Networked Control Systems

Abstract

ForewordThis book finds its origin in the WIDE PhD School on Networked Control Systems, which we organized in July 2009 in Siena, Italy. Having gathered experts on all the aspects of networked control systems, it was a small step to go from the summer school to the book, certainly given the enthusiasm of the lecturers at the school. We felt that a book collecting overviews on the important developments and open problems in the field of networked control systems could stimulate and support future research in this appealing area. Given the tremendous current interests in distributed control exploiting wired and wireless communication networks, the time seemed to be right for the book that lies now in front of you.The goal of the book is to set out the core techniques and tools that are available for the modeling, analysis and design of networked control systems. Roughly speaking, the book consists of three parts. The first part presents architectures for distributed control systems and models of wired and wireless communication networks. In particular, in the first chapter important technological and architectural aspects on distributed control systems are discussed. The second chapter provides insight in the behavior of communication channels in terms of delays, packet loss and information constraints leading to suitable modeling paradigms for communication networks.The second part focuses on decentralized and distributed control, estimation and optimization. The network aspect is here that not all information is available in one central controller, estimator or optimizer, but local agents have only limited information of the overall control, estimation or optimization problem and still aim at solving the central problem in an appropriate manner. Although the information might be limited for each individual agent, it is assumed that communication is ideal and imperfections such as communication delays, possible loss of information and quantization effects are ignored. Chapter 3 discusses distributed estimation and consensus problems and the fourth chapter surveys distributed optimization techniques. Chapter 5 and 6 provide overviews on decentralized and distributed control. The emphasis in chapter 5 is on decentralized and distributed model predictive control techniques. VI ForewordWhile communication imperfections induced by the presence of a non-ideal and uncertain network channel are ignored in the second part of the book, they form the main topic of the third part. Methods for stability analysis and controller synthesis of control loops closed over communication channels are treated in chapter 7. Using appropriate models of networked control systems it is investigated how networkinduced phenomena such as varying delays, varying sampling intervals, data loss and communication constraints influence the stability and performance of control loops. Chapter 8 studies the effects of the limited capacity of channels, e.g. limited bandwidth, on feedback control. Fundamental limitations in control using quantized infor...

A review of component-in-the-loop: Cyber-physical experiments for rapid system development and integration

“…[34][35][36][37] One of the key challenges is of course the delay (and packet loss) caused by the network, which is a major topic of research in the field of networked control systems. 38…”

Robustness of Nonlinear Control Systems to Network-Induced Imperfections

“…which can be readily employed provided ( ) is known. In order to obtain known delays, one can intentionally delay the communicated signals via time-stamping of data and introduction of buffers at receiver ends [2][3][4]6]. After applying the methodology from Section 4, we obtain Figs.4 and 5 for scenarios with an unspecified des and with des = 15 specified a priori.…”

“…With the advent of more advanced hardware and software components, modern control systems are frequently being implemented over a shared (wired or wireless) resource-constrained communication network [1][2][3][4][5][6][7][8][9]. In particular, spatially distributed sensors, controllers and actuators in such control systems, termed Networked Control Systems (NCSs), do not exchange information through dedicated point-to-point connections.…”

“…The controller and plant are interconnected according to Fig. 1, that is, the quantity � is the distorted and delayed version of received by the controller (1) while the quantity � is the distorted and delayed control input fed to the plant (2). The translation operators and , defined in Section 2.2, are with the corresponding controller and plant delays ≥ 0 and ≥ 0, respectively.…”

“…The translation operators and , defined in Section 2.2, are with the corresponding controller and plant delays ≥ 0 and ≥ 0, respectively. The main goal of this work is to find/estimate the L p -gain, where ∈ [1, ∞], from ( , ) to � , � for the NCS (1)- (2) in the presence of some sampling intervals, model-based estimators, noise levels, scheduling protocols and NCS link delays.…”