An approach to specification simplification in automated manufacturing systems using invariance and inequality analysis

Supervisory control techniques (SCTs), as one of the fundamental researches in the domain of automated manufacturing systems, implement specifications upon a plant model, leading the system to tendentiously desired behaviors. Generalized Mutual Exclusion Constraints (GMECs) are a typical kind of SCTs which correspond to a linear supervisory specification in the context of Petri nets (PNs). Given a set of admissible GMECs, supervisor simplification is needed to reduce implementation cost and mitigate fabrication complexity. In this paper, two methods are proposed and improved in the paradigm of arbitrary GMECs simplification. For the method based on P-invariant control, it develops in the semantics of PN structure analysis, exhibiting drawbacks like low computational efficiency, high failure probability, and definite failure to control weakly L1-dependent inequalities. On the contrary, for the method based on inequality analysis, it germinates on the ground of algebra theory, tackling both L1- and L2-dependent inequalities. Experimental results show the effectiveness and efficiency of supervisor simplification based on inequality analysis.