On-line reconfiguration to enhance the routing flexibility of complex automated material handling operations

Traditionally, automated material handling systems are not designed to be reconfigurable and changes to layouts and material flow directions often require significant downtime for physical modifications and reprogramming to be made. As a consequence of global trends towards mass customisation, higher mix and lower volume production, shorter product life cycle, shorter lead-time, increasing velocity of goods across supply chains, and the increasing use of industrial information technology (IT), modern automated material handling systems (AMHS) should be designed with reconfiguration features to maximise utilisation and to enhance its flexibility. This paper focuses on how on-line reconfiguration of complex AMHS can be technically achieved (from both hardware and software considerations), which enables operational routing flexibility as well as recovery routing flexibility when faults occur. Three common “design for on-line reconfiguration” areas are first proposed, namely, resource availability of the entire AMHS or its components, reversible direction of an individual or a group of conveyors, and expandable operating range (or domain) of common-aisle transporters. Design considerations and implementation techniques for a class of reconfigurable AMHS are then discussed. Finally, we illustrate how on-line reconfiguration was implemented for a large-scale complex automated warehouse with several AMHS.