Computationally Improved Optimal Supervisory Control Policy for FMSs Using Petri Nets

Abstract

One novel control policy named selective siphon control policy [1] is proposed to solve deadlock problems in flexible manufacturing systems (FMSs). The novel policy not only solves the deadlock problem successfully but obtains maximally permissive controllers. In existing literature, the policy is the first one to achieve the goal of obtaining maximally permissive controllers for all Systems of Simple Sequential Processes with Resources (S³PR) models. However, the proposed policy cannot check the exact number of maximally permissive states of a deadlock net in advance. After all iterating steps, the final maximally permissive can then be known. Additionally, all legal markings still to be checked again and again until all critical markings vanished. In this work, one computationally improved supervisory control methodology is proposed to solve the two problems. Experimental results show that the proposed methodology is practical and better than existing literatures.