Output feedback control of networked control systems with packet dropouts in both channels (original) (raw)
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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.
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With the integration of communication networks and distributed control in modern manufacturing and process industries, networked control systems (NCSs) are becoming increasingly important due to its simplicity, scalability, flexibility, and cost effectiveness. However, there are still significant technical barriers that limit the applications of NCS technologies. Two challenges are network-induced time delay and data packet dropout. Applying a real-time queuing protocol that we developed recently, we are able to limit the sum of the network-induced communication delay and the control computation delay within a control period. This one-period delay is further guaranteed by well designed compensation for control packet dropout. Then, this paper proposes to compensate for the control packet dropout at the actuator using past control signals. Three model-free strategies for control packet dropout compensation, namely, PD (proportional plus derivative), PD2 (Proportional plus up to the second-order derivative), and PD3 (proportional plus up to the third-order derivative) are developed. They are suitable for a large number of NCSs without the need to tune the compensator parameters. The proposed dropout compensation schemes are demonstrated through numerical examples.
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IEEE Access, 2019
This paper presents the new results on the H ∞ control of a class of completely uncertain nonlinear networked control systems with random communication packet dropouts, which is partially considered in this paper. The uncertainties in the plant are assumed to be real and time-varying, as well as norm, bounded. The random packet losses are modeled as a Bernoulli distributed white sequence with known conditions on their probability distribution. The controller was designed as an observer-based H ∞ dynamic, such that the closed-loop system is exponentially mean square stable and the effect of the disturbance input on the controlled output is less than a minimum level γ for all admissible uncertainties. New sufficient conditions for the existence of such a controller are presented and proved based on the linear matrix inequalities' approach. The theory presented is illustrated by a numerical example to show the effectiveness of the developed techniques. INDEX TERMS Network control systems, network communication, nonlinear systems, uncertain systems, observer-based H ∞ controller.
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Automatica, 2009
In this paper, we address fault detection for networked control systems subject to random packet dropout. The packet dropout is assumed to be existing in the sensor-to-controller link and the controller-toactuator link. Both parity space and observer based residual generation and evaluation approaches are proposed. In parity space based fault detection scheme, a new optimization index is proposed to deal with stochastic system parameters caused by random packet dropout, while in observer based scheme, this is accomplished by introducing a reference model. In order to evaluate performance of the designated threshold, the corresponding false alarm rate is given. The two fault detection schemes can ensure both robustness to packet dropout as well as disturbance and sensitivity to fault. An experimental study is employed to verify that the proposed method performs better than the existing approaches.
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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. ᭧