5.2. Sequencing and routingThe sequ

5.2. Sequencing and routing
The sequencing and routing decision in order picking operations determines the best sequence and route of locations for picking and/or storing a given set of items. The objective is typically to minimize the total material handling cost. This problem
is a warehouse-specific Traveling Salesman Problem(TSP), where the picking/storing location of an item is given. The problem where there are several candidate locations for the retrieval or storage of an item is more complex and few research results are available, although it is often found in practice. The TSP in the warehouse is special because of the aisle structure of the possible travel paths. The published
research focuses on four classes of warehouse systems, i.e.,conventional multi-parallel-aisle systems,
man-on-board AS/RS systems, unit-load AS/RS
systems, and carousel systems.