Design of State-Based Schedulers for a Network of Control Loops
2013 (English)In: IEEE Transactions on Automatic Control, ISSN 0018-9286, E-ISSN 1558-2523, Vol. 58, no 8, 1962-1975 p.Article in journal (Refereed) Published
For a closed-loop system with a contention-based multiple access network on its sensor link, the medium access controller (MAC) may discard some packets when the traffic on the link is high. We use a local state-based scheduler to select a few critical data packets to send to the MAC. In this paper, we analyze the impact of such a scheduler on the closed-loop system in the presence of traffic, and show that there is a dual effect with state-based scheduling. In general, this makes the optimal scheduler and controller hard to find. However, by removing past controls from the scheduling criterion, we find that certainty equivalence holds. This condition is related to the classical result of Bar-Shalom and Tse, and it leads to the design of an innovations-based scheduler with a certainty equivalent controller. However, this controller is not an equivalent design for the optimal controller, in the sense of Witsenhausen. The computation of the estimate can be simplified by introducing a symmetry constraint on the scheduler. Based on these findings, we propose a dual predictor architecture for the closed-loop system, which ensures separation between scheduler, observer and controller. We present an example of this architecture, which illustrates a network-aware event-triggering mechanism.
Place, publisher, year, edition, pages
2013. Vol. 58, no 8, 1962-1975 p.
Event-based systems, networked control systems, state-based schedulers
Electrical Engineering, Electronic Engineering, Information Engineering Control Engineering
IdentifiersURN: urn:nbn:se:kth:diva-127482DOI: 10.1109/TAC.2013.2251791ISI: 000322364300006ScopusID: 2-s2.0-84880913768OAI: oai:DiVA.org:kth-127482DiVA: diva2:645652
FunderSwedish Research CouncilVinnovaSwedish Foundation for Strategic Research Knut and Alice Wallenberg FoundationEU, European Research Council
QC 201309052013-09-052013-08-302013-09-05Bibliographically approved