Dynamic Control of a Flow-Rack Automated Storage and Retrival System

Abstract

In this paper we propose a control scheme based on coloured Petri net (CPN) for a
flow-rack automated storage and retrieval system. The AS/RS is modelled using Coloured Petri
nets, the developed model has been used to capture and provide the rack state. We introduce in the
control system an optimization module as a decision process which performs a real-time
optimization working on a discrete events time scale. The objective is to find bin locations for the
retrieval requests by minimizing the total number of retrieval cycles for a batch of requests and
thereby increase the system throughput. By solving the optimization model, the proposed method
gives according to customers request and the rack state, the best bin locations for retrieval, i.e.
allowing at the same time to satisfy the customers request and carrying out the minimum of
retrieval cycles.