Qing-Long Han

State feedback controller design of networked control systems

This work is concerned with the controller design of networked control systems (NCSs). A new model of NCSs is provided under consideration of both the network-induced delay and the data packet dropout in the transmission. In terms of the given model, a controller design method is proposed based on a delay dependent approach. The feedback gain of a memoryless controller and the maximum allowable value of the network-induced delay can be derived by solving a set of linear matrix inequalities. Two examples are given to show the effectiveness of our method.

A Delay System Method for Designing Event-Triggered Controllers of Networked Control Systems

This note is concerned with event-triggered H∞ controller design for networked control systems. A novel event-triggering scheme is proposed, which has some advantages over some existing schemes. A delay system model for the analysis is firstly constructed by investigating the effect of the network transmission delay. Then, based on this model, criteria for stability with an H∞ norm bound and criteria for co-designing both the feedback gain and the trigger parameters are derived. These criteria are formulated in terms of linear matrix inequalities. Simulation results have shown that the proposed event-triggering scheme is superior to some existing event-triggering schemes in the literature.

Technical communique: Absolute stability of time-delay systems with sector-bounded nonlinearity

This paper deals with the problem of absolute stability of time-delay systems with sector-bounded nonlinearity. Some new delay-dependent stability criteria are obtained and formulated in the form of linear matrix inequalities (LMIs). Neither model transformation nor bounding technique for cross terms is involved through derivation of the stability criteria. Numerical examples show that the results obtained in this paper improve the estimate of the stability limit over some existing result.

Delay-dependent exponential stability of stochastic systems with time-varying delay, nonlinearity, and Markovian switching

The problem of delay-dependent stability in the mean square sense for stochastic systems with time-varying delays, Markovian switching and nonlinearities is investigated. Both the slowly time-varying delays and fast time-varying delays are considered. Based on a linear matrix inequality approach, delay-dependent stability criteria are derived by introducing some relaxation matrices which can be chosen properly to lead to a less conservative result. Numerical examples are given to illustrate the effectiveness of the method and significant improvement of the estimate of stability limit over some existing results in the literature.

On H∞ control for linear systems with interval time-varying delay

A centrifuge drum has a chamber that can accommodate fluid formed by a concentric component inserted into the drum. The concentric component has a sealing ring accommodated in an annular groove at its outer diameter. The base of the annular groove can be supplied with control medium through a channel and emptied again through an outlet device. When the channel is full, the sealing ring is forced against a cylindrical surface and seals off an annular gap. When the channel is empty, the pressure of the fluid in the chamber forces the sealing ring in, releasing the annular gap for the chamber to empty through. In addition to acting as a seal, the sealing ring also acts as a valve, and allows a very simple design for all types of centrifuge-drum chambers that must be filled and emptied again during operation.

Technical Communique: Robust stability of uncertain delay-differential systems of neutral type

This paper focuses on the stability problem for neutral delay-differential systems with norm-bounded, and possibly time-varying, uncertainty. The time-delay is assumed constant and known. A stability criterion that is formulated in a linear matrix inequality (LMI) form is derived. Numerical examples show that the results obtained by this new criterion significantly improve the estimate of stability limit over some existing results in the literature.

A distributed event-triggered transmission strategy for sampled-data consensus of multi-agent systems☆

Abstract This paper is concerned with event-triggered sampled-data consensus for distributed multi-agent systems with directed graph. A novel distributed event-triggered sampled-data transmission strategy is proposed, which allows the event-triggering condition to be intermittently examined at constant sampling instants. Based on this novel strategy, a sampled-data consensus control protocol is presented, with which the consensus of distributed multi-agent systems can be transformed into the stability of a system with a time-varying delay. Then, a sufficient condition on the consensus of the multi-agent system is derived. Correspondingly, a co-design algorithm for obtaining both the parameters of the distributed event-triggered transmission strategy and the consensus controller gain is proposed. Two numerical examples are given to show the effectiveness of the proposed method.

A New

This note is concerned with robust Hinfin control of linear networked control systems with time-varying network-induced delay and data packet dropout. A new Lyapunov-Krasovskii functional, which makes use of the information of both the lower and upper bounds of the time-varying network-induced delay, is proposed to drive a new delay-dependent Hinfin stabilization criterion. The criterion is formulated in the form of a non-convex matrix inequality, of which a feasible solution can be obtained by solving a minimization problem in terms of linear matrix inequalities. In order to obtain much less conservative results, a tighter bounding for some term is estimated. Moreover, no slack variable is introduced. Finally, two numerical examples are given to show the effectiveness of the proposed design method.

H_{{\bm \infty}}

This paper is concerned with the delay-dependent robust stability problem for uncertain linear systems with interval time-varying delay. The time-varying delay is assumed to belong to an interval and no restriction on the derivative of the time-varying delay is needed, which allows the delay to be a fast time-varying function. The uncertainty under consideration is norm-bounded, and possibly time-varying, uncertainty. Based on the Lyapunov-Krasovskii functional approach, a stability criterion is derived by introducing some relaxation matrices that can be used to reduce the conservatism of the criteria. Numerical examples are given to demonstrate effectiveness of the proposed method.

Stabilization Criterion for Networked Control Systems

The robust stability of uncertain linear neutral systems with discrete and distributed delays is investigated. The uncertainties under consideration are norm bounded, and possibly time varying. The proposed stability criteria are formulated in the form of a linear matrix inequality and it is easy to check the robust stability of the considered systems. Numerical examples are given to indicate significant improvements over some existing results.