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

A dual command (DC) cycle “dynamic sequencing” method in unit-load multiple-rack AS/RS system under time-of-use (TOU) electricity tariffs are applied in this paper. To make a type of energy efficient model, over cost of on-peak period electricity consumption, penalty cost for over power consumption, bounds on 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 of 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 simulation annealing (SA) algorithm is developed in addition to certify the outcome gained. For supplementary confirmation, we comparing the total cost of our model with the single tariff model and also doing a sensitivity analysis for 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 number of required storage/retrieval orders are suggested to display the function of the proposed procedure. Our outcomes verified that GA was able to obtain well and closer optimal solutions and the TOU tariffs model get minimum total cost.