Intelligent material handling: Development and implementation of a matrix-based discrete-event controller

A supervisory controller for discrete-event (DE) systems is presented that uses a novel matrix formulation. This matrix formulation makes it direct to write down the DE controller from standard manufacturing tools such as the bill of materials or the assembly tree. The matrices also make it straight forward to actually implement the DE controller on a manufacturing workcell for sequencing the jobs and assigning the resources. It is shown that the DE controller equations plus the Petri net marking transition equation toge ther provide a complete dynamical description of a DE system. This means th at a computer simulation can be performed to check the DE performance of th e controller before it is implemented. In this paper, we implement the DE c ontroller con an actual three-robot intelligent material handling cell at t he Automation and Robotics Research Institute, University of Texas at Arlin gton. Then, we show that the actual implementation and the simulated system give commensurate results. The versatility of the system developed with th is DE controller permits implementing different methodologies for conflict resolution, as well as optimization of the resource assignment and part thr oughput. Technical information given includes the development of the contro ller in Lab-VIEW and its simulation using MATLAB.