TY - JOUR
T1 - Liveness enforcing supervisory policies tolerant to controllability failures for discrete-event systems modeled by Petri Nets
AU - Raman, Arun
AU - Sreenivas, Ramavarapu S.
N1 - Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2021/3
Y1 - 2021/3
N2 - A Discrete Event System (DES) modeled by a Petri Net (PN) is live if it is possible to fire any transition, although not necessarily immediately, from any marking that is reachable from the initial marking. A Liveness Enforcing Supervisory Policy (LESP) for a PN enforces liveness by preventing the firing of a subset of transitions called the controllable transitions, which correspond to the preventable events in a DES. In this paper, we consider the existence and synthesis of LESPs for arbitrary PNs in the presence of faults, where a subset of controllable transitions become temporarily uncontrollable, for a finite number of event occurrences. Following the formal specification of the fault model, we present a necessary and sufficient condition for the existence of Fault-Tolerant LESPs (FT-LESPs) for arbitrary PNs. We show that, even when an LESP is given, the existence of an FT-LESP for an arbitrary PN is undecidable. We then identify a class of PNs for which the existence of FT-LESPs is decidable. We conclude with some suggestions for future research.
AB - A Discrete Event System (DES) modeled by a Petri Net (PN) is live if it is possible to fire any transition, although not necessarily immediately, from any marking that is reachable from the initial marking. A Liveness Enforcing Supervisory Policy (LESP) for a PN enforces liveness by preventing the firing of a subset of transitions called the controllable transitions, which correspond to the preventable events in a DES. In this paper, we consider the existence and synthesis of LESPs for arbitrary PNs in the presence of faults, where a subset of controllable transitions become temporarily uncontrollable, for a finite number of event occurrences. Following the formal specification of the fault model, we present a necessary and sufficient condition for the existence of Fault-Tolerant LESPs (FT-LESPs) for arbitrary PNs. We show that, even when an LESP is given, the existence of an FT-LESP for an arbitrary PN is undecidable. We then identify a class of PNs for which the existence of FT-LESPs is decidable. We conclude with some suggestions for future research.
KW - Deadlock
KW - Discrete-event dynamic systems
KW - Discrete-event systems
KW - Fault-tolerant systems
KW - Petri-Nets
KW - Supervisory control
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U2 - 10.1016/j.automatica.2020.109430
DO - 10.1016/j.automatica.2020.109430
M3 - Article
AN - SCOPUS:85099179998
SN - 0005-1098
VL - 125
JO - Automatica
JF - Automatica
M1 - 109430
ER -