The Distributed Reconfigurable Factory Testbed (Drft): A Collaborative Cross University Manufacturing System Testbed.

Abstract

As a collaborative effort between the University of Michigan (UM), and Morgan State University (MSU) in Baltimore, a Distributed Reconfigurable Factory Testbed (DRFT) has been developed as part of the NSF Engineering Research Center (ERC) on Reconfigurable Manufacturing. The testbed combines hardware and simulation components at both universities operating under common control using secure channels over the Internet, and is designed in such a way as to ease the addition and modification of its various components The original UM RFT comprises 1) a serial-parallel manufacturing line, 2) a Virtual Factory software component, 3) factory-wide open software integration platform and data warehouse, 5) modular logic control developed at the cell level, and 6) a multi-teir networked control and diagnostic structure. To this system, the MSU portion was added comprising an Automated Storage and Retrieval system and a conveyor, where communication for monitoring and control was achieved via the OPC protocol operating through a Virtual Private Network (VPN).Students from both universities came together to plan the application and control structure for the combined system, giving students at MSU a chance to learn first-hand from the experiences of the students at UM. A demand-pull manufacturing application was built on the combined testbed where the MSU system functioned as a "Supply Cell" operating under control of the System Level Controller and the Software Infrastructure at UM. A robust handshaking communication protocol was developed to ensure the correct ordering of events in the presence of Internet communication delays and uncertainties. The inventory of the Supply Cell was tracked at UM where decisions about part availability to meet orders were made by the Software Infrastructure. Once parts were retrieved form the MSU Supply Cell, identical parts were introduced to the UM manufacturing line and virtual factory for machining and assembly. Web-based Human Machine Interfaces (HMI's) enabled students at both sites to monitor and control the operation of the entire system, and students could communicate and view both systems over a set of webcams. The combined testbed was successfully demonstrated at the ERCs annual NSF site visit in May 2005.

Can Based Fieldbus Experiments

“…Hong and Kim have developed network based intelligent motor control system using a fieldbus [8]. Also, in Reference [9] Luntz et al and in Reference [10] Bartz et al, described how internet-based experimentation concepts are adopted in manufacturing and control engineering curriculum. The concepts of fieldbus networks such as Devicenet are also introduced in PLC courses at several institutions [11,12].…”