Throughput optimization of automated flats sorting machines

Abstract: Large letters, journals, magazines, plastic wrapped mail items of A4 size are called flats. In order to be able to handle the large volumes of flats that have to be processed state-of-the-art post sorting centers are equipped with dedicated flats sorting machines. The throughput of a flats sorting machine is crucial when dealing with a continually increasing number of items to be sorted in a certain time. But, the throughput is limited by the mechanical constraints. We propose to optimize the efficiency of this sorting system by making several design changes and implementing advanced model-based control methods such as optimal control and model predictive control. In this paper we determine an event-based model of the flats sorting system. The considered control methods are compared for several scenarios. Results indicate that using the proposed approaches the throughput can be increased with up to 52.62%, the computation of the optimal velocity being performed in real-time. 1