PREPRINTS 12 th International Workshop on Real Time Networks RTN

The Networked Control Systems are a very important research area because of their multidisciplinary aspect ( Automatic Control, Computer Science, Communication Network). Here we only consider the aspect (Automatic Control, Communication Network) by focusing on Wireless LANs ( WLANs) based on a Collision -Free CSMA type MAC protocol ( the collision -free property is got by using priorities which allow to transform a situation, which would be a ”collision situation ” with a strict CSMA type protocol, into a ”winner-looser(s) situation”; such a protocol is called the CANlike protocol). The aim of the paper is, by considering several process control applications distributed on a WLAN, to present a co-design ,of the frame scheduling of the frames of the process control applications AND of the controllers of these applications, on the basis of a bidirectional relation between the Quality of Control (QoC) provided by the controllers and the Quality of Service(QoS) provided by the scheduling of the frames on the WLAN ( relation QoC ← QoS) i-e we have both the relation QoC → QoS ( QoS is QoC driven i-e we have a ”Application performances aware dynamic QoS adaptation”) and the relation QoS → QoC (QoC is QoS driven i-e we have a ”Network performances aware dynamic QoC adaptation” ). The relation QoC → QoS is implemented by considering hybrid priorities for the frame scheduling( it is the dynamic part of these priorities which provides this relation QoC → QoS) .The relation QoS→ QoC is implemented on the basis of the delay compensation method called dominant pole method. Finally we show the interest of the proposed co-design approach in order to have an efficient control system.