Green and lean control of cyclic pallet systems

Reduction of energy consumed by a manufacturing system to turn raw parts to finished products is a big step towards the green and lean production. In this study the energy efficiency of a one-loop pallet system, a main tool to handle and locate various part types in a cyclic production line, is investigated. The main goal is to obtain the minimal energy consumption in the pallet system drive unit through an optimally controlled and coordinated motion of pallets. To achieve the mentioned goal, first the mean value of the pallet system energy consumption is mathematically modeled. Later, this energy model is utilized as an objective function within an optimization model including constraints on system crucial properties such as cyclic and dynamic behavior, queueing policy, and buffer size. The solution of the optimization problem gives the optimal values of the system control variables, namely, number of pallets and conveyor velocity. To demonstrate the application of this optimization model in practice, three case studies are introduced. The results of these studies show that a significant amount of the energy consumption may be saved by applying the suggested green control.