Stability analysis of networked control systems subject to packet-dropouts and finite-level quantization (original) (raw)

Stability Results for Networked Control Systems Subject to Packet Dropouts

IFAC Proceedings Volumes, 2005

Stability and performance of networked control systems has been a recent area of interest in the control literature. The inclusion of a shared communication network between plant and controller inevitably leads to occasional random data loss. We provide novel results relating to the probability of such a system being globally asymptotically stable or input to state stable.

Robust H∞ output feedback control of networked control systems with multiple quantizers

Journal of the Franklin Institute, 2012

This paper studies the robust H ∞ control problem of networked linear time-delay systems with discrete distributed delays, involving random packet dropout and quantization. Assume that the measured output of the networked time-delay system can be quantized by the logarithmic quantizer before being transmitted through the communication network. In addition, an appropriate compensation strategy is proposed to reduce the effect of the data packet dropout satisfying a Bernoulli distribution. To deal with the quantization issue, the sector bound method can be used to convert the quantized control problem of the networked system into the robust control problem with uncertainty. Then, a novel observer-based H ∞ output feedback controller is designed to ensure that the networked system is exponentially mean-square stable and an expected H ∞ performance constraint is achieved. Finally, a simulation example is given to prove the effectiveness of the proposed design method. INDEX TERMS Networked control systems, discrete distributed delays, packet dropout, quantization. The associate editor coordinating the review of this manuscript and approving it for publication was Rongni Yang.

Quantized output feedback control for networked control systems

Information Sciences, 2008

The problem of the quantized dynamic output feedback controller design for networked control systems is mainly discussed. By using the quantized information of the system measurement output and the control input, a novel networked control system model is described. This model includes many networkinduced features, such as multi-rate sampled-data, quantized signal, time-varying delay and packet dropout. By constructing suitable Lyapunov-Krasovskii functional, a less conservative stabilization criterion is established in terms of linear matrix inequalities. The quantized control strategy involves the updating values of the quantizer parameters µ i (i = 1, 2)(µ i take on countable sets of values which dependent on the information of the system measurement outputs and the control inputs). Furthermore, a numerical example is given to illustrate the effectiveness of the proposed method.

Stability robustness of networked control systems with respect to packet loss

Automatica, 2007

This paper is concerned with stability analysis of discrete-time networked control systems over a communication channel subject to packet loss whose behavior is modeled by an i.i.d Bernoulli process with a packet dropping probability bounded by a constant. A necessary and sufficient condition for stability is obtained. A packet dropping margin is introduced as a measure of stability robustness of a system against packet dropping, and a formula for it is derived. A design method is proposed for achieving a large margin subject to a constraint that the system has a set of prescribed nominal closed-loop poles. ᭧

Robust H∞output feedback control of networked control systems with dynamic quantizers

2011

Quantization effects are inevitable in networked control systems (NCSs). These quantization effects can be reduced by increasing the number of quantization levels. However, increasing the number of quantization levels may lead to network congestion, (i.e., the network needs to transfer more information than its capacity). In this paper, we investigate the problem of designing a robust H∞output feedback controller for discrete-time networked systems with an adaptive quantization density or limited information. More precisely, the quantization density is designed to be a function of the network load condition which is modeled by a Markov process. A stability criterion is developed by using Lyapunov-Krasovskii functional and sufficient conditions for the existence of a dynamic quantized output feedback controller are given in terms of Bilinear Matrix Inequalities(BMIs). An iterative algorithm is suggested to obtain quasi-convex Linear Matrix Inequalities (LMIs) from BMIs. An example is presented to illustrate the effectiveness of the proposed design.

Design of feedback quantizers for networked control systems

Submitted to Int. J. …, 2008

This paper deals with the design of feedback quantizers to encode plant output measurements in networked control systems with data-rate constrained channels. Starting form a nominal design made under the assumption of transparent communication links, we show how to design a feedback quantizer so as to systematically reduce the impact of quantization on closed loop performance. To obtain our results, we model quantization errors as additive white noise with a signal-to-noise ratio constraint. As a byproduct, we obtain a simple characterization of the minimal quantizer signalto-noise ratio that allows one to design a feedback quantizers that guarantees stability. This bound depends only upon the plant and controller unstable poles. If the plant is strongly stabilizable, then the bound is consistent with the absolute minimal data-rate for stabilization obtained in previous work. * The authors are with the

New results on networked control systems with non-stationary packet dropouts

In this study, an improved observer-based stabilising controller has been designed for networked systems involving both random measurement and actuation delays and subject to non-stationary packet dropouts. The developed control algorithm is suitable for networked systems with any type of delays. By the simultaneous presence of binary random delays and making full use of the delay information in the measurement model and controller design, new and less conservative stabilisation conditions for networked control systems are derived. The criterion is formulated in terms of linear matrix inequalities. Detailed simulation studies on representative systems are provided to show the applicability of the developed design technique.

State Feedback Stabilization of Model-Based Networked Control Systems with Uniform Quantization

2007

This paper addresses the problem of stabilizing an model-based networked control system by means of state feedback via network when the state are firstly sampled by update time and then are quantized by uniform quantization. The quantized state are to perform the feedback by updating the model's state. Sufficient stability conditions for uniform quantization schemes for MB-NCS are derived. Simulation examples are used throughout to illustrate the main results.

Output feedback control of networked control systems with packet dropouts in both channels

Information Sciences, 2013

This paper is concerned with the problem of H 1 output feedback control for networked control systems with packet dropouts in both sensor-to-controller and controller-toactuator channels. Packet dropouts in these two links are modeled as two independent Markov chains, whose transition probability matrices are sparse so that it is easy to obtain. Moreover, late arrivals are considered in the model as well. Sufficient conditions for the solvability of design problems of H 1 output feedback controllers are presented and are dependent on the upper bounds of the number of consecutive packet dropouts. The validity of the proposed approaches are illustrated by a numerical example.