Application of Effective Transition Covers on Deadlock Control of Unsignalized Intersection Systems

Vehicle congestion or collision can easily happen at unsignalized intersections if there are no appropriate control policies. In this paper, we mainly focus on special congestions due to vehicle circular waits, i.e., deadlocks. Based on Petri nets, a small-size deadlock prevention policy is designed to ensure that vehicles can pass smoothly and efficiently through any unsignalized intersection. Firstly, the two-way four-lane unsignalized intersection is discretized and the system is modeled and called TWFLUI net. Secondly, an effective transition cover of the net is computed and then a small-sized Petri net controller based on the effective transition cover is synthesized. Finally, the liveness of the proposed controller is proved, which shows that the smooth traffic at the unsignalized intersection can be guaranteed. In other words, the effectiveness of the deadlock prevention policy is shown. Meanwhile, its advantage is also illustrated by comparing with the methods in literature.