivation of its optimal control policy are given for different cost criteria. Furthermore, the resulting closed-loop system is analyzed with respect to robustness for non-modeled disturbances. Theoretical findings are supplemented with an implementation for testing purposes, for which computational results are provided.
The approach presented allows to solve realistically sized instances and yields a state-dependent control law in the form of a look-up table with regard to scheduled vessels. For non-modeled exceptions, an extension to this operational plan is given in terms of a prediction of resource availability over a finite horizon, leading to a subordinate model predictive controller.