No abstract

A new proportional-derivative-type state feedback controller is proposed for congestion control of transmission control protocol (TCP) networks. An analytical TCP model is adopted. In the proposed control scheme, it is possible to efficiently control the TCP traffic using only the queue length at the router without the need to know the TCP window size which is not available locally. The results are presented in terms of delay-dependent linear matrix inequality. The proposed method is verified by simulation examples using NS software, and the effectiveness and superiority of our method over other control schemes, such as the proportional-integral, random early detection and generalised minimum variancemethods, are also shown.

This paper presents a new model for networked control systems (NCSs) under transmission control protocol (TCP) as a multiple‐delay system by considering both sensor to controller and controller to actuator delays. An analytical TCP model has been considered for the network part, and an active queue management (AQM) controller is designed to regulate the desired queue length, which ensures holding the network induced delay and its variation within their lower bounds. The model is assumed to possess structured uncertainties due to the stochastic nature of the network. Robust stability and stabilization conditions are derived in terms of linear matrix inequalities (LMIs) by applying the Lyapunov‐Krasovskii stability criterion. Illustrative examples are presented and it has been shown that the proposed method will obtain less conservative results compared to the existing approaches in the literature.

Based on the fact that the queuing delay involved in the congestion control algorithm is state-dependent, the model of communication over TCP network protocol is transformed to a state-dependent delay differential equation. Hence, our paper firstly presented a sufficient condition for the stability of this class of systems. The results are presented in terms of linear matrix inequality (LMI). After, the general results obtained are applied to design an Active Queue Management (AQM) scheme for congestion control in internet. The proposed method is verified by simulation examples using NS software and the effectiveness and superiority of our method with respect to other control schemes such as PI and RED is shown.

This paper considers the robust stability of uncertain teleoperation systems. Sufficient stability conditions are derived in terms of LMI by representing the teleoperation scheme in retarded form of time-delay systems. By choosing Lyapunov-Krasovski functional, a delay-independent robust stability criterion is presented. We show that the teleoperation system is stable and has good performance under specific LMI condition. With the given controller parameters, stability of system is guaranteed in the presence of any value of delay and admissible uncertainty. To evaluate the theoretical analysis, Numerical simulations are performed.