Abstract—Wireless Networked Control Systems (NCS) are increasingly deployed to monitor and control Cyber-Physical Systems (CPS). To achieve and maintain a desirable level of performance, NCS face significant challenges posed by the scarce wireless resource and network dynamics. In this paper, we consider NCS consisting of multiple physical plant and digital controller pairs communicating over a multi-hop wireless network. The control objective is that the plants follow the reference trajectories provided by the controllers. This paper presents a novel optimization formulation for minimizing the tracking error due to (1) discretization and (2) packet delay and loss. The optimization problem maximizes a utility function that characterizes the relationship between the sampling rate and the capability of disturbance rejection of the control system. The constraints come from the wireless network capacity and the delay requirement of the control system. The solution leads to a joint design of sampling rate adaptation and network scheduling, which can be naturally deployed over existing networking systems which have a layered architecture. Based on a passivity-based control framework, we show that the proposed cross-layer design can achieve both stability and performance optimality. Simulation studies conducted in an integrated simulation environment consisting of Matlab/Simulink and ns-2 demonstrate that our algorithm is able to provide agile and stable sampling rate adaptation and achieve optimal NCS performance. Index Terms—wireless networked control system; cross-layer design; sampling rate adaptation; network scheduling I.

Abstract—Digital networked control systems are of growing importance in safety-critical systems and perform indispensable function in most complex systems today. Networked degradations such as transmission delay and packet dropout cause such systems to fail to satisfy performance requirements, and eventually affect the overall reliability. It is necessary to get a model to verify and evaluate the system reliability in early design phase, prior to its implementation. However, existing probabilistic models only provide partial descriptions of such coupled networks and control system. In this paper, a new stochastic model represented by linear discrete-time approach is proposed, considering data packet transmissions in both channels: controller-to-actuator and sensor-to-controller. Different from pervious works, the historical behaviors of networked degradations are modeled by multistate Markov chains with uncertainties, releasing the assumption that

In cyberphysical systems, where compositionality of design is an important requirement, passivity and dissipativity based design methods have shown a lot of promise. Although these concepts are classical, their application to cyberphysical systems poses new and interesting challenges. The aim of this paper is to summarize some of the on-going work in this area by the authors. I.