Betriebspunktuntersuchung des Lagerfüllgrads eines doppeltiefen automatischen Hochregallagers

Abstract

For the planning and efficient operation of a double-deep automatic storage and retrieval system (AS/RS), the determination of a good operating point regarding the stock filling level is a decisive task. If the stock filling level of the AS/RS is low, the system still offers capacities for the storage of addi-tional storage units, and relocation operations due to blocking storage units can be prevented. If, how-ever, the stock filling level of the AS/RS is very high, the number of operations of the storage and retriev-al machine increases due to relocation operations, which leads to longer single command and double command cycle times, which make the storage of goods more expensive. This paper presents an ana-lytical model that can be used to determine the best operating point for the stock filling level of an AS/RS, depending on the travel times and space uti-lisation level of an AS/RS. The analytical model is based on an optimization problem whose utility function evaluates the warehouse filling level posi-tively and the expected relocation time per retrieval command cycle negatively. This model is based on a travel time model, which shows that a variance re-duction strategy is superior to a random storage as-signment strategy and can reduce the travel times. Beyond that it is possible to show that the minimal variance strategy can be realised due to dual com-mand cycles.