Abstract

Eliminating deadlocks and reserving maximal permissiveness together is an important and hot issue for all kinds of flexible manufacturing systems. Many experts are making much effort to obtain optimal control algorithms. However, most researchers cannot obtain the real optimal controllers even though their policy is maximally permissive, especially for special S4PR (Systems of Sequential Systems with Shared Resources) systems. Based on this reason, this paper tries to propose a novel recovery policy to recover systems’ all states based on control transitions (CT). Therefore, the system can hold the real maximal permissive states. Especially, we propose the concept of the shortest path selected marking (SPSM) so that we can hence obtain the recovery transition. Furthermore, our proposed concept avoids solving integer linear programming problems (ILPP) based on our algorithm method. Moreover, three examples of S4PR Petri net models (PNM) with deadlocks are illustrated in our proposed algorithm. Experimental data shows that our policy can not only prevent the deadlocks but reserve all initial markings in S4PR. Please notice that this proposed recovery policy seems the first one applied for S4PR by using control transitions and still obtaining the best permissiveness whatever their algorithms among existing literature belong to use control places or control transitions.

Highlights

  • Nowadays is an era of digitization, mechanization, diversification, and artificial intelligence

  • If we want to design a control transition (CT) denoted ttcc in this deadlock Petri net models (PNM) and push the deadlock marking Marking 12 (M12) back the legal marking Marking 9 (M9), the state equation can be rewritten in Equation (2) as follows:

  • Many experts make their all life to do this research. They use all kinds of algorithms to achieve maximally permissive states. It is a challenging target even they all claimed that their controllers are optimal

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Summary

INTRODUCTION

Nowadays is an era of digitization, mechanization, diversification, and artificial intelligence. It is a pity that they merely demo two small S3PR PNM from [12], according to their conclusion, the proposed method can be applied in pure and bounded Petri net models of FMSs. Based on transition-based techniques, Row and Pan [15] present two novel deadlock prevention algorithms, the All Reachability Graph (ARG) viewpoint and the First Deadlock Marking (FDM) viewpoint, to obtain maximally permissive live states and recover all original deadlock markings for an original PN model.

PRELIMINARY
Procedure of Deadlock Prevention Policy Definition 17
DISCUSSION AND COMPARISON
Findings
CONCLUSION
Full Text
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