Research Article

Joint Optimization of Item and Pod Storage Assignment Problems with Picking Aisles’ Workload Balance in Robotic Mobile Fulfillment Systems

Table 2

The notations used in the J-IPSAP.

ParametersMeaningValue

Set of items
Set of pods
Set of pod layers
Set of orders
Set of pod locations
Set of picking aisles ()
The value of the threshold weight coefficient
The number of orders to purchase item
The number of orders to purchase both items and
The purchase frequency of item  = 
If order contains item , it equals 1, otherwise, it equals 0
If location is in aisle , it equals 1, otherwise, it equals 0
The number of storage locations of item
The relevance coefficient of items and , when  = ,  = 0, otherwise  = /
The distance from location to the picking station