Design of Optimal Petri Net Supervisors for Flexible Manufacturing Systems via Weighted Inhibitor Arcs


Cong X., Gu C., UZAM M. , Chen Y., Al-Ahmari A. M. , Wu N., ...More

ASIAN JOURNAL OF CONTROL, vol.20, no.1, pp.511-530, 2018 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 20 Issue: 1
  • Publication Date: 2018
  • Doi Number: 10.1002/asjc.1583
  • Title of Journal : ASIAN JOURNAL OF CONTROL
  • Page Numbers: pp.511-530
  • Keywords: Deadlock prevention, flexible manufacturing system, observer place, Petri net, supervisory control, weighted inhibitor arc, DEADLOCK PREVENTION POLICY, LIVENESS-ENFORCING SUPERVISORS, DEPENDENT SIPHONS, ALGEBRAIC SYNTHESIS, ELEMENTARY SIPHONS, AVOIDANCE, CONTROLLABILITY, CONTROLLERS, FMS, CONSTRAINTS

Abstract

This paper develops an approach to the design of an optimal Petri net supervisor that enforces liveness to flexible manufacturing systems. The supervisor contains a set of observer places with weighted inhibitor arcs. An observer place with a weighted inhibitor arc is used to forbid a net from yielding an illegal marking by inhibiting the firing of a transition at a marking while ensuring that all legal markings are preserved. A marking reduction technique is presented to decrease the number of considered markings, which can dramatically lower the computational burden of the proposed approach. An integer linear program is presented to simplify the supervisory structure by minimizing the number of observer places. Finally, several examples are used to shed light on the proposed approach which can lead to an optimal supervisor for the net models that cannot be optimally controlled via pure Petri net supervisors.