Stability Analysis And Design Of Networked Control System With Data Packet Dropout

The NCS is a feedback control system wherein the sensors, actuators andcontrollers as the network nodes connected through the computer network orfieldbus to accomplish the control tasks. With the rapid development,popularization and increasingly perfect of the computer networks technology,the control system based on the Networked Control System (NCS) has becomeone of the hot research task in current international control field. The researchon NCS has important theoretical meanings and also NCS has extensiveapplication prospects. Different from the traditional control systems, thedistinct characteristic of NCS is that the network communication is one of theimportant parts of the control system. Because of the network-induced timedelay which is often uncertain and time-varying, and the transmitted data erroror data dropout, the NCS is no longer a constant, maturity and certainty. Alsobecause of the event-driven and time-driven coexisted in NCS, so it is requirednew views and more sustaining theories to the study on NCS, which bringsforward newly challenge and development opportunity to the investigation ofthe control theory.This thesis systematically analyzes the characteristics of networkedcontrol system, network-induced time delays and network data packet dropoutetc, and the effects made onto the control performances, then propose newlydesigned methods which solve the stability and robustness problems of thecontrol system brought by the network-induced time delays and the data packetdropout.Firstly, in terms of the network-induced time delays, we consider the NCSdesign problem with the delays less than one sample period (which can becalled short delays). Based on the network-induced delays' Markovcharacteristics, we propose the NCS Markov jump models, present thesufficient conditions for the stability of the NCS, and give the state feedbackcontroller design methods. Furthermore, considering the linear continuoussystem with the short delays and the uncertain parameters, estimating the maxbound of the transmission delays by Lyapunov theory, and the systemsasympotic stability condition is given. Also the simulation examples are givento illustrate the effectiveness of the proposed methods.Secondly, considering the NCS stability problem when data-packetsdropout happening during the whole transmission route. Based on thedata-packets dropout' Markov characteristics, we propose the NCS Markovjump models, then get the system stability condition by Lyapunov stabilitytheory and LMI. Also the simulation examples are given to illustrate theeffectiveness of the proposed methods.Finally, network data packet dropout is another issue in NCS, which candegrade the system's performance and even can make the system instable. Soas for the NCS with data packet dropout and network-induced time delays, thispaper proposes a new modeling method. According to the controller updateinformation when the data packet lost, two different schemes are given: one isadopting the latest arrival data information at the previous sample time toupdate the controller, another is designing a data packet dropout compensator,using the compensator's data information to update the controller. In theproblem analysis, we set up the model of the Asynchronours dynamical systemwith data-packet dropouts. Based on the Lyapunov stability theory, we presentthe sufficient conditions for the stability of the two different closed NCSmodels, respectively. Also simulation examples are given to illustrate thevalidity of the results.