In order to efficiently use an automated shelf system the stacker cranes must perform all storage and retrieval operations as good as possible''. possible objectives are, e.g., minimizing the total distance of empty moves or the weighted sum of all waiting times. Due to non-predictable response times with respect to incoming orders, order completion or cancellation a real-time control system is needed, which is able to produce good solutions (i.e., an assignment of a transportation task to the stacker crane) in short time (sometimes less than a second).

In cooperation with Siemens-Nixdorf AG, mathematical models for the optimal routing of stacker cranes (asymmetric travelling salesman problems with additional side-contraints like precedences, time windows) have been developed. These are planned to be applied in the distribution center of our other industrial partner Herlitz PBS AG.

The real-time compliance of Various control methods will be evaluated in a simulation environment. Our goal is to develop a library of optimization procedures, suitable for various types of automated shelf systems.