NetworkedControlSystems.PDF

Implementation Considerations For Wireless Networked Control Systems Payam Naghshtabrizi and Jo˜ao P. Hespanha Abstract We show that delay impulsive systems are a natural framework to model wired and wireless NCSs with variable sampling intervals and delays as well as packet dropouts. Then, we employ discontinuous Lyapunov functionals to charac- terize admissible sampling intervals and delays such that exponential stability of NCS is guaranteed. These results allow us to determine requirements needed to es- tablish exponential stability, which is the most basic Quality of Performance (QoP) required by the application layer. Then we focus on the question of whether or not the Quality of Service (QoS) provided by the wireless network suffices to fulfil the required QoP. To answer this question we employ results from real-time scheduling and provide a set of conditions under which the desired QoP can be achieved. 1 Introduction Network Control Systems (NCSs) are spatially distributed systems in which the com- munication between sensors, actuators, and controllers occurs through a shared band-limited digital communication network, as shown in Fig. 1. There are two types of NCSs in terms of medium used at the physical layer: wired and wireless. Wired NCSs have been used widely in automotive and aerospace industry [14] to reduce weight and cost, increase reliability and connectivity. Particularly drive-by- wire and fly-by-wire systems have shown a high penetration rate in these industries. In wireless NCSs, the communication relies on the wireless technology and it has been finding applications in a broad range of areas that in which it is difficult or expensive to install wire, such as mobile sensor networks [17], HVAC systems [1], automated highway and unmanned aerial vehicles [18]. In both the wired and wireless domains, use of a shared network—in contrast to using several dedicated independent connections—introduces new c