| 英文摘要 | Hybrid systems have attracted considerable attention in recent years. Networked control systems are regarded as a typical class of hybrid systems. The stability, optimal control of networked control systems and the performance evaluation of TCP congestion control are studied in this paper based on the modeling, analysis and control synthesis methodology of hybrid systems in this dissertation. Firstly, a survey on the modeling, analysis, control synthesis, application of hybrid systems is presented, also, the motivation and the outline of this dissertation are given. Secondly, the basic features of networked control systems are analyzed, then, a sampled-data feedback control system, one of models of hybrid systems, is used to model the class of networked control systems. The sufficient conditions of the stability for a sampled-data feedback control system with sampling period h and piecewise constant delay at sampling instants is presented by the stability theory of hybrid dynamical systems with delay, based on this result, a controller synthesis procedure is proposed to stabilize the networked control systems with delay. Thirdly, a hybrid automaton with delay (HAD) is addressed to model the class of networked control systems which exhibit multiple continuous dynamics, based on this model, the sufficient conditions of the stability of an equilibrium of the systems are presented, in which the key element is constructing multiple Lyapunov functionals. For the case where the continuous dynamics in the HAD are denoted by linear time invariant systems with delay, the Linear Matrix Inequality (LMI) technique is employed to analyze the stability instead of finding the common functional. Fourthly, a stochastic hybrid automaton is proposed to model the TCP additive increase and multiplicative decrease (AIMD) behavior of the congestion window size of TCP source, which is one of TCP congestion control mechanisms, on the basis of this model, the statistical performance of the congestion window size of TCP source and the throughput in the TCP connection are evaluated. Moreover, for the case where the timeout is a dominant congestion indication of the wide area network (WAN), the timeout mechanism about the retransmission timer is studied, and a more general evaluation results are obtained. Fifthly, the optimal control problem of the constrained and networked control systems in finite time horizon, with 2-norm performance index, is investigated based on the discrete time piecewise affine system (PWA) model, and the optimal solution to this problem is got by combining the dynamical programming and multiparametric quadratic programming techniques. In addition, the optimal controller can be used to stabilize the networked control system. Finally, the conclusions got in this dissertation are summarized, and the further work is also addressed. |
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