Research Article

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

Table 5

Comparative results among the IGA, Two-stage-1, and Two-stage-2.

InstancesIGATwo-stage-1Two-stage-2
DistanceDistance(%)Distance(%)

Small-scale20101632013.7513252581.823030118.18
2010163100868612512545.3513113152.33
201016350052852864664622.3576976945.64
20101631000112011201288128815.001506150634.46
20101631500171317131938193813.132301230134.33

Medium-scale25020024072049.504995.509592.93848469.70
250200240710042142162462448.2259359340.86
2502002407500394139414839483922.794546454615.35
2502002407100091059105101881018811.89996299629.41
25020024071500144841448415729157298.6015482154826.89

Large-scale500400448920114.50114206.5020680.3513013013.54
5004004489100101310131589158956.861149114913.43
50040044895001115511155128811288115.4712269122699.99
500400448910002719727197302073020711.0729546295468.64
50040044891500441054410547736477368.2347041470416.66

Note. ; Distance: the fitness function value without considering the penalty cost. The bold values in Table 5 indicate the minimum Gap of two-stage-1, two-stage-2, and IGA, respectively.