Several Control Problems Of Networked Systems Based On Predictive Control

Networked control systems (NCSs), which integrate control, communication and micro-electronics technology, have received much attention in the international control community. With the fast development of networked control technology, more and more agents work autonomously using information of other agents over the communication network, which are termed networked multi-agent systems (NMAS) such as the Internet of Things (IoT). Networked Systems in the existing research consist of NCS and NMAS, and NCS is a special structure of NMAS. Compared with conventional control systems, the NMAS offer many advantages, such as flexibility, parallelism and reliability. The dis-tributed nature of NMAS is more applicable to an uncertain and complex environment. Thus, the distributed coordination of NMAS has broad applications in many aeras includ-ing formation control of unmanned air vehicles (UAVs), intelligent transportation and distributed estimation of sensor networks. Owing to the introduction of communication networks to control systems, network-induced delays and dropout packet phenomenon are almost unavoidable, which often degrade control performance and affect system stability. In fact, the issue of the controller design and stability analysis for networked systems with communication delays and data dropout is a really hard task.This dissertation considers several control problems for networked systems with communication delays and data dropout. Based on time delay and data dropout com-pensation scheme, the simple approaches to design predictive controllers are proposed for NCS and NMAS. Design and stability criteria of networked systems, which are not related to network characteristic, are presented mainly using stability and consensus ana-lytical theory. The main topics covered in this dissertation are detailed as follows:In Chapter1, a brief introduction to the research background, which includes current progress in the study of NCS and NMAS, is presented. On this basis, the main contents and organization of the dissertation are given.In Chapter2, regulation and tracking control problems of linear networked control systems are studied, where network delays in both forward and feedback channels are taken into account. During the networked predictive regulator design process, two differ-ent network delay compensation schemes are provided in two cases:the controlled plant whose state vectors can be measured and the one whose state vectors cannot be mea-sured. Further discussions on stability and uncertainty analysis for networked predictive regulating systems are given. In addition to networked regulation, the networked track-ing problem is also addressed. The networked predictive tracking controller is designed and the stability and performance analysis are detailed. The analytical results show the networked predictive controllers are independent of the network delays.Chapter3considers predictive controller design for a class of nonlinear networked systems with network delay and data dropout. In order to remove the effects of the com-munication delay and data dropout, the nonlinear networked predictive control scheme is proposed. The theoretical results demonstrate the stability of the close-loop nonlinear predictive control system is not related to network delays and data dropout.Chapter4addresses the leaderless and leader-following consensus controller design for NMAS with network delays and/or data dropout based on the networked predictive control scheme. Leader-following consensus predictive controllers can be used to solve the synchronization problem of NMAS. Furthermore, another key part of this chapter is to analyse the stability and consensusability of closed-loop NMAS on the basis of the designed predictive controller. Finally, simulation results illustrate the feasibility and efficacy of the proposed method.Based on the results obtained in Chapter4, the group consensus, which is a more general consensus problem, is further studied together with network delays in Chapter5. A state-based predictive approach for group consensus controllers is proposed for NMAS with time-varying delays and a number of criteria for group consensusability of NMAS with network delays are presented. Finally, the effectiveness of the proposed approach is demonstrated through numerical simulations.