Energy-conscious dynamic sequencing method for dual command cycle unit-load multiple-rack automated storage and retrieval systems

Abstract

A Dual Command (DC) cycle "dynamic sequencing" method in unit-load multiple-rack AS/RS system under Time-Of-Use (TOU) electricity tariffs is applied in this paper. To make a type of energy-efficient model, overconsumption cost of on-peak period electricity, penalty cost of overconsumption of power, bounds on the total consumed energy, and accessible times of all facilities are considered in the model. Moreover, a Genetic Algorithm (GA) is developed to achieve a near-optimum solution to the suggested energy-based mathematical model with the objective of minimizing the total cost of the AS/RS system under TOU tariffs. Considering that no benchmark is obtainable in the literature, a Simulated Annealing (SA) algorithm is developed to certify the outcome gained. For supplementary confirmation, we compare the total cost of our model with that of single-tariff model and also conduct sensitivity analysis of the allowable amount of power consumption. The system throughput, in terms of time and cost, is calculated for the model too. In the last part, sixteen numerical examples with different numbers of required storage/retrieval orders are suggested to display the function of the proposed procedure. Our outcomes verified that GA is able to obtain favorable and closer optimal solutions and the TOU tariffs model get the minimum total cost.