Consider a miniload AS/RS used for end-of-aisle order picking. It is assumed that the P/D station is located at the lower lefthand corner of the rack and that there are two pick positions. Consider a single-aisle system with one picker. Under the current mode of operation, the containers within a given order are retrieved on a closest-container-first basis. That is, the container closest to the P/D station (in travel time) is retrieved first, and so on. Ties are broken randomly. (Recall that no other container can be retrieved before all the containers needed for filling the current order have been retrieved.) Furthermore, the parts handled by the system are small enough that multiple stock-keeping units (SKUs, or part numbers) can be stored in each container (or tray).

Currently, the system is unable to meet the required throughput level. Moreover, it has been established that

(i) It is impossible to further reduce the mean and/or variance of the time required to pick a SKU.

(ii) It is impossible to further increase the travel velocity (or acceleration and deceleration)

of the S/R machine (in either direction, horizontal or vertical). Likewise, the container handling time (or pickup/deposit time) is fixed.

(iii) The space requirement is expected to remain at its present level. Therefore, the rack size may not be reduced.

(iv) Management is unwilling to purchase another miniload aisle. However, they are willing to support reasonable modification(s) to the current system.

Given the above situation, how would you attempt to improve the throughput performance of the system? Explain and discuss at least three conceptually different alternatives. For each alternative, you must carefully argue why, how, and under what conditions you would expect the throughput to show a reasonable improvement.

The economic comparison of the alternatives and the relative amount of improvement offered by each alternative are not within the scope of the question.

However, your suggestions must be realistic and reasonable from an implementation standpoint.