State Feedback Control Of Networked Control Systems

Networked control system (NCS) is a feedback control system whose sensors, controllers and actuators are all connected via networks. It is the collaboration of three engineering fields, computer engineering, communication engineering and control engineering, and has become the new direction of modern industry. However, a series of network problems can be brought simultaneously, such as network-induce delay, data packet loss, packet disorder and so on. These are main factors to degrade the performance of control systems. The main contributions of this dissertation for issues of network-induced delay and data packet loss are listed as follows:(1) Purpose and significance of NCS and current research methods on network-induced delay and data packet loss in NCS are introduced. And the research and development of state feedback control in NCS has been learned base on the relevant literature.(2) The problem of state feedback control with network-induce delay which exists both between sensor and controller and between controller and actuator in NCS is investigated. Based on Lyapunov stability theory and time-delay system stability theory, a sufficient condition for the existence of state feedback controller is given in the form of linear matrix inequalities and a design method is also presented, ensuring that NCS is asymptotically stable. A numerical example illustrates the controller effectively improves the performance of the system stability.(3) For the network channel with data packet dropout, NCS is modeled as an asynchronous dynamical system with rate constrains on events. By using the asynchronous dynamical systems approach and solving the linear matrix inequality, the precise relation between the packet dropout rate and the stability of the closed-loop NCS is presented. Analyzing the situation of data transmission rate, a sufficient condition is given in order to make system exponentially stability and a design method for the existence of state feedback controller is also presented ensuring that NCS is mean square stability. Numerical examples verify the effectiveness of this method.(4) NCS with network-induce delay and data packet dropout exists in the forward and backward channels are discussed. By modeling NCS with data packet loss into an asynchronous system, it deals with the impact of the long time delay as a known bound of uncertainty. For the given data transmission rate, a sufficient condition for the existence of controller is given and how to design the state feedback controller. Finally, the simulation example demonstrates the state feedback controller which makes the closed-loop system stable with a prescribed H-infinity performance.