This article proposes an iterative deadlock resolution method for flexible manufacturing systems modeled with G -systems.To design a non-blocking controlled system with maximally permissive behavior in a G -system ( GS ), a reachability graph-based analysis technology is utilized.Since the reachability graph of a large-scale GS easily becomes unmanageable, an optimal non-blocking supervisor becomes a challenging problem in a GS.
To facilitate this problem, the Divide-and-Conquer approach is a good choice for complex G -systems.First, an uncontrolled GS resolves into a number of associated subnets.Then, every subnet suffering from deadlocks is utilized Refrigerator to design the liveness-enforcing supervisor for the original GS.
Thus, additional monitors can be obtained if the liveness of all subnets is achieved.Subsequently, a partially controlled GS is derived by including all monitors within the GS , and its liveness can be ensured by designing a new set of Island Hood monitors.Consequently, a non-blocking GS is derived.
The major advantage of the proposed method is that a non-blocking supervisor with near-optimal behavioral permissiveness can be obtained in general.Finally, a typical GS example popularly studied in the literature is applied to demonstrate the validity and the availability of the method in this article.