Planning and Control Concepts for Material Handling Systems

The purpose of this research is the development of new concepts for different planning and control problems within material handling centres, like warehouses and container terminals. Problems discussed, are, for example: (i) the determination of the number of vehicles required to transport all loads in time (ii) scheduling of storage and retrieval requests. Techniques from Operations Research are used to model and solve above mentioned problems.

Firstly, a polynomial time algorithm (minimum flow algorithm) is developed to solve the problem of the determination of the minimum number of vehicles to transport all loads at known time instants. An extension of this problem is the determination of the minimum number of vehicles required if every job has a time window. In this case, a release time and a due time are given for every job. This problem can be formulated as an integer linear programming model and a set partitioning model. A dynamic programming model is developed to solve the scheduling of retrieval and storage requests for a storage and retrieval machine working in multiple parallel aisles.

All developed methods will be applied within a semi-automated container terminal. For the internal transportation of containers from ship to stack (storage) and vice versa and for inter terminal transport Automated Guided Vehicles (AGVs) will be used. Also stacking will be done in an automatic way by Automated Stacking Cranes (ASCs). Simulation studies are performed to test the methods developed.