In this paper, we develop a new mathematical model for a cyclic multiple-part type three-machine robotic cell problem with assumption of S 6 robot movement policy that minimises the cycle time. The developed model is based on Petri nets and provides a new method to calculate cycle times by considering waiting times. It was proved that calculating cycle time under S 6 policy is unary NPcomplete. Obtaining an optimal solution for this type of complex, large-sized problem in reasonable computational time by using traditional approaches and optimisation tools is extremely difficult. In this paper we implement the particle swarm optimisation (PSO) algorithm for solving the problem. To validate the developed model and solution algorithm, various test problems are examined.
