Deadlock avoidance in sequential resource allocation systems with multiple resource acquisitions and flexible routings

This paper considers the deadlock avoidance problem for the class of conjunctive / disjunctive (sequential) resource allocation systems (C/D-RAS), which allows for multiple resource acquisitions and flexible routings. A new siphon-based characterization of deadlocks arising in C/D-RAS is developed, and subsequently, this characterization facilitates the development of a polynomial-complexity deadlock avoidance policy (DAP) that is appropriate for the considered RAS class. The developed policy can be perceived as a generalization of RUN DAP, originally developed for sequential RAS with unit resource allocations and no routing flexibility. The last part of the paper investigates the flexibility enhancement of the proposed policy implementations through (i) the pertinent exploitation of the policy parameterization, and (ii) the systematic relaxation of the policy-imposed constraints through siphon-based structural analysis of the underlying Petri-net system model. The paper results are demonstrated through examples coming from the application area of flexibly automated production systems.