Matrix controller design and deadlock analysis of automated manufacturing systems. Part 2: Deadlock avoidance policy

A matrix framework is offered that permits direct, fast design and reconfig ures the ride-based controllers for automated manufacturing systems. The co ntroller design is based on standard manufacturing techniques such as the b ill of materials, task sequencing matrix, and resource requirement matrix t hat give the matrix equations. The result is a multiloop discrete event con troller with outer loops for dispatching of shared resources. The equations of the closed-loop manufacturing system can be used to derive a Petri net for rigorous performance analysis. Combining the matrix controller state eq uation and the well-known Petri nets marking transition equation yields a c omplete dynamical description of a discrete event system. The matrix formul ation allows a rigorous analysis of deadlock in terms of circular blockings , siphons, and the numbers of resources available. This allows efficient di spatching and routeing with deadlock avoidance. The matrix controller also allows both nonlinear activity level algorithms and logical discrete-event supervisory algorithms. Such a hybrid controller would potentially allow th e optimisation of shared resource assignment and job sequencing between mac hines with fast and precise operation of each individual machine. A multipl e-part-path re-entrant job shop is used to illustrate the concepts introduc ed.