Optimization of the Bottleneck Caused by Stacker Cranes in Dynamic Hybrid Pallet Warehouses and Investigation of the Influence of the Input/Output Area on Performance

The need for ever-higher performance in pallet storage systems has led to the development of Dynamic Hybrid Pallet Warehouses (DHPW). DHPWs are created by either hybridizing a stacker crane-based warehouse with shuttles, or by hybridizing a shuttle-based warehouse with stacker cranes. One limiting factor in both categories is the bottleneck caused by having multiple stacker cranes in a single aisle. In this paper, we demonstrate that, by using the proper control algorithms, the stacker crane bottleneck can be alleviated in relation to the second DHPW category – almost to the point of reaching the performance that would be obtained by introducing an additional stacker crane. Finally, we illustrate how the design of the loop on the base tier has an increasing influence on the range of bottleneck improvement as the number of shuttles increases.