Smart deadlock prevention policy for flexible manufacturing systems using Petri nets

Deadlocks are a highly undesired situation in automated production systems including flexible manufacturing systems. Based on a Petri net formalism, a novel deadlock prevention policy is proposed for a class of Petri nets, S³PR, by using an MIP-based deadlock detection method and elementary siphons of Petri nets. Deadlock prevention is achieved by synthesising a set of monitors that are added to the plant net model. The concept of dominated transitions is proposed, to which the output arcs of the monitors are led. The monitors are computed according to a set of elementary siphons in a plant net model, which is found by using an established algorithm in the literature. When compared with the existing policies, the proposed method leads to a liveness-enforcing Petri net supervisor with a small number of monitors but more permissive behaviour. Examples are used to demonstrate the proposed method.