Modeling, Analysis And Control Of Networked Control Systems

The modeling, analysis and control of networked control systems are studied in this dissertation when the controlled process is linear time-invariant system.Firstly, the modeling of networked control systems is presented. The mathematic models of networked control systems with single packet transmission, multiple packet transmission or data packet dropout are developed when the network-induced delay is short time delay. The open-loop mathematic models of networked control systems with long time delay are developed when the system is driven by anyone of the four different modes. The uniformed modeling method for networked control systems with long time delay is proposed. The mathematic model of networked control systems with multiple-input and multiple-output is developed.Secondly, some new concepts including mean value controllability, mean square controllability, mean value observability, mean square observability, mean value stabilization, mean square stabilizability, mean value detectability and mean square detectability of networked control systems are defined in this dissertation. Some sufficient or necessary conditions for networked control systems with corresponding properties are presented.Thirdly, the deterministic control of networked control systems is studied. The realizing methods and conditions of transforming the random time delay to a deterministic time delay are proposed. The step-by-step transform state feedback controller and the controller basing on state prediction are designed. The output feedback controller and multiple-step predicting controller for compensating time delay are designed. The simulation results show the proposed deterministic controllers are right and effective.Fourthly, the stochastic control of networked control systems is studied. The stochastic state feedback controller and the stochastic output feedback controller for networked control systems are designed. Without considering the noise of the system, this stochastic state feedback controller can render networked control systems Exponentially Mean Square Stable. The stochastic state feedback controller and the stochastic output feedback controller for networked control systems with long time delay are designed. The separation principle is proved to still hold in networked control systems with long time delay. Without considering the noise of the system, this stochastic state feedback controller can render corresponding networked control systems Exponentially Mean Square Stable. The step-by-step transform controller for networked control systems with short time delay is designed. This controller can render corresponding networked control systemsExponentially Mean Square Stable. Equivalent discrete optimal performance index problem for networked control systems is studied. The simulation results show the proposed stochastic controllers are right and effective.Fifthly, the stochastic control of Markov networked control systems with long time delay is studied. The state feedback controller and the output feedback controller of Markov networked control systems with long time delay are designed. The separation principle is proved to still hold in such networked control systems.Finally, the stability of networked control systems is analyzed. The second moment stability and stochastically stability of networked control systems are analyzed. The second buffer method is put forward to deal with the wrong order of data packets. The Markov characteristic of network-induced delay in networked control systems is analyzed. The evaluation method of element in state transition matrix is given when the wrong order of data packet is considered. Considering the wrong order of data packets, the mathematic model of networked control systems with long time delay is developed. The sufficient and necessary conditions for stochastic stability of such networked control systems with long time delay are given.