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.