Mutually nonblocking supervisory control of discrete event systems

✍ Scribed by M. Fabian; R. Kumar

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 154 KB
• Volume: 36
• Category: Article
• ISSN: 0005-1098
• DOI: 10.1016/s0005-1098(00)00102-3

✦ Synopsis

A single maximally permissive and nonblocking supervisor to simultaneously ful"ll several marked speci"cations pertaining to a single plant is investigated. Given a plant G and two marked speci"cation languages K and K , a supervisor S is said to be (K , K )-mutually nonblocking if (for i, j"1,2) ¸(G "" S)5K G -¸(G "" S)5K H . This means that when the closed-loop system marks a trace of K G , then it is always able to continue to a trace of K H , also marked in the closed-loop system. Thus, the controlled system can execute traces within one speci"cation while always being able to continue a trace of the other and hence not blocking the other speci"cation. A complete, globally nonblocking and (K , K )-mutually nonblocking supervisor such that ¸(G "" S)-K 6K exists if and only if there exists a controllable mutually nonblocking sublanguage of the union of the speci"cations. There does exist a supremal such language. Furthermore, in the case that each speci"cation is noncon#icting with respect to the pre"x-closure of the other, this supremal language can be calculated by expressing it as the union of the supremal prexx-bounded sublanguages of the respective speci"cations. Finally, we show that the multiply nonblocking supervision of Thistle, Malhame, Hoang and Lafortune ((1997).