Analysis And Design Of Networked Control Systems With Time-delay And Data Packet Dropout

The optimal control and stability analysis for networked control systems with time-delay and data packet dropout are studied in this dissertation when the network-induced delay and packet dropout as two basic questions are study objects.Firstly, the stability analysis and optimal control for networked control systems with data packet dropout are presented. To the discrete-time plants existed packet loss in both forward path and feedback path, this paper differently takes the process of data packet loss as independent Bernoulli processes. By the restrict conditions of the level parameters of the quantizers, we can guarantee the mean-square stability in state estimation and acquire an upper bound of the biggest packet loss rate of forward path based on the above constrained conditions. Meanwhile, based on the performance criterion of Linear Quadratic Gaussion (LQG), we present the optimal control law of the system under data packet loss, and optimal design method based on the technique of linear matrix inequality (LMI) and bisection method. Then, an optimum algorithm on the biggest packet loss rate of feedback path is also given. Finally, we give some simulation examples to verify the theoretical results.Secondly, design of compensation algorithm and optimal control law of networked control system with time delays are studied. In view of the system existence random time delays, we design state observers separately under the full condition feedback system and the output feedback system to realize the time delays compensation, thus we can obtain the more accurate forecast estimate. Meanwhile, we present the optimal control law of the networked control system based on LQG performance, to weaken the influence of time delays and system noise on system stability, so we can ensure the stability of the system. Finally, passed the example simulation, we confirmed the validity of the time delay compensation strategy and the optimum control design.Thirdly, exponential stability of networked control system with time-delay and data packet dropout is studied. NCS with both network-induced delay and data Packet dropout is modeled as an Asynchronous Dynamical System (ADS) constrained by configuration event rates. Supposing the NCS without data Packet dropout is stable, the sufficient condition for the exponential stability of the NCS with fixed data packet rate is derived by using Lyapunov theory and linear matrix inequality formulation. The relationship between open-loop system status,closed-loop configuration and allowable packet dropout rates is presented to guarantee the exponential stability of NCS and the state feedback control law is obtained. The simulation data demonstrated the feasibility of the method.Finally, the model of compensation and estimation for the networked control system with time-delay and data packet dropout is designed. When the data packet is lost, controlling object is realized through designing estimation compensator for data packet dropout of the system and using its information to update the output of the controller. Simulation results prove that the networked control system with compensator and estimator can effectively reduce time-delay and the impact of date packet dropout on the system, and it also can effectively improve the stability performance of control systems. Thus, it is verified that the design is feasible and effective.