Research On Analysis And Design For Networked Control Systems With Long Time-delay

In this dissertation, the main problems of network-induced delay, data packet dropout and additive disturbance in networked control systems with long time-delay are considered. Basing on the quality of service of control networks, surrounding the quality of performance of NCS, the problems of modeling, stability analysis, optimal control, guaranteed cost control, H-infinity control for NCS are studied. The main contributions of this dissertation are as follows:1. Based on the fuzzy fusion technology, a modeling approach for networked control systems with network-induced long time-delay is proposed. The system with long control time-delay is transformed into the one without time-delay. By using the probability of time-delay appearance as membership degree, the global T-S fuzzy model is set up. According to the model, a states observer is designed and the disturbance arising from calculation is cancelled. Then the stability of the closed-loop system is analyzed and the conditions of asymptotic stability are proposed.2. Based on the fuzzy fusion technology, a modeling approach for networked control systems with network-induced time-delay which is probably longer than a sampling period is studied. The system with control time-delay is transformed into the one without time-delay. The Kalman filter is employed for the optimal state estimate of white-noise processes and the physically realizable problem of optimal disturbance rejection control law is solved. Then the existence and uniqueness conditions of feedforward and feedback optimal control law are proposed, and the algorithm of solving the optimal control problem is presented.3. By means of Try-Once-Discarded (TOD) technology, an approach of modeling for networked control systems with both data packet dropout and transfer delay is presented. The effect of random time-delay to the systems is regarded as the unknown bounded uncertain item. Based on the network-induced delay which is likely longer than a sampling period, the networked control system is modeled as an asynchronous dynamical system with rate constraints on events. Via the conclusion of the linear matrix inequality (LMI), the sufficient condition to the exponential stability of the networked control system is derived and the rage that must be satisfied by the data transmission rate is proposed.4. A disturbance rejection problem for a class of uncertain nonlinear networked control systems affected by additive persistent disturbances is considered. We present a state variable substitution which transfers the control time-delay to the outside of control closed-loop such that the impact of time-delay part to control system stability is eliminated. An approach to design zero steady-state error disturbance rejection compensator is proposed via the internal model principle. The Lyapunov stability theory and linear matrix inequality technology are employed to testify the existence conditions of guaranteed cost control law and to design a zero steady-state error guaranteed cost control strategy.5. A non-fragile control problem for a class of uncertain nonlinear networked control systems with long time-delay and controller gain perturbations is considered. Firstly, the NCS model with random long time-delay is transformed into a discrete-time system model with uncertain parameters. Then, the Lyapunov stability theory and the linear matrix inequality approach are applied to design a non-fragile controller, which results in that the closed-loop system is asymptotically stable and the system's cost function value is less than a determinate upper bound. At the same time, the existence condition and the design approach of non-fragile controller are presented.6. An H-infinity guaranteed cost control problem for a class of uncertain nonlinear networked control systems with long time-delay is considered. Firstly, the networked control system model with random long time-delay is transformed into a discrete-time system model with uncertain parameters. Then, the Lyapunov stability theory and the linear matrix inequality approach are applied to present the existence condition and the design approach of H-infinity guaranteed cost controller. Furthermore, the optimal robust H-infinity guaranteed cost controller can be obtained through solving the corresponding convex optimization problem.Finally, the conclusions are given, and a proposition is indicated on the research work in the future.