Sustainability of Automated Manufacturing Systems with Resources by Means of Their Deadlock Prevention

This paper is devoted to Petri net (PN)-based models of automated manufacturing systems (AMSs) with resources in order to prevent deadlocks in them. Their sustainability can be seen as the result of their deadlock freeness, leading to correct and fluent production, because AMSs with deadlocks work neither correctly nor fluently, need reconstruction and cause downtime in production. The paradigm of such PN models, S3PRs (systems of simple sequential processes with resources), is well known from the deadlock prevention point of view. Here, an extended S3PR (ES3PR) will be explored, with respect to its modelling and deadlock prevention. While in the case of S3PRs, ordinary Petri nets (OPNs) are used for these aims, here, for ES3PRs, generalized Petri nets (GPNs) are used. The reason for such a procedure is the possible presence of multiplex-directed arcs in the structure of PN models of AMSs. The significant alternation is that while, in the former case, the elementary siphons and dependent ones are sufficient for supervisor synthesis, here, in the later case, the GPNs and their siphons have to satisfy the max cs property.