Integrated optimization of storage location assignment and sequencing in multi-shuttle automated storage/retrieval systems under modified multi-command cycle

This article explores the integrated optimization of storage assignment and sequencing in multi-shuttle automated storage/retrieval systems (AS/RSs). Random storage policy and a modified multi-command cycle pattern are applied. An integer programming model aiming at minimizing the travel distance of storage/retrieval (S/R) machine is formulated. IBM ILOG CPLEX Optimization Studio (CPLEX) is applied to solve the model with optimal solutions for small-sized instances. A tabu search algorithm (TSA) is developed to deal with large-sized instances. Numerical experiments are conducted to assess the performance of TSA in terms of solution quality and computation efficiency. Instance parameters´ influences on TSA performance are also investigated.