An Optimization Model for Assembly Line Balancing Problem with Uncertain Cycle Time

Table 2

Notation used in mathematical models.

Symbol	Definition
Index
,	Task index
	Station index
	Number of tasks
	Operator’s skill level; 1, 2, and 3, respectively, indicate low, medium, and high skill
Parameter
	Cycle time
	Number of stations
	Maximum cycle time
	Minimum cycle time
	Time required to complete task when operator’s skill level is
	Precedence constraints between tasks and . indicates precedence constraints; otherwise, there is no precedence constraint.
	Spatial constraint between tasks and . indicates tasks must be assigned to the same station; otherwise, this is not required.
	Incompatible constraint between tasks and . indicates the tasks cannot be assigned to the same station; otherwise, they can.
	Number of operators with skill level
	Maximum number of tasks that can be accommodated on a station
Variable
	Binary variable. indicates that task is assigned to station .
	Binary variable. indicates that operators with skill level are assigned to task .
	Binary variable. indicates that station is enabled.