Supervisory control of real-time discrete event systems using lattice theory

The behavior of timed DES can be described by a subset of the lattice formed by sequences of event occurrence times in much the same way that logical DES behaviors are described by a language of event sequences. This viewpoint allows questions of controllability for the class of timed DES modelled by timed event graphs to be treated in much the same manner as they are for untimed systems. Conditions for the controllability of a timed event graph can be expressed as inequations on the lattice. Extremal solutions to these inequations are found using methods developed for untimed DES