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.

Parameters	Meaning	Value
	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