A time fidelity control foundation for hierarchical discrete-event systems

In the existing paradigm of formal languages and finite automata, the hierarchical control setup for untimed discrete-event systems (untimed DES´s) is a standard high-level command and low-level control structure, and timed DES´s (TDES´s) can be modeled by a class of automata called timed transition graphs (TTG´s) incorporated with time fidelity. In this paper, using the same hierarchical control setup, with the TDES at the low level modeled by a Moore TTG with time fidelity, supporting concepts are proposed for a timed version of the concept of output-control consistency for hierarchical control. Importantly, this new timed consistency concept also preserves the time fidelity of the resultant system model at the high level, and lays a time fidelity foundation for extending the consistency of hierarchical control in untimed DES´s to TDES´s.