论文简介 |
This paper presents a liveness analysis method for sequential automated manufacturing systems (AMSs), which can be modeled by a class of Petri nets named systems of sequential systems with shared resources (S⁴PR). We show that deadlocks in S⁴PR can be characterized by the saturation of its structural object named a perfect activity circuit (PA-circuits). Thus, S⁴PR is live if and only if no PA-circuits in it is saturated at all reachable states. A PA-circuits of an S⁴PR may not be saturated at any state; hence, we propose an integer linear program (ILP) to determine whether a PA-circuits can be saturated or not. Then an algorithm is proposed to compute the set of PA-circuits that may be saturated. This presented method nontrivially generalizes deadlock characterization and liveness condition of ordinary Petri nets to a broader class of nonordinary ones. |