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.
Instances
IGA
Two-stage-1
Two-stage-2
Distance
Distance
(%)
Distance
(%)
Small-scale
20
10
16
3
20
13.75
13
25
25
81.82
30
30
118.18
20
10
16
3
100
86
86
125
125
45.35
131
131
52.33
20
10
16
3
500
528
528
646
646
22.35
769
769
45.64
20
10
16
3
1000
1120
1120
1288
1288
15.00
1506
1506
34.46
20
10
16
3
1500
1713
1713
1938
1938
13.13
2301
2301
34.33
Medium-scale
250
200
240
7
20
49.50
49
95.50
95
92.93
84
84
69.70
250
200
240
7
100
421
421
624
624
48.22
593
593
40.86
250
200
240
7
500
3941
3941
4839
4839
22.79
4546
4546
15.35
250
200
240
7
1000
9105
9105
10188
10188
11.89
9962
9962
9.41
250
200
240
7
1500
14484
14484
15729
15729
8.60
15482
15482
6.89
Large-scale
500
400
448
9
20
114.50
114
206.50
206
80.35
130
130
13.54
500
400
448
9
100
1013
1013
1589
1589
56.86
1149
1149
13.43
500
400
448
9
500
11155
11155
12881
12881
15.47
12269
12269
9.99
500
400
448
9
1000
27197
27197
30207
30207
11.07
29546
29546
8.64
500
400
448
9
1500
44105
44105
47736
47736
8.23
47041
47041
6.66
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.