Performance Evaluation of Full Turnover-based Policy in the Flow-rack AS/RS

In a flow-rack AS/RS, unit-loads to be stored slide from the storage face to the retrieval face driven by the gravity, which lets stored unit-loads follow the first-in-first-out rule in each bin. Consequently, a requested unit-load might be blocked by blocking unit-loads stored in front of it. Blocking unit-loads require extra cost to be removed and restored before retrieving requested ones. Full turnover-based (FTB) storage policy can be employed in flow-rack AS/RS, in which each bin contains the same type of unit-loads to ensure the avoidance of blocking unit-loads when systems request a unit-load. In this paper, the performance of FTB policy is evaluated for the flow-rack AS/RS, which is compared to the in-deep storage policy. Because in-deep storage policy takes a lot of time to deal with blocking unit-loads, we can see whether FTB policy without blocking unit-loads performs better than in-deep storage policy with the same external conditions.