[Legacy Report] SMCS Seminar: Deadlock-free and Ratio-enforced Supervision of Automated Manufacturing Systems Using Petri Nets

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In automated manufacturing systems (AMSs), Petri nets are widely adopted to solve the supervisory control problems. Among them deadlock-freeness and fairness constitute two important parts. The former ensures no occurrence of deadlock situations so as to inhibit the emergence of the partial or complete block for the processing of jobs. The latter ensures a reasonable regulation scheme for orderly resolution such that a desired ratio can be achieved among different processes. This work proposes an efficient method to design the supervisors, which are based on the invariance property of Petri net models of AMSs. A novel approach is proposed to iteratively produce empty siphons as the solutions of a set of linear inequalities. We show that the implementation of these two supervisors can be separately performed. The applicability of these results is illustrated through examples. Comparison with the previous work is presented to demonstrate the advantages of the proposed approach.

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