The container retrieval problem (CRP) is an important issue to achieve high yard operational efficiency in a container terminal system. The CRP aims to find an optimal sequence of operations for the crane to retrieve all the containers from the bay according to a predefined order. An optimal sequence of operations is obtained by either reducing the number of container relocations or reducing the total travel distance performed by the crane, i.e., crane's trajectory. In contrast to previous studies discussed in the literature, in this study, the optimization goal is to minimize the trajectory undertaken by crane. In this regard, this paper proposes two exact optimization algorithms based on Dijkstra's algorithm and A* search algorithm frameworks. The latter includes proposal of an intelligent strategy to explore the most promising nodes in the search tree. The experimental results show that the proposed algorithms achieve an optimal solution in a shorter computation time when applied to realistic scenarios.
['Andresson da Silva Firmino', 'Ricardo M. A. Silva', 'Valéria Cesário Times']
An exact approach for the container retrieval problem to reduce crane's trajectory