Sustainable and robust control of cyclic pallet systems

A proper control of a system to get a desired function and increase the system lifetime is a crucial step towards the sustainable paradigm. In this paper, such a control is designed for a cyclic pallet system to achieve a minimal force on its drive unit, meet safety conditions on the system chain tension force and the momentum of pallets, and fulfill the desired production rate. The optimal values of the control parameters, namely number of pallets and conveyor velocity, are obtained through solving a linear optimization model. The objective function in the model defines the average force on the drive unit in a cycle production. In addition, the related constraints characterize the pallet system properties such as cyclic and dynamic behavior, buffer size, constant work in process, and safety specifications. The robustness of the optimal control is analyzed, using a worst but safe control strategy. The optimal control and the robustness analysis are applied to some case studies, and the results are evaluated and discussed.